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Sample records for diamond tool wear

  1. Wear mechanism of diamond coated cutting tools

    SciTech Connect

    Leyendecker, T.; Lemmer, O.; Esser, S.

    1995-12-31

    Since Diamond Coatings were introduced into the market in 1989, five years experience in industrial applications of diamond coated cutting tools enables to present an overview of tool life and wear behavior of diamond coated cutting tools due to different cutting conditions and workpiece-materials. Machining reinforced plastics, presintered ceramic compacts, aluminum alloys, metal-matrix composites and graphite, different wear behavior occurs at the cutting edges of diamond coated tools. Having a good adhesion fatigue and chemical wear of Diamond coatings determines life time of the tools. By a profound pretreatment procedure CVD Diamond coated tools can compete with conventional PCD-tools.

  2. Wear Test Of A Preselected Diamond Tool

    NASA Astrophysics Data System (ADS)

    Hurt, H. H.; Showman, G. A.

    1987-02-01

    An investigation was conducted to develop a set of criteria that would allow the typical user to preselect a diamond-turning tool for the most critical optical finishing operations. A wide variety of tools used in this study had their edge quality evaluated by Nomarski and scanning electron microscopy methods, and the diamond crystal orientation and quality were determined by Laue x-ray methods. One of the tools was subjected to a long-term machining test to evaluate the tool wear process and to correlate the wear observed with changes in the scattering properties of the surface.

  3. Diamond tool wear of electrodeposited nickel-phosphorus alloy

    SciTech Connect

    Dini, J.W.; Donaldson, R.R.; Syn, C.K. ); Sugg, D.J. )

    1990-02-01

    Nickel-Phosphorus alloys are attractive materials for diamond turning applications such as fabrication of large optics and other high precision parts. Although the mechanism is not understood, diamond tool wear is minimized when the phosphorus content of the deposit is greater than 11% (wgt). In recent years, increased attention has been directed at electrodeposition as an alternate to electroless deposition for producing Ni-P alloys. One principal advantage of the electrodeposition process is that alloys with 14--15% P can be obtained; another is that an order of magnitude greater deposition thickness can be provided if necessary. This paper compares diamond turning results for electrodeposited and electroless Ni-P alloys and shows that the electrodeposited coatings provide promising results. 28 refs., 7 figs., 1 tab.

  4. Diamond Smoothing Tools

    NASA Technical Reports Server (NTRS)

    Voronov, Oleg

    2007-01-01

    Diamond smoothing tools have been proposed for use in conjunction with diamond cutting tools that are used in many finish-machining operations. Diamond machining (including finishing) is often used, for example, in fabrication of precise metal mirrors. A diamond smoothing tool according to the proposal would have a smooth spherical surface. For a given finish machining operation, the smoothing tool would be mounted next to the cutting tool. The smoothing tool would slide on the machined surface left behind by the cutting tool, plastically deforming the surface material and thereby reducing the roughness of the surface, closing microcracks and otherwise generally reducing or eliminating microscopic surface and subsurface defects, and increasing the microhardness of the surface layer. It has been estimated that if smoothing tools of this type were used in conjunction with cutting tools on sufficiently precise lathes, it would be possible to reduce the roughness of machined surfaces to as little as 3 nm. A tool according to the proposal would consist of a smoothing insert in a metal holder. The smoothing insert would be made from a diamond/metal functionally graded composite rod preform, which, in turn, would be made by sintering together a bulk single-crystal or polycrystalline diamond, a diamond powder, and a metallic alloy at high pressure. To form the spherical smoothing tip, the diamond end of the preform would be subjected to flat grinding, conical grinding, spherical grinding using diamond wheels, and finally spherical polishing and/or buffing using diamond powders. If the diamond were a single crystal, then it would be crystallographically oriented, relative to the machining motion, to minimize its wear and maximize its hardness. Spherically polished diamonds could also be useful for purposes other than smoothing in finish machining: They would likely also be suitable for use as heat-resistant, wear-resistant, unlubricated sliding-fit bearing inserts.

  5. Diamond tool machining of materials which react with diamond

    DOEpatents

    Lundin, Ralph L.; Stewart, Delbert D.; Evans, Christopher J.

    1992-01-01

    Apparatus for the diamond machining of materials which detrimentally react with diamond cutting tools in which the cutting tool and the workpiece are chilled to very low temperatures. This chilling halts or retards the chemical reaction between the workpiece and the diamond cutting tool so that wear rates of the diamond tool on previously detrimental materials are comparable with the diamond turning of materials which do not react with diamond.

  6. Diamond tool machining of materials which react with diamond

    DOEpatents

    Lundin, R.L.; Stewart, D.D.; Evans, C.J.

    1992-04-14

    An apparatus is described for the diamond machining of materials which detrimentally react with diamond cutting tools in which the cutting tool and the workpiece are chilled to very low temperatures. This chilling halts or retards the chemical reaction between the workpiece and the diamond cutting tool so that wear rates of the diamond tool on previously detrimental materials are comparable with the diamond turning of materials which do not react with diamond. 1 figs.

  7. Method for machining steel with diamond tools

    DOEpatents

    Casstevens, John M.

    1986-01-01

    The present invention is directed to a method for machining optical quality inishes and contour accuracies of workpieces of carbon-containing metals such as steel with diamond tooling. The wear rate of the diamond tooling is significantly reduced by saturating the atmosphere at the interface of the workpiece and the diamond tool with a gaseous hydrocarbon during the machining operation. The presence of the gaseous hydrocarbon effectively eliminates the deterioration of the diamond tool by inhibiting or preventing the conversion of the diamond carbon to graphite carbon at the point of contact between the cutting tool and the workpiece.

  8. Method for machining steel with diamond tools

    DOEpatents

    Casstevens, J.M.

    1984-01-01

    The present invention is directed to a method for machine optical quality finishes and contour accuracies of workpieces of carbon-containing metals such as steel with diamond tooling. The wear rate of the diamond tooling is significantly reduced by saturating the atmosphere at the interface of the workpiece and the diamond tool with a gaseous hydrocarbon during the machining operation. The presence of the gaseous hydrocarbon effectively eliminates the deterioration of the diamond tool by inhibiting or preventing the conversion of the diamond carbon to graphite carbon at the point of contact between the cutting tool and the workpiece.

  9. Abrasivity Assessment of Granitic Building Stones in Relation to Diamond Tool Wear Rate Using Mineralogy-Based Rock Hardness Indexes

    NASA Astrophysics Data System (ADS)

    Yılmaz, Nurdan Güneş

    2011-11-01

    The objective of the present study was to determine the abrasive wear potential of granites in circular sawing using some mineralogy-based rock hardness indexes. A literature study indicated that little or no attention has been given to assessing this kind of relationship in the field of stone processing. To accomplish this objective, sawing experiments were performed on nine different granites used widely as building and decorative stone materials. The measured sawblade-specific wear rates were correlated with three different rock hardness indexes attained by combining the percentage content of hard mineral constituents with their known hardness values. Statistical analysis of the experimental data revealed that rock hardness indexes that are based on both Vickers hardness number and Rosiwal hardness could be accepted as reliable indicators of granite abrasivity. These two indexes were also found to correlate well with the average power drawn during the process. However, the rock abrasivity index based on Mohs relative scratch hardness did not show statistically significant correlations with sawblade wear rate and power drawn. Although quartz percentage content is regarded as an important abrasivity parameter by practitioners, the observations made here indicate that consideration of quartz percentage content alone is not sufficient to describe the abrasive potential of granites, and thus incorporation of other hard mineral constituents could be more suitable.

  10. Novel diamond-coated tools for dental drilling applications.

    PubMed

    Jackson, M J; Sein, H; Ahmed, W; Woodwards, R

    2007-01-01

    The application of diamond coatings on cemented tungsten carbide (WC-Co) tools has been the subject of much attention in recent years in order to improve cutting performance and tool life in orthodontic applications. WC-Co tools containing 6% Co metal and 94% WC substrate with an average grain size of 1 - 3 microm were used in this study. In order to improve the adhesion between diamond and WC substrates it is necessary to etch cobalt from the surface and prepare it for subsequent diamond growth. Alternatively, a titanium nitride (TiN) interlayer can be used prior to diamond deposition. Hot filament chemical vapour deposition (HFCVD) with a modified vertical filament arrangement has been employed for the deposition of diamond films to TiN and etched WC substrates. Diamond film quality and purity has been characterized using scanning electron microscopy (SEM) and micro Raman spectroscopy. The performances of diamond-coated WC-Co tools, uncoated WC-Co tools, and diamond embedded (sintered) tools have been compared by drilling a series of holes into various materials such as human tooth, borosilicate glass, and acrylic tooth materials. Flank wear has been used to assess the wear rates of the tools when machining biomedical materials such as those described above. It is shown that using an interlayer such as TiN prior to diamond deposition provides the best surface preparation for producing dental tools.

  11. Novel diamond-coated tools for dental drilling applications.

    PubMed

    Jackson, M J; Sein, H; Ahmed, W; Woodwards, R

    2007-01-01

    The application of diamond coatings on cemented tungsten carbide (WC-Co) tools has been the subject of much attention in recent years in order to improve cutting performance and tool life in orthodontic applications. WC-Co tools containing 6% Co metal and 94% WC substrate with an average grain size of 1 - 3 microm were used in this study. In order to improve the adhesion between diamond and WC substrates it is necessary to etch cobalt from the surface and prepare it for subsequent diamond growth. Alternatively, a titanium nitride (TiN) interlayer can be used prior to diamond deposition. Hot filament chemical vapour deposition (HFCVD) with a modified vertical filament arrangement has been employed for the deposition of diamond films to TiN and etched WC substrates. Diamond film quality and purity has been characterized using scanning electron microscopy (SEM) and micro Raman spectroscopy. The performances of diamond-coated WC-Co tools, uncoated WC-Co tools, and diamond embedded (sintered) tools have been compared by drilling a series of holes into various materials such as human tooth, borosilicate glass, and acrylic tooth materials. Flank wear has been used to assess the wear rates of the tools when machining biomedical materials such as those described above. It is shown that using an interlayer such as TiN prior to diamond deposition provides the best surface preparation for producing dental tools. PMID:17365432

  12. Analysis of the influence of tool dynamics in diamond turning

    SciTech Connect

    Fawcett, S.C.; Luttrell, D.E.; Keltie, R.F.

    1988-12-01

    This report describes the progress in defining the role of machine and interface dynamics on the surface finish in diamond turning. It contains a review of literature from conventional and diamond machining processes relating tool dynamics, material interactions and tool wear to surface finish. Data from experimental measurements of tool/work piece interface dynamics are presented as well as machine dynamics for the DTM at the Center.

  13. Friction and wear of plasma-deposited diamond films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wu, Richard L. C.; Garscadden, Alan; Barnes, Paul N.; Jackson, Howard E.

    1993-01-01

    Reciprocating sliding friction experiments in humid air and in dry nitrogen and unidirectional sliding friction experiments in ultrahigh vacuum were conducted with a natural diamond pin in contact with microwave-plasma-deposited diamond films. Diamond films with a surface roughness (R rms) ranging from 15 to 160 nm were produced by microwave-plasma-assisted chemical vapor deposition. In humid air and in dry nitrogen, abrasion occurred when the diamond pin made grooves in the surfaces of diamond films, and thus the initial coefficients of friction increased with increasing initial surface roughness. The equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. In vacuum the friction for diamond films contacting a diamond pin arose primarily from adhesion between the sliding surfaces. In these cases, the initial and equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. The equilibrium coefficients of friction were 0.02 to 0.04 in humid air and in dry nitrogen, but 1.5 to 1.8 in vacuum. The wear factor of the diamond films depended on the initial surface roughness, regardless of environment; it increased with increasing initial surface roughness. The wear factors were considerably higher in vacuum than in humid air and in dry nitrogen.

  14. Forty years of development in diamond tools

    NASA Astrophysics Data System (ADS)

    The growth of the diamond industry in Western Countries since the First World War is surveyed. The articles described deal specifically with the development of the industrial diamond and diamond tool sector in different countries. All data point to continuing rapid expansion in the diamond tool sector. The West consumes 80 percent of world industrial diamond production. Diamond consumption increased sharply in the U.S. during World War 2. There are 300 diamond manufacturers in the U.S. today. In 1940, there were 25. In Japan, consumption of industrial diamonds has increased several times. In Italy, there has been a 75 fold increase in the production of diamond tools since 1959.

  15. Wear-Resistant, Self-Lubricating Surfaces of Diamond Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1995-01-01

    In humid air and dry nitrogen, as-deposited, fine-grain diamond films and polished, coarse-grain diamond films have low steady-state coefficients of friction (less than 0.1) and low wear rates (less than or equal to 10(exp -6) mm(exp 3)/N-m). In an ultrahigh vacuum (10(exp -7) Pa), however, they have high steady-state coefficients of friction (greater than 0.6) and high wear rates (greater than or equal to 10(exp -4) mm(exp 3)/N-m). Therefore, the use of as-deposited, fine-grain and polished, coarse-grain diamond films as wear-resistant, self-lubricating coatings must be limited to normal air or gaseous environments such as dry nitrogen. On the other hand, carbon-ion-implanted, fine-grain diamond films and nitrogen-ion-implanted, coarse-grain diamond films have low steady-state coefficients of friction (less than 0.1) and low wear rates (less than or equal to 10(exp -6) mm(exp 3)/N-m) in all three environments. These films can be effectively used as wear-resistant, self-lubricating coatings in an ultrahigh vacuum as well as in normal air and dry nitrogen.

  16. Diamond wheel wear sensing with acoustic emission --wheel wear mechanisms and the effects of process variables

    SciTech Connect

    Tang, Jianshe; Dornfeld, D.; Syoji, Katsuo

    1996-12-31

    The wear of diamond wheels has significant influence on the surface finish of ground ceramics and the resulting subsurface fracture damage. For optimization and control of the grinding process it is necessary to monitor the wear states of the grinding wheels. A project on diamond wheel wear sensing with acoustic emission was started recently in the Laboratory of Manufacturing Automation at the University of California at Berkeley. The main aims of the project are: (a) to identify the possible wheel wear patterns at different combinations of bond materials, grits, and grinding conditions; (b) to develop suitable AE signal processing methods to extract the AE features to represent the wheel wear characteristics, and establish a strategy for using AE for in-process monitoring of diamond wheel wear in grinding of ceramics. This paper presents the results of part of the project. It mainly focuses on the diamond wheel wear mechanisms, the effects of process variables including basic wheel elements and grinding parameters, and the relationship with AErms and AE frequency content.

  17. Cylindrical Wire Electrical Discharge Machining of Metal Bond Diamond Wheels- Part II: Wheel Wear Mechanism

    SciTech Connect

    McSpadden, SB

    2002-01-22

    The use of stereo scanning Electron Microscopy (SEM) to investigate the wear mechanism of the wire EDM true metal bond diamond wheel for ceramic grinding is presented. On the grinding wheel, a wedge-shape removal part was machined to enable the examination and measurement of the worn wheel surfaces using the stereo SEM. The stereo SEM was calibrated by comparing results of depth profile of a wear groove with the profilometer measurements. On the surface of the grinding wheel after wire EDM truing and before grinding, the diamond protruding heights were measured in the level of 35 {micro}m, comparing to the 54 {micro}m average size of the diamond in the grinding wheel. The gap between the EDM wire and rotating grinding wheel is estimated to be about 35 to 40 {micro}m. This observation indicates that, during the wire EDM, electrical sparks occur between the metal bond and EDM wire, which leaves the diamond protruding in the gap between the wire and wheel. The protruding diamond is immediately fractured at the start of the grinding process, even under a light grinding condition. After heavy grinding, the grinding wheel surface and the diamond protrusion heights are also investigated using the stereo SEM. The height of diamond protrusion was estimated in the 5 to 15 {micro}m range. This study has demonstrated the use of stereo SEM as a metrology tool to study the grinding wheel surface.

  18. Modeling and Tool Wear in Routing of CFRP

    SciTech Connect

    Iliescu, D.; Fernandez, A.; Gutierrez-Orrantia, M. E.; Lopez de Lacalle, L. N.

    2011-01-17

    This paper presents the prediction and evaluation of feed force in routing of carbon composite material. In order to extend tool life and improve quality of the machined surface, a better understanding of uncoated and coated tool behaviors is required. This work describes (1) the optimization of the geometry of multiple teeth tools minimizing the tool wear and the feed force, (2) the optimization of tool coating and (3) the development of a phenomenological model between the feed force, the routing parameters and the tool wear. The experimental results indicate that the feed rate, the cutting speed and the tool wear are the most significant factors affecting the feed force. In the case of multiple teeth tools, a particular geometry with 14 teeth right helix right cut and 11 teeth left helix right cut gives the best results. A thick AlTiN coating or a diamond coating can dramatically improve the tool life while minimizing the axial force, roughness and delamination. A wear model has then been developed based on an abrasive behavior of the tool. The model links the feed rate to the tool geometry parameters (tool diameter), to the process parameters (feed rate, cutting speed and depth of cut) and to the wear. The model presented has been verified by experimental tests.

  19. A new design of tungsten carbide tools with diamond coatings

    SciTech Connect

    Weihnacht, V.; Fan, W.D.; Jagannadham, K.; Narayan, J.; Liu, C.

    1996-09-01

    We have designed tungsten carbide tools with a new binder, which makes them suitable for advanced diamond tool coatings. The new tool substrates, made of tungsten carbide and nickel aluminide as binder phase, are produced by sintering and hot isostatic pressing, and also by combustion synthesis. The high temperature strength of nickel aluminide is key to superior tool performance at elevated temperatures. More importantly, nickel aluminides reduce the formation of graphite and promote diamond growth during chemical vapor deposition. Diamond films are deposited on the new tool substrates to investigate the nucleation density, adhesion, and wear resistance. The diamond coatings are characterized by scanning electron microscopy and Raman spectroscopy. The graphitizing tendency due to cobalt in the tungsten carbide tools was found to be a limitation to improve adhesion of diamond films. The new tool substrates with nickel aluminide binder have been found to exhibit good adhesion and wear resistance. The implications of these results in advanced cutting tools are discussed. {copyright} {ital 1996 Materials Research Society.}

  20. A new methodology for predictive tool wear

    NASA Astrophysics Data System (ADS)

    Kim, Won-Sik

    An empirical approach to tool wear, which requires a series of machining tests for each combination of insert and work material, has been a standard practice for industries since early part of the twentieth century. With many varieties of inserts and work materials available for machining, the empirical approach is too experiment-intensive that the demand for the development of a model-based approach is increasing. With a model-based approach, the developed wear equation can be extended without additional machining experiments. The main idea is that the temperatures on the primary wear areas are increasing such that the physical properties of the tool material degrade substantially and consequently tool wear increases. Dissolution and abrasion are identified to be the main mechanisms for tool wear. Flank wear is predominantly a phenomenon of abrasion as evident by the presence of a scoring mark on the flank surface. Based on this statement, it is reasonable to expect that the flank-wear rate would increase with the content of hard inclusions. However, experimental flank wear results did not necessary correspond to the content of cementite phase present in the steels. Hence, other phenomena are believed to significantly affect wear behavior under certain conditions. When the cutting temperature in the flank interface is subjected to high enough temperatures, pearlitic structure austenizes. During the formation of a new austenitic phase, the existing carbon is dissolved into the ferrite matrix, which will reduce the abrasive action. To verify the austenitic transformation, turning tests were conducted with plain carbon steels. The machined surface areas are imaged using X-ray diffraction the Scanning Electron Microscope (SEM) and the Transmission Electron Microscope (TEM). On the other hand, crater wear occurs as a result of dissolution wear and abrasive wear. To verify the wear mechanisms of crater wear, various coating inserts as well as uncoated inserts were

  1. Defect characterization in the diamond cutting tools

    SciTech Connect

    Zeren, Muzaffer . E-mail: zeren@kou.edu.tr; Karagoez, Sadi

    2006-08-15

    In this study, a general defect characterization in the diamond cutting tools used in natural stone cutting has been investigated. Transverse rupture tests were carried out with different matrix and diamond compositions. In these defect characterization studies on diamond cutting tool materials various microstructural analyses were performed using the techniques of light microscopy (LM), scanning electron microscopy (SEM), energy-dispersed X-ray spectrography (EDX) and image analysis (IA)

  2. Wear mechanisms for polycrystalline-diamond compacts as utilized for drilling in geothermal environments. Final report

    SciTech Connect

    Hibbs, L.E. Jr.; Sogoian, G.C.

    1983-05-01

    The work, which was performed in the period from 12/6/79 to 9/30/81 included: (1) rock cutting experiments with single point polycrystalline sintered diamond compact (PDC) cutters to quantitatively determine cutter wear rates and identify wear modes, (2) PDC rock cutting experiments to measure temperatures developed and examine the effects of tool wear, cutting parameters and coolant flow rates on temperature generation, (3) assisting in performing full scale laboratory drilling experiments with PDC bits, using preheated air to simulate geothermal drilling conditions, and in analyzing and reporting the experimental results, and (4) acting in a consulting role with the purpose of establishing design specifications for geothermal hard matrix PDC bits to be procured by Sandia Laboratories for test purposes.

  3. Environmental effects on friction and wear of diamond and diamondlike carbon coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wu, Richard L. C.; Garscadden, Alan

    1992-01-01

    Reciprocating sliding friction experiments were conducted with a natural diamond flat, diamond film, and low and high density diamondlike carbon (DLC) films in contact with pin specimens of natural diamond and silicon nitride (Si3N4) both in humid air and dry air nitrogen. The results indicated that for natural diamond pin contacts the diamond films and the natural diamond flat were not susceptible to moisture but that moisture could increase both the coefficient of friction and the wear factors of the DLC films. The coefficients of friction and wear factors of the diamond films were generally similar to those of the natural diamond flat both in humid air and dry air nitrogen. In dry nitrogen the coefficients of friction of the high density DLC films in contact with pin specimens of both diamond and Si3N4 were generally low (about 0.02) and similar to those of the natural diamond flat and the diamond films. The wear factors of the materials in contact with both natural diamond and Si3N4 were generally in the ascending order of natural diamond flat, diamond film, high density DLC film, and low density DLC film. The moisture in the environment increased the coefficients of friction for Si3N4 pins in contact with all the materials. This increase in friction is due to the silicon oxide film produced on the surface of Si3N4 pins in humid air.

  4. Surface Design and Engineering Toward Wear-Resistant, Self-Lubricating Diamond Films and Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    The tribological properties of chemical-vapor-deposited (CVD) diamond films vary with the environment, possessing a Jekyll-and-Hyde character. CVD diamond has low coefficient of friction and high wear resistance in air but high coefficient of friction and low wear resistance in vacuum. Improving the tribological functionality of materials (such as achieving low friction and good wear resistance) was an aim of this investigation. Three studies on the surface design, surface engineering, and tribology of CVD diamond have shown that its friction and wear are significantly reduced in ultrahigh vacuum. The main criteria for judging whether diamond films are an effective wear-resistant, self-lubricating material were coefficient of friction and wear rate, which must be less than 0.1 and on the order of 10(exp 6) cu mm/N(dot)m, respectively. In the first study the presence of a thin film (less than 1 micron thick) of amorphous, nondiamond carbon (hydrogenated carbon, also called diamondlike carbon or DLC) on CVD diamond greatly decreased the coefficient of friction and the wear rate. Therefore, a thin DLC film on CVD diamond can be an effective wear-resistant, lubricating coating in ultrahigh vacuum. In the second study the presence of an amorphous, nondiamond carbon surface layer formed on CVD diamond by ion implantation significantly reduced the coefficient of friction and the wear rate in ultrahigh vacuum. Therefore, such surface layers are acceptable for effective self-lubricating, wear-resistant applications of CVD diamond. In the third study CVD diamond in contact with cubic boron nitride exhibited low coefficient of friction in ultra high vacuum. Therefore, this materials combination can provide an effective self-lubricating, wear-resistant couple in ultrahigh vacuum.

  5. Friction and Wear Properties of As-deposited and Carbon Ion-implanted Diamond Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1994-01-01

    Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 ke V ion energy, resulting in a dose of 1.2310(exp 17) carbon ions/cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40 percent relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and were properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to 10(exp -8)mm(exp 3)/N-m) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4)mm(exp 3/N-m) in ultrahigh vacuum. The carbon ion implanation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, nondiamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine- and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7)mm(exp 3/N-m). Even in ultrahigh vacuum, the presence of the nondiamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6)mm(exp 3)/N-m. Thus, the carbon ion-implanted, fine

  6. Friction and Wear Properties of As-Deposited and Carbon Ion-Implanted Diamond Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1996-01-01

    Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 keV ion energy, resulting in a dose of 1.2 x 10(exp 17) carbon ions per cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40% relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and wear properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to lO(exp -8) mm(exp 3) N(exp -1) m(exp -1)) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4) mm(exp 7) N(exp -1) m(exp -1)) in ultrahigh vacuum. The carbon ion implantation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, non-diamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7) mm(exp 3) N(exp -1) m(exp-1)). Even in ultrahigh vacuum, the presence of the non-diamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6

  7. Diamond and diamondlike carbon as wear-resistant, self-lubricating coatings for silicon nitride

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1995-01-01

    Recent work on the friction and wear properties of as-deposited fine-grain diamond, polished coarse-grain diamond, and as-deposited diamondlike carbon (DLC) films in humid air at a relative humidity of approximately 40 percent and in dry nitrogen is reviewed. Two types of chemical vapor deposition (CVD) processes are used to deposit diamond films on silicon nitride (Si3N4) substrates: microwave-plasma and hot-filament. Ion beams are used to deposit DLC films of Si3N4 substrates. The diamond and DLC films in sliding contact with hemispherical bare Si3N4 pins have low steady-state coefficients of friction (less than 0.2) and low wear rates (less than 10(exp -7) mm(exp 2)/N-m), and thus, can be used effectively as wear-resistant, self-lubricating coatings for Si3N4 in the aforementioned two environments.

  8. Self-Lubricating, Wear-Resistant Diamond Films Developed for Use in Vacuum Environment

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Diamond's outstanding properties--extreme hardness, chemical and thermal inertness, and high strength and rigidity--make it an ideal material for many tribological applications, such as the bearings, valves, and engine parts in the harsh environment found in internal-combustion engines, jet engines, and space propulsion systems. It has been demonstrated that chemical-vapor-deposited diamond films have low coefficients of friction (on the order of 0.01) and low wear rates (less than 10(sup -7) mm (sup 3/N-m)) both in humid air and dry nitrogen but that they have both high coefficients of friction (greater than 0.4) and high wear rates (on the order of 1(sup -4) mm sup 3/N-m)) in vacuum. It is clear that surface modifications that provide acceptable levels of friction and wear properties will be necessary before diamond films can be used for tribological applications in a space-like, vacuum environment. Previously, it was found that coatings of amorphous, non-diamond carbon can provide low friction in vacuum. Therefore, to reduce the friction and wear of diamond film in vacuum, carbon ions were implanted in an attempt to form a surface layer of amorphous carbon phases on the diamond films.

  9. Optical wear assessment system for grinding tools

    NASA Astrophysics Data System (ADS)

    Heger, Thomas; Pandit, Madhukar C.

    2003-04-01

    The inspection and monitoring of the wear of grinding tools is essential in order to ensure the quality of the grinding tool and the finished product. Present methods rely on dismounting the grinding tool for examination of the grinding tool surface. Often, the state of the grinding tool surface is checked indirectly by evaluating the quality of the workpiece. The application of image processing which offers an effective means for in situ inspection and monitoring is described in the paper. By using multi-directional illumination and image fusion, an image with a high degree of relevant information is generated that is then segmented using the wavelet transform (MSA) and classified to distinguish grains and cavities. Results of the application of the algorithms for a high performance grinding wheel with CBN grains embedded in a resin base are presented.

  10. Diamond machine tool face lapping machine

    DOEpatents

    Yetter, H.H.

    1985-05-06

    An apparatus for shaping, sharpening and polishing diamond-tipped single-point machine tools. The isolation of a rotating grinding wheel from its driving apparatus using an air bearing and causing the tool to be shaped, polished or sharpened to be moved across the surface of the grinding wheel so that it does not remain at one radius for more than a single rotation of the grinding wheel has been found to readily result in machine tools of a quality which can only be obtained by the most tedious and costly processing procedures, and previously unattainable by simple lapping techniques.

  11. Preventing nanoscale wear of atomic force microscopy tips through the use of monolithic ultrananocrystalline diamond probes.

    PubMed

    Liu, J; Grierson, D S; Moldovan, N; Notbohm, J; Li, S; Jaroenapibal, P; O'Connor, S D; Sumant, A V; Neelakantan, N; Carlisle, J A; Turner, K T; Carpick, R W

    2010-05-21

    Nanoscale wear is a key limitation of conventional atomic force microscopy (AFM) probes that results in decreased resolution, accuracy, and reproducibility in probe-based imaging, writing, measurement, and nanomanufacturing applications. Diamond is potentially an ideal probe material due to its unrivaled hardness and stiffness, its low friction and wear, and its chemical inertness. However, the manufacture of monolithic diamond probes with consistently shaped small-radius tips has not been previously achieved. The first wafer-level fabrication of monolithic ultrananocrystalline diamond (UNCD) probes with <5-nm grain sizes and smooth tips with radii of 30-40 nm is reported, which are obtained through a combination of microfabrication and hot-filament chemical vapor deposition. Their nanoscale wear resistance under contact-mode scanning conditions is compared with that of conventional silicon nitride (SiN(x)) probes of similar geometry at two different relative humidity levels (approximately 15 and approximately 70%). While SiN(x) probes exhibit significant wear that further increases with humidity, UNCD probes show little measurable wear. The only significant degradation of the UNCD probes observed in one case is associated with removal of the initial seed layer of the UNCD film. The results show the potential of a new material for AFM probes and demonstrate a systematic approach to studying wear at the nanoscale.

  12. Surface Design and Engineering Toward Wear-Resistant, Self-Lubricant Diamond Films and Coatings. Chapter 10

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    This chapter describes three studies on the surface design, surface engineering, and tribology of chemical-vapor-deposited (CVD) diamond films and coatings toward wear-resistant, self-lubricating diamond films and coatings. Friction mechanisms and solid lubrication mechanisms of CVD diamond are stated. Effects of an amorphous hydrogenated carbon on CVD diamond, an amorphous, nondiamond carbon surface layer formed on CVD diamond by carbon and nitrogen ion implantation, and a materials combination of cubic boron nitride and CVD diamond on the adhesion, friction, and wear behaviors of CVD diamond in ultrahigh vacuum are described. How surface modification and the selected materials couple improved the tribological functionality of coatings, giving low coefficient of friction and good wear resistance, is explained.

  13. Performance evaluation of bound diamond ring tools

    SciTech Connect

    Piscotty, M.A.; Taylor, J.S.; Blaedel, K.L.

    1995-07-14

    LLNL is collaborating with the Center for Optics Manufacturing (COM) and the American Precision Optics Manufacturers Association (APOMA) to optimize bound diamond ring tools for the spherical generation of high quality optical surfaces. An important element of this work is establishing an experimentally-verified link between tooling properties and workpiece quality indicators such as roughness, subsurface damage and removal rate. In this paper, we report on a standardized methodology for assessing ring tool performance and its preliminary application to a set of commercially-available wheels. Our goals are to (1) assist optics manufacturers (users of the ring tools) in evaluating tools and in assessing their applicability for a given operation, and (2) provide performance feedback to wheel manufacturers to help optimize tooling for the optics industry. Our paper includes measurements of wheel performance for three 2-4 micron diamond bronze-bond wheels that were supplied by different manufacturers to nominally- identical specifications. Preliminary data suggests that the difference in performance levels among the wheels were small.

  14. Measurement of tool forces in diamond turning

    SciTech Connect

    Drescher, J.; Dow, T.A.

    1988-12-01

    A dynamometer has been designed and built to measure forces in diamond turning. The design includes a 3-component, piezoelectric transducer. Initial experiments with this dynamometer system included verification of its predicted dynamic characteristics as well as a detailed study of cutting parameters. Many cutting experiments have been conducted on OFHC Copper and 6061-T6 Aluminum. Tests have involved investigation of velocity effects, and the effects of depth and feedrate on tool forces. Velocity has been determined to have negligible effects between 4 and 21 m/s. Forces generally increase with increasing depth of cut. Increasing feedrate does not necessarily lead to higher forces. Results suggest that a simple model may not be sufficient to describe the forces produced in the diamond turning process.

  15. Smooth diamond films as low friction, long wear surfaces

    DOEpatents

    Gruen, Dieter M.; Krauss, Alan R.; Erdemir, Ali; Bindal, Cuma; Zuiker, Christopher D.

    1999-01-01

    An article and method of manufacture of a nanocrystalline diamond film. The nanocrystalline film is prepared by forming a carbonaceous vapor, providing an inert gas containing gas stream and combining the gas stream with the carbonaceous containing vapor. A plasma of the combined vapor and gas stream is formed in a chamber and fragmented carbon species are deposited onto a substrate to form the nanocrystalline diamond film having a root mean square flatness of about 50 nm deviation from flatness in the as deposited state.

  16. The use of analytical surface tools in the fundamental study of wear. [atomic nature of wear

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1977-01-01

    Various techniques and surface tools available for the study of the atomic nature of the wear of materials are reviewed These include chemical etching, x-ray diffraction, electron diffraction, scanning electron microscopy, low-energy electron diffraction, Auger emission spectroscopy analysis, electron spectroscopy for chemical analysis, field ion microscopy, and the atom probe. Properties of the surface and wear surface regions which affect wear, such as surface energy, crystal structure, crystallographic orientation, mode of dislocation behavior, and cohesive binding, are discussed. A number of mechanisms involved in the generation of wear particles are identified with the aid of the aforementioned tools.

  17. Friction and Wear of Ion-Beam-Deposited Diamondlike Carbon on Chemical-Vapor-Deposited, Fine-Grain Diamond

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wu, Richard L. C.; Lanter, William C.

    1996-01-01

    Friction and wear behavior of ion-beam-deposited diamondlike carbon (DLC) films coated on chemical-vapor-deposited (CVD), fine-grain diamond coatings were examined in ultrahigh vacuum, dry nitrogen, and humid air environments. The DLC films were produced by the direct impact of an ion beam (composed of a 3:17 mixture of Ar and CH4) at ion energies of 1500 and 700 eV and an RF power of 99 W. Sliding friction experiments were conducted with hemispherical CVD diamond pins sliding on four different carbon-base coating systems: DLC films on CVD diamond; DLC films on silicon; as-deposited, fine-grain CVD diamond; and carbon-ion-implanted, fine-grain CVD diamond on silicon. Results indicate that in ultrahigh vacuum the ion-beam-deposited DLC films on fine-grain CVD diamond (similar to the ion-implanted CVD diamond) greatly decrease both the friction and wear of fine-grain CVD diamond films and provide solid lubrication. In dry nitrogen and in humid air, ion-beam-deposited DLC films on fine-grain CVD diamond films also had a low steady-state coefficient of friction and a low wear rate. These tribological performance benefits, coupled with a wider range of coating thicknesses, led to longer endurance life and improved wear resistance for the DLC deposited on fine-grain CVD diamond in comparison to the ion-implanted diamond films. Thus, DLC deposited on fine-grain CVD diamond films can be an effective wear-resistant, lubricating coating regardless of environment.

  18. Prediction Of Abrasive And Diffusive Tool Wear Mechanisms In Machining

    NASA Astrophysics Data System (ADS)

    Rizzuti, S.; Umbrello, D.

    2011-01-01

    Tool wear prediction is regarded as very important task in order to maximize tool performance, minimize cutting costs and improve the quality of workpiece in cutting. In this research work, an experimental campaign was carried out at the varying of cutting conditions with the aim to measure both crater and flank tool wear, during machining of an AISI 1045 with an uncoated carbide tool P40. Parallel a FEM-based analysis was developed in order to study the tool wear mechanisms, taking also into account the influence of the cutting conditions and the temperature reached on the tool surfaces. The results show that, when the temperature of the tool rake surface is lower than the activation temperature of the diffusive phenomenon, the wear rate can be estimated applying an abrasive model. In contrast, in the tool area where the temperature is higher than the diffusive activation temperature, the wear rate can be evaluated applying a diffusive model. Finally, for a temperature ranges within the above cited values an adopted abrasive-diffusive wear model furnished the possibility to correctly evaluate the tool wear phenomena.

  19. Tool wear in turning of titanium alloy after thermohydrogen treatment

    NASA Astrophysics Data System (ADS)

    Wei, Weihua; Xu, Jiuhua; Fu, Yucan; Yang, Shubao

    2012-07-01

    The influence of hydrogen contents on the tool wear has been mainly focused on the flank wear of the common tool, and the influence of hydrogen contents on the rake crater wear (main wear type) of the tool, particularly for the fine granular material tool, has been less investigated comprehensively. In this paper, for the purpose of researching the influence of hydrogen contents on tool wear, the titanium alloy Ti-6Al-4V is hydrogenated at 800 °C by thermohydrogen treatment technology and the turning experiments are carried out by applying uncoated WC-Co cemented carbide tool. The three-dimensional video microscope is used to take photos and measure tool wear. The results show that both of crater wear depth ( K T) and average flank wear width ( V B) firstly decreases and then increases with the increasing of hydrogen content. The maximum reducing amplitude of K T and V B is about 50% and 55%, respectively. Under the given conditions, the optimum hydrogen content is 0.26%. It is considered that the reduction of cutting temperature is an important factor for improving tool wear after the Ti-6Al-4V alloy is properly hydrogenated. Furthermore, the reasons of hydrogen effect on the tool wear are chiefly attributed to comprehensive effect of hydrogen contents on microstructure, physical properties and dynamic mechanical properties of the Ti-6Al-4V alloy. The proposed research provides the basic data for evaluating the machinability of hydrogenation Ti-6Al-4V alloy, and promotes practical application of thermohydrogen treatment technology in titanium alloys.

  20. The High performance of nanocrystalline CVD diamond coated hip joints in wear simulator test.

    PubMed

    Maru, M M; Amaral, M; Rodrigues, S P; Santos, R; Gouvea, C P; Archanjo, B S; Trommer, R M; Oliveira, F J; Silva, R F; Achete, C A

    2015-09-01

    The superior biotribological performance of nanocrystalline diamond (NCD) coatings grown by a chemical vapor deposition (CVD) method was already shown to demonstrate high wear resistance in ball on plate experiments under physiological liquid lubrication. However, tests with a close-to-real approach were missing and this constitutes the aim of the present work. Hip joint wear simulator tests were performed with cups and heads made of silicon nitride coated with NCD of ~10 μm in thickness. Five million testing cycles (Mc) were run, which represent nearly five years of hip joint implant activity in a patient. For the wear analysis, gravimetry, profilometry, scanning electron microscopy and Raman spectroscopy techniques were used. After 0.5 Mc of wear test, truncation of the protruded regions of the NCD film happened as a result of a fine-scale abrasive wear mechanism, evolving to extensive plateau regions and highly polished surface condition (Ra<10nm). Such surface modification took place without any catastrophic features as cracking, grain pullouts or delamination of the coatings. A steady state volumetric wear rate of 0.02 mm(3)/Mc, equivalent to a linear wear of 0.27 μm/Mc favorably compares with the best performance reported in the literature for the fourth generation alumina ceramic (0.05 mm(3)/Mc). Also, squeaking, quite common phenomenon in hard-on-hard systems, was absent in the present all-NCD system.

  1. Crystallographic Anisotropy of Wear on a Polycrystalline Diamond Surface

    SciTech Connect

    El-dasher, B; Gray, J J; Tringe, J W; Wild, C; W?rner, E; Koidl, P; Biener, J; Hamza, A V

    2005-11-16

    We correlate topography and diffraction measurements to demonstrate that grain orientation profoundly influences polishing rates in polycrystalline diamond synthesized by chemical vapor deposition. Grains oriented with {l_brace}111{r_brace} or {l_brace}100{r_brace} planes perpendicular to the surface normal polish at significantly lower rates compared with grains of all other orientations when the surface is polished in continuously varying in-plane directions. These observations agree with predictions of the periodic bond chain vector model, developed previously for single crystals, and indicate that the polishing rate depends strongly on the number of PBC vectors that are within 10{sup o} of the exposed surface plane.

  2. Ultrananocrystalline diamond film as a wear resistant and protective coating for mechanical seal applications.

    SciTech Connect

    Sumant, A. V.; Krauss, A. R.; Gruen, D. M.; Auciello, O.; Erdemir, A.; Williams, M.; Artiles, A. F.; Adams, W.; Western Michigan Univ.; Flowserve Corp.

    2005-01-01

    Mechanical shaft seals used in pumps are critically important to the safe operation of the paper, pulp, and chemical process industry, as well as petroleum and nuclear power plants. Specifically, these seals prevent the leakage of toxic gases and hazardous chemicals to the environment and final products from the rotating equipment used in manufacturing processes. Diamond coatings have the potential to provide negligible wear, ultralow friction, and high corrosion resistance for the sliding surfaces of mechanical seals, because diamond exhibits outstanding tribological, physical, and chemical properties. However, diamond coatings produced by conventional chemical vapor deposition (CVD) exhibit high surface roughness (R{sub a} {>=} 1 {mu}m), which results in high wear of the seal counterface, leading to premature seal failure. To avoid this problem, we have developed an ultrananocrystalline diamond (UNCD) film formed by a unique CH{sub 4}/Ar microwave plasma CVD method. This method yields extremely smooth diamond coatings with surface roughness R{sub a} = 20-30 nm and an average grain size of 2-5 nm. We report the results of a systematic test program involving uncoated and UNCD-coated SiC shaft seals. Results confirmed that the UNCD-coated seals exhibited neither measurable wear nor any leakage during long-duration tests that took 21 days to complete. In addition, the UNCD coatings reduced the frictional torque for seal rotation by five to six times compared with the uncoated seals. This work promises to lead to rotating shaft seals with much improved service life, reduced maintenance cost, reduced leakage of environmentally hazardous materials, and increased energy savings. This technology may also have many other tribological applications involving rolling or sliding contacts.

  3. Ultra-high wear resistance of ultra-nanocrystalline diamond film: Correlation with microstructure and morphology

    NASA Astrophysics Data System (ADS)

    Rani, R.; Kumar, N.; Lin, I.-Nan

    2016-05-01

    Nanostructured diamond films are having numerous unique properties including superior tribological behavior which is promising for enhancing energy efficiency and life time of the sliding devices. High wear resistance is the principal criterion for the smooth functioning of any sliding device. Such properties are achievable by tailoring the grain size and grain boundary volume fraction in nanodiamond film. Ultra-nanocrystalline diamond (UNCD) film was attainable using optimized gas plasma condition in a microwave plasma enhanced chemical vapor deposition (MPECVD) system. Crystalline phase of ultra-nanodiamond grains with matrix phase of amorphous carbon and short range ordered graphite are encapsulated in nanowire shaped morphology. Film showed ultra-high wear resistance and frictional stability in micro-tribological contact conditions. The negligible wear of film at the beginning of the tribological contact was later transformed into the wearless regime for prolonged sliding cycles. Both surface roughness and high contact stress were the main reasons of wear at the beginning of sliding cycles. However, the interface gets smoothened due to continuous sliding, finally leaded to the wearless regime.

  4. Electron microscopic evidence for a tribologically induced phase transformation as the origin of wear in diamond

    SciTech Connect

    Zhang, Xinyi; Schneider, Reinhard; Müller, Erich; Gerthsen, Dagmar; Mee, Manuel; Meier, Sven; Gumbsch, Peter

    2014-02-14

    Tribological testing of a coarse-grained diamond layer, deposited by plasma-enhanced chemical vapor deposition, was performed on a ring-on-ring tribometer with a diamond counterpart. The origin of the wear of diamond and of the low friction coefficient of 0.15 was studied by analyzing the microstructure of worn and unworn regions by transmission and scanning electron microscopy. In the worn regions, the formation of an amorphous carbon layer with a thickness below 100 nm is observed. Electron energy loss spectroscopy of the C-K ionization edge reveals the transition from sp{sup 3}-hybridized C-atoms in crystalline diamond to a high fraction of sp{sup 2}-hybridized C-atoms in the tribo-induced amorphous C-layer within a transition region of less than 5 nm thickness. The mechanically induced phase transformation from diamond to the amorphous phase is found to be highly anisotropic which is clearly seen at a grain boundary, where the thickness of the amorphous layer above the two differently oriented grains abruptly changes.

  5. Numerical modelling of tool wear in turning with cemented carbide cutting tools

    SciTech Connect

    Franco, P.; Estrems, M.; Faura, F.

    2007-04-07

    A numerical model is proposed for analysing the flank and crater wear resulting from the loss of material on cutting tool surface in turning processes due to wear mechanisms of adhesion, abrasion and fracture. By means of this model, the material loss along cutting tool surface can be analysed, and the worn surface shape during the workpiece machining can be determined. The proposed model analyses the gradual degradation of cutting tool during turning operation, and tool wear can be estimated as a function of cutting time. Wear-land width (VB) and crater depth (KT) can be obtained for description of material loss on cutting tool surface, and the effects of the distinct wear mechanisms on surface shape can be studied. The parameters required for the tool wear model are obtained from bibliography and experimental observation for AISI 4340 steel turning with WC-Co cutting tools.

  6. Reducing tool wear when machining austenitic stainless steels

    SciTech Connect

    Magee, J.H.; Kosa, T.

    1998-07-01

    Austenitic stainless steels are considered more difficult to machine than carbon steels due to their high work hardening rate, large spread between yield and ultimate tensile strength, high toughness and ductility, and low thermal conductivity. These characteristics can result in a built-up edge or excessive tool wear during machining, especially when the cutting speed is too high. The practical solution is to lower the cutting speed until tool life reaches an acceptable level. However, lower machining speed negatively impacts productivity. Thus, in order to overcome tool wear at relatively high machining speeds for these alloys, on-going research is being performed to improve cutting fluids, develop more wear-resistant tools, and to modify stainless steels to make them less likely to cause tool wear. This paper discusses compositional modifications to the two most commonly machined austenitic stainless steels (Type 303 and 304) which reduced their susceptibility to tool wear, and allowed these grades to be machined at higher cutting speeds.

  7. DIAMONDS: a new Bayesian nested sampling tool

    NASA Astrophysics Data System (ADS)

    Corsaro, Enrico; De Ridder, Joris

    2015-09-01

    In the context of high-quality asteroseismic data provided by the NASA Kepler Mission, we developed a new code, termed DIAMONDS (high-DImensional And multi-MOdal NesteD Sampling), for fast Bayesian parameter estimation and model comparison by means of the Nested Sampling Monte Carlo (NSMC) algorithm, an efficient and powerful method very suitable for high-dimensional problems (like the peak bagging analysis of solar-like oscillations) and multi-modal problems (i.e. problems that show multiple solutions). We applied the code to the peak bagging analysis of solar-like oscillations observed in a challenging F-type star. By means of DIAMONDS one is able to detect the different backgrounds in the power spectrum of the star (e.g. stellar granulation and faculae activity) and to understand whether one or two oscillation peaks can be identified or not. In addition, we demonstrate a novel approach to peak bagging based on multi-modality, which is able to reduce significantly the number of free parameters involved in the peak bagging model. This novel approach is therefore of great interest for possible future automatization of the entire analysis technique. Software package available at the DIAMONDS code website: http://https://fys.kuleuven.be/ster/Software/Diamonds/.

  8. Wear of tillage tools coated by thermoplastic coatings

    NASA Astrophysics Data System (ADS)

    Ali, Waheed Y.; Ezzat, Fawzy M. H.

    1994-04-01

    Experiments were carried out to investigate the abrasive wear of tillage tools caused by soil. Low-carbon steel and hardened steel specimens as well as specimens coated by thermoplastic composites were tested. Silicon oxide (SiO2), aluminium oxide (Al2O3), iron, copper and glass fibre were used as filling materials in polyamide (PA6) and polyethylene (PE) coatings. Low-carbon steel was used as substrate. An abrasive wear tester was constructed to simulate the operation of real tillage tools. The relative motion between the test specimens and soil was controlled. PA6 showed promising results, especially if both the concentration and grain size of the additives were carefully selected. The addition of iron and Al2O3 powders to PA6 showed a considerable mitigation in the wear process if their concentrations were controlled to a certain limit.

  9. Calculation of the Intensity of Adhesive-Fatigue Wear of Cutting Tools

    NASA Astrophysics Data System (ADS)

    Bibik, V.; Ivushkina, N.; Arhipova, D.

    2016-08-01

    On the base of kinetic equation of strength the authors suggest the method carbide tools wear intensity calculation allowing comparing wear resistance basing on tool material thermal diffusivity coefficient. The authors obtain equations of tool wear resistance dependences upon its thermal diffusivity which show close correlation between these parameters. The results of wear intensity calculations correspond well to the experimental results under the cutting rates corresponding to the region of adhesive-fatigue wear. The inserts with low thermal diffusivity coefficient are characterized by lower wear rate at the inial and normal stages of wear.

  10. An investigation of chatter and tool wear when machining titanium

    NASA Technical Reports Server (NTRS)

    Sutherland, I. A.

    1974-01-01

    The low thermal conductivity of titanium, together with the low contact area between chip and tool and the unusually high chip velocities, gives rise to high tool tip temperatures and accelerated tool wear. Machining speeds have to be considerably reduced to avoid these high temperatures with a consequential loss of productivity. Restoring this lost productivity involves increasing other machining variables, such as feed and depth-of-cut, and can lead to another machining problem commonly known as chatter. This work is to acquaint users with these problems, to examine the variables that may be encountered when machining a material like titanium, and to advise the machine tool user on how to maximize the output from the machines and tooling available to him. Recommendations are made on ways of improving tolerances, reducing machine tool instability or chatter, and improving productivity. New tool materials, tool coatings, and coolants are reviewed and their relevance examined when machining titanium.

  11. Modelling of Tool Wear and Residual Stress during Machining of AISI H13 Tool Steel

    NASA Astrophysics Data System (ADS)

    Outeiro, José C.; Umbrello, Domenico; Pina, José C.; Rizzuti, Stefania

    2007-05-01

    Residual stresses can enhance or impair the ability of a component to withstand loading conditions in service (fatigue, creep, stress corrosion cracking, etc.), depending on their nature: compressive or tensile, respectively. This poses enormous problems in structural assembly as this affects the structural integrity of the whole part. In addition, tool wear issues are of critical importance in manufacturing since these affect component quality, tool life and machining cost. Therefore, prediction and control of both tool wear and the residual stresses in machining are absolutely necessary. In this work, a two-dimensional Finite Element model using an implicit Lagrangian formulation with an automatic remeshing was applied to simulate the orthogonal cutting process of AISI H13 tool steel. To validate such model the predicted and experimentally measured chip geometry, cutting forces, temperatures, tool wear and residual stresses on the machined affected layers were compared. The proposed FE model allowed us to investigate the influence of tool geometry, cutting regime parameters and tool wear on residual stress distribution in the machined surface and subsurface of AISI H13 tool steel. The obtained results permit to conclude that in order to reduce the magnitude of surface residual stresses, the cutting speed should be increased, the uncut chip thickness (or feed) should be reduced and machining with honed tools having large cutting edge radii produce better results than chamfered tools. Moreover, increasing tool wear increases the magnitude of surface residual stresses.

  12. Mesenchymal stem cell interaction with ultra smooth nanostructured diamond for wear resistant orthopaedic implants

    PubMed Central

    Clem, William C.; Chowdhury, Shafiul; Catledge, Shane A.; Weimer, Jeffrey J.; Shaikh, Faheem M.; Hennessy, Kristin M.; Konovalov, Valery V.; Hill, Michael R.; Waterfeld, Alfred; Bellis, Susan L.; Vohra, Yogesh K.

    2008-01-01

    Ultra smooth nanostructured diamond (USND) can be applied to greatly increase the wear resistance of orthopaedic implants over conventional designs. Herein we describe surface modification techniques and cytocompatibility studies performed on this new material. We report that hydrogen (H) -terminated USND surfaces supported robust mesenchymal stem cell (MSC) adhesion and survival, while oxygen (O) and fluorine (F) -terminated surfaces resisted cell adhesion, indicating that USND can be modified to either promote or prevent cell/biomaterial interactions. Given the favorable cell response to H-terminated USND, this material was further compared with two commonly-used biocompatible metals, titanium alloy (Ti-6Al-4V) and cobalt chrome (CoCrMo). MSC adhesion and proliferation were significantly improved on USND compared with CoCrMo, although cell adhesion was greatest on Ti-6Al-4V. Comparable amounts of the proadhesive protein, fibronectin, were deposited from serum on the three substrates. Finally, MSCs were induced to undergo osteoblastic differentiation on the three materials, and deposition of a mineralized matrix was quantified. Similar amounts of mineral were deposited onto USND and CoCrMo, whereas mineral deposition was slightly higher on Ti-6Al-4V. When coupled with recently published wear studies, these in vitro results suggest that USND has the potential to reduce debris particle release from orthopaedic implants without compromising osseointegration. PMID:18490051

  13. Tool Wear Characteristics of Oil Palm Empty Fruit Bunch Particleboard

    NASA Astrophysics Data System (ADS)

    Ratnasingam, Jegatheswaran; Chew Tek, Tee; Farrokhpayam, Saied Reza

    A series of machining experiments on the Oil-Palm Empty Fruit Bunch (OPEFB) particleboard were carried out using a CNC router, to evaluate the tool wearing properties of the composite in comparison to the conventional wood-material particleboard. A single-fluted tungsten-carbide router bit (12 mm φ, 18 000 rpm), with a rake angle of 15° was used in this experiment, in which the depth of cut was 1.5 mm and feed speed was 4.5 m min-1. The router bit machined the edge of the board, moving along the full length before returning to repeat the cycle. The tool was examined for the extent of wear after complete failure had occurred. The result found that the wear pattern was similar in the oil-palm based particleboard and the wood-based particleboard, but the former was twice more abrasive compared to the latter. Microscopic examination of the cutter edge revealed greater incidence of micro-fracture when cutting the oil-palm based particleboard, indicating the presence of hard impurities in the composite. From an economic perspective, the tooling cost for machining oil-palm based particleboard is estimated to be twice of the cost for machining wood-based particleboard. This study shows that the machining properties of oil-palm based particleboard will be a primary concern, if the board is to find widespread application as a potential substitute for wood-based particleboard.

  14. Characterization of tribo-layer formed during sliding wear of SiC ball against nanocrystalline diamond coatings

    SciTech Connect

    Dumpala, Ravikumar; Kumar, N.; Samji, Sunil Kumar; Dash, S.; Ramamoorthy, B.; Ramachandra Rao, M.S.

    2014-09-15

    Tribo-layer formation and frictional characteristics of the SiC ball were studied with the sliding test against nanocrystalline diamond coating under atmospheric test conditions. Unsteady friction coefficients in the range of 0.04 to 0.1 were observed during the tribo-test. Friction and wear characteristics were found to be influenced by the formation of cohesive tribo-layer (thickness ∼ 1.3 μm) in the wear track of nanocrystalline diamond coating. Hardness of the tribo-layer was measured using nanoindentation technique and low hardness of ∼ 1.2 GPa was observed. The presence of silicon and oxygen in the tribo-layer was noticed by the energy dispersive spectroscopy mapping and the chemical states of the silicon were analyzed using X-ray photoelectron spectroscopy. Large amount of oxygen content in the tribo-layer indicated tribo-oxidation wear mechanism. - Highlights: • Sliding wear and friction characteristics of SiC were studied against NCD coating. • Silicon oxide tribo-layer formation was observed in the NCD coating wear track. • Low hardness 1.2 GPa of tribo-layer was measured using nanoindentation technique. • Chemical states of silicon were analyzed using X-ray photoelectron spectroscopy.

  15. Modeling of cumulative tool wear in machining metal matrix composites

    SciTech Connect

    Hung, N.P.; Tan, V.K.; Oon, B.E.

    1995-12-31

    Metal matrix composites (MMCs) are notoriously known for their low machinability because of the abrasive and brittle reinforcement. Although a near-net-shape product could be produced, finish machining is still required for the final shape and dimension. The classical Taylor`s tool life equation that relates tool life and cutting conditions has been traditionally used to study machinability. The turning operation is commonly used to investigate the machinability of a material; tedious and costly milling experiments have to be performed separately; while a facing test is not applicable for the Taylor`s model since the facing speed varies as the tool moves radially. Collecting intensive machining data for MMCs is often difficult because of the constraints on size, cost of the material, and the availability of sophisticated machine tools. A more flexible model and machinability testing technique are, therefore, sought. This study presents and verifies new models for turning, facing, and milling operations. Different cutting conditions were utilized to assess the machinability of MMCs reinforced with silicon carbide or alumina particles. Experimental data show that tool wear does not depend on the order of different cutting speeds since abrasion is the main wear mechanism. Correlation between data for turning, milling, and facing is presented. It is more economical to rank machinability using data for facing and then to convert the data for turning and milling, if required. Subsurface damages such as work-hardened and cracked matrix alloy, and fractured and delaminated particles are discussed.

  16. Technological Aspects of Forming the Surface Microrelief of Low-Wear Coatings after Electro-Diamond Grinding

    NASA Astrophysics Data System (ADS)

    Burov, V. G.; Yanpolskiy, V. V.; Rakhimyanov, K. Kh

    2016-04-01

    The results of electro-diamond grinding of coatings based on the WC25 powder material are presented in the paper. It is shown that after electro-diamond grinding of the WC25 coating, an obtained magnitude (Ra=2.02µm) of surface roughness doesn’t meet the qualifying standards to parts surface working in wear-out conditions. The forming of the obtained microrelief is probably connected to the features of electrochemical dissolution of the WC25 coating material in the electrolyte being used. Based on the polarization studies, it is revealed that the electrochemical dissolution character of the indicated coating in the water solution of 10%NaNO3 is determined by the dissolution character of cobalt (Co) component. The intensive cobalt (Co) dissolution during the electro-diamond grinding of the WC25 coating leads to the tungsten carbide chipping by the grinding disk particles that increases the roughness. One of the way to improve the surface quality of low-wear coatings after electro-diamond grinding is an introduction of an additional step in a technological process, carrying out with the switched off source of technological current. For realization of the process according to this scheme a technological dimension chain is made which takes into consideration the dissolution value of the most active coating composition element while the calculating of the operating dimensions of a detail.

  17. Communication research between working capacity of hard- alloy cutting tools and fractal dimension of their wear

    NASA Astrophysics Data System (ADS)

    Arefiev, K.; Nesterenko, V.; Daneykina, N.

    2016-06-01

    The results of communication research between the wear resistance of the K applicability hard-alloy cutting tools and the fractal dimension of the wear surface, which is formed on a back side of the cutting edge when processing the materials showing high adhesive activity are presented in the paper. It has been established that the wear resistance of tested cutting tools samples increases according to a fractal dimension increase of their wear surface.

  18. Improved wear resistance of functional diamond like carbon coated Ti-6Al-4V alloys in an edge loading conditions.

    PubMed

    Choudhury, Dipankar; Lackner, Jürgen M; Major, Lukasz; Morita, Takehiro; Sawae, Yoshinori; Bin Mamat, Azuddin; Stavness, Ian; Roy, Chanchal K; Krupka, Ivan

    2016-06-01

    This study investigates the durability of functional diamond-like carbon (DLC) coated titanium alloy (Ti-6Al-4V) under edge loading conditions for application in artificial hip joints. The multilayered (ML) functional DLC coatings consist of three key layers, each of these layers were designed for specific functions such as increasing fracture strength, adapting stress generation and enhancing wear resistance. A 'ball-on-disk' multi-directional wear tester was used in the durability test. Prior to the wear testing, surface hardness, modulus elasticity and Raman intensity were measured. The results revealed a significant wear reduction to the DLC coated Ti-6Al-4V disks compared to that of non-coated Ti-6Al-4V disks. Remarkably, the counterpart Silicon Nitride (Si3N4) balls also yielded lowered specific wear rate while rubbed against the coated disks. Hence, the pairing of a functional multilayered DLC and Si3N4 could be a potential candidate to orthopedics implants, which would perform a longer life-cycle against wear caused by edge loading. PMID:27085502

  19. Investigation on the Surface Integrity and Tool Wear in Cryogenic Machining

    SciTech Connect

    Dutra Xavier, Sandro E.; Delijaicov, Sergio; Farias, Adalto de; Stipkovic Filho, Marco; Ferreira Batalha, Gilmar

    2011-01-17

    This work aimed to study the influences of cryogenic cooling on tool wear, comparing it to dry machining during on the surface integrity of test circular steel SAE 52100 hardened to 62 HRC, during the turning of the face, with the use of special PcBN, using liquid nitrogen with cooler. The surface integrity parameters analyzed were: surface roughness and white layer and tool wear. The results of the present work indicated reduction in tool wear, which enhance the tool life.

