Science.gov

Sample records for diamond tool wear

  1. Diamond Tool Wear Vs. Cutting Distance On Electroless Nickel Mirrors

    NASA Astrophysics Data System (ADS)

    Syn, C. K.; Taylor, J. S.; Donaldson, R. R.

    1987-02-01

    Wear data are presented for diamond tools cutting electroless nickel (eNi) for cut lengths up to 70,000 ft (13 miles). Two tools having different infrared absorption characteristics were used to cut an eNi preparation that had yielded minimum values for surface roughness and tool wear rate in a previous study. The data include Talystep measurement of the rms amplitude of the feed-marks versus cumulative cutting distance, representative examples of shape changes for the feed-mark profiles, SEM and optical micrographs of the tool rake and flank face wear zones, and measurements of the cutting edge profile and edge recession distance by a tool-nose replication technique. Feed-mark roughness values were found to increase from 5 to 90 A rms over the duration of the test, with an associated edge recession of about 1000 A and the development of a periodic tool edge grooving indicative of burnishing of the part surface. The IR absorption data successfully predicted the order of the two tools in terms of wear rate and fracture toughness.

  2. Diamond tool wear vs cutting distance on electroless nickel mirrors

    SciTech Connect

    Syn, C.K.; Taylor, J.S.; Donaldson, R.R.

    1986-10-14

    Wear data are presented for diamond tools cutting electroless nickel (eNi) for cut lengths up to 70,000 ft (13 miles). Two tools having different infrared absorption characteristics were used to cut an eNi preparation that had yielded minimum values for surface roughness and tool wear rate in a previous study. The data include Talystep measurement of the rms amplitude of the feed-marks versus cumulative cutting distance, representative examples of shape changes for the feed-mark profiles, SEM and optical micrographs of the tool rake and flank face wear zones, and measurements of the cutting edge profile and edge recession distance by a tool-nose replication technique. Feed-mark roughness values were found to increase from 5 to 90 A rms over the duration of the test, with an associated edge recession of about 1000 A and the development of a periodic tool edge grooving indicative of burnishing of the part surface. The ir absorption data successfully predicted the order of the two tools in terms of wear rate and fracture toughness.

  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. The evaluation of chemical wear on single crystal diamond tools while diamond turning a binary Cu-Ni alloy system

    NASA Astrophysics Data System (ADS)

    Browy, Eric Calmer

    The current work describes the evaluation of chemical wear on diamond tools while diamond turning copper nickel alloys of varying composition. The primary goal of my project is to quantify the chemical wear of single crystal diamond tools while diamond turning Cu-Ni alloys of different compositions. Pure copper is commonly understood to give negligible tool wear, while pure nickel is reported to give rapid wear. The Cu-Ni equilibrium phase diagram shows a single phase at all compositions. The development and testing of a method to evaluate and quantify diamond tool wear is also described within the current work. The method chosen for development is the metrology of the progressive edge recession of the diamond. A procedure of progressive plunge cuts into an ultra-bright acid copper before and after diamond turning of the workpiece takes a snapshot of the edge of the diamond tool as the cutting distance increases. An algorithm executed in MatLabRTM displays the residual tool wear after removal of the initial diamond tool geometry. A theoretical model has been developed to predict the chemical diamond tool wear and the results will be shown within the body of work.

  5. Wear inspection of a single-crystal diamond tool used in electroless nickel turning

    NASA Astrophysics Data System (ADS)

    Chon, Kwon Su; Takahashi, Hideaki; Namba, Yoshiharu

    2014-03-01

    Single-point diamond turning is a useful optical fabrication method for simultaneously obtaining a smooth surface and generating an accurate shape. Generally, a single-crystal diamond tool has been used in the single-point diamond turning method and a degree of the wear on the diamond tool is unavoidable. Tool wear causes the degradation of the surface quality, surface roughness, and shape accuracy of the workpiece. Inspection of tool wear is important in improving the surface quality. A single-crystal diamond tool used in electroless nickel turning was inspected by a laser scanning microscope and a scanning probe microscope. Regular grooves were observed on the flank face of the diamond tool, and the pitch interval was the same as the feed rate. The worn distance was obtained by measuring the clearance angle and the groove length on the flank face of the worn diamond tool. The worn distance of the diamond tool was 1.7 μm after machining electroless nickel for a 3.18 km cutting distance. The worn distance could also be obtained using the worn width on the flank face and the nose radius and was 2.05 μm, which was very close to 1.7 μm. Two methods based on the wear measurement of the flank face will be new methods to measure the worn distance of the single-crystal diamond tool.

  6. Tool wear of a single-crystal diamond tool in nano-groove machining of a quartz glass plate

    NASA Astrophysics Data System (ADS)

    Yoshino, Masahiko; Nakajima, Satoshi; Terano, Motoki

    2015-12-01

    Tool wear characteristics of a diamond tool in ductile mode machining are presented in this paper. Nano-groove machining of a quartz glass plate was conducted to examine the tool wear rate of a single-crystal diamond tool. Effects of lubrication on the tool wear rate were also evaluated. A numerical simulation technique was developed to evaluate the tool temperature and normal stress acting on the wear surface. From the simulation results it was found that the tool temperature does not increase during the machining experiment. It is also demonstrated that tool wear is attributed to the abrasive wear mechanism, but the effect of the adhesion wear mechanism is minor in nano-groove machining. It is found that the tool wear rate is reduced by using water or kerosene as a lubricant.

  7. Cutting Properties and Wearing Process of Diamond Film Coated Tools in the Dry-Cutting

    NASA Astrophysics Data System (ADS)

    Zhong, Qimao

    Dry cutting can eliminate a series of negative effects of coolant. Based on tribology principle of coated tool, diamond film coated tool is used to cut the same workpiece under the conditions of dry-cutting and coolant. The tool's cutting properties and wear mechanism are studied by tests. Results imply that this coated tool will be applied more widely day by day in the dry-cutting.

  8. Diamond tool wear detection method using cutting force and its power spectrum analysis in ultra-precision fly cutting

    NASA Astrophysics Data System (ADS)

    Zhang, G. Q.; To, S.

    2014-08-01

    Cutting force and its power spectrum analysis was thought to be an effective method monitoring tool wear in many cutting processes and a significant body of research has been conducted on this research area. However, relative little similar research was found in ultra-precision fly cutting. In this paper, a group of experiments were carried out to investigate the cutting forces and its power spectrum characteristics under different tool wear stages. Result reveals that the cutting force increases with the progress of tool wear. The cutting force signals under different tool wear stages were analyzed using power spectrum analysis. The analysis indicates that a characteristic frequency does exist in the power spectrum of the cutting force, whose power spectral density increases with the increasing of tool wear level, this characteristic frequency could be adopted to monitor diamond tool wear in ultra-precision fly cutting.

  9. 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.

  10. Multilayer diamond coated WC tools

    SciTech Connect

    Fan, W.D.; Jagannaham, K.; Narayan, J.

    1995-12-31

    To increase adhesion of diamond coatings, a multilayer structure was developed. The multilayer diamond coating consisted of a first discontinuous diamond layer, an interposing layer, and a top continuous diamond layer. The diamond layer was grown on WC substrates by hot filament chemical vapor deposition and the interposing layer was grown by pulsed laser deposition. Machining tests were used to characterize adhesion properties of the multilayer diamond coatings on WC(Co) substrates. Results indicate that diamond coatings exhibit good adhesion on the WC tool substrates. The wear resistance of the WC tool is improved significantly by the diamond coatings.

  11. 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.

  12. 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.

  13. Diamond Sheet: A new diamond tool material

    NASA Technical Reports Server (NTRS)

    Mackey, C. R.