  20. Abrasive Wear Resistance of Tool Steels Evaluated by the Pin-on-Disc Testing

    NASA Astrophysics Data System (ADS)

    Bressan, José Divo; Schopf, Roberto Alexandre

    2011-05-01

    Present work examines tool steels abrasion wear resistance and the abrasion mechanisms which are one main contributor to failure of tooling in metal forming industry. Tooling used in cutting and metal forming processes without lubrication fails due to this type of wear. In the workshop and engineering practice, it is common to relate wear resistance as function of material hardness only. However, there are others parameters which influences wear such as: fracture toughness, type of crystalline structure and the occurrence of hard precipitate in the metallic matrix and also its nature. In the present investigation, the wear mechanisms acting in tool steels were analyzed and, by normalized tests, wear resistance performance of nine different types of tool steels were evaluated by pin-on-disc testing. Conventional tool steels commonly used in tooling such as AISI H13 and AISI A2 were compared in relation to tool steels fabricated by sintering process such as Crucible CPM 3V, CPM 9V and M4 steels. Friction and wear testing were carried out in a pin-on-disc automated equipment which pin was tool steel and the counter-face was a abrasive disc of silicon carbide. Normal load of 5 N, sliding velocity of 0.45 m/s, total sliding distance of 3000 m and room temperature were employed. The wear rate was calculated by the Archard's equation and from the plotted graphs of pin cumulated volume loss versus sliding distance. Specimens were appropriately heat treated by quenching and three tempering cycles. Percentage of alloying elements, metallographic analyses of microstructure and Vickers microhardness of specimens were performed, analyzed and correlated with wear rate. The work is concluded by the presentation of a rank of tool steel wear rate, comparing the different tool steel abrasion wear resistance: the best tool steel wear resistance evaluated was the Crucible CPM 9V steel.

  1. Experimental results and wear predictions of petal tools that freely rotate.

    PubMed

    Cordero-Dávila, Alberto; Cabrera-Peláez, Víctor; Cuautle-Cortés, Jorge; González-García, Jorge; Robledo-Sánchez, Carlos; Bautista-Elivar, Nazario

    2005-03-10

    It is difficult to calculate the wear produced by free-pinned tools because their angular movement is not entirely predictable. We analyze the wear produced with free-pinned ring tools, using both simulations and experiments. We conclude that the wear of an incomplete ring is directly proportional to the ring's angular size, independently of the mean radius of the ring. We present an algorithm for calculation of the wear produced by free-pinned petal tools, as they can be considered a linear combination of incomplete free-pinned ring tools. Finally, we apply this result to the enhancement of a defective flat surface and to making a concave spheric surface.

  2. Triphasic Tooling with Small Oriented Diamond Tip for Turning and Smoothing Lightweight Mirrors

    NASA Technical Reports Server (NTRS)

    Voronov, O. A.; Tompa, G. S.; Kear, B. H.; Veress, V.

    2004-01-01

    We are developing a new method for the growth of small diamond crystals at very high temperatures and pressures directly from a carbon melt. A prototype "Supercell" has been developed for this purpose. This system is capable of high rate crystal growth in relatively large working volumes. The resulting high quality diamond crystals will be incorporated into a triphasic diamond/titanium carbide/titanium composite tool, with an oriented diamond crystal at its tip. High pressure is needed to prevent degradation of diamond at high temperature, and to ensure the formation of a crack & composite structure. After grinding and polishing, the composite material will be joined to a steel holder, thus forming a diamond-tipped tool for turning and smoothing of a mirror surface. A properly oriented single-crystal diamond cuts and smoothes much better than a conventional polycrystalline diamond crystal. This is because the hardness depends on crystallographic orientation-the difference corresponds to 60-100 GPa on the Knoop scale. Our goal is to achieve surface roughness of about 1 nm, which will be accomplished by precision cutting and smoothing. The hardness of the functionally-graded diamond/titanium carbide/titanium composite tool varies from 100 GPa at its tip to 15 GPa at its base. Previous work has shown that the mass of machined material using an oriented-diamond tool is much larger than that for a standard diamond-metal composite tool.

  3. Advanced Prediction of Tool Wear by Taking the Load History into Consideration

    NASA Astrophysics Data System (ADS)

    Ersoy, K.; Nuernberg, G.; Herrmann, G.; Hoffmann, H.

    2007-04-01

    A disadvantage of the conventional methods of simulating the wear occurring in deep drawing processes is that the wear coefficient, and thus wear too, is considered to be constant along loading duration, which, in case of deep drawing, corresponds to sliding distance and number of punch strokes. However, in reality, it is a known fact that wear development is not constant over time. In former studies, the authors presented a method, which makes it possible to consider the number of punch strokes in the simulation of wear. Another enhancement of this method is introduced in this paper. It is proposed to consider wear as a function of wear work instead of the number of punch strokes. Using this approach, the wear coefficients are implemented as a function of wear work and fully take into account the load history of the respective node. This enhancement makes it possible to apply the variable wear coefficients to completely different geometries, where one punch stroke involves different sliding distance or pressure values than the experiments with which the wear coefficients were determined. In this study, deep drawing experiments with a cylindrical cup geometry were carried out, in which the characteristic wear coefficient values as well as their gradients along the life cycle were determined. In this case, the die was produced via rapid tooling techniques. The prediction of tool wear is carried out with REDSY, a wear simulation software which was developed at the Institute of Metal Forming and Casting, TU-Muenchen. The wear predictions made by this software are based on the results of a conventional deep drawing simulation. For the wear modelling a modified Archard model was used.

  4. Wear resistance of thick diamond like carbon coatings against polymeric materials used in single screw plasticizing technology

    NASA Astrophysics Data System (ADS)

    Zitzenbacher, G.; Liu, K.; Forsich, C.; Heim, D.

    2015-05-01

    Wear on the screw and barrel surface accompany polymer single screw plasticizing technology from the beginning. In general, wear on screws can be reduced by using nitrided steel surfaces, fused armour alloys on the screw flights and coatings. However, DLC-coatings (Diamond Like Carbon) comprise a number of interesting properties such as a high hardness, a low coefficient of friction and an excellent corrosion resistance due to their amorphous structure. The wear resistance of about 50 µm thick DLC-coatings against polyamide 6.6, polybutylene terephthalate and polypropylene is investigated in this paper. The tribology in the solids conveying zone of a single screw extruder until the beginning of melting is evaluated using a pin on disc tribometer and a so called screw tribometer. The polymeric pins are pressed against coated metal samples using the pin on disc tribometer and the tests are carried out at a defined normal force and sliding velocity. The screw tribometer is used to perform tribological experiments between polymer pellets and rotating coated metal shafts simulating the extruder screw. Long term experiments were performed to evaluate the wear resistance of the DLC-coating. A reduction of the coefficient of friction can be observed after a frictional distance of about 20 kilometers using glass fibre reinforced polymeric materials. This reduction is independent on the polymer and accompanied by a black layer on the wear surface of the polymeric pins. The DLC-coated metal samples show an up to 16 µm deep wear track after the 100 kilometer test period against the glass fiber filled materials only.

  5. Study on the wear mechanism and tool life of coated gun drill

    NASA Astrophysics Data System (ADS)

    Wang, Yongguo; Yan, Xiangping; Chen, Xiaoguang; Sun, Changyu; Zhang, Xi

    2010-12-01

    A comprehensive investigation of the wear progress for solid carbide gun drill coated with TiAlN by machining steel S48CSiV at a cutting speed of 12.66m/s has been performed. Cutting torque was recorded and tool wear mechanism was studied. The surface morphology of the tool and the chip have been studied by using scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Results show that cutting torque fluctuates between 3% and 5% when machining less than 130 pieces of crankshaft, but it will sharply increased to nearly 18% while machining 150 pieces of crankshaft because the coating is damaged and the wear becoming severity. The dominant wear mechanisms are adhesive wear and chemical dissolution wear.

  6. Study on the wear mechanism and tool life of coated gun drill

    NASA Astrophysics Data System (ADS)

    Wang, Yongguo; Yan, Xiangping; Chen, Xiaoguang; Sun, Changyu; Zhang, Xi

    2011-05-01

    A comprehensive investigation of the wear progress for solid carbide gun drill coated with TiAlN by machining steel S48CSiV at a cutting speed of 12.66m/s has been performed. Cutting torque was recorded and tool wear mechanism was studied. The surface morphology of the tool and the chip have been studied by using scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Results show that cutting torque fluctuates between 3% and 5% when machining less than 130 pieces of crankshaft, but it will sharply increased to nearly 18% while machining 150 pieces of crankshaft because the coating is damaged and the wear becoming severity. The dominant wear mechanisms are adhesive wear and chemical dissolution wear.

  7. Method of forming fluorine-bearing diamond layer on substrates, including tool substrates

    DOEpatents

    Chang, R. P. H.; Grannen, Kevin J.

    2002-01-01

    A method of forming a fluorine-bearing diamond layer on non-diamond substrates, especially on tool substrates comprising a metal matrix and hard particles, such as tungsten carbide particles, in the metal matrix. The substrate and a fluorine-bearing plasma or other gas are then contacted under temperature and pressure conditions effective to nucleate fluorine-bearing diamond on the substrate. A tool insert substrate is treated prior to the diamond nucleation and growth operation by etching both the metal matrix and the hard particles using suitable etchants.

  8. A review of the use of wear-resistant coatings in the cutting-tool industry

    NASA Technical Reports Server (NTRS)

    Salik, J.

    1983-01-01

    The main mechanisms involved in the wear of cutting tools are reviewed. Evaluation of the different coating properties required for the reduction of the different kinds of wear was also reviewed. The types of coatings and their ranges of applicability are presented and discussed in view of their properties. Various coating processes as well as their advantages and shortcomings are described. Potential future developments in the field of wear-resistant coatings are discussed.

  9. Trace element compositions of submicroscopic inclusions in coated diamond: A tool for understanding diamond petrogenesis

    NASA Astrophysics Data System (ADS)

    Tomlinson, Emma; De Schrijver, Isabel; De Corte, Katrien; Jones, Adrian P.; Moens, Luc; Vanhaecke, Frank

    2005-10-01

    Trace element compositions of submicroscopic inclusions in both the core and the coat of five coated diamonds from the Democratic Republic of Congo (DRC, formerly Zaire) have been analyzed by Laser Ablation Inductively Coupled Mass Plasma Spectrometry (LA-ICP-MS). Both the diamond core and coat inclusions show a general 2-4-fold enrichment in incompatible elements relative to major elements. This level of enrichment is unlikely to be explained by the entrapment of silicate mantle minerals (olivine, garnet, clinopyroxene, phlogopite) alone and thus submicroscopic fluid or glass inclusions are inferred in both the diamond coat and in the gem quality diamond core. The diamond core fluids have elevated High Field Strength Element (Ti, Ta, Zr, Nb) concentrations and are enriched in U relative to inclusions in the diamond coats and relative to chondrite. The core fluids are also moderately enriched in LILE (Ba, Sr, K). Therefore, we suggest that the diamond cores contain inclusions of silicate melt. However, the Ni content and Ni/Fe ratio of the trapped fluid are very high for a silicate melt in equilibrium with mantle minerals; high Ni and Co concentrations in the diamond cores are attributed to the presence of a sulfide phase coexisting with silicate melt in the diamond core inclusions. Inclusions in the diamond coat are enriched in LILE (U, Ba, Sr, K) and La over the diamond core fluids and to chondrite. The coats have incompatible element ratios similar to natural carbonatite (coat fluid: Na/Ba ≈0.66, La/Ta≈130). The coat fluid is also moderately enriched in HFSE (Ta, Nb, Zr) when normalized to chondritic Al. LILE and La enrichment is related to the presence of a carbonatitic fluid in the diamond coat inclusions, which is mixed with a HFSE-rich hydrous silicate fluid similar to that in the core. The composition of the coat fluid is consistent with a genetic link to group 1 kimberlite.

  10. Impact of tool wear on joint strength in friction stir spot welding of DP 980 steel

    SciTech Connect

    Miles, Michael; Ridges, Chris; Hovanski, Yuri; Peterson, Jeremy; Santella, M. L.; Steel, Russel

    2011-09-14

    Friction stir spot welding has been shown to be a viable method of joining ultra high strength steel (UHSS), both in terms of joint strength and process cycle time. However, the cost of tooling must be reasonable in order for this method to be adopted as an industrial process. Recently a new tool alloy has been developed, using a blend of PCBN and tungsten rhenium (W-Re) in order to improve the toughness of the tool. Wear testing results are presented for two of these alloys: one with a composition of 60% PCBN and 40% W-Re, and one with 70% PCBN and 30% W-Re. The sheet material used for all wear testing was 1.4 mm DP 980. Lap shear testing was used to show the relationship between tool wear and joint strength. The Q70 tool provided the best combination of wear resistance and joint strength.

  11. Diamond cutting tools with a Ni3Al matrix processed by reaction pseudo-hipping

    NASA Astrophysics Data System (ADS)

    Hwang, K. S.; Yang, T. H.; Hu, S. C.

    2005-10-01

    Nickel aluminide, Ni3Al, has high hot strength, which could help overcome the high heat and the interrupted vibrations that diamond cutting tools encounter during operation. Reaction pseudo-hipping, on the other hand, require only a short dwell time at high temperatures, which are detrimental to the diamond grits. Thus, it is promising to combine the unique nickel aluminide with the unique reaction pseudo-hipping process and replace the commonly used cobalt matrix. This study reports for the first time the process and application of reaction-pseudo-hipped Ni3Al matrix for diamond tools. In this work, mixtures of elemental nickel, aluminum, boron powder, and diamond particles are reaction-pseudo-hipped. Densities greater than 99 pct and mechanical properties comparable to those of the cobalt are attained. With high-grade diamond grits, the tools thus prepared show, under dry cutting conditions, a grinding ratio 118 pct higher than that with the cobalt matrix.

  12. Surface characterization of diamond film tool grinding on the monocrystal sapphire under different liquid environments

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Lu, Wenzhuang; Zhou, Hai; Yang, Bin; Zuo, Dunwen

    2016-11-01

    Surface characterization of diamond film tool on the monocrystal sapphire under H2O, 3% ethylene glycol and 3% ethylenediamine was investigated. The typical components and chemical changes of the surface of diamond thick film were studied by means of Raman and XPS. Results showed that tribological properties of diamond film tool were associated with the liquid environment located the grinding. Diamond film tool under 3% ethylenediamine solution exhibited the minimum value of friction coefficient, while that under H2O exhibited maximum value of friction coefficient. As the ethylenediamine and ethylene glycol were added during the grinding process, the reaction between diamond film and the sapphire pieces occurred, and the chemical composition change of the surface was also studied. Under the same process parameters, a better surface quality of sapphire under the grinding fluid of ethylenediamine can be obtained.

  13. Study on the anti-wear performance of Ni-base composite coating sucker joint that contains nano-diamond and nano-polytetrafluoroethylene.

    PubMed

    Wang, Wei-Zhang; Yan, Xiang-Zhen; Wang, Hai-Wen; Wang, Ming-Bo

    2009-02-01

    With the development of oilfields, the problem of eccentric wear between casing and sucker rod in rod-pumped wells operation is more and more severe. Investigations on the eccentric wear show that the abrasion of sucker rod joint is more serious than the sucker rod itself. A new method of producing the Ni-base composite coating that contains nano-diamond and nano-polytetrafluoroethylene (PTFE) on sucker joint obtained by electrodeposition is presented in this paper. The test results show that the anti-wear performance and hardness of the sucker rod improve significantly with the increase of nano-diamond. The addition of nano-PTFE particle is useful in reducing the friction factor. Field tests demonstrate that the life of the sucker rod joint is increased and the maintenance cycle of the rod-pumped well is prolonged. PMID:19441509

  14. Study on the anti-wear performance of Ni-base composite coating sucker joint that contains nano-diamond and nano-polytetrafluoroethylene.

    PubMed

    Wang, Wei-Zhang; Yan, Xiang-Zhen; Wang, Hai-Wen; Wang, Ming-Bo

    2009-02-01

    With the development of oilfields, the problem of eccentric wear between casing and sucker rod in rod-pumped wells operation is more and more severe. Investigations on the eccentric wear show that the abrasion of sucker rod joint is more serious than the sucker rod itself. A new method of producing the Ni-base composite coating that contains nano-diamond and nano-polytetrafluoroethylene (PTFE) on sucker joint obtained by electrodeposition is presented in this paper. The test results show that the anti-wear performance and hardness of the sucker rod improve significantly with the increase of nano-diamond. The addition of nano-PTFE particle is useful in reducing the friction factor. Field tests demonstrate that the life of the sucker rod joint is increased and the maintenance cycle of the rod-pumped well is prolonged.

  15. Analytical and Empirical Modeling of Wear and Forces of CBN Tool in Hard Turning - A Review

    NASA Astrophysics Data System (ADS)

    Patel, Vallabh Dahyabhai; Gandhi, Anishkumar Hasmukhlal

    2016-06-01

    Machining of steel material having hardness above 45 HRC (Hardness-Rockwell C) is referred as a hard turning. There are numerous models which should be scrutinized and implemented to gain optimum performance of hard turning. Various models in hard turning by cubic boron nitride tool have been reviewed, in attempt to utilize appropriate empirical and analytical models. Validation of steady state flank and crater wear model, Usui's wear model, forces due to oblique cutting theory, extended Lee and Shaffer's force model, chip formation and progressive flank wear have been depicted in this review paper. Effort has been made to understand the relationship between tool wear and tool force based on the different cutting conditions and tool geometries so that appropriate model can be used according to user requirement in hard turning.

  16. Methodology of evaluation of abrasive tool wear with the use of laser scanning microscopy.

    PubMed

    Lipiński, Dariusz; Kacalak, Wojciech; Tomkowski, Robert

    2014-01-01

    Grinding is one of the basic precise material removal methods. Abrasive and shape wear, as well as smearing of the tools' active surface handicap the processing results. The loss of cutting capacity in abrasive tools or alteration of their shape influences the surface quality and precision of the workpiece dimensions and its shape. Evaluation of the abrasive tool surface is the basic criterion of forecasting the tools' durability and the process results. The applied method of laser scanning made determination of the surface coordinates and subsequently of its geometric features with micrometric accuracy possible. Using the information on the abrasive tool surface geometric structure, a methodology of evaluation of the level of changes in geometric features of the tool during the grinding process was developed. Criteria for evaluation of the level of abrasive grains attritious wear, the degree of smearing of the abrasive tool surface and evaluation of the cutting capability of the abrasive tools were determined. The developed method allowed for evaluation of the level of abrasive tools' wear, and subsequently formed foundations for assessment of the influence of the grinding parameters on the durability of abrasive tools, evaluation of the influence of the parameters of the process of shaping the abrasive tools' active surfaces on their geometric characteristics and evaluation of the level of correlation between the monitored process parameters and the degree of the abrasive tools' wear.

  17. Investigation of machining damage and tool wear resulting from drilling powder metal aluminum alloy

    SciTech Connect

    Fell, H.A.

    1997-05-01

    This report documents the cutting of aluminum powder metallurgy (PM) parts for the North Carolina Manufacturing Extension Partnership. The parts, an aluminum powder metal formulation, were supplied by Sinter Metals Inc., of Conover, North Carolina. The intended use of the alloy is for automotive components. Machining tests were conducted at Y-12 in the machine shop of the Skills Demonstration Center in Building 9737. Testing was done on June 2 and June 3, 1997. The powder metal alloy tested is very abrasive and tends to wear craters and produce erosion effects on the chip washed face of the drills used. It also resulted in huge amounts of flank wear and degraded performance on the part of most drills. Anti-wear coatings on drills seemed to have an effect. Drills with the coating showed less wear for the same amount of cutting. The usefulness of coolants and lubricants in reducing tool wear and chipping/breakout was not investigated.

  18. Examining the Effect of the Die Angle on Tool Load and Wear in the Extrusion Process

    NASA Astrophysics Data System (ADS)

    Nowotyńska, Irena; Kut, Stanisław

    2014-04-01

    The tool durability is a crucial factor in each manufacturing process, and this also includes the extrusion process. Striving to achieve the higher product quality should be accompanied by a long-term tool life and production cost reduction. This article presents the comparative research of load and wear of die at various angles of working cone during the concurrent extrusion. The numerical calculations of a tool load during the concurrent extrusion were performed using the MSC MARC software using the finite element method (FEM). Archard model was used to determine and compare die wear. This model was implemented in the software using the FEM. The examined tool deformations and stress distribution were determined based on the performed analyses. The die wear depth at various working cone angles was determined. Properly shaped die has an effect on the extruded material properties, but also controls loads, elastic deformation, and the tool life.

  19. Correction method for the error of diamond tool's radius in ultra-precision cutting

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Yu, Jing-chi

    2010-10-01

    The compensation method for the error of diamond tool's cutting edge is a bottle-neck technology to hinder the high accuracy aspheric surface's directly formation after single diamond turning. Traditional compensation was done according to the measurement result from profile meter, which took long measurement time and caused low processing efficiency. A new compensation method was firstly put forward in the article, in which the correction of the error of diamond tool's cutting edge was done according to measurement result from digital interferometer. First, detailed theoretical calculation related with compensation method was deduced. Then, the effect after compensation was simulated by computer. Finally, φ50 mm work piece finished its diamond turning and new correction turning under Nanotech 250. Testing surface achieved high shape accuracy pv 0.137λ and rms=0.011λ, which approved the new compensation method agreed with predictive analysis, high accuracy and fast speed of error convergence.

  20. Use-Wear Patterns on Wild Macaque Stone Tools Reveal Their Behavioural History

    PubMed Central

    Haslam, Michael; Gumert, Michael D.; Biro, Dora; Carvalho, Susana; Malaivijitnond, Suchinda

    2013-01-01

    Burmese long-tailed macaques (Macaca fascicularis aurea) are one of a limited number of wild animal species to use stone tools, with their tool use focused on pounding shelled marine invertebrates foraged from intertidal habitats. These monkeys exhibit two main styles of tool use: axe hammering of oysters, and pound hammering of unattached encased foods. In this study, we examined macroscopic use-wear patterns on a sample of 60 wild macaque stone tools from Piak Nam Yai Island, Thailand, that had been collected following behavioural observation, in order to (i) quantify the wear patterns in terms of the types and distribution of use-damage on the stones, and (ii) develop a Use-Action Index (UAI) to differentiate axe hammers from pound hammers by wear patterns alone. We used the intensity of crushing damage on differing surface zones of the stones, as well as stone weight, to produce a UAI that had 92% concordance when compared to how the stones had been used by macaques, as observed independently prior to collection. Our study is the first to demonstrate that quantitative archaeological use-wear techniques can accurately reconstruct the behavioural histories of non-human primate stone tools. PMID:23977365

  1. Modelling of tunnelling processes and rock cutting tool wear with the particle finite element method

    NASA Astrophysics Data System (ADS)

    Carbonell, Josep Maria; Oñate, Eugenio; Suárez, Benjamín

    2013-09-01

    Underground construction involves all sort of challenges in analysis, design, project and execution phases. The dimension of tunnels and their structural requirements are growing, and so safety and security demands do. New engineering tools are needed to perform a safer planning and design. This work presents the advances in the particle finite element method (PFEM) for the modelling and the analysis of tunneling processes including the wear of the cutting tools. The PFEM has its foundation on the Lagrangian description of the motion of a continuum built from a set of particles with known physical properties. The method uses a remeshing process combined with the alpha-shape technique to detect the contacting surfaces and a finite element method for the mechanical computations. A contact procedure has been developed for the PFEM which is combined with a constitutive model for predicting the excavation front and the wear of cutting tools. The material parameters govern the coupling of frictional contact and wear between the interacting domains at the excavation front. The PFEM allows predicting several parameters which are relevant for estimating the performance of a tunnelling boring machine such as wear in the cutting tools, the pressure distribution on the face of the boring machine and the vibrations produced in the machinery and the adjacent soil/rock. The final aim is to help in the design of the excavating tools and in the planning of the tunnelling operations. The applications presented show that the PFEM is a promising technique for the analysis of tunnelling problems.

  2. Effects of cutting parameters on tool insert wear in end milling of titanium alloy Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Luo, Ming; Wang, Jing; Wu, Baohai; Zhang, Dinghua

    2016-06-01

    Titanium alloy is a kind of typical hard-to-cut material due to its low thermal conductivity and high strength at elevated temperatures, this contributes to the fast tool wear in the milling of titanium alloys. The influence of cutting conditions on tool wear has been focused on the turning process, and their influence on tool wear in milling process as well as the influence of tool wear on cutting force coefficients has not been investigated comprehensively. To fully understand the tool wear behavior in milling process with inserts, the influence of cutting parameters on tool wear in the milling of titanium alloys Ti6Al4V by using indexable cutters is investigated. The tool wear rate and trends under different feed per tooth, cutting speed, axial depth of cut and radial depth of cut are analyzed. The results show that the feed rate per tooth and the radial depth of cut have a large influence on tool wear in milling Ti6Al4V with coated insert. To reduce tool wear, cutting parameters for coated inserts under experimental cutting conditions are set as: feed rate per tooth less than 0.07 mm, radial depth of cut less than 1.0 mm, and cutting speed sets between 60 and 150 m/min. Investigation on the relationship between tool wear and cutting force coefficients shows that tangential edge constant increases with tool wear and cutter edge chipping can lead to a great variety of tangential cutting force coefficient. The proposed research provides the basic data for evaluating the machinability of milling Ti6Al4V alloy with coated inserts, and the recommend cutting parameters can be immediately applied in practical production.

  3. Feasibility of using acoustic emission to determine in-process tool wear

    SciTech Connect

    Lazarus, L.J.

    1996-04-01

    Acoustic emission (AE) was evaluated for its ability to predict and recognize failure of cutting tools during machining processes when the cutting tool rotates and the workpiece is stationary. AE output was evaluated with a simple algorithm. AE was able to detect drill failure when the transducer was mounted on the workpiece holding fixture. Drill failure was recognized as size was reduced to 0.0003 in. diameter. The ability to predict failure was reduced with drill size, drill material elasticity, and tool coating. AE output for the turning process on a lathe was compared to turning tool insert wear. The turning tool must have sufficient wear to produce a detectable change in AE output to predict insert failure.

  4. Fast 3D reconstruction of tool wear based on monocular vision and multi-color structured light illuminator

    NASA Astrophysics Data System (ADS)

    Wang, Zhongren; Li, Bo; Zhou, Yuebin

    2014-11-01

    Fast 3D reconstruction of tool wear from 2D images has great importance to 3D measuring and objective evaluating tool wear condition, determining accurate tool change and insuring machined part's quality. Extracting 3D information of tool wear zone based on monocular multi-color structured light can realize fast recovery of surface topography of tool wear, which overcomes the problems of traditional methods such as solution diversity and slow convergence when using SFS method and stereo match when using 3D reconstruction from multiple images. In this paper, a kind of new multi-color structured light illuminator was put forward. An information mapping model was established among illuminator's structure parameters, surface morphology and color images. The mathematical model to reconstruct 3D morphology based on monocular multi-color structured light was presented. Experimental results show that this method is effective and efficient to reconstruct the surface morphology of tool wear zone.

  5. Cyclostationarity approach for monitoring chatter and tool wear in high speed milling

    NASA Astrophysics Data System (ADS)

    Lamraoui, M.; Thomas, M.; El Badaoui, M.

    2014-02-01

    Detection of chatter and tool wear is crucial in the machining process and their monitoring is a key issue, for: (1) insuring better surface quality, (2) increasing productivity and (3) protecting both machines and safe workpiece. This paper presents an investigation of chatter and tool wear using the cyclostationary method to process the vibrations signals acquired from high speed milling. Experimental cutting tests were achieved on slot milling operation of aluminum alloy. The experimental set-up is designed for acquisition of accelerometer signals and encoding information picked up from an encoder. The encoder signal is used for re-sampling accelerometers signals in angular domain using a specific algorithm that was developed in LASPI laboratory. The use of cyclostationary on accelerometer signals has been applied for monitoring chatter and tool wear in high speed milling. The cyclostationarity appears on average properties (first order) of signals, on the energetic properties (second order) and it generates spectral lines at cyclic frequencies in spectral correlation. Angular power and kurtosis are used to analyze chatter phenomena. The formation of chatter is characterized by unstable, chaotic motion of the tool and strong anomalous fluctuations of cutting forces. Results show that stable machining generates only very few cyclostationary components of second order while chatter is strongly correlated to cyclostationary components of second order. By machining in the unstable region, chatter results in flat angular kurtosis and flat angular power, such as a pseudo (white) random signal with flat spectrum. Results reveal that spectral correlation and Wigner Ville spectrum or integrated Wigner Ville issued from second-order cyclostationary are an efficient parameter for the early diagnosis of faults in high speed machining, such as chatter, tool wear and bearings, compared to traditional stationary methods. Wigner Ville representation of the residual signal shows

  6. Diamond anvil cells: a new tool for high pressure studies

    SciTech Connect

    Taylor, R.D.

    1985-01-01

    Literally hundreds of papers have appeared in the last few years covering a myriad of uses of the diamond anvil cells. The crescendo shows no signs of abating. Static pressures as high as 1.8 megabar have been reported. Still higher pressures appear possible. Measurements have been made at dilution refrigerator temperatures (less than 50 millikelvins) and to temperatures over 1000 C in special sample ovens. Obviously these methods cannot be applied to every physics problem, but the limitations of the DAC are being challenged daily.

  7. On the Problem of Wear Resistant Coatings Separation From Tools and Machine Elements

    NASA Astrophysics Data System (ADS)

    Petrushin, S. I.; Gubaidulina, R. H.; Gruby, S. V.; Likholat, A. V.

    2015-09-01

    The article considers separation of wear resistant coatings of tool and engineering materials which arises both during coating fabrication and use of the product. The cause of this phenomenon is assumed to be related to thermal residual stresses generating on the coating- substrate border. These stresses have been analyzed and methods are provided to calculate it after produced composite material is cooled down from the temperature of coating synthesis to the ambient temperature. A no-fracture condition has been stated in relation to coating- substrate thicknesses, temperature differences and physical and mechanical properties of combined materials. The issue of intermediate layer incorporation with pre-set parameters has been discussed. A co-effect of thermal residual and functional stresses on the strength of the boundary layer has been considered when heating, tension and compression of a product with wear resistant coating. Conclusions have been made, as well as recommendations to improve fracture strength of products with thin wear resistant coatings.

  8. A comparative assessment of texture analysis techniques applied to bone tool use-wear

    NASA Astrophysics Data System (ADS)

    Watson, Adam S.; Gleason, Matthew A.

    2016-06-01

    The study of bone tools, a specific class of artifacts often essential to perishable craft production, provides insight into industries otherwise largely invisible archaeologically. Building on recent breakthroughs in the analysis of microwear, this research applies confocal laser scanning microscopy and texture analysis techniques drawn from the field of surface metrology to identify use-wear patterns on experimental and archaeological bone artifacts. Our approach utilizes both conventional parameters and multi-scale geometric characterizations of the areas of worn surfaces to identify statistical similarities as a function of scale. The introduction of this quantitative approach to the study of microtopography holds significant potential for advancement in use-wear studies by reducing inter-observer variability and identifying new parameters useful in the detection of differential wear-patterns.

  9. Design and fabrication of nano-scale single crystal diamond cutting tool by focused ion beam (FIB) milling

    NASA Astrophysics Data System (ADS)

    Baek, Seung-Yub

    2015-07-01

    Micro/nanoscale diamond cutting tools used in ultra-precision machining can be fabricated by precision grinding, but it is hard to fabricate a tool with a nanometric cutting edge and complex configurations. High-precision geometry accuracy and special shapes for microcutting tools with sharp edges can be achieved by FIB milling. Because the FIB milling method induces much smaller machining stress compared with conventional precision grinding methods. In this study, the FIB milling characteristics of single-crystal diamond were investigated, along with methods for decreasing the FIB-induced damage on diamond tools. Lift-off process method and Pt(Platinum) coating process method with FIB milling were investigated to reduce the damage layer on diamond substrate and quadrilateral-shaped single-crystal diamond cutting tool with cutting edge width under 500 nm were obtained.

  10. Characterization of coating wear phenomena in nitride and carbide coated tool inserts

    SciTech Connect

    Fenske, G.R.; Kaufherr, N.; Lee, R.H.; Kramer, B.M.; Bunshah, R.F.; Sproul, W.D.

    1988-01-01

    Hard nitride- and carbide- coatings of Ti, Zr, and Hf were deposited on T-15 cutting tool inserts using high-rate reactive sputtering (HRRS) and activated reactive evaporation (ARE) processes. The coated inserts were subjected to a series of metal cutting tests to evaluate their performance and to compare their relative ranking with wear model predictions. The cutting tests indicated the coated inserts outperformed uncoated inserts by a factor of 2- to 10 depending on the coating process and composition; however their ranking based on measured lifetime (to reach a 0.003 in. crater depth) did not agree with predicted wear model predictions. Subsequently, a series of short-term cutting tests were initiated to study the wear behavior of the coatings during the early stages of the wear process when the coating was still intact. Post-test examination of the inserts suggest that the predominant wear mechanism was not due to abrasion or thermochemical dissolution as predicted by the model, but was a result of substrate softening followed by microfracture of the coating. The substrate softening is attributed to the severe cutting conditions (325 sfpm under dry cutting conditions) used in the cutting tests. 12 refs., 5 figs., 1 tab.

  11. Surface Roughness and Tool Wear on Cryogenic Treated CBN Insert on Titanium and Inconel 718 Alloy Steel

    NASA Astrophysics Data System (ADS)

    Thamizhmanii, S.; Mohideen, R.; Zaidi, A. M. A.; Hasan, S.

    2015-12-01

    Machining of materials by super hard tools like cubic boron nitride (cbn) and poly cubic boron nitride (pcbn) is to reduce tool wear to obtain dimensional accuracy, smooth surface and more number of parts per cutting edge. wear of tools is inevitable due to rubbing action between work material and tool edge. however, the tool wear can be minimized by using super hard tools by enhancing the strength of the cutting inserts. one such process is cryogenic process. this process is used in all materials and cutting inserts which requires wear resistance. the cryogenic process is executed under subzero temperature -186° celsius for longer period of time in a closed chamber which contains liquid nitrogen. in this research, cbn inserts with cryogenically treated was used to turn difficult to cut metals like titanium, inconel 718 etc. the turning parameters used is different cutting speeds, feed rates and depth of cut. in this research, titanium and inconel 718 material were used. the results obtained are surface roughness, flank wear and crater wear. the surface roughness obtained on titanium was lower at high cutting speed compared with inconel 718. the flank wear was low while turning titanium than inconel 718. crater wear is less on inconel 718 than titanium alloy. all the two materials produced saw tooth chips.

  12. Analyzing the performance of diamond-coated micro end mills.

    SciTech Connect

    Torres, C. D.; Heaney, P. J.; Sumant, A. V.; Hamilton, M. A.; Carpick, R. W.; Pfefferkorn, F. E.; Univ. of Wisconsin at Madison; Univ. of Pennsylvania

    2009-06-01

    A method is presented to improve the tool life and cutting performance of 300 {micro}m diameter tungsten carbide (WC) micro end mills by applying thin (<300 nm) fine-grained diamond (FGD) and nanocrystalline diamond (NCD) coatings using the hot-filament chemical vapor deposition (HF-CVD) process. The performance of the diamond-coated tools has been evaluated by comparing their performance in dry slot milling of 6061-T6 aluminum against uncoated WC micro end mills. Tool wear, coating integrity, and chip morphology were characterized using SEM and white light interferometry. The initial test results show a dramatic improvement in the tool integrity (i.e., corners not breaking off), a lower wear rate, no observable adhesion of aluminum to the diamond-coated tool, and a significant reduction in the cutting forces (>50%). Reduction of the cutting forces is attributed to the low friction and adhesion of the diamond coating. However, approximately 80% of the tools coated with the larger FGD coatings failed during testing due to delamination. Additional machining benefits were attained for the NCD films, which was obtained by using a higher nucleation density seeding process for diamond growth. This process allowed for thinner, smaller grained diamond coatings to be deposited on the micro end mills, and enabled continued operation of the tool even after the integrity of the diamond coating had been compromised. As opposed to the FGD-coated end mills, only 40% of the NCD-tools experienced delamination issues.

  13. Surface Roughness Model Based on Force Sensors for the Prediction of the Tool Wear

    PubMed Central

    de Agustina, Beatriz; Rubio, Eva María; Sebastián, Miguel Ángel

    2014-01-01

    In this study, a methodology has been developed with the objective of evaluating the surface roughness obtained during turning processes by measuring the signals detected by a force sensor under the same cutting conditions. In this way, the surface quality achieved along the process is correlated to several parameters of the cutting forces (thrust forces, feed forces and cutting forces), so the effect that the tool wear causes on the surface roughness is evaluated. In a first step, the best cutting conditions (cutting parameters and radius of tool) for a certain quality surface requirement were found for pieces of UNS A97075. Next, with this selection a model of surface roughness based on the cutting forces was developed for different states of wear that simulate the behaviour of the tool throughout its life. The validation of this model reveals that it was effective for approximately 70% of the surface roughness values obtained. PMID:24714391

  14. Surface roughness model based on force sensors for the prediction of the tool wear.

    PubMed

    de Agustina, Beatriz; Rubio, Eva María; Sebastián, Miguel Ángel

    2014-04-04

    In this study, a methodology has been developed with the objective of evaluating the surface roughness obtained during turning processes by measuring the signals detected by a force sensor under the same cutting conditions. In this way, the surface quality achieved along the process is correlated to several parameters of the cutting forces (thrust forces, feed forces and cutting forces), so the effect that the tool wear causes on the surface roughness is evaluated. In a first step, the best cutting conditions (cutting parameters and radius of tool) for a certain quality surface requirement were found for pieces of UNS A97075. Next, with this selection a model of surface roughness based on the cutting forces was developed for different states of wear that simulate the behaviour of the tool throughout its life. The validation of this model reveals that it was effective for approximately 70% of the surface roughness values obtained.

  15. Development of a method for predicting the performance and wear of PDC (polycrystalline diamond compact) drill bits

    SciTech Connect

    Glowka, D.A.

    1987-09-01

    A method is developed for predicting cutter forces, temperatures, and wear on PDC bits as well as integrated bit performance parameters such as weight-on-bit, drilling torque, and bit imbalance. A computer code called PDCWEAR has been developed to make this method available as a tool for general bit design and analysis. The method uses single-cutter data to provide a measure of rock drillability and employs theoretical considerations to account for interaction among closely spaced cutters on the bit. Experimental data are presented to establish the effects of cutter size and wearflat area on the forces that develop during rock cutting. Waterjet assistance is shown to significantly reduce cutting forces, thereby potentially extending bit life and reducing weight-on-bit and torque requirements in hard rock. The effects of several other design and operating parameters on bit life and drilling performance are also investigated.

  16. Diffusion-controlled wear of steel friction stir welding tools used on aluminum alloys

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Kalashnikova, T. A.; Kalashnikov, K. N.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.

    2015-10-01

    The worn surfaces of steel instruments used for friction stir welding on AMg5M aluminum alloy have been examined. An adhesion transfer layer resulted on the steel tool surface from welding the aluminum-magnesium alloy. Diffusion between this layer and steel base metal resulted in formation of an intermetallic Fe-Al layer (IMC). The hardness of the IMC has been measured using a nanohardness tester. It was found that the IMC layers maximum hardness changed from 998 to 1698 HV. The continuous IMC layers may serve as a wear-resistant coating, however, the IMC were also found in the shape of spikes directed into the tool's body, which created conditions for wear particle formation by fracture.

  17. Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

    DOEpatents

    Taylor, G.W.; Roybal, H.E.

    1983-11-14

    A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al/sub 2/O/sub 3/ yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

  18. Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

    DOEpatents

    Taylor, Gene W.; Roybal, Herman E.

    1985-01-01

    A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al.sub.2 O.sub.3 yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

  19. Process for ultra smooth diamond coating on metals and uses thereof

    NASA Technical Reports Server (NTRS)

    Vohra, Yogesh K. (Inventor); Catledge, Shane A. (Inventor)

    2001-01-01

    The present invention provides a new process to deposit well adhered ultra smooth diamond films on metals by adding nitrogen gas to the methane/hydrogen plasma created by a microwave discharge. Such diamond coating process is useful in tribological/wear resistant applications in bio-implants, machine tools, and magnetic recording industry.

  20. Effects of tool geometry and welding rates on the tool wear behavior and shape optimization in friction stir welding of aluminum alloy 6061 + 20% aluminum oxide MMC

    NASA Astrophysics Data System (ADS)

    Prado, Rafael Arcangel

    FSW is a new solid-state process currently being investigated for joining aluminum alloys that are difficult to weld, where there is no perceptible wear of the pin tool throughout the experiment. The present report investigates and examines tool wear in the friction-stir welding of Al 6061-T6 and Al 6061-T6 containing 20% (volume) Al2O3 particles, a metal matrix composite (MMC), in order to compare wear optimized tool geometries and corresponding parameters. The weld tool, referred to as pin tool or nib, did not exhibit any measurable wear in the FSW of the 6061 Al alloy even after traversing tens of meters of material. However, the pin tool geometry changed during the FSW of the Al 6061-T6 containing 20% (volume) Al2O3 particles. Tool wear was measured in relation to the original tool by weighing the photograph of the tool and comparing the percentage change relative to the original tool photograph. The maximum wear rate was roughly 0.64 %/cm at 1000 rpm for the MMC at 1 mm/s traverse speed. The best performance involving the least wear for MMC FSW was observed at a tool rotational speed of 500 rpm and a traverse speed of 3 mm/s; where the corresponding wear rate was 0.13 %/cm. Optical, scanning and transmission microscopy were used to characterize the microstructures of the base material and weld zone for the MMC confirming the solid phase nature of the technique. The microstructure of the friction stir weld zone shows a characteristic dynamic recrystallization phenomenon that acts as a mechanism to accommodate the super-plastic deformation and facilitates the bonding. Rockwell E hardness profiles for both aluminum alloys were measured from the base metals through the FSW zone near the through-thickness mid-section. In the FSW of Al 6061 containing 20% (volume) Al2O3 particles, tool wear has been shown to depend primarily on rotational and traverse speeds, with optimum wear occurring at 1000 rpm. However, as the traverse or actual weld speed is increased from 1

  1. Fabrication of continuous diffractive optical elements using a fast tool servo diamond turning process

    NASA Astrophysics Data System (ADS)

    Zhou, Jingbo; Li, Lei; Naples, Neil; Sun, Tao; Yi, Allen Y.

    2013-07-01

    Continuous diffractive optical elements (CDOEs) can be used for laser-beam reshaping, pattern generation and can help reduce large angle scattering. Lithography, the method for the production of binary diffractive surfaces, is not suitable for fabrication of CDOEs. Diamond turning using fast tool servo, on the other hand, is a non-cleanroom method for generating continuous microstructures with high precision and efficiency. In this paper, an algorithm for designing CDOEs is introduced. The moving least-squares (MLS) method is then used to obtain the local fitting equation of the diffractive surface. Based on the MLS fitting equation, the selection of diamond cutting tool geometries (including the tool nose radius, rake angle and clearance angle) is discussed and a tool nose radius compensation algorithm is included. This algorithm is a general method for the diamond turning of complex surfaces that can be represented by a point cloud. Surface measurements and diffractive patterns generated on test samples have shown that continuous diffractive surfaces were successfully machined. In the future, CDOEs can be machined on an optical mold surface for high-volume industrial production using methods such as injection molding.

  2. Microstructural analyses and wear behavior of the cemented carbide tools after laser surface treatment and PVD coating

    NASA Astrophysics Data System (ADS)

    Neves, Davi; Diniz, Anselmo Eduardo; Lima, Milton Sérgio Fernandes

    2013-10-01

    Adhesion is one of the most important characteristics of coating on cutting tools. Poor coating adhesion on the tool favors fragmentation and release of hard abrasive particles between the tool and the workpiece. These particles interact with the surfaces of the tool, accelerating its wear and decreasing tool life. One possible solution is the use of laser texturing prior to coating in order to achieve a desired surface topography with enhanced adhesion properties. In the texturing, a high-frequency short-pulse laser changes surface characteristics, generating resolidified material and selective vaporization. This work evaluated the effectiveness of laser texturing in improving the substrate-coating adhesion of PVD coated cemented carbide tools. To this end, the substrates were textured with a Nd:YAG laser, in four different intensities, and then coated with a PVD TiAlN film. To ascertain the effectiveness of laser texturing, Rockwell C indentation and turning experiments were performed on both textured tools and conventional unlasered tools. The PVD coated laser-textured tool showed better performance in the indentation and turning tests than the standard tools. A comparative evaluation of tool wear mechanisms indicated that texturing did not change the wear mechanisms, but altered their importance to tool wear. The anchoring provided by the higher roughness of the textured surface increased the adhesion of the coating on the substrate, thus increasing tool life. Additionally, the chemical modification of the carbide grains due to the laser heating might be responsible for an enhanced adhesion between coating and substrate.

  3. Tribology and Tool Wear of Hot Dip Galvanized Zinc Magnesium Alloys on Cold Rolled Steel Sheets

    NASA Astrophysics Data System (ADS)

    Raab, A. E.; Berger, E.; Freudenthaler, J.; Leomann, F.; Walch, C.

    2011-05-01

    Recently zinc based coatings on cold rolled steel with improved functionality in terms of forming and/or corrosion behaviour have been intensively investigated in the steel industry1,2,3. One of the most promising products are zinc magnesium alloys produced in hot dip galvanizing process. These coatings were already introduced in construction industry a few years ago1. With some modifications the improved properties of the coating are also interesting for automotive industry. In the present work the tribological potential of hot dip galvanized zinc magnesium coatings (HDG/ZM) produced at an industrial line under regular production, was studied in terms of sliding properties, adhesive and abrasive tool wear. First a short introduction into surface morphology of HDG/ZM will be given. For the tribological characterization of the material, which is the main topic of the contribution, different tests were performed on hot dip galvanised zinc magnesium material and results were compared with classic hot dip galvanized zinc coating (HDG/Z). The investigations are mainly based on the strip draw test which allows the determination of the friction coefficient directly by using a constant contact pressure. Deep drawing property was tested by forming model cups. The abrasive tool wear was tested using a standard test for material used in automotive industry. The adhesive tool wear was investigated by characterizing the coating material transferred to the tool in the strip draw test. All performed tests show an improved drawability of HDG/ZM compared to classical HDG/Z reference material. However the most promising difference between HDG/ZM and HDG/Z is that galling was found to be less for HDG/ZM than for HDG/Z. Therefore HDG/ZM is an interesting system not only with respect to corrosion protection but also in terms of tribology and provides clear advantages in formability.

  4. Tribology and Tool Wear of Hot Dip Galvanized Zinc Magnesium Alloys on Cold Rolled Steel Sheets

    SciTech Connect

    Raab, A. E.; Berger, E.; Freudenthaler, J.; Leomann, F.; Walch, C.

    2011-05-04

    Recently zinc based coatings on cold rolled steel with improved functionality in terms of forming and/or corrosion behaviour have been intensively investigated in the steel industry. One of the most promising products are zinc magnesium alloys produced in hot dip galvanizing process. These coatings were already introduced in construction industry a few years ago. With some modifications the improved properties of the coating are also interesting for automotive industry. In the present work the tribological potential of hot dip galvanized zinc magnesium coatings (HDG/ZM) produced at an industrial line under regular production, was studied in terms of sliding properties, adhesive and abrasive tool wear.First a short introduction into surface morphology of HDG/ZM will be given. For the tribological characterization of the material, which is the main topic of the contribution, different tests were performed on hot dip galvanised zinc magnesium material and results were compared with classic hot dip galvanized zinc coating (HDG/Z). The investigations are mainly based on the strip draw test which allows the determination of the friction coefficient directly by using a constant contact pressure. Deep drawing property was tested by forming model cups. The abrasive tool wear was tested using a standard test for material used in automotive industry. The adhesive tool wear was investigated by characterizing the coating material transferred to the tool in the strip draw test.All performed tests show an improved drawability of HDG/ZM compared to classical HDG/Z reference material. However the most promising difference between HDG/ZM and HDG/Z is that galling was found to be less for HDG/ZM than for HDG/Z. Therefore HDG/ZM is an interesting system not only with respect to corrosion protection but also in terms of tribology and provides clear advantages in formability.

  5. Advanced Diamond Anvil Techniques (Customized Diamond Anvils)

    SciTech Connect

    Weir, S

    2009-02-11

    A complete set of diamond-based fabrication tools now exists for making a wide range of different types of diamond anvils which are tailored for various high-P applications. Current tools include: CVD diamond deposition (making diamond); Diamond polishing, laser drilling, plasma etching (removal of diamond); and Lithography, 3D laser pantography (patterning features onto diamond); - Metal deposition (putting electrical circuits and metal masks onto diamond). Current applications include the following: Electrical Conductivity; Magnetic Susceptibility; and High-P/High-T. Future applications may include: NMR; Hall Effect; de Haas - Shubnikov (Fermi surface topology); Calorimetry; and thermal conductivity.

  6. On the possible role of triboplasma in friction and wear of diamond-like carbon films in hydrogen-containing environments.

    SciTech Connect

    Matta, C.; Eryilmaz, O.; Bouchet, M. I. D,; Erdemir, A.; Martin, J. M.; Nakayama, K.; Energy Systems; Lab. of Tribology and System Dynamics; Ciba Inst. of Tech.; National Inst. of Advanced Industrial Science and Technology

    2009-04-07

    Hydrogen-free diamond-like carbon (DLC) films (both amorphous (a-C) and tetrahedral amorphous carbon (ta-C)) suffer high friction and severe wear losses when tested in inert and/or high vacuum environments. However, they provide anomalous superlow friction and wear coefficients in the presence of hydrogen gas, water vapor and alcohol molecules in the test environment. In this paper, we used such films in a systematic study to further confirm that hydrogen indeed plays an important role in their friction and wear behaviors. To study the effect of hydrogen, we conducted sliding tests in a hydrogen-containing test chamber and analyzed the chemistry of their sliding contact surfaces using a time-of-flight secondary ion mass spectrometer. Clearly, the sliding contact regions of the carbon films became very rich in hydrogen after tribological tests in the hydrogen-containing chamber. In an attempt to understand the fundamental tribochemical mechanisms involved, we performed additional tests on these DLC films using a highly instrumented tribometer that permitted us the visualization of triboplasmas generating at or in the vicinity of the sliding surfaces. In this test system, we confirmed the formation of a triboplasma inside the contact area of the DLC films as evidenced by the characteristic UV radiation. Based on these observations, we believe that the formation of such triboplasmas within the contact zones of these DLC films may have triggered unique tribochemical reactions between hydrogen and carbon atoms on their sliding surfaces and thus resulted in very low friction and wear during tests in hydrogen-containing environments.

  7. Voltage assisted asymmetric nanoscale wear on ultra-smooth diamond like carbon thin films at high sliding speeds

    NASA Astrophysics Data System (ADS)

    Rajauria, Sukumar; Schreck, Erhard; Marchon, Bruno

    2016-05-01

    The understanding of tribo- and electro-chemical phenomenons on the molecular level at a sliding interface is a field of growing interest. Fundamental chemical and physical insights of sliding surfaces are crucial for understanding wear at an interface, particularly for nano or micro scale devices operating at high sliding speeds. A complete investigation of the electrochemical effects on high sliding speed interfaces requires a precise monitoring of both the associated wear and surface chemical reactions at the interface. Here, we demonstrate that head-disk interface inside a commercial magnetic storage hard disk drive provides a unique system for such studies. The results obtained shows that the voltage assisted electrochemical wear lead to asymmetric wear on either side of sliding interface.

  8. Voltage assisted asymmetric nanoscale wear on ultra-smooth diamond like carbon thin films at high sliding speeds

    PubMed Central

    Rajauria, Sukumar; Schreck, Erhard; Marchon, Bruno

    2016-01-01

    The understanding of tribo- and electro-chemical phenomenons on the molecular level at a sliding interface is a field of growing interest. Fundamental chemical and physical insights of sliding surfaces are crucial for understanding wear at an interface, particularly for nano or micro scale devices operating at high sliding speeds. A complete investigation of the electrochemical effects on high sliding speed interfaces requires a precise monitoring of both the associated wear and surface chemical reactions at the interface. Here, we demonstrate that head-disk interface inside a commercial magnetic storage hard disk drive provides a unique system for such studies. The results obtained shows that the voltage assisted electrochemical wear lead to asymmetric wear on either side of sliding interface. PMID:27150446

  9. Voltage assisted asymmetric nanoscale wear on ultra-smooth diamond like carbon thin films at high sliding speeds.

    PubMed

    Rajauria, Sukumar; Schreck, Erhard; Marchon, Bruno

    2016-01-01

    The understanding of tribo- and electro-chemical phenomenons on the molecular level at a sliding interface is a field of growing interest. Fundamental chemical and physical insights of sliding surfaces are crucial for understanding wear at an interface, particularly for nano or micro scale devices operating at high sliding speeds. A complete investigation of the electrochemical effects on high sliding speed interfaces requires a precise monitoring of both the associated wear and surface chemical reactions at the interface. Here, we demonstrate that head-disk interface inside a commercial magnetic storage hard disk drive provides a unique system for such studies. The results obtained shows that the voltage assisted electrochemical wear lead to asymmetric wear on either side of sliding interface. PMID:27150446

  10. Multiscale Multiphysics-Based Modeling and Analysis on the Tool Wear in Micro Drilling

    NASA Astrophysics Data System (ADS)

    Niu, Zhichao; Cheng, Kai

    2016-02-01

    In micro-cutting processes, process variables including cutting force, cutting temperature and drill-workpiece interfacing conditions (lubrication and interaction, etc.) significantly affect the tool wear in a dynamic interactive in-process manner. The resultant tool life and cutting performance directly affect the component surface roughness, material removal rate and form accuracy control, etc. In this paper, a multiscale multiphysics oriented approach to modeling and analysis is presented particularly on tooling performance in micro drilling processes. The process optimization is also taken account based on establishing the intrinsic relationship between process parameters and cutting performance. The modeling and analysis are evaluated and validated through well-designed machining trials, and further supported by metrology measurements and simulations. The paper is concluded with a further discussion on the potential and application of the approach for broad micro manufacturing purposes.

  11. Comparative aspects about the studying methods of cast irons machinability, based on the tool wear

    NASA Astrophysics Data System (ADS)

    Carausu, C.; Pruteanu, O.

    2016-08-01

    The paper presents some considerations of the authors, regarding the studying methods of the cast irons machinability, based on the tools wear on drilling operations. Are described the conditions in which the experimental researches were conducted, intended to offer an overview on drilling machinability of some cast irons categories. It is presented a comparison between long-term methods and short-term methods, for determining the optimal speed chipping of a grey cast iron with lamellar graphite, with average values of tensile strength. Are described: the research methodology, obtained results and conclusions drawn after the results analysis.

  12. Effect of Decreasing of Cobalt Content in Properties for Diamond/Cemented Carbide Tools

    SciTech Connect

    Waratta, A.; Hamdi, M.; Ariga, T.

    2010-03-11

    Powder metallurgy plays a role in manufacturing such as automotive and cutting tool applications. Diamond/cemented carbide tools are also made from this technique. Diamond particle and other matrix materials were employed in this study. The purpose is to investigate the physical and mechanical properties of different Cobalt (Co) content samples by using Taguchi's method. The materials used in the experiments were mixed by using a ball-mill machine. The mixed powders were pressed by conventional method. Then the green samples were sintered in a vacuum furnace. After reaching 500 deg. C, the samples were sintered with Argon (Ar) gas. The sintered samples were investigated density by immersion method, porosity by water saturation method, and hardness by Vicker hardness tester. It was found that with 59.5% Co content, plain diamond type, sintering temperature of 950 deg. C, sintering time of 40 minutes, and pressure of 625 MPa, density, porosity, and hardness got the best result in this study. From the Taguchi's analysis, the significant factors effected the performance were composition, sintering temperature, and sintering time.

  13. Modeling and Adhesive Tool Wear in Dry Drilling of Aluminum Alloys

    SciTech Connect

    Girot, F.; Gutierrez-Orrantia, M. E.

    2011-01-17

    One of the challenges in aeronautic drilling operations is the elimination of cutting fluids while maintaining the quality of drilled parts. This paper therefore aims to increase the tool life and process quality by working on relationships existing between drilling parameters (cutting speed and feed rate), coatings and tool geometry. In dry drilling, the phenomenon of Built-Up Layer is the predominant damage mechanism. A model fitting the axial force with the cutting parameters and the damage has been developed. The burr thickness and its dispersion decrease with the feed rate. The current diamond coatings which exhibit a strong adhesion to the carbide substrate can limit this adhesive layer phenomenon. A relatively smooth nano-structured coating strongly limits the development of this layer.

  14. Modeling and Adhesive Tool Wear in Dry Drilling of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Girot, F.; Gutiérrez-Orrantia, M. E.; Calamaz, M.; Coupard, D.

    2011-01-01

    One of the challenges in aeronautic drilling operations is the elimination of cutting fluids while maintaining the quality of drilled parts. This paper therefore aims to increase the tool life and process quality by working on relationships existing between drilling parameters (cutting speed and feed rate), coatings and tool geometry. In dry drilling, the phenomenon of Built-Up Layer is the predominant damage mechanism. A model fitting the axial force with the cutting parameters and the damage has been developed. The burr thickness and its dispersion decrease with the feed rate. The current diamond coatings which exhibit a strong adhesion to the carbide substrate can limit this adhesive layer phenomenon. A relatively smooth nano-structured coating strongly limits the development of this layer.

  15. Aspects of ultra-high-precision diamond machining of RSA 443 optical aluminium

    NASA Astrophysics Data System (ADS)

    Mkoko, Z.; Abou-El-Hossein, K.

    2015-08-01

    Optical aluminium alloys such as 6061-T6 are traditionally used in ultra-high precision manufacturing for making optical mirrors for aerospace and other applications. However, the optics industry has recently witnessed the development of more advanced optical aluminium grades that are capable of addressing some of the issues encountered when turning with single-point natural monocrystalline diamond cutters. The advent of rapidly solidified aluminium (RSA) grades has generally opened up new possibilities for ultra-high precision manufacturing of optical components. In this study, experiments were conducted with single-point diamond cutters on rapidly solidified aluminium RSA 443 material. The objective of this study is to observe the effects of depth of cut and feed rate at a fixed rotational speed on the tool wear rate and resulting surface roughness of diamond turned specimens. This is done to gain further understanding of the rate of wear on the diamond cutters versus the surface texture generated on the RSA 443 material. The diamond machining experiments yielded machined surfaces which are less reflective but with consistent surface roughness values. Cutting tools were observed for wear through scanning microscopy; relatively low wear pattern was evident on the diamond tool edge. The highest tool wear were obtained at higher depth of cut and increased feed rate.

  16. Adaptive tool servo diamond turning for enhancing machining efficiency and surface quality of freeform optics.

    PubMed

    Zhu, Zhiwei; To, Suet

    2015-08-10

    Fast tool servo/ slow tool servo (FTS/STS) diamond turning is a very promising technique for the generation of freeform optics. However, the currently adopted constant scheme for azimuth sampling and side-feeding motion possesses no adaptation to surface shape variation, leading to the non-uniform surface quality and low machining efficiency. To overcome this defect, this paper reports on a novel adaptive tool servo (ATS) diamond turning technique which is essentially based on the novel two-degree-of-freedom (2-DOF) FTS/STS. In the ATS, the sampling interval and the side-feeding motion are actively controlled at any cutting point to adapt the machining process to shape variation of the desired surface, making both the sampling induced interpolation error and the side-feeding induced residual tool mark be within the desired tolerances. Characteristic of the required cutting motion suggests that besides the conventional z-axis servo motion, another servo motion along the x-axis synthesizing by the c-axis is mandatory for implementing the ATS. Comparative studies of surface generation of typical micro-structured surfaces in FTS/STS and ATS are thoroughly conducted both theoretically and experimentally. The result demonstrates that the ATS outperforms the FTS/STS with improved surface quality while simultaneously enhanced machining efficiency.

  17. DIAMONDS: A new Bayesian nested sampling tool. Application to peak bagging of solar-like oscillations

    NASA Astrophysics Data System (ADS)

    Corsaro, E.; De Ridder, J.