    1982-01-01

    Diamond sheet is termed a diamond tool material because it is not a cutting tool, but rather a new material from which a variety of different tools may be fabricated. In appearance and properties, it resembles a sheet of copper alloy with diamond abrasive dispersed throughout it. It is capable of being cut, formed, and joined by conventional methods, and subsequently used for cutting as a metal bonded diamond tool. Diamond sheet is normally made with industrial diamond as the abrasive material. The metal matrix in diamond sheet is a medium hard copper alloy which has performed well in most applications. This alloy has the capability of being made harder or softer if specific cutting conditions require it. Other alloys have also been used including a precipitation hardened aluminum alloy with very free cutting characteristics. The material is suitable for use in a variety of cutting, surfacing, and ring type tools, as well as in such mundane items as files and sandpaper. It can also be used as a bearing surface (diamond to diamond) and in wear resistant surfaces.

  14. Anisotropic mechanical amorphization drives wear in diamond

    NASA Astrophysics Data System (ADS)

    Pastewka, Lars; Moser, Stefan; Gumbsch, Peter; Moseler, Michael

    2011-01-01

    Diamond is the hardest material on Earth. Nevertheless, polishing diamond is possible with a process that has remained unaltered for centuries and is still used for jewellery and coatings: the diamond is pressed against a rotating disc with embedded diamond grit. When polishing polycrystalline diamond, surface topographies become non-uniform because wear rates depend on crystal orientations. This anisotropy is not fully understood and impedes diamond’s widespread use in applications that require planar polycrystalline films, ranging from cutting tools to confinement fusion. Here, we use molecular dynamics to show that polished diamond undergoes an sp3-sp2 order-disorder transition resulting in an amorphous adlayer with a growth rate that strongly depends on surface orientation and sliding direction, in excellent correlation with experimental wear rates. This anisotropy originates in mechanically steered dissociation of individual crystal bonds. Similarly to other planarization processes, the diamond surface is chemically activated by mechanical means. Final removal of the amorphous interlayer proceeds either mechanically or through etching by ambient oxygen.

  15. Microstructural characterization of diamond-turned aluminum substrates of memory disks: effects of inclusions on the surface finish and tool wear

    SciTech Connect

    Syn, C.K.

    1986-07-31

    Diamond-turned substrates of computer memory disks of Al-Mg alloys of 5086 and 5186 grades and a worn diamond tool usd in machining 5086 alloy were examined by means of optical and scanning electron microscopy. Detailed analysis of the examination results showed that the undesirable ''orange peel'' finish and accelerated tool wear that occurred in machining 5086 grade alloy disks could be traced to high inclusion content in the material. The iron-containing inclusion particles were shown to be detrimental to the tool life since they could chemically react with the tool material and induce machine tool chatter. The tool wear induced by the inclusion particles then contributed to the ''orange peel'' finish by creating an unevenly cut, rough surface on the disks.

  16. 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.

  17. 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.

  18. An empirical survey on the influence of machining parameters on tool wear in diamond turning of large single crystal silicon optics

    SciTech Connect

    Blaedel, K L; Carr, J W; Davis, P J; Goodman, W; Haack, J K; Krulewich, D; McClellan, M; Syn, C K; Zimmermann, M.

    1999-07-01

    The research described in this paper is a continuation of the collaborative efforts by Lawrence Livermore National Laboratory (LLNL), Schafer Corporation and TRW to develop a process for single point diamond turning (SPDT) of large single crystal silicon (SCSi) optical substrates on the Large Optic Diamond Turning Machine (LODTM). The principal challenge to obtaining long track lengths in SCSi has been to identify a set of machining parameters which yield a process that provides both low and predictable tool wear. Identifying such a process for SCSi has proven to be a formidable task because multiple crystallographic orientations with a range of hardness values are encountered when machining conical and annular optical substrates. The LODTM cutting program can compensate for tool wear if it is predictable. However, if the tool wear is not predictable then the figured area of the optical substrate may have unacceptably high error that can not be removed by post-polishing. The emphasis of this survey was limited to elucidating the influence of cutting parameters on the tool wear. We present two preliminary models that can be used to predict tool wear over the parameter space investigated. During the past two and one-half years a series of three evolutionary investigations were performed. The first investigation, the Parameter Assessment Study (PAS), was designed to survey fundamental machining parameters and assess their influence on tool wear [1]. The results of the PAS were used as a point-of-departure for designing the second investigation, the Parameter Selection Study (PSS). The goal of the PSS was to explore the trends identified in the PAS in more detail, to determine if the experimental results obtained in the PAS could be repeated on a different diamond turning machine (DTM), and to select a more optimal set of machining parameters that could be used in subsequent investigations such as the Fluid Down-Select Study (FDS). The goal of the FDS was to compare

  19. Tool Wear in Friction Drilling

    SciTech Connect

    Miller, Scott F; Blau, Peter Julian; Shih, Albert J.

    2007-01-01

    This study investigated the wear of carbide tools used in friction drilling, a nontraditional hole-making process. In friction drilling, a rotating conical tool uses the heat generated by friction to soften and penetrate a thin workpiece and create a bushing without generating chips. The wear of a hard tungsten carbide tool used for friction drilling a low carbon steel workpiece has been investigated. Tool wear characteristics were studied by measuring its weight change, detecting changes in its shape with a coordinate measuring machine, and making observations of wear damage using scanning electron microscopy. Energy dispersive spectroscopy was applied to analyze the change in chemical composition of the tool surface due to drilling. In addition, the thrust force and torque during drilling and the hole size were measured periodically to monitor the effects of tool wear. Results indicate that the carbide tool is durable, showing minimal tool wear after drilling 11000 holes, but observations also indicate progressively severe abrasive grooving on the tool tip.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Diamond-coated cutting tools for biomedical applications

    NASA Astrophysics Data System (ADS)

    Jackson, M. J.; Hyde, L. J.; Ahmed, W.; Sein, H.; Flaxman, R. P.

    2004-08-01

    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 as a method to improve cutting performance and tool life. WC-Co burs containing 6% Co and 94% WC substrate, with an average grain size of 1 3 µm, were used in this study. To improve the adhesion between diamond and WC substrates, it is necessary to etch away the surface Co and prepare the surface for subsequent diamond growth. Hot filament chemical vapor deposition (HFCVD), with a modified vertical filament arrangement, has been used for the deposition of diamond films. Diamond film quality and purity has been characterized using scanning electron microscopy (SEM) 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, borosilicate glass, and acrylic teeth. Flank wear has been used to assess the wear rates of the burs when machining biomedical materials such as those just described.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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)

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. A Comparative Evaluation of the Wear Resistance of Various Tool Materials in Friction Stir Welding of Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Prater, T.; Strauss, Alvin; Cook, George; Gibson, Brian; Cox, Chase

    2013-06-01

    Friction stir welding (FSW) is the preferred joining method for metal-matrix composites (MMCs). As a solid-state process, it precludes formation of the intermetallic precipitates responsible for degradation of mechanical properties in fusion welds of MMCs. The major barrier to FSW of MMCs is the rapid and severe wear of the welding pin tool, a consequence of prolonged contact between the tool and the harder reinforcements which give the material its enhanced strength. This study evaluates the effectiveness of harder tool materials to combat wear in the FSW of MMCs. The tool materials considered are O1 steel, cemented carbide (WC-Co) of the micrograin and submicrograin varieties, and WC-Co coated with diamond. The challenges which accompany the application of harder tool materials and diamond coatings in FSW are also discussed. This study represents the first use of diamond-coated tools in FSW and the first comparative evaluation of tool materials for this application.

  16. 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.

  17. Cutting Tool Wear After Pulsed Laser Processing in Air

    NASA Astrophysics Data System (ADS)

    Yares'ko, S. I.

    2014-01-01

    We have ascertained the influence of the oxide film formed on the surface of the laser-processed zone of tool steels by irradiation in air on the wear of the cutting tool. It has been shown that laser pulsed processing makes it possible to influence actively the process of its wear. The presence of the oxide film increases the wear stability of the tool in a wide range of cutting speeds, widens the range of cutting regimes in which its least wear is achieved, and minimizes the wear rate. Cutting regimes, in which the highest efficiency of the irradiated tool is achieved, have been established.

  18. Chemical vapour deposition diamond coating on tungsten carbide dental cutting tools

    NASA Astrophysics Data System (ADS)

    Sein, H.; Ahmed, W.; Rego, C. A.; Jones, A. N.; Amar, M.; Jackson, M.; Polini, R.

    2003-10-01

    Diamond coatings on Co cemented tungsten carbide (WC-Co) hard metal tools are widely used for cutting non-ferrous metals. It is difficult to deposit diamond onto cutting tools, which generally have a complex geometry, using a single step growth process. This paper focuses on the deposition of polycrystalline diamond films onto dental tools, which possess 3D complex or cylindrical shape, employing a novel single step chemical vapour deposition (CVD) growth process. The diamond deposition is carried out in a hot filament chemical vapour deposition (HFCVD) reactor with a modified filament arrangement. The filament is mounted vertically with the drill held concentrically in between the filament coils, as opposed to the commonly used horizontal arrangement. This is a simple and inexpensive filament arrangement. In addition, the problems associated with adhesion of diamond films on WC-Co substrates are amplified in dental tools due to the very sharp edges and unpredictable cutting forces. The presence of Co, used as a binder in hard metals, generally causes poor adhesion. The amount of metallic Co on the surface can be reduced using a two step pre-treatment employing Murakami etching followed by an acid treatment. Diamond films are examined in terms of their growth rate, morphology, adhesion and cutting efficiency. We found that in the diamond coated dental tool the wear rate was reduced by a factor of three as compared to the uncoated tool.

  19. Conventional sintering of diamond cutting tool used in natural stone cutting

    NASA Astrophysics Data System (ADS)

    Selvi, Ekin; Topaloglu, Ferit; Tazegul, Onur; Kayali, E. Sabri

    2013-12-01

    Diamond Tools, used in natural stone cutting, is produced commonly by powder metallurgy with Spark Plasma Sintering (SPS) and/or Conventional Sintering (CS). Co is generally used as metal matrices because of their bonding strength and optimum wear rate. However, because of cobalt's high prices, other alloying elements are also used to decrease the cost of diamond tools. Aim of this study is to compare mechanical, physical, microstructural properties of diamond cutting tools made of Co-Ni-Cu-Sn matrix, produced by Spark Plasma Sintering and Conventional Sintering. Spark Plasma Sintering performed at 850 °C and Conventional Sintering performed at various temperatures (between 950 and 1150 °C) and times (1 to 4 hours). Then various properties (density, hardness, compression strength) of Conventional Sintered and Spark Plasma Sintered tools were investigated and compared. The experimental results showed that SPS tools have much better properties than CS tools.

  20. Study of wear of diamond-coated probe tips when scanning on different materials

    NASA Astrophysics Data System (ADS)

    Küng, A.; Nicolet, A.; Meli, F.

    2015-08-01

    The accuracy of today’s coordinate measuring machines (CMM) has reached a level at which the exact knowledge of each component is required. The role of the probe tip is particularly crucial because it is in contact with the sample surface. Understanding how the probe tip wears off will help to narrow the measurement errors. Today, diamond-coated probes of excellent quality are becoming commercially available. In the present work, the wear of those probes was studied when scanning on different sample materials and under different measuring conditions. The wear rate was quantified in terms of the rate of the removed diamond volume per meter scan length. It cannot be simply derived from material properties or scanning conditions. A simple calculation also shows that only a very small fraction of the friction energy is devoted to the removal of atoms from the diamond crystal. The wear rate of diamond-coated probes was found to be orders of magnitude smaller compared with the wear of traditional sapphire probes.

  1. 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.

  2. 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.

  3. A comparative study on wear behavior of TiN and diamond coated WC-Co substrates against hypereutectic Al-Si alloys

    NASA Astrophysics Data System (ADS)

    Chakravarthy, G. V.; Chandran, Maneesh; Bhattacharya, S. S.; Rao, M. S. Ramachandra; Kamaraj, M.

    2012-11-01

    The demand for better tools for machining hypereutectic aluminum-silicon (Al-Si) alloys are increasing day by day since the extensive use of these alloys in internal combustion engines. In addition to the lifetime of the machining tool, surface finish of the machined piece is also equally important, as it directly affects the performance of the engine. In this paper, we compared the wear behavior of bare tungsten carbide (WC-Co), titanium nitride (TiN) coated WC-Co and diamond coated WC-Co substrates against Al-Si alloys using pin-on-disc method. Both TiN and diamond coatings were done using chemical vapor deposition technique. Diamond coated WC-Co substrates show one order less wear loss compared to the bare WC-Co substrates. Instead of weight loss, a weight gain was observed for the TiN coated WC-Co substrates. Average coefficient of friction was lowest for the diamond coated WC-Co substrates due to the different wear behavior of diamond coated tribological system, which is explained in detail.

  4. 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.

  5. Investigation of diamond-impregnated drill bit wear while drilling under Earth and Mars conditions

    NASA Astrophysics Data System (ADS)

    Zacny, K. A.; Cooper, G. A.

    2004-07-01

    Experiments conducted on a dry and a water-saturated rock under Martian and Earth atmospheric pressures revealed two different wear behaviors in diamond-impregnated drill bits. When the rock was saturated, drilling under Martian pressure caused the water in contact with the rotating bit to vaporize. Since the volumetric expansion of the liquid water or ice as it turned into a vapor was 170,000, the continuous flow of water vapor cleared the cuttings out of the hole. Thus the bit matrix was always exposed to abrasive wear by the rock cuttings and was continually wearing down and exposing new diamonds to the rock. When the rock was dry, an accumulation of rock cuttings protected the matrix from abrasive wear. Since fresh diamonds were not exposed in a timely manner, the rate of penetration dropped. Both rock conditions, namely, dry or water saturated, may exist on Mars. This adds to the complexity of the drill bit design as, ideally, a bit should penetrate the rock irrespective of whether it is dry or water saturated. The ``fail-safe'' bit would have a very soft matrix to always produce some rock penetration at the expense of potential excessive bit wear and shallower than anticipated hole depth.

  6. 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.

  7. 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.

  8. Friction and wear properties of smooth diamond films grown in fullerene-argon plasmas

    SciTech Connect

    Erdemir, A.; Fenske, G.R.; Bindal, C.; Zuiker, C.; Krauss, A.R.; Gruen, D.M.

    1995-08-01

    In this study, we describe the growth mechanism and the ultralow friction and wear properties of smooth (20-50 nm rms) diamond films grown in a microwave plasma consisting of Ar and fullerene (the carbon source). The sliding friction coefficients of these films against Si{sub 3}N{sub 4} balls are 0.04 and 0.1 in dry N{sub 2} and air, which are comparable to that of natural diamond sliding against the same pin material, but is lower by factors of 5 to 10 than that afforded by rough diamond films grown in conventional H{sub 2}-CH{sub 4} plasmas. Furthermore, the smooth diamond films produced in this work afforded wear rates to Si{sub 3}N{sub 4} balls that were two to three orders of magnitude lower than those of H{sub 2}-CH{sub 4} grown films. Mechanistically, the ultralow friction and wear properties of the fullerene-derived diamond films correlate well with their initially smooth surface finish and their ability to polish even further during sliding. The wear tracks reach an ultrasmooth (3-6 nm rms) surface finish that results in very little abrasion and ploughing. The nanocrystalline microstructure and exceptionally pure sp{sup 3} bonding in these smooth diamond films were verified by numerous surface and structure analytical methods, including x-ray diffraction, high-resolution AF-S, EELS, NEXAFS, SEM, and TEM. An AFM instrument was used to characterize the topography of the films and rubbing surfaces.