    2014-11-01

    Context. Thanks to the advent of the space-based missions CoRoT and NASA's Kepler, the asteroseismology of solar-like oscillations is now at the base of our understanding about stellar physics. The Kepler spacecraft, especially, is releasing excellent photometric observations of more than three years length in high duty cycle, which contain a large amount of information that has not yet been investigated. Aims: To exploit the full potential of Kepler light curves, sophisticated and robust analysis tools are now required more than ever. Characterizing single stars with an unprecedented level of accuracy and subsequently analyzing stellar populations in detail are fundamental to further constrain stellar structure and evolutionary models. Methods: We developed a new code, termed Diamonds, for Bayesian parameter estimation and model comparison by means of the nested sampling Monte Carlo (NSMC) algorithm, an efficient and powerful method very suitable for high-dimensional and multi-modal problems. A detailed description of the features implemented in the code is given with a focus on the novelties and differences with respect to other existing methods based on NSMC. Diamonds is then tested on the bright F8 V star KIC 9139163, a challenging target for peak-bagging analysis due to its large number of oscillation peaks observed, which are coupled to the blending that occurs between ℓ = 2,0 peaks, and the strong stellar background signal. We further strain the performance of the approach by adopting a 1147.5 days-long Kepler light curve, accounting for more than 840 000 data bins in the power spectrum of the star. Results: The Diamonds code is able to provide robust results for the peak-bagging analysis of KIC 9139163, while preserving a considerable computational efficiency for identifying the solution at the same time. We test the detection of different astrophysical backgrounds in the star and provide a criterion based on the Bayesian evidence for assessing the peak

  18. Effect of biomimetic coupling units' morphologies on rolling contact fatigue wear resistance of steel from machine tool rolling tracks

    NASA Astrophysics Data System (ADS)

    Yang, Wanshi; Zhou, Hong; Sun, Liang; Wang, Chuanwei; Chen, Zhikai

    2014-04-01

    The rolling contact fatigue wear resistance plays an important role on ensuring machining precision of machine tool using rolling tracks. Bio-inspired wearable surfaces with the alternated hardness were prepared on the specimen of steel material from machine tool rolling tracks by biomimetic coupling laser remelting method to imitate biological coupling principle. The microstructures and micromorphologies of bionic units in different sizes were characterized by optical microscope. The specimens with bionic units in different sizes and distributions were tested for rolling contact fatigue wear resistance. Combining the finite element analysis and the results of wear tests, a discussion on rolling contact fatigue wear was had. The specimens with bionic units had better rolling contact fatigue wear resistance than the untreated one, while the specimens with bionic units in the alternative depth's distributions present a better rolling contact fatigue wear resistance than the ones with bionic units in the single depth's distribution. It attributed to the alternative distribution made further improvement on the dispersion of depth of stress concentration.

  19. The function of prehistoric lithic tools: a combined study of use-wear analysis and FTIR microspectroscopy.

    PubMed

    Nunziante Cesaro, Stella; Lemorini, Cristina

    2012-02-01

    The application of combined use-wear analysis and FTIR micro spectroscopy for the investigation of the flint and obsidian tools from the archaeological sites of Masseria Candelaro (Foggia, Italy) and Sant'Anna di Oria (Brindisi, Italy) aiming to clarify their functional use is described. The tools excavated in the former site showed in a very high percentage spectroscopically detectable residues on their working edges. The identification of micro deposits is based on comparison with a great number of replicas studied in the same experimental conditions. FTIR data confirmed in almost all cases the use-wear analysis suggestions and added details about the material processed and about the working procedures.

  20. CNC machine tool's wear diagnostic and prognostic by using dynamic Bayesian networks

    NASA Astrophysics Data System (ADS)

    Tobon-Mejia, D. A.; Medjaher, K.; Zerhouni, N.

    2012-04-01

    The failure of critical components in industrial systems may have negative consequences on the availability, the productivity, the security and the environment. To avoid such situations, the health condition of the physical system, and particularly of its critical components, can be constantly assessed by using the monitoring data to perform on-line system diagnostics and prognostics. The present paper is a contribution on the assessment of the health condition of a computer numerical control (CNC) tool machine and the estimation of its remaining useful life (RUL). The proposed method relies on two main phases: an off-line phase and an on-line phase. During the first phase, the raw data provided by the sensors are processed to extract reliable features. These latter are used as inputs of learning algorithms in order to generate the models that represent the wear's behavior of the cutting tool. Then, in the second phase, which is an assessment one, the constructed models are exploited to identify the tool's current health state, predict its RUL and the associated confidence bounds. The proposed method is applied on a benchmark of condition monitoring data gathered during several cuts of a CNC tool. Simulation results are obtained and discussed at the end of the paper.

  1. Modeling of Principal Flank Wear: An Empirical Approach Combining the Effect of Tool, Environment and Workpiece Hardness

    NASA Astrophysics Data System (ADS)

    Mia, Mozammel; Al Bashir, Mahmood; Dhar, Nikhil Ranjan

    2016-06-01

    Hard turning is increasingly employed in machining, lately, to replace time-consuming conventional turning followed by grinding process. An excessive amount of tool wear in hard turning is one of the main hurdles to be overcome. Many researchers have developed tool wear model, but most of them developed it for a particular work-tool-environment combination. No aggregate model is developed that can be used to predict the amount of principal flank wear for specific machining time. An empirical model of principal flank wear (VB) has been developed for the different hardness of workpiece (HRC40, HRC48 and HRC56) while turning by coated carbide insert with different configurations (SNMM and SNMG) under both dry and high pressure coolant conditions. Unlike other developed model, this model includes the use of dummy variables along with the base empirical equation to entail the effect of any changes in the input conditions on the response. The base empirical equation for principal flank wear is formulated adopting the Exponential Associate Function using the experimental results. The coefficient of dummy variable reflects the shifting of the response from one set of machining condition to another set of machining condition which is determined by simple linear regression. The independent cutting parameters (speed, rate, depth of cut) are kept constant while formulating and analyzing this model. The developed model is validated with different sets of machining responses in turning hardened medium carbon steel by coated carbide inserts. For any particular set, the model can be used to predict the amount of principal flank wear for specific machining time. Since the predicted results exhibit good resemblance with experimental data and the average percentage error is <10 %, this model can be used to predict the principal flank wear for stated conditions.

  2. Inhibiting the oxidation of diamond during preparing the vitrified dental grinding tools by depositing a ZnO coating using direct urea precipitation method.

    PubMed

    Wang, Yanhui; Yuan, Yungang; Cheng, Xiaozhe; Li, Xiaohu; Zang, Jianbing; Lu, Jing; Yu, Yiqing; Xu, Xipeng

    2015-08-01

    Oxidation of diamond during the manufacturing of vitrified dental grinding tools would reduce the strength and sharpness of tools. Zinc oxide (ZnO) coating was deposited on diamond particles by urea precipitation method to protect diamond in borosilicate glass. The FESEM results showed that the ZnO coating was formed by plate-shaped particles. According to the TG results, the onset oxidation temperature of the ZnO-coated diamond was about 70 °C higher than the pristine diamond. The EDS results showed that ZnO diffused into the borosilicate glass during sintering. As the result, the bending strength of the composites containing ZnO-coated diamond was increased by 24% compared to that of the composites containing pristine diamond.

  3. Synthesis and Mechanical Wear Studies of Ultra Smooth Nanostructured Diamond (USND) Coatings Deposited by Microwave Plasma Chemical Vapor Deposition with He/H2/CH4/N2 Mixtures

    PubMed Central

    Chowdhury, S.; Borham, J.; Catledge, S. A.; Eberhardt, A. W.; Johnson, P. S.; Vohra, Y. K.

    2008-01-01

    Ultra smooth nanostructured diamond (USND) coatings were deposited by microwave plasma chemical vapor deposition (MPCVD) technique using He/H2/CH4/N2 gas mixture. The RMS surface roughness as low as 4 nm (2 micron square area) and grain size of 5–6 nm diamond coatings were achieved on medical grade titanium alloy. Previously it was demonstrated that the C2 species in the plasma is responsible for the production of nanocrystalline diamond coatings in the Ar/H2/CH4 gas mixture. In this work we have found that CN species is responsible for the production of USND coatings in He/H2/CH4/N2 plasma. It was found that diamond coatings deposited with higher CN species concentration (normalized by Balmer Hα line) in the plasma produced smoother and highly nanostructured diamond coatings. The correlation between CN/Hα ratios with the coating roughness and grain size were also confirmed with different set of gas flows/plasma parameters. It is suggested that the presence of CN species could be responsible for producing nanocrystallinity in the growth of USND coatings using He/H2/CH4/N2 gas mixture. The RMS roughness of 4 nm and grain size of 5–6 nm were calculated from the deposited diamond coatings using the gas mixture which produced the highest CN/Hα species in the plasma. Wear tests were performed on the OrthoPOD®, a six station pin-on-disk apparatus with ultra-high molecular weight polyethylene (UHMWPE) pins articulating on USND disks and CoCrMo alloy disk. Wear of the UHMWPE was found to be lower for the polyethylene on USND than that of polyethylene on CoCrMo alloy. PMID:19112519

  4. Braze bonding of diamond, CBN, sapphire and other non-metallic hard materials for industrial devices

    SciTech Connect

    Beck, A.

    1995-12-31

    The nature of braze bonding by chemical redox reactions causing a diffusion zone on the surface of the nonmetal with the braze alloy is explained briefly. Some technical and economic advantages for tool and device manufacturing are discussed. Samples of monocrystal devices and grinding tools with braze bonded diamond grit demonstrate the potential of this technology particularly for miniaturization. New applications with other hard materials are shown. Wearing tests have proved that the lifetime of tools with brazed on diamonds is several times as long as of conventional ones with formlocked diamonds. The reason for this is explained.

  5. Diamond coated dental bur machining of natural and synthetic dental materials.

    PubMed

    Jackson, M J; Sein, H; Ahmed, W

    2004-12-01

    Diamond coatings are attractive for cutting processes due to their high hardness, low friction coefficient, excellent wear resistance and chemical inertness. The application of diamond coatings on cemented tungsten carbide (WC-Co) burs has been the subject of much attention in recent years in order to improve cutting performance and tool life. WC-Co burs containing 6% Co and 94% WC with an average grain size 1-3 micron were used in this study. In order to improve the adhesion between diamond and the bur it is necessary to etch away the surface Co to prepare it for subsequent diamond growth. Hot filament chemical vapour deposition (H.F.C.V.D.) with a modified vertical filament arrangement has been employed for the deposition of diamond films. Diamond film quality and purity has been characterised using scanning electron microscopy (S.E.M.) and micro-Raman spectroscopy. The performance of diamond coated WC-Co burs, uncoated WC-Co burs, and diamond embedded (sintered) burs have been compared by drilling a series of holes into various materials such as human teeth, and model tooth materials such as borosilicate glass and acrylic. Flank wear has been used to assess the wear rates of the burs when machining natural and synthetic dental materials such as those described above.

  6. Application of surface analysis to solve problems of wear

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1981-01-01

    Results are presented for the use of surface analytical tools including field ion microscopy, Auger emission spectroscopy analysis (AES), cylindrical mirror Auger analysis and X-ray photoelectron spectroscopy (XPS). Data from the field ion microscope reveal adhesive transfer (wear) at the atomic level with the formation of surface compounds not found in the bulk, and AES reveals that this transfer will occur even in the presence of surface oxides. Both AES and XPS reveal that in abrasive wear with silicon carbide and diamond contacting the transition metals, the surface and the abrasive undergo a chemical or structural change which effects wear. With silicon carbide, silicon volatilizes leaving behind a pseudo-graphitic surface and the surface of diamond is observed to graphitize.

  7. The function of prehistoric lithic tools: a combined study of use-wear analysis and FTIR microspectroscopy.

    PubMed

    Nunziante Cesaro, Stella; Lemorini, Cristina

    2012-02-01

    The application of combined use-wear analysis and FTIR micro spectroscopy for the investigation of the flint and obsidian tools from the archaeological sites of Masseria Candelaro (Foggia, Italy) and Sant'Anna di Oria (Brindisi, Italy) aiming to clarify their functional use is described. The tools excavated in the former site showed in a very high percentage spectroscopically detectable residues on their working edges. The identification of micro deposits is based on comparison with a great number of replicas studied in the same experimental conditions. FTIR data confirmed in almost all cases the use-wear analysis suggestions and added details about the material processed and about the working procedures. PMID:22074884

  8. Modeling the milling tool wear by using an evolutionary SVM-based model from milling runs experimental data

    NASA Astrophysics Data System (ADS)

    Nieto, Paulino José García; García-Gonzalo, Esperanza; Vilán, José Antonio Vilán; Robleda, Abraham Segade

    2015-12-01

    The main aim of this research work is to build a new practical hybrid regression model to predict the milling tool wear in a regular cut as well as entry cut and exit cut of a milling tool. The model was based on Particle Swarm Optimization (PSO) in combination with support vector machines (SVMs). This optimization mechanism involved kernel parameter setting in the SVM training procedure, which significantly influences the regression accuracy. Bearing this in mind, a PSO-SVM-based model, which is based on the statistical learning theory, was successfully used here to predict the milling tool flank wear (output variable) as a function of the following input variables: the time duration of experiment, depth of cut, feed, type of material, etc. To accomplish the objective of this study, the experimental dataset represents experiments from runs on a milling machine under various operating conditions. In this way, data sampled by three different types of sensors (acoustic emission sensor, vibration sensor and current sensor) were acquired at several positions. A second aim is to determine the factors with the greatest bearing on the milling tool flank wear with a view to proposing milling machine's improvements. Firstly, this hybrid PSO-SVM-based regression model captures the main perception of statistical learning theory in order to obtain a good prediction of the dependence among the flank wear (output variable) and input variables (time, depth of cut, feed, etc.). Indeed, regression with optimal hyperparameters was performed and a determination coefficient of 0.95 was obtained. The agreement of this model with experimental data confirmed its good performance. Secondly, the main advantages of this PSO-SVM-based model are its capacity to produce a simple, easy-to-interpret model, its ability to estimate the contributions of the input variables, and its computational efficiency. Finally, the main conclusions of this study are exposed.

  9. Performance evaluation and optimization of a fast tool servo for single point diamond turning machines

    SciTech Connect

    Miller, A.C. Jr.; Cuttino, J.F.

    1997-08-01

    This paper describes a new, fast tool servo system for fabricating non-rotationally symmetric components using single point diamond turning machines. A prototype, designed for flexible interfacing to typical machine tool controllers, will be described along with performance testing data of tilted flat and off-axis conic sections. Evaluation data show that servo produced surfaces have an rms roughness less than 175 angstroms (2-200 {mu}m spatial filter). Techniques for linearizing the hysteretic effects in the piezoelectric actuator are also discussed. The nonlinear effects due to hysteresis are reduced using a dynamic compensator module in conjunction with a linear controller. The compensator samples the hysteretic voltage/displacement relation in real time and modifies the effective gain accordingly. Simulation results indicate that errors in the performance of the system caused by hysteresis can be compensated and reduced by 90%. Experimental implementation results in 80% reduction in motion error caused by hysteresis, but peak-to- valley errors are limited by side effects from the compensation. The uncompensated servo system demonstrated a peak-to-valley error of less than 0.80 micrometer for an off-axis conic section turned on-axis.

  10. Fabrication of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology

    NASA Astrophysics Data System (ADS)

    Luo, Sheng-Yih; Yu, Tsung-Han; Hu, Yuh-Chung

    2007-06-01

    A manufacturing process of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology is reported here. The thickness of JSR THB-151N resist coated on an aluminum alloy substrate for micro lithography can reach up to 110 µm. During the lithography, different geometrical photomasks were used to create specific design patterns of the resist mold on the substrate. Micro roots, made by electrolytic machining on the substrate with guidance of the resist mold, can improve the adhesion of micro nickel abrasive pellets electroplated on the substrate. During the composite electroforming, the desired hardness of the nickel matrix inside the micro diamond abrasive pellets can be obtained by the addition of leveling and stress reducing agents. At moderate blade agitation and ultrasonic oscillation, higher concentration and more uniform dispersion of diamond powders deposited in the nickel matrix can be achieved. With these optimal experiment conditions of this fabrication process, the production of micro nickel/diamond abrasive pellet array lapping tools is demonstrated.

  11. Tribological Characteristics and Applications of Superhard Coatings: CVD Diamond, DLC, and c-BN

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Murakawa, Masao; Watanabe, Shuichi; Takeuchi, Sadao; Wu, Richard L. C.

    1999-01-01

    Results of fundamental research on the tribological properties of chemical-vapor-deposited (CVD) diamond, diamondlike carbon, and cubic boron nitride films in sliding contact with CVD diamond in ultrahigh vacuum, dry nitrogen, humid air, and water are discussed. Furthermore, the actual and potential applications of the three different superhard coatings in the field of tribology technology, particularly for wear parts and tools, are reviewed.

  12. Discrimination of surface wear on obsidian tools using LSCM and RelA: pilot study results (area-scale analysis of obsidian tool surfaces).

    PubMed

    Stemp, W James; Chung, Steven

    2011-01-01

    This pilot study tests the reliability of laser scanning confocal microscopy (LSCM) to quantitatively measure wear on experimental obsidian tools. To our knowledge, this is the first use of confocal microscopy to study wear on stone flakes made from an amorphous silicate like obsidian. Three-dimensional surface roughness or texture area scans on three obsidian flakes used on different contact materials (hide, shell, wood) were documented using the LSCM to determine whether the worn surfaces could be discriminated using area-scale analysis, specifically relative area (RelA). When coupled with the F-test, this scale-sensitive fractal analysis could not only discriminate the used from unused surfaces on individual tools, but was also capable of discriminating the wear histories of tools used on different contact materials. Results indicate that such discriminations occur at different scales. Confidence levels for the discriminations at different scales were established using the F-test (mean square ratios or MSRs). In instances where discrimination of surface roughness or texture was not possible above the established confidence level based on MSRs, photomicrographs and RelA assisted in hypothesizing why this was so. PMID:21674537

  13. Discrimination of surface wear on obsidian tools using LSCM and RelA: pilot study results (area-scale analysis of obsidian tool surfaces).

    PubMed

    Stemp, W James; Chung, Steven

    2011-01-01

    This pilot study tests the reliability of laser scanning confocal microscopy (LSCM) to quantitatively measure wear on experimental obsidian tools. To our knowledge, this is the first use of confocal microscopy to study wear on stone flakes made from an amorphous silicate like obsidian. Three-dimensional surface roughness or texture area scans on three obsidian flakes used on different contact materials (hide, shell, wood) were documented using the LSCM to determine whether the worn surfaces could be discriminated using area-scale analysis, specifically relative area (RelA). When coupled with the F-test, this scale-sensitive fractal analysis could not only discriminate the used from unused surfaces on individual tools, but was also capable of discriminating the wear histories of tools used on different contact materials. Results indicate that such discriminations occur at different scales. Confidence levels for the discriminations at different scales were established using the F-test (mean square ratios or MSRs). In instances where discrimination of surface roughness or texture was not possible above the established confidence level based on MSRs, photomicrographs and RelA assisted in hypothesizing why this was so.

  14. Frictional heating and convective cooling of polycrystalline diamond drag tools during rock cutting

    SciTech Connect

    Ortega, A.; Glowka, D.A.

    1982-01-01

    A numerical-analytical model is developed to predict temperatures in stud-mounted polycrystalline diamond compact (PDC) drag tools during rock cutting. Experimental measurements of the convective heat transfer coefficient for PDC cutters are used in the model to predict temperatures under typical drilling conditions with fluid flow. The analysis compares favorably with measurements of frictional temperatures in controlled cutting tests on Tennessee marble. It is shown that mean cutter wearflat temperatures can be maintained below the critical value of 750{sup 0}C only under conditions of low friction at the cutter/rock interface. This is true, regardless of the level of convective cooling. In fact, a cooling limit is established above which increases in convective cooling do not further reduce cutter temperatures. The ability of liquid drilling fluids to reduce interface friction is thus shown to be far more important in preventing excessive temperatures than their ability to provide cutter cooling. Due to the relatively high interface friction developed under typical air drilling conditions, it is doubtful that temperatures can be kept subcritical at high rotary speeds in some formations when air is employed as the drilling fluid, regardless of the level of cooling achieved.

  15. Bits with diamond-coated inserts reduce gauge problems

    SciTech Connect

    Eckstrom, D. )

    1991-06-17

    In highly abrasive formations, failure of the gauge row cutters on tungsten carbide insert bits may occur rapidly, resulting in short bit runs, poor performance, and undergauge hole. In certain applications, polycrystalline diamond (PCD) enhanced insert bits have longer bit runs and maintain an in-gauge hole which reduces reaming time and wear on downhole equipment. These bits with PCD-coated inserts have reduced drilling costs in several areas of Canada. PCD has been applied to rock drilling tools for several years because of its high wear resistance. Polycrystalline diamond compact (PDC) bits use polycrystalline diamonds formed in flat wafers applied to the flat surfaces on carbide inserts. The flat PDC cutters drill by shearing the formation. Smith International Canada Ltd. developed a patented process to apply PCD to curved surfaces, which now allows PCD-enhanced inserts to be used for percussion and rotary cone applications. These diamond-enhanced inserts combine the wear resistance properties of diamond with the durability of tungsten carbide.

  16. Multi-sensor integration for on-line tool wear estimation through radial basis function networks and fuzzy neural network.

    PubMed

    Kuo, R J.; Cohen, P H.

    1999-03-01

    On-line tool wear estimation plays a very critical role in industry automation for higher productivity and product quality. In addition, appropriate and timely decision for tool change is significantly required in the machining systems. Thus, this paper is dedicated to develop an estimation system through integration of two promising technologies, artificial neural networks (ANN) and fuzzy logic. An on-line estimation system consisting of five components: (1) data collection; (2) feature extraction; (3) pattern recognition; (4) multi-sensor integration; and (5) tool/work distance compensation for tool flank wear, is proposed herein. For each sensor, a radial basis function (RBF) network is employed to recognize the extracted features. Thereafter, the decisions from multiple sensors are integrated through a proposed fuzzy neural network (FNN) model. Such a model is self-organizing and self-adjusting, and is able to learn from the experience. Physical experiments for the metal cutting process are implemented to evaluate the proposed system. The results show that the proposed system can significantly increase the accuracy of the product profile.

  17. Chemical-Vapor-Deposited Diamond Film

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    This chapter describes the nature of clean and contaminated diamond surfaces, Chemical-vapor-deposited (CVD) diamond film deposition technology, analytical techniques and the results of research on CVD diamond films, and the general properties of CVD diamond films. Further, it describes the friction and wear properties of CVD diamond films in the atmosphere, in a controlled nitrogen environment, and in an ultra-high-vacuum environment.

  18. Active wear and failure mechanisms of TiN-coated high speed steel and TiN-coated cemented carbide tools when machining powder metallurgically made stainless steels

    SciTech Connect

    Jiang, L.; Haenninen, H.; Paro, J.; Kauppinen, V.

    1996-09-01

    In this study, active wear and failure mechanisms of both TiN-coated high speed steel and TiN-coated cemented carbide tools when machining stainless steels made by powder metallurgy in low and high cutting speed ranges, respectively, have been investigated. Abrasive wear mechanisms, fatigue-induced failure, and adhesive and diffusion wear mechanisms mainly affected the tool life of TiN-coated high speed steel tools at cutting speeds below 35 m/min, between 35 and 45 m/min, and over 45 m/min, respectively. Additionally, fatigue-induced failure was active at cutting speeds over 45 m/min in the low cutting speed range when machining powder metallurgically made duplex stainless steel 2205 and austenitic stainless steel 316L. In the high cutting speed range, from 100 to 250 m/min, fatigue-induced failure together with diffusion wear mechanism, affected the tool life of TiN-coated cemented carbide tools when machining both 316L and 2205 stainless steels. It was noticed that the tool life of TiN-coated high speed steel tools used in the low cutting speed range when machining 2205 steel was longer than that when machining 316L steel, whereas the tool life of TiN-coated cemented carbide tools used in the high cutting speed range when machining 316L steel was longer than that when machining 2205 steel.

  19. Optimization and Analysis of Nanocrystalline Diamond Coated Micro End Mills

    NASA Astrophysics Data System (ADS)

    Torres, Christopher D.

    This study compares the wear and performance of nanocrystalline diamond (NCD) coated and uncoated tungsten carbide (WC) micro end mills when machining 6061-T6 aluminum. Images of the tool profiles before and after milling are used to track changes in geometry caused by tool wear. Tool performance was characterized by the magnitude of cutting and thrust forces acting on 300 mum diameter end mills and through imaging and analysis of the tool and workpiece surfaces. Thin NCD coatings (<300 nm) allowed for an average of approximately 30 mm of milling before cutting edge fracture. Before edge fracture, the NCD coated tools produced highly uniform, burr free channels. In contrast, significant burring and surface irregularities were evident when using the uncoated tools. Even after cutting edge fracture, the NCD coated tools continued to produce cleaner channels with a lower amount of burring than the uncoated tools but fractured much more severely. However, NCD remaining within the tools' flutes resulted in lower cutting forces due to a reduced effective friction coefficient (friction and adhesion) between the tool surface and the cut chip. Carbon ion implantation (CII), one method to prevent the severe edge failure experienced by the NCD coated end mills, was used as a surface preparation technique to enhance both the cutting edge wear resistance and to increase the nucleation and growth of the diamond coating. Initial milling tests from the carbon ion implanted tools have indicated a drastic improvement in resistance to cutting edge fracture. The implantation of ions into the tool's surface induced compressive stress on the cutting edge, thereby increasing tool resistance. However, the inconsistency of CII has thus far resulted in poorly adhered diamond coatings. Additional stress analysis on the cutting edge has revealed the formation of detrimental bending stresses present during micro milling with an NCD coating. Increasing the cutting edge radius and the coating

  20. Superhard material comparable in hardness to diamond

    SciTech Connect

    Badzian, A.R.

    1988-12-19

    Superhard boron suboxides, with hardness close to that of diamond, were synthesized from boron/boron oxide mixtures. Such hardness is expected when a material's molar volume approaches the value characteristic for diamond. These materials consist of boron-rich phases belonging to the boron-oxygen system. The phase which contains 4 at. % oxygen and a crystal structure related to ..beta..rhombohedral boron can scratch diamond faces. During scratching of diamond the suboxide is worn also, and the wear debris is amorphized. Wear on the lt. slash/100/ diamond faces results from a cleavage mechanism which leaves a rough surface covered with cleaved lt. slash/111/ microfaces. The lt. slash/100/ faces are more easily abraded than the lt. slash/111/ diamond faces. Wear on lt. slash/111/ faces consumes much more energy and leaves grooves of plastically deformed diamond.

  1. Superhard material comparable in hardness to diamond

    NASA Astrophysics Data System (ADS)

    Badzian, Andrzej R.

    1988-12-01

    Superhard boron suboxides, with hardness close to that of diamond, were synthesized from boron/boron oxide mixtures. Such hardness is expected when a material's molar volume approaches the value characteristic for diamond. These materials consist of boron-rich phases belonging to the boron-oxygen system. The phase which contains 4 at. % oxygen and a crystal structure related to β-rhombohedral boron can scratch diamond faces. During scratching of diamond the suboxide is worn also, and the wear debris is amorphized. Wear on the {100} diamond faces results from a cleavage mechanism which leaves a rough surface covered with cleaved {111} microfaces. The {100} faces are more easily abraded than the {111} diamond faces. Wear on {111} faces consumes much more energy and leaves grooves of plastically deformed diamond.

  2. Response Surface Methodology Approach on Effect of Cutting Parameter on Tool Wear during End Milling of High Thermal Conductivity Steel -150 (HTCS-150)

    NASA Astrophysics Data System (ADS)

    Mohd Hadzley, A. B.; Mohd Azahar, W. M. Y. Wan; Izamshah, R.; Mohd Shahir, K.; Mohd Amran, A.; Anis Afuza, A.

    2016-02-01

    This paper presents a study of development the tool life's mathematical model during the milling process on High Thermal Conductivity Steel 150 (HTCS-150) 56 HRC. Using response surface methodology, the mathematical models for tool life have been developed in terms of cutting speed, feed rate and depth of cut. Box-Behnken techniques is a part of Response Surface Methodology (RSM) has been used to carry out the work plan to predict, the tool wear and generate the numerical equation in relation to independent variable parameters by Design Expert software. Dry milling experiments were conducted by using two levels of cutting speed, feed rate and depth of cut. In this study, the variable for the cutting speed, feed rate and depth of cut were in the range of 484-553 m/min, 0.31-0.36 mm/tooth, and 0.1-0.5 mm, width of cut is constantly 0.01mm per passes. The tool wear was measured using tool maker microscope. The effect of input factors that on the responds were identified by using mean of ANOVA. The responds of tool wear then simultaneously optimized. The validation of the test reveals the model accuracy 5% and low tool wear under same experimental condition.

  3. Investigation of surface roughness and tool wear length with varying combination of depth of cut and feed rate of Aluminium alloy and P20 steel machining.

    NASA Astrophysics Data System (ADS)

    Varmma a/l Suparmaniam, Madan; Razlan Yusoff, Ahmad

    2016-02-01

    High-speed milling technique is often used in many industries to boost productivity of the manufacturing of high-technology components. The occurrence of wear highly limits the efficiency and accuracy of high- speed milling operations. In this paper, analysis of high-speed milling process parameters such as material removal rate, cutting speed, feed rate and depth of cut carried out by implemented to conventional milling. This experiment investigate the effects of varying combination of depth of cut and feed rate to tool wear rate length using metallurgical microscope and surface roughness using portable surface roughness tester after end milling of Aluminium and P20 steel. Results showed that feed rate significantly influences the surface roughness value while depth of cut does not as the surface roughness value keep increasing with the increase of feed rate and decreasing depth of cut. Whereas, tool wear rate almost remain unchanged indicates that material removal rate strongly contribute the wear rate. It believe that with no significant tool wear rate the results of this experiment are useful by showing that HSM technique is possible to be applied in conventional machine with extra benefits of high productivity, eliminating semi-finishing operation and reducing tool load for finishing.

  4. Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel

    NASA Astrophysics Data System (ADS)

    Çiçek, Adem; Kara, Fuat; Kıvak, Turgay; Ekici, Ergün; Uygur, İlyas

    2015-11-01

    In this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 °C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.

  5. Machining graphite composites with polycrystalline diamond end mills

    NASA Astrophysics Data System (ADS)

    Kohkonen, Kent E.; Anderson, Scott; Strong, A. B.

    One area of focus in developing light-strong materials has been the development of graphite/epoxy composites. The graphite/epoxy materials have created challenges in the area of fabrication and machining. The research objective was to determine if cutting tool material and style of cutting edge showed any significant differences in tool life. The cutting tool materials and cutter styles included helical carbide-end mills and straight and helical polycrystalline diamond-end mill cutters. The experimental design was developed using a fractional factorial design running twelve tests. Results were taken from cutting tool flank edge wear, composite part surface finish, and visual delamination of the part.

  6. Discrete element thermomechanical modelling of rock cutting with valuation of tool wear

    NASA Astrophysics Data System (ADS)

    Rojek, Jerzy

    2014-05-01

    The paper presents a thermomechanical discrete element model of rock cutting process. The thermomechanical formulation of the discrete element method considers mechanical and thermal phenomena and their reciprocal influence. The thermal model developed for transient heat conduction problems takes into account conductive heat transfer at the contact between particles and convection on the free surface. The thermal and mechanical problems are coupled by consideration of: (1) heat generated due to friction which is calculated in the mechanical problem and passed to the thermal solution, (2) influence of thermal expansion on mechanical interaction between particles. Estimation of temperature dependent wear has been included into the contact model. The coupled problem is solved using the staggered scheme.The thermomechanical algorithm has been implemented in a discrete element program and applied to simulation of rock cutting with single pick of a dredge cutter head. Numerical results confirm good performance of the developed algorithm.

  7. Carbon-Based Wear Coatings: Properties and Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2003-01-01

    The technical function of numerous engineering systems - such as vehicles, machines, and instruments - depends on the processes of motion and on the surface systems. Many processes in nature and technology depend on the motion and dynamic behavior of solids, liquids, and gases. Smart surface systems are essential because of the recent technological push toward higher speeds, loads, and operating temperatures; longer life; lighter weight and smaller size (including nanotechnology); and harsh environments in mechanical, mechatronic, and biomechanical systems. If proper attention is not given to surface systems, then vehicles, machines, instruments, and other technical systems could have short lives, consume excessive energy, experience breakdowns, result in liabilities, and fail to accomplish their missions. Surface systems strongly affect our national economy and our lifestyles. At the NASA Glenn Research Center, we believe that proper attention to surface systems, especially in education, research, and application, could lead to economic savings of between 1.3 and 1.6 percent of the gross domestic product. Wear coatings and surface systems continue to experience rapid growth as new coating and surface engineering technologies are discovered, more cost-effective coating and surface engineering solutions are developed, and marketers aggressively pursue, uncover, and exploit new applications for engineered surface systems in cutting tools and wear components. Wear coatings and smart surface systems have been used widely in industrial, consumer, automotive, aerospace, and biomedical applications. This presentation expresses the author's views of and insights into smart surface systems in wear coatings. A revolution is taking place in carbon science and technology. Diamond, an allotrope of carbon, joins graphite, fullerenes, and nanotubes as its major pure carbon structures. It has a unique combination of extreme properties: hardness and abrasion resistance; adhesion

  8. FIBROUS MONOLITH WEAR RESISTANT COMPONENTS FOR THE MINING INDUSTRY

    SciTech Connect

    Mark J. Rigali; Kenneth L. Knittel; Mike L. Fulcher

    2002-03-01

    During this reporting period, work continued on development of formulations using the materials identified as contenders for the fibrous monolith wear resistant components. The FM structures fabricated were: diamond/WC-Co, B{sub 4}C/WC-Co, TiB{sub 2}/WC-Co, WC-Co/Co, WC-Co/WC-Co. Results of our consolidation densification studies on these systems lead to the down-selection of WC-Co/WC-Co, WC-Co/Co and diamond/WC-Co for further development for mining applications including drill bit inserts, roof bit inserts, radial tools conical tools and wear plates (WC-Co based system only) for earth moving equipment. Prototype component fabrication focused on the fabrication of WC-Co/WC-Co FM conical tools, diamond/WC-Co coated drill bit insert prototypes. Fabrication of WC-Co/WC-Co FM insert prototypes for a grader blade is also underway. ACR plans to initiate field-testing of the drill bit insert prototypes and the grader blade insert this summer (2002). The first WC-Co/WC-Co FM conical tool prototypes were sent to Kennametal for evaluation towards the end of the current reporting period.

  9. A Multiple-Regression Model for Monitoring Tool Wear with a Dynamometer in Milling Operations

    ERIC Educational Resources Information Center

    Chen, Jacob C.; Chen, Joseph C.

    2004-01-01

    A major goal of the manufacturing industry is increasing product quality. The quality of a product is strongly associated with the condition of the cutting tool that produced it. Catching poor tool conditions early in the production will help reduce defects. However, with current CNC technology, manufacturers still rely mainly on the operator's…

  10. Isomekes: A fundamental tool to determine the formation pressure for diamond-inclusion pairs

    NASA Astrophysics Data System (ADS)

    Alvaro, Matteo; Angel, Ross; Mazzucchelli, Mattia; Nestola, Fabrizio; Domeneghetti, Chiara

    2014-05-01

    Because diamond is almost chemically pure carbon and extremely chemically inert, the structure and chemistry of diamond reveals very little about its conditions of formation. Much of what is believed about the genesis and distribution of diamond in the Earth's mantle has therefore been deduced indirectly from the characterisation of its mineral inclusions. The possible depths of entrapment of an inclusion within a host phase (and hence the depth of growth of the host diamond) can be determined if (1) the final pressure of the inclusion can be measured, (2) the Equations of State (EoS) of the host and inclusion phases are known, and (3) the elastic interaction between the host and inclusion can be calculated without gross assumptions. Given knowledge of all three, an isomeke line in P-T space (from the Greek "equal" and "length", Adams et al. 1975) can be calculated. The isomeke defines the conditions at which the host and inclusion would have had the same P, T and volume, and thus represents possible entrapment conditions. The recent application (Nestola et al. 2011; Howell et al. 2012) of in-situ diffraction techniques to the measurement of entrapped inclusions provides accurate final inclusion pressures. We have reformulated the elasticity problem so that, unlike previous work, these calculations can be performed with any form of equation of state and thermal expansion, and are not restricted to linear elasticity or just invertible EoS. This alone has significant advantages in the precision of the calculated depths of formation. Numerical calculations have been performed with a new module of EoS routines (Angel et al. 2014) that has been added to the publicly-available CrysFML library. The question remains as to what uncertainties in calculated depths of formation arise from uncertainties in experimentally-determined EoS. We will present two geologically-relevant examples, for olivine and garnet in diamond. Our calculations show that there is still a clear need

  11. Ductile cutting of silicon microstructures with surface inclination measurement and compensation by using a force sensor integrated single point diamond tool

    NASA Astrophysics Data System (ADS)

    Chen, Yuan-Liu; Cai, Yindi; Shimizu, Yuki; Ito, So; Gao, Wei; Ju, Bing-Feng

    2016-02-01

    This paper presents a measurement and compensation method of surface inclination for ductile cutting of silicon microstructures by using a diamond tool with a force sensor based on a four-axis ultra-precision lathe. The X- and Y-directional inclinations of a single crystal silicon workpiece with respect to the X- and Y-motion axes of the lathe slides were measured respectively by employing the diamond tool as a touch-trigger probe, in which the tool-workpiece contact is sensitively detected by monitoring the force sensor output. Based on the measurement results, fabrication of silicon microstructures can be thus carried out directly along the tilted silicon workpiece by compensating the cutting motion axis to be parallel to the silicon surface without time-consuming pre-adjustment of the surface inclination or turning of a flat surface. A diamond tool with a negative rake angle was used in the experiment for superior ductile cutting performance. The measurement precision by using the diamond tool as a touch-trigger probe was investigated. Experiments of surface inclination measurement and ultra-precision ductile cutting of a micro-pillar array and a micro-pyramid array with inclination compensation were carried out respectively to demonstrate the feasibility of the proposed method.

  12. Workshop on diamond and diamond-like-carbon films for the transportation industry

    SciTech Connect

    Nichols, F.A.; Moores, D.K.

    1993-01-01

    Applications exist in advanced transportation systems as well as in manufacturing processes that would benefit from superior tribological properties of diamond, diamond-like-carbon and cubic boron nitride coatings. Their superior hardness make them ideal candidates as protective coatings to reduce adhesive, abrasive and erosive wear in advanced diesel engines, gas turbines and spark-ignited engines and in machining and manufacturing tools as well. The high thermal conductivity of diamond also makes it desirable for thermal management not only in tribological applications but also in high-power electronic devices and possibly large braking systems. A workshop has been recently held at Argonne National Laboratory entitled ``Diamond and Diamond-Like-Carbon Films for Transportation Applications`` which was attended by 85 scientists and engineers including top people involved in the basic technology of these films and also representatives from many US industrial companies. A working group on applications endorsed 18 different applications for these films in the transportation area alone. Separate abstracts have been prepared.

  13. Wear and Adhesive Failure of Al2O3 Powder Coating Sprayed onto AISI H13 Tool Steel Substrate

    NASA Astrophysics Data System (ADS)

    Amanov, Auezhan; Pyun, Young-Sik

    2016-07-01

    In this study, an alumina (Al2O3) ceramic powder was sprayed onto an AISI H13 hot-work tool steel substrate that was subjected to sanding and ultrasonic nanocrystalline surface modification (UNSM) treatment processes. The significance of the UNSM technique on the adhesive failure of the Al2O3 coating and on the hardness of the substrate was investigated. The adhesive failure of the coating sprayed onto sanded and UNSM-treated substrates was investigated by a micro-scratch tester at an incremental load. It was found, based on the obtained results, that the coating sprayed onto the UNSM-treated substrate exhibited a better resistance to adhesive failure in comparison with that of the coating sprayed onto the sanded substrate. Dry friction and wear property of the coatings sprayed onto the sanded and UNSM-treated substrates were assessed by means of a ball-on-disk tribometer against an AISI 52100 steel ball. It was demonstrated that the UNSM technique controllably improved the adhesive failure of the Al2O3 coating, where the critical load was improved by about 31%. Thus, it is expected that the application of the UNSM technique to an AISI H13 tool steel substrate prior to coating may delay the adhesive failure and improve the sticking between the coating and the substrate thanks to the modified and hardened surface.

  14. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2001-01-01

    An overview of the industrial diamond industry is provided. More than 90 percent of the industrial diamond consumed in the U.S. and the rest of the world is manufactured diamond. Ireland, Japan, Russia, and the U.S. produce 75 percent of the global industrial diamond output. In 2000, the U.S. was the largest market for industrial diamond. Industrial diamond applications, prices for industrial diamonds, imports and exports of industrial diamonds, the National Defense Stockpile of industrial diamonds, and the outlook for the industrial diamond market are discussed.

  15. Wear behavior of Al{sub 2}O{sub 3}, Si{sub 3}N{sub 4} and CBN cutting tool materials at high sliding speed

    SciTech Connect

    Rigaut, B.; Chen, Y.M.; Saint Chely, J.

    1994-06-01

    Tool materials based on Al{sub 2}O{sub 3}, Si{sub 3}N{sub 4} and CBN were tested on a pin-on-disk wear machine with an AISI 4041 steel counterface under low pressure (0.25 MPa) and at high sliding speed ranging from 10 m/s to 50 m/s. The humidity of the laboratory was controlled at 50 percent during the wear tests. It was found that the wear rate of CBN was the smallest among the material at all speeds tested. The wear rate of Si{sub 3}N{sub 4} decreased from 7 X 10{sup -7} mm{sup 3}/N.m to 2 X 10{sup -7} mm{sup 3}/N.m when the speed increased from 10 m/s to 30 m/s. It then increased to 6.3 X 10{sup -7} mm{sup 3}/N.m at 50 m/s. The wear rate of the ZrO{sub 2} reinforced Al{sub 2}O{sub 3} was quite high (1.5 X 10{sup -6} mm{sup 3}/N.m) at 10 m/s, which was more than twice that of SiC whisker-reinforced Al{sub 2}O{sub 3} and other alumina ceramics tested in previous studies. The difference of the wear resistance between the two Al{sub 2}O{sub 3} based materials should be due to the additional phase of ZrO{sub 2} and SiC whiskers. The wear results have been compared with those of milling tests with the same counterface at a speed included in the investigated range on the pin-on-disk tribometer. A correlation was found between the wear results and the tool life in the milling test for CBN, Si{sub 3}N{sub 4}, and SiC whisker-reinforced Al{sub 2}O{sub 3}. 8 refs., 14 figs., 1 tab.

  16. Ultralow wear of gallium nitride

    NASA Astrophysics Data System (ADS)

    Zeng, Guosong; Tan, Chee-Keong; Tansu, Nelson; Krick, Brandon A.

    2016-08-01

    Here, we reveal a remarkable (and surprising) physical property of GaN: it is extremely wear resistant. In fact, we measured the wear rate of GaN is approaching wear rates reported for diamond. Not only does GaN have an ultralow wear rate but also there are quite a few experimental factors that control the magnitude of its wear rate, further contributing to the rich and complex physics of wear of GaN. Here, we discovered several primary controlling factors that will affect the wear rate of III-Nitride materials: crystallographic orientation, sliding environment, and coating composition (GaN, InN and InGaN). Sliding in the ⟨ 1 2 ¯ 10 ⟩ is significantly lower wear than ⟨ 1 1 ¯ 00 ⟩ . Wear increases by 2 orders of magnitude with increasing humidity (from ˜0% to 50% RH). III-Nitride coatings are promising as multifunctional material systems for device design and sliding wear applications.

  17. The development of plant food processing in the Levant: insights from use-wear analysis of Early Epipalaeolithic ground stone tools.

    PubMed

    Dubreuil, Laure; Nadel, Dani

    2015-11-19

    In recent years, the study of percussive, pounding and grinding tools has provided new insights into human evolution, more particularly regarding the development of technology enabling the processing and exploitation of plant resources. Some of these studies focus on early evidence for flour production, an activity frequently perceived as an important step in the evolution of plant exploitation. The present paper investigates plant food preparation in mobile hunter-gatherer societies from the Southern Levant. The analysis consists of a use-wear study of 18 tools recovered from Ohalo II, a 23 000-year-old site in Israel showing an exceptional level of preservation. Our sample includes a slab previously interpreted as a lower implement used for producing flour, based on the presence of cereal starch residues. The use-wear data we have obtained provide crucial information about the function of this and other percussive tools at Ohalo II, as well as on investment in tool manufacture, discard strategies and evidence for plant processing in the Late Pleistocene. The use-wear analysis indicates that the production of flour was a sporadic activity at Ohalo II, predating by thousands of years the onset of routine processing of plant foods. PMID:26483535

  18. The development of plant food processing in the Levant: insights from use-wear analysis of Early Epipalaeolithic ground stone tools.

    PubMed

    Dubreuil, Laure; Nadel, Dani

    2015-11-19

    In recent years, the study of percussive, pounding and grinding tools has provided new insights into human evolution, more particularly regarding the development of technology enabling the processing and exploitation of plant resources. Some of these studies focus on early evidence for flour production, an activity frequently perceived as an important step in the evolution of plant exploitation. The present paper investigates plant food preparation in mobile hunter-gatherer societies from the Southern Levant. The analysis consists of a use-wear study of 18 tools recovered from Ohalo II, a 23 000-year-old site in Israel showing an exceptional level of preservation. Our sample includes a slab previously interpreted as a lower implement used for producing flour, based on the presence of cereal starch residues. The use-wear data we have obtained provide crucial information about the function of this and other percussive tools at Ohalo II, as well as on investment in tool manufacture, discard strategies and evidence for plant processing in the Late Pleistocene. The use-wear analysis indicates that the production of flour was a sporadic activity at Ohalo II, predating by thousands of years the onset of routine processing of plant foods.

  19. The Effect of the Gas Inlet on the Fluid Field during Fabricating Hfcvd Diamond-Coated Cutting Tools

    NASA Astrophysics Data System (ADS)

    Shen, Bin; Chen, Sulin; Cheng, Lei; Sun, Fanghong

    2014-07-01

    In the present study, the fluid field in a process of fabricating diamond coated cutting tools using the hot filament chemical vapor deposition (HFCVD) method is investigated using the finite volume method (FVM), in which the effects of the inlet height, gas initial velocity, inlet radius and arrangement are illustrated in terms of the gas velocity magnitude and vector distribution near the filaments and the flute surface of cutting tools. In the simulations, the coupling effect of the temperature and the gas field is also considered by simultaneously calculating the temperature distribution. The simulation results suggest that either shortening the distance between the gas inlet and filaments, or increasing the gas initial velocity is helpful for the reactive gas arriving at filaments surface and being dissociated. Furthermore, increasing the inlet area is able to significantly increase the velocity of gas field around the filaments, as well as produce a much more uniform gas velocity field. Based on this conclusion, two novel multi-inlets setups are proposed to further improve the generated gas field and the simulation results show that the most superior gas field can be achieved with the one including 8 larger central inlets and 24 smaller outskirt inlets. Finally, an actual deposition experiment is carried out and its result indicates that adopting the optimized such inlet arrangement could generate a highly uniform and homogeneous growth environment on whole deposition area.

  20. Diamond grooving of rapidly solidified optical aluminium

    NASA Astrophysics Data System (ADS)

    Abou-El-Hossein, Khaled; Hsu, Wei-Yao; Ghobashy, Sameh; Cheng, Yuan-Chieh; Mkoko, Zwelinzima

    2015-10-01

    Traditional optical aluminium grades such as Al 6061 are intensively used for making optical components for applications ranging from mould insert fabrication to laser machine making. However, because of their irregular microstructure and relative inhomogeneity of material properties at micro scale, traditional optical aluminium may exhibit some difficulties when ultra-high precision diamond turned. Inhomogeneity and micro-variation in the material properties combined with uneven and coarse microstructure may cause unacceptable surface finish and accelerated tool wear, especially in grooving operation when the diamond tool edge is fully immersed in the material surface. Recently, new grades of optical aluminium that are featured by their ultra-fine microstructure and improved material properties have been developed to overcome the problem of high tool wear rates. The new aluminium grades have been developed using rapid solidification process which results in extremely small grain sizes combined with improved mechanical properties. The current study is concerned with investigating the performance of single-point diamond turning when grooving two grades of rapidly solidified aluminium (RSA) grades: RSA905 which is a high-alloyed aluminium grade and RSA443 which has a high silicon content. In this study, two series of experiments employed to create radial microgrooves on the two RSA grades. The surface roughness obtained on the groove surface is measured when different combinations of cutting parameters are used. Cutting speed is varied while feed rate and depth of cut were kept constant. The results show that groove surface roughness produced on RSA443 is higher than that obtained on RSA905. Also, the paper reports on the effect of cutting speed on surface roughness for each RSA grade.

  1. Numerical controlled polishing, continued force wear and part correction experiments

    SciTech Connect

    Hannah, P.R.; Day, R.D.; Hatch, D.J.; McClure, E.R.

    1994-09-01

    This abstract reports the near completion of the first phase of this program. It is the aim of this program to provide the operator of a N/C diamond turning machine or N/C grinding machine (jig grinder) with the wear characteristics necessary to achieve uniform material removal. The second phase of this program addresses a different problem, although solving this problem is highly dependent on the results of the first phase. Diamond turned, or any lathe turned surface, exhibits regular tool marks due to the tool passing over the surface being cut. Changes in depth of cut, feed rate and work rpm will change the character of these groves, but will not eliminate them. Optical surfaces produced by this process exhibit increased scattering as the light wavelength decreases limiting their use; at least for optical purposes, to IR and some visible applications. Utilizing wear information gathered in the first part of this program we will attempt to reduce these residual tool marks by polishing. The polishing of diamond turned surfaces is not new. Diamond turned metal surfaces, especially in electroless nickel and high phosphorus nickel electroplate have been polished to improve their scatter characteristics. What we believe is unique is the use of a spherical wheel, rotating on axis and being moved over the part in a prescribed manner by numerical control. Over the past year we have made some major changes in our polishing methods and procedures. We have listed below these changes, as a refresher for the reader as to our previous procedures. These changes will be addressed in the body of the text.

  2. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2003-01-01

    Statistics on the production, consumption, cost, trade, and government stockpile of natural and synthetic industrial diamond are provided. The outlook for the industrial diamond market is also considered.

  3. Assessment of variations in wear test methodology.

    PubMed

    Gouvêa, Cresus V D; Weig, Karin; Filho, Thales R M; Barros, Renata N

    2010-01-01

    The properties of composite resin for dental fillings were improved by development, but its weakness continues to be its wear strength. Several tests have been proposed to evaluate wear in composite resin materials. The aim of this study was to verify how polishing and the type of abrasive can influence the wear rate of composite resin. The test was carried out on two groups. In one group we employed an ormocer and a hybrid composite that was polished group the composite was polished with the same abrasive paper plus a 1 microm and 0.25 microm grit diamond paste. A three-body wear test was performed using the metal sphere of the wear test machine, the composite and an abrasive. A diamond paste and aluminum oxide dispersion were used as abrasive. Analysis of the results showed that there was no difference between polishing techniques, but revealed a difference between abrasives.

  4. Ion-Beam-Induced Luminescence Analysis as Diagnostic Tool for Microstructure Patterning on Diamond by Proton Beam Writing

    NASA Astrophysics Data System (ADS)

    Kada, Wataru; Yokoyama, Akihito; Koka, Masashi; Takano, Katsuyoshi; Satoh, Takahiro; Kamiya, Tomihiro

    2012-06-01

    An in situ diagnostics technique for proton beam writing (PBW) on chemical vapor deposition (CVD) diamond was newly established by developing a method of monochromatic ion-beam-induced luminescence (IBIL) analysis. As a compact optic system of IBIL analysis, a couple of optics including a monochromator and a photon counting photomultiplier were installed on the microbeam line of a 3 MV single-ended accelerator. Changes in the crystal structure of single-crystal CVD diamond were continuously monitored by observing the decay of IBIL at a wavelength related to them. Two-dimensional microscopy images of IBIL were also clearly visualized as patterns on diamond in the postprocess of PBW with the same experimental setup. The total fluence of the proton microbeam was well linked to the photon count of IBIL for the fabrication of micrometer-sized carbonized layers in the CVD diamond crystal.

  5. New profilable bond system for diamond and CBN grinding wheels

    NASA Astrophysics Data System (ADS)

    Macina, R.

    Attempts to use diamond or CBN grinding wheels for full cut or deep cutting processes in the machining of hard materials, were initially limited to grinding wheels coated by electrodeposition. The tool body was provided with the required profile and the diamond or CBN coating was electrodeposited in accordance with known methods. Success could be achieved with these grinding wheels in certain cases. The greater projection of abrasive grit obtained with electrodeposited coatings as opposed to impregnated coatings was removed by subsequent profiling with diamond profile grinding wheels, so that accurate tolerances for workpieces could be achieved up to a certain limit. The grain wear of the engaged tools is uneven and commences in those areas that are subjected to the greatest load such as at the edges or the projected radii so that recoating usually becomes necessary when the coating has worn away at only one point. For all practical purposes this amounts to a new coating. Efforts were therefore directed towards adapting the conventional grinding technique, involving the crushing of a profile onto the wheel periphery with the aid of a crushing device mounted on a grinding machine, to diamond and CBN grinding wheels. A prerequisite for this was to develop a bonding material which could be profiled by crushing. This method opened up new possibilities, particularly for deep and full cut grinding.

  6. Fractal Analysis of Grain Cutting Edge Wear in Superabrasive Grinding

    NASA Astrophysics Data System (ADS)

    Ichida, Yoshio; Sato, Ryunosuke; Fujimoto, Masakazu; Tanaka, Hiromichi

    This paper deals with a fractal analysis of the wear behavior of the grain cutting edges in superabrasive grinding. Fundamental overcut fly grinding experiments for producing individual straight grooves using a grinding tool with multiple grits are carried out to clarify the wear characteristics of the grain cutting edges in the grinding process and then the change in three-dimensional profile of the cutting edge measured with a multiprobe SEM is evaluated on the basis of fractal analysis. The main results are summarized as follows: (1) Fractal dimension for the contour line of the fine cutting edge formed by micro fracture shows a higher value than that of cutting edge formed by attritious wear or large fracture. (2) Fractal dimension for cBN grain cutting edge mainly formed by micro fracture tends to take a higher value than that for diamond grain cutting edge mainly formed by attritious wear. (3) The complex change in shape of the cutting edge with the progress of grinding process can be quantitatively evaluated by means of fractal analysis.

  7. Diamond-modified AFM probes: from diamond nanowires to atomic force microscopy-integrated boron-doped diamond electrodes.

    PubMed

    Smirnov, Waldemar; Kriele, Armin; Hoffmann, René; Sillero, Eugenio; Hees, Jakob; Williams, Oliver A; Yang, Nianjun; Kranz, Christine; Nebel, Christoph E

    2011-06-15

    In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are

  8. The Effect of Friction Stir Processing by Stepped Tools on the Microstructure, Mechanical Properties and Wear Behavior of a Mg-Al-Zn Alloy

    NASA Astrophysics Data System (ADS)

    Arab, Seyed Mohammad; Jahromi, Seyed Ahmad Jenabali; Zebarjad, Seyed Mojtaba

    2016-10-01

    Friction stir processing (FSP) which imposes severe plastic strains has been used as a solid-state process to refine the grain structure of a Mg-Al-Zn alloy and therefore to enhance the strength and wear resistance without significant reduction of ductility. The introduced stepped tools result in more uniform microstructure, and therefore higher mechanical properties, as well as enhanced wear resistance. More passes of FSP could lead to more uniform microstructure and finer grains. The grain size was reduced from above 40 µm to below 4 µm. The pin root hole defect is also reduced during FSP by the stepped tools especially by cylindrical one. Microhardness was increased more than two times compared with the as-received sample. The tensile strength and elongation are almost doubled after different conditions of FSP. Coefficient of friction is reduced to 1/13.3, and weight loss has been reduced to about 50% of initial values after friction stir processing. The obtained results also demonstrated the successful dynamic recrystallization during FSP.

  9. The Effect of Friction Stir Processing by Stepped Tools on the Microstructure, Mechanical Properties and Wear Behavior of a Mg-Al-Zn Alloy

    NASA Astrophysics Data System (ADS)

    Arab, Seyed Mohammad; Jahromi, Seyed Ahmad Jenabali; Zebarjad, Seyed Mojtaba

    2016-08-01

    Friction stir processing (FSP) which imposes severe plastic strains has been used as a solid-state process to refine the grain structure of a Mg-Al-Zn alloy and therefore to enhance the strength and wear resistance without significant reduction of ductility. The introduced stepped tools result in more uniform microstructure, and therefore higher mechanical properties, as well as enhanced wear resistance. More passes of FSP could lead to more uniform microstructure and finer grains. The grain size was reduced from above 40 µm to below 4 µm. The pin root hole defect is also reduced during FSP by the stepped tools especially by cylindrical one. Microhardness was increased more than two times compared with the as-received sample. The tensile strength and elongation are almost doubled after different conditions of FSP. Coefficient of friction is reduced to 1/13.3, and weight loss has been reduced to about 50% of initial values after friction stir processing. The obtained results also demonstrated the successful dynamic recrystallization during FSP.

  10. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2012-01-01

    Estimated 2011 world production of natural and synthetic industrial diamond was about 4.45 billion carats. During 2011, natural industrial diamonds were produced in more than 20 countries, and synthetic industrial diamond was produced in at least 13 countries. About 98 percent of the combined natural and synthetic global output was produced in China, Ireland, Japan, Russia, South Africa and the United States. China is the world's leading producer of synthetic industrial diamond followed by Russia and the United States.

  11. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  12. A novel Mo-W interlayer approach for CVD diamond deposition on steel

    SciTech Connect

    Kundrát, Vojtěch; Sullivan, John; Ye, Haitao; Zhang, Xiaoling; Cooke, Kevin; Sun, Hailin

    2015-04-15

    Steel is the most widely used material in engineering for its cost/performance ratio and coatings are routinely applied on its surface to further improve its properties. Diamond coated steel parts are an option for many demanding industrial applications through prolonging the lifetime of steel parts, enhancement of tool performance as well as the reduction of wear rates. Direct deposition of diamond on steel using conventional chemical vapour deposition (CVD) processes is known to give poor results due to the preferential formation of amorphous carbon on iron, nickel and other elements as well as stresses induced from the significant difference in the thermal expansion coefficients of those materials. This article reports a novel approach of deposition of nanocrystalline diamond coatings on high-speed steel (M42) substrates using a multi-structured molybdenum (Mo) – tungsten (W) interlayer to form steel/Mo/Mo-W/W/diamond sandwich structures which overcome the adhesion problem related to direct magnetron sputtering deposition of pure tungsten. Surface, interface and tribology properties were evaluated to understand the role of such an interlayer structure. The multi-structured Mo-W interlayer has been proven to improve the adhesion between diamond films and steel substrates by acting as an effective diffusion barrier during the CVD diamond deposition.

  13. Wearing gloves in the hospital

    MedlinePlus

    Infection control - wearing gloves; Patient safety - wearing gloves; Personal protective equipment - wearing gloves; PPE - wearing gloves; Nosocomial infection - wearing gloves; Hospital acquired infection - wearing gloves

  14. FIBROUS MONOLITH WEAR RESISTANT COMPONENTS FOR THE MINING INDUSTRY

    SciTech Connect

    Mike L. Fulcher; Kenneth L. Knittel

    2004-06-08

    The work performed on this program was to develop wear resistant, tough FM composite materials with efforts focused on WC-Co based FM systems. The materials were developed for use in mining industry wear applications. Components of interest were drill bit inserts for drilling blast holes. Other component applications investigated included wear plates for a variety of equipment such as pit shovels, wear surfaces for conveyors, milling media for ball milling operations, hydrocyclone cones, grader blades and dozer teeth. Cross-cutting technologies investigated included hot metal extrusion dies, drill bits for circuit board fabrication, cutting tools for cast iron and aluminum machining. An important part of the work was identification of the standard materials used in drilling applications. A materials trade study to determine those metals and ceramics used for mining applications provided guidance for the most important materials to be investigated. WC-Co and diamond combinations were shown to have the most desirable properties. Other considerations such as fabrication technique and the ability to consolidate shifted the focus away from diamond materials and toward WC-Co. Cooperating partners such as Kennametal and Kyocera assisted with supplies, evaluations of material systems, fabricated parts and suggestions for cross-cutting technology applications for FM architectures. Kennametal provided the raw materials (WC-Co and Al-TiCN powders) for the extent of the material evaluations. Kyocera shared their research into various FM systems and provided laboratory testing of fabricated materials. Field testing provided by partners Superior Rock Bit and Brady Mining and Construction provided insight into the performance of the fabricated materials under actual operational conditions. Additional field testing of cross-cutting technology, the extrusion of hot metals, at Extruded Metals showed the potential for additional market development.

  15. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2006-01-01

    In 2005, estimated world production of natural and synthetic industrial diamond was 630 million carats. Natural industrial diamond deposits were found in more than 35 countries. Synthetic industrial diamond is produced in at least 15 countries. More than 81% of the combined natural and synthetic global output was produced in Ireland, Japan, Russia, South Africa and the United States.

  16. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2011-01-01

    Estimated world production of natural and synthetic industrial diamond was about 4.44 billion carats in 2010. Natural industrial diamond deposits have been found in more than 35 countries, and synthetic industrial diamond is produced in at least 15 countries.