  9. 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.

  10. 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.

  11. Thermal EMF method for monitoring drilling tool wear

    NASA Astrophysics Data System (ADS)

    Pan, Haili; An, Bangjian; Chen, Yu-bao; Orady, Elsayed

    1993-09-01

    This paper describes a techniQue for on-line monitoring of drilling tool wear based on the thermal EMF (electromotive force) signal. The EMF signal was obtained from a natural thermocouple consisting of the tool (H. S. S.) and workpiece (AISI 1045) metals. The natural thermocouple is thus used as a kind of functional sensor which is sensitive to the cutting zone. The signal was collected and analyzed for three experiments at different cutting conditions. Analysis was carried out in time, frequency and amplitude domains. Several indices for the EMF signal were computed and their relationships with the tool wear were constructed. The results showed that the thermal EMF signal can be used to identify the occurrence of abnormal tool wear on major cutting edges and can indicate the end of tool life. Tool breakage can also be predicted. Consequently, a methodology for monitoring drilling tool wear can be established.

  12. 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.

  13. 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. PMID:26024650

  14. 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.

  15. 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.

  16. 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.

  17. Investigation of focused ion beam induced damage in single crystal diamond tools

    NASA Astrophysics Data System (ADS)

    Tong, Zhen; Luo, Xichun

    2015-08-01

    In this work, transmission electron microscope (TEM) measurements and molecular dynamics (MD) simulations were carried out to characterise the focused ion beam (FIB) induced damage layer in a single crystal diamond tool under different FIB processing voltages. The results obtained from the experiments and the simulations are in good agreement. The results indicate that during FIB processing cutting tools made of natural single crystal diamond, the energetic Ga+ collision will create an impulse-dependent damage layer at the irradiated surface. For the tested beam voltages in a typical FIB system (from 8 kV to 30 kV), the thicknesses of the damaged layers formed on a diamond tool surface increased from 11.5 nm to 27.6 nm. The dynamic damage process of FIB irradiation and ion-solid interactions physics leading to processing defects in FIB milling were emulated by MD simulations. The research findings from this study provide the in-depth understanding of the wear of nanoscale multi-tip diamond tools considering the FIB irradiation induced doping and defects during the tool fabrication process.

  18. 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.

  19. Compatibility of the totally replaced hip. Reduction of wear by amorphous diamond coating.

    PubMed

    Santavirta, Seppo

    2003-12-01

    Particulate wear debris in totally replaced hips causes adverse local host reactions. The extreme form of such a reaction, aggressive granulomatosis, was found to be a distinct condition and different from simple aseptic loosening. Reactive and adaptive tissues around the totally replaced hip were made of proliferation of local fibroblast like cells and activated macrophages. Methylmethacrylate and high-molecular-weight polyethylene were shown to be essentially immunologically inert implant materials, but in small particulate form functioned as cellular irritants initiating local biological reactions leading to loosening of the implants. Chromium-cobalt-molybdenum is the most popular metallic implant material; it is hard and tough, and the bearings of this metal are partially self-polishing. In total hip implants, prerequisites for longevity of the replaced hip are good biocompatibility of the materials and sufficient tribological properties of the bearings. The third key issue is that the bearing must minimize frictional shear at the prosthetic bone-implant interface to be compatible with long-term survival. Some of the approaches to meet these demands are alumina-on-alumina and metal-on-metal designs, as well as the use of highly crosslinked polyethylene for the acetabular component. In order to avoid the wear-based deleterious properties of the conventional total hip prosthesis materials or coatings, the present work included biological and tribological testing of amorphous diamond. Previous experiments had demonstrated that a high adhesion of tetrahedral amorphous carbon coatings to a substrate can be achieved by using mixing layers or interlayers. Amorphous diamond was found to be biologically inert, and simulator testing indicated excellent wear properties for conventional total hip prostheses, in which either the ball or both bearing surfaces were coated with hydrogen-free tetrahedral amorphous diamond films. Simulator testing with such total hip prostheses

  20. Ultralow nanoscale wear through atom-by-atom attrition in silicon-containing diamond-like carbon.

    PubMed

    Bhaskaran, Harish; Gotsmann, Bernd; Sebastian, Abu; Drechsler, Ute; Lantz, Mark A; Despont, Michel; Jaroenapibal, Papot; Carpick, Robert W; Chen, Yun; Sridharan, Kumar

    2010-03-01

    Understanding friction and wear at the nanoscale is important for many applications that involve nanoscale components sliding on a surface, such as nanolithography, nanometrology and nanomanufacturing. Defects, cracks and other phenomena that influence material strength and wear at macroscopic scales are less important at the nanoscale, which is why nanowires can, for example, show higher strengths than bulk samples. The contact area between the materials must also be described differently at the nanoscale. Diamond-like carbon is routinely used as a surface coating in applications that require low friction and wear because it is resistant to wear at the macroscale, but there has been considerable debate about the wear mechanisms of diamond-like carbon at the nanoscale because it is difficult to fabricate diamond-like carbon structures with nanoscale fidelity. Here, we demonstrate the batch fabrication of ultrasharp diamond-like carbon tips that contain significant amounts of silicon on silicon microcantilevers for use in atomic force microscopy. This material is known to possess low friction in humid conditions, and we find that, at the nanoscale, it is three orders of magnitude more wear-resistant than silicon under ambient conditions. A wear rate of one atom per micrometre of sliding on SiO(2) is demonstrated. We find that the classical wear law of Archard does not hold at the nanoscale; instead, atom-by-atom attrition dominates the wear mechanisms at these length scales. We estimate that the effective energy barrier for the removal of a single atom is approximately 1 eV, with an effective activation volume of approximately 1 x 10(-28) m. PMID:20118919

  1. Characteristic of wear behavior of micro deep drawing tools

    NASA Astrophysics Data System (ADS)

    Hu, Z.; Huferath-von Luepke, S.; von Kopylow, C.; Vollertsen, F.

    2011-01-01

    In order to investigate the wear behavior of the tools in micro forming, micro deep drawing with a punch diameter of 1 mm was performed. The stainless steel (German standard 1.4301) with a thickness of 0.025 mm was used as blank material. The forming tools are made of tool steel (German standard 1.2379). The mineral oil HBO 947/11 was used as lubricant. Two different failures resulting from tool wear were observed in this investigation. The experimentally measured punch forces show no relation between the change of the maximum punch force and the wear of micro deep drawing tools. Furthermore, the surface of the micro deep drawing tools was investigated using a confocal microscope. It was found that the surface quality of the used die changes clearly with the number of experiments. Moreover, the EDX analysis shows clearly that elements from the blank material exist on the surface of the die. This indicates an adhesive wear in micro deep drawing.

  2. The wear of composite drilling tools and its influence on the energy consumption in drilling

    SciTech Connect

    Mishnaevsky, L.L. Jr.

    1995-11-01

    Theoretical investigations of wear of drilling tools from matrix composites and its influence on the energy consumption in drilling are presented. A formula for wear rate depending on the structure and properties of the tool material is obtained. Influence of drilling conditions and regimes on the composite tool wear is studied on the basis of mathematical model of wear. Relations between the energy consumption in drilling and tool wear are investigated. It is shown that the more heterogeneous are the physical properties of the tool material components, the less the tool wear, and, thus, the less the energy consumption in drilling.

  3. Wear and Friction Characteristics of AlN/Diamond-Like Carbon Hybrid Coatings on Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Nakamura, Masashi; Kubota, Sadayuki; Suzuki, Hideto; Haraguchi, Tadao

    2015-10-01

    The use of diamond-like carbon (DLC) coatings has the potential to greatly improve the wear resistance and friction of aluminum alloys, but practical application has so far been limited by poor adhesion due to large difference in hardness and elasticity between the two materials. This study investigates the deposition of DLC onto an Al-alloy using an intermediate AlN layer with a graded hardness to create a hybrid coating. By controlling the hardness of the AlN film, it was found that the wear life of the DLC film could be improved 80-fold compared to a DLC film deposited directly onto Al-alloy. Furthermore, it was demonstrated through finite element simulation that creating a hardness gradient in the AlN intermediate layer reduces the distribution of stress in the DLC film, while also increasing the force of adhesion between the DLC and AlN layers. Given that both the DLC and AlN films were deposited using the same unbalanced magnetron sputtering method, this process is considered to represent a simple and effective means of improving the wear resistance of Al-alloy components commonly used within the aerospace and automotive industries.

  4. 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/.

  5. 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.

  6. 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.

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

    SciTech Connect

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

    2007-05-17

    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.

  8. Novel testing facility for investigating wear on PGM sample tools

    NASA Astrophysics Data System (ADS)

    Bernhardt, Frank; Georgiadis, Kyriakos; Dambon, Olaf; Klocke, Fritz

    2013-09-01

    For the fabrication of highly precise glass optics, Precision Glass Molding (PGM) is the state-of-the-art replicative manufacturing process. However, the process efficiency is mainly determined by the service lifetime of the molding tools and, in particular, the performance of the protective coatings. Testing the lifetime in real molding machines is extremely cost and effort intensive. In a new testing facility the protective coating performance can be evaluated by systematically inducing tool wear under realistic process conditions. A high number of pressing cycles can be executed under minimal time and material effort, reducing the cost consumption for such coating validation tests significantly. In this paper, a fast method for evaluating the performance of coatings is provided. The machine concept and evaluation method are presented in comparison to the production conditions. Investigations are targeted on the similarities between tool wear in production and those induced in the testing facility. After inducing wear patterns on test specimens in the new facility, surface alterations are characterized with light microscopy. The results show similar degradation patterns as known from production, on the coated tools. The results presented show that the facility provides unique opportunity for optimizing coatings, but also glass compositions, for use in Precision Glass Molding.

  9. Tool wear studies in fabrication of microchannels in ultrasonic micromachining.

    PubMed

    Cheema, Manjot S; Dvivedi, Akshay; Sharma, Apurbba K

    2015-03-01

    Form accuracy of a machined component is one of the performance indicators of a machining process. Ultrasonic micromachining is one such process in which the form accuracy of the micromachined component significantly depends upon the form stability of tool. Unlike macromachining, a very small amount of tool wear in micromachining could lead to considerable changes in the form accuracy of the machined component. Appropriate selection of tool material is essential to overcome this problem. The present study discusses the effect of tool material, abrasive size and step feed in fabrication of microchannels by ultrasonic machining on borosilicate glass. Development of microchannels using ultrasonic micromachining were rarely reported. It was observed that tungsten carbide tool provided a better form accuracy in comparison to the microchannel machined by stainless steel tool. The tool wear mechanism in both materials is proposed by considering scanning electron micrographs of the tool as evidence. A one factor at a time approach was used to study the effect of various process parameters. PMID:25465965

  10. 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.

  11. 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

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

    PubMed

    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 pro-adhesive 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. Machining conditions and the wear of TiC-coated carbide tools

    SciTech Connect

    Lim, C.Y.H.; Lim, S.C.; Lee, K.S.

    1998-07-01

    This paper examines the wear behavior of TiC-coated cemented carbide tools in turning. Experimental data from dry turning tests, together with similar data from the open literature, are used to construct wear maps depicting the flank and crater wear characteristics of these tools over a wide range of machining conditions. The maps show that both flank and crater wear rates vary according to the cutting speeds and feed rates used. An overall wear-damage map for this class of coated tools is also presented for the first time. The presence of the safety zone and the least-wear regime, within which the overall wear damage to the tools is low, suggests the possibility of selecting the machining conditions to achieve a compromise between the rates of material removal and tool wear.

  14. 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.

  15. Tool wear mechanisms in the machining of Nickel based super-alloys: A review

    NASA Astrophysics Data System (ADS)

    Akhtar, Waseem; Sun, Jianfei; Sun, Pengfei; Chen, Wuyi; Saleem, Zawar

    2014-06-01

    Nickel based super-alloys are widely employed in aircraft engines and gas turbines due to their high temperature strength, corrosion resistance and, excellent thermal fatigue properties. Conversely, these alloys are very difficult to machine and cause rapid wear of the cutting tool, frequent tool changes are thus required resulting in low economy of the machining process. This study provides a detailed review of the tool wear mechanism in the machining of nickel based super-alloys. Typical tool wear mechanisms found by different researchers are analyzed in order to find out the most prevalent wear mechanism affecting the tool life. The review of existing works has revealed interesting findings about the tool wear mechanisms in the machining of these alloys. Adhesion wear is found to be the main phenomenon leading to the cutting tool wear in this study.

  16. 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.

  17. Acoustic emission from single point machining: Part 2, Signal changes with tool wear. Revised

    SciTech Connect

    Heiple, C.R.; Carpenter, S.H.; Armentrout, D.L.; McManigle, A.P.

    1989-12-31

    Changes in acoustic emission signal characteristics with tool wear were monitored during single point machining of 4340 steel and Ti-6Al-4V heat treated to several strength levels, 606l-T6 aluminum, 304 stainless steel, 17-4PH stainless steel, 410 stainless steel, lead, and teflon. No signal characteristic changed in the same way with tool wear for all materials tested. A single change in a particular AE signal characteristic with tool wear valid for all materials probably does not exist. Nevertheless, changes in various signal characteristic with wear for a given material may be sufficient to be used to monitor tool wear.

  18. Acoustic emission from single point machining: Part 2, Signal changes with tool wear

    SciTech Connect

    Heiple, C.R.; Carpenter, S.H.; Armentrout, D.L.; McManigle, A.P.

    1989-01-01

    Changes in acoustic emission signal characteristics with tool wear were monitored during single point machining of 4340 steel and Ti-6Al-4V heat treated to several strength levels, 606l-T6 aluminum, 304 stainless steel, 17-4PH stainless steel, 410 stainless steel, lead, and teflon. No signal characteristic changed in the same way with tool wear for all materials tested. A single change in a particular AE signal characteristic with tool wear valid for all materials probably does not exist. Nevertheless, changes in various signal characteristic with wear for a given material may be sufficient to be used to monitor tool wear.

  19. 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.

  20. 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.

  1. Study of Tool Wear Mechanisms and Mathematical Modeling of Flank Wear During Machining of Ti Alloy (Ti6Al4V)

    NASA Astrophysics Data System (ADS)

    Chetan; Narasimhulu, A.; Ghosh, S.; Rao, P. V.

    2014-12-01

    Machinability of titanium is poor due to its low thermal conductivity and high chemical affinity. Lower thermal conductivity of titanium alloy is undesirable on the part of cutting tool causing extensive tool wear. The main task of this work is to predict the various wear mechanisms involved during machining of Ti alloy (Ti6Al4V) and to formulate an analytical mathematical tool wear model for the same. It has been found from various experiments that adhesive and diffusion wear are the dominating wear during machining of Ti alloy with PVD coated tungsten carbide tool. It is also clear from the experiments that the tool wear increases with the increase in cutting parameters like speed, feed and depth of cut. The wear model was validated by carrying out dry machining of Ti alloy at suitable cutting conditions. It has been found that the wear model is able to predict the flank wear suitably under gentle cutting conditions.