  17. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2013-01-01

    Estimated 2012 world production of natural and synthetic industrial diamond was about 4.45 billion carats. During 2012, natural industrial diamonds were produced in at least 20 countries, and synthetic industrial diamond was produced in at least 12 countries. About 99 percent of the combined natural and synthetic global output was produced in Belarus, China, Ireland, Japan, Russia, South Africa and the United States. During 2012, China was the world’s leading producer of synthetic industrial diamond followed by the United States and Russia. In 2012, the two U.S. synthetic producers, one in Pennsylvania and the other in Ohio, had an estimated output of 103 million carats, valued at about $70.6 million. This was an estimated 43.7 million carats of synthetic diamond bort, grit, and dust and powder with a value of $14.5 million combined with an estimated 59.7 million carats of synthetic diamond stone with a value of $56.1 million. Also in 2012, nine U.S. firms manufactured polycrystalline diamond (PCD) from synthetic diamond grit and powder. The United States government does not collect or maintain data for either domestic PCD producers or domestic chemical vapor deposition (CVD) diamond producers for quantity or value of annual production. Current trade and consumption quantity data are not available for PCD or for CVD diamond. For these reasons, PCD and CVD diamond are not included in the industrial diamond quantitative data reported here.

  18. FPGA-Based Fused Smart-Sensor for Tool-Wear Area Quantitative Estimation in CNC Machine Inserts

    PubMed Central

    Trejo-Hernandez, Miguel; Osornio-Rios, Roque Alfredo; de Jesus Romero-Troncoso, Rene; Rodriguez-Donate, Carlos; Dominguez-Gonzalez, Aurelio; Herrera-Ruiz, Gilberto

    2010-01-01

    Manufacturing processes are of great relevance nowadays, when there is a constant claim for better productivity with high quality at low cost. The contribution of this work is the development of a fused smart-sensor, based on FPGA to improve the online quantitative estimation of flank-wear area in CNC machine inserts from the information provided by two primary sensors: the monitoring current output of a servoamplifier, and a 3-axis accelerometer. Results from experimentation show that the fusion of both parameters makes it possible to obtain three times better accuracy when compared with the accuracy obtained from current and vibration signals, individually used. PMID:22319304

  19. Lubrication by Diamond and Diamondlike Carbon Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1997-01-01

    Regardless of environment (ultrahigh vacuum, humid air, dry nitrogen, or water), ion-beam-deposited diamondlike carbon (DLC) and nitrogen-ion-implanted, chemical-vapor-deposited (CVD) diamond films had low steady-state coefficients of friction (less than 0.1) and low wear rates (less than or equal to 10(exp -6)cu mm/N(dot)m). These films can be used as effective wear-resistant, self-lubricating coatings regardless of environment. On the other hand, as-deposited, fine-grain CVD diamond films; polished, coarse-grain CVD diamond films; and polished and then fluorinated, coarse-grain CVD diamond films can be used as effective wear-resistant, self-lubricating coatings in humid air, in dry nitrogen, and in water, but they had a high coefficient of friction and a high wear rate in ultrahigh vacuum. The polished, coarse-grain CVD diamond film revealed an extremely low wear rate, far less than 10(exp 10) cu mm/N(dot)m, in water.

  20. Spacetime diamonds

    NASA Astrophysics Data System (ADS)

    Su, Daiqin; Ralph, T. C.

    2016-02-01

    We show that the particle-number distribution of diamond modes, modes that are localized in a finite spacetime region, are thermal for the Minkowski vacuum state of a massless scalar field, an analogue to the Unruh effect. The temperature of the diamond is inversely proportional to its size. An inertial observer can detect this thermal radiation by coupling to the diamond modes using an appropriate energy-scaled detector. We further investigate the correlations between various diamonds and find that entanglement between adjacent diamonds dominates.

  1. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. A review of the state of the global industrial diamond industry in 1999 is presented. World consumption of industrial diamond has increased annually in recent years, with an estimated 500 million carats valued between $650 million and $800 million consumed in 1999. In 1999, the U.S. was the world's largest market for industrial diamond and was also one of the world's main producers; the others were Ireland, Russia, and South Africa. Uses of industrial diamonds are discussed, and prices of natural and synthetic industrial diamond are reported.

  2. Diamond film deposition on WC-Co and steel substrates with a CrN interlayer for tribological applications

    NASA Astrophysics Data System (ADS)

    Chandran, Maneesh; Hoffman, Alon

    2016-06-01

    The most renowned property of diamond is its exceptional hardness. By depositing diamond films on tungsten carbide (WC-Co) and steel substrates, the hardness of diamond can be combined with the toughness of these materials, resulting in an excellent wear resistance material for tribological applications. However, poor adhesion of diamond coating on these substrates leads to a lesser lifetime for the diamond coated tools than expected. The prime reasons for the lack of proper adhesion are the preferential formation of graphitic layer at the interface due to the catalytic activities of cobalt/iron and the interfacial residual stresses due to the mismatch in thermal expansion coefficients of diamond (1.5  ×  10-6 K-1) and WC-Co (5.2  ×  10-6 K-1) or steel (12  ×  10-6 K-1). In this review, we discuss the possibility of using a Cr-N interlayer as a diffusion barrier to prevent the catalytic activities of cobalt/iron and also to relax the interfacial residual stresses to some extent to enhance the adhesion of diamond coatings on these substrates. An overview of the most pertinent results of the last two decades, including the recent progress is introduced. We describe in detail how the Cr-N interlayer with the desired properties is fabricated. We give a concise overview of diamond deposition process, including the methods to vary the grain size from microcrystalline to nanocrystalline, which are suitable for some tribological applications. We describe in detail on surface and interface analysis, residual stress measurements, assessment adhesion strength and tribological performance of diamond coated WC-Co and steel substrates using various characterization techniques. We conclude by highlighting the current progress and future perspectives of diamond coatings on these substrates for tribological applications.

  3. A procedure for diamond turning KDP crystals

    SciTech Connect

    Montesanti, R.C.; Thompson, S.L.

    1995-07-07

    A procedure and the equipment necessary for single-point diamond flycutting (loosely referred to as diamond turning) potassium di-hydrogen phosphate (KDP) crystals are described. It is based on current KDP diamond turning activities at the Lawrence Livermore National Laboratory (LLNL), drawing upon knowledge from the Nova crystal finishing development during the 1980`s and incorporating refinements from our efforts during 1995. In addition to describing a step-by-step process for diamond turning KDP, specific discussions are included on the necessary diamond tool geometry and edge sharpness, cutting fluid, and crystal preparation, handling, cleaning, and inspection. The authors presuppose that the reader is already familiar with diamond turning practices.

  4. FIBROUS MONOLITH WEAR RESISTANT COMPONENTS FOR THE MINING INDUSTRY

    SciTech Connect

    Mark J. Rigali

    2001-10-01

    Published mechanical and thermal properties data on a variety of materials was gathered, with focus on materials that have potential with respect to developing wear resistant and damage tolerant composite for mining industry applications. Preliminary core materials of interest include but are not limited to: Diamond, Tungsten Carbide and Cemented Tungsten Carbides, Carbides of Boron, Silicon, Titanium and Aluminum, Diboride of Titanium and Aluminum, Nitrides of Aluminum, Silicon, Titanium, and Boron, Aluminum Oxide, Tungsten, Titanium, Iron, Cobalt and Metal Alloys. Preliminary boundary materials of interest include but are not limited to: W metal, WC-Co, W-Co, WFeNi, and Mo metal and alloys. Several FM test coupons were fabricated with various compositions using the above listed materials. These coupons were consolidated to varying degrees by uniaxial hot pressing, then cut and ground to expose the FM cell structure. One promising system, WC-Co core and WFeNi boundary, was consolidated to 97% of theoretical density, and demonstrates excellent hardness. Data on standard mechanical tests was gathered, and tests will begin on the consolidated test coupons during the upcoming reporting period. The program statements of work for ACR Inc. and its subcontractors, as well as the final contract negotiations, were finalized during the current reporting period. The program start date was February 22nd, 2001. In addition to the current subcontractors, Kennametal Inc., a major manufacturer of cutting tools and wear resistant tooling for the mining industry, expressed considerable interest in ACR's Fibrous Monolith composites for both machine and mining applications. At the request of Kennametal, ARC Inc fabricated and delivered several Fibrous Monolith coupons and components for testing and evaluation in the mining and machine tool applications. Additional samples of Diamond/Tungsten Carbide-6%Cobalt Fibrous Monolith were fabricated and delivered for testing Kennametal's Rapid

  5. Physical and Tribological Characteristics of Ion-Implanted Diamond Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Heidger, S.; Korenyi-Both, A. L.; Jayne, D. T.; Herrera-Fierro, P.; Shogrin, B.; Wilbur, P. J.; Wu, R. L. C.; Garscadden, A.; Barnes, P. N.

    1994-01-01

    Unidirectional sliding friction experiments were conducted with a natural, polished diamond pin in contact with both as-deposited and carbon-ion-implanted diamond films in ultrahigh vacuum. Diamond films were deposited on silicon, silicon carbide, and silicon nitride by microwave-plasma-assisted chemical vapor deposition. The as-deposited diamond films were impacted with carbon ions at an accelerating energy of 60 keV and a current density of 50 micron A/cm(exp 2) for approximately 6 min, resulting in a dose of 1.2 x 10(exp 17) carbon ions/cm(exp 2). The results indicate that the carbon ion implantation produced a thin surface layer of amorphous, nondiamond carbon. The nondiamond carbon greatly decreased both friction and wear of the diamond films. The coefficients of friction for the carbon-ion-implanted, fine-grain diamond films were less than 0.1, factors of 20 to 30 lower than those for the as-deposited, fine-grain diamond films. The coefficients of friction for the carbon-ion-implanted, coarse-grain diamond films were approximately 0.35, a factor of five lower than those for the as-deposited, coarse-grain diamond films. The wear rates for the carbon-ion-implanted, diamond films were on the order of 10(exp -6) mm(exp 3)/Nm, factors of 30 to 80 lower than that for the as-deposited diamond films, regardless of grain size. The friction of the carbon-ion-implanted diamond films was greatly reduced because the amorphous, nondiamond carbon, which had a low shear strength, was restricted to the surface layers (less than 0.1 micron thick) and because the underlying diamond materials retained their high hardness. In conclusion, the carbon-ion-implanted, fine-grain diamond films can be used effectively as wear resistant, self-lubricating coatings for ceramics, such as silicon nitride and silicon carbide, in ultrahigh vacuum.

  6. Picosecond laser fabrication of micro cutting tool geometries on polycrystalline diamond composites using a high-numerical aperture micro scanning system

    NASA Astrophysics Data System (ADS)

    Eberle, Gregory; Dold, Claus; Wegener, Konrad

    2015-03-01

    The generation of microsized components found in LEDs, watches, molds as well as other types of micromechanics and microelectronics require a corresponding micro cutting tool in order to be manufactured, typically by milling or turning. Micro cutting tools are made of cemented tungsten carbide and are conventionally fabricated either by electrical discharge machining (EDM) or by grinding. An alternative method is proposed through a laser-based solution operating in the picosecond pulse duration whereby the beam is deflected using a modified galvanometer-driven micro scanning system exhibiting a high numerical aperture. A micro cutting tool material which cannot be easily processed using conventional methods is investigated, which is a fine grain polycrystalline diamond composite (PCD). The generation of various micro cutting tool relevant geometries, such as chip breakers and cutting edges, are demonstrated. The generated geometries are subsequently evaluated using scanning electron microscopy (SEM) and quality is measured in terms of surface roughness and cutting edge sharpness. Additionally, two processing strategies in which the laser beam processes tangentially and orthogonally are compared in terms of quality.

  7. Effect of cryogenic treatment on microstructure, mechanical and wear behaviors of AISI H13 hot work tool steel

    NASA Astrophysics Data System (ADS)

    Koneshlou, Mahdi; Meshinchi Asl, Kaveh; Khomamizadeh, Farzad

    2011-01-01

    This paper focuses on the effects of low temperature (subzero) treatments on microstructure and mechanical properties of H13 hot work tool steel. Cryogenic treatment at -72 °C and deep cryogenic treatment at -196 °C were applied and it was found that by applying the subzero treatments, the retained austenite was transformed to martensite. As the temperature was decreased more retained austenite was transformed to martensite and it also led to smaller and more uniform martensite laths distributed in the microstructure. The deep cryogenic treatment also resulted in precipitation of more uniform and very fine carbide particles. The microstructural modification resulted in a significant improvement on the mechanical properties of the H13 tool steel.

  8. Investigation of wear phenomena by microscopy

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1982-01-01

    The various wear mechanisms involved in the loss of material from metallic and nonmetallic surfaces are discussed. The results presented indicate how various microscopy techniques used in conjunction with other analytical tools can assist in the elucidation of a wear mechanism. Without question, microscopy is the single most important tool for the study of the wear of surfaces, to assess and address inherent mechanisms of the material removal process.

  9. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2007-01-01

    World production of natural and synthetic industrial diamond was about 648 million carats in 2006, with 79 percent of the production coming from Ireland, Japan, Russia, South Africa, and the U.S. U.S. consumption was was an estimated 602 million carats, imports were over 391 million carats, and exports were about 83 million carats. About 87 percent of the industrial diamonds market uses synthetic diamonds, which are expected to become less expensive as technology improves and competition from low-cost producers increases.

  10. Dynamic SEM wear studies of tungsten carbide cermets

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined. Etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the WC and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation. The wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  11. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2004-01-01

    Part of the 2003 industrial minerals review. Supply and demand data for industrial diamond are provided. Topics discussed are consumption, prices, imports and exports, government stockpiles, and the outlook for 2004.

  12. Diamond nanophotonics

    PubMed Central

    Beha, Katja; Wolfer, Marco; Becker, Merle C; Siyushev, Petr; Jamali, Mohammad; Batalov, Anton; Hinz, Christopher; Hees, Jakob; Kirste, Lutz; Obloh, Harald; Gheeraert, Etienne; Naydenov, Boris; Jakobi, Ingmar; Dolde, Florian; Pezzagna, Sébastien; Twittchen, Daniel; Markham, Matthew; Dregely, Daniel; Giessen, Harald; Meijer, Jan; Jelezko, Fedor; Nebel, Christoph E; Bratschitsch, Rudolf; Leitenstorfer, Alfred; Wrachtrup, Jörg

    2012-01-01

    Summary We demonstrate the coupling of single color centers in diamond to plasmonic and dielectric photonic structures to realize novel nanophotonic devices. Nanometer spatial control in the creation of single color centers in diamond is achieved by implantation of nitrogen atoms through high-aspect-ratio channels in a mica mask. Enhanced broadband single-photon emission is demonstrated by coupling nitrogen–vacancy centers to plasmonic resonators, such as metallic nanoantennas. Improved photon-collection efficiency and directed emission is demonstrated by solid immersion lenses and micropillar cavities. Thereafter, the coupling of diamond nanocrystals to the guided modes of micropillar resonators is discussed along with experimental results. Finally, we present a gas-phase-doping approach to incorporate color centers based on nickel and tungsten, in situ into diamond using microwave-plasma-enhanced chemical vapor deposition. The fabrication of silicon–vacancy centers in nanodiamonds by microwave-plasma-enhanced chemical vapor deposition is discussed in addition. PMID:23365803

  13. Preliminary evaluation of the relationship of bit wear to cutting distance, forces, and dust using selected commercial and experimental coal- and rock-cutting tools. Report of Investigations/1988

    SciTech Connect

    Plis, M.N.; Wingquist, C.F.; Roepke, W.W.

    1988-01-01

    The report describes the initial results of long-range research on bit life conducted by the Bureau of Mines. Three commercial bit designs--a round-nose radial, 60 deg conical, and 90 deg conical with tungsten carbide (WC) inserts--and five experimental bits were tested. Four of the experimental bits were radial designs using polycrystalline diamond compact (PDC) inserts. The fifth was a 90 deg conical with an oversize WC insert. Bits were worn on a high-silica sandstone typical of coal mine roofs. The bits were mounted on a 34-in-diam drum section that provided a bit speed of 565 ft/min. Cutting forces were measured on a modified vertical slotter using a three-axis force dynamometer and recorded on an FM magnetic tape recorder. Changes in cutting forces, bit weight, and airborne dust due to gradual abrasive wear and catastrophic insert failure are presented. Tabulated and graphed data, photographs of the progression of bit wear, and selected qualitative visual and auditory observations of the bits taken throughout the experiment are found in the appendixes.

  14. Diamond fiber field emitters

    DOEpatents

    Blanchet-Fincher, Graciela B.; Coates, Don M.; Devlin, David J.; Eaton, David F.; Silzars, Aris K.; Valone, Steven M.

    1996-01-01

    A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.

  15. Wear study under plastic deformation conditions

    NASA Astrophysics Data System (ADS)

    Shukla, B. M.; Singhal, S.; Singh, D. V.

    1994-03-01

    Lubrication in metalworking processes is characterized by plastic deformation conditions resulting in generation of a large amount of virgin surface and of heat of deformation. The study of wear under these conditions is important from the point of view of product quality and tool/die wear. A laboratory study of wear under simulated plastic deformation conditions using pairs of mild steel and EN31 discs on an Amsler friction and wear testing machine was carried out. The worn surfaces and wear particles were examined by scanning electron microscopy. It was observed that wear with a mineral oil was greater than that with a vegetable oil. This paper analyzes the phenomenon through an examination of the surfaces and the wear particles.

  16. Tribological properties of smooth diamond films

    NASA Astrophysics Data System (ADS)

    Pimenov, S. M.; Smolin, A. A.; Obraztsova, E. D.; Konov, V. I.; Bögli, U.; Blatter, A.; Loubnin, E. N.; Maillat, M.; Leijala, A.; Burger, J.; Hintermann, H. E.

    1996-02-01

    The friction and wear properties of smooth diamond coatings sliding against a monocrystalline ruby ball were studied using a pin-on-disk tribometer. The smooth diamond film surface was prepared either by (i) deposition of ultrathin nanocrystalline films in the thickness range from 0.2 to 2 μm or by (ii) postgrowth polishing. Excimer laser surface ablation, microwave plasma etching and mechanical lapping with diamond grit were used for postgrowth polishing. A correlation of film surface properties examined with different techniques (atomic force microscopy, Auger electron spectroscopy, Raman spectroscopy, stylus profilometry) and the tribological properties of the diamond films tested was established. The influence of laser-induced surface graphitization on the friction coefficient of laser-polished films was investigated.

  17. 'Diamond' in 3-D

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  18. Quantifying the effects of tool and workpiece surface evolution during microgrinding of optical glasses

    NASA Astrophysics Data System (ADS)

    Takahashi, Toshio; Funkenbusch, Paul D.; Ruckman, Jeffrey L.

    1999-11-01

    CNC grinding technology is increasingly used in the manufacture of precision optical components. Grinding performance is strongly influenced by the interaction of the tool and workpiece surfaces on a microscale, which in turn is influenced by the structure (topography) of the two surfaces. Unfortunately, for tool surfaces in particular, relatively little quantitative information has been available on the nature of the surfaces generated during actual grinding operations. However with the availability of advanced metrology techniques, such as optical profilometry and atomic force microscopy, it is now possible to produce detailed three-dimensional images of tool surfaces and from them to extract detailed quantitative information about the surface and its evolution. In this paper we discuss the use of optical profilometry to quantitatively characterize the surface microstructure (topography) of composite diamond tools during grinding of optical glasses. As an alternative to measuring individual diamond profiles, both the size and shape of the active diamonds on the tool surface may be evaluated by examination of the overall bearing ratio of the surface. This is quicker and has the advantage of avoiding potential bias in the selection of diamonds to be measured. Use of a micro- marker technique to precisely measure bond wear rate from a series of surface images using a micro-marker technique is also demonstrated. Grinding performance is dependent on the process conditions, but is also found to be correlated with the tool's surface structure. Moreover since the tool surface evolves during grinding, a complex relationship between the process and performance is produced. Bond wear is found to play an important role in maintaining grinding performance. Process conditions which produce a steady bond wear rate aid in establishing a quasi-equilibrium state ('self-sharpening') under which grinding performance can be maintained indefinitely.

  19. Structures and Mechanical Properties of Natural and Synthetic Diamonds

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1998-01-01

    A revolution in the diamond technology is in progress, as the low-pressure process becomes an industrial reality. It will soon be possible to take advantage of the demanding properties of diamond to develop a myriad of new applications, particularly for self-lubricating, wear-resistant, and superhard coatings. The production of large diamond films or sheets at low cost, a distinct possibility in the not-too-distant future, may drastically change tribology technology, particularly regarding solid lubricants and lubricating materials and systems. This paper reviews the structures and properties of natural and synthetic diamonds to gain a better understanding of the tribological properties of diamond and related materials. Atomic and crystal structure, impurities, mechanical properties, and indentation hardness of diamond are described.

  20. Adhesion and wear resistance of materials

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1986-01-01

    Recent studies into the nature of bonding at the interface between two solids in contact or a solid and deposited film have provided a better understanding of those properties important to the adhesive wear resistance of materials. Analytical and experimental progress are reviewed. For simple metal systems the adhesive bond forces are related to electronic wave function overlap. With metals in contact with nonmetals, molecular-orbital energy, and density of states, respectively can provide insight into adhesion and wear. Experimental results are presented which correlate adhesive forces measured between solids and the electronic surface structures. Orientation, surface reconstruction, surface segregation, adsorption are all shown to influence adhesive interfacial strength. The interrelationship between adhesion and the wear of the various materials as well as the life of coatings applied to substrates are discussed. Metallic systems addressed include simple metals and alloys and these materials in contact with themselves, both oxide and nonoxide ceramics, diamond, polymers, and inorganic coating compounds, h as diamondlike carbon.

  1. Nanocrystalline diamond for medicine

    NASA Astrophysics Data System (ADS)

    Mitura, Stanislaw

    1997-06-01

    The unique properties of thin amorphous diamond layers make them perspective candidates for producing advanced micro- electronic devices, coatings for cutting tools and optics. Moreover, due to the highest bicompatibility of carbon resulting from the presence of this element in human body, it appears to be a potential biomaterial. Until present the amorphous diamond has found industrial applications in some areas. One of the applications of the carbon layers are coatings for medical implants. The studies of carbon films as coatings for implants in surgery were aimed on the investigations of biological resistance of implants, histopathological investigations on laboratory animals, tests of corrosion resistance, measurements of mechanical properties and a breakdown test in Tyrod solution. The current state of published work in the subject is reviewed in the paper together with a discussion concerning classification of this material.

  2. Diagnostic Techniques Used to Study Chemical-Vapor-Deposited Diamond Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2000-01-01

    The advantages and utility of chemical-vapor-deposited (CVD) diamond as an industrial ceramic can only be realized if the price and quality are right. Until recently, this technology was of interest only to the academic and basic research community. However, interest has grown because of advances made by leading CVD diamond suppliers: 1) Reduction of the cost of CVD polycrystalline diamond deposition below $5/carat ($8/sq cm); 2) Installation of production capacity; 3) Epitaxial growth of CVD single-crystal diamond. Thus, CVD diamond applications and business are an industrial reality. At present, CVD diamond is produced in the form of coatings or wafers. CVD diamond film technology offers a broader technological potential than do natural and high-pressure synthetic diamonds because size, geometry, and eventually cost will not be as limiting. Now that they are cost effective, diamond coatings - with their extreme properties - can be used in a variety of applications. Diamond coatings can improve many of the surface properties of engineering substrate materials, including erosion, corrosion, and wear resistance. Examples of actual and potential applications, from microelectromechanical systems to the wear parts of diamond coatings and related superhard coatings are described. For example, diamond coatings can be used as a chemical and mechanical barrier for the space shuttles check valves, particularly on the guide pins and seat assemblies.

  3. Tribological properties of amorphous alloys and the role of surfaces in abrasive wear of materials

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The research approach undertaken by the authors relative to the subject, and examples of results from the authors are reviewed. The studies include programs in adhesion, friction, and various wear mechanisms (adhesive and abrasive wear). The materials which have been studied include such ceramic and metallic materials as silicon carbide, ferrites, diamond, and amorphous alloys.

  4. Abrasive wear behavior of heat-treated ABC-silicon carbide

    SciTech Connect

    Zhang, Xiao Feng; Lee, Gun Y.; Chen, Da; Ritchie, Robert O.; De Jonghe, Lutgard C.

    2002-06-17

    Hot-pressed silicon carbide, containing aluminum, boron, and carbon additives (ABC-SiC), was subjected to three-body and two-body wear testing using diamond abrasives over a range of sizes. In general, the wear resistance of ABC-SiC, with suitable heat treatment, was superior to that of commercial SiC.

  5. A model for predicting wear rates in tooth enamel.

    PubMed

    Borrero-Lopez, Oscar; Pajares, Antonia; Constantino, Paul J; Lawn, Brian R

    2014-09-01

    It is hypothesized that wear of enamel is sensitive to the presence of sharp particulates in oral fluids and masticated foods. To this end, a generic model for predicting wear rates in brittle materials is developed, with specific application to tooth enamel. Wear is assumed to result from an accumulation of elastic-plastic micro-asperity events. Integration over all such events leads to a wear rate relation analogous to Archard׳s law, but with allowance for variation in asperity angle and compliance. The coefficient K in this relation quantifies the wear severity, with an arbitrary distinction between 'mild' wear (low K) and 'severe' wear (high K). Data from the literature and in-house wear-test experiments on enamel specimens in lubricant media (water, oil) with and without sharp third-body particulates (silica, diamond) are used to validate the model. Measured wear rates can vary over several orders of magnitude, depending on contact asperity conditions, accounting for the occurrence of severe enamel removal in some human patients (bruxing). Expressions for the depth removal rate and number of cycles to wear down occlusal enamel in the low-crowned tooth forms of some mammals are derived, with tooth size and enamel thickness as key variables. The role of 'hard' versus 'soft' food diets in determining evolutionary paths in different hominin species is briefly considered. A feature of the model is that it does not require recourse to specific material removal mechanisms, although processes involving microplastic extrusion and microcrack coalescence are indicated.

  6. Nanostructured diamond coatings for orthopaedic applications

    PubMed Central

    CATLEDGE, S.A.; THOMAS, V.; VOHRA, Y.K.

    2013-01-01

    With increasing numbers of orthopaedic devices being implanted, greater emphasis is being placed on ceramic coating technology to reduce friction and wear in mating total joint replacement components, in order to improve implant function and increase device lifespan. In this chapter, we consider ultra-hard carbon coatings, with emphasis on nanostructured diamond, as alternative bearing surfaces for metallic components. Such coatings have great potential for use in biomedical implants as a result of their extreme hardness, wear resistance, low friction and biocompatibility. These ultra-hard carbon coatings can be deposited by several techniques resulting in a wide variety of structures and properties. PMID:25285213

  7. Diamond knife.

    PubMed

    Rowsey, J J; Balyeat, H D; Yeisley, K P

    1982-04-01

    We present a new diamond knife which allows for reasonably precise incisions in cornea or sclera. The knife may be ultrasonically cleaned and is sharper than any metal knife whose edge we have examined to date by scanning electron microscopy. The edge is approximately 0.1 micron in width, compared to 1-5 micron width edges of most metal knives. We feel that this prototype will allow investigators to recommend special modifications to the manufacturer of their own choice. PMID:6285246

  8. Diamond Tours

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On April 24, a group traveling with Diamond Tours visited StenniSphere, the visitor center at NASA John C. Stennis Space Center in South Mississippi. The trip marked Diamond Tours' return to StenniSphere since Hurricane Katrina struck the Gulf Coast on Aug. 29, 2005. About 25 business professionals from Georgia enjoyed the day's tour of America's largest rocket engine test complex, along with the many displays and exhibits at the museum. Before Hurricane Katrina, the nationwide company brought more than 1,000 visitors to StenniSphere each month. That contributed to more than 100,000 visitors from around the world touring the space center each year. In past years StenniSphere's visitor relations specialists booked Diamond Tours two or three times a week, averaging 40 to 50 people per visit. SSC was established in the 1960s to test the huge engines for the Saturn V moon rockets. Now 40 years later, the center tests every main engine for the space shuttle. SSC will soon begin testing the rocket engines that will power spacecraft carrying Americans back to the moon and on to Mars. For more information or to book a tour, visit http://www.nasa.gov/centers/stennis/home/index.html and click on the StenniSphere logo; or call 800-237-1821 or 228-688-2370.

  9. Nanocrystalline diamond coatings for mechanical seals applications.

    PubMed

    Santos, J A; Neto, V F; Ruch, D; Grácio, J

    2012-08-01

    A mechanical seal is a type of seal used in rotating equipment, such as pumps and compressors. It consists of a mechanism that assists the connection of the rotating shaft to the housings of the equipments, preventing leakage or avoiding contamination. A common cause of failure of these devices is end face wear out, thus the use of a hard, smooth and wear resistant coating such as nanocrystalline diamond would be of great importance to improve their working performance and increase their lifetime. In this paper, different diamond coatings were deposited by the HFCVD process, using different deposition conditions. Additionally, the as-grown films were characterized for, quality, morphology and microstructure using scanning electron microscopy (SEM) and Raman spectroscopy. The topography and the roughness of the films were characterized by atomic force microscopy (AFM). PMID:22962831

  10. Nanotwinned diamond with unprecedented hardness and stability.

    PubMed

    Huang, Quan; Yu, Dongli; Xu, Bo; Hu, Wentao; Ma, Yanming; Wang, Yanbin; Zhao, Zhisheng; Wen, Bin; He, Julong; Liu, Zhongyuan; Tian, Yongjun

    2014-06-12

    Although diamond is the hardest material for cutting tools, poor thermal stability has limited its applications, especially at high temperatures. Simultaneous improvement of the hardness and thermal stability of diamond has long been desirable. According to the Hall-Petch effect, the hardness of diamond can be enhanced by nanostructuring (by means of nanograined and nanotwinned microstructures), as shown in previous studies. However, for well-sintered nanograined diamonds, the grain sizes are technically limited to 10-30 nm (ref. 3), with degraded thermal stability compared with that of natural diamond. Recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to ∼3.8 nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability. At present, nanotwinned diamond (nt-diamond) has not been fabricated successfully through direct conversions of various carbon precursors (such as graphite, amorphous carbon, glassy carbon and C60). Here we report the direct synthesis of nt-diamond with an average twin thickness of ∼5 nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond. The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to ∼200 GPa and an in-air oxidization temperature more than 200 °C higher than that of natural diamond. The creation of nanotwinned microstructures offers a general pathway for manufacturing new advanced carbon-based materials with exceptional thermal stability and mechanical properties.

  11. Nanotwinned diamond with unprecedented hardness and stability

    NASA Astrophysics Data System (ADS)

    Huang, Quan; Yu, Dongli; Xu, Bo; Hu, Wentao; Ma, Yanming; Wang, Yanbin; Zhao, Zhisheng; Wen, Bin; He, Julong; Liu, Zhongyuan; Tian, Yongjun

    2014-06-01

    Although diamond is the hardest material for cutting tools, poor thermal stability has limited its applications, especially at high temperatures. Simultaneous improvement of the hardness and thermal stability of diamond has long been desirable. According to the Hall-Petch effect, the hardness of diamond can be enhanced by nanostructuring (by means of nanograined and nanotwinned microstructures), as shown in previous studies. However, for well-sintered nanograined diamonds, the grain sizes are technically limited to 10-30 nm (ref. 3), with degraded thermal stability compared with that of natural diamond. Recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to ~3.8 nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability. At present, nanotwinned diamond (nt-diamond) has not been fabricated successfully through direct conversions of various carbon precursors (such as graphite, amorphous carbon, glassy carbon and C60). Here we report the direct synthesis of nt-diamond with an average twin thickness of ~5 nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond. The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to ~200 GPa and an in-air oxidization temperature more than 200 °C higher than that of natural diamond. The creation of nanotwinned microstructures offers a general pathway for manufacturing new advanced carbon-based materials with exceptional thermal stability and mechanical properties.

  12. Understanding wear in dentistry.

    PubMed

    Mair, L H

    1999-01-01

    Tooth wear is an increasing problem in dentistry. Traditionally, it has been divided into three categories: abrasion, attrition, and erosion. However, most clinical cases of tooth wear involve more than one of these processes. It is often easier to make a diagnosis by looking for the signs of the fundamental wear processes rather than trying to categorize the individual case. Wear can be caused by direct surface-to-surface wear, an intervening slurry, or a corrosive environment. Wear occurs during mastication, but also at other times, often at night. Although it may be possible to institute a preventive regimen, this will not always help the patient if his or her prime concern is esthetics. The same processes that cause tooth wear will cause wear to restorative materials. To diagnose and prevent wear, its processes must be understood.

  13. Machinability of lithium disilicate glass ceramic in in vitro dental diamond bur adjusting process.

    PubMed

    Song, Xiao-Fei; Ren, Hai-Tao; Yin, Ling

    2016-01-01

    Esthetic high-strength lithium disilicate glass ceramics (LDGC) are used for monolithic crowns and bridges produced in dental CAD/CAM and oral adjusting processes, which machinability affects the restorative quality. A machinability study has been made in the simulated oral clinical machining of LDGC with a dental handpiece and diamond burs, regarding the diamond tool wear and chip control, machining forces and energy, surface finish and integrity. Machining forces, speeds and energy in in vitro dental adjusting of LDGC were measured by a high-speed data acquisition and force sensor system. Machined LDGC surfaces were assessed using three-dimensional non-contact chromatic confocal optical profilometry and scanning electron microscopy (SEM). Diamond bur morphology and LDGC chip shapes were also examined using SEM. Minimum tool wear but significant LDGC chip accumulations were found. Machining forces and energy significantly depended on machining conditions (p<0.05) and were significantly higher than other glass ceramics (p<0.05). Machining speeds dropped more rapidly with increased removal rates than other glass ceramics (p<0.05). Two material machinability indices associated with the hardness, Young's modulus and fracture toughness were derived based on the normal force-removal rate relations, which ranked LDGC the most difficult to machine among glass ceramics. Surface roughness for machined LDGC was comparable for other glass ceramics. The removal mechanisms of LDGC were dominated by penetration-induced brittle fracture and shear-induced plastic deformation. Unlike most other glass ceramics, distinct intergranular and transgranular fractures of lithium disilicate crystals were found in LDGC. This research provides the fundamental data for dental clinicians on the machinability of LDGC in intraoral adjustments. PMID:26318569

  14. Machinability of lithium disilicate glass ceramic in in vitro dental diamond bur adjusting process.

    PubMed

    Song, Xiao-Fei; Ren, Hai-Tao; Yin, Ling

    2016-01-01

    Esthetic high-strength lithium disilicate glass ceramics (LDGC) are used for monolithic crowns and bridges produced in dental CAD/CAM and oral adjusting processes, which machinability affects the restorative quality. A machinability study has been made in the simulated oral clinical machining of LDGC with a dental handpiece and diamond burs, regarding the diamond tool wear and chip control, machining forces and energy, surface finish and integrity. Machining forces, speeds and energy in in vitro dental adjusting of LDGC were measured by a high-speed data acquisition and force sensor system. Machined LDGC surfaces were assessed using three-dimensional non-contact chromatic confocal optical profilometry and scanning electron microscopy (SEM). Diamond bur morphology and LDGC chip shapes were also examined using SEM. Minimum tool wear but significant LDGC chip accumulations were found. Machining forces and energy significantly depended on machining conditions (p<0.05) and were significantly higher than other glass ceramics (p<0.05). Machining speeds dropped more rapidly with increased removal rates than other glass ceramics (p<0.05). Two material machinability indices associated with the hardness, Young's modulus and fracture toughness were derived based on the normal force-removal rate relations, which ranked LDGC the most difficult to machine among glass ceramics. Surface roughness for machined LDGC was comparable for other glass ceramics. The removal mechanisms of LDGC were dominated by penetration-induced brittle fracture and shear-induced plastic deformation. Unlike most other glass ceramics, distinct intergranular and transgranular fractures of lithium disilicate crystals were found in LDGC. This research provides the fundamental data for dental clinicians on the machinability of LDGC in intraoral adjustments.

  15. Tribological and Adhesion Properties of CVD Diamond Films Grown on Steel with a Cr-N Interlayer

    NASA Astrophysics Data System (ADS)

    Laikhtman, A.; Rapoport, L.; Perfilyev, V.; Moshkovich, A.; Akhvlediani, R.; Hoffman, A.

    2009-07-01

    In the present work we investigate friction and adhesion properties of microcrystalline diamond films grown on steel substrates with a Cr-N interlayer prepared at 500° C and 800° C. Scratch tests were performed at indentation loads of 1-4 N and sliding velocity of 0.08 mm/s. The friction coefficient and wear loss were assessed. The diamond film structure and composition are analyzed using different microscopic and spectroscopic techniques. The effect of the diamond structure on adhesion of the deposited diamond films to the substrates, as well as the friction coefficient and wear were evaluated. Continuous, good crystalline quality diamond films with a similar phase content and surface morphology were obtained on both, high and low temperature nitridated substrates, provide similar tribological properties of films. Thus, the temperature of interlayer preparation does not affect the friction coefficient and the size of wear profiles. Substantially different results were obtained when evaluating the adhesion properties of diamond films to the steel substrate. It was found that the diamond film deposited on the Cr-N interlayer prepared at 800° C shows the best adhesion. The diamond film was stable without visible cracks around the wear track during all scratch tests with different indentation loads. Weak adhesion was observed for the diamond film grown on the Cr-N interlayer prepared at a lower temperature (500° C) for which cracking and delamination of the films took place at loads of 1 N-1.2 N.

  16. Vibrational Raman characterization of hard carbon and diamond films

    SciTech Connect

    Ager, J.W. III; Veirs, D.K.; Cho, Namhee; Rosenblatt, G.M. ); Marchon, B. )

    1991-01-01

    Amorphous hard carbon'' and microcrystalline diamond films are being investigated and characterized using high-sensitivity and spatial-profiling Raman spectroscopy. The hard carbon'' films have broad Raman spectra with no diamond line while higher quality diamond films show only a single sharp diamond line. Features in the Raman spectra of the amorphous hard carbon'' films correlate with the rates of specific types of wear. Changes in the relative intensity of the Raman band near 1570 cm{sup {minus}1} (G-band) compared to the band near 1360 cm{sup {minus}1} (D-band) are related to the rate of abrasive wear. Shifts in the frequency of the G-band are related to the rate of tribochemical wear. The results are consistent with a structural model of amorphous carbon films in which small (<20{Angstrom}) graphitic microcrystals comprised of sp{sup 2} bonded domains are cross-linked by sp{sup 3} carbon atoms. Profiles of Raman frequency and linewidth obtained from spatially resolved Raman spectroscopy across CVD-grown diamond thin films show that the Raman frequency and position are correlated in these films and that both change in regions of poorer film quality. 14 refs., 4 figs.

  17. The mechanical and strength properties of diamond.

    PubMed

    Field, J E

    2012-12-01

    Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of

  18. Diamond and diamond-like carbon films for advanced electronic applications

    SciTech Connect

    Siegal, M.P.; Friedmann, T.A.; Sullivan, J.P.

    1996-03-01

    Aim of this laboratory-directed research and development (LDRD) project was to develop diamond and/or diamond-like carbon (DLC) films for electronic applications. Quality of diamond and DLC films grown by chemical vapor deposition (CVD) is not adequate for electronic applications. Nucleation of diamond grains during growth typically results in coarse films that must be very thick in order to be physically continuous. DLC films grown by CVD are heavily hydrogenated and are stable to temperatures {le} 400{degrees}C. However, diamond and DLC`s exceptional electronic properties make them candidates for integration into a variety of microelectronic structures. This work studied new techniques for the growth of both materials. Template layers have been developed for the growth of CVD diamond films resulting in a significantly higher nucleation density on unscratched or unprepared Si surfaces. Hydrogen-free DLC with temperature stability {le} 800{degrees}C has been developed using energetic growth methods such as high-energy pulsed-laser deposition. Applications with the largest system impact include electron-emitting materials for flat-panel displays, dielectrics for interconnects, diffusion barriers, encapsulants, and nonvolatile memories, and tribological coatings that reduce wear and friction in integrated micro-electro-mechanical devices.

  19. Designing shallow donors in diamond

    NASA Astrophysics Data System (ADS)

    Moussa, Jonathan

    2015-03-01

    The production of n-type semiconducting diamond has been a long-standing experimental challenge. The first-principles simulation of shallow dopants in semiconductors has been a long-standing theoretical challenge. A desirable theoretical goal is to identify impurities that will act as shallow donors in diamond and assess their experimental viability. I will discuss this identification process for the LiN4 donor complex. It builds a scientific argument from several models and computational results in the absence of computational tools that are both trustworthy and computationally tractable for this task. I will compare the theoretical assessment of viability with recent experimental efforts to co-dope diamond with lithium and nitrogen. Finally, I discuss the computational tools needed to facilitate future work on this problem and some preliminary simulations of donors near diamond surfaces. Sandia National Laboratories is a multi-program lab managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  20. Characterization and measurement of polymer wear

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Aron, P. R.

    1984-01-01

    Analytical tools which characterize the polymer wear process are discussed. The devices discussed include: visual observation of polymer wear with SEM, the quantification with surface profilometry and ellipsometry, to study the chemistry with AES, XPS and SIMS, to establish interfacial polymer orientation and accordingly bonding with QUARTIR, polymer state with Raman spectroscopy and stresses that develop in polymer films using a X-ray double crystal camera technique.

  1. Amorphous Diamond MEMS and Sensors

    SciTech Connect

    SULLIVAN, JOHN P.; FRIEDMANN, THOMAS A.; ASHBY, CAROL I.; DE BOER, MAARTEN P.; SCHUBERT, W. KENT; SHUL, RANDY J.; HOHLFELDER, ROBERT J.; LAVAN, D.A.

    2002-06-01

    This report describes a new microsystems technology for the creation of microsensors and microelectromechanical systems (MEMS) using stress-free amorphous diamond (aD) films. Stress-free aD is a new material that has mechanical properties close to that of crystalline diamond, and the material is particularly promising for the development of high sensitivity microsensors and rugged and reliable MEMS. Some of the unique properties of aD include the ability to easily tailor film stress from compressive to slightly tensile, hardness and stiffness 80-90% that of crystalline diamond, very high wear resistance, a hydrophobic surface, extreme chemical inertness, chemical compatibility with silicon, controllable electrical conductivity from insulating to conducting, and biocompatibility. A variety of MEMS structures were fabricated from this material and evaluated. These structures included electrostatically-actuated comb drives, micro-tensile test structures, singly- and doubly-clamped beams, and friction and wear test structures. It was found that surface micromachined MEMS could be fabricated in this material easily and that the hydrophobic surface of the film enabled the release of structures without the need for special drying procedures or the use of applied hydrophobic coatings. Measurements using these structures revealed that aD has a Young's modulus of {approx}650 GPa, a tensile fracture strength of 8 GPa, and a fracture toughness of 8 MPa{center_dot}m {sup 1/2}. These results suggest that this material may be suitable in applications where stiction or wear is an issue. Flexural plate wave (FPW) microsensors were also fabricated from aD. These devices use membranes of aD as thin as {approx}100 nm. The performance of the aD FPW sensors was evaluated for the detection of volatile organic compounds using ethyl cellulose as the sensor coating. For comparable membrane thicknesses, the aD sensors showed better performance than silicon nitride based sensors. Greater than

  2. Tribological properties of nanocrystalline diamond films

    SciTech Connect

    Erdemir, A.; Fenske, G. R.; Kraus, A. R.; Gruen, D. M.; McCauley, T.; Csencsits, R. T.

    2000-01-26

    In this paper, the authors present the friction and wear properties of nanocrystalline diamond (NCD) films grown in A-fullerene (C{sub 60}) and Ar-CH{sub 4} microwave plasmas. Specifically, they address the fundamental tribological issues posed by these films during sliding against Si{sub 3}N{sub 4} counterfaces in ambient air and inert gases. Grain sizes of the films grown by the new method are very small (10--30 nm) and are much smoother (20-40 nm, root mean square) than those of films grown by the conventional H{sub 2}-CH{sub 4} microwave-assisted chemical-vapor-deposition (CVD) process. Transmission electron microscopy (TEM) revealed that the grain boundaries of these films are very sharp and free of nondiamond phases. The microcrystalline diamond (MCD) films grown by most conventional methods consist of large grains and a rough surface finish, which can cause severe abrasion during sliding against other materials. The friction coefficients of films grown by the new method (i.e., in Ar-C{sub 60} and Ar-CH{sub 4} plasmas) are comparable to those of natural diamond, and wear damage on counterface materials is minimal. Fundamental tribological studies indicate that these films may undergo phase transformation during long-duration, high-speed and/or high-load sliding tests and that the transformation products trapped at the sliding interfaces can intermittently dominate friction and wear performance. Using results from a combination of TEM, electron diffraction, Raman spectroscopy, and electron energy loss spectroscopy (EELS), they describe the structural chemistry of the debris particles trapped at the sliding interfaces and elucidate their possible effects on friction and wear of NCD films in dry N{sub 2}. Finally, they suggest a few potential applications in which NCD films can improve performance and service lives.

  3. Cutting effectiveness of diamond instruments subjected to cyclic sterilization methods.

    PubMed

    Gureckis, K M; Burgess, J O; Schwartz, R S

    1991-12-01

    The effect of repeated sterilization on the cutting effectiveness of one brand of rotary dental diamond cutting instruments was measured. Four groups of five diamond burs were sterilized by four methods: (1) sterilization with a chemical agent (Sporicidin); (2) steam under pressure (autoclave); (3) dry heat (Dri-Clave); or (4) chemical vapor (Chemiclave). Each group of diamond instruments made a timed cut in a ceramic block. This cut and all subsequent cuts were measured and were used to determine a baseline cutting effectiveness. Each group of diamond burs was then ultrasonically cleaned, sterilized, and another cut was made. At the end of 10 cycles there was no difference in cutting efficiency of the dental diamond instruments. However, there are differences in the cutting efficiency of individual diamond instruments. The SEM evaluation made prior to cutting and at the end of the 10 cycles of sterilization demonstrated that diamond wear was similar in all groups and that little diamond particle loss occurred in any group. PMID:1666657

  4. Wire Electrical Discharge Truing of Metal Bond Diamond Grinding Wheels

    SciTech Connect

    McSpadden, SB

    2002-01-24

    Cylindrical wire EDM profile truing of the metal bond diamond wheel for precision form grinding of ceramics is presented in this report. First a corrosion-resistant, precise spindle with the high-electrical current capability for wire EDM truing of grinding wheel was fabricated. An arc profile was adopted in order to determine form tolerances capabilities of this process. Results show the wire EDM process can generate {micro}m-scale precision form on the diamond wheel efficiently. The wheel, after truing, was used to grind silicon nitride. Grinding forces, surface finish of ground components, and wheel wear were measured. The EDM trued wheel showed a reduction in grinding force from that of the stick dressed wheel. Surface finishes between the two truing methods were similar. In the beginning of the grinding, significant wheel wear rate was identified. The subsequent wheel wear rate stabilized and became considerably lower.

  5. Friction measurement in a hip wear simulator.

    PubMed

    Saikko, Vesa

    2016-05-01

    A torque measurement system was added to a widely used hip wear simulator, the biaxial rocking motion device. With the rotary transducer, the frictional torque about the drive axis of the biaxial rocking motion mechanism was measured. The principle of measuring the torque about the vertical axis above the prosthetic joint, used earlier in commercial biaxial rocking motion simulators, was shown to sense only a minor part of the total frictional torque. With the present method, the total frictional torque of the prosthetic hip was measured. This was shown to consist of the torques about the vertical axis above the joint and about the leaning axis. Femoral heads made from different materials were run against conventional and crosslinked polyethylene acetabular cups in serum lubrication. Regarding the femoral head material and the type of polyethylene, there were no categorical differences in frictional torque with the exception of zirconia heads, with which the lowest values were obtained. Diamond-like carbon coating of the CoCr femoral head did not reduce friction. The friction factor was found to always decrease with increasing load. High wear could increase the frictional torque by 75%. With the present system, friction can be continuously recorded during long wear tests, so the effect of wear on friction with different prosthetic hips can be evaluated.

  6. Opalescent Diamonds Enriched in Hydrocarbon Fluids

    NASA Astrophysics Data System (ADS)

    Leung, I.; Tsao, C.

    2006-05-01

    We studied a large number of diamonds from Liaoning, China. These diamonds are not gem-quality, do not have sharp corners and sharp edges, they are not suitable for making cutting tools. Such industrial diamonds are usually crushed to form abrasives, thus, they might escape the scrutiny of researchers. In China, diamonds were routinely soaked in HF overnight to remove mud and other substances, and no oil and grease were used in the processing. It is not uncommon to see iridescence in pink, pale yellow and grey diamonds. The most common opalescent colors are alternating sharp bands of intense pink and indigo blue, and, less frequently, bands of yellow and blue-green, all may appear in the same diamond. As the bands have uniform thickness, their colors might not be due simply to optical effects, but rather, might be chemically related. We had chosen 10 diamonds to study their FT-IR spectra. Six of the crystals exhibited a group of hydrocarbons (HCs) peaks located just below 3000 cm-1, while all but one had a C-H stretch peak at 3107 cm-1. Two other diamonds had weak HCs peaks, but a very strong peak at 3107 cm-1. Two more diamonds had very weak HCs and C-H stretch peaks. To sum up, when a spectrum has strong HCs peaks, the C-H stretch peak is weak, and vice versa. There seems to be a chemical relationship between the substances represented by these peaks. Our observations indicate that hydrocarbon fluids might have been trapped during crystallization, but subsequently unmixed into well- organized thin bands. If fluids observed in the opalescent diamonds were soaked up in the mantle, then the amount of hydrocarbons existing in Earth's mantle might be quite appreciable in some environment.

  7. Diamond nonlinear photonics

    NASA Astrophysics Data System (ADS)

    Hausmann, B. J. M.; Bulu, I.; Venkataraman, V.; Deotare, P.; Lončar, M.

    2014-05-01

    Despite progress towards integrated diamond photonics, studies of optical nonlinearities in diamond have been limited to Raman scattering in bulk samples. Diamond nonlinear photonics, however, could enable efficient, in situ frequency conversion of single photons emitted by diamond's colour centres, as well as stable and high-power frequency microcombs operating at new wavelengths. Both of these applications depend crucially on efficient four-wave mixing processes enabled by diamond's third-order nonlinearity. Here, we have realized a diamond nonlinear photonics platform by demonstrating optical parametric oscillation via four-wave mixing using single-crystal ultrahigh-quality-factor (1 × 106) diamond ring resonators operating at telecom wavelengths. Threshold powers as low as 20 mW are measured, and up to 20 new wavelengths are generated from a single-frequency pump laser. We also report the first measurement of the nonlinear refractive index due to the third-order nonlinearity in diamond at telecom wavelengths.

  8. Diamond MEMS: wafer scale processing, devices, and technology insertion

    NASA Astrophysics Data System (ADS)

    Carlisle, J. A.

    2009-05-01

    Diamond has long held the promise of revolutionary new devices: impervious chemical barriers, smooth and reliable microscopic machines, and tough mechanical tools. Yet it's been an outsider. Laboratories have been effectively growing diamond crystals for at least 25 years, but the jump to market viability has always been blocked by the expense of diamond production and inability to integrate with other materials. Advances in chemical vapor deposition (CVD) processes have given rise to a hierarchy of carbon films ranging from diamond-like carbon (DLC) to vapor-deposited diamond coatings, however. All have pros and cons based on structure and cost, but they all share some of diamond's heralded attributes. The best performer, in theory, is the purest form of diamond film possible, one absent of graphitic phases. Such a material would capture the extreme hardness, high Young's modulus and chemical inertness of natural diamond. Advanced Diamond Technologies Inc., Romeoville, Ill., is the first company to develop a distinct chemical process to create a marketable phase-pure diamond film. The material, called UNCD® (for ultrananocrystalline diamond), features grain sizes from 3 to 300 nm in size, and layers just 1 to 2 microns thick. With significant advantages over other thin films, UNCD is designed to be inexpensive enough for use in atomic force microscopy (AFM) probes, microelectromechanical machines (MEMS), cell phone circuitry, radio frequency devices, and even biosensors.

  9. Electrically conductive diamond electrodes

    DOEpatents

    Swain, Greg; Fischer, Anne ,; Bennett, Jason; Lowe, Michael

    2009-05-19

    An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

  10. 'Diamond Jenness': A Tough Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic of the target area called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  11. 'Diamond Jenness': Before the Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic of the rock called 'Diamond Jenness' was snapped on sol 177 before NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool, or 'Rat.'

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer. On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  12. 'Diamond Jenness': After the Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic taken by NASA's Mars Exploration Rover Opportunity shows the rock dubbed 'Diamond Jenness.' It was taken on sol 177 (July 23, 2004) after the rover first ground into the rock with its rock abrasion tool, or 'Rat.' The rover later ground into the rock a second time. A sliced spherule, or 'blueberry,' is visible in the upper left corner of the hole.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  13. Does the Use of Diamond-Like Carbon Coating and Organophosphate Lubricant Additive Together Cause Excessive Tribochemical Material Removal?

    SciTech Connect

    Zhou, Yan; Leonard, Donovan N.; Meyer, Harry M.; Luo, Huimin; Qu, Jun

    2015-08-22

    We observe unexpected wear increase on a steel surface that rubbed against diamond-like carbon (DLC) coatings only when lubricated by phosphate-based antiwear additives. Contrary to the literature hypothesis of a competition between zinc dialkyldithiophosphate produced tribofilms and DLC-induced carbon transfer, here a new wear mechanism based on carbon-catalyzed tribochemical interactions supported by surface characterization is proposed

  14. Diamond heteroepitaxial lateral overgrowth

    NASA Astrophysics Data System (ADS)

    Tang, Yung-Hsiu

    This dissertation describes improvements in the growth of single crystal diamond by microwave plasma-assisted chemical vapor deposition (CVD). Heteroepitaxial (001) diamond was grown on 1 cm. 2 a-plane sapphiresubstrates using an epitaxial (001) Ir thin-film as a buffer layer. Low-energy ion bombardment of the Ir layer, a process known as bias-enhanced nucleation, is a key step in achieving a high density of diamond nuclei. Bias conditions were optimized to form uniformly-high nucleation densities across the substrates, which led to well-coalesced diamond thin films after short growth times. Epitaxial lateral overgrowth (ELO) was used as a means of decreasing diamond internal stress by impeding the propagation of threading dislocations into the growing material. Its use in diamond growth requires adaptation to the aggressive chemical and thermal environment of the hydrogen plasma in a CVD reactor. Three ELO variants were developed. The most successful utilized a gold (Au) mask prepared by vacuum evaporation onto the surface of a thin heteroepitaxial diamond layer. The Au mask pattern, a series of parallel stripes on the micrometer scale, was produced by standard lift-off photolithography. When diamond overgrows the mask, dislocations are largely confined to the substrate. Differing degrees of confinement were studied by varying the stripe geometry and orientation. Significant improvement in diamond quality was found in the overgrown regions, as evidenced by reduction of the Raman scattering linewidth. The Au layer was found to remain intact during diamond overgrowth and did not chemically bond with the diamond surface. Besides impeding the propagation of threading dislocations, it was discovered that the thermally-induced stress in the CVD diamond was significantly reduced as a result of the ductile Au layer. Cracking and delamination of the diamond from the substrate was mostly eliminated. When diamond was grown to thicknesses above 0.1 mm it was found that

  15. Diamond bio electronics.

    PubMed

    Linares, Robert; Doering, Patrick; Linares, Bryant

    2009-01-01

    The use of diamond for advanced applications has been the dream of mankind for centuries. Until recently this dream has been realized only in the use of diamond for gemstones and abrasive applications where tons of diamonds are used on an annual basis. Diamond is the material system of choice for many applications, but its use has historically been limited due to the small size, high cost, and inconsistent (and typically poor) quality of available diamond materials until recently. The recent development of high quality, single crystal diamond crystal growth via the Chemical Vapor Deposition (CVD) process has allowed physcists and increasingly scientists in the life science area to think beyond these limitations and envision how diamond may be used in advanced applications ranging from quantum computing, to power generation and molecular imaging, and eventually even diamond nano-bots. Because of diamond's unique properties as a bio-compatible material, better understanding of diamond's quantum effects and a convergence of mass production, semiconductor-like fabrication process, diamond now promises a unique and powerful key to the realization of the bio-electronic devices being envisioned for the new era of medical science. The combination of robust in-the-body diamond based sensors, coupled with smart bio-functionalized diamond devices may lead to diamond being the platform of choice for bio-electronics. This generation of diamond based bio-electronic devices would contribute substantially to ushering in a paradigm shift for medical science, leading to vastly improved patient diagnosis, decrease of drug development costs and risks, and improved effectiveness of drug delivery and gene therapy programs through better timed and more customized solutions.

  16. Diamond bio electronics.

    PubMed

    Linares, Robert; Doering, Patrick; Linares, Bryant

    2009-01-01

    The use of diamond for advanced applications has been the dream of mankind for centuries. Until recently this dream has been realized only in the use of diamond for gemstones and abrasive applications where tons of diamonds are used on an annual basis. Diamond is the material system of choice for many applications, but its use has historically been limited due to the small size, high cost, and inconsistent (and typically poor) quality of available diamond materials until recently. The recent development of high quality, single crystal diamond crystal growth via the Chemical Vapor Deposition (CVD) process has allowed physcists and increasingly scientists in the life science area to think beyond these limitations and envision how diamond may be used in advanced applications ranging from quantum computing, to power generation and molecular imaging, and eventually even diamond nano-bots. Because of diamond's unique properties as a bio-compatible material, better understanding of diamond's quantum effects and a convergence of mass production, semiconductor-like fabrication process, diamond now promises a unique and powerful key to the realization of the bio-electronic devices being envisioned for the new era of medical science. The combination of robust in-the-body diamond based sensors, coupled with smart bio-functionalized diamond devices may lead to diamond being the platform of choice for bio-electronics. This generation of diamond based bio-electronic devices would contribute substantially to ushering in a paradigm shift for medical science, leading to vastly improved patient diagnosis, decrease of drug development costs and risks, and improved effectiveness of drug delivery and gene therapy programs through better timed and more customized solutions. PMID:19745488

  17. Molecular dynamics simulations of wear processes

    NASA Astrophysics Data System (ADS)

    Yu, Hualiang

    Wear has been recognized as a vital problem in many industries. It results in a loss of durability, reliability, and efficiency and costs tens of billions of dollars annually. Significant effort has been devoted in both experimental and theoretical studies. However, the mechanisms of wear are still poorly understood and therefore wear control is far behind its demand. One way to study wear process is via computer simulation, which has become more powerful with the rapid development in computer facilities and efficient algorithms. It allows observation of atomic scale deformation and therefore it is a very good tool to study wear mechanisms at the nano-scale. This study presents a series of molecular dynamic simulation of some nano-scale wear processes, such as indentation and plowing, with the goal of exploring the factors that affect wear and predicting wear for different conditions. Molecular Dynamics simulations were carried out on a system that includes an aluminum substrate and a hard tip. Embedded atom method (EAM) and Lennard-Jones potentials were used to describe interactions between atoms. For nano-indentation simulations, both constant indent force and constant loading speed were applied to study the wear mechanisms as well as material properties. Some phenomenon, such as jump-to-contact, local melting, and dislocation nucleation were observed. More importantly, the effects of system temperature, indent force, substrate orientation, tip-substrate bond, indenter shape, boundary condition, and defect concentrations of the substrate were systematically investigated during indentation. The results are in qualitative agreement with limited experimental data. Similar simulations were carried out for plowing. The effects of plowing force, substrate orientation, the tip-substrate bond, and alloy elements are discussed based on the simulation results. In addition, a simple analytic model of plowing behavior is provided. The model reveals two parameters, static

  18. Diamond Synthesis Employing Nanoparticle Seeds

    NASA Technical Reports Server (NTRS)

    Uppireddi, Kishore (Inventor); Morell, Gerardo (Inventor); Weiner, Brad R. (Inventor)

    2014-01-01

    Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

  19. Diamonds for beam instrumentation

    SciTech Connect

    Griesmayer, Erich

    2013-04-19

    Diamond is perhaps the most versatile, efficient and radiation tolerant material available for use in beam detectors with a correspondingly wide range of applications in beam instrumentation. Numerous practical applications have demonstrated and exploited the sensitivity of diamond to charged particles, photons and neutrons. In this paper, a brief description of a generic diamond detector is given and the interaction of the CVD diamond detector material with protons, electrons, photons and neutrons is presented. Latest results of the interaction of sCVD diamond with 14 MeV mono-energetic neutrons are shown.

  20. Finite element based simulation of dry sliding wear

    NASA Astrophysics Data System (ADS)

    Hegadekatte, V.; Huber, N.; Kraft, O.