  2. Understanding run-in behavior of diamond-like carbon friction and preventing diamond-like carbon wear in humid air.

    PubMed

    Marino, Matthew J; Hsiao, Erik; Chen, Yongsheng; Eryilmaz, Osman L; Erdemir, Ali; Kim, Seong H

    2011-10-18

    The friction behavior of diamond-like carbon (DLC) is very sensitive to the test environment. For hydrogen-rich DLC tested in dry argon and hydrogen, there was always an induction period, so-called "run-in" period, during which the friction coefficient was high and gradually decreased before DLC showed an ultralow friction coefficient (less than 0.01) behavior. Regardless of friction coefficients and hydrogen contents, small amounts of wear were observed in dry argon, hydrogen, oxygen, and humid argon environments. Surprisingly, there were no wear or rubbing scar on DLC surfaces tested in n-pentanol vapor conditions, although the friction coefficient was relatively high among the five test environments. Ex situ X-ray photoelectron and near-edge X-ray absorption fine-structure spectroscopy analyses failed to reveal any differences in chemical composition attributable to the environment dependence of DLC friction and wear. The failure of getting chemical information of oxygenated surface species from the ex situ analysis was found to be due to facile oxidation of the DLC surface upon exposure to air. The removal or wear of this surface oxide layer is responsible for the run-in behavior of DLC. It was discovered that the alcohol vapor can also prevent the oxidized DLC surface from wear in humid air conditions. PMID:21888344

  3. Diamond Coatings

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Advances in materials technology have demonstrated that it is possible to get the advantages of diamond in a number of applications without the cost penalty, by coating and chemically bonding an inexpensive substrate with a thin film of diamond-like carbon (DLC). Diamond films offer tremendous technical and economic potential in such advances as chemically inert protective coatings; machine tools and parts capable of resisting wear 10 times longer; ball bearings and metal cutting tools; a broad variety of optical instruments and systems; and consumer products. Among the American companies engaged in DLC commercialization is Diamonex, Inc., a diamond coating spinoff of Air Products and Chemicals, Inc. Along with its own proprietary technology for both polycrystalline diamond and DLC coatings, Diamonex is using, under an exclusive license, NASA technology for depositing DLC on a substrate. Diamonex is developing, and offering commercially, under the trade name Diamond Aegis, a line of polycrystalline diamond-coated products that can be custom tailored for optical, electronic and engineering applications. Diamonex's initial focus is on optical products and the first commercial product is expected in late 1990. Other target applications include electronic heat sink substrates, x-ray lithography masks, metal cutting tools and bearings.

  4. 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.

  5. 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

  6. Friction and fretting wear characteristics of different diamond-like carbon coatings against alumina in water-lubricated fretting conditions.

    PubMed

    Watabe, Tsukasa; Amanov, Auezhan; Tsuboi, Ryo; Sasaki, Shinya

    2013-12-01

    Diamond-like carbon (DLC) coatings typically show low friction and high wear resistance. In this study, the friction and fretting wear characteristics of PVD, CVD and CVD-Si DLC coatings were investigated against an alumina (Al2O3) ball under water-lubricated fretting conditions. The objective of this study is to investigate and compare the friction and fretting wear characteristics of those DLC coatings at various fretting frequencies. The test results showed that the PVD DLC coating led to a lower friction coefficient and a higher resistance to fretting wear compared to those of the CVD and CVD-Si DLC coatings. However, the CVD DLC coating showed that the fretting wear resistance decreases with increasing frequency, while no significant difference in fretting wear resistances of the PVD and CVD-Si DLC coatings was observed. Quantitative surface analyses of the specimens were performed using an energy dispersive spectroscopy (EDS), a laser scanning microscope (LSM), a scanning electron microscope (SEM), an atomic force microscope (AFM) and the Raman spectroscopy. PMID:24266210

  7. 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.

  8. Statistical description of the macrostructure of diamond-containing powder tool materials

    NASA Astrophysics Data System (ADS)

    Vinokurov, G. G.; Sharin, P. P.; Popov, O. N.

    2015-12-01

    The macrostructure of diamond-containing tool material has been investigated. The potentials of application of a cluster theory for processing a digital metallographic image of a diamond-containing powder material are substantiated. It is proposed to consider agglomerates of diamond grains to estimate the heterogeneity of a two-phase macrostructure.

  9. Investigation of the shape transferability of nanoscale multi-tip diamond tools in the diamond turning of nanostructures

    NASA Astrophysics Data System (ADS)

    Luo, Xichun; Tong, Zhen; Liang, Yingchun

    2014-12-01

    In this article, the shape transferability of using nanoscale multi-tip diamond tools in the diamond turning for scale-up manufacturing of nanostructures has been demonstrated. Atomistic multi-tip diamond tool models were built with different tool geometries in terms of the difference in the tip cross-sectional shape, tip angle, and the feature of tool tip configuration, to determine their effect on the applied forces and the machined nano-groove geometries. The quality of machined nanostructures was characterized by the thickness of the deformed layers and the dimensional accuracy achieved. Simulation results show that diamond turning using nanoscale multi-tip tools offers tremendous shape transferability in machining nanostructures. Both periodic and non-periodic nano-grooves with different cross-sectional shapes can be successfully fabricated using the multi-tip tools. A hypothesis of minimum designed ratio of tool tip distance to tip base width (L/Wf) of the nanoscale multi-tip diamond tool for the high precision machining of nanostructures was proposed based on the analytical study of the quality of the nanostructures fabricated using different types of the multi-tip tools. Nanometric cutting trials using nanoscale multi-tip diamond tools (different in L/Wf) fabricated by focused ion beam (FIB) were then conducted to verify the hypothesis. The investigations done in this work imply the potential of using the nanoscale multi-tip diamond tool for the deterministic fabrication of period and non-periodic nanostructures, which opens up the feasibility of using the process as a versatile manufacturing technique in nanotechnology.

  10. 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.

  11. Tribological and cutting behavior of silicon nitride tools coated with monolayer- and multilayer-microcrystalline HFCVD diamond films

    NASA Astrophysics Data System (ADS)

    Chen, Naichao; Shen, Bin; Yang, Guodong; Sun, Fanghong

    2013-01-01

    Monolayer-micrometric (MN-MCD), monolayer-submicrometric (MN-SMCD) and multilayer-micrometric (MT-MCD) diamond films are grown on silicon nitride substrates by hot filament chemical vapor deposition (HFCVD) technique. The as-deposited diamond films are characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDS), Raman spectrum and 3D surface topography. Tribological properties are assessed by the sliding tests using a reciprocal motion ball-on-flat (BOF) configuration. The friction coefficients are measured as 0.126 for the MN-MCD films, 0.076 for the MN-SMCD films and 0.071 for the MT-MCD films during dry sliding against silicon nitride counterface. The different carbon content of the films may result in the visible diminution of friction coefficient for the MT-MCD films relative to the MN-MCD films. The results show that the MN-MCD and MT-MCD films present the much higher wear resistance than the MN-SMCD films. Meanwhile, the cutting performances of as-deposited diamond films are evaluated by machining aluminum-silicon alloy material. The experimental results show that the MT-MCD insert presents the best behavior regarding the tool wear.

  12. Estimation of tool wear during CNC milling using neural network-based sensor fusion

    NASA Astrophysics Data System (ADS)

    Ghosh, N.; Ravi, Y. B.; Patra, A.; Mukhopadhyay, S.; Paul, S.; Mohanty, A. R.; Chattopadhyay, A. B.

    2007-01-01

    Cutting tool wear degrades the product quality in manufacturing processes. Monitoring tool wear value online is therefore needed to prevent degradation in machining quality. Unfortunately there is no direct way of measuring the tool wear online. Therefore one has to adopt an indirect method wherein the tool wear is estimated from several sensors measuring related process variables. In this work, a neural network-based sensor fusion model has been developed for tool condition monitoring (TCM). Features extracted from a number of machining zone signals, namely cutting forces, spindle vibration, spindle current, and sound pressure level have been fused to estimate the average flank wear of the main cutting edge. Novel strategies such as, signal level segmentation for temporal registration, feature space filtering, outlier removal, and estimation space filtering have been proposed. The proposed approach has been validated by both laboratory and industrial implementations.