    2005-01-01

    In order to predict wear and eventually the life-span of complex mechanical systems, several hundred thousand operating cycles have to be simulated. Therefore, a finite element (FE) post-processor is the optimum choice, considering the computational expense. A wear simulation approach based on Archard's wear law is implemented in an FE post-processor that works in association with a commercial FE package, ABAQUS, for solving the general deformable-deformable contact problem. Local wear is computed and then integrated over the sliding distance using the Euler integration scheme. The wear simulation tool works in a loop and performs a series of static FE-simulations with updated surface geometries to get a realistic contact pressure distribution on the contacting surfaces. It will be demonstrated that this efficient approach can simulate wear on both two-dimensional and three-dimensional surface topologies. The wear on both the interacting surfaces is computed using the contact pressure distribution from a two-dimensional or three-dimensional simulation, depending on the case. After every wear step the geometry is re-meshed to correct the deformed mesh due to wear, thus ensuring a fairly uniform mesh for further processing. The importance and suitability of such a wear simulation tool will be enunciated in this paper.

  1. Prepolishing on a CNC platform with bound abrasive contour tools

    NASA Astrophysics Data System (ADS)

    Schoeffler, Adrienne E.; Gregg, Leslie L.; Schoen, John M.; Fess, Edward M.; Hakiel, Michael; Jacobs, Stephen D.

    2003-05-01

    Deterministic microgrinding (DMG) of optical glasses and ceramics is the commercial manufacturing process of choice to shape glass surfaces prior to final finishing. This process employs rigid bound matrix diamond tooling resulting in surface roughness values of 3-5μm peak to valley and 100-400nm rms, as well as mid-spatial frequency tool marks that require subsequent removal in secondary finishing steps. The ability to pre-polish optical surfaces within the grinding platform would reduce final finishing process times. Bound abrasive contour wheels containing cerium oxide, alumina or zirconia abrasives were constructed with an epoxy matrix. The effects of abrasive type, composition, and erosion promoters were examined for tool hardness (Shore D), and tested with commercial optical glasses in an Optipro CNC grinding platform. Metrology protocols were developed to examine tool wear and subsequent surface roughness. Work is directed to demonstrating effective material removal, improved surface roughness and cutter mark removal.

  2. FIBROUS MONOLITH WEAR RESISTANT COMPONENTS FOR THE MINING INDUSTRY

    SciTech Connect

    Kenneth L. Knittel

    2005-05-09

    The work performed on this program was to develop wear resistant, tough FM composite materials with efforts focused on WC-Co based FM systems. The materials were developed for use in mining industry wear applications. Components of interest were drill bit inserts for drilling blast holes. Other component applications investigated included wear plates for a variety of equipment such as pit shovels, wear surfaces for conveyors, milling media for ball milling operations, hydrocyclone cones, grader blades and dozer teeth. Cross-cutting technologies investigated included hot metal extrusion dies, drill bits for circuit board fabrication, cutting tools for cast iron and aluminum machining. An important part of the work was identification of the standard materials used in drilling applications. A materials trade study to determine those metals and ceramics used for mining applications provided guidance for the most important materials to be investigated. WC-Co and diamond combinations were shown to have the most desirable properties. Other considerations such as fabrication technique and the ability to consolidate shifted the focus away from diamond materials and toward WC-Co. Cooperating partners such as Kennametal and Kyocera assisted with supplies, evaluations of material systems, fabricated parts and suggestions for cross-cutting technology applications for FM architectures. Kennametal provided the raw materials (WC-Co and Al-TiCN powders) for the extent of the material evaluations. Kyocera shared their research into various FM systems and provided laboratory testing of fabricated materials. Kyocera also continued research of the FM systems with the intention of developing commercial markets for a variety of applications. The continued development of FM technology by Kyocera is seen as a direct result of the cooperation established under this funding. Kyocera has a specific interest in the commercial development of the FM technology and have licensed it and have paid

  3. The Nature of Diamonds

    NASA Astrophysics Data System (ADS)

    Harlow, George E.

    1997-10-01

    The paragon of physical perfection and a sparkling example of Earth's forces at work, the diamond has fascinated all realms of society, from starlets to scientists. The Nature of Diamonds is a comprehensive look at nature's most coveted gem. A handsome, large-format book, The Nature of Diamonds is an authoritative and richly-illustrated tribute to the diamond. Leading geologists, gemologists, physicists, and cultural observers cover every facet of the stone, from its formation in the depths of the Earth, its ascent to the surface, and its economic, regal, social, and technological roles. Cutting-edge research takes the reader to the frontiers of diamond exploration and exploitation, from the Arctic wastes to the laboratories where diamonds are created for massive road shredders that rip up and then re-create superhighways. Here also is an overview of cutting, from the rough stones in Roman rings to the highly-faceted stones we see today, and a glimpse into the business of diamonds. Finally, The Nature of Diamonds chronicles scientific and cultural history and explores the diamond as both a sacred and a social symbol, including a picture history of betrothal rings. Wide-ranging illustrations explain the geology of diamonds, chart the history of mining from its origins in India and Brazil through the diamond rush in South Africa and today's high-tech enterprises, and capture the brilliance and beauty of this extraordinary gem. _

  4. Thermally stable diamond brazing

    DOEpatents

    Radtke, Robert P.

    2009-02-10

    A cutting element and a method for forming a cutting element is described and shown. The cutting element includes a substrate, a TSP diamond layer, a metal interlayer between the substrate and the diamond layer, and a braze joint securing the diamond layer to the substrate. The thickness of the metal interlayer is determined according to a formula. The formula takes into account the thickness and modulus of elasticity of the metal interlayer and the thickness of the TSP diamond. This prevents the use of a too thin or too thick metal interlayer. A metal interlayer that is too thin is not capable of absorbing enough energy to prevent the TSP diamond from fracturing. A metal interlayer that is too thick may allow the TSP diamond to fracture by reason of bending stress. A coating may be provided between the TSP diamond layer and the metal interlayer. This coating serves as a thermal barrier and to control residual thermal stress.

  5. Structures and Mechanical Properties of Natural and Synthetic Diamonds. Chapter 8

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1998-01-01

    A revolution in diamond technology is in progress as the low-pressure process becomes an industrial reality. It will soon be possible to take advantage of the demanding properties of diamond to develop a myriad of new applications, particularly for self-lubricating, wear, and superhard coatings. The production of large diamond films or sheets at low cost, a distinct possibility in the not-too-distant future, may drastically change tribology technology, particularly solid lubricants and lubricating materials and systems. This chapter reviews the structures and properties of natural and synthetic diamond to gain a better understanding of the tribological properties of diamond and related materials to be described in the following chapters. Atomic and crystal structure, impurities, mechanical properties, and indentation hardness of diamond are described.

  6. Raman spectroscopy of diamond and doped diamond.

    PubMed

    Prawer, Steven; Nemanich, Robert J

    2004-11-15

    The optimization of diamond films as valuable engineering materials for a wide variety of applications has required the development of robust methods for their characterization. Of the many methods used, Raman microscopy is perhaps the most valuable because it provides readily distinguishable signatures of each of the different forms of carbon (e.g. diamond, graphite, buckyballs). In addition it is non-destructive, requires little or no specimen preparation, is performed in air and can produce spatially resolved maps of the different forms of carbon within a specimen. This article begins by reviewing the strengths (and some of the pitfalls) of the Raman technique for the analysis of diamond and diamond films and surveys some of the latest developments (for example, surface-enhanced Raman and ultraviolet Raman spectroscopy) which hold the promise of providing a more profound understanding of the outstanding properties of these materials. The remainder of the article is devoted to the uses of Raman spectroscopy in diamond science and technology. Topics covered include using Raman spectroscopy to assess stress, crystalline perfection, phase purity, crystallite size, point defects and doping in diamond and diamond films.

  7. Wear Measurement System

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Lewis Research Center developed a tribometer for in-house wear tests. Implant Sciences Corporation (ISC), working on a NASA contract to develop coatings to enhance the wear capabilities of materials, adapted the tribometer for its own use and developed a commercial line of user-friendly systems. The ISC-200 is a pin-on-disk type of tribometer, functioning like a record player and creating a wear groove on the disk, with variables of speed and load. The system can measure the coefficient of friction, the wear behavior between materials, and the integrity of thin films or coatings. Applications include measuring wear on contact lenses and engine parts and testing disk drives.

  8. Discrimination of metamorphic diamond populations by Raman spectroscopy (Kokchetav, Kazakhstan).

    PubMed

    Korsakov, Andrey V; Vandenabeele, Peter; Theunissen, Karel

    2005-08-01

    Metamorphic diamond is a powerful but frequently debated indicator for ultrahigh-pressure metamorphic (UHPM) conditions. Because of their small size, their optical identification needs confirmation. Characteristics of chemically extracted microdiamonds from Kokchetav, identified by different analytical methods, are used here for unambiguous in situ identification by Raman microspectroscopy. Differences appear in the diamond spectra and the Raman analytical method is explored as a helpful tool in the discrimination between diamond populations from four different UHPM lithologies of Kokchetav. Not considering the graphite-coated diamond, out of the reach of the laser wavelength used here, the comparison of these Kokchetav Raman spectra may provide additional information in other UHPM studies. PMID:16029860

  9. Discrimination of metamorphic diamond populations by Raman spectroscopy (Kokchetav, Kazakhstan).

    PubMed

    Korsakov, Andrey V; Vandenabeele, Peter; Theunissen, Karel

    2005-08-01

    Metamorphic diamond is a powerful but frequently debated indicator for ultrahigh-pressure metamorphic (UHPM) conditions. Because of their small size, their optical identification needs confirmation. Characteristics of chemically extracted microdiamonds from Kokchetav, identified by different analytical methods, are used here for unambiguous in situ identification by Raman microspectroscopy. Differences appear in the diamond spectra and the Raman analytical method is explored as a helpful tool in the discrimination between diamond populations from four different UHPM lithologies of Kokchetav. Not considering the graphite-coated diamond, out of the reach of the laser wavelength used here, the comparison of these Kokchetav Raman spectra may provide additional information in other UHPM studies.

  10. Inclusions of Hydrocarbon Fluids in Diamonds From Wafangdian, Liaoning, China

    NASA Astrophysics Data System (ADS)

    Leung, I. S.; Tsao, C.

    2015-12-01

    We studied a large number of industrial-grade diamonds from Pipe 50 of Liaoning, China. These diamonds are not suitable for polishing into gems or making cutting tools. They are usually crushed to form abrasives, without much scientific scrutiny. We report here fluid inclusions in dozens of diamonds. The first type of fluids occur in the outer rim of diamonds, just below the surface, while their interior is free of visible fluids. Under UV radiation, when a non-fluorescent diamond appeared dim, bubbles of included fluids became visible as yellow and blue spherules. Such diamonds are sometimes encrusted with euhedral micro-diamonds resembling those on thin films grown by CVD. The second type of fluid-rich diamonds display iridescence of pink, blue, green and yellow colors. They show lamellar, filamentous, or tubular structures, some of the tubes are filled with granules, probably grown from fluids in the tubes. An FT-IR investigation of both types yielded similar results. Apart from absorption due to intrinsic diamond lattice vibrations, we found an outstanding group of bands just below wavenumber 3000. This indicates the presence of a saturated aliphatic hydrocarbons of long chain length. Our results seem to implicate that hydrocarbons might be an important component in Earth's mantle, which might even have provided carbon from which diamonds crystllized.

  11. Nano-inclusions in diamond: Evidence of diamond genesis

    NASA Astrophysics Data System (ADS)

    Wirth, R.

    2015-12-01

    The use of Focused Ion Beam technology (FIB) for TEM sample preparation introduced approximately 15 years ago revolutionized the application of TEM in Geosciences. For the first time, FIB enabled cutting samples for TEM use from exactly the location we are interested in. Applied to diamond investigation, this technique revealed the presence of nanometre-sized inclusions in diamond that have been simply unknown before. Nanoinclusions in diamond from different location and origin such as diamonds from the Lower and Upper Mantle, metamorphic diamonds (Kazakhstan, Erzgebirge, Bohemia), diamonds from ophiolites (Tibet, Mongolia, Xinjiang, Ural Mountains), diamonds from igneous rocks (Hawaii, Kamchatka) and impact diamonds (Popigai Crater, Siberia) have been investigated during the last 15 years. The major conclusion of all these TEM studies is, that the nanoinclusions, their phases and phase composition together with the micro- and nanostructure evidence the origin of diamond and genesis of diamond. We can discriminate Five different mechanisms of diamond genesis in nature are observed: Diamond crystallized from a high-density fluid (Upper mantle and metamorphic diamond). Diamond crystallized from carbonatitic melt (Lower mantle diamond). Diamond precipitates from a metal alloy melt (Diamond from ophiolites). Diamond crystallized by gas phase condensation or chemical vapour condensation (CVD) (Lavas from Kamchatka, xenoliths in Hawaiian lavas). Direct transformation of graphite into diamond.

  12. Quantitative wear and wear damage analysis of composite resins in vitro.

    PubMed

    Koottathape, Natthavoot; Takahashi, Hidekazu; Iwasaki, Naohiko; Kanehira, Masafumi; Finger, Werner J

    2014-01-01

    The aim of this study was to investigate volume loss and worn surfaces' morphologies of eight composite resins: Durafill VS (DUR), Clearfil AP-X (APX), Filtek Z250 (Z250), Filtek Supreme XT (FIL), Kalore (KAL), MI Flow (MFL), Venus Diamond (VED) and Venus Pearl (VEP). Disc-shaped specimens were fabricated and mounted in a ball-on-disc wear testing machine and abraded in water or with the third-body media, poppy seed slurry and polymethyl methacrylate (PMMA) slurry. Volume loss (n=5) was determined after 50k sliding cycles, and analyzed using two-way ANOVA (α=0.05). The worn surfaces were examined with SEM. Two-way ANOVA suggested significant interaction between composite and wear condition. DUR, KAL and MFL showed low wear in water. DUR, Z250 and FIL showed moderate wear with PMMA slurry, whereas APX, KAL and MFL were deeper abraded. Under the action of poppy seed slurry DUR proved high volume loss. SEM showed that Z250, FIL and MFL were uniformly abraded in water. KAL and MFL with poppy seed were heavily destructed, whereas VED and VEP appeared very smooth. KAL and MFL abraded with PMMA slurry showed many cracks, but VEP remained crack-free and smooth. Volume loss and worn surfaces' morphologies varied with type of composite and third-body media used. PMID:24219861

  13. Drill wear monitoring in cortical bone drilling.

    PubMed

    Staroveski, Tomislav; Brezak, Danko; Udiljak, Toma

    2015-06-01

    Medical drills are subject to intensive wear due to mechanical factors which occur during the bone drilling process, and potential thermal and chemical factors related to the sterilisation process. Intensive wear increases friction between the drill and the surrounding bone tissue, resulting in higher drilling temperatures and cutting forces. Therefore, the goal of this experimental research was to develop a drill wear classification model based on multi-sensor approach and artificial neural network algorithm. A required set of tool wear features were extracted from the following three types of signals: cutting forces, servomotor drive currents and acoustic emission. Their capacity to classify precisely one of three predefined drill wear levels has been established using a pattern recognition type of the Radial Basis Function Neural Network algorithm. Experiments were performed on a custom-made test bed system using fresh bovine bones and standard medical drills. Results have shown high classification success rate, together with the model robustness and insensitivity to variations of bone mechanical properties. Features extracted from acoustic emission and servomotor drive signals achieved the highest precision in drill wear level classification (92.8%), thus indicating their potential in the design of a new type of medical drilling machine with process monitoring capabilities.

  14. Drill wear monitoring in cortical bone drilling.

    PubMed

    Staroveski, Tomislav; Brezak, Danko; Udiljak, Toma

    2015-06-01

    Medical drills are subject to intensive wear due to mechanical factors which occur during the bone drilling process, and potential thermal and chemical factors related to the sterilisation process. Intensive wear increases friction between the drill and the surrounding bone tissue, resulting in higher drilling temperatures and cutting forces. Therefore, the goal of this experimental research was to develop a drill wear classification model based on multi-sensor approach and artificial neural network algorithm. A required set of tool wear features were extracted from the following three types of signals: cutting forces, servomotor drive currents and acoustic emission. Their capacity to classify precisely one of three predefined drill wear levels has been established using a pattern recognition type of the Radial Basis Function Neural Network algorithm. Experiments were performed on a custom-made test bed system using fresh bovine bones and standard medical drills. Results have shown high classification success rate, together with the model robustness and insensitivity to variations of bone mechanical properties. Features extracted from acoustic emission and servomotor drive signals achieved the highest precision in drill wear level classification (92.8%), thus indicating their potential in the design of a new type of medical drilling machine with process monitoring capabilities. PMID:25922212

  15. CVD Diamond, DLC, and c-BN Coatings for Solid Film Lubrication

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Murakawa, Masao; Watanabe, Shuichi; Takeuchi, Sadao; Miyake, Shojiro; Wu, Richard L. C.

    1998-01-01

    The main criteria for judging coating performance were coefficient of friction and wear rate, which had to be less than 0.1 and 10(exp -6) cubic MM /(N*m), respectively. Carbon- and nitrogen-ion-implanted, fine-grain, chemical-vapor-deposited (CVD) diamond and diamondlike carbon (DLC) ion beam deposited on fine-grain CVD diamond met the criteria regardless of environment (vacuum, nitrogen, and air).

  16. CVD Diamond, DLC, and c-BN Coatings for Solid Film Lubrication

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1998-01-01

    When the main criteria for judging coating performance were coefficient of friction and wear rate, which had to be less than 0.1 and 10(exp -6) mm(exp 3)/N-m, respectively, carbon- and nitrogen-ion-implanted, fine-grain CVD diamond and DLC ion beam deposited on fine-grain CVD diamond met the requirements regardless of environment (vacuum, nitrogen, and air).

  17. Fabrication and testing of diamond-machined gratings in ZnSe, GaP, and bismuth germanate for the near infrared and visible

    SciTech Connect

    Kuzmenko, P J; Little, S L; Ikeda, Y; Kobayashi, N

    2008-06-22

    High quality immersion gratings for infrared applications have been demonstrated in silicon and germanium. To extend this technology to shorter wavelengths other materials must be investigated. We selected three materials, zinc selenide, gallium phosphide and bismuth germanate (Bi{sub 4}Ge{sub 3}O{sub 12}), based on high refractive index, good visible transmission and commercial availability in useful sizes. Crystal samples were diamond turned on an ultra-precision lathe to identify preferred cutting directions. Using this information we diamond-flycut test gratings over a range of feed rates to determine the optimal cutting conditions. For both ZnSe and GaP good surface quality was achieved at feed rates up to 1.0 cm/minute using a special compound angle diamond tool with negative rake angles on both cutting surfaces. The surface roughness of the groove facets was about 4 nm. A Zygo interferometer measured grating wavefront errors in reflection. For the ZnSe the RMS error was < {lambda}/20 at 633nm. More extensive testing was performed with a HeNe laser source and a cooled CCD camera. These measurements demonstrated high relative diffraction efficiency (> 80%), low random groove error (2.0 nm rms), and Rowland ghost intensities at < 0.1%. Preliminary tests on bismuth germanate show high tool wear.

  18. Fabrication and testing of diamond-machined gratings in ZnSe, GaP, and bismuth germanate for the near-infrared and visible

    NASA Astrophysics Data System (ADS)

    Kuzmenko, Paul J.; Little, Steve L.; Ikeda, Yuji; Kobayashi, Naoto

    2008-07-01

    High quality immersion gratings for infrared applications have been demonstrated in silicon and germanium. To extend this technology to shorter wavelengths other materials must be investigated. We selected three materials, zinc selenide, gallium phosphide and bismuth germanate (Bi4Ge3O12), based on high refractive index, good visible transmission and commercial availability in useful sizes. Crystal samples were diamond turned on an ultra-precision lathe to identify preferred cutting directions. Using this information we diamond-flycut test gratings over a range of feed rates to determine the optimal cutting conditions. For both ZnSe and GaP good surface quality was achieved at feed rates up to 1.0 cm/minute using a special compound angle diamond tool with negative rake angles on both cutting surfaces. The surface roughness of the groove facets was about 4 nm. A Zygo interferometer measured grating wavefront errors in reflection. For the ZnSe the RMS error was < λ/20 @633nm. More extensive testing was performed with a HeNe laser source and a cooled CCD camera. These measurements demonstrated high relative diffraction efficiency (> 80%), low random groove error (2.0 nm rms), and Rowland ghost intensities at < 0.1%. Preliminary tests on bismuth germanate show high tool wear.

  19. Multiple Diamond Anvil (MDA) apparatus using nano-polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Irifune, T.; Kunimoto, T.; Tange, Y.; Shinmei, T.; Isobe, F.; Kurio, A.; Funakoshi, K.

    2011-12-01

    Thanks to the great efforts by Dave Mao, Bill Bassett, Taro Takahashi, and their colleagues at the University of Rochester through 1960s-70s, diamond anvil cell (DAC) became a major tool to investigate the deep Earth after its invention by scientists at NBS in 1958. DAC can now cover almost the entire pressure and temperature regimes of the Earth's interior, which seems to have solved the longstanding debate on the crystal structure of iron under the P-T conditions of the Earth's inner core. In contrast, various types of static large-volume presses (LVP) have been invented, where tungsten carbide has conventionally been used as anvils. Kawai-type multianvil apparatus (MA), which utilize 6 first-stage harden steel and 8 tungsten carbide anvils, is the most successful LVP, and has been used for accurate measurements of phase transitions, physical properties, element partitioning, etc. at high pressure and temperature. However, pressures using tungsten carbide as the second-stage anvils have been limited to about 30 GPa due to significant plastic deformation of the anvils. Efforts have been made to expand this pressure limit by replacing tungsten carbide anvils with harder sintered diamond (SD) anvils over the last two decades, but the pressures available in KMA with SD anvils have still been limited to below 100 GPa. We succeeded to produce nano-polycrystalline diamond (NPD or HIME-Diamond) in 2003, which is known to have ultrahigh hardness, very high toughness and elastic stiffness, high transmittance of light, relatively low thermal conductivity. These properties are feasible for its use as anvils, and some preliminary experiments of application of NPD anvils to laser heated DAC have successfully made in the last few years. We are now able to synthesize NPD rods with about 1cm in both diameter and length using a newly constructed 6000-ton KMA at Geodynamics Research Center, Ehime University, and have just started to apply this new polycrystalline diamond as anvils

  20. Predicted wear resistances of binary carbide coatings

    SciTech Connect

    Kramer, B.M.

    1986-11-01

    A mechanistic model of the tool wear process has been presented (B. M. Kramer and P. K. Judd, J. Vac. Sci. Technol. A 3, 2439 (1985)) that includes the effects of both the abrasion of the tool material by inclusions within the workpiece and the chemical dissolution of the tool material into the matrix of the workpiece. Machining tests have been run on steel with titanium carbide coated tooling and the resulting test data have been employed to produce a rough calibration of the proposed model. This model has been used to predict the wear resistances of the other group IV B carbides and of the (Ti,Hf)C system in the machining of steel.

  1. Wear Modeling: Evaluation and Categorization of Wear Models

    NASA Astrophysics Data System (ADS)

    Meng, Hsien-Chung

    The objective of this study was to evaluate progress in wear modeling and propose guidelines for future work. Such guidelines can help wear modelers to make appropriate decisions and ascertain information relevant to wear modeling. Over 5,000 papers in the literature were surveyed. 182 erosion wear and sliding wear equations proposed between 1957 and 1992 were found and studied. Two approaches were taken to analyze the surveyed models. The first approach focuses on common features and variations in each of five wear modeling steps. The second approach identifies characteristics of the overall development of wear modeling. The conclusions and recommendations of this study: (1) No single universal equation or extensively accepted theory fully explains the many types of wear behavior. (2) Wear mechanisms as typically described in research literature are not fundamental processes of material loss. Mechanical, chemical, physical and metallurgical action are the four fundamental processes: future wear models should include consideration of these four simultaneously, together with their interactions. (3) Wear models based on a single academic discipline cannot fully explain a wearing process even if for a single wear mechanism. An interdisciplinary approach should be applied to build wear models. (4) Two characteristics in past development of wear modeling are positive and should be carried into future work: (a) progressively more and more local information about the variations of working conditions has been considered in wear modeling, and (b) the approaches of different disciplines has been more frequently and extensively applied together to build wear models which explain progressively more wear phenomena in a wearing system. (5) Wear modelers should derive wear equations to concisely present research results and to complete wear modeling. Out of the 5000 papers considered in this study, only 182 presented equations as well as word descriptions to describe erosion and

  2. Ultrasound effects on the tribological properties of synthesized diamond films

    SciTech Connect

    Snikta, V.; Trava-Airoldi, V.J.; Baranauskas, V.

    1995-09-01

    The friction and wear behavior of chemical vapor deposition grown diamond films has been investigated under strong ultrasound conditions at the friction interface. Experiments were performed on an alternating {open_quotes}pin-on-plate{close_quotes} tribometer constructed as an ultrasonic motor with excited bimodal mechanical vibrations at the frequency of 20 kHz. Ultrasound sliding of the films was done against alumina ceramics and with the diamond film itself. We have shown that chemical vapor deposition diamond films can be fast polished mechanically without significant graphitization by ultrasonic treatment. The initial film roughness was reduced from an average R{sub a} {approximately}3000 nm to R{sub a} {approximately}10 nm. The polishing decreased the static coefficient of friction of the diamond film from about 0.53 to about 0.12. The operative mechanism for the polishing in the case of initially rough diamond samples appears to be asperity fracture. For smooth diamond samples it is suggested that tribochemical oxidation is also a polishing mechanism. 17 refs., 8 figs.

  3. Diamond nucleation using polyethene

    DOEpatents

    Morell, Gerardo; Makarov, Vladimir; Varshney, Deepak; Weiner, Brad

    2013-07-23

    The invention presents a simple, non-destructive and non-abrasive method of diamond nucleation using polyethene. It particularly describes the nucleation of diamond on an electrically viable substrate surface using polyethene via chemical vapor deposition (CVD) technique in a gaseous environment.

  4. Diamond Nucleation Using Polyethene

    NASA Technical Reports Server (NTRS)

    Morell, Gerardo (Inventor); Makarov, Vladimir (Inventor); Varshney, Deepak (Inventor); Weiner, Brad (Inventor)

    2013-01-01

    The invention presents a simple, non-destructive and non-abrasive method of diamond nucleation using polyethene. It particularly describes the nucleation of diamond on an electrically viable substrate surface using polyethene via chemical vapor deposition (CVD) technique in a gaseous environment.

  5. Diamond films: Historical perspective

    SciTech Connect

    Messier, R.

    1993-01-01

    This section is a compilation of notes and published international articles about the development of methods of depositing diamond films. Vapor deposition articles are included from American, Russian, and Japanese publications. The international competition to develop new deposition methodologies is stressed. The current status of chemical vapor deposition of diamond is assessed.

  6. Cutting tool study: 21-6-9 stainless steel

    SciTech Connect

    McManigle, A.P.

    1992-07-29

    The Rocky Flats Plant conducted a study to test cermet cutting tools by performing machinability studies on War Reserve product under controlled conditions. The purpose of these studies was to determine the most satisfactory tools that optimize tool life, minimize costs, improve reliability and chip control, and increase productivity by performing the operations to specified Accuracies. This study tested three manufacturers` cermet cutting tools and a carbide tool used previously by the Rocky Flats Plant for machining spherical-shaped 21-6-9 stainless steel forgings (Figure 1). The 80-degree diamond inserts were tested by experimenting with various chip-breaker geometries, cutting speeds, feedrates, and cermet grades on the outside contour roughing operation. The cermets tested were manufactured by Kennametal, Valenite, and NTK. The carbide tool ordinarily used for this operation is manufactured by Carboloy. Evaluation of tho tools was conducted by investigating the number of passes per part and parts per insert, tool wear, cutting time, tool life, surface finish, and stem taper. Benefits to be gained from this study were: improved part quality, better chip control, increased tool life and utilization, and greater fabrication productivity. This was to be accomplished by performing the operation to specified accuracies within the scope of the tools tested.

  7. Method for growth of CVD diamond on thin film refractory coatings and glass ceramic materials

    NASA Astrophysics Data System (ADS)

    Moran, Mark B.; Johnson, Linda F.; Klemm, Karl A.

    1994-09-01

    the application of diamond coatings to cutting-tool inserts.

  8. Study on effect of plasma surface treatments for diamond deposition by DC arc plasmatron.

    PubMed

    Kang, In-Je; Joa, Sang-Beom; Lee, Heon-Ju

    2013-11-01

    To improve the thermal conductivity and wear resistance of ceramic materials in the field of renewable energy technologies, diamond coating by plasma processing has been carried out in recent years. This study's goal is to improve diamond deposition on Al2O3 ceramic substrates by plasma surface treatments. Before diamond deposition was carried out in a vacuum, plasma surface treatments using Ar gas were conducted to improve conditions for deposition. We also conducted plasma processing for diamond deposition on Al2O3 ceramic substrates using a DC arc Plasmatron. The Al2O3 ceramic substrates with diamond film (5 x 15 mm2), were investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then, the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) was studied. We identified nanocrystalline diamond films on the Al2O3 ceramic substrates. The results showed us that the deposition rate of diamond films was 2.3 microm/h after plasma surface treatments. Comparing the above result with untreated ceramic substrates, the deposition rate improved with the surface roughness of the deposited diamond films.

  9. Study on effect of plasma surface treatments for diamond deposition by DC arc plasmatron.

    PubMed

    Kang, In-Je; Joa, Sang-Beom; Lee, Heon-Ju

    2013-11-01

    To improve the thermal conductivity and wear resistance of ceramic materials in the field of renewable energy technologies, diamond coating by plasma processing has been carried out in recent years. This study's goal is to improve diamond deposition on Al2O3 ceramic substrates by plasma surface treatments. Before diamond deposition was carried out in a vacuum, plasma surface treatments using Ar gas were conducted to improve conditions for deposition. We also conducted plasma processing for diamond deposition on Al2O3 ceramic substrates using a DC arc Plasmatron. The Al2O3 ceramic substrates with diamond film (5 x 15 mm2), were investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then, the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) was studied. We identified nanocrystalline diamond films on the Al2O3 ceramic substrates. The results showed us that the deposition rate of diamond films was 2.3 microm/h after plasma surface treatments. Comparing the above result with untreated ceramic substrates, the deposition rate improved with the surface roughness of the deposited diamond films. PMID:24245257

  10. Rig for testing the relative wear resistance of materials

    SciTech Connect

    Berdikov, V.F.; Diulin, A.I.; Efimchuk, V.P.; Pushkarev, O.I.; Finogenov, G.P.

    1987-01-01

    The authors have developed a simple and compact rig for studying the relative wear resistance of materials subjected to mechanical abrasion and friction. The rig has an electronic control system. It was used to test the relative wear resistance of a wide range of superhard and brittle materials under mechanical abrasion against a counterbody. The counterbody was made of modified iron and the test medium was a diamond suspension in oil. The results showed that specimen wear exhibits a linear relationship with abrasion time (in the range of 0.5-20 min.) at unit pressure from 0.01 to 0.10 MPa. That a standard wear pattern exists within a wide range of parameters indicates that abrasive conditions are highly stable and makes it possible to control conditions. The rig was used to establish the relative wear resistance of several abrasives, minerals, and refractory compounds. The very large difference (15.2 times) between the most and least-resistant materials (tungsten carbide and fluoride) illustrates the sensitivity of the methodology.

  11. Rapid Diamond Deposition on Ni and Co Coatings by Using Twin Acetylene/Oxygen Gas Welding Torches

    NASA Astrophysics Data System (ADS)

    Ando, Yasutaka; Noda, Yoshimasa; Adachi, Shin-ichiro

    2015-12-01

    Cermet coatings have been widely used because of their high hardness and excellent wear resistance even under high-temperature conditions. However, since cermet coatings include expensive materials such as WC, TiC, TiN and so on, low-cost hard particles as a dispersing agent need to be developed. In this study, in order to develop a low-cost diamond dispersion system for the creation of diamond/thermal sprayed metal hybrid coatings, diamond deposition on thermal sprayed Ni and Co coatings and Mo and Ni metal substrates by the combustion flame method using twin acetylene/oxygen gas welding torches was carried out. Consequently, even in cases of thermal sprayed Ni and Co coatings, diamond particles could be deposited within only 5 min. From these results, this technique is proved to have a high potential for rapid diamond deposition in order to create diamond/thermal sprayed metal hybrid coatings.

  12. Diamonds in detonation soot

    NASA Technical Reports Server (NTRS)

    Greiner, N. Roy; Phillips, Dave; Johnson, J. D.; Volk, Fred

    1990-01-01

    Diamonds 4 to 7 nm in diameter have been identified and partially isolated from soot formed in detonations of carbon-forming composite explosives. The morphology of the soot has been examined by transmission electron microscopy (TEM), and the identity of the diamond has been established by the electron diffraction pattern of the TEM samples and by the X-ray diffraction (XRD) pattern of the isolated solid. Graphite is also present in the form of ribbons of turbostatic structure with a thickness of 2 to 4 nm. A fraction, about 25 percent of the soot by weight, was recovered from the crude soot after oxidation of the graphite with fuming perchloric acid. This fraction showed a distinct XRD pattern of diamond and the diffuse band of amorphous carbon. The IR spectrum of these diamonds closely matches that of diamonds recovered from meteorites (Lewis et al., 1987), perhaps indicating similar surface properties after the oxidation. If these diamonds are produced in the detonation itself or during the initial expansion, they exhibit a phenomenal crystal growth rate (5 nm/0.00001 s equal 1.8 m/hr) in a medium with a very low hydrogen/carbon ratio. Because the diamonds will be carried along with the expanding gases, they will be accelerated to velocities approaching 8 km/s.

  13. Sex differences in Hadza dental wear patterns : a preliminary report.

    PubMed

    Berbesque, J Colette; Marlowe, Frank W; Pawn, Ian; Thompson, Peter; Johnson, Guy; Mabulla, Audax

    2012-09-01

    Among hunter-gatherers, the sharing of male and female foods is often assumed to result in virtually the same diet for males and females. Although food sharing is widespread among the hunting and gathering Hadza of Tanzania, women were observed eating significantly more tubers than men. This study investigates the relationship between patterns of dental wear, diet, and extramasticatory use of teeth among the Hadza. Casts of the upper dentitions were made from molds taken from 126 adults and scored according to the Murphy dental attrition scoring system. Females had significantly greater anterior occlusal wear than males when we controlled for age. Males exhibited greater asymmetry in wear, with greater wear on the left side in canines, first premolars, and first molars. We suggest that these sex differences in wear patterns reflect the differences seen in the diet, as well as in the use of teeth as tools.

  14. Ceramic wear in indentation and sliding

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1984-01-01

    The various wear mechanisms involved with single-crystal ceramic materials in indentation and in sliding contacts. Experiments simulating interfacial events have been conducted with hemispherical, conical and pyramidal indenters (riders). With spherical riders, under either abrasive or adhesive conditions, two types of fracture pits have been observed. First, spherical-shaped fracture pits and wear particles are found as a result of either indenting or sliding. These are shown to be due to a spherical-shaped fracture along the circular or spherical stress trajectories. Second, polyhedral fracture pits and debris, produced by anisotropic fracture, and also found both during indenting and sliding. These are primarily controlled by surface and subsurface cracking along cleavage planes. Several quantitative results have also been obtained from this work. For example, using a pyramidal diamond, crack length of Mn-Zn ferrite in the indentation process grows linearly with increasing normal load. Moreover, the critical load to fracture both in indentation and sliding is essentially isotropic and is found to be directly proportional to the indenter radius.

  15. Atomic-scale wear of amorphous hydrogenated carbon during intermittent contact: a combined study using experiment, simulation, and theory.

    PubMed

    Vahdat, Vahid; Ryan, Kathleen E; Keating, Pamela L; Jiang, Yijie; Adiga, Shashishekar P; Schall, J David; Turner, Kevin T; Harrison, Judith A; Carpick, Robert W

    2014-07-22

    In this study, we explore the wear behavior of amplitude modulation atomic force microscopy (AM-AFM, an intermittent-contact AFM mode) tips coated with a common type of diamond-like carbon, amorphous hydrogenated carbon (a-C:H), when scanned against an ultra-nanocrystalline diamond (UNCD) sample both experimentally and through molecular dynamics (MD) simulations. Finite element analysis is utilized in a unique way to create a representative geometry of the tip to be simulated in MD. To conduct consistent and quantitative experiments, we apply a protocol that involves determining the tip-sample interaction geometry, calculating the tip-sample force and normal contact stress over the course of the wear test, and precisely quantifying the wear volume using high-resolution transmission electron microscopy imaging. The results reveal gradual wear of a-C:H with no sign of fracture or plastic deformation. The wear rate of a-C:H is consistent with a reaction-rate-based wear theory, which predicts an exponential dependence of the rate of atom removal on the average normal contact stress. From this, kinetic parameters governing the wear process are estimated. MD simulations of an a-C:H tip, whose radius is comparable to the tip radii used in experiments, making contact with a UNCD sample multiple times exhibit an atomic-level removal process. The atomistic wear events observed in the simulations are correlated with under-coordinated atomic species at the contacting surfaces.

  16. Diamond-cBN alloy: A universal cutting material

    SciTech Connect

    Wang, Pei; He, Duanwei Kou, Zili; Li, Yong; Hu, Qiwei; Xu, Chao; Lei, Li; Wang, Qiming; Wang, Liping; Zhao, Yusheng; Xiong, Lun; Liu, Jing

    2015-09-07

    Diamond and cubic boron nitride (cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesis and characterization of transparent bulk diamond-cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond-cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. High-speed cutting tests on hardened steel and granite suggest that diamond-cBN alloy is indeed a universal cutting material.

  17. Diamond-cBN alloy: A universal cutting material

    NASA Astrophysics Data System (ADS)

    Wang, Pei; He, Duanwei; Wang, Liping; Kou, Zili; Li, Yong; Xiong, Lun; Hu, Qiwei; Xu, Chao; Lei, Li; Wang, Qiming; Liu, Jing; Zhao, Yusheng

    2015-09-01

    Diamond and cubic boron nitride (cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesis and characterization of transparent bulk diamond-cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond-cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. High-speed cutting tests on hardened steel and granite suggest that diamond-cBN alloy is indeed a universal cutting material.

  18. Employees Wearing Religious Attire

    ERIC Educational Resources Information Center

    Zirkel, Perry

    2004-01-01

    While adherents to many religions can be identified by distinctive clothing or accessories, the wearing of such garb by teachers is not necessarily related to evangelism in the classroom. The following case and the accompanying question-and-answer discussion illustrate the problem of the principal caught between the rock of First Amendment…

  19. Tribological properties of undoped and boron-doped nanocrystalline diamond films

    PubMed Central

    Liang, Qi; Stanishevsky, Andrei; Vohra, Yogesh K.

    2009-01-01

    Undoped and boron-doped nanocrystalline (NCD) diamond films were deposited on mirror polished Ti–6Al–4V substrates in a Microwave Plasma Assisted Chemical Vapor Deposition system. Sliding wear tests were conducted in ambient air with a nanotribometer. A systematic study of the tribological properties for both undoped and boron-doped NCD films were carried out. It was found for diamond/diamond sliding, coefficient of friction decreases with increasing normal loads. It was also found that the wear rate of boron-doped NCD films is about 10 times higher than that of undoped films. A wear rate of ~5.2×10−9 mm3/Nm was found for undoped NCD films. This value is comparable to the best known value of that of polished polycrystalline diamond films. Although no surface deformation, film delamination or micro-cracking were observed for undoped films, boron-doped NCD film undergoes a critical failure at a normal stress of 2.2 GPa, above which surface deformation is evident. Combined with high hardness and modulus, tunable conductivity and improved open air thermal stability, boron-doped nanocrystalline diamond film has tremendous potentials for applications such as Atomic Force Microscope probes, Micro-Electro-Mechanical System devices and biomedical sensors. PMID:19946362

  20. X-ray topographic study of diamonds: implications for the genetic nature of inclusions in diamond

    NASA Astrophysics Data System (ADS)

    Agrosì, Giovanna; Nestola, Fabrizio; Tempesta, Gioacchino; Bruno, Marco; Scandale, Eugenio; Harris, Jeff W.

    2014-05-01

    In recent years, several studies have focused on the growth conditions of the diamonds through the analysis of the mineral inclusions trapped in them (Howell, 2012 and references therein). Nevertheless, to obtain rigorous information about chemical and physical conditions of diamond formation, it is crucial to determine if the crystallization of the inclusions occurred before (protogenetic nature), during (syngenetic nature) or after (epigenetic nature) the growth of diamond (Wiggers de Vries et al., 2011). X-ray topography (XRDT) can be a helpful tool to verify the genetic nature of inclusions in diamond. This technique characterizes the extended defects and reconstructs the growth history of the samples (Agrosì et al., 2013 and references therein) and, consequently contributes to elucidation of the relationship between the inclusions and the host-diamond. With this aim a diamond from the Udachnaya kimberlite, Siberia, was investigated. The diamond crystal was the one previously studied by Nestola et al. (2011) who performed in-situ crystal structure refinement of the inclusions to obtain data about the formation pressure. The inclusions were iso-oriented olivines that did not show evident cracks and subsequently could not be considered epigenetic. Optical observations revealed an anomalous birefringence in the adjacent diamond and the inclusions had typical "diamond-imposed cubo-octahedral" shape for the largest olivine. The diffraction contrast study shows that the diamond exhibits significant deformation fields related to plastic post growth deformation. The crystallographic direction of strains was established applying the extinction criterion. Section topographs were taken to minimize the overlapping of the strain field associate with the different defects and revealed that no dislocations nucleated from the olivine inclusions. Generally, when a solid inclusion has been incorporated in the growing crystal, the associated volume distortion can be minimized by

  1. Fabrication of diamond shells

    DOEpatents

    Hamza, Alex V.; Biener, Juergen; Wild, Christoph; Woerner, Eckhard

    2016-11-01

    A novel method for fabricating diamond shells is introduced. The fabrication of such shells is a multi-step process, which involves diamond chemical vapor deposition on predetermined mandrels followed by polishing, microfabrication of holes, and removal of the mandrel by an etch process. The resultant shells of the present invention can be configured with a surface roughness at the nanometer level (e.g., on the order of down to about 10 nm RMS) on a mm length scale, and exhibit excellent hardness/strength, and good transparency in the both the infra-red and visible. Specifically, a novel process is disclosed herein, which allows coating of spherical substrates with optical-quality diamond films or nanocrystalline diamond films.

  2. Amorphous diamond films

    DOEpatents

    Falabella, S.

    1998-06-09

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  3. Diamond Ranch High School.

    ERIC Educational Resources Information Center

    Betsky, Aaron

    2000-01-01

    Highlights award-winning Diamond Ranch High School (California) that was designed and built on a steep site around Los Angeles considered unsatisfactory for building due to its unstable soils. Building organization is discussed, and photos are provided. (GR)

  4. Synthesis of diamonds

    NASA Technical Reports Server (NTRS)

    Estes, M. F.; Rasquin, J. R.

    1970-01-01

    Shock wave transmitted through a solid exponential horn generates heat and pressure to convert part of a charge of graphite to diamonds. The shock wave is generated in the apparatus by a complex of magnetic fields and eddy currents.

  5. California: Diamond Valley

    Atmospheric Science Data Center

    2014-05-15

    ... County is billed as the largest earthworks construction project in U.S. history. Construction began in 1995 and involved 31 million ... water storage capacity. In addition to routine water management, Diamond Valley Lake is designed to provide protection against ...

  6. PROCESS FOR COLORING DIAMONDS

    DOEpatents

    Dugdale, R.A.

    1960-07-19

    A process is given for coloring substantially colorless diamonds in the blue to blue-green range and comprises the steps of irradiating the colorless diamonds with electrons having an energy within the range 0.5 to 2 Mev to obtain an integrated electron flux of between 1 and 2 x 10/sup 18/ thc diamonds may be irradiated 1 hr when they take on a blue color with a slight green tint: After being heated at about 500 deg C for half an hour they become pure blue. Electrons within this energy range contam sufficient energy to displace the diamond atoms from their normal lattice sites into interstitial sites, thereby causing the color changes.

  7. Mechanics of interaction and atomic-scale wear of amplitude modulation atomic force microscopy probes.

    PubMed

    Vahdat, Vahid; Grierson, David S; Turner, Kevin T; Carpick, Robert W

    2013-04-23

    Wear is one of the main factors that hinders the performance of probes for atomic force microscopy (AFM), including for the widely used amplitude modulation (AM-AFM) mode. Unfortunately, a comprehensive scientific understanding of nanoscale wear is lacking. We have developed a protocol for conducting consistent and quantitative AM-AFM wear experiments. The protocol involves controlling the tip-sample interaction regime during AM-AFM scanning, determining the tip-sample contact geometry, calculating the peak repulsive force and normal stress over the course of the wear test, and quantifying the wear volume using high-resolution transmission electron microscopy imaging. The peak repulsive tip-sample interaction force is estimated from a closed-form equation accompanied by an effective tip radius measurement procedure, which combines transmission electron microscopy and blind tip reconstruction. The contact stress is estimated by applying Derjaguin-Müller-Toporov contact mechanics model and also numerically solving a general contact mechanics model recently developed for the adhesive contact of arbitrary axisymmetric punch shapes. We discuss the important role that the assumed tip shape geometry plays in calculating both the interaction forces and the contact stresses. Contact stresses are significantly affected by the tip geometry while the peak repulsive force is mainly determined by experimentally controlled parameters, specifically, the free oscillation amplitude and amplitude ratio. The applicability of this protocol is demonstrated experimentally by assessing the performance of diamond-like carbon-coated and silicon-nitride-coated silicon probes scanned over ultrananocrystalline diamond substrates in repulsive mode AM-AFM. There is no sign of fracture or plastic deformation in the case of diamond-like carbon; wear could be characterized as a gradual atom-by-atom process. In contrast, silicon nitride wears through removal of the cluster of atoms and plastic

  8. Wear Assessment of Conical Pick used in Coal Cutting Operation

    NASA Astrophysics Data System (ADS)

    Dewangan, Saurabh; Chattopadhyaya, Somnath; Hloch, Sergej

    2015-09-01

    Conical pick is a widely used tool for cutting coal in mines. It has a cemented carbide tip inserted in a steel body. Cemented carbide has been in use for many years for coal/rock cutting because it has the optimum combination of hardness, toughness and resistance against abrasive wear. As coal/rock is a heterogeneous substance, the cutting tool has to undergo various obstructions at the time of excavation that cause the tool to wear out. The cracks and fractures developing in the cemented carbide limit the life of the tool. For a long time, different wear mechanisms have been studied to develop improved grades of cemented carbide with high wear resistance properties. The research is still continuing. Moreover, due to the highly unpredictable nature of coal/rock, it is not easy to understand the wear mechanisms. In the present work, an attempt has been made to understand the wear mechanisms in four conical picks, which were used in a continuous miner machine for underground mining of coal. The wearing pattern of the conical pick indicates damage in its cemented carbide tip as well as the steel body. The worn out parts of the tools have been critically examined using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) point analysis. Mainly four types of wear mechanisms, namely, coal/rock intermixing, plastic deformation, rock channel formation and crushing and cracking, have been detected. The presence of coal/rock material and their respective concentrations in the selected area of worn out surface were observed using the spectra generated by EDX analysis.

  9. High-mobility diamond

    NASA Astrophysics Data System (ADS)

    Landstrass, Maurice I.

    1994-04-01

    Recent improvements in the CVD diamond deposition process have made possible the fabrication of diamond photoconductive diodes with carrier mobility and lifetime exceeding the values typical of natural gemstones. One of the more surprising recent results is that the best room-temperature carrier properties have been measured on polycrystalline diamond films. The combined electron- hole mobility, as measured by transient photoconductivity at low carrier densities, is 4000 square centimeters per volt per second at electric field of 200 volts per centimeter and is comparable to that of the best single-crystal IIa natural diamonds. Carrier lifetimes measured under the same conditions are 150 picoseconds for the CVD diamond films. The collection distance within the diamond films, at the highest applied fields, is comparable to the average film grain size, indicative of little or no carrier scattering at grain boundaries. A comparison of SIMS measurements with electrical results suggest that impurity incorporation in the near grain boundary regions are responsible for controlling the carrier mobility.

  10. Effect of Surface Chemistry on the Mechanisms and Governing Laws of Friction and Wear.

    PubMed

    Dai, Ling; Sorkin, Viacheslav; Zhang, Yong-Wei

    2016-04-01

    Recent studies have shown that interface chemistry, that is, the formation and breaking of chemical bonds across contacting interfaces, is closely related to the wear and friction behavior at the nanoscale. In reality, the dangling bond density (DBD) at contacting surfaces can vary greatly. Currently, it remains unclear how friction and wear mechanisms depend on DBDs and whether the Archard's law for wear and Amonton's law for friction are still applicable for contacting surfaces with different DBDs. In this work, we address these issues by studying the wear and friction behavior between two sliding diamond-like carbon surfaces by controlling DBDs via hydrogenation using molecular dynamics simulations. It is found that the chemical bond breaking and remaking across the contacting interface play the key role in determining the friction and wear behavior. During the sliding, a higher DBD leads to more chemical bond formations across the interface, causing stronger wear via either atom or cluster detachments. With the same DBD, a mechanism transition from an atom-by-atom to cluster detachments is observed by increasing the normal load. Remarkably, a fully saturated surface can exhibit a wearless friction. We further show that after necessary modifications, the Archard's law for wear and the Amonton's law for friction may be applicable at the nanoscale. The present work reveals insights into the effect of interface chemistry on the friction and wear, and it provides guidelines for effective antiwear design.

  11. Low-Wear Ball-Bearing Separator

    NASA Technical Reports Server (NTRS)

    Hawkinson, Elden L.

    1991-01-01

    Proposed ball-bearing separator for use in cryogenic pump stronger and more resistant to wear. Consists of molded plastic-and-metal composite ring imbued with solid lubricant and containing embedded metal ring. Obtains combination of strength and lubricity. Before molding and machining, ring includes tooling portion for handling and indexing. Molded composite blend of PTFE and fluorinated ethylene/propylene (FEP) filled with brass and bronze powder and molybdenum disulfide powder.

  12. Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings.

    PubMed

    Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

    2016-01-01

    Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

  13. Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

    PubMed Central

    Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

    2016-01-01

    Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings. PMID:26924136

  14. Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

    2016-02-01

    Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

  15. Two- and three-dimensional ultrananocrystalline diamond (UNCD) structures for a high resolution diamond-based MEMS technology.

    SciTech Connect

    Auciello, O.; Krauss, A. R.; Gruen, D. M.; Busmann, H. G.; Meyer, E. M.; Tucek, J.; Sumant, A.; Jayatissa, A.; Moldovan, N.; Mancini, D. C.; Gardos, M. N.

    2000-01-17

    Silicon is currently the most commonly used material for the fabrication of microelectromechanical systems (MEMS). However, silicon-based MEMS will not be suitable for long-endurance devices involving components rotating at high speed, where friction and wear need to be minimized, components such as 2-D cantilevers that may be subjected to very large flexural displacements, where stiction is a problem, or components that will be exposed to corrosive environments. The mechanical, thermal, chemical, and tribological properties of diamond make it an ideal material for the fabrication of long-endurance MEMS components. Cost-effective fabrication of these components could in principle be achieved by coating Si with diamond films and using conventional lithographic patterning methods in conjunction with e. g. sacrificial Ti or SiO{sub 2} layers. However, diamond coatings grown by conventional chemical vapor deposition (CVD) methods exhibit a coarse-grained structure that prevents high-resolution patterning, or a fine-grained microstructure with a significant amount of intergranular non-diamond carbon. The authors demonstrate here the fabrication of 2-D and 3-D phase-pure ultrananocrystalline diamond (UNCD) MEMS components by coating Si with UNCD films, coupled with lithographic patterning methods involving sacrificial release layers. UNCD films are grown by microwave plasma CVD using C{sub 60}-Ar or CH{sub 4}-Ar gas mixtures, which result in films that have 3--5 nm grain size, are 10--20 times smoother than conventionally grown diamond films, are extremely resistant to corrosive environments, and are predicted to have a brittle fracture strength similar to that of single crystal diamond.

  16. Cryotribology of diamond and graphite

    SciTech Connect

    Iwasa, Yukikazu; Ashaboglu, A.F.; Rabinowicz, E.R.

    1996-12-31

    An experimental study was carried out on the tribological behavior of materials of interest in cryogenic applications, focusing on diamond and graphite. Both natural diamond (referred in the text as diamond) and chemical-vapor-deposition (CVD) diamond (CVD-diamond) were used. The experiment was carried out using a pin-on-disk tribometer capable of operating at cryogenic temperatures, from 4.2 to 293 K. Two basic scenarios of testing were used: (1) frictional coefficient ({mu}) vs velocity (v) characteristics at constant temperatures; (2) {mu} vs temperature (T) behavior at fixed sliding speeds. For diamond/CVD-diamond, graphite/CVD-diamond, stainless steel/CVD-diamond pairs, {mu}`s are virtually velocity independent. For each of diamond/graphite, alumina/graphite, and graphite/graphite pairs, the {partial_derivative}{mu}/{partial_derivative}v characteristic is favorable, i.e., positive. For diamond/CVD-diamond and graphite/CVD-diamond pairs, {mu}`s are nearly temperature independent between in the range 77 - 293 K. Each {mu} vs T plot for pin materials sliding on graphite disks has a peak at a temperature in the range 100 - 200 K.

  17. Diamond Electronic Devices

    NASA Astrophysics Data System (ADS)

    Isberg, J.

    2010-11-01

    For high-power and high-voltage applications, silicon is by far the dominant semiconductor material. However, silicon has many limitations, e.g. a relatively low thermal conductivity, electric breakdown occurs at relatively low fields and the bandgap is 1.1 eV which effectively limits operation to temperatures below 175° C. Wide-bandgap materials, such as silicon carbide (SiC), gallium nitride (GaN) and diamond offer the potential to overcome both the temperature and power handling limitations of silicon. Diamond is the most extreme in this class of materials. By the fundamental material properties alone, diamond offers the largest benefits as a semiconductor material for power electronic applications. On the other hand, diamond has a problem with a large carrier activation energy of available dopants which necessitates specialised device concepts to allow room temperature (RT) operation. In addition, the role of common defects on the charge transport properties of diamond is poorly understood. Notwithstanding this, many proof-of-principle two-terminal and three-terminal devices have been made and tested. Two-terminal electronic diamond devices described in the literature include: p-n diodes, p-i-n diodes, various types of radiation detectors, Schottky diodes and photoconductive or electron beam triggered switches. Three terminal devices include e.g. MISFETs and JFETs. However, the development of diamond devices poses great challenges for the future. A particularly interesting way to overcome the doping problem, for which there has been some recent progress, is to make so-called delta doped (or pulse-doped) devices. Such devices utilise very thin (˜1 nm) doped layers in order to achieve high RT activation.

  18. Friction and Wear

    NASA Technical Reports Server (NTRS)

    Pomey, Jacques

    1952-01-01

    From the practical point of view, this analysis shows that each problem of friction or wear requires its particular solution. There is no universal solution; one or other of the factors predominates and defines the choice of the solution. In certain cases, copper alloys of great thermal conductivity are preferred; in others, plastics abundantly supplied with water. Sometimes, soft antifriction metals are desirable to distribute the load; at other times, hard metals with high resistance to abrasion or heat.

  19. Rolling-contact and wear resistance of hard coatings on bearing-steel substrates

    NASA Astrophysics Data System (ADS)

    Erdemir, A.

    1992-02-01

    Ever-increasing needs for high-performance ball- and roller-bearing components that can endure extreme applications have led to a growing interest in hard coatings for improved fatigue life and wear resistance. In particular, hard TiN and TiC coatings and, quite recently, diamond like carbon films have attracted much attention from manufacturers that produce bearing systems for both rolling- and sliding-contact applications. This paper presents an overview that highlights recent incremental progress in achieving improved fatigue and wear resistance in bearing steels through the use of hard coatings. Effects of coating adhesion, thickness, and morphology on fatigue and wear resistance of hard coatings are discussed in detail. Specific references are made to a few mechanistic models that correlate coating thickness and adhesion to improved fatigue life and wear resistance.

  20. Friction Properties of Polished Cvd Diamond Films Sliding against Different Metals

    NASA Astrophysics Data System (ADS)

    Lin, Zichao; Sun, Fanghong; Shen, Bin

    2016-11-01

    Owing to their excellent mechanical and tribological properties, like the well-known extreme hardness, low coefficient of friction and high chemical inertness, chemical vapor deposition (CVD) diamond films have found applications as a hard coating for drawing dies. The surface roughness of the diamond films is one of the most important attributes to the drawing dies. In this paper, the effects of different surface roughnesses on the friction properties of diamond films have been experimentally studied. Diamond films were fabricated using hot filament CVD. The WC-Co (Co 6wt.%) drawing dies were used as substrates. A gas mixture of acetone and hydrogen gas was used as the feedstock gas. The CVD diamond films were polished using mechanical polishing. Polished diamond films with three different surface roughnesses, as well as the unpolished diamond film, were fabricated in order to study the tribological performance between the CVD diamond films and different metals with oil lubrication. The unpolished and polished CVD diamond films are characterized with scanning electron microscope (SEM), atomic force microscope (AFM), surface profilometer, Raman spectrum and X-ray diffraction (XRD). The friction examinations were carried out by using a ball-on-plate type reciprocating friction tester. Low carbide steel, stainless steel, copper and aluminum materials were used as counterpart balls. Based on this study, the results presented the friction coefficients between the polished CVD films and different metals. The friction tests demonstrate that the smooth surface finish of CVD diamond films is beneficial for reducing their friction coefficients. The diamond films exhibit low friction coefficients when slid against the stainless steel balls and low carbide steel ball, lower than that slid against copper ball and aluminum ball, attributed to the higher ductility of copper and aluminum causing larger amount of wear debris adhering to the sliding interface and higher adhesive

  1. Corrosive wear principles

    SciTech Connect

    Schumacher, W.J.

    1993-12-31

    The dual effects of corrosion and wear operate together in such industries as paper and pulp, coal handling, mining, and sugar beet extraction. There is a synergistic effect that causes far greater wastage to carbon steels, alloy steels, and even much more abrasion resistant cast irons. Several laboratory and in situ studies have been conducted to better understand the contributions of corrosion and wear to the wastage process. The environmental conditions are usually set by the process. However, there are a few instances where inhibitors as sodium nitrite, sodium chromate, and sodium metasilicate have been successfully used to reduce metal wastage of carbon steels. Hardness has been found to be an unreliable guide to performance under wet sliding conditions. Heat treated alloy steels and cast irons are inferior to stainless steels. Even distilled water is too severe a corrodent for steels. While the austenitic stainlesses perform the best, cold rolling to increase hardness does not further improve their performance. The surface roughness of stainless steels gets smoother during corrosive wear testing while it gets rougher for the alloy steels. This observation substantiated the reputation of improved slideability for stainless alloys over alloy steels.

  2. Wear and Tear - Mechanical

    NASA Technical Reports Server (NTRS)

    Swanson, Theodore

    2008-01-01

    The focus of this chapter is on the long term wear and tear, or aging, of the mechanical subsystem of a spacecraft. The mechanical subsystem is herein considered to be the primary support structure (as in a skeleton or exoskeleton) upon which all other spacecraft systems rest, and the associated mechanisms. Mechanisms are devices which have some component that moves at least once, in response to some type of passive or active control system. For the structure, aging may proceed as a gradual degradation of mechanical properties and/or function, possibly leading to complete structural failure over an extended period of time. However, over the 50 years of the Space Age such failures appear to be unusual. In contrast, failures for mechanisms are much more frequent and may have a very serious effect on mission performance. Just as on Earth, all moving devices are subject to normal (and possibly accelerated) degradation from mechanical wear due to loss or breakdown of lubricant, misalignment, temperature cycling effects, improper design/selection of materials, fatigue, and a variety of other effects. In space, such environmental factors as severe temperature swings (possibly 100's of degrees C while going in and out of direct solar exposure), hard vacuum, micrometeoroids, wear from operation in a dusty or contaminated environment, and materials degradation from radiation can be much worse. In addition, there are some ground handling issues such as humidity, long term storage, and ground transport which may be of concern. This chapter addresses the elements of the mechanical subsystem subject to wear, and identifies possible causes. The potential impact of such degradation is addressed, albeit with the recognition that the impact of such wear often depends on when it occurs and on what specific components. Most structural elements of the mechanical system typically are conservatively designed (often to a safety factor of greater than approximately 1.25 on yield for

  3. The Diamond Makers

    NASA Astrophysics Data System (ADS)

    Hazen, Robert M.

    1999-08-01

    Since time immemorial, we have treasured diamonds for their exquisite beauty and unrivaled hardness. Yet, most of the earth's diamonds lie deep underground and totally unaccessible to us--if only we knew how to fabricate them! In The Diamond Makers Robert Hazen vividly recounts the very human desire to exceed nature and create a synthetic diamond. Spanning centuries of ground-breaking science, instances of bitter rivalry, cases of outright fraud and self-delusion, Hazen blends drama and science to reveal the extraordinary technological advances and devastating failures of the diamond industry. Along the way, readers will be introduced to the brilliant, often eccentric and controversial, pioneers of high-pressure research who have harnessed crushing pressures and scorching temperatures to transform almost any carbon-rich material, from road tar to peanut butter, into the most prized of all gems. Robert M. Hazen is the author of fifteen books, including the bestseller, Science Matters: Achieving Scientific Literacy, which he wrote with James Trefil. Dr. Hazen has won numerous awards for his research and scientific writing.

  4. PREFACE: Science's gem: diamond science 2009 Science's gem: diamond science 2009

    NASA Astrophysics Data System (ADS)

    Mainwood, Alison; Newton, Mark E.; Stoneham, Marshall

    2009-09-01

    devices, exploiting excellent quality boron doped p-type material, can be designed [3]. Electrical contacts can be tricky to fabricate, but progress is being made here [3, 27]. Diamond is perceived as unacceptably expensive, but for a high-quality device for an exceptional environment, this is not a problem. Carbon-based electronic materials are strikingly diverse. They include diamond, graphite, nanotubes and buckyball structures, amorphous carbons, and nanodiamond. Add hydrogen and one has a range of diamond-like carbons and the wealth of organics. Such carbon-based materials include small molecules and polymers: impressive insulators, semiconducting and conducting polymers, switchable forms, superconducting and magnetic forms, and some with the highest electrical conductivities of any material. Diamond-like carbons can have controllable mechanical properties from the viscoelastic to the highly rigid. Photochemistry brings opportunities for novel processing methods. Even water-based processing may sometimes be possible (alas, not for diamond), and additional tools like self-organisation of organic molecules on surfaces have been demonstrated. The best carbons have impressive, sometimes supreme, performances, including the mobility and optical properties of diamond, spin-conserving transport in carbon nanotubes, and electron emission. For almost all measures of performance, there is some carbon-based material that performs better than silicon. Might hybrid carbon-based materials be more successful even than silicon [28]? Should we think less about 'diamond' and more about the integration of diamond as one component of carbon electronics? Device fabrication needs lithography optics and resists, and processing at the anticipated smaller scales may well exploit new electronic excitation methods. Alternative dielectrics and interconnect materials introduce new compatibility issues, and there are further varied constraints from displays, spintronic components, electron

  5. Diamond-Cutter Drill Bits

    SciTech Connect

    1995-11-01

    Geothermal Energy Program Office of Geothermal and Wind Technologies Diamond-Cutter Drill Bits Diamond-cutter drill bits cut through tough rock quicker, reducing the cost of drilling for energy resources The U.S. Department of Energy (DOE) contributed markedly to the geothermal, oil, and gas industries through the development of the advanced polycrystalline diamond compact (PDC) drill bit. Introduced in the 1970s by General Electric Company (GE), the PDC bit uses thin, diamond layers bonded to t

  6. Diamond collecting in northern Colorado.

    USGS Publications Warehouse

    Collins, D.S.

    1982-01-01

    The discovery of numerous diamond-bearing kimberlite diatremes in the N Front Range of Colorado and Wyoming is of both scientific and economic interest. Species recovered from heavy-mineral concentrates include Cr-diopside, spinel, Mg-ilmenite, pyrope and diamond. A nodule tentatively identified as a graphite-diamond eclogite was also found. -G.W.R.

  7. Making Diamond in the Laboratory

    ERIC Educational Resources Information Center

    Strong, Herbert

    1975-01-01

    Discusses the graphite to diamond transformation and a phase diagram for carbon. Describes high temperature-higher pressure experimental apparatus and growth of diamonds from seed crystals. Reviews properties of the diamond which suggest uses for the synthetic product. Illustrations with text. (GH)

  8. Friction coefficient of diamond under conditions compatible with microelectromechanical systems applications

    NASA Astrophysics Data System (ADS)

    Gobet, J.; Volpe, P.-N.; Dubois, M.-A.

    2016-03-01

    Because of its good tribological properties, diamond has been suggested to solve the known reliability issues in silicon MEMS components submitted to frictional contacts. An evaluation of self-mating diamond friction under a low load, representative of a number of MEMS applications, was undertaken. Results have shown that initial friction coefficients of 0.02-0.05 can be achieved, as reported in the literature. However, continuation of the test for an extended period of time invariably led to a strong increase of the friction coefficient. This phenomenon has been observed with different types of diamonds (mono-, micro-, or nano-crystalline), suggesting that it is a general behavior for diamond under our experimental conditions. A micro structuration of the surface prevented this phenomenon by limiting the increase of the contact area resulting from wear.

  9. Fast and sensitive protein alignment using DIAMOND.

    PubMed

    Buchfink, Benjamin; Xie, Chao; Huson, Daniel H

    2015-01-01

    The alignment of sequencing reads against a protein reference database is a major computational bottleneck in metagenomics and data-intensive evolutionary projects. Although recent tools offer improved performance over the gold standard BLASTX, they exhibit only a modest speedup or low sensitivity. We introduce DIAMOND, an open-source algorithm based on double indexing that is 20,000 times faster than BLASTX on short reads and has a similar degree of sensitivity.

  10. Conditioning method development for 3M Trizact diamond tile fixed abrasives used in the finishing of brittle substrates; Technical Digest

    NASA Astrophysics Data System (ADS)

    Fletcher, Tim; Gobena, Feben T.; Romero, Vince; Sventek, Bruce; Schoenhofen, Walter

    2005-05-01

    Results of a series of single sided lapping experiments designed to develop appropriate conditioning methods for 3M Trizact Diamond Tile fixed abrasives are reported. Trizact™ Diamond Tile is a structured fixed abrasive lapping technology developed by 3M. The Trizact™ Diamond Tile structured abrasive pad consists of an organic (polymeric binder)-inorganic (abrasive mineral, i.e., diamond) composite that is used with a water-based coolant. The effect of platen and conditioner speed on pad wear will be explored for a roller yoke single-side lapping machine. Pad break-in conditioning was studied in detail for a 6 micron Trizact™ Diamond Tile abrasive used to lap soda-lime glass.

  11. Diamond Measuring Machine

    SciTech Connect

    Krstulic, J.F.

    2000-01-27

    The fundamental goal of this project was to develop additional capabilities to the diamond measuring prototype, work out technical difficulties associated with the original device, and perform automated measurements which are accurate and repeatable. For this project, FM and T was responsible for the overall system design, edge extraction, and defect extraction and identification. AccuGem provided a lab and computer equipment in Lawrence, 3D modeling, industry expertise, and sets of diamonds for testing. The system executive software which controls stone positioning, lighting, focusing, report generation, and data acquisition was written in Microsoft Visual Basic 6, while data analysis and modeling were compiled in C/C++ DLLs. All scanning parameters and extracted data are stored in a central database and available for automated analysis and reporting. The Phase 1 study showed that data can be extracted and measured from diamond scans, but most of the information had to be manually extracted. In this Phase 2 project, all data required for geometric modeling and defect identification were automatically extracted and passed to a 3D modeling module for analysis. Algorithms were developed which automatically adjusted both light levels and stone focus positioning for each diamond-under-test. After a diamond is analyzed and measurements are completed, a report is printed for the customer which shows carat weight, summarizes stone geometry information, lists defects and their size, displays a picture of the diamond, and shows a plot of defects on a top view drawing of the stone. Initial emphasis of defect extraction was on identification of feathers, pinpoints, and crystals. Defects were plotted color-coded by industry standards for inclusions (red), blemishes (green), and unknown defects (blue). Diamonds with a wide variety of cut quality, size, and number of defects were tested in the machine. Edge extraction, defect extraction, and modeling code were tested for

  12. Process for making diamonds

    NASA Technical Reports Server (NTRS)

    Rasquin, J. R.; Estes, M. F. (Inventor)

    1973-01-01

    A description is given of a device and process for making industrial diamonds. The device is composed of an exponential horn tapering from a large end to a small end, with a copper plate against the large end. A magnetic hammer abuts the copper plate. The copper plate and magnetic hammer function together to create a shock wave at the large end of the horn. As the wave propagates to the small end, the extreme pressure and temperature caused by the wave transforms the graphite, present in an anvil pocket at the small end, into diamonds.

  13. Dosimetry with diamond detectors

    NASA Astrophysics Data System (ADS)

    Gervino, G.; Marino, C.; Silvestri, F.; Lavagno, A.; Truc, F.

    2010-05-01

    In this paper we present the dosimetry analysis in terms of stability and repeatability of the signal and dose rate dependence of a synthetic single crystal diamond grown by Chemical Vapor Deposition (CVD) technique. The measurements carried out by 5 MeV X-ray photons beam show very promising results, even if the dose rate detector response points out that the charge trapping centers distribution is not uniform inside the crystal volume. This handicap that affects the detectors performances, must be ascribed to the growing process. Synthetic single crystal diamonds could be a valuable alternative to air ionization chambers for quality beam control and for intensity modulated radiation therapy beams dosimetry.

  14. Cosmogenic Helium In Alluvial Diamonds From Namaqualand, South Africa

    NASA Astrophysics Data System (ADS)

    Burgess, R.; Harris, J. W.

    2005-12-01

    The interpretation of He in diamonds is not straightforward, potential sources include trapped mantle-derived He, radiogenic 4He, and 3He produced in situ by cosmic-ray spallation. The presence of cosmogenic 3He is manifested by high 3He/4He values and ratios of >200 Ra have been measured. 3He contents can be used to distinguish pipe from alluvial diamonds and the time interval that they have been involved in the sedimentary cycle, i.e. their surface exposure history. This is important information for locating the source of alluvial diamonds, understanding their transport histories and may provide a useful tool for diamond exploration. In this study we are analysing the He composition of ten alluvial diamonds from the Koignass-Namaqualand area along the south-west coast of South Africa and Namibia. Diamonds are currently mined at a depth of 100m below the surface from deposits of gravel beaches and river channels. Helium is extracted from the diamonds using a newly developed high temperature filament furnace having a blank approximately 200x lower than conventional resistance furnaces. The low blank of this system means it is possible to extract He by stepwise heating of diamonds weighing 0.05 g. Helium isotopes were analysed using a mass spectrometer with a 3He detection limit of 2,000,000 atoms equivalent to about 20 ka of surface exposure. Results from one diamond from Namaqualand illustrate the range of data obtained so far. This diamond was analysed using eight temperature steps and shows an overall increase in 3He/4He value with temperature from 8.8 x 10-6 to 2.6 x 10-2, the latter being only 10x lower than the pure spallogenic ratio. The cosmogenic 3He content is estimated at 73.5 x 10-12 cm3/g which is at the upper end of the range determined previously in alluvial diamonds from west African sources. Assuming a sea level 3He production rate at 30°S, then the 3He content of this diamond is equivalent to 16 Ma of surface exposure. Most of this exposure is

  15. Fluidized bed deposition of diamond

    DOEpatents

    Laia, Jr., Joseph R.; Carroll, David W.; Trkula, Mitchell; Anderson, Wallace E.; Valone, Steven M.

    1998-01-01

    A process for coating a substrate with diamond or diamond-like material including maintaining a substrate within a bed of particles capable of being fluidized, the particles having substantially uniform dimensions and the substrate characterized as having different dimensions than the bed particles, fluidizing the bed of particles, and depositing a coating of diamond or diamond-like material upon the substrate by chemical vapor deposition of a carbon-containing precursor gas mixture, the precursor gas mixture introduced into the fluidized bed under conditions resulting in excitation mechanisms sufficient to form the diamond coating.

  16. Wear mechanism based on adhesion

    NASA Technical Reports Server (NTRS)

    Yamamoto, T.; Buckley, D. H.

    1982-01-01

    Various concepts concerning wear mechanisms and deformation behavior observed in the sliding wear track are surveyed. The mechanisms for wear fragment formation is discussed on the basis of adhesion. The wear process under unlubricated sliding conditions is explained in relation to the concept of adhesion at the interface during the sliding process. The mechanism for tearing away the surface layer from the contact area and forming the sliding track contour is explained by assuming the simplified process of material removal based on the adhesion theory.

  17. Elucidation of wear mechanisms by ferrographic analysis

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.

    1981-01-01

    The use of ferrographic analysis in conjunction with light and scanning electron microscopy is described for the elucidation of wear mechanisms taking place in operating equipment. Example of adhesive wear, abrasive wear, corrosive wear, rolling element fatigue, lubricant breakdown, and other wear modes are illustrated. In addition, the use of magnetic solutions to precipitate nonmagnetic debris from aqueous and nonaqueous fluids is described.

  18. Evaluating the accuracy of wear formulae for acetabular cup liners.

    PubMed

    Wu, James Shih-Shyn; Hsu, Shu-Ling; Chen, Jian-Horng

    2010-02-01

    This study proposes two methods for exploring the wear volume of a worn liner. The first method is a numerical method, in which SolidWorks software is used to create models of the worn out regions of liners at various wear directions and depths. The second method is an experimental one, in which a machining center is used to mill polyoxymethylene to manufacture worn and unworn liner models, then the volumes of the models are measured. The results show that the SolidWorks software is a good tool for presenting the wear pattern and volume of a worn liner. The formula provided by Ilchmann is the most suitable for computing liner volume loss, but is not accurate enough. This study suggests that a more accurate wear formula is required. This is crucial for accurate evaluation of the performance of hip components implanted in patients, as well as for designing new hip components.

  19. Natural occurrence of pure nano-polycrystalline diamond from impact crater.

    PubMed

    Ohfuji, Hiroaki; Irifune, Tetsuo; Litasov, Konstantin D; Yamashita, Tomoharu; Isobe, Futoshi; Afanasiev, Valentin P; Pokhilenko, Nikolai P

    2015-01-01

    Consolidated bodies of polycrystalline diamond with grain sizes less than 100 nm, nano-polycrystalline diamond (NPD), has been experimentally produced by direct conversion of graphite at high pressure and high temperature. NPD has superior hardness, toughness and wear resistance to single-crystalline diamonds because of its peculiar nano-textures, and has been successfully used for industrial and scientific applications. Such sintered nanodiamonds have, however, not been found in natural mantle diamonds. Here we identified natural pure NPD, which was produced by a large meteoritic impact about 35 Ma ago in Russia. The impact diamonds consist of well-sintered equigranular nanocrystals (5-50 nm), similar to synthetic NPD, but with distinct [111] preferred orientation. They formed through the martensitic transformation from single-crystal graphite. Stress-induced local fragmentation of the source graphite and subsequent rapid transformation to diamond in the limited time scale result in multiple diamond nucleation and suppression of the overall grain growth, producing the unique nanocrystalline texture of natural NPD. A huge amount of natural NPD is expected to be present in the Popigai crater, which is potentially important for applications as novel ultra-hard material. PMID:26424384

  20. Natural occurrence of pure nano-polycrystalline diamond from impact crater

    PubMed Central

    Ohfuji, Hiroaki; Irifune, Tetsuo; Litasov, Konstantin D.; Yamashita, Tomoharu; Isobe, Futoshi; Afanasiev, Valentin P.; Pokhilenko, Nikolai P.

    2015-01-01

    Consolidated bodies of polycrystalline diamond with grain sizes less than 100 nm, nano-polycrystalline diamond (NPD), has been experimentally produced by direct conversion of graphite at high pressure and high temperature. NPD has superior hardness, toughness and wear resistance to single-crystalline diamonds because of its peculiar nano-textures, and has been successfully used for industrial and scientific applications. Such sintered nanodiamonds have, however, not been found in natural mantle diamonds. Here we identified natural pure NPD, which was produced by a large meteoritic impact about 35 Ma ago in Russia. The impact diamonds consist of well-sintered equigranular nanocrystals (5–50 nm), similar to synthetic NPD, but with distinct [111] preferred orientation. They formed through the martensitic transformation from single-crystal graphite. Stress-induced local fragmentation of the source graphite and subsequent rapid transformation to diamond in the limited time scale result in multiple diamond nucleation and suppression of the overall grain growth, producing the unique nanocrystalline texture of natural NPD. A huge amount of natural NPD is expected to be present in the Popigai crater, which is potentially important for applications as novel ultra-hard material. PMID:26424384

  1. Natural occurrence of pure nano-polycrystalline diamond from impact crater.

    PubMed

    Ohfuji, Hiroaki; Irifune, Tetsuo; Litasov, Konstantin D; Yamashita, Tomoharu; Isobe, Futoshi; Afanasiev, Valentin P; Pokhilenko, Nikolai P

    2015-10-01

    Consolidated bodies of polycrystalline diamond with grain sizes less than 100 nm, nano-polycrystalline diamond (NPD), has been experimentally produced by direct conversion of graphite at high pressure and high temperature. NPD has superior hardness, toughness and wear resistance to single-crystalline diamonds because of its peculiar nano-textures, and has been successfully used for industrial and scientific applications. Such sintered nanodiamonds have, however, not been found in natural mantle diamonds. Here we identified natural pure NPD, which was produced by a large meteoritic impact about 35 Ma ago in Russia. The impact diamonds consist of well-sintered equigranular nanocrystals (5-50 nm), similar to synthetic NPD, but with distinct [111] preferred orientation. They formed through the martensitic transformation from single-crystal graphite. Stress-induced local fragmentation of the source graphite and subsequent rapid transformation to diamond in the limited time scale result in multiple diamond nucleation and suppression of the overall grain growth, producing the unique nanocrystalline texture of natural NPD. A huge amount of natural NPD is expected to be present in the Popigai crater, which is potentially important for applications as novel ultra-hard material.

  2. Microstructure and mechanical properties of diamond films on titanium-aluminum-vanadium alloy

    NASA Astrophysics Data System (ADS)

    Catledge, Shane Aaron

    The primary focus of this dissertation is the investigation of the processing-structure-property relationships of diamond films deposited on Ti-6Al-4V alloy by microwave plasma chemical vapor deposition (MPCVD). By depositing a well-adhered protective layer of diamond on an alloy component, its hardness, wear-resistance, performance, and overall lifetime could be significantly increased. However, due to the large thermal expansion mismatch between the diamond film and metal (and the corresponding residual stress induced in the film), film adhesion is typically unsatisfactory and often results in immediate delamination after processing. Therefore, it is a major goal of this research to improve adhesion of the diamond film to the alloy substrate. Through the use of innovative processing techniques involving MPCVD deposition conditions and methane (CH4), nitrogen (N2), and hydrogen (H2) chemistry, we have achieved diamond films which consistently adhere to the alloy substrate. In addition, we have discovered that, with the appropriate choice of deposition conditions, the film structure can be tailored to range from highly crystalline, well-faceted diamond to nanocrystalline diamond with extremely low surface roughness (as low as 27 nm). The relationship between processing and structure was studied using in-situ optical emission spectroscopy, micro-Raman spectroscopy, surface profilometry, glancing-angle x-ray diffraction, and scanning electron microscopy. We observe that when nitrogen is added to the H2/CH4 feedgas mixture, a carbon-nitrogen (CN) emission band arises and its relative abundance to the carbon dimer (C2) gas species is shown to have a pronounced influence on the diamond film structure. By appropriate choice of deposition chemistry and conditions, we can tailor the diamond film structure and its corresponding properties. The mechanical properties of interest in this thesis are those relating to the integrity of the film/substrate interface, as well as the

  3. Carbonado: natural polycrystalline diamond.

    PubMed

    Trueb, L F; De Wys, E C

    1969-08-22

    Carbonados are porous aggregates of mostly xenomorphic diamond crystallites ranging in diameter from a fraction of a micron to over 20 microns. Crystalline inclusions (up to 3 percent) occur in the pores of the crystallites and consist mainly of orthoclase and small amounts of other igneous, metamorphic, and secondary minerals. PMID:17742270

  4. DIAMOND AMPLIFIED PHOTOCATHODES.

    SciTech Connect

    SMEDLEY,J.; BEN-ZVI, I.; BOHON, J.; CHANG, X.; GROVER, R.; ISAKOVIC, A.; RAO, T.; WU, Q.

    2007-11-26

    High-average-current linear electron accelerators require photoinjectors capable of delivering tens to hundreds of mA average current, with peak currents of hundreds of amps. Standard photocathodes face significant challenges in meeting these requirements, and often have short operational lifetimes in an accelerator environment. We report on recent progress toward development of secondary emission amplifiers for photocathodes, which are intended to increase the achievable average current while protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic (few keV) primary electrons into hundreds of electron-hole pairs via secondary electron emission. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen-terminated surface with negative electron affinity (NEA). Secondary emission gain of over 200 has been achieved. Two methods of patterning diamond, laser ablation and reactive-ion etching (RIE), are being developed to produce the required geometry. A variety of diagnostic techniques, including FTIR, SEM and AFM, have been used to characterize the diamonds.

  5. CVD diamond - fundamental phenomena

    SciTech Connect

    Yarbrough, W.A.

    1993-01-01

    This compilation of figures and diagrams addresses the basic physical processes involved in the chemical vapor deposition of diamond. Different methods of deposition are illustrated. For each method, observations are made of the prominent advantages and disadvantages of the technique. Chemical mechanisms of nucleation are introduced.

  6. Development of ultrananocrystalline diamond (UNCD) coatings for multipurpose mechanical pump seals.

    SciTech Connect

    Kovalchenko, A. M.; Elam, J. W.; Erdemir, A.; Carlisle, J. A.; Auciello, O.; Libera, J. A.; Pellin, M. J.; Gruen, D. M.; Hryn, J. N.

    2011-01-01

    The reliability and performance of silicon carbide (SiC) shaft seals on multipurpose mechanical pumps are improved by applying a protective coating of ultrananocrystalline diamond (UNCD). UNCD exhibits extreme hardness (97 GPa), low friction (0.1 in air) and outstanding chemical resistance. Consequently, the application of UNCD coatings to multipurpose mechanical pump seals can reduce frictional energy losses and eliminate the downtime and hazardous emissions from seal failure and leakage. In this study, UNCD films were prepared by microwave plasma chemical vapor deposition utilizing an argon/methane gas mixture. Prior to coating, the SiC seals were subjected to mechanical polishing using different grades of micron-sized diamond powder to produce different starting surfaces with well-controlled surface roughnesses. Following this roughening process, the seals were seeded by mechanical abrasion with diamond nanopowder, and subsequently coated with UNCD. The coated seals were subjected to dynamic wear testing performed at 3600 RPM and 100 psi for up to 10 days during which the seals were periodically removed and inspected. The UNCD-coated seals were examined using Raman microanalysis, scanning electron microscopy, optical profilometry, and adhesion testing before and after the wear testing. These analyses revealed that delamination of the UNCD films was prevented when the initial SiC seal surface had an initial roughness >0.1 {micro}m. In addition, the UNCD surfaces showed no measurable wear as compared to approximately 0.2 {micro}m of wear for the untreated SiC surfaces.

  7. Method for producing fluorinated diamond-like carbon films

    DOEpatents

    Hakovirta, Marko J.; Nastasi, Michael A.; Lee, Deok-Hyung; He, Xiao-Ming

    2003-06-03

    Fluorinated, diamond-like carbon (F-DLC) films are produced by a pulsed, glow-discharge plasma immersion ion processing procedure. The pulsed, glow-discharge plasma was generated at a pressure of 1 Pa from an acetylene (C.sub.2 H.sub.2) and hexafluoroethane (C.sub.2 F.sub.6) gas mixture, and the fluorinated, diamond-like carbon films were deposited on silicon <100>substrates. The film hardness and wear resistance were found to be strongly dependent on the fluorine content incorporated into the coatings. The hardness of the F-DLC films was found to decrease considerably when the fluorine content in the coatings reached about 20%. The contact angle of water on the F-DLC coatings was found to increase with increasing film fluorine content and to saturate at a level characteristic of polytetrafluoroethylene.

  8. Synthesis and characterization of fine grain diamond films

    NASA Technical Reports Server (NTRS)

    Wu, Richard L. C.; Rai, A. K.; Garscadden, Alan; Kee, Patrick; Desai, Hemant D.; Miyoshi, Kazuhisa

    1992-01-01

    A fine grain diamond film has been developed by microwave plasma assisted chemical vapor deposition. Various analytical techniques, including Rutherford backscattering, proton recoil analysis, Raman spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. The grain size of the film was determined from bright and dark field electron micrographs, and found to be 200-1000 A. The films exhibited good optical transmission between 2.5 and 10 microns, with a calculated absorption coefficient of 490/cm. The friction coefficients of this film were found to be 0.035 and 0.030 at dry nitrogen and humid air environments, respectively, and the films had low wear rates.

  9. Optimization of chemical vapor deposition diamond films growth on steel: correlation between mechanical properties, structure, and composition.

    PubMed

    Laikhtman, A; Rapoport, L; Perfilyev, V; Moshkovich, A; Akhvlediani, R; Hoffman, A

    2011-09-01

    In the present work we perform optimization of mechanical and crystalline properties of CVD microcrystalline diamond films grown on steel substrates. A chromium-nitride (Cr-N) interlayer had been previously proposed to serve as a buffer for carbon and iron inter-diffusion and as a matching layer for the widely differing expansion coefficients of diamond and steel. However, adhesion and wear as well as crystalline perfection of diamond films are strongly affected by conditions of both Cr-N interlayer preparation and CVD diamond deposition. In this work we assess the effects of two parameters. The first one is the temperature of the Cr-N interlayer preparation: temperatures in the range of 500 degrees C-800 degrees C were used. The second one is diamond film thickness in the 0.5 microm-2 microm range monitored through variation of the deposition time from approximately 30 min to 2 hours. The mechanical properties of so deposited diamond films were investigated. For this purpose, scratch tests were performed at different indentation loads. The friction coefficient and wear loss were assessed. The mechanical and tribological properties were related to structure, composition, and crystalline perfection of diamond films which were extensively analyzed using different microscopic and spectroscopic techniques. It was found that relatively thick diamond film deposited on the Cr-N interlayer prepared at the temperature similar to that of the CVD process has the best mechanical and adhesion strength. This film was stable without visible cracks around the wear track during all scratch tests with different indentation loads. In other cases, cracking and delamination of the films took place at low to moderate indentation loads.

  10. Chemical vapor deposition of diamond thin films on titanium silicon carbide

    NASA Astrophysics Data System (ADS)

    Yang, Songlan

    2008-10-01

    Chemical vapor deposition (CVD) has been the main method for synthesizing diamond thin films on hetero substrate materials since 1980s. It has been well acknowledged that both nucleation and growth of diamond on non-diamond surfaces without pre-treatment are very difficult and slow. Furthermore, the weak adhesion between the diamond thin films and substrates has been a major problem for widespread application of diamond thin films. Up to now, Si has been the most frequently used substrate for the study of diamond thin films and various methods, including bias and diamond powder scratching, have been applied to enhance diamond nucleation density. In the present study, nucleation and growth of diamond thin films on Ti3SiC2, a newly developed ceramic-metallic material, using Microwave Plasma Enhanced (MPE) and Hot- Filament (HF) CVD reactors were carried out. In addition, synchrotron-based Near Edge Extended X-Ray Absorption Fine Structure Spectroscopy (NEXAFS) was used to identify the electronic and chemical structures of various NCD films. The results from MPECVD showed that a much higher diamond nucleation density and a much higher film growth rate can be obtained on Ti3SiC2 compared with on Si. Consequently, nanocrystalline diamond (NCD) thin films were feasibly synthesized on Ti3SiC2 under the typical conditions for microcrystalline diamond film synthesis. Furthermore, the diamond films on Ti3SiC 2 exhibited better adhesion than on Si. The early stage growth of diamond thin films on Ti3SiC2 by HFCVD indicated that a nanowhisker-like diamond-graphite composite layer, different from diamond nucleation on Si, initially formed on the surface of Ti3SiC2, which resulted in high diamond nucleation density. These results indicate that Ti3SiC 2 has great potentials to be used both as substrates and interlayers on metals for diamond thin film deposition and application. This research may greatly expand the tribological application of both Ti3SiC 2 and diamond thin films

  11. Lower pressure synthesis of diamond material

    DOEpatents

    Lueking, Angela; Gutierrez, Humberto; Narayanan, Deepa; Burgess Clifford, Caroline E.; Jain, Puja

    2010-07-13

    Methods of synthesizing a diamond material, particularly nanocrystalline diamond, diamond-like carbon and bucky diamond are provided. In particular embodiments, a composition including a carbon source, such as coal, is subjected to addition of energy, such as high energy reactive milling, producing a milling product enriched in hydrogenated tetrahedral amorphous diamond-like carbon compared to the coal. A milling product is treated with heat, acid and/or base to produce nanocrystalline diamond and/or crystalline diamond-like carbon. Energy is added to produced crystalline diamond-like carbon in particular embodiments to produce bucky diamonds.

  12. Identification of the diamond-like B-C phase by confocal Raman spectroscopy.

    PubMed

    Zinin, P V; Kudryashov, I; Konishi, N; Ming, L C; Solozhenko, V L; Sharma, S K

    2005-08-01

    The new diamond-like B-C phase was obtained from the graphite-like BC phase in a laser-heated diamond anvil cell at high temperature 2230+/-140 K and high pressure 45 GPa. Raman spectra of the new phase measured at ambient conditions revealed a peak at 1315 cm(-1), which was attributed to longitudinal-optical (LO) mode. The X-Y Raman mapping was used to investigate spatial distribution of the diamond-like phases and was shown to be a powerful tool in studying the sp(2)-to-sp(3) phase transformations occurring in the diamond cell under high temperature and high pressure.

  13. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  14. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  15. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Rough diamond. 592.310 Section 592... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply...

  16. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  17. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  18. Wear of metal fiber brushes

    NASA Astrophysics Data System (ADS)

    Brown, Lloyd Perryman, Jr.

    The goal of this dissertation was determining the wear mechanism of metal fiber brushes on commutators and slip rings with the goal of achieving the lowest possible wear rate. To this end, metal fiber brushes were operated, while conducting direct current, on gold-plated copper rotors with and without unfilled gaps to simulate slip rings and commutators, respectively. Wear rates on unfilled-groove commutators were found to be only modestly higher than on slip ring style rotors. Three possible causes for enhanced metal fiber brush wear on commutators were considered: (i) accelerated "adhesive" wear controlled by contact spots, (ii) fatigue induced wear and (iii) "fiber chopping". Similarly, SEM analysis of fiber tips and wear particles produced scant, if any, evidence of fiber chopping, which would occur as, again, fiber tips extend elastically into the commutator grooves and small slices of them would be "chopped" off by oncoming edges of commutator bars. Finally considered was "modified chopping", wherein fiber tips would be dragged over groove edges, resulting in tensile fracture and chopping. Only a single fiber fragment showed damage that might be compatible with that mechanism. Moreover, the fact that it was exemplified by a single tenuous case, rules it out as significant. The same conclusion also follows from comparing commutator wear rates with that on slip rings. These show good correlation in terms of effective brush pressure, which on commutators is increased because only bars conduct current and gaps do not support load. (Abstract shortened by UMI.)

  19. Research of Influence Electric Conditions Combined ElectroDiamond Processing by on Specific Consumption of Wheel*

    NASA Astrophysics Data System (ADS)

    Lobanov, D. V.; Arkhipov, P. V.; Yanyushkin, A. S.; Skeeba, V. Yu

    2016-08-01

    The paper presents results of stability research of cutting properties of diamond abrasive tools in metal binder for grinding high-strength composite materials, as well as the need to reduce the specific consumption of wheel, as one of the most important economic indicators of processing. Shows a comparative analysis of the results of preliminary researches of various methods diamond processing, in which determined that the minimum specific consumption of wheel reached by combined electro-diamond grinding, combining electrochemical grinding with simultaneous continuous electrochemical correction surface wheel. Were conducted more research directed at identifying the specific consumption the diamond wheel on metallic binder depending from electric conditions combined electrodiamond processing. Researches have established the advantages of combined electro-diamond of hard alloys processing and define rational modes to ensure a satisfactory consumption of the diamond wheel, as well as significantly increasing quality and performance.

  20. Risk Assessment for Tooth Wear.

    PubMed

    Kontaxopoulou, Isavella; Alam, Sonia

    2015-08-01

    Tooth wear has an increasing prevalence in the UK population. The aetiology is commonly multifactorial, and the aetiopathology is through a combination of erosion, attrition, abrasion and abfraction. Erosion is associated with intrinsic or extrinsic acids, and therefore subjects with reflux disease and eating disorders are at increased risk. Fruit juice, fruits and carbonated drink consumption, frequency of consumption and specific habits are also risk factors. Attrition is more prevalent in bruxists. Other habits need to be considered when defining the risk of tooth wear. Abrasion is usually associated with toothbrushing and toothpastes, especially in an already acidic environment. Patients with extensive lesions that affect dentin may be at higher risk, as well as those presenting with unstained lesions. Monitoring of the progress of tooth wear is recommended to identify those with active tooth wear. Indices for tooth wear are a helpful aid. PMID:26556515

  1. Risk Assessment for Tooth Wear.

    PubMed

    Kontaxopoulou, Isavella; Alam, Sonia

    2015-08-01

    Tooth wear has an increasing prevalence in the UK population. The aetiology is commonly multifactorial, and the aetiopathology is through a combination of erosion, attrition, abrasion and abfraction. Erosion is associated with intrinsic or extrinsic acids, and therefore subjects with reflux disease and eating disorders are at increased risk. Fruit juice, fruits and carbonated drink consumption, frequency of consumption and specific habits are also risk factors. Attrition is more prevalent in bruxists. Other habits need to be considered when defining the risk of tooth wear. Abrasion is usually associated with toothbrushing and toothpastes, especially in an already acidic environment. Patients with extensive lesions that affect dentin may be at higher risk, as well as those presenting with unstained lesions. Monitoring of the progress of tooth wear is recommended to identify those with active tooth wear. Indices for tooth wear are a helpful aid.

  2. Progress toward a performance based specification for diamond grinding wheels

    SciTech Connect

    Taylor, J.S.; Piscotty, M.S.; Blaedel, K.L.

    1996-11-12

    This work sought to improve the communication between users and makers of fine diamond grinding wheels. A promising avenue for this is to formulate a voluntary product standard that comprises performance indicators that bridge the gap between specific user requirements and the details of wheel formulations. We propose a set of performance specifiers of figures-of-merit, that might be assessed by straightforward and traceable testing methods, but do not compromise proprietary information of the wheel user of wheel maker. One such performance indicator might be wheel hardness. In addition we consider technologies that might be required to realize the benefits of optimized grinding wheels. A non-contact wheel-to- workpiece proximity sensor may provide a means of monitoring wheel wear and thus wheel position, for wheels that exhibit high wear rates in exchange for improved surface finish.

  3. Raman investigation of diamond films

    SciTech Connect

    Feng, Li-Ming

    1993-12-31

    Extensive Raman investigations were conducted on a wide range of diamond films whose structures were dilineated by optical and confocal microscopy. The Raman Spectra from one extreme of this range indicates a very intense 1331 cm{sup {minus}1} line diagnostic of bulk crystalline diamond. Microscopy of the corresponding film shows the presence of many large true diamond crystallite. The 1331 cm{sup {minus}1} Raman line at the other extreme of the range, however, is virtually absent. It is replaced, at this extreme, by a very broad Raman contour whose maxima occur near 1355 cm{sup {minus}1} and 1575 cm{sup {minus}1}. Optical microscopy now reveals a complete lack of diamond crystallites. The ratio of the integrated Raman intensity of the 1331 cm{sup {minus}1} diamond line to the integral of the entire broad contour extending from {approx}1200 cm{sup {minus}1} to 1800 cm{sup {minus}1}, with maxima near 1355 cm{sup {minus}1} and 1575 cm{sup {minus}1}, was determined. This ratio rises with increasing diamond crystallite size, and it decreases as true diamond crystallites are replaced by diamond-like, but amorphous, hard carbon, which produces the broad Raman contour. The measured intensity ratio was analyzed in terms of a differential equation related to phonon coupling. The increase of the intensity ratio of the 1331 cm{sup {minus}1} diagnostic diamond peak is due to phono-phonon coupling between the diamond crystallites, as the concentration of the amorphous diamond-like carbon decreases. Confocal microscopy indicates many amorphous-like regions interspersed between diamond crystallites which account for the intensity loss, and agree with the Raman intensity measurements. These Raman measurements crystallinity versus amorphous hard-carbon character of thin diamond film.

  4. Most diamonds were created equal

    NASA Astrophysics Data System (ADS)

    Jablon, Brooke Matat; Navon, Oded

    2016-06-01

    Diamonds crystallize deep in the mantle (>150 km), leaving their carbon sources and the mechanism of their crystallization debatable. They can form from elemental carbon, by oxidation of reduced species (e.g. methane) or reduction of oxidized ones (e.g. carbonate-bearing minerals or melts), in response to decreasing carbon solubility in melts or fluids or due to changes in pH. The mechanism of formation is clear for fibrous diamonds that grew from the carbonate-bearing fluids trapped in their microinclusions. However, these diamonds look different and, based on their lower level of nitrogen aggregation, are much younger than most monocrystalline (MC) diamonds. In the first systematic search for microinclusions in MC diamonds we examined twinned crystals (macles), assuming that during their growth, microinclusions were trapped along the twinning plane. Visible mineral inclusions (>10 μm) and nitrogen aggregation levels in these clear macles are similar to other MC diamonds. We found 32 microinclusions along the twinning planes in eight out of 30 diamonds. Eight inclusions are orthopyroxene; four contain >50% K2O (probably as K2(Mg, Ca)(CO3)2); but the major element compositions of the remaining 20 are similar to those of carbonate-bearing high-density fluids (HDFs) found in fibrous diamonds. We conclude that the source of carbon for these macles and for most diamonds is carbonate-bearing HDFs similar to those found here and in fibrous diamonds. Combined with the old ages of MC diamonds (up to 3.5 Ga), our new findings suggest that carbonates have been introduced into the reduced lithospheric mantle since the Archaean and that the mechanism of diamond formation is the same for most diamonds.

  5. Switch wear leveling

    SciTech Connect

    Wu, Hunter; Sealy, Kylee; Gilchrist, Aaron

    2015-09-01

    An apparatus for switch wear leveling includes a switching module that controls switching for two or more pairs of switches in a switching power converter. The switching module controls switches based on a duty cycle control technique and closes and opens each switch in a switching sequence. The pairs of switches connect to a positive and negative terminal of a DC voltage source. For a first switching sequence a first switch of a pair of switches has a higher switching power loss than a second switch of the pair of switches. The apparatus includes a switch rotation module that changes the switching sequence of the two or more pairs of switches from the first switching sequence to a second switching sequence. The second switch of a pair of switches has a higher switching power loss than the first switch of the pair of switches during the second switching sequence.

  6. Structure and properties of diamond and diamond-like films

    SciTech Connect

    Clausing, R.E.

    1993-01-01

    This section is broken into four parts: (1) introduction, (2) natural IIa diamond, (3) importance of structure and composition, and (4) control of structure and properties. Conclusions of this discussion are that properties of chemical vapor deposited diamond films can compare favorably with natural diamond, that properties are anisotropic and are a strong function of structure and crystal perfection, that crystal perfection and morphology are functions of growth conditions and can be controlled, and that the manipulation of texture and thereby surface morphology and internal crystal perfection is an important step in optimizing chemically deposited diamond films for applications.

  7. Genetics Home Reference: Diamond-Blackfan anemia

    MedlinePlus

    ... Home Health Conditions Diamond-Blackfan anemia Diamond-Blackfan anemia Enable Javascript to view the expand/collapse boxes. ... PDF Open All Close All Description Diamond-Blackfan anemia is a disorder of the bone marrow . The ...

  8. Integrated diamond sapphire laser

    NASA Astrophysics Data System (ADS)

    Fork, Richard L.; Walker, Wesley W.; Laycock, Rustin L.; Green, Jason J. A.; Cole, Spencer T.

    2003-10-01

    We use analytic expressions and simulations to examine a model laser gain element formed by integrating diamond and a solid state laser material, such as, Ti:sapphire. The gain element is designed to provide in a single composite structure the thermal management capabilities of diamond and the optical amplification of the laser material. The model results indicate low temperature and a specific radial dependence of the heat transfer coefficient at the material interfaces are needed to access the highest average powers and highest quality optical fields. We outline paths designed to increase average output power of a lowest order mode laser oscillator based on these gain elements to megawatt levels. The long term goal is economically viable solar power delivered safely from space. The short term goal is a design strategy that will facilitate "proof of principle" demonstrations using currently accessible optical pump and thermal management capabilities.

  9. Wear of hot rolling mill rolls: An overview

    NASA Astrophysics Data System (ADS)

    Spuzic, S.; Strafford, K. N.; Subramanian, C.; Savage, G.

    1994-08-01

    Rolling is today one of the most important industrial processes because a greater volume of material is worked by rolling than by any other technique. Roll wear is a multiplex process where mechanical and thermal fatigue combines with impact, abrasion, adhesion and corrosion, which all depend on system interactions rather than material characteristics only. The situation is more complicated in section rolling because of the intricacy of roll geometry. Wear variables and modes are reviewed along with published methods and models used in the study and testing of roll wear. This paper reviews key aspects of roll wear control - roll material properties, roll pass design, and system factors such as temperature, loads and sliding velocity. An overview of roll materials is given including adamites, high Cr materials, high speed tool steels and compound rolls. Non-uniform wear, recognized as the most detrimental phenomenon in section rolling, can be controlled by roll pass design. This can be achieved by computer-aided graphical and statistical analyses of various pass series. Preliminary results obtained from pilot tests conducted using a two-disc hot wear rig and a scratch tester are discussed.

  10. Hexagonal diamonds in meteorites: implications.

    PubMed

    Hanneman, R E; Strong, H M; Bundy, F P

    1967-02-24

    A new polymorph of carbon, hexagonal diamond, has been discovered in the Canyon Diablo and Goalpara meteorites. This phase had been synthesized recently under specific high-pressure conditions in the laboratory. Our results: provide strong evidence that diamonds found in these meteorites were produced by intense shock pressures acting on crystalline graphite inclusions present within the meteorite before impact, rather than by disintegration of larger, statically grown diamonds, as some theories propose. PMID:17830485

  11. Diamond films for laser hardening

    NASA Technical Reports Server (NTRS)

    Albin, S.; Watkins, L.; Ravi, K.; Yokota, S.

    1989-01-01

    Laser-damage experiments were performed on free-standing polycrystalline diamond films prepared by plasma-enhanced CVD. The high laser-induced stress resistance found for this material makes it useful for thin-film coatings for laser optics. Results for diamond-coated silicon substrates demonstrate the enhanced damage threshold imparted by diamond thin-film coatings to materials susceptible to laser damage.

  12. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M.

    1994-01-01

    A method of forming synthetic diamond on a substrate. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond film thickness on the substrate.

  13. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M.

    1993-01-01

    A method of forming synthetic diamond on a substrate is disclosed. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond thickness on the substrate.

  14. Diamond turning of glass

    SciTech Connect

    Blackley, W.S.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. The results will provide systematic data with which to assess machining performance on glasses and amorphous materials

  15. DIAMOND SECONDARY EMITTER

    SciTech Connect

    BEN-ZVI, I.; RAO, T.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

    2005-10-09

    We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron Yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.

  16. DIAMOND PEAK WILDERNESS, OREGON.

    USGS Publications Warehouse

    Sherrod, David R.; Moyle, Phillip R.

    1984-01-01

    No metallic mineral resources were identified during a mineral survey of the Diamond Peak Wilderness in Oregon. Cinder cones within the wilderness contain substantial cinder resources, but similar deposits that are more accessible occur outside the wilderness. The area could have geothermal resources, but available data are insufficient to evaluate their potential. Several deep holes could be drilled in areas of the High Cascades outside the wilderness, from which extrapolations of the geothermal potential of the several Cascade wilderness could be made.

  17. DIAMOND AMPLIFIER FOR PHOTOCATHODES.

    SciTech Connect

    RAO,T.; BEN-ZVI,I.; BURRILL,A.; CHANG,X.; HULBERT,S.; JOHNSON,P.D.; KEWISCH,J.

    2004-06-21

    We report a new approach to the generation of high-current, high-brightness electron beams. Primary electrons are produced by a photocathode (or other means) and are accelerated to a few thousand electron-volts, then strike a specially prepared diamond window. The large Secondary Electron Yield (SEY) provides a multiplication of the number of electrons by about two orders of magnitude. The secondary electrons drift through the diamond under an electric field and emerge into the accelerating proper of the ''gun'' through a Negative Electron Affinity surface of the diamond. The advantages of the new approach include the following: (1) Reduction of the number of primary electrons by the large SEY, i.e. a very low laser power in a photocathode producing the primaries. (2) Low thermal emittance due to the NEA surface and the rapid thermalization of the electrons. (3) Protection of the cathode from possible contamination from the gun, allowing the use of large quantum efficiency but sensitive cathodes. (4) Protection of the gun from possible contamination by the cathode, allowing the use of superconducting gun cavities. (5) Production of high average currents, up to ampere class. (6) Encapsulated design, making the ''load-lock'' systems unnecessary. This paper presents the criteria that need to be taken into account in designing the amplifier.

  18. Raman barometry of diamond formation

    NASA Astrophysics Data System (ADS)

    Izraeli, E. S.; Harris, J. W.; Navon, O.

    1999-11-01

    Pressures and temperatures of the diamond source region are commonly estimated using chemical equilibria between coexisting mineral inclusions. Here we present another type of geobarometer, based on determination of the internal pressure in olivine inclusions and the stresses in the surrounding diamond. Using Raman spectroscopy, pressures of 0.13 to 0.65 GPa were measured inside olivine inclusions in three diamonds from the Udachnaya mine in Siberia. Stresses in the diamond surrounding the inclusions indicated similar pressures (0.11-0.41 GPa). Nitrogen concentration and aggregation state in two of the diamonds yielded mantle residence temperatures of ˜1200°C. Using this temperature and the bulk moduli and thermal expansion of olivine and diamond, we calculated source pressures of 4.4-5.2 GPa. We also derived a linear approximation for the general dependence of the source pressure ( P0, GPa) on source temperature ( T0, °C) and the measured internal pressure in the inclusion ( Pi): P0=(3.259×10 -4Pi+3.285×10 -3) T0+0.9246 Pi+0.319. Raman barometry may be applied to other inclusions in diamonds or other inclusion-host systems. If combined with IR determination of the mantle residence temperature of the diamond, it allows estimation of the pressure at the source based on a non-destructive examination of a single diamond containing a single inclusion.

  19. Conversion of fullerenes to diamonds

    DOEpatents

    Gruen, Dieter M.

    1995-01-01

    A method of forming synthetic diamond or diamond-like films on a substrate surface. The method involves the steps of providing a vapor selected from the group of fullerene molecules or an inert gas/fullerene molecule mixture, providing energy to the fullerene molecules consisting of carbon-carbon bonds, the energized fullerene molecules breaking down to form fragments of fullerene molecules including C.sub.2 molecules and depositing the energized fullerene molecules with C.sub.2 fragments onto the substrate with farther fragmentation occurring and forming a thickness of diamond or diamond-like films on the substrate surface.

  20. Diamonds in ophiolites: Contamination or a new diamond growth environment?

    NASA Astrophysics Data System (ADS)

    Howell, D.; Griffin, W. L.; Yang, J.; Gain, S.; Stern, R. A.; Huang, J.-X.; Jacob, D. E.; Xu, X.; Stokes, A. J.; O'Reilly, S. Y.; Pearson, N. J.

    2015-11-01

    For more than 20 years, the reported occurrence of diamonds in the chromites and peridotites of the Luobusa massif in Tibet (a complex described as an ophiolite) has been widely ignored by the diamond research community. This skepticism has persisted because the diamonds are similar in many respects to high-pressure high-temperature (HPHT) synthetic/industrial diamonds (grown from metal solvents), and the finding previously has not been independently replicated. We present a detailed examination of the Luobusa diamonds (recovered from both peridotites and chromitites), including morphology, size, color, impurity characteristics (by infrared spectroscopy), internal growth structures, trace-element patterns, and C and N isotopes. A detailed comparison with synthetic industrial diamonds shows many similarities. Cubo-octahedral morphology, yellow color due to unaggregated nitrogen (C centres only, Type Ib), metal-alloy inclusions and highly negative δ13C values are present in both sets of diamonds. The Tibetan diamonds (n = 3) show an exceptionally large range in δ15N (-5.6 to + 28.7 ‰) within individual crystals, and inconsistent fractionation between {111} and {100} growth sectors. This in contrast to large synthetic HPHT diamonds grown by the temperature gradient method, which have with δ15N = 0 ‰ in {111} sectors and + 30 ‰ in {100} sectors, as reported in the literature. This comparison is limited by the small sample set combined with the fact the diamonds probably grew by different processes. However, the Tibetan diamonds do have generally higher concentrations and different ratios of trace elements; most inclusions are a NiMnCo alloy, but there are also some small REE-rich phases never seen in HPHT synthetics. These characteristics indicate that the Tibetan diamonds grew in contact with a C-saturated Ni-Mn-Co-rich melt in a highly reduced environment. The stable isotopes indicate a major subduction-related contribution to the chemical environment. The

  1. Effect of source gas chemistry on tribological performance of diamond-like carbon films.

    SciTech Connect

    Erdemir, A.; Eryilmaz, O. L.; Fenske, G. R.; Nilufer, I. B.

    1999-08-23

    In this study, we investigated the effects of various source gases (i. e., methane, ethane, ethylene, acetylene and methane + hydrogen) on friction and wear performance of diamond-like carbon (DLC) films. Specifically, we described the anomalous nature and fundamental friction and wear mechanisms of DLC films derived from gas discharge plasmas with very low to very high hydrogen content. The films were deposited on steel substrates by a plasma enhanced chemical vapor deposition process at room temperature and the tribological tests were performed in dry nitrogen. The results of tribological tests revealed a close correlation between the friction and wear coefficients of the DLC films and the source gas chemistry. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios had much lower friction coefficients and wear rates than the films derived from source gases with lower hydrogen-to-carbon ratios. The lowest friction coefficient (0.002) was achieved with a film derived from 25% methane--75% hydrogen while the films derived from acetylene had a coefficient of 0.15. Similar correlations were observed on wear rates. Specifically, the films derived from hydrogen rich plasmas had the least wear while the films derived from pure acetylene suffered the highest wear. We used a combination of scanning and transmission electron microscopy and Raman spectroscopy to characterize the structural chemistry of the resultant DLC films.

  2. Short Pulse Laser Production of Diamond Thin Films

    SciTech Connect

    Banks, P.S.; Stuart, B.C.; Dinh, L.; Feit, M.D.; Rubenchik, A.M.; McLean, W.; Perry, M.D.

    1998-03-20

    The use of diamond thin films has the potential for major impact in many industrial and scientific applications. These include heat sinks for electronics, broadband optical sensors, windows, cutting tools, optical coatings, laser diodes, cold cathodes, and field emission displays. Attractive properties of natural diamond consist of physical hardness, high tensile yield strength, chemical inertness, low coefficient of friction, high thermal conductivity, and low electrical conductivity. Unfortunately, these properties are not completely realized in currently produced diamond thin films. Chemical vapor deposition, in its many forms, has been the most successful to this point in producing crystalline diamond films microns to millimeters in thickness which are made up of closely packed diamond crystals microns in physical dimension. However, high purity films are difficult to realize due to the use of hydrogen in the growth process which becomes included in the film matrix. These impurities are manifest in film physical properties which are inferior to those of pure crystalline diamond. In addition, the large density of grain boundaries due to the polycrystalline nature of the films reduce the films' diamond-like character. Finally, substrates must be heated to several hundred degrees Celsius which is not suitable for many materials. Pulsed laser deposition is attractive due to its ability to produce high purity films-limited only by the purity of the target. For diamond film production, high purity carbon can be ablated directly by lasers and deposited as thin films at ambient temperatures. However, lasers currently in use generally deliver long (>10 ns) pulses, and the generally explosive nature of laser ablation, in addition to the desired single-atom or single-ion carbon, liberates significant amounts of carbon clusters (C{sub n} where n=2-30) and macroscopic particles (> 1-10 pm) of carbon. These carbon particles interrupt the ordered deposition of crystalline

  3. Picosecond pulsed laser processing of polycrystalline diamond and cubic boron nitride composite materials

    NASA Astrophysics Data System (ADS)

    Warhanek, Maximilian G.; Pfaff, Josquin; Meier, Linus; Walter, Christian; Wegener, Konrad

    2016-03-01

    Capabilities and advantages of laser ablation processes utilizing ultrashort pulses have been demonstrated in various applications of scientific and industrial nature. Of particular interest are applications that require high geometrical accuracy, excellent surface integrity and thus tolerate only a negligible heat-affected zone in the processed area. In this context, this work presents a detailed study of the ablation characteristics of common ultrahard composite materials utilized in the cutting tool industry, namely polycrystalline diamond (PCD) and polycrystalline cubic boron nitride composite (PCBN). Due to the high hardness of these materials, conventional mechanical processing is time consuming and costly. Herein, laser ablation is an appealing solution, since no process forces and no wear have to be taken into consideration. However, an industrially viable process requires a detailed understanding of the ablation characteristics of each material. Therefore, the influence of various process parameters on material removal and processing quality at 10 ps pulse duration are investigated for several PCD and PCBN grades. The main focus of this study examines the effect of different laser energy input distributions, such as pulse frequency and burst pulses, on the processing conditions in deep cutting kerfs and the resulting processing speed. Based on these results, recommendations for efficient processing of such materials are derived.

  4. Study on tribological behavior and cutting performance of CVD diamond and DLC films on Co-cemented tungsten carbide substrates

    NASA Astrophysics Data System (ADS)

    Zhang, Dongcan; Shen, Bin; Sun, Fanghong

    2010-02-01

    The tribological behaviors of diamond and diamond-like carbon (DLC) films play a major role on their machining and mechanical applications. In this study, diamond and diamond-like carbon (DLC) films are deposited on the cobalt cemented tungsten carbide (WC-Co) substrate respectively adopting the hot filament chemical vapor deposition (HFCVD) technique and the vacuum arc discharge with a graphite cathode, and their friction properties are evaluated on a reciprocating ball-on-plate tribometer with counterfaces of silicon nitride (Si 3N 4) ceramic, cemented tungsten carbide (WC) and ball-bearing steel materials, under the ambient air without lubricating condition. Moreover, to evaluate their cutting performance, comparative turning tests are conducted using the uncoated WC-Co and as-fabricated CVD diamond and DLC coated inserts, with glass fiber reinforced plastics (GFRP) composite materials as the workpiece. The as-deposited HFCVD diamond and DLC films are characterized with energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Raman spectroscopy and 3D surface topography based on white-light interferometry. Furthermore, Rocwell C indentation tests are conducted to evaluate the adhesion of HFCVD diamond and DLC films grown onto WC-Co substrates. SEM and 3D surface topography based on white-light interferometry are also used to investigate the worn region on the surfaces of diamond and DLC films. The friction tests suggest that the obtained friction coefficient curves that of various contacts exhibit similar evolution tendency. For a given counterface, DLC films present lower stable friction coefficients than HFCVD diamond films under the same sliding conditions. The cutting tests results indicate that flank wear of the HFCVD diamond coated insert is lower than that of DLC coated insert before diamond films peeling off.

  5. New wear resistant composite material

    SciTech Connect

    Angers, R.; Champagne, B.; Fiset, M.; Chollet, P.

    1983-01-01

    A composite material consisting of WC-Co particles in a steel matrix was fabricated by sintering mixtures of WC-Co particles and a steel powder and infiltrating the sintered pieces with a copper alloy. Its wear resistance and mechanical properties were studied as a function of the content in WC-Co particles and other characteristics of the composite material microstructure. Infiltration provided a simple means to obtain a strong cohesion between WC-Co particles and the steel matrix. An effective matrix protection against wear is obtained with relatively low additions of particles especially with a silica abrasive which is soft with respect to cemented carbide. The experimental results show that this material has good mechanical properties and wear resistance. Depending upon abrasion resistance, wear losses are reduced up to 10 times by a 30 vol% addition of cemented carbide particles.

  6. Design and investigation of properties of nanocrystalline diamond optical planar waveguides.

    PubMed

    Prajzler, Vaclav; Varga, Marian; Nekvindova, Pavla; Remes, Zdenek; Kromka, Alexander

    2013-04-01

    Diamond thin films have remarkable properties comparable with natural diamond. Because of these properties it is a very promising material for many various applications (sensors, heat sink, optical mirrors, chemical and radiation wear, cold cathodes, tissue engineering, etc.) In this paper we report about design, deposition and measurement of properties of optical planar waveguides fabricated from nanocrystalline diamond thin films. The nanocrystalline diamond planar waveguide was deposited by microwave plasma enhanced chemical vapor deposition and the structure of the deposited film was studied by scanning electron microscopy and Raman spectroscopy. The design of the presented planar waveguides was realized on the bases of modified dispersion equation and was schemed for 632.8 nm, 964 nm, 1 310 nm and 1 550 nm wavelengths. Waveguiding properties were examined by prism coupling technique and it was found that the diamond based planar optical element guided one fundamental mode for all measured wavelengths. Values of the refractive indices of our NCD thin film measured at various wavelengths were almost the same as those of natural diamond.

  7. Design and investigation of properties of nanocrystalline diamond optical planar waveguides.

    PubMed

    Prajzler, Vaclav; Varga, Marian; Nekvindova, Pavla; Remes, Zdenek; Kromka, Alexander

    2013-04-01

    Diamond thin films have remarkable properties comparable with natural diamond. Because of these properties it is a very promising material for many various applications (sensors, heat sink, optical mirrors, chemical and radiation wear, cold cathodes, tissue engineering, etc.) In this paper we report about design, deposition and measurement of properties of optical planar waveguides fabricated from nanocrystalline diamond thin films. The nanocrystalline diamond planar waveguide was deposited by microwave plasma enhanced chemical vapor deposition and the structure of the deposited film was studied by scanning electron microscopy and Raman spectroscopy. The design of the presented planar waveguides was realized on the bases of modified dispersion equation and was schemed for 632.8 nm, 964 nm, 1 310 nm and 1 550 nm wavelengths. Waveguiding properties were examined by prism coupling technique and it was found that the diamond based planar optical element guided one fundamental mode for all measured wavelengths. Values of the refractive indices of our NCD thin film measured at various wavelengths were almost the same as those of natural diamond. PMID:23571931

  8. Observation of higher stiffness in nanopolycrystal diamond than monocrystal diamond

    NASA Astrophysics Data System (ADS)

    Tanigaki, Kenichi; Ogi, Hirotsugu; Sumiya, Hitoshi; Kusakabe, Koichi; Nakamura, Nobutomo; Hirao, Masahiko; Ledbetter, Hassel

    2013-08-01

    Diamond is the stiffest known material. Here we report that nanopolycrystal diamond synthesized by direct-conversion method from graphite is stiffer than natural and synthesized monocrystal diamonds. This observation departs from the usual thinking that nanocrystalline materials are softer than their monocrystals because of a large volume fraction of soft grain-boundary region. The direct conversion causes the nondiffusional phase transformation to cubic diamond, producing many twins inside diamond grains. We give an ab initio-calculation twinned model that confirms the stiffening. We find that shorter interplane bonds along [111] are significantly strengthened near the twinned region, from which the superstiff structure originates. Our discovery provides a novel step forward in the search for superstiff materials.

  9. Observation of higher stiffness in nanopolycrystal diamond than monocrystal diamond.

    PubMed

    Tanigaki, Kenichi; Ogi, Hirotsugu; Sumiya, Hitoshi; Kusakabe, Koichi; Nakamura, Nobutomo; Hirao, Masahiko; Ledbetter, Hassel

    2013-01-01

    Diamond is the stiffest known material. Here we report that nanopolycrystal diamond synthesized by direct-conversion method from graphite is stiffer than natural and synthesized monocrystal diamonds. This observation departs from the usual thinking that nanocrystalline materials are softer than their monocrystals because of a large volume fraction of soft grain-boundary region. The direct conversion causes the nondiffusional phase transformation to cubic diamond, producing many twins inside diamond grains. We give an ab initio-calculation twinned model that confirms the stiffening. We find that shorter interplane bonds along [111] are significantly strengthened near the twinned region, from which the superstiff structure originates. Our discovery provides a novel step forward in the search for superstiff materials.

  10. Polyethylene Wear in Knee Arthroplasty.

    PubMed

    Chakravarty, Rajit; Elmallah, Randa D K; Cherian, Jeffrey Jai; Kurtz, Steven M; Mont, Michael A

    2015-10-01

    Polyethylene (PE) wear and osteolysis are common causes for late revisions of knee arthroplasties. Several implant and surgical factors have been implicated in contributing to the development of wear, such as type of bearing surface used, inaccurate articular geometry, and poor knee kinematics. In addition, patient-related factors, such as younger age and higher activity levels, may also contribute to wear. Our purpose was to evaluate and compare the effect of these variables on wear rates following knee arthroplasty. Recently, technological advancements have been aimed at reducing the incidence of wear by improving the PE manufacturing process, creating implants that minimize contact stresses, and refining our surgical techniques. Furthermore, the development of newer highly cross-linked PEs (HXLPEs) and the introduction of additives, such as vitamin E, to the PEs may improve overall implant survivorship. As a result, with the advent of newer implant and PE designs, wear is no longer the most common cause of early failure, though it remains an important factor in limiting long-term implant survivorship. However, there are a few clinical studies evaluating the long-term outcomes of newer HXLPEs and implant designs, with further evaluations necessary to determine the best implant-PE combination for improved knee arthroplasty survivorship. PMID:26030263

  11. Analysis of the elements of secondary adhesion wear in dry turning of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Batista, M.; Salguero, Jorge; Gómez, A.; Alvarez, M.; Marcos, Mariano

    2012-04-01

    Minimizing downtime in machine tools is one of the factors that determine the performance increase of the production processes involved, from different points of view considered: economic, energy and environmental. One of the possible causes that originate of machine is stops due to the need to change the tool by loss of their initial properties due to the wear process that suffer during machining. One of the wear processes which occurs in a wider range of temperatures in the machining of metal alloys is the adhesion wear. In the case of light alloys, secondary adhesion wear occurs a higher often in the form adhered layer (BUL) and ingrowth edge (BUE). This paper analyzes the influence of technological parameters on the formation of the effects of secondary adhesion wear in dry turning UNS A92024 alloy (Al-Cu).