  13. 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.

  14. The Effects of Diamond-Like Carbon Films on Fretting Wear Behavior of Orthodontic Archwire-Bracket Contacts.

    PubMed

    Kang, Ting; Huang, Shi-You; Huang, Jie-Jie; Li, Qi-Hong; Diao, Dong-Feng; Duan, Yin-Zhong

    2015-06-01

    This study aims to assess the effects of diamond-like carbon (DLC) films on fretting wear behavior of orthodontic archwire-bracket contacts. 'Mirror-confinement-type electron cyclotron resonance (MCECR) plasma sputtering' was utilized to deposit carbon films on stainless steel archwires and brackets. Nanostructure of carbon films such as the bonding structure, cross-sectional thickness and surface roughness were studied. The fretting wear behavior of various archwire-bracket contacts were investigated by using a self-developed tester in ambient air and artificial saliva. The results indicated that DLC-coated wires showed significantly low friction coefficient than the uncoated wires independently of the applied environments. Nevertheless, the DLC-coated and uncoated brackets showed no significant differences in the friction coefficient. Microscopic analysis showed that low wear took place for the DLC-coated surfaces. It is proposed that the application of DLC coating on archwires can decrease the orthodontic fretting wear and coefficient of friction. Unfortunately it does not affect the frictional properties for brackets at present. PMID:26369091

  15. The use of analytical surface tools in the fundamental study of wear

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1977-01-01

    This paper reviews the various techniques and surface tools available for the study of the atomic nature of the wear of materials. 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 effect 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Wear Reduction Effects of Ca Sulfonate on Coated Tools in Hobbing

    NASA Astrophysics Data System (ADS)

    Matsuoka, Hironori; Ono, Hajime; Tsuda, Yoshihiro

    This paper presents the influence of Ca sulfonate on tool life (flank wear), crater wear and finished surface roughness in hobbing. Experiments were carried out using two kinds of fully coated fly tools with TiN and (Al, Ti)N films respectively. As the results, when using the TiN fully coated tool, Ca sulfonate prolongs the tool life, and decreases the crater wear compared with the machine oil 23 as a base oil. With the (Al, Ti)N fully coated tool, an interesting result was obtained that the base oil containing no additives gives a longer tool life and a smaller crater wear than those obtained with Ca sulfonates added. It was suggested that the increase in the flank wear and the crater wear is caused by the chemical and/or the corrosive actions of Ca sulfonate, when Ca sulfonate was used for the (Al, Ti)N coated tool. Ca sulfonates improve the finished surface roughness for both coated tools.

  2. 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.

  3. Studies of the frictional heating of polycrystalline diamond compact drag tools during rock cutting

    SciTech Connect

    Ortega, A.; Glowka, D.A.

    1982-06-01

    A numerical-analytical model is developed to analyze temperatures in polycrystalline diamond compact (PDC) drag tools subject to localized frictional heating at a worn flat area and convective cooling at exposed lateral surfaces. Experimental measurements of convective heat transfer coefficients of PDC cutters in a uniform crossflow are presented and 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 found that average temperatures at the wearflat contact zone vary directly with frictional force per unit area and are proportional to the one-half power of the cutting speed at the velocities investigated. Temperatures are found to be much more sensitive to decreases in the dynamic friction by lubrication than to increases in convective cooling rates beyond currently achievable levels with water or drilling fluids. It is shown that use of weighted drilling fluids may actually decrease cooling rates compared to those achieved with pure water. It is doubtful that tool temperatures can be kept below critical levels (750/sup 0/C) if air is employed as the drilling fluid. The degree of tool wear is found to have a major influence on the thermal response of the friction contact zone, so that for equal heating per contact area, a worn tool will run much hotter than a sharp tool. It is concluded that tool temperatures may be kept below critical levels with conventional water or mud cooling as long as the fluid provides good cutter-rock lubrication.

  4. Tool decentration effect in slow tool servo diamond turning off-axis conic aspheric surface

    NASA Astrophysics Data System (ADS)

    Dai, Yi-fan; Guan, Chaoliang; Yin, Zi-qiang; Tie, Gui-peng; Chen, Hao-feng; Wang, Jian-min

    2010-10-01

    Off-axis conic aspheric mirrors are crucial components in some optical systems, such as three-mirror-anastigmatic telescopes (TMA). However, because of the swing limitation of lathe, off-axis aspheric mirrors are not easy to fabricate using a general-purpose diamond turning machine. This research demonstrates slow tool servo diamond turning process which allows fabricating off-axis conic aspheric mirrors on-axis. The figure error caused by tool centering error was studied on. An off-axis parabolic mirror was fabricated and actual machining data are discussed. The result proved that proposed approach is capable of fabricating copper off-axis parabolic mirror of 46mm diameter to a form accuracy of 0.736μm in PV error value.

  5. Creation Of The Residual Stress By Influence Of Wear Of Cutting Tool And Their Analysis

    NASA Astrophysics Data System (ADS)

    Kordík, Marek; Čilliková, Mária; Mrazik, Jozef; Martinček, Juraj; Janota, Miroslav; Nicielnik, Henryk

    2015-12-01

    The aim of this paper is analysis of turned bearing ring made of material 14109 (DIN 100Cr6) without heat treatment. For the analysis a mechanical destructive method was chosen. Analysis focused on existence and character of residual stresses after turning operation of bearing ring by tool with different level of wear. The experiment reveals the relationships between residual stress creation and cutting tool wear.

  6. 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.

  7. 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

  8. Wear testing of friction stir spot welding tools for joining of DP 980 Steel

    SciTech Connect

    Ridges, Chris; Miles, Michael; Hovanski, Yuri; Peterson, Jeremy; Steel, Russell

    2011-06-06

    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. Several tooling materials have been evaluated in prior studies, including silicon nitride and polycrystalline cubic boron nitride (PCBN). Recently a new tool alloy has been developed, where a blend of PCBN and tungsten rhenium (W-Re) was used 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 (designated as Q60), and one with 70% PCBN and 30% W-Re (designated at Q70). The sheet material used for all wear testing was DP 980. Tool profiles were measured periodically during the testing process in order to show the progression of wear as a function of the number of spots produced. Lap shear testing was done each time a tool profile was taken in order to show the relationship between tool wear and joint strength. For the welding parameters chosen for this study the Q70 tool provided the best combination of wear resistance and joint strength.

  9. Approach to in-process tool wear monitoring in drilling: Application of Kalman filter theory

    NASA Astrophysics Data System (ADS)

    He, Ning; Zhang, Youzhen; Pan, Liangxian

    1993-05-01

    The two parameters often used in adaptive control, tool wear and wear rate, are the important factors affecting machinability. In this paper, it is attempted to use the modern cybernetics to solve the in-process tool wear monitoring problem by applying the Kalman filter theory to monitor drill wear quantitatively. Based on the experimental results, a dynamic model, a measuring model and a measurement conversion model suitable for Kalman filter are established. It is proved that the monitoring system possesses complete observability but does not possess complete controllability. A discriminant for selecting the characteristic parameters is put forward. The thrust force Fz is selected as the characteristic parameter in monitoring the tool wear by this discriminant. The in-process Kalman filter drill wear monitoring system composed of force sensor microphotography and microcomputer is well established. The results obtained by the Kalman filter, the common indirect measuring method and the real drill wear measured by the aid of microphotography are compared. The result shows that the Kalman filter has high precision of measurement and the real time requirement can be satisfied.

  10. 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.

  11. Diamond turning of steel in a carbon-saturated atmosphere

    SciTech Connect

    Casstevens, J.M.

    1982-06-02

    The wear of diamond tools when machining steels under carbon dioxide and methane gases is investigated. It is shown that diamond tool wear on steels appears to be significantly reduced due to the effects of the methane gas atmosphere. Applicable literature is reviewed and an explanation for the effectiveness of a gas rich in carbon is given. A description of the experimental apparatus and procedure is given along with results of experiments with two types of steel.