  12. Nanocoatings for High-Efficiency Industrial Hydraulic and Tooling Systems

    SciTech Connect

    Clifton B. Higdon III

    2011-01-07

    Industrial manufacturing in the U.S. accounts for roughly one third of the 98 quadrillion Btu total energy consumption. Motor system losses amount to 1.3 quadrillion Btu, which represents the largest proportional loss of any end-use category, while pumps alone represent over 574 trillion BTU (TBTU) of energy loss each year. The efficiency of machines with moving components is a function of the amount of energy lost to heat because of friction between contacting surfaces. The friction between these interfaces also contributes to downtime and the loss of productivity through component wear and subsequent repair. The production of new replacement parts requires additional energy. Among efforts to reduce energy losses, wear-resistant, low-friction coatings on rotating and sliding components offer a promising approach that is fully compatible with existing equipment and processes. In addition to lubrication, one of the most desirable solutions is to apply a protective coating or surface treatment to rotating or sliding components to reduce their friction coefficients, thereby leading to reduced wear. Historically, a number of materials such as diamond-like carbon (DLC), titanium nitride (TiN), titanium aluminum nitride (TiAlN), and tungsten carbide (WC) have been examined as tribological coatings. The primary objective of this project was the development of a variety of thin film nanocoatings, derived from the AlMgB14 system, with a focus on reducing wear and friction in both industrial hydraulics and cutting tool applications. Proof-of-concept studies leading up to this project had shown that the constituent phases, AlMgB14 and TiB2, were capable of producing low-friction coatings by pulsed laser deposition. These coatings combine high hardness with a low friction coefficient, and were shown to substantially reduce wear in laboratory tribology tests. Selection of the two applications was based largely on the concept of improved mechanical interface efficiencies for

  13. Thermal diffusivity of diamond films

    NASA Technical Reports Server (NTRS)

    Albin, Sacharia; Winfree, William P.; Crews, B. Scott

    1990-01-01

    A laser pulse technique to measure the thermal diffusivity of diamond films deposited on a silicon substrate is developed. The effective thermal diffusivity of diamond film on silicon was measured by observing the phase and amplitude of the cyclic thermal waves generated by the laser pulses. An analytical model is developed to calculate the effective in-plane (face-parallel) diffusivity of a two layer system. The model is used to reduce the effective thermal diffusivity of the diamond/silicon sample to a value for the thermal diffusivity and conductivity of the diamond film. Phase and amplitude measurements give similar results. The thermal conductivity of the films is found to be better than that of type 1a natural diamond.

  14. High efficiency diamond solar cells

    DOEpatents

    Gruen, Dieter M.

    2008-05-06

    A photovoltaic device and method of making same. A layer of p-doped microcrystalline diamond is deposited on a layer of n-doped ultrananocrystalline diamond such as by providing a substrate in a chamber, providing a first atmosphere containing about 1% by volume CH.sub.4 and about 99% by volume H.sub.2 with dopant quantities of a boron compound, subjecting the atmosphere to microwave energy to deposit a p-doped microcrystalline diamond layer on the substrate, providing a second atmosphere of about 1% by volume CH.sub.4 and about 89% by volume Ar and about 10% by volume N.sub.2, subjecting the second atmosphere to microwave energy to deposit a n-doped ultrananocrystalline diamond layer on the p-doped microcrystalline diamond layer. Electrodes and leads are added to conduct electrical energy when the layers are irradiated.

  15. Physical and tribological properties of diamond films grown in argon-carbon plasmas

    SciTech Connect

    Zuiker, C.; Krauss, A.R.; Gruen, D.M.; Pan, X.; Li, J.C.; Csencsits, R.; Erdemir, A.; Bindal, C.; Fenske, G.

    1995-06-01

    Nanocrystalline diamond films have been deposited using a microwave plasma consisting of argon, 2--10% hydrogen and a carbon precursor such as C{sub 60} or CH{sub 4}. It was found that it is possible to grow the diamond phase with both carbon precursors, although the hydrogen concentration in the plasma was 1--2 orders of magnitude lower than normally required in the absence of the argon. Auger electron spectroscopy, x-ray diffraction measurements and transmission electron microscopy indicate the films are predominantly composed of diamond. Surface roughness, as determined by atomic force microscopy and scanning electron microscopy indicate the nanocrystalline films grown in low hydrogen content plasmas grow exceptionally smooth (30--50 nm) to thicknesses of 10 {mu}m. The smooth nanocrystalline films result in low friction coefficients ({mu}=0.04--0.06) and low average wear rates as determined by pin-on-disk measurements.

  16. Wear and friction behavior of Zr implanted D3 steel

    SciTech Connect

    Akbas, N.; Saklakoglu, I.E.; Monteiro, O.R.; Brown, I.G.

    2001-08-23

    Multicharged, pure, high current and pulsed ion beams of Zr have been extracted from a metal vapor vacuum arc (MEVVA) source and implanted into AISI D3 (C: 2-2,35%, Mn: 0,60%, Si: 0,60%, Cr: 11-13,50%, Ni: 0,30%, W: 1%, V: 1%) tool steel samples at the 3,6.1016, 5.1016 and 1.1017 ions/cm2 doses. The wear resistance and friction coefficient have been estimated using pin-on-disc wear tests. Implantation of Zr decreased the wear loss and friction coefficient. RBS, AES and SEM Microprobe analyses were used as a guide for explanation of implantation's effects.

  17. Electron energy loss spectrometry of interstellar diamonds

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Gibbons, Patrick C.; Lewis, Roy S.

    1990-01-01

    The results are reported of electron energy loss spectra (EELS) measurements on diamond residues from carbonaceous meteorites designed to elucidate the structure and composition of interstellar diamonds. Dynamic effective medium theory is used to model the dielectric properties of the diamonds and in particular to synthesize the observed spectra as mixtures of diamond and various pi-bonded carbons. The results are shown to be quantitatively consistent with the idea that diamonds and their surfaces are the only contributors to the electron energy loss spectra of the diamond residues and that these peculiar spectra are the result of the exceptionally small grain size and large specific surface area of the interstellar diamonds.

  18. A review on nozzle wear in abrasive water jet machining application

    NASA Astrophysics Data System (ADS)

    Syazwani, H.; Mebrahitom, G.; Azmir, A.

    2016-02-01

    This paper discusses a review on nozzle wear in abrasive water jet machining application. Wear of the nozzle becomes a major problem since it may affect the water jet machining performance. Design, materials, and life of the nozzle give significance effect to the nozzle wear. There are various parameters that may influence the wear rate of the nozzle such as nozzle length, nozzle inlet angle, nozzle diameter, orifice diameter, abrasive flow rate and water pressure. The wear rate of the nozzle can be minimized by controlling these parameters. The mechanism of wear in the nozzle is similar to other traditional machining processes which uses a cutting tool. The high pressure of the water and hard abrasive particles may erode the nozzle wall. A new nozzle using a tungsten carbide-based material has been developed to reduce the wear rate and improve the nozzle life. Apart from that, prevention of the nozzle wear has been achieved using porous lubricated nozzle. This paper presents a comprehensive review about the wear of abrasive water jet nozzle.

  19. Improved tool grinding machine

    DOEpatents

    Dial, C.E. Sr.

    The present invention relates to an improved tool grinding mechanism for grinding single point diamond cutting tools to precise roundness and radius specifications. The present invention utilizes a tool holder which is longitudinally displaced with respect to the remainder of the grinding system due to contact of the tool with the grinding surface with this displacement being monitored so that any variation in the grinding of the cutting surface such as caused by crystal orientation or tool thicknesses may be compensated for during the grinding operation to assure the attainment of the desired cutting tool face specifications.

  20. Wear of aluminum and hypoeutectic aluminum-silicon alloys in boundary-lubricated pin-on disk sliding

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Brainard, W. A.

    1979-01-01

    The friction and wear of pure aluminum and a number of hypoeutectic aluminum-silicon alloys (with 3 to 12 wt %Si) were studied with a pin-on-disk apparatus. The contacts were lubricated with mineral oil and sliding was in the boundary-lubrication regime at 2.6 cm/sec. Surfaces were analyzed with photomicrographs, scanning electron microscopy, X-ray dispersive analysis, and diamond pyramid hardness measurements. There were two wear regimes for the alloys - high and low - whereas pure aluminum exhibited a high wear rate throughout the test period. Wear rate decreased and the transition stress from high to low wear increased with increasing hardness. There was no correlation between friction coefficient and hardness. A least squares curve fit indicated a wear-rate dependence greater than the inverse first power of hardness. The lower wear rates of the alloys may be due to the composites of silicon platelets in aluminum resulting in increased hardness and thus impairing the shear of the aluminum.

  1. Cutting with diamond wire: Cutting procedures and suggested uses

    NASA Astrophysics Data System (ADS)

    McLaughlin, H. B.

    Diamond impregnated wire is the most versatile cutting tool yet devised. When a wire is properly charged with diamond particles and is drawn back and forth over a material surface, it does a remarkable cutting job. In a number of cases, wire sawing is the only way to perform these operations successfully: (1) for materials which are so fragile that other means of cutting will cause breakage, damage to crystal structure or otherwise impair the specimens, often rendering them useless, (2) for cutting materials which are so expensive that kerf loss becomes a major factor, a wire of the proper diameter with carefully graded diamonds, results in the minimum loss of material, (3) for cutting materials which may be damaged by the frictional heat generated by the high speed abrasive wheels, band saws and other cutting devices, causing hair cracks and craze.

  2. 3D Simulation Modeling of the Tooth Wear Process

    PubMed Central

    Dai, Ning; Hu, Jian; Liu, Hao

    2015-01-01

    Severe tooth wear is the most common non-caries dental disease, and it can seriously affect oral health. Studying the tooth wear process is time-consuming and difficult, and technological tools are frequently lacking. This paper presents a novel method of digital simulation modeling that represents a new way to study tooth wear. First, a feature extraction algorithm is used to obtain anatomical feature points of the tooth without attrition. Second, after the alignment of non-attrition areas, the initial homogeneous surface is generated by means of the RBF (Radial Basic Function) implicit surface and then deformed to the final homogeneous by the contraction and bounding algorithm. Finally, the method of bilinear interpolation based on Laplacian coordinates between tooth with attrition and without attrition is used to inversely reconstruct the sequence of changes of the 3D tooth morphology during gradual tooth wear process. This method can also be used to generate a process simulation of nonlinear tooth wear by means of fitting an attrition curve to the statistical data of attrition index in a certain region. The effectiveness and efficiency of the attrition simulation algorithm are verified through experimental simulation. PMID:26241942

  3. 3D Simulation Modeling of the Tooth Wear Process.

    PubMed

    Dai, Ning; Hu, Jian; Liu, Hao

    2015-01-01

    Severe tooth wear is the most common non-caries dental disease, and it can seriously affect oral health. Studying the tooth wear process is time-consuming and difficult, and technological tools are frequently lacking. This paper presents a novel method of digital simulation modeling that represents a new way to study tooth wear. First, a feature extraction algorithm is used to obtain anatomical feature points of the tooth without attrition. Second, after the alignment of non-attrition areas, the initial homogeneous surface is generated by means of the RBF (Radial Basic Function) implicit surface and then deformed to the final homogeneous by the contraction and bounding algorithm. Finally, the method of bilinear interpolation based on Laplacian coordinates between tooth with attrition and without attrition is used to inversely reconstruct the sequence of changes of the 3D tooth morphology during gradual tooth wear process. This method can also be used to generate a process simulation of nonlinear tooth wear by means of fitting an attrition curve to the statistical data of attrition index in a certain region. The effectiveness and efficiency of the attrition simulation algorithm are verified through experimental simulation.

  4. Targeted computational probabilistic corroboration of experimental knee wear simulator: the importance of accounting for variability.

    PubMed

    Strickland, M A; Dressler, M R; Render, T; Browne, M; Taylor, M

    2011-04-01

    Experimental testing is widely used to predict wear of total knee replacement (TKR) devices. Computational models cannot replace this essential in vitro testing, but they do have complementary strengths and capabilities, which make in silico models a valuable support tool for experimental wear investigations. For effective exploitation, these two separate domains should be closely corroborated together; this requires extensive data-sharing and cross-checking at every stage of simulation and testing. However, isolated deterministic corroborations provide only a partial perspective; in vitro testing is inherently variable, and relatively small changes in the environmental and kinematic conditions at the articulating interface can account for considerable variation in the reported wear rates. Understanding these variations will be key to managing uncertainty in the tests, resulting in a 'cleaner' investigation environment for further refining current theories of wear. This study demonstrates the value of probabilistic in silico methods by describing a specific, targeted corroboration of the AMTI knee wear simulator, using rigid body dynamics software models. A deterministic model of the simulator under displacement-control was created for investigation. Firstly, a large sample of experimental data (N>100) was collated, and a probabilistic computational study (N>1000 trials) was used to compare the kinetic performance envelopes for in vitro and in silico models, to more fully corroborate the mechanical model. Secondly, corresponding theoretical wear-rate predictions were compared to the experimentally reported wear data, to assess the robustness of current wear theories to uncertainty (as distinct from the mechanical variability). The results reveal a good corroboration for the physical mechanics of the wear test rig; however they demonstrate that the distributions for wear are not currently well-predicted. The probabilistic domain is found to be far more sensitive at

  5. Phase Retrieval System for Assessing Diamond Turning and Optical Surface Defects

    NASA Technical Reports Server (NTRS)

    Dean, Bruce; Maldonado, Alex; Bolcar, Matthew

    2011-01-01

    An optical design is presented for a measurement system used to assess the impact of surface errors originating from diamond turning artifacts. Diamond turning artifacts are common by-products of optical surface shaping using the diamond turning process (a diamond-tipped cutting tool used in a lathe configuration). Assessing and evaluating the errors imparted by diamond turning (including other surface errors attributed to optical manufacturing techniques) can be problematic and generally requires the use of an optical interferometer. Commercial interferometers can be expensive when compared to the simple optical setup developed here, which is used in combination with an image-based sensing technique (phase retrieval). Phase retrieval is a general term used in optics to describe the estimation of optical imperfections or aberrations. This turnkey system uses only image-based data and has minimal hardware requirements. The system is straightforward to set up, easy to align, and can provide nanometer accuracy on the measurement of optical surface defects.

  6. Qualitative link between work of adhesion and thermal conductance of metal/diamond interfaces

    SciTech Connect

    Monachon, Christian Weber, Ludger; Schusteritsch, Georg; Kaxiras, Efthimios

    2014-03-28

    We report Time-Domain ThermoReflectance experiments measuring the Thermal Boundary Conductance (TBC) of interfaces between diamond and metal surfaces, based on samples consisting of [111]-oriented diamond substrates with hydrogen or with sp{sup 2} carbon surface terminations created using plasma treatments. In a concurrent theoretical study, we calculate the work of adhesion between Ni, Cu, and diamond interfaces with (111) surface orientation, with or without hydrogen termination of the diamond surface, using first-principles electronic structure calculations based on density functional theory (DFT). We find a positive correlation between the calculated work of adhesion and the measured conductance of these interfaces, suggesting that DFT could be used as a screening tool to identify metal/dielectric systems with high TBC. We also explain the negative effect of hydrogen on the thermal conductance of metal/diamond interfaces.

  7. CVD Diamond Dielectric Accelerating Structures

    SciTech Connect

    Schoessow, P.; Kanareykin, A.; Gat, R.

    2009-01-22

    The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerating structures: high RF breakdown field, extremely low dielectric losses and the highest available thermoconductive coefficient. Using chemical vapor deposition (CVD) cylindrical diamond structures have been manufactured with dimensions corresponding to fundamental TM{sub 01} mode frequencies in the GHz to THz range. Surface treatments are being developed to reduce the secondary electron emission (SEE) coefficient below unity to reduce the possibility of multipactor. The diamond CVD cylindrical waveguide technology developed here can be applied to a variety of other high frequency, large-signal applications.

  8. Tailoring nanocrystalline diamond film properties

    DOEpatents

    Gruen, Dieter M.; McCauley, Thomas G.; Zhou, Dan; Krauss, Alan R.

    2003-07-15

    A method for controlling the crystallite size and growth rate of plasma-deposited diamond films. A plasma is established at a pressure in excess of about 55 Torr with controlled concentrations of hydrogen up to about 98% by volume, of unsubstituted hydrocarbons up to about 3% by volume and an inert gas of one or more of the noble gases and nitrogen up to about 98% by volume. The volume ratio of inert gas to hydrogen is preferably maintained at greater than about 4, to deposit a diamond film on a suitable substrate. The diamond film is deposited with a predetermined crystallite size and at a predetermined growth rate.

  9. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M.

    1994-01-01

    A method of forming synthetic hydrogen defect free diamond or diamond like films on a substrate. The method involves providing vapor containing fullerene molecules with or without an inert gas, providing a device to impart energy to the fullerene molecules, fragmenting at least in part some of the fullerene molecules in the vapor or energizing the molecules to incipient fragmentation, ionizing the fullerene molecules, impinging ionized fullerene molecules on the substrate to assist in causing fullerene fragmentation to obtain a thickness of diamond on the substrate.

  10. 76 FR 4634 - Diamond Sawblades and Parts Thereof From the People's Republic of China (PRC): Rescission of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-26

    ...: Initiation of Antidumping Duty New Shipper Review, 76 FR 775 (January 6, 2011). On January 10, 2011, Hanson... International Trade Administration Diamond Sawblades and Parts Thereof From the People's Republic of China (PRC... Administration, Department of Commerce. SUMMARY: In response to a request from Hanson Diamond Tools (Danyang)...

  11. 76 FR 20317 - Diamond Sawblades and Parts Thereof From the People's Republic of China: Final Rescission of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-12

    ... People's Republic of China: Initiation of Antidumping Duty New Shipper Review, 75 FR 36632 (June 28, 2010... International Trade Administration Diamond Sawblades and Parts Thereof From the People's Republic of China... Diamond Tools Co., Ltd. (``PTDT'').\\1\\ We gave interested parties an opportunity to comment on...

  12. Clinical measurement of tooth wear: Tooth wear indices

    PubMed Central

    López-Frías, Francisco J.; Castellanos-Cosano, Lizett; Martín-González, Jenifer; Llamas-Carreras, José M.

    2012-01-01

    Attrition, erosion, and abrasion result in alterations to the tooth and manifest as tooth wear. Each classification corresponds to a different process with specific clinical features. Classifications made so far have no accurate prevalence data because the indexes do not necessarily measure a specific etiology, or because the study populations can be diverse in age and characteristics. Tooth wears (attrition, erosion and abrasion) is perceived internationally as a growing problem. However, the interpretation and comparison of clinical and epidemiological studies, it is increasingly difficult because of differences in terminology and the large number of indicators/indices that have been developed for the diagnosis, classification and monitoring of the loss of dental hard tissue. These indices have been designed to identify increasing severity and are usually numerical, none have universal acceptance, complicating the evaluation of the true increase in prevalence reported. This article considers the ideal requirements for an erosion index. A literature review is conducted with the aim of analyzing the evolution of the indices used today and discuss whether they meet the clinical needs and research in dentistry. Key words:Tooth wear, tooth wear indices, attrition, erosion, abrasion, abfraction. PMID:24558525

  13. Research on the effect of wear-ring clearances to the performance of centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhao, W. G.; Li, Y. B.; Wang, X. Y.; Sun, J. P.; Wu, G. X.

    2012-11-01

    In order to study the effect of wear-ring clearance on the performance of centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump was simulated with three variable styles of the wear-rings: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Numerical results agree well with the experimental results. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the performance of centrifugal pump. The existence of wear-ring not only has an effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump. Relative to the experimental studies, numerical simulation methods have some advantages, such as low cost, fast and efficient, and easy to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study. In order to study the effect of wear-ring clearance on the performance of centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump was simulated with three variable styles of the wear-rings: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Numerical results agree well with the experimental results. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the performance of centrifugal pump.

  14. Fabrication of high density, adherent films of five-fold symmetric diamond crystals by hot filament chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Wei, Qiuping; Ashfold, M. N. R.; Yu, Z. M.; Ma, Li; Yin, D. F.

    2011-12-01

    Five-fold symmetric diamond crystals (FSDCs) have been grown on a large variety of substrates by hot filament chemical vapour deposition (CVD) methods. High density, adherent films of FSDCs have been prepared on carbon steel with a thermal sprayed WC-Co interlayer, and their quality, adhesion and tribological behaviour were investigated. The diamond films show excellent adhesion under Rockwell indentation testing and when subjected to high-speed, high-load, long-time reciprocating dry sliding ball-on-flat wear tests against a Si 3N 4 counter-face in ambient air.

  15. Method of dehalogenation using diamonds

    DOEpatents

    Farcasiu, Malvina; Kaufman, Phillip B.; Ladner, Edward P.; Anderson, Richard R.

    2000-01-01

    A method for preparing olefins and halogenated olefins is provided comprising contacting halogenated compounds with diamonds for a sufficient time and at a sufficient temperature to convert the halogenated compounds to olefins and halogenated olefins via elimination reactions.

  16. Diamond family of nanoparticle superlattices.

    PubMed

    Liu, Wenyan; Tagawa, Miho; Xin, Huolin L; Wang, Tong; Emamy, Hamed; Li, Huilin; Yager, Kevin G; Starr, Francis W; Tkachenko, Alexei V; Gang, Oleg

    2016-02-01

    Diamond lattices formed by atomic or colloidal elements exhibit remarkable functional properties. However, building such structures via self-assembly has proven to be challenging because of the low packing fraction, sensitivity to bond orientation, and local heterogeneity. We report a strategy for creating a diamond superlattice of nano-objects via self-assembly and demonstrate its experimental realization by assembling two variant diamond lattices, one with and one without atomic analogs. Our approach relies on the association between anisotropic particles with well-defined tetravalent binding topology and isotropic particles. The constrained packing of triangular binding footprints of truncated tetrahedra on a sphere defines a unique three-dimensional lattice. Hence, the diamond self-assembly problem is solved via its mapping onto two-dimensional triangular packing on the surface of isotropic spherical particles. PMID:26912698

  17. Diamond family of nanoparticle superlattices.

    PubMed

    Liu, Wenyan; Tagawa, Miho; Xin, Huolin L; Wang, Tong; Emamy, Hamed; Li, Huilin; Yager, Kevin G; Starr, Francis W; Tkachenko, Alexei V; Gang, Oleg

    2016-02-01

    Diamond lattices formed by atomic or colloidal elements exhibit remarkable functional properties. However, building such structures via self-assembly has proven to be challenging because of the low packing fraction, sensitivity to bond orientation, and local heterogeneity. We report a strategy for creating a diamond superlattice of nano-objects via self-assembly and demonstrate its experimental realization by assembling two variant diamond lattices, one with and one without atomic analogs. Our approach relies on the association between anisotropic particles with well-defined tetravalent binding topology and isotropic particles. The constrained packing of triangular binding footprints of truncated tetrahedra on a sphere defines a unique three-dimensional lattice. Hence, the diamond self-assembly problem is solved via its mapping onto two-dimensional triangular packing on the surface of isotropic spherical particles.

  18. Method of Dehalogenation using Diamonds

    SciTech Connect

    Farcasiu, Malvina; Kaufman, Phillip B.; Ladner, Edward P.; Anderson, Richard R.

    1999-02-26

    A method for preparing olefins and halogenated olefins is provided comprising contacting halogenated compounds with diamonds for a sufficient time and at a sufficient temperature to convert the halogenated compounds to olefins and halogenated olefins via elimination reactions.

  19. Fabrication of amorphous diamond films

    DOEpatents

    Falabella, S.

    1995-12-12

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  20. Amorphous-diamond electron emitter

    DOEpatents

    Falabella, Steven

    2001-01-01

    An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

  1. Critical length scale controls adhesive wear mechanisms.

    PubMed

    Aghababaei, Ramin; Warner, Derek H; Molinari, Jean-Francois

    2016-01-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients. PMID:27264270

  2. Critical length scale controls adhesive wear mechanisms

    PubMed Central

    Aghababaei, Ramin; Warner, Derek H.; Molinari, Jean-Francois

    2016-01-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients. PMID:27264270

  3. Critical length scale controls adhesive wear mechanisms

    NASA Astrophysics Data System (ADS)

    Aghababaei, Ramin; Warner, Derek H.; Molinari, Jean-Francois

    2016-06-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients.

  4. Computational wear prediction of artificial knee joints based on a new wear law and formulation.

    PubMed

    Abdelgaied, Abdellatif; Liu, Feng; Brockett, Claire; Jennings, Louise; Fisher, John; Jin, Zhongmin

    2011-04-01

    Laboratory joint wear simulator testing has become the standard means for preclinical evaluation of wear resistance of artificial knee joints. Recent simulator designs have been advanced and become successful at reproducing the wear patterns observed in clinical retrievals. However, a single simulator test can be very expensive and take a long time to run. On the other hand computational wear modelling is an alternative attractive solution to these limitations. Computational models have been used extensively for wear prediction and optimisation of artificial knee designs. However, all these models have adopted the classical Archard's wear law, which was developed for metallic materials, and have selected wear factors arbitrarily. It is known that such an approach is not generally true for polymeric bearing materials and is difficult to implement due to the high dependence of the wear factor on the contact pressure. Therefore, these studies are generally not independent and lack general predictability. The objective of the present study was to develop a new computational wear model for the knee implants, based on the contact area and an independent experimentally determined non-dimensional wear coefficient. The effects of cross-shear and creep on wear predictions were also considered. The predicted wear volume was compared with the laboratory simulation measurements. The model was run under two different kinematic inputs and two different insert designs with curved and custom designed flat bearing surfaces. The new wear model was shown to be capable of predicting the difference of the wear volume and wear pattern between the two kinematic inputs and the two tibial insert designs. Conversely, the wear factor based approach did not predict such differences. The good agreement found between the computational and experimental results, on both the wear scar areas and volumetric wear rates, suggests that the computational wear modelling based on the new wear law and the

  5. Needs and challenges in precision wear measurement

    SciTech Connect

    Blau, P.J.

    1996-01-10

    Accurate, precise wear measurements are a key element in solving both current wear problems and in basic wear research. Applications range from assessing durability of micro-scale components to accurate screening of surface treatments and thin solid films. Need to distinguish small differences in wear tate presents formidable problems to those who are developing new materials and surface treatments. Methods for measuring wear in ASTM standard test methods are discussed. Errors in using alterate methods of wear measurement on the same test specimen are also described. Human judgemental factors are a concern in common methods for wear measurement, and an experiment involving measurement of a wear scar by ten different people is described. Precision in wear measurement is limited both by the capabilities of the measuring instruments and by the nonuniformity of the wear process. A method of measuring wear using nano-scale indentations is discussed. Current and future prospects for incorporating advanced, higher-precision wear measurement methods into standards are considered.

  6. Wear particle analysis using the ferrograph

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.

    1983-01-01

    The use of the Ferrograph in analyzing wear particles from a variety of different sources is reported. Examples of wear particles from gas turbine engines, bearing tests, friction and wear tests, hydraulic systems, and human joints are illustrated. In addition, the separation of bacteria and human cells is described.

  7. Biocompatibility of chemical-vapour-deposited diamond.

    PubMed

    Tang, L; Tsai, C; Gerberich, W W; Kruckeberg, L; Kania, D R

    1995-04-01

    The biocompatibility of chemical-vapour-deposited (CVD) diamond surfaces has been assessed. Our results indicate that CVD diamond is as biocompatible as titanium (Ti) and 316 stainless steel (SS). First, the amount of adsorbed and 'denatured' fibrinogen on CVD diamond was very close to that of Ti and SS. Second, both in vitro and in vivo there appears to be less cellular adhesion and activation on the surface of CVD diamond surfaces compared to Ti and SS. This evident biocompatibility, coupled with the corrosion resistance and notable mechanical integrity of CVD diamond, suggests that diamond-coated surfaces may be highly desirable in a number of biomedical applications. PMID:7654876

  8. Wear and interfacial transport of material

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1975-01-01

    Bonding across the interface for two solids in contact and the subsequent transfer of material from one surface to another is a direct result of the interfacial bonds being stronger than the cohesive bonds in either of the two solids. Surface tools such as LEED, Auger emission spectroscopy, field ion microscopy, and the atom probe are used to examine adhesive contacts and to determine the direction, nature, quantity of material transfer and properties of the solids which effect transfer and wear. The electronic nature, cohesive binding energies, surface structure, lattice disregistry and distribution of species in surface layers are all found to effect adhesion and transfer or transport for clean surfaces in solid state contact. The influence of adsorbed and reacted surface films from fractions of a monolayer to multilayer reactive films are considered. It is shown that even fractions of a monolayer of surface active species such as oxygen and sulfur can markedly inhibit adhesion and transport.

  9. Science and technology of ultrananocrystalline diamond (UNCD) thin films for multifunctional devices

    SciTech Connect

    Auciello, O.; Krauss, A. R.; Gruen, D. M.; Jayatissa, A.; Sumant, A.; Tucek, J.; Mancini, D.; Molodvan, N.; Erdemir, A.; Ersoy, D.; Gardos, M. N.; Busman, H. G.; Meyer, E. M.

    2000-08-24

    MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. However, Si has poor mechanical and tribological properties, and practical MEMS devices are currently limited primarily to applications involving only bending and flexural motion, such as cantilever accelerometers and vibration sensors. However, because of the poor flexural strength and fracture toughness of Si, and the tendency of Si to adhere to hydrophyllic surfaces, even these simple devices have limited dynamic range. Future MEMS applications that involve significant rolling or sliding contact will require the use of new materials with significantly improved mechanical and tribological properties, and the ability to perform well in harsh environments. Diamond is a superhard material of high mechanical strength, exceptional chemical inertness, and outstanding thermal stability. The brittle fracture strength is 23 times that of Si, and the projected wear life of diamond MEMS moving mechanical assemblies (MEMS-MMAs) is 10,000 times greater than that of Si MMAs. However, as the hardest known material, diamond is notoriously difficult to fabricate. Conventional CVD thin film deposition methods offer an approach to the fabrication of ultra-small diamond structures, but the films have large grain size, high internal stress, poor intergranular adhesion, and very rough surfaces, and are consequently ill-suited for MEMS-MMA applications. A thin film deposition process has been developed that produces phase-pure nanocrystalline diamond with morphological and mechanical properties that are ideally suited for MEMS applications in general, and MMA use in particular. The authors have developed lithographic techniques for the fabrication of diamond microstructure including cantilevers and multi-level devices, acting as precursors to micro-bearings and gears, making nanocrystalline diamond a promising material for the development of high performance MEMS devices.

  10. Wear patterns of, and wear volume formulae for, cylindrically elongated acetabular cup liners.

    PubMed

    Wu, James Shih-Shyn; Hsu, Shu-Ling; Chen, Jian-Horng

    2010-07-01

    This study analyzed the wear patterns of, and wear volume formulae for, cylindrically elongated acetabular cup liners. The geometric patterns of the wear surface were first classified, then wear volume formulae were derived by integral calculus. SolidWorks((R)) software or published formulae were used to verify the accuracy of the proposed formulae. The analytical results showed that the wear shape of the liner can be categorized into seven wear patterns, including the special case of wear at 90 degrees , and the seven corresponding wear formulae were derived. In addition, wear of the cylindrical elongation might add considerably to the volume loss of the liner, depending on the height and shape of the elongation and the depth and direction of the linear penetration, being maximally 21% in the investigated model. The proposed wear formulae and patterns will be useful for more accurate performance evaluation of existing hip components implanted in patients and for the designing of new hip components.

  11. Diamonds: Exploration, mines and marketing

    NASA Astrophysics Data System (ADS)

    Read, George H.; Janse, A. J. A. (Bram)

    2009-11-01

    The beauty, value and mystique of exceptional quality diamonds such as the 603 carat Lesotho Promise, recovered from the Letseng Mine in 2006, help to drive a multi-billion dollar diamond exploration, mining and marketing industry that operates in some 45 countries across the globe. Five countries, Botswana, Russia, Canada, South Africa and Angola account for 83% by value and 65% by weight of annual diamond production, which is mainly produced by four major companies, De Beers, Alrosa, Rio Tinto and BHP Billiton (BHPB), which together account for 78% by value and 72% by weight of annual diamond production for 2007. During the last twelve years 16 new diamond mines commenced production and 4 re-opened. In addition, 11 projects are in advanced evaluation and may begin operations within the next five years. Exploration for diamondiferous kimberlites was still energetic up to the last quarter of 2008 with most work carried out in Canada, Angola, Democratic Republic of the Congo (DRC) and Botswana. Many kimberlites were discovered but no new economic deposits were outlined as a result of this work, except for the discovery and possible development of the Bunder project by Rio Tinto in India. Exploration methods have benefitted greatly from improved techniques of high resolution geophysical aerial surveying, new research into the geochemistry of indicator minerals and further insights into the formation of diamonds and the relation to tectonic/structural events in the crust and mantle. Recent trends in diamond marketing indicate that prices for rough diamonds and polished goods were still rising up to the last quarter of 2008 and subsequently abruptly sank in line with the worldwide financial crisis. Most analysts predict that prices will rise again in the long term as the gap between supply and demand will widen because no new economic diamond discoveries have been made recently. The disparity between high rough and polished prices and low share prices of publicly

  12. Ion Microscopy on Diamond

    NASA Astrophysics Data System (ADS)

    Manfredotti, Claudio

    Because of its physical properties (strong radiation hardness, wide energy gap with a consequent extremely low dark current, very large electron and hole mobility) diamond is a very good candidate for nuclear particle detection, particularly in harsh environments or in conditions of strong radiation damage. Being commonly polycrystalline, diamond samples obtained by chemical vapour deposition (CVD) are not homogeneous, not only from the morphological point of view, but also from the electronic one. As a consequence, as it was indicated quite early starting from 1995, charge collection properties such as charge collection efficiency (cce) are not uniform, but they are depending on the site hit by incoming particle. Moreover, these properties are influenced by previous irradiations which are used in order to improve them and, finally, they are also dependent on the thickness of the sample, since the electronic non uniformity extends also in depth by affecting the profile of the electrical field from top to bottom electrode of the nuclear detector in the standard "sandwich" arrangement. By the use of focussed ion beams, it is possible to investigate these non uniformities by the aid of techniques like IBIC (Ion Beam Induced Charge) and IBIL (Ion Beam Induced Luminescence) with a space resolution of the order of 1 m. This relatively new kind of microscopy, which is called "ion microscopy", is capable not only to give 2D maps of cce, which can be quite precisely compared with morphological images obtained by Scanning Electron Microscopy (generally the grains display a much better cce than intergrain regions), but also to give the electric field profile from one electrode to the other one in a "lateral" arrangement of the ion beam. IBIL, by supplying 2D maps of luminescence intensity at different wavelength, can give information about the presence of specific radiative recombination centers and their distribution in the material. Finally, a new technique called XBIC (X

  13. Diagnostic Tools for Learning Organizations.

    ERIC Educational Resources Information Center

    Moilanen, Raili

    2001-01-01

    The Learning Organization Diamond Tool was designed for holistic analysis of 10 learning organization elements at the individual and organizational levels. A test in 25 Finnish organizations established validity. Comparison with existing tools showed that differences derive from their different purposes. (Contains 33 references.) (SK)

  14. Combined single-crystalline and polycrystalline CVD diamond substrates for diamond electronics

    SciTech Connect

    Vikharev, A. L. Gorbachev, A. M.; Dukhnovsky, M. P.; Muchnikov, A. B.; Ratnikova, A. K.; Fedorov, Yu. Yu.

    2012-02-15

    The fabrication of diamond substrates in which single-crystalline and polycrystalline CVD diamond form a single wafer, and the epitaxial growth of diamond films on such combined substrates containing polycrystalline and (100) single-crystalline CVD diamond regions are studied.

  15. Are diamond nanoparticles cytotoxic?

    PubMed

    Schrand, Amanda M; Huang, Houjin; Carlson, Cataleya; Schlager, John J; Omacr Sawa, Eiji; Hussain, Saber M; Dai, Liming

    2007-01-11

    Finely divided carbon particles, including charcoal, lampblack, and diamond particles, have been used for ornamental and official tattoos since ancient times. With the recent development in nanoscience and nanotechnology, carbon-based nanomaterials (e.g., fullerenes, nanotubes, nanodiamonds) attract a great deal of interest. Owing to their low chemical reactivity and unique physical properties, nanodiamonds could be useful in a variety of biological applications such as carriers for drugs, genes, or proteins; novel imaging techniques; coatings for implantable materials; and biosensors and biomedical nanorobots. Therefore, it is essential to ascertain the possible hazards of nanodiamonds to humans and other biological systems. We have, for the first time, assessed the cytotoxicity of nanodiamonds ranging in size from 2 to 10 nm. Assays of cell viability such as mitochondrial function (MTT) and luminescent ATP production showed that nanodiamonds were not toxic to a variety of cell types. Furthermore, nanodiamonds did not produce significant reactive oxygen species. Cells can grow on nanodiamond-coated substrates without morphological changes compared to controls. These results suggest that nanodiamonds could be ideal for many biological applications in a diverse range of cell types.

  16. Are diamond nanoparticles cytotoxic?

    PubMed

    Schrand, Amanda M; Huang, Houjin; Carlson, Cataleya; Schlager, John J; Omacr Sawa, Eiji; Hussain, Saber M; Dai, Liming

    2007-01-11

    Finely divided carbon particles, including charcoal, lampblack, and diamond particles, have been used for ornamental and official tattoos since ancient times. With the recent development in nanoscience and nanotechnology, carbon-based nanomaterials (e.g., fullerenes, nanotubes, nanodiamonds) attract a great deal of interest. Owing to their low chemical reactivity and unique physical properties, nanodiamonds could be useful in a variety of biological applications such as carriers for drugs, genes, or proteins; novel imaging techniques; coatings for implantable materials; and biosensors and biomedical nanorobots. Therefore, it is essential to ascertain the possible hazards of nanodiamonds to humans and other biological systems. We have, for the first time, assessed the cytotoxicity of nanodiamonds ranging in size from 2 to 10 nm. Assays of cell viability such as mitochondrial function (MTT) and luminescent ATP production showed that nanodiamonds were not toxic to a variety of cell types. Furthermore, nanodiamonds did not produce significant reactive oxygen species. Cells can grow on nanodiamond-coated substrates without morphological changes compared to controls. These results suggest that nanodiamonds could be ideal for many biological applications in a diverse range of cell types. PMID:17201422

  17. Organophosphonate biofunctionalization of diamond electrodes.

    PubMed

    Caterino, R; Csiki, R; Wiesinger, M; Sachsenhauser, M; Stutzmann, M; Garrido, J A; Cattani-Scholz, A; Speranza, Giorgio; Janssens, S D; Haenen, K

    2014-08-27

    The modification of the diamond surface with organic molecules is a crucial aspect to be considered for any bioapplication of this material. There is great interest in broadening the range of linker molecules that can be covalently bound to the diamond surface. In the case of protein immobilization, the hydropathicity of the surface has a major influence on the protein conformation and, thus, on the functionality of proteins immobilized at surfaces. For electrochemical applications, particular attention has to be devoted to avoid that the charge transfer between the electrode and the redox center embedded in the protein is hindered by a thick insulating linker layer. This paper reports on the grafting of 6-phosphonohexanoic acid on OH-terminated diamond surfaces, serving as linkers to tether electroactive proteins onto diamond surfaces. X-ray photoelectron spectroscopy (XPS) confirms the formation of a stable layer on the surface. The charge transfer between electroactive molecules and the substrate is studied by electrochemical characterization of the redox activity of aminomethylferrocene and cytochrome c covalently bound to the substrate through this linker. Our work demonstrates that OH-terminated diamond functionalized with 6-phosphonohexanoic acid is a suitable platform to interface redox-proteins, which are fundamental building blocks for many bioelectronics applications.

  18. Diamond nucleation under bias conditions

    SciTech Connect

    Stoeckel, R.; Stammler, M.; Janischowsky, K.; Ley, L.; Albrecht, M.; Strunk, H.P.

    1998-01-01

    The so-called bias pretreatment allows the growth of heteroepitaxial diamond films by plasma chemical vapor deposition on silicon (100) surfaces. We present plan-view and cross-sectional transmission electron micrographs of the substrate surface at different phases of the bias pretreatment. These observations are augmented by measurements of the etch rates of Si, SiC, and different carbon modifications under plasma conditions and the size distribution of oriented diamond crystals grown after bias pretreatment. Based on these results a new model for diamond nucleation under bias conditions is proposed. First, a closed layer of nearly epitaxially oriented cubic SiC with a thickness of about 10 nm is formed. Subplantation of carbon into this SiC layer causes a supersaturation with carbon and results in the subcutaneous formation of epitaxially oriented nucleation centers in the SiC layer. Etching of the SiC during the bias pretreatment as well as during diamond growth brings these nucleation centers to the sample surface and causes the growth of diamonds epitaxially oriented on the Si/SiC substrate. {copyright} {ital 1998 American Institute of Physics.}

  19. Low wear partially fluorinated polyimides

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.; Hady, W. F.

    1984-01-01

    Tribological studies were conducted on five different polyimide solid bodies formulated from the diamine 2,2-bis 4-(4-aminophenoxy)phenyl hexafluoropropane (4-BDAF) and the dianhydrides pyromellitic acid (PMDS) and benzophenonetetracarboxylic acid (BTDA). The following polyimides were evaluated 4-BDAF/PMDA, 4-BDAF/BTDA, 4-BDAF/80 mole percent PMDA, 20 mole percent BTDA, 4-BDAF/60 mole percent BTDA. Friction coefficients, polyimide wear rates, polyimide surface morphology and transfer films were evaluated at sliding speeds of 0.31 to 11.6 m/s and at temperatures of 25 C to 300 C. The results indicate that the tribological properties are highly dependent on the composition of the polyimide and on the experimental conditions. Two polyimides were found which produced very low wear rates but very high friction coefficients (greater than 0.85) under ambient conditions. They offer considerable potential for high traction types of application such as brakes.

  20. Coatings for wear and lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1978-01-01

    Recent advances in the tribological uses of rf-sputtered and ion plated films of solid film lubricants (laminar solids, soft metals, organic polymers) and wear resistant refractory compounds (carbides, nitrides, silicides) are reviewed. The sputtering and ion plating potentials and the corresponding coatings formed were evaluated relative to the friction coefficient, wear endurance life and mechanical properties. The tribological and mechanical properties for each kind of film are discussed in terms of film adherence, coherence, density, grain size, morphology, internal stresses, thickness, and substrate conditions such as temperature, topography, chemistry and dc-biasing. The ion plated metallic films in addition to improved tribological properties also have better mechanical properties such as tensile strength and fatigue life.

  1. Nuclear fuel assembly wear sleeve

    SciTech Connect

    Cadwell, D.J.; Kmonk, S.

    1983-03-08

    An improved control rod guide tube for use in a fuel assembly in a nuclear reactor. The guide tube extends the complete length of the fuel assembly and has its upper end fastened in a cylindrical housing by swaging the guide tube material into grooves formed in the housing walls. To eliminate wear on the guide tube inner walls caused by hydraulic induced vibratory forces on a control rod adapted to move therein, a thin-walled chrome plated sleeve is threaded into the top end of the guide thimble and extends downwardly a distance sufficient to be engaged by the control rod during reactor operation. The sleeve serves as a highly resistant wear surface between the control rod and walls on the guide tube in the fuel assembly.

  2. Ultimate Atomic Bling: Nanotechnology of Diamonds

    SciTech Connect

    Dahl, Jeremy

    2010-05-25

    Diamonds exist in all sizes, from the Hope Diamond to minuscule crystals only a few atoms across. The smallest of these diamonds are created naturally by the same processes that make petroleum. Recently, researchers discovered that these 'diamondoids' are formed in many different structural shapes, and that these shapes can be used like LEGO blocks for nanotechnology. This talk will discuss the discovery of these nano-size diamonds and highlight current SLAC/Stanford research into their applications in electronics and medicine.

  3. Nanocrystalline diamond synthesized from C60

    SciTech Connect

    Dubrovinskaia, N.; Dubrovinsky, L.; Langehorst, F.; Jacobsen, S.; Liebske, C.

    2010-11-30

    A bulk sample of nanocrystalline cubic diamond with crystallite sizes of 5-12 nm was synthesized from fullerene C{sub 60} at 20(1) GPa and 2000 C using a multi-anvil apparatus. The new material is at least as hard as single crystal diamond. It was found that nanocrystalline diamond at high temperature and ambient pressure kinetically is more stable with respect to graphitization than usual diamonds.

  4. X-ray topographic study of a diamond from Udachnaya: Implications for the genetic nature of inclusions

    NASA Astrophysics Data System (ADS)

    Agrosì, Giovanna; Nestola, Fabrizio; Tempesta, Gioacchino; Bruno, Marco; Scandale, Eugenio; Harris, Jeff

    2016-04-01

    In recent years, several studies have focused on the growth conditions of the diamonds through the analysis of the mineral inclusions trapped in them. In these studies, it is crucial to distinguish between protogenetic, syngenetic and epigenetic inclusions. X-ray topography (XRDT) can be a helpful tool to verify, in a non-destructive way, the genetic nature of inclusions in diamond. With this aim, a diamond from the Udachnaya kimberlite, Siberia, was investigated. The diamond, previously studied by Nestola et al. (2011), has anomalous birefringence and the two largest olivines have typical "diamond-imposed" shapes. The study of the topographic images shows that the diamond exhibits significant deformation fields related to post growth plastic deformation. The absence of dislocations starting from the olivine inclusions, and the dark contrasts around them represent the main results obtained by XRDT, contributing to the elucidation of the relationships between the diamond and the olivines at the micron-meter scale. The dark halo surrounding the inclusions was likely caused by the effect of different thermo-elastic properties between the diamond and the inclusions. The absence of dislocations indicates that the diamond-imposed morphology did not produce the volume distortion commonly associated with the entrapment of the full-grown inclusions and, thus, only based on such evidence, a syngenetic origin could be proposed. In addition, stepped figures optically observed at the interface between diamond and one of the olivines suggest processes of selective partial dissolution that would contribute to a change in the final morphology of inclusions. These results show that a diamond morphology may be imposed to a full-grown (protogenetic) olivine during their encapsulation, suggesting that the bulk of the inclusion is protogenetic, whereas its more external regions, close to the diamond-inclusion interface, could be syngenetic.

  5. Wear of steel by rubber

    NASA Technical Reports Server (NTRS)

    Gent, A. N.; Pulford, C. T. R.

    1978-01-01

    Wear of a steel blade used as a scraper to abrade rubber surfaces has been found to take place much more rapidly on a cis-polyisoprene (natural rubber) surface than on a cis-polybutadiene surface, and much more rapidly in an inert atmosphere than in air. These observations are attributed to the direct attack upon steel of free-radical species generated by mechanical rupture of elastomer molecules during abrasion.

  6. Diamond and diamond-like films for transportation applications

    SciTech Connect

    Perez, J.M.

    1993-01-01

    This section is a compilation of transparency templates which describe the goals of the Office of Transportation Materials (OTM) Tribology Program. The positions of personnel on the OTM are listed. The role and mission of the OTM is reviewed. The purpose of the Tribology Program is stated to be `to obtain industry input on program(s) in tribology/advanced lubricants areas of interest`. The objective addressed here is to identify opportunities for cost effective application of diamond and diamond-like carbon in transportation systems.

  7. Tribological Properties of CrAlN and TiN Coatings Tested in Nano- and Micro-scale Laboratory Wear Tests

    NASA Astrophysics Data System (ADS)

    Hong, Ling; Bian, Guangdong; Hu, Shugen; Wang, Linlin; Dacosta, Herbert

    2015-07-01

    We investigated the tribological properties of CrAlN and TiN coatings produced by electron beam plasma-assisted physical vapor deposition by nano- and micro-scale wear tests. For comparison, we also conducted nano-indentation, nano-scanning wear tests, and pin-on-disk tribotests on uncoated M2 steel. The results indicate that, after nano-scale sliding tests against diamond indenter and pin-on-disk tests against ceramic alumina counterface pins, the CrAlN coating presents superior abrasive wear resistance compared to the TiN-coated and uncoated M2 steel samples. Against aluminum counterface, aluminum is more prone to attach on the CrAlN coating surface compared to TiN coating, but no apparent adhesive wear was observed, which has occurred on the TiN coating.

  8. Characterization of single-crystal diamond grown from the vapor phase on substrates of natural diamond

    SciTech Connect

    Altukhov, A. A.; Vikharev, A. L.; Gorbachev, A. M.; Dukhnovsky, M. P.; Zemlyakov, V. E.; Ziablyuk, K. N.; Mitenkin, A. V.; Muchnikov, A. B. Radishev, D. B.; Ratnikova, A. K.; Fedorov, Yu. Yu.

    2011-03-15

    The results of studies of single-crystal diamond layers with orientation (100) grown on substrates of IIa-type natural diamond by chemical-vapor deposition and of semiconductor diamond obtained subsequently by doping by implantation of boron ions are reported. Optimal conditions of postimplantation annealing of diamond that provide the hole mobility of 1150 cm{sup 2} V{sup -1} s{sup -1} (the highest mobility obtained so far for semiconductor diamond after ion implantation) are given.

  9. Diamond Drilling Specification Manual and Course Outline.

    ERIC Educational Resources Information Center

    British Columbia Dept. of Education, Victoria.

    This publication presents the standards required of a person practicing diamond drilling in western Canada and provides an outline for teaching the skills and knowledge. It is divided into two parts. The Diamond Drilling Specification Manual establishes the levels of skill and knowledge required in the four certified levels of diamond drilling.…

  10. 46 CFR 45.33 - Diamond.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships...

  11. 46 CFR 45.33 - Diamond.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships...

  12. 46 CFR 45.33 - Diamond.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships...

  13. 46 CFR 45.33 - Diamond.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships...

  14. 46 CFR 45.33 - Diamond.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships...

  15. Diamond device architectures for UV laser monitoring

    NASA Astrophysics Data System (ADS)

    Salvatori, S.; Girolami, M.; Oliva, P.; Conte, G.; Bolshakov, A.; Ralchenko, V.; Konov, V.

    2016-08-01

    The paper reviews the status of diamond detectors for UV laser monitoring and imaging. Single pixel detectors, position sensitive architectures, optically activated switches and sensor arrays for beam positioning and imaging are analyzed. The performances of natural diamond and synthetic diamond produced by chemical vapor deposition are compared to evaluate the suitability of such an outstanding material for the described applications.

  16. Ultratough single crystal boron-doped diamond

    SciTech Connect

    Hemley, Russell J; Mao, Ho-Kwang; Yan, Chih-Shiue; Liang, Qi

    2015-05-05

    The invention relates to a single crystal boron doped CVD diamond that has a toughness of at least about 22 MPa m.sup.1/2. The invention further relates to a method of manufacturing single crystal boron doped CVD diamond. The growth rate of the diamond can be from about 20-100 .mu.m/h.

  17. In vitro studies on the effect of particle size on macrophage responses to nanodiamond wear debris

    PubMed Central

    Thomas, Vinoy; Halloran, Brian A.; Ambalavanan, Namasivayam; Catledge, Shane A.; Vohra, Yogesh K.

    2012-01-01

    Nanostructured diamond coatings improve the smoothness and wear characteristics of the metallic component of total hip replacements and increase the longevity of these implants, but the effect of nanodiamond wear debris on macrophages needs to be determined to estimate the long-term inflammatory effects of wear debris. The objective was to investigate the effect of the size of synthetic nanodiamond particles on macrophage proliferation (BrdU incorporation), apoptosis (Annexin-V flow cytometry), metabolic activity (WST-1 assay) and inflammatory cytokine production (qPCR). RAW 264.7 macrophages were exposed to varying sizes (6, 60, 100, 250 and 500 nm) and concentrations (0, 10, 50, 100 and 200 μg ml−1) of synthetic nanodiamonds. We observed that cell proliferation but not metabolic activity was decreased with nanoparticle sizes of 6–100 nm at lower concentrations (50 μg ml−1), and both cell proliferation and metabolic activity were significantly reduced with nanodiamond concentrations of 200 μg ml−1. Flow cytometry indicated a significant reduction in cell viability due to necrosis irrespective of particle size. Nanodiamond exposure significantly reduced gene expression of tumor necrosis factor-α, interleukin-1β, chemokine Ccl2 and platelet-derived growth factor compared to serum-only controls or titanium oxide (anatase 8 nm) nanoparticles, with variable effects on chemokine Cxcl2 and vascular endothelial growth factor. In general, our study demonstrates a size and concentration dependence of macrophage responses in vitro to nanodiamond particles as possible wear debris from diamond-coated orthopedic joint implants. PMID:22342422

  18. Laser-based gluing of diamond-tipped saw blades

    NASA Astrophysics Data System (ADS)

    Hennigs, Christian; Lahdo, Rabi; Springer, André; Kaierle, Stefan; Hustedt, Michael; Brand, Helmut; Wloka, Richard; Zobel, Frank; Dültgen, Peter

    2016-03-01

    To process natural stone such as marble or granite, saw blades equipped with wear-resistant diamond grinding segments are used, typically joined to the blade by brazing. In case of damage or wear, they must be exchanged. Due to the large energy input during thermal loosening and subsequent brazing, the repair causes extended heat-affected zones with serious microstructure changes, resulting in shape distortions and disadvantageous stress distributions. Consequently, axial run-out deviations and cutting losses increase. In this work, a new near-infrared laser-based process chain is presented to overcome the deficits of conventional brazing-based repair of diamond-tipped steel saw blades. Thus, additional tensioning and straightening steps can be avoided. The process chain starts with thermal debonding of the worn grinding segments, using a continuous-wave laser to heat the segments gently and to exceed the adhesive's decomposition temperature. Afterwards, short-pulsed laser radiation removes remaining adhesive from the blade in order to achieve clean joining surfaces. The third step is roughening and activation of the joining surfaces, again using short-pulsed laser radiation. Finally, the grinding segments are glued onto the blade with a defined adhesive layer, using continuous-wave laser radiation. Here, the adhesive is heated to its curing temperature by irradiating the respective grinding segment, ensuring minimal thermal influence on the blade. For demonstration, a prototype unit was constructed to perform the different steps of the process chain on-site at the saw-blade user's facilities. This unit was used to re-equip a saw blade with a complete set of grinding segments. This saw blade was used successfully to cut different materials, amongst others granite.

  19. Deep ultraviolet diamond Raman laser.

    PubMed

    Granados, Eduardo; Spence, David J; Mildren, Richard P

    2011-05-23

    We present a synchronously pumped diamond Raman laser operating at 275.7 nm pumped by the 4th harmonic of a mode locked Nd:YVO4 laser. The laser had a threshold pump pulse energy of 5.8 nJ and generated up to 0.96 nJ pulses at 10.3% conversion efficiency. The results agree well with a numerical model that includes two-photon absorption of the pump and Stokes beams and uses a Raman gain coefficient of diamond of 100 cm/GW. We also report on the observation of nanometer scale two-photon assisted etching of the diamond crystal surfaces. PMID:21643343

  20. Diamond-silicon carbide composite

    DOEpatents

    Qian, Jiang; Zhao, Yusheng

    2006-06-13

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5–8 GPa, T=1400K–2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  1. Interpretation of friction and wear in DLC film: role of surface chemistry and test environment

    NASA Astrophysics Data System (ADS)

    Polaki, S. R.; Kumar, N.; Madapu, K.; Ganesan, K.; Krishna, N. G.; Srivastava, S. K.; Abhaya, S.; Kamruddin, M.; Dash, S.; Tyagi, A. K.

    2016-11-01

    In spite of the large amount of tribological work carried out to explain the friction and wear mechanism in diamond-like carbon (DLC) films, some of the core issues relating to the evolution of reactive species across sliding interfaces and their role on the friction and wear mechanism remain unclear. The phase composition, film density and hydrogen content present in a DLC film can be tailored by substrate biasing during film deposition to achieve a nearly vanishing friction coefficient. Furthermore, nitrogen doping in DLC films significantly improves wear resistance, and sliding occurs in a nearly wearless regime. Undoped and nitrogen-doped DLC films exhibit a nearly frictionless value with ultra-low wear behavior when tests are performed in argon, nitrogen and methane atmospheres. The antifriction and antiwear properties of the DLC films were improved with the reduction of adsorbed oxygen impurities on the film surface. This behavior was understood by correlating the oxygen impurities present at the surface/subsurface region of the DLC film while using x-ray photoelectron spectroscopy and depth-resolved Auger electron spectroscopy.

  2. Comparative study of nanocrystalline diamond deposition on WC-Ni and WC-Co substrates.

    PubMed

    Santos, J A; Neto, V F; Cabral, G; Ruch, D; Grácio, J

    2011-06-01

    Tungsten carbide alloys possess a large number of applications, due to its high hardness, high resistance to heat and to wear, which makes it ideal to be used in wear parts of machinery or on surfaces liable to corrosion, abrasion or high temperatures. For practical applications, it is alloyed with cobalt (Co) or nickel (Ni) in order to improve its properties. The increasing demand of broadening the operation limits of some components, impose the need to improve its life time. Coating these parts with hard and smooth diamond thin film may improve the wear performance and decrease their roughness and friction coefficient. In this work, a comparative study of nanodiamond films deposit onto WC-Co and WC-Ni, by means of a hot-filament Chemical Vapour Deposition (HFCVD) system, is presented. The study was accomplished by varying the CH4/H2/Ar gas ratio of the deposition process. The substrate temperature was kept low (< 700 degrees C) to minimize the thermal stress in the coating-substrate system. The microstructure of the deposited diamond film was characterized using Scanning Electron Microscopy (SEM), Raman spectroscopy and X-ray diffraction spectroscopy. Roughness of the working surfaces were also accessed prior and after the depositions. PMID:21770193

  3. Large piezoresistive effect in surface conductive nanocrystalline diamond

    SciTech Connect

    Janssens, S. D. Haenen, K.; Drijkoningen, S.

    2014-09-08

    Surface conductivity in hydrogen-terminated single crystal diamond is an intriguing phenomenon for fundamental reasons as well as for application driven research. Surface conductivity is also observed in hydrogen-terminated nanocrystalline diamond although the electronic transport mechanisms remain unclear. In this work, the piezoresistive properties of intrinsic surface conductive nanocrystalline diamond are investigated. A gauge factor of 35 is calculated from bulging a diamond membrane of 350 nm thick, with a diameter of 656 μm and a sheet resistance of 1.45 MΩ/sq. The large piezoresistive effect is reasoned to originate directly from strain-induced changes in the resistivity of the grain boundaries. Additionally, we ascribe a small time-dependent fraction of the piezoresistive effect to charge trapping of charge carriers at grain boundaries. In conclusion, time-dependent piezoresistive effect measurements act as a tool for deeper understanding the complex electronic transport mechanisms induced by grain boundaries in a polycrystalline material or nanocomposite.

  4. Superconductivity in CVD Diamond Films

    NASA Astrophysics Data System (ADS)

    Takano, Yoshihiko

    2005-03-01

    The recent news of superconductivity 2.3K in heavily boron-doped diamond synthesized by high pressure sintering was received with considerable surprise (1). Opening up new possibilities for diamond-based electrical devices, a systematic investigation of these phenomena clearly needs to be achieved. Application of diamond to actual devices requires it to be made into the form of wafers or thin films. We show unambiguous evidence for superconductivity in a heavily boron-doped diamond thin film deposited by the microwave plasma assisted chemical vapor deposition (MPCVD) method (2). An advantage of the MPCVD deposited diamond is that it can control boron concentration in its wider range, particularly in (111) oriented films. The temperature dependence of resistivity for (111) and (100) homoepitaxial thin films were measured under several magnetic fields. Superconducting transition temperatures of (111) homoepitaxial film are determined to be 11.4K for Tc onset and 7.2K for zero resistivity. And the upper critical field is estimated to be about 8T. These values are 2-3 times higher than these ever reported (1,3). On other hand, for (100) homoepitaxial film, Tc onset and Tc zero resistivity were estimated to be 6.3 and 3.2K respectively. The superconductivity in (100) film was strongly suppressed even at the same boron concentration. These differences of superconductivity in film orientation will be discussed. These findings established the superconductivity as a universal property of boron-doped diamond, demonstrating that device application is indeed a feasible challenge. 1. E. A. Ekimov et al. Nature, 428, 542 (2004). 2. Y. Takano et al., Appl. Phys. Lett. 85, 2851 (2004). 3. E. Bustarret et al., ond-mat 0408517.

  5. Friction and wear in hot forging of steels

    SciTech Connect

    Daouben, E.; Dubar, L.; Dubar, M.; Deltombe, R.; Dubois, A.; Truong-Dinh, N.; Lazzarotto, L.

    2007-04-07

    In the field of hot forging of steels, the mastering of wear phenomena enables to save cost production, especially concerning tools. Surfaces of tools are protected thanks to graphite. The existing lubrication processes are not very well known: amount and quality of lubricant, lubrication techniques have to be strongly optimized to delay wear phenomena occurrence. This optimization is linked with hot forging processes, the lubricant layers must be tested according to representative friction conditions. This paper presents the first part of a global study focused on wear phenomena encountered in hot forging of steels. The goal is the identification of reliable parameters, in order to bring knowledge and models of wear. A prototype testing stand developed in the authors' laboratory is involved in this experimental analysis. This test is called Warm and Hot Upsetting Sliding Test (WHUST). The stand is composed of a heating induction system and a servo-hydraulic system. Workpieces taken from production can be heated until 1200 deg. C. A nitrided contactor representing the tool is heated at 200 deg. C. The contactor is then coated with graphite and rubs against the workpiece, leaving a residual track on it. Friction coefficient and surface parameters on the contactor and the workpiece are the most representative test results. The surface parameters are mainly the sliding length before defects occurrence, and the amplitude of surface profile of the contactor. The developed methodology will be first presented followed by the different parts of the experimental prototype. The results of experiment show clearly different levels of performance according to different lubricants.

  6. Adhesion and material transfer between aluminum and surfaces coated with diamond-like carbon and other coatings

    NASA Astrophysics Data System (ADS)

    Konca, Erkan

    Adhesion and transfer of aluminum to the surfaces of tool coatings that are potential candidates for dry machining of Al-Si alloys were investigated. First, 319 Al alloy pins were tested against various industrial coatings (CrN, TiB2, TiAlN, TiN, and TiCN) using a pin-on-disc tribometer. The analyzed Scanning Electron Microscope (SEM) images of the wear tracks were used to rank the coatings according to the amount of Al transferred on their surfaces. In general, the TiB2 and TiCN coatings exhibited the least amount of Al transfer on their surfaces compared to the other coatings. Second, the tribological behaviour of the diamond-like carbon (DLC) coatings against Al was investigated since aluminum has much lower tendency to adhere to DLC in ambient air compared to other hard coatings tested. Magnetron sputtered non hydrogenated DLC coatings were tested against 319 Al, tungsten carbide (WC) and sapphire (Al20O3) at 120, 300 and 400°C and under various test atmospheres including air (0-85% RH), vacuum, inert gases (Ar, He and N2) and 40% H2-60% He. Although much softer than WC and Al2O3, 319 Al alloy inflicted the most severe wear of non-hydrogenated DLC especially at elevated temperatures. Non-hydrogenated DLC coatings showed high coefficient of friction, (COF), (0.45-0.75) and high wear rates in inert gases and vacuum compared to ambient air (COF= 0.09-0.16). Very low COF values (0.01-0.02) were observed in 40% H2-60% He mixture. The low COF values in ambient air and in 40% H2-60% He mixture were associated with formation of carbonaceous transfer layers on counterfaces. Formation of easy-to-shear transfer layer together with adsorption and dissociation of the atmospheric water on the sliding surfaces were suggested as the possible mechanisms that minimize COF in ambient air. To elucidate the effect of material properties on adhesion, 1100 Al, Cu, and Ti were tested against CrN, non-hydrogenated DLC, and TiB2 coatings in ambient air and argon. Cu exhibited the least

  7. Wear mechanism and wear prevention in coal-fueled diesel engines. Task 3, Traditional approaches to wear prevention

    SciTech Connect

    Schwalb, J.A.

    1991-06-01

    Contamination of the lube-oil with hard abrasive particles leads to a three-body abrasive wear mechanism that highly accelerates piston ring/cylinder liner wear in coal-fueled diesel engines. One approach to reducing that wear is to modify the size and orientation of surface asperities on the cylinder to enhance the formation of a hydrodynamic film, and to provide avenues of escape for particles that would otherwise be trapped in the wear zone. Another approach is to introduce additives into the contaminated lube-oil that further enhance hydrodynamic film formation, form chemical films on the wearing surfaces, or form films on the contaminant particles. This work focuses on defining the effects of cylinder liner surface finish, various configurations of slots in the cylinder liner surface, and various additives in the contaminated lube-oil on the wear process. Wear tests were initiated in a bench apparatus using coal-ash contaminated lube-oil to test the various wear configurations. The results of these tests indicate that the formation of a hydrodynamic film between the ring and cylinder specimens is enhanced by increasing surface roughness, and by orienting the surface asperities normal to the direction of ring travel but modifications to the cylinder liner surface did not greatly reduce the wear rate. Additives to the lubricant seemed to have a much more significant effect on wear, with a dispersant additive highly accelerating the wear, while a detergent additive was able to reduce the wear almost to the rate achieved where there was no contaminant.

  8. Comparison between PEEK and Ti6Al4V concerning micro-scale abrasion wear on dental applications.

    PubMed

    Sampaio, M; Buciumeanu, M; Henriques, B; Silva, F S; Souza, J C M; Gomes, J R

    2016-07-01

    In the oral cavity, abrasive wear is predictable at exposed tooth or restorative surfaces, during mastication and tooth brushing. Also, wear can occur at contacting surfaces between the Ti-based prosthetic structures and implants in presence of abrasive compounds from food or toothpaste. Thus, the aim of this work was to compare the abrasive wear resistance of PEEK and Ti6Al4V on three-body abrasion related to different hydrated silica content and loads. Surfaces of Ti6Al4V or PEEK cylinders (8mm diameter and 4mm height) were wet ground on SiC papers and then polished with 1µm diamond paste. After that, surfaces were ultrasonically cleaned in propyl alcohol for 15min and then in distilled water for 10min. Micro-scale abrasion tests were performed at 60rpm and on different normal loads (0.4, 0.8 or 1.2N) after 600 ball revolutions using suspensions with different weight contents of hydrated silica. After abrasive tests, wear scars on flat samples were measured to quantify the wear volume and characterized by scanning electron microscope (SEM) to identify the dominant wear mechanisms. Results showed a higher volume loss rate on PEEK than that recorded on Ti6Al4V,, when subjected to three-body abrasion tests involving hydrated silica suspensions. An increase in volume loss was noted on both tested materials when the abrasive content or load was increased. PEEK was characterized by less wear resistance than that on Ti6Al4V after micro-scale abrasion wear in contact with hydrated silica particles, as commonly found in toothpastes. PMID:26849309

  9. Electron Microscopy of Natural and Epitaxial Diamond

    NASA Technical Reports Server (NTRS)

    Posthill, J. B.; George, T.; Malta, D. P.; Humphreys, T. P.; Rudder, R. A.; Hudson, G. C.; Thomas, R. E.; Markunas, R. J.

    1993-01-01

    Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. Ultimately, it is preferable to use low-defect-density single crystal diamond for device fabrication. We have previously investigated polycrystalline diamond films with transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and homoepitaxial films with SEM-based techniques. This contribution describes some of our most recent observations of the microstructure of natural diamond single crystals and homoepitaxial diamond thin films using TEM.

  10. Thermal Conductivity Of Natural Type IIa Diamond

    NASA Technical Reports Server (NTRS)

    Vandersande, Jan; Vining, Cronin; Zoltan, Andrew

    1992-01-01

    Report describes application of flash diffusivity method to measure thermal conductivity of 8.04 x 8.84 x 2.35-mm specimen of natural, white, type-IIa diamond at temperatures between 500 and 1,250 K. Provides baseline for comparison to isotopically pure (12C) diamond. Results used as reference against which diamond films produced by chemical-vapor deposition at low pressures can be compared. High thermal conductivity of diamond exploited for wide variety of applications, and present results also used to estimate heat-conduction performances of diamond films in high-temperature applications.

  11. Diamond Ablators for Inertial Confinement Fusion

    SciTech Connect

    Biener, J; Mirkarimi, P B; Tringe, J W; Baker, S L; Wang, Y M; Kucheyev, S O; Teslich, N E; Wu, K J; Hamza, A V; Wild, C; Woerner, E; Koidl, P; Bruehne, K; Fecht, H

    2005-06-21

    Diamond has a unique combination of physical properties for the inertial confinement fusion ablator application, such as appropriate optical properties, high atomic density, high yield strength, and high thermal conductivity. Here, we present a feasible concept to fabricate diamond ablator shells. The fabrication of diamond capsules is a multi-step process, which involves diamond chemical vapor deposition on silicon mandrels followed by polishing, microfabrication of holes, and removing of the silicon mandrel by an etch process. We also discuss the pros and cons of coarse-grained optical quality and nanocrystalline chemical vapor deposition diamond films for the ablator application.

  12. Radiation monitoring with CVD diamonds in BABAR

    NASA Astrophysics Data System (ADS)

    Edwards, A. J.; Bruinsma, M.; Burchat, P.; Kagan, H.; Kass, R.; Kirkby, D.; Petersen, B. A.; Pulliam, T.

    2005-10-01

    The BABAR experiment has been using two polycrystalline chemical-vapor-deposition (pCVD) diamonds for radiation monitoring for nearly 2 years. In July 2005, an additional 12 diamond based radiation sensors will be installed inside the BABAR detector. These diamonds will take over the function of 12 silicon PIN-diodes that are currently used in the radiation protection and monitoring system. We describe our highly successful experience with using pCVD diamond radiation sensors in a high energy physics experiment. We also detail our findings of persistent signal currents and magnetically suppressed erratic dark currents in pCVD diamond based radiation sensors.

  13. Recent results on CVD diamond radiation sensors

    NASA Astrophysics Data System (ADS)

    Weilhammer, P.; Adam, W.; Bauer, C.; Berdermann, E.; Bogani, F.; Borchi, E.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; v. d. Eijk, R.; van Eijk, B.; Fallou, A.; Fish, D.; Fried, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Knopfle, K. T.; Krammer, M.; Manfredi, P. F.; Meier, D.; LeNormand; Pan, L. S.; Pernegger, H.; Pernicka, M.; Plano, R.; Re, V.; Riester, J. L.; Roe, S.; Roff; Rudge, A.; Schieber, M.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Tapper, R. J.; Tesarek, R.; Thomson, G. B.; Trawick, M.; Trischuk, W.; Turchetta, R.; RD 42 Collaboration

    1998-02-01

    CVD diamond radiation sensors are being developed for possible use in trackers in the LHC experiments. The diamond promises to be radiation hard well beyond particle fluences that can be tolerated by Si sensors. Recent results from the RD 42 collaboration on charge collection distance and on radiation hardness of CVD diamond samples will be reported. Measurements with diamond tracking devices, both strip detectors and pixel detectors, will be discussed. Results from beam tests using a diamond strip detector which was read out with fast, 25 ns shaping time, radiation-hard pipeline electronics will be presented.

  14. Characterization of Wear Mechanisms in Distorted Conical Picks After Coal Cutting

    NASA Astrophysics Data System (ADS)

    Dewangan, Saurabh; Chattopadhyaya, Somnath

    2016-01-01

    The interest in understanding the wear mechanisms of cemented carbide (CC) is not a new development. For a long time, there have been studies on different wear mechanisms under different coal/rock cutting conditions. These studies have helped improving the quality of CC, thereby preventing such wearing of tools. Due to highly unpredictable character of coal/rock, the wearing phenomena cannot be attributed to one single domain of conditions. However, one conclusion that can be drawn in this context is that, under similar working conditions, similar types of CC undergo similar nature of wearing process. An optimum combination of high wear resistance, strength and hardness has facilitated widespread application of CC in the field of mining engineering. The abrasive parts of the mining tools are made of CC materials. The current study is focussed on a detailed characterization of the wear mechanisms of conical picks, which are used for coal mining. Conical picks consist of a steel body with an inserted cone-shaped CC tip. After being used for a certain period of time, both, the CC tip and the steel body get distorted. In this study, selection of appropriate samples was followed by critical observation of them through field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). In the previous study, we explained the distortion process of both, the tip as well as the body, using the SEM images. For the present study, two samples were taken from our previous investigation for further analysis. Three other samples were also included in the present study. Seven different types of wear mechanisms, such as, cracking and crushing, cavity formation, coal intermixing, chemical degradation along with abrasion, long and deep cracks, heating effect and body deformation were observed in the five tool samples.

  15. Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk.

    PubMed

    Wang, Song; Wang, Fei; Liao, Zhenhua; Wang, Qingliang; Liu, Yuhong; Liu, Weiqiang

    2015-10-01

    A ball-on-socket contact configuration was designed to simulate an artificial cervical disk in structure. UHMWPE (ultra high molecular weight polyethylene) hot pressed by powders and Ti6Al4V alloy were selected as the material combination of ball and socket. The socket surface was coated by a ~500 nm C-DLC (carbon ion implantation-diamond like carbon) mixed layer to improve its surface nano hardness and wear resistance. The torsional fretting wear behavior of the ball-on-socket model was tested at different angular displacements under 25% bovine serum lubrication with an axial force of 100 N to obtain more realistic results with that in vivo. The fretting running regimes and wear damage characteristics as well as wear mechanisms for both ball and socket were studied based on 2D (two dimension) optical microscope, SEM (scanning electron microscope) and 3D (three dimension) profiles. With the increase of angular displacement amplitude from 1° to 7°, three types of T-θ (Torsional torque-angular displacement amplitude) curves (i.e., linear, elliptical and parallelogram loops) corresponding to running regimes of PSR (partial slip regime), MR (mixed regime) and SR (slip regime) were observed and analyzed. Both the central region and the edge zone of the ball and socket were damaged. The worn surfaces were characterized by wear scratches and wear debris. In addition, more severe wear damage and more wear debris appeared on the central region of the socket at higher angular displacement amplitude. The dominant damage mechanism was a mix of surface scratch, adhesive wear and abrasive wear for the UHMWPE ball while that for the coated socket was abrasive wear by PE particles and some polishing and rolling process on the raised overgrown DLC grains. The frictional kinetic behavior, wear type, damage region and damage mechanism for the ball-on-socket model revealed significant differences with those of a ball-on-flat contact while showing better consistency with that of in

  16. Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk.

    PubMed

    Wang, Song; Wang, Fei; Liao, Zhenhua; Wang, Qingliang; Liu, Yuhong; Liu, Weiqiang

    2015-10-01

    A ball-on-socket contact configuration was designed to simulate an artificial cervical disk in structure. UHMWPE (ultra high molecular weight polyethylene) hot pressed by powders and Ti6Al4V alloy were selected as the material combination of ball and socket. The socket surface was coated by a ~500 nm C-DLC (carbon ion implantation-diamond like carbon) mixed layer to improve its surface nano hardness and wear resistance. The torsional fretting wear behavior of the ball-on-socket model was tested at different angular displacements under 25% bovine serum lubrication with an axial force of 100 N to obtain more realistic results with that in vivo. The fretting running regimes and wear damage characteristics as well as wear mechanisms for both ball and socket were studied based on 2D (two dimension) optical microscope, SEM (scanning electron microscope) and 3D (three dimension) profiles. With the increase of angular displacement amplitude from 1° to 7°, three types of T-θ (Torsional torque-angular displacement amplitude) curves (i.e., linear, elliptical and parallelogram loops) corresponding to running regimes of PSR (partial slip regime), MR (mixed regime) and SR (slip regime) were observed and analyzed. Both the central region and the edge zone of the ball and socket were damaged. The worn surfaces were characterized by wear scratches and wear debris. In addition, more severe wear damage and more wear debris appeared on the central region of the socket at higher angular displacement amplitude. The dominant damage mechanism was a mix of surface scratch, adhesive wear and abrasive wear for the UHMWPE ball while that for the coated socket was abrasive wear by PE particles and some polishing and rolling process on the raised overgrown DLC grains. The frictional kinetic behavior, wear type, damage region and damage mechanism for the ball-on-socket model revealed significant differences with those of a ball-on-flat contact while showing better consistency with that of in

  17. Stick-slip friction and wear of articular joints

    PubMed Central

    Lee, Dong Woog; Banquy, Xavier; Israelachvili, Jacob N.

    2013-01-01

    Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps—separating regimes of smooth and stick-slip sliding; damage generally occurs within the stick-slip regimes. Prolonged exposure of cartilage surfaces to stick-slip sliding resulted in a significant increase of surface roughness, indicative of severe morphological changes of the cartilage superficial zone. To further investigate the factors that are conducive to stick-slip and wear, we selectively digested essential components of cartilage: type II collagen, hyaluronic acid (HA), and glycosaminoglycans (GAGs). Compared with the normal cartilage, HA and GAG digestions modified the stick-slip behavior and increased surface roughness (wear) during sliding, whereas collagen digestion decreased the surface roughness. Importantly, friction forces increased up to 2, 10, and 5 times after HA, GAGs, and collagen digestion, respectively. Also, each digestion altered the friction map in different ways. Our results show that (i) wear is not directly related to the friction coefficient but (ii) more directly related to stick-slip sliding, even when present at small amplitudes, and that (iii) the different molecular components of joints work synergistically to prevent wear. Our results also suggest potential noninvasive diagnostic tools for sensing stick-slip in joints. PMID:23359687

  18. Stick-slip friction and wear of articular joints.

    PubMed

    Lee, Dong Woog; Banquy, Xavier; Israelachvili, Jacob N

    2013-02-12

    Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps--separating regimes of smooth and stick-slip sliding; damage generally occurs within the stick-slip regimes. Prolonged exposure of cartilage surfaces to stick-slip sliding resulted in a significant increase of surface roughness, indicative of severe morphological changes of the cartilage superficial zone. To further investigate the factors that are conducive to stick-slip and wear, we selectively digested essential components of cartilage: type II collagen, hyaluronic acid (HA), and glycosaminoglycans (GAGs). Compared with the normal cartilage, HA and GAG digestions modified the stick-slip behavior and increased surface roughness (wear) during sliding, whereas collagen digestion decreased the surface roughness. Importantly, friction forces increased up to 2, 10, and 5 times after HA, GAGs, and collagen digestion, respectively. Also, each digestion altered the friction map in different ways. Our results show that (i) wear is not directly related to the friction coefficient but (ii) more directly related to stick-slip sliding, even when present at small amplitudes, and that (iii) the different molecular components of joints work synergistically to prevent wear. Our results also suggest potential noninvasive diagnostic tools for sensing stick-slip in joints.

  19. Adhesive bonding and brazing of nanocrystalline diamond foil onto different substrate materials

    NASA Astrophysics Data System (ADS)

    Lodes, Matthias A.; Sailer, Stefan; Rosiwal, Stefan M.; Singer, Robert F.

    2013-10-01

    Diamond coatings are used in heavily stressed industrial applications to reduce friction and wear. Hot-filament chemical vapour deposition (HFCVD) is the favourable coating method, as it allows a coating of large surface areas with high homogeneity. Due to the high temperatures occurring in this CVD-process, the selection of substrate materials is limited. With the desire to coat light materials, steels and polymers a new approach has been developed. First, by using temperature-stable templates in the HFCVD and stripping off the diamond layer afterwards, a flexible, up to 150 μm thick and free standing nanocrystalline diamond foil (NCDF) can be produced. Afterwards, these NCDF can be applied on technical components through bonding and brazing, allowing any material as substrate. This two-step process offers the possibility to join a diamond layer on any desired surface. With a modified scratch test and Rockwell indentation testing the adhesion strength of NCDF on aluminium and steel is analysed. The results show that sufficient adhesion strength is reached both on steel and aluminium. The thermal stress in the substrates is very low and if failure occurs, cracks grow undercritically. Adhesion strength is even higher for the brazed samples, but here crack growth is critical, delaminating the diamond layer to some extent. In comparison to a sample directly coated with diamond, using a high-temperature CVD interlayer, the brazed as well as the adhesively bonded samples show very good performance, proving their competitiveness. A high support of the bonding layer could be identified as crucial, though in some cases a lower stiffness of the latter might be acceptable considering the possibility to completely avoid thermal stresses which occur during joining at higher temperatures.

  20. Science and technology of ultrananocrystalline diamond (UNCD) thin films for multifunctional devices.

    SciTech Connect

    Auciello, O.; Gruen, D. M.; Krauss, A. R.; Jayatissa, A.; Sumant, A.; Tucek, J.; Mancini, D.; Moldovan, N.; Erdemir, A.; Ersoy, D.; Gardos, M. N.; Busmann, H. G.; Meyer, E. M.

    2000-11-15

    MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. However, Si has poor mechanical and tribological properties, and practical MEMS devices are currently limited primarily to applications involving only bending and flexural motion, such as cantilever accelerometers and vibration sensors, However, because of the poor flexural strength and fracture toughness of Si, and the tendency of Si to adhere to hydrophyllic surfaces, even these simple devices have limited dynamic range. Future MEMS applications that involve significant rolling or sliding contact will require the use of new materials with significantly improved mechanical and tribological properties, and the ability to perform well in harsh environments. Diamond is a superhard material of high mechanical strength, exceptional chemical inertness, and outstanding thermal stability. The brittle fracture strength is 23 times that of Si, and the projected wear life of diamond MEMS moving mechanical assemblies (MEMS-MMAS) is 10,000 times greater than that of Si MMAs. However, as the hardest known material, diamond is notoriously difficult to fabricate. Conventional CVD thin film deposition methods offer an approach to the fabrication of ultra-small diamond structures, but the films have large grain size, high internal stress, poor intergranular adhesion, and very rough surfaces, and are consequently ill-suited for MEMS-MMA applications. A thin film deposition process has been developed that produces phase-pure ultrananocrystalline diamond (UNCD) with morphological and mechanical properties that are ideally suited for MEMS applications in general, and MMA use in particular. We have developed lithographic techniques for the fabrication of diamond microstructure including cantilevers and multi-level devices, acting as precursors to micro-bearings and gears, making UNCD a promising material for the development of high performance MEMS devices.

  1. CVD diamond film oxidation resistance research

    NASA Astrophysics Data System (ADS)

    Jing, Longwei; Wang, Xiaoping; Wang, Lijun; Pan, Xiufang; Sun, Yiqing; Wang, Jinye; Sun, Hongtao

    2013-12-01

    Diamond films were deposited on a silicon substrate by microwave plasma chemical vapor deposition system, and its oxidation experiments were carried out in atmospheric environmental condition by using a muffle furnace. Inatmospheric environment (the temperature is from 400°C to 900°C) the oxidation resistance of diamond thin films was investigated. The results indicate that under the atmospheric environment diamond thin film surface morphology did not change after 6 hours at 400°C. Diamond thin film surface morphology began to change after 2 hours at 600°C, and when time was extended to 4 hours, the diamond thin film surface morphology changed significantly. The surface morphology of diamond films began to change after 15 minutes at a 700°C condition and when time was extended to 6 hours diamond films were all destroyed. All the diamond films on the silicon substrate disappeared completely in 20 minutes at 900°C. The intact crystal face is the reason that natural diamond has stable chemical property. The crystal face of synthetic diamond film has a lot of defects, especially on the side. Oxidation of the diamond films begin with the grain boundary and defects.

  2. Oscillatory wear tests of dental composites.

    PubMed

    Pilliar, R M; Smith, D C; Maric, B

    1984-09-01

    The wear behavior of 12 commercial restorative composites (conventional and microfilled) and an unfilled restorative material was evaluated using an in vitro wear test referred to as an oscillatory wear test. The effect of varying test conditions was evaluated in a series of preliminary experiments in order to define test conditions for material evaluation. The materials were tested after being aged in water at 37 degrees C for periods of from seven days to one year. The results indicated consistently lower wear rates for the microfilled materials as compared with those of the conventional composites. Aging did not result in significant differences in wear rates measured by this method. Scanning electron micrography of worn surfaces suggested a possible effect of filler particle shape and bonding to the matrix to explain this difference. Although the relevance of the results to clinical behavior is not yet known, the study indicated the importance of material variables on wear.

  3. Surface Wear Measurement Using Optical Correlation Technique

    NASA Astrophysics Data System (ADS)

    Acinger, Kresimir

    1983-12-01

    The coherent optical correlation technique was applied for measuring the surface wear of a tappet (part of car engine), worn by friction with the camshaft. It was found that maximum correlation intensity decays exponentially with the number of wear cycles (i.e. camshaft revolutions). Tappets of the same make have an identical rate of correlation decay. Tappets of different makes have different rates of correlation decay which are in agreement with observed long term wear.

  4. Diamond Nanophotonics and Quantum Optics

    NASA Astrophysics Data System (ADS)

    Barclay, Paul

    2011-10-01

    The diamond nitrogen-vacancy (NV) center is an optically active impurity whose ``atom-like'' properties make it a promising solid state qubit, in which well-defined optical transitions are used to control the quantum state of single NV electron and nuclear spins. These properties have led to impressive demonstrations of quantum information storage in single NV nuclear spins, entanglement between NV electron spins and single photons, and implementations of high resolution optical magnetometers using single NVs. A missing ingredient for implementing quantum information processing architectures with NVs is creating scalable coherent coupling between them. Nanophotonic circuits, in which waveguides function as a ``quantum bus'' between NVs embedded in optical microcavities, offer a chip-based solution to this hurdle. In my talk I will review recent advances in realizing nanophotonic devices in diamond based materials. I will present results demonstrating Purcell enhanced coupling between optical nanocavities and NVs in single crystal diamond, and will discuss opportunities and challenges which lay ahead for diamond quantum optics.

  5. Plasma boriding of a cobalt-chromium alloy as an interlayer for nanostructured diamond growth

    NASA Astrophysics Data System (ADS)

    Johnston, Jamin M.; Jubinsky, Matthew; Catledge, Shane A.

    2015-02-01

    Chemical vapor deposited (CVD) diamond coatings can potentially improve the wear resistance of cobalt-chromium medical implant surfaces, but the high cobalt content in these alloys acts as a catalyst to form graphitic carbon. Boriding by high temperature liquid baths and powder packing has been shown to improve CVD diamond compatibility with cobalt alloys. We use the microwave plasma-enhanced (PE) CVD process to deposit interlayers composed primarily of the borides of cobalt and chromium. The use of diborane (B2H6) in the plasma feedgas allows for the formation of a robust boride interlayer for suppressing graphitic carbon during subsequent CVD of nano-structured diamond (NSD). This metal-boride interlayer is shown to be an effective diffusion barrier against elemental cobalt for improving nucleation and adhesion of NSD coatings on a CoCrMo alloy. Migration of elemental cobalt to the surface of the interlayer is significantly reduced and undetectable on the surface of the subsequently-grown NSD coating. The effects of PECVD boriding are compared for a range of substrate temperatures and deposition times and are evaluated using glancing-angle X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and micro-Raman spectroscopy. Boriding of CoCrMo results in adhered nanostructured diamond coatings with low surface roughness.

  6. Volumetric wear of various orthotic appliance materials.

    PubMed

    Issar-Grill, Noana; Roberts, Howard W; Wright, Edward F; Dixon, Sara A; Vandewalle, Kraig S

    2013-10-01

    The purpose of this study was to compare the resistance to wear of six commonly used orthotic appliance materials. These materials were: SR Ivocap (Ivoclar Vivadent, Inc., Amherst, NY), Eclipse (Dentsply International, York, PA), ProBase (Ivoclar Vivadent), Valplast (Valplast International Corp., Oceanside, NY), Impak (CMP Industries LLC, Albany, NY), and Clearsplint (Astron Dental Corp., Lake Zurich, IL). Twelve cylindrical specimens of each material were fabricated per manufacturer instructions. Occlusal wear was simulated in a custom-made wear simulator with each specimen receiving four wear scars in a two-body wear simulation using a 1.5 mm tungsten-carbide tipped stylus at 40 newtons for 2500 cycles at 1 Hz, while immersed in 37 degrees C distilled water (n = 48). The specimens were evaluated before and after wear testing using a three-dimensional (3D) noncontact profilometer (Proscan 2000, Scantron Corp., Eagan, MN). A mean change in volume was determined for each orthotic material. Results found that Clearsplint material displayed the greatest amount of volume loss/wear, while SR Ivocap, Eclipse, and ProBase materials had the least amount of wear. Valplast and Impak performed more moderately. Based upon this wear knowledge, practitioners are able to more reliably choose the appliance material necessary for their various patients. PMID:24308100

  7. Wear Performance of Laser Processed Tantalum Coatings

    PubMed Central

    Dittrick, Stanley; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    This first generation investigation evaluates the in vitro tribological performance of laser-processed Ta coatings on Ti for load-bearing implant applications. Linear reciprocating wear tests in simulated body fluid showed one order of magnitude less wear rate, of the order of 10−4mm3(N.m)−1, for Ta coatings compared to Ti. Our results demonstrate that Ta coatings can potentially minimize the early-stage bone-implant interface micro-motion induced wear debris generation due to their excellent bioactivity comparable to that of hydroxyapatite (HA), high wear resistance and toughness compared to popular HA coatings. PMID:22058608

  8. Predicting and preventing casing wear while drilling

    SciTech Connect

    Perdue, J.M.

    1998-06-01

    Drillpipe rotating inside a well`s intermediate string of casing has long been recognized as the principal cause of internal casing wear. Because today`s wells are longer and deeper than ever, prolonged contact can cause sufficient wear to either breach the casing or weaken it to the extent that it will rupture when the casing is pressure tested, delaying the project while an unplanned tieback casing string is installed. Based on more than 300 casing wear experiments, a computer program was developed to calculate the potential for casing wear during drilling operations. Taking proper precautions can save operators more than $1 million per well.

  9. Diamond Powders Less Than 100 nm in Diameter as Effective Solid Lubricants in Vacuum

    NASA Astrophysics Data System (ADS)

    Gubarevich, Anna Valeryevna; Usuba, Shu; Kakudate, Yozo; Tanaka, Akihiro; Odawara, Osamu

    2004-07-01

    The frictional behavior of detonation nanodiamond and single-crystal fine diamond powders were studied to determine the effect of particle diameter on their lubricative and abrasive characteristics. In vacuum, nanodiamond with an average aggregate size of 75 nm and mechanically crushed single-crystal diamond powders with an average diameter of 50 nm formed a uniform lubricating layer while sliding against a SiC ball and showed very low friction coefficients of 0.03 and less than 0.01, respectively, under moderate conditions of 0.5 N applied load and 3.5 mm/s sliding speed. A clear tendency was observed for both the friction coefficient and specific wear rates to decrease with decreasing particle/aggregate size.

  10. Synthesis and tribological properties of diamond-like carbon films by electrochemical anode deposition

    NASA Astrophysics Data System (ADS)

    Li, Yang; Zhang, GuiFeng; Hou, XiaoDuo; Deng, DeWei

    2012-06-01

    Diamond-like carbon films (DLC) are deposited on Ti substrate by electrochemical anodic deposition at room temperature in pure methanol solution using a pulsed DC voltage at a range from 200 V to 2000 V. Raman spectroscopy analysis of the films reveals two broaden characteristic absorption peaks centred at ˜1350 cm-1 and 1580 cm-1, relating to D- and G-band of typical DLC films, respectively. A broad peak centred at 1325-1330 cm-1 is observed when an applied potential is 1200 V, which can confirm that the deposited films contained diamond structure phase. Tribological properties of the coated Ti substrates have been measured by means of a ball-on-plate wear test machine. A related growth mechanism of DLC films by the anodic deposition mode has also been discussed.

  11. Diamond/diamond-like carbon coated nanotube structures for efficient electron field emission

    NASA Technical Reports Server (NTRS)

    Dimitrijevic, Steven (Inventor); Withers, James C. (Inventor); Loutfy, Raouf O. (Inventor)

    2005-01-01

    The present invention is directed to a nanotube coated with diamond or diamond-like carbon, a field emitter cathode comprising same, and a field emitter comprising the cathode. It is also directed to a method of preventing the evaporation of carbon from a field emitter comprising a cathode comprised of nanotubes by coating the nanotube with diamond or diamond-like carbon. In another aspect, the present invention is directed to a method of preventing the evaporation of carbon from an electron field emitter comprising a cathode comprised of nanotubes, which method comprises coating the nanotubes with diamond or diamond-like carbon.

  12. Diamond-like carbon films for polyethylene femoral parts: Raman and FT-IR spectroscopy before and after incubation in simulated body liquid.

    PubMed

    Dorner-Reisel, A; Gärtner, G; Reisel, G; Irmer, G

    2008-03-01

    In artificial prosthetics for knee, hip, finger or shoulder joints, ultrahigh molecular weight polyethylene (UHMW-PE) is a significant material. Several attempts to reduce the wear rate of UHMW-PE, i.e. the application of suitable coatings, are in progress. A surface modification of polyethylene with wear-resistant hydrogenated diamond-like carbon is favourable, owing to the chemical similarity of polyethylene (-C-H(2)-)(n) and C:H or amorphous C:H (a-C:H) coatings with diamond-like properties. In the present study, the microstructure of a-C:H coatings on UHMW-PE substrates was investigated by Raman and Fourier transform infrared (FT-IR) spectroscopy. FT-IR spectroscopy shows very broad absorption lines, which point to the disorder and diversity of different symmetric, asymmetric aromatic, olefin sp(2)-hybridized or sp(3)-hybridized C-H groups in the amorphous diamond-like carbon coating. Following a long incubation of 12 months in a simulated body liquid, the structural investigations were repeated. Furthermore, fractured cross-sections and the wetting behaviour with polar liquids were examined. After incubation in simulated body liquid, Raman spectroscopy pointed to a reduction of the C-H bonds in the diamond-like carbon coatings. On the basis of these findings, one can conclude that hydrogenated diamond-like carbon is able to interact with salt solutions by substituting the hydrogen with appropriate ions. PMID:18157668

  13. Comparison of wear of ultra-high molecular weight polyethylene acetabular cups against surface-engineered femoral heads.

    PubMed

    Galvin, A; Brockett, C; Williams, S; Hatto, P; Burton, A; Isaac, G; Stone, M; Ingham, E; Fisher, J

    2008-10-01

    Alumina ceramic heads have been previously shown to reduce polyethylene wear in comparison to cobalt chrome (CoCr) heads in artificial hip joints. However, there are concerns about the brittle nature of ceramics. It is therefore of interest to investigate ceramic-like coatings on metallic heads. The aim of this study was to compare the friction and wear of ultra-high molecular weight polyethylene (UHMWPE) against alumina ceramic, CoCr, and surface-engineered ceramic-like coatings in a friction simulator and a hip joint simulator. All femoral heads tested were 28 mm diameter and included: Biolox Forte alumina, CoCr, arc evaporative physical vapour deposition (AEPVD) chromium nitride (CrN) coated CoCr, plasma-assisted chemical vapour deposition (PACVD) amorphous diamond-like carbon (aDLC) coated CoCr, sputter CrN coated CoCr, reactive gas controlled arc (RGCA) AEPVD titanium nitride (TiN) coated CoCr, and Graphit-iC coated CoCr. These were articulated against UHMWPE acetabular cups in a friction simulator and a hip joint simulator. Alumina and CoCr gave the lowest wear volumes whereas the sputter coated CrN gave the highest. Alumina also had the lowest friction factor. There was an association between surface parameters and wear. This study indicates that surface topography of surface-engineered femoral heads is more important than friction and wettability in controlling UHMWPE wear.

  14. Fault Wear and Friction Evolution: Experimental Analysis

    NASA Astrophysics Data System (ADS)

    Boneh, Y.; Chang, J. C.; Lockner, D. A.; Reches, Z.

    2011-12-01

    Wear is an inevitable product of frictional sliding of brittle rocks as evidenced by the ubiquitous occurrence of fault gouge and slickenside striations. We present here experimental observations designed to demonstrate the relationship between wear and friction and their governing mechanisms. The experiments were conducted with a rotary shear apparatus on solid, ring-shaped rock samples that slipped for displacements up to tens of meters. Stresses, wear and temperature were continuously monitored. We analyzed 86 experiments of Kasota dolomite, Sierra White granite, Pennsylvania quartzite, Karoo gabbro, and Tennessee sandstone at slip velocities ranging from 0.002 to 0.97 m/s, and normal stress from 0.25 to 6.9 MPa. We conducted two types of runs: short slip experiments (slip distance < 25 mm) primarily on fresh, surface-ground samples, designed to analyze initial wear mechanisms; and long slip experiments (slip distance > 3 m) designed to achieve mature wear conditions and to observe the evolution of wear and friction as the fault surfaces evolved. The experiments reveal three wear stages: initial, running-in, and steady-state. The initial stage is characterized by (1) discrete damage striations, the length of which is comparable to total slip , and local pits or plow features; (2) timing and magnitude of fault-normal dilation corresponds to transient changes of normal and shear stresses; and (3) surface roughness increasing with the applied normal stress. We interpret these observations as wear mechanisms of (a) plowing into the fresh rock surfaces; (b) asperity breakage; and (c) asperity climb. The running-in stage is characterized by (1) intense wear-rate over a critical wear distance of Rd = 0.3-2 m; (2) drop of friction coefficient over a weakening distance of Dc = 0.2-4 m; (3) Rd and Dc display positive, quasi-linear relation with each other. We interpret these observations as indicating the organizing of newly-created wear particles into a 'three

  15. The mechanical properties of various chemical vapor deposition diamond structures compared to the ideal single crystal

    NASA Astrophysics Data System (ADS)

    Hess, Peter

    2012-03-01

    , fracture is studied mainly by indentation or mechanical breaking of freestanding films, e.g., by bending or bursting. It is very difficult to study the fracture mechanism, discriminating between tensile, shear, and tearing stress components (mode I-III fracture) with these partly semiquantitative methods. A novel ultrasonic laser-based technique using short nonlinear surface acoustic wave pulses, developing shock fronts during propagation, has recently been employed to study mode-resolved fractures of single-crystal silicon. This method allows the generation of finite cracks and the evaluation of the fracture strength for well-defined crystallographic configurations. Laser ultrasonics reaches the critical stress at which real diamond fails and therefore can be employed as a new tool for mechanistic studies of the fracture behavior of CVD diamond in the future.

  16. Wear of highly crosslinked polyethylene acetabular components

    PubMed Central

    Callary, Stuart A; Solomon, Lucian B; Holubowycz, Oksana T; Campbell, David G; Munn, Zachary; Howie, Donald W

    2015-01-01

    Background and purpose Wear rates of highly crosslinked polyethylene (XLPE) acetabular components have varied considerably between different published studies. This variation is in part due to the different techniques used to measure wear and to the errors inherent in measuring the relatively low amounts of wear in XLPE bearings. We undertook a scoping review of studies that have examined the in vivo wear of XLPE acetabular components using the most sensitive method available, radiostereometric analysis (RSA). Methods A systematic search of the PubMed, Scopus, and Cochrane databases was performed to identify published studies in which RSA was used to measure wear of XLPE components in primary total hip arthroplasty (THA). Results 18 publications examined 12 primary THA cohorts, comprising only 260 THAs at 2–10 years of follow-up. The mean or median proximal wear rate reported ranged from 0.00 to 0.06 mm/year. However, differences in the manner in which wear was determined made it difficult to compare some studies. Furthermore, differences in RSA methodology between studies, such as the use of supine or standing radiographs and the use of beaded or unbeaded reference segments, may limit future meta-analyses examining the effect of patient and implant variables on wear rates. Interpretation This scoping review confirmed the low wear rates of XLPE in THA, as measured by RSA. We make recommendations to enhance the standardization of reporting of RSA wear results, which will facilitate early identification of poorly performing implants and enable a better understanding of the effects of surgical and patient factors on wear. PMID:25301435

  17. Optical and tribological properties of diamond-like carbon films synthesized by plasma immersion ion processing

    SciTech Connect

    He, X-M.; Walter, K.C.; Bardeau, J-F.; Nastasi, M.; Lee, S-T.; Sun, X.S.

    1999-04-12

    Hard diamond-like carbon (DLC) films have been prepared on PMMA (Polymethyl methacrylate), glass, and Si(100) substrates using C{sub 2}H{sub 2}-Ar plasma immersion ion processing (PIIP). The composition, structure, and properties of the films were investigated with regard to variation of the deposition parameters. It was found that the modulation of reactive gas composition during PIIP could enhance the formation of DLC films with an increased sp{sup 3} bonding structure, improved surface smoothness, high density and high hardness. An optimal combination of good optical properties and high hardness was highly dependent on the control of hydrogen content in the DLC films. Tribological tests showed that DLC-coated glass and PMMA samples exhibited a reduced friction coefficient and enhanced wear resistance relative to uncoated glass and PMMA materials. The effects of ion energy and gas composition during PIIP deposition on the formation of optically transparent and wear resistant DLC films are discussed.

  18. Medical applications of diamond particles and surfaces.

    SciTech Connect

    Narayan, R. J.; Boehm, R. D.; Sumant, A. V.

    2011-04-01

    Diamond has been considered for use in several medical applications due to its unique mechanical, chemical, optical, and biological properties. In this paper, methods for preparing synthetic diamond surfaces and particles are described. In addition, recent developments involving the use of diamond in prostheses, sensing, imaging, and drug delivery applications are reviewed. These developments suggest that diamond-containing structures will provide significant improvements in the diagnosis and treatment of medical conditions over the coming years. Diamond is an allotrope of carbon that is being considered for use in several medical applications. Ramachandran determined that the crystal structure of diamond consists of two close packed interpenetrating face centered cubic lattices; one lattice is shifted with respect to the other along the elemental cube space diagonal by one-quarter of its length. If one approximates carbon atoms as equal diameter rigid spheres, the filling of this construction is 34%. Due to the carbon-carbon distance (1.54 {angstrom}), diamond crystal exhibits the highest atomic density (1.76 x 10{sup 23} cm{sup -3}) of any solid. The very high bond energy between two carbon atoms (83 kcal/mol) and the directionality of tetrahedral bonds are the main reasons for the high strength of diamond. Diamond demonstrates the highest Vickers hardness value of any material (10,000 kg/mm{sup 2}). The tribological properties of diamond are also impressive; the coefficient of friction of polished diamond is 0.07 in argon and 0.05 in humid air. Diamond is resistant to corrosion except in an oxygen atmosphere at temperatures over 800 C. In addition, type IIa diamond exhibits the highest thermal conductivity of all materials (20 W cm{sup -1} K{sup -1} at room temperature).

  19. Synthesizing Diamond from Liquid Feedstock

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua

    2005-01-01

    A relatively economical method of chemical vapor deposition (CVD) has been developed for synthesizing diamond crystals and films. Unlike prior CVD methods for synthesizing diamond, this method does not require precisely proportioned flows of compressed gas feedstocks or the use of electrical discharges to decompose the feedstocks to obtain free radicals needed for deposition chemical reactions. Instead, the feedstocks used in this method are mixtures of common organic liquids that can be prepared in advance, and decomposition of feedstock vapors is effected simply by heating. The feedstock used in this method is a solution comprising between 90 and 99 weight percent of methanol and the balance of one or more other oxyhydrocarbons that could include ethanol, isopropanol, and/or acetone. This mixture of compounds is chosen so that dissociation of molecules results in the desired proportions of carbon-containing radicals (principally, CH3) and of OH, H, and O radicals. Undesirably, the CVD temperature and pressure conditions thermodynamically favor the growth of graphite over the growth of diamond. The H radicals are desirable because they help to stabilize the growing surface of diamond by shifting the thermodynamic balance toward favoring the growth of diamond. The OH and O radicals are desirable because they preferentially etch graphite and other non-diamond carbon, thereby helping to ensure the net deposition of pure diamond. The non-methanol compounds are included in the solution because (1) methanol contains equal numbers of C and O atoms; (2) an excess of C over O is needed to obtain net deposition of diamond; and (3) the non-methanol molecules contain multiple carbon atoms for each oxygen atom and thus supply the needed excess carbon A typical apparatus used in this method includes a reservoir containing the feedstock liquid and a partially evacuated stainless-steel reaction chamber. The reservoir is connected to the chamber via tubing and a needle valve or

  20. 33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation and Navigable... Areas § 110.6 Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). Beginning at the southeasterly corner of the wharf, at the most southerly point of Great Diamond Island...

  1. 33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation and Navigable... Areas § 110.6 Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). Beginning at the southeasterly corner of the wharf, at the most southerly point of Great Diamond Island...

  2. 33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation and Navigable... Areas § 110.6 Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). Beginning at the southeasterly corner of the wharf, at the most southerly point of Great Diamond Island...

  3. 33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation and Navigable... Areas § 110.6 Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). Beginning at the southeasterly corner of the wharf, at the most southerly point of Great Diamond Island...

  4. 33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation and Navigable... Areas § 110.6 Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). Beginning at the southeasterly corner of the wharf, at the most southerly point of Great Diamond Island...

  5. Boron doped diamond biotechnology: from sensors to neurointerfaces.

    PubMed

    Hébert, C; Scorsone, E; Bendali, A; Kiran, R; Cottance, M; Girard, H A; Degardin, J; Dubus, E; Lissorgues, G; Rousseau, L; Mailley, P; Picaud, S; Bergonzo, P

    2014-01-01

    Boron doped nanocrystalline diamond is known as a remarkable material for the fabrication of sensors, taking advantage of its biocompatibility, electrochemical properties, and stability. Sensors can be fabricated to directly probe physiological species from biofluids (e.g. blood or urine), as will be presented. In collaboration with electrophysiologists and biologists, the technology was adapted to enable structured diamond devices such as microelectrode arrays (MEAs), i.e. common electrophysiology tools, to probe neuronal activity distributed over large populations of neurons or embryonic organs. Specific MEAs can also be used to build neural prostheses or implants to compensate function losses due to lesions or degeneration of parts of the central nervous system, such as retinal implants, which exhibit real promise as biocompatible neuroprostheses for in vivo neuronal stimulations. New electrode geometries enable high performance electrodes to surpass more conventional materials for such applications.

  6. Role of third bodies in friction and wear of protective coatings

    NASA Astrophysics Data System (ADS)

    Singer, I. L.; Dvorak, S. D.; Wahl, K. J.; Scharf, T. W.

    2003-09-01

    The literature on protective tribological coatings often focuses on correlations with measurable coating properties (composition, structure, and mechanical) but ignores the mechanisms of friction and wear. In fact, long-lived coatings often survive because of third bodies that form inside the moving contact. This article reviews earlier studies of third body processes carried out by mainly ex situ methods and reports more recent studies investigating third body processes using in situ techniques. Direct evidence that third bodies control friction and wear processes has been obtained with a tribometer incorporating in situ optical microscopy and Raman spectroscopy. Videotapes and Raman spectra of the sliding contact were recorded during reciprocating sliding tests performed in both dry and humid air with transparent hemispheres (glass or sapphire). Third body processes were correlated directly to friction and wear behavior of three low friction coatings: amorphous Pb-Mo-S diamond-like carbon (DLC); and annealed boron carbide. In all three cases, the friction behavior could be explained in terms of the relative motion between a transfer film on the hemisphere and the wear track. With amorphous Pb-Mo-S, the transfer film was MoS2; with DLC, it was a graphite-like carbon; and with annealed boron carbide, it was either a mix of H3BO3 and carbon (at μ=0.08) or, when the H3BO3 wore away, carbon alone (at μ=0.2). Friction rises with Pb-Mo-S and DLC in humid air were ascribed to a change in interfacial shear strength; friction spikes and fluctuations with DLC were associated with periodic loss of transfer film thickness. For all three coatings, interfacial sliding between transfer film and wear track on coating was the dominant velocity accommodation mode.

  7. Astronaut James Buchli wearing extravehicular mobility unit

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Astronaut James F. Buchli, wearing an extravehicular mobility unit (EMU), is about to be submerged in the weightless environment training facility (WETF) to simulate a contingency extravehicular activity (EVA) for STS 61-A. In this portrait view, Buchli is wearing a communications carrier assembly (CCA).

  8. Friction, wear, and lubrication in vacuum

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1971-01-01

    A review of studies and observations on the friction, wear, and lubrication behavior of materials in a vacuum environment is presented. The factors that determine and influence friction and wear are discussed. They include topographical, physical, mechanical, and the chemical nature of the surface. The effects of bulk properties such as deformation characteristics, fracture behavior, and structure are included.

  9. Diamond-like nanocomposite coatings for LIGA-fabricated nickel alloy parts.

    SciTech Connect

    Prasad, Somuri V.; Scharf, Thomas W.

    2005-03-01

    A commercial plasma enhanced chemical vapor deposition (PECVD) technique with planetary substrate rotation was used to apply a thin (200-400 nm thick) conformal diamond-like carbon (DLC) coating (known as a diamond-like nanocomposite (DLN)) on LIGA fabricated Ni-Mn alloy parts. The PECVD technique is known to overcome the drawbacks associated with the line-of-sight nature of physical vapor deposition (PVD) and substrate heating inherent with traditional chemical vapor deposition (CVD). The purpose of the present study is to characterize the coverage, adhesion, and tribological (friction and wear) behavior of DLN coatings applied to planar and sidewall surfaces of small featured LIGA Ni-Mn fabricated parts, e.g. 280 {micro}m thick sidewalls. Friction and wear tests were performed in dry nitrogen, dry air, and air with 50% RH at Hertzian contact pressures ranging from 0.3 to 0.6 GPa. The friction coefficient of bare Ni-Mn alloy was determined to be 0.9. In contrast, low friction coefficients ({approx}0.02 in dry nitrogen and {approx}0.2 in 50% RH air) and minimal amount of wear were exhibited for the DLN coated LIGA Ni-Mn alloy parts and test coupons. This behavior was due to the ability of the coating to transfer to the rubbing counterface providing low interfacial shear at the sliding contact; resultantly, coating one surface was adequate for low friction and wear. In addition, a 30 nm thick titanium bond layer was determined to be necessary for good adhesion of DLN coating to Ni-Mn alloy substrates. Raman spectroscopy and cross-sectional SEM with energy dispersive x-ray analysis revealed that the DLN coatings deposited by the PECVD with planetary substrate rotation covered both the planar and sidewall surfaces of LIGA fabricated parts, as well as narrow holes of 300 {micro}m (0.012 inch) diameter.

  10. Optimizing the Growth of (111) Diamond for Diamond Based Magnetometry

    NASA Astrophysics Data System (ADS)

    Kamp, Eric; Godwin, Patrick; Samarth, Nitin; Snyder, David; de Las Casas, Charles; Awschalom, David D.

    Magnetometers based on nitrogen vacancy (NV) ensembles have recently achieved sub-picotesla sensitivities [Phys. Rev. X 5, 041001(2015)], putting the technique on par with SQUID and MFM magnetometry.Typically these sensors use (100) oriented diamond with NV centers forming along all four (111) crystal orientations.This allows for vector magnetometry, but is a hindrance to the absolute sensitivity. Diamond grown on (111) oriented substrates through microwave plasma enhanced chemical vapor deposition(MP-CVD) provides a promising route in this context since such films can exhibit preferential orientation greater than 99% [Appl. Phys. Lett.104, 102407 (2014)]. An important challenge though is to achieve sufficiently high NV center densities required for enhancing the sensitivity of an NV ensemble magnetometer.We report systematic studies of the MP-CVD growth and characterization of (111) oriented diamond, where we vary growth temperature, methane concentration, and nitrogen doping. For each film we study the Nitrogen to NV ratio, the NV- to NV0 ratio, and alignment percentage to minimize sources of decoherence and ensure preferential alignment. From these measurements we determine the optimal growth parameters for high sensitivity, NV center ensemble scalar magnetometry. Funded by NSF-DMR.

  11. Treating orthopedic prosthesis with diamond-like carbon: minimizing debris in Ti6Al4V.

    PubMed

    Oliveira, Luciane Y S; Kuromoto, Neide K; Siqueira, Carlos J M

    2014-10-01

    Prostheses are subject to various forms of failing mechanisms, including wear from ordinary patient motion. Superficial treatments can improve tribological properties of the contact pair, minimizing wear and increasing prostheses lifetime. One possibility is the diamond-like carbon (DLC) coating, where Carbon is deposited with variable ratio of sp(2)/sp(3) structures, leading to an increase in surface hardness. So in this research Ti6Al4V samples were coated with DLC using sputtering process to evaluate the debris release. The Ti6Al4V and Ti6Al4V plus DLC coating surfaces were analyzed using Raman spectroscopy and instrumented indentation (hardness). The wear behavior was tested using a reciprocating linear tribometer. The wear rate was smaller in the coated samples, producing less debris than the untreated Ti6Al4V alloy. Debris morphology was also evaluated, using scanning electronic microscopy, and it was observed that debris size from the coated samples were bigger than those observed from the uncoated Ti6Al4V alloy, above the size that generally triggers biological response from the host. PMID:24948374

  12. Wear mechanisms of partially stabilized zirconia

    SciTech Connect

    Aronov, V.

    1987-01-01

    This paper is devoted to an investigation of the wear mechanisms of magnesia and yttria partially-stabilized zirconia in ceramic/ceramic and ceramic/metal sliding-contact tribological systems at high temperature. It was found that the wear of ceramics rubbed against ceramics at room temperature may be attributed to intensive plastic deformation of surfaces resulting in low cycle fatigue. The wear mechanism of ceramics rubbed against metals was by polishing and surface fracture, while that of metals was adhesive transfer of material on to ceramic surfaces. Investigation of the wear behavior of magnesia partially-stabilized zirconia rubbed against itself showed that up to three orders of magnitude increase in wear resistance can be achieved in a particular temperature range, depending on both sliding speed and the ambient temperature. XRD analysis revealed that a thermally-induced phase transformation takes place on the frictional interface.

  13. Modeling wear of cast Ti alloys

    PubMed Central

    Chan, Kwai S.; Koike, Marie; Okabe, Toru

    2007-01-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic–plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an α, α+β or β microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability. PMID:17224314

  14. Wear simulation effects on overdenture stud attachments.

    PubMed

    Rutkunas, Vygandas; Mizutani, Hiroshi; Takahashi, Hidekazu; Iwasaki, Naohiko

    2011-01-01

    The aim of this study was to evaluate wear effects on overdenture resilient attachments. Six commercially available attachments were investigated: ERA orange and white (EO and EW), Locator pink, white and blue (LRP, LRW and LRB) and OP anchor (OP). Five specimens were used for wear simulation while other two specimens served as controls. Fifteen thousands insertion-removal cycles were simulated. Dimensional changes and surface characteristics were evaluated using light microscopy and SEM, respectively. Sudden decrease of retentive force was characteristic for EO and EW attachments. Retentive force of Locator attachments fluctuated throughout the wear simulation period. Dimensional changes and surface wear was more expressed on plastic cores than on plastic rings of attachment males. Based on SEM analysis, some of the specimens obtained smoother surface after wear simulation. Mechanism of retention loss of resilient overdenture attachments can be only partially explained by dimensional changes and surface alterations.

  15. Biologically Based Restorative Management of Tooth Wear

    PubMed Central

    Kelleher, Martin G. D.; Bomfim, Deborah I.; Austin, Rupert S.

    2012-01-01

    The prevalence and severity of tooth wear is increasing in industrialised nations. Yet, there is no high-level evidence to support or refute any therapeutic intervention. In the absence of such evidence, many currently prevailing management strategies for tooth wear may be failing in their duty of care to first and foremost improve the oral health of patients with this disease. This paper promotes biologically sound approaches to the management of tooth wear on the basis of current best evidence of the aetiology and clinical features of this disease. The relative risks and benefits of the varying approaches to managing tooth wear are discussed with reference to long-term follow-up studies. Using reference to ethical standards such as “The Daughter Test”, this paper presents case reports of patients with moderate-to-severe levels of tooth wear managed in line with these biologically sound principles. PMID:22315608

  16. Friction, wear, transfer and wear surface morphology of ultra-high-molecular-weight polyethylene

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1983-01-01

    Tribological studies at 25 C in a 50-percent-relative-humidity air atmosphere were conducted using hemispherically tipped 440 C HT (high temperature) stainless steel pins sliding against ultra-high-molecular-weight polyethylene (UHMWPE) disks. The results indicate that sliding speed, sliding distance, contact stress and specimen geometry can markedly affect friction, UHMWPE wear, UHMWPE transfer and the type of wear mechanisms that occur. Adhesion appears to be the predominant wear mechanism; but after long sliding distances at slow speeds, heavy ridges of transfer result which can induce fatigue-like wear on the UHMWPE disk wear track. In one instance, abrasive wear to the metallic pin was observed. This was caused by a hard particle embedded in the UHMWPE disk wear track.

  17. Friction, wear, transfer, and wear surface morphology of ultrahigh-molecular-weight polyethylene

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1985-01-01

    Tribological studies at 25 C in a 50-percent-relative-humidity air atmosphere were conducted using hemispherically tipped 440 C HT (high temperature) stainless steel pins sliding against ultra-high-molecular-weight polyethylene (UHMWPE) disks. The results indicate that sliding speed, sliding distance, contact stress and specimen geometry can markedly affect friction, UHMWPE wear, UHMWPE transfer and the type of wear mechanisms that occur. Adhesion appears to be the predominant wear mechanism; but after long sliding distances at slow speeds, heavy ridges of transfer result which can induce fatigue-like wear on the UHMWPE disk wear track. In one instance, abrasive wear to the metallic pin was observed. This was caused by a hard particle embedded in the UHMWPE disk wear track.

  18. Chemical vapor deposited diamond-on-diamond powder composites (LDRD final report)

    SciTech Connect

    Panitz, J.K.; Hsu, W.L.; Tallant, D.R.; McMaster, M.; Fox, C.; Staley, D.

    1995-12-01

    Densifying non-mined diamond powder precursors with diamond produced by chemical vapor infiltration (CVI) is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chemical vapor deposition (CVD) processes. The authors developed techniques for forming diamond powder precursors and densified these precursors in a hot filament-assisted reactor and a microwave plasma-assisted reactor. Densification conditions were varied following a fractional factorial statistical design. A number of conclusions can be drawn as a result of this study. High density diamond powder green bodies that contain a mixture of particle sizes solidify more readily than more porous diamond powder green bodies with narrow distributions of particle sizes. No composite was completely densified although all of the deposits were densified to some degree. The hot filament-assisted reactor deposited more material below the exterior surface, in the interior of the powder deposits; in contrast, the microwave-assisted reactor tended to deposit a CVD diamond skin over the top of the powder precursors which inhibited vapor phase diamond growth in the interior of the powder deposits. There were subtle variations in diamond quality as a function of the CVI process parameters. Diamond and glassy carbon tended to form at the exterior surface of the composites directly exposed to either the hot filament or the microwave plasma. However, in the interior, e.g. the powder/substrate interface, diamond plus diamond-like-carbon formed. All of the diamond composites produced were grey and relatively opaque because they contained flawed diamond, diamond-like-carbon and glassy carbon. A large amount of flawed and non-diamond material could be removed by post-CVI oxygen heat treatments. Heat treatments in oxygen changed the color of the composites to white.

  19. Laser damage threshold of diamond films

    NASA Technical Reports Server (NTRS)

    Albin, Sacharia; Cropper, Andre D.; Watkins, Linwood C.; Byvik, Charles E.; Buoncristiani, A. Martin

    1989-01-01

    The possibility that diamond films may inhibit laser-induced damage to optical components in laser systems films was investigated by measuring laser damage thresholds of free-standing diamond film windows, diamond films deposited on silicon substrates, and bare silicon substrate. Polycrystalline diamond films were deposited using a dc plasma-enhanced CVD process. It was found that free-standing diamond films had the highest laser damage threshold at 1064 nm. For a diamond film of 630 nm, the damage threshold was found to be 7 J/sq cm, as compared to a damage threshold of 4.5 J/sq cm for bare silicon, and a low value of 1.5 J/sq cm for the film/substrate combination. The damage mechanism is considered to involve melting or dielectric breakdown induced by laser radiation. The low value of the film/substrate combination is attributed to film stress and conditions of film deposition.

  20. Epitaxial growth of europium monoxide on diamond

    SciTech Connect

    Melville, A.; Heeg, T.; Mairoser, T.; Schmehl, A.; Fischer, M.; Gsell, S.; Schreck, M.; Awschalom, D. D.; Holländer, B.; Schubert, J.; Schlom, D. G.

    2013-11-25

    We report the epitaxial integration of phase-pure EuO on both single-crystal diamond and on epitaxial diamond films grown on silicon utilizing reactive molecular-beam epitaxy. The epitaxial orientation relationship is (001) EuO ‖ (001) diamond and [110] EuO ‖[100] diamond. The EuO layer is nominally unstrained and ferromagnetic with a transition temperature of 68 ± 2 K and a saturation magnetization of 5.5 ± 0.1 Bohr magnetons per europium ion on the single-crystal diamond, and a transition temperature of 67 ± 2 K and a saturation magnetization of 2.1 ± 0.1 Bohr magnetons per europium ion on the epitaxial diamond film.