  12. Tool wear in cryogenic turning of Ti-6Al-4V alloy

    NASA Astrophysics Data System (ADS)

    Venugopal, K. A.; Paul, S.; Chattopadhyay, A. B.

    2007-01-01

    Though titanium alloys are being increasingly sought in a wide variety of engineering and biomedical applications, their manufacturability, especially machining and grinding imposes lot of constraints. Rapid tool wear encountered in machining of titanium alloys is a challenge that needs to be overcome. Cryogenic machining with liquid nitrogen as coolant is being investigated by researchers to reduce the cutting zone temperatures and enhance the tool life. The effects of cryogenic cooling have been studied on growth and nature tool wear in the present investigation while turning Ti-6Al-4V alloy bars with microcrystalline uncoated carbide inserts under dry, wet and cryogenic cooling environments in the cutting velocity range of 70-100 m/min. Cryogenic cooling by liquid nitrogen jets enabled substantial improvement in tool life through reduction in adhesion-dissolution-diffusion tool wear through control of machining temperature desirably at the cutting zone.

  13. A Phenomenological Model for Tool Wear in Friction Stir Welding of Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Prater, Tracie J.; Strauss, Alvin M.; Cook, George E.; Gibson, Brian T.; Cox, Chase D.

    2013-08-01

    Friction stir welding (FSW) of metal matrix composites (MMCs) is advantageous because the solid-state nature of the process precludes formation of deleterious intermetallic phases which accompany melting. FSW of MMCs is complicated by rapid and severe wear of the welding tool, a consequence of contact between the tool and the much harder abrasive reinforcement which gives the workpiece material its enhanced strength. The current article demonstrates that Nunes's rotating plug model of material flow in FSW, which has been successfully applied in many other contexts, can also help us understand wear in FSW of MMCs. An equation for predicting the amount of wear in this application is developed and compared with experimental data. This phenomenological model explains the relationship between wear and FSW process parameters documented in previous studies.

  14. Acoustic emission from single point machining: Source mechanisms and signal changes with tool wear

    SciTech Connect

    Heiple, C.R.; Carpenter, S.H.; Armentrout, D.L.; McManigle, A.P.

    1994-05-01

    Acoustic emission (AE) was monitored during single point, continuous machining of 4340 steel and Ti-6Al-4V as a function of heat treatment. Heat treatments that increase the strength of 4340 steel substantially increase the amount of AE produced during deformation, while heat treatments that increase the strength of Ti-6Al-4V dramatically decrease the amount of AE produced during deformation. There was little change in root-mean-square (rms) AE level during machining for either alloy as a function of prior heat treatment, demonstrating that chip deformation is not a major source of AE in single point machining. Additional data from a variety of materials suggest that sliding friction between the nose and/or flank of the tool and the newly machined surface is the primary source of AE. Changes in AE signal characteristics with tool wear were also monitored during single point machining. No signal characteristic changed in the same way with tool wear for all materials tested. A single change in a particular AE signal characteristic with tool wear valid for all materials probably does not exist. Nevertheless, changes in various signal characteristics with wear for a given material may be sufficient to be used to monitor tool wear.

  15. Frictional Characterization of Chemical-Mechanical Polishing Pad Surface and Diamond Conditioner Wear

    NASA Astrophysics Data System (ADS)

    Yamada, Yohei; Kawakubo, Masanori; Hirai, Osamu; Konishi, Nobuhiro; Kurokawa, Syuhei; Doi, Toshiro

    2008-08-01

    We evaluated a contact metrology instrument used in chemical-mechanical polishing (CMP) systems for high-volume manufacture and examined in situ coefficient of friction (COF) monitoring to identify the tribology of CMP, and subsequently to determine the useful lifespan of consumables. The results showed that the direct measurement of the wear of the pad allowed for an accurate determination of both pad thickness and the ideal time to replace the pad and conditioner disk based on pad wear rate. We also presented a clear correlation between the working grid area of the conditioner disk and the tribological behavior of the pad break-in procedure, leading to the result showing that the variation in tungsten film removal rate decreased as the working grid density of the conditioner disk increased. This study has proven the effectiveness of measuring friction force for better CMP control.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Investigation on Tool Wear Rate for Modified and Unmodified Aluminium-Silicon Casting Alloy

    NASA Astrophysics Data System (ADS)

    Haque, M. M.; Khan, A. A.; Ismail, Ahmad F.

    This study demonstrates and explains the effect of strontium modification on machinability of aluminium-silicon eutectic (LM-6 type) alloy. This alloy is known to have many favourable features including weight to strength ratio, high corrosion resistance and excellent castability. However, normal unmodified LM-6 alloy has poor machinability, which reduces its applications range. In this work, various samples of LM-6 alloy were cast using sand and metallic chill mould with and without strontium addition. Machining on each cast product, was carried out using recommended cutting parameters for Al-Si alloys. Strontium modified samples have recorded a reduction in average flank wear, an increase in shear plane angles and a reduction in chip thickness. The main reason for this improvement is the refining effect of strontium, which reduces the size of the hard silicon particles. As a result, their abrasive action on the tool face has reduced a lot. Dramatic reductions in tool wear rate were recorded when the microstructures were refined. On the other hand, when no refinement of microstructure occurs, tool wear rate becomes high. Chip analysis showed that strontium modified sample produced a thinner chip thickness with a larger shear plane angle, requiring less cutting forces. The tool wear depends not only on the phases present in the work material, but also on their sizes and distribution over entire structure. Thus, strontium modification has better effect on machinability of die cast alloy compared to that of the sand cast LM-6 alloy.

  4. Slow tool servo diamond turning of optical freeform surface for astigmatic contact lens

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Chieh; Cheng, Yuan-Chieh; Hsu, Wei-Yao; Chou, Hsiao-Yu; Wang, Pei-Jen; Tsai, Din Ping

    2011-09-01

    Three ultra-precision machining processes namely fast tool servo, slow tool servo and diamond milling, are frequently used to produce optical freeform surface. Slow tool servo machining has the advantages of no extra attachment and fast setting-up, however the three dimensional tool shape compensation and tool-path generation must be conducted carefully for getting high form accuracy and fine surface finish. This research aimed to develop a model of three dimensional tool shape compensation for generating 3D tool path in slow tool servo diamond turning of asymmetrically toric surface for astigmatic contact lens. The form accuracy of freeform surface was measured by ultra-high accuracy 3D profilometer (UA3P) with user define function. After correction, the form error is less than 0.5μm both in X- and Y-direction and the surface roughness is less than 5nm.

  5. Investigations of High Temperature Wear Mechanisms for Tool Steel Under Open-Sliding Contact

    NASA Astrophysics Data System (ADS)

    Mnif, R.; Baccouch, Z.; Elleuch, R.; Richard, C.

    2014-08-01

    During hot working processes, working tools are subjected to severe conditions. Wear is one of the major life limiting factors of the hot working tools. The identification and understanding of the wear mechanism are extremely important for solving problems related to the hot working process. The ultimate aim of this paper is to assess some wear mechanisms of the tool steel used in hot drawing. The tribological tests were performed on high temperature pin-on-disc tribometer with an open-sliding contact for a simulation of hot-drawing process with a refreshed contact surface. The pin material was X40 CrMoV5 steel and the disc material was Fe 360B steel. Experiments were carried out for different disc temperatures ranging from room temperature to 800°C, a constant sliding speed of 50 rev/min and a constant normal load of 70 N. The evolution surface damage and oxides tribolayers have been investigated by SEM and EDS. The results have shown that an increase in test temperature facilitates the generation of oxide and assists in the compaction of the debris, thus producing a wear protective layer, and therefore, a reduction in friction coefficient.

  6. 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.

  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. 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.

  9. 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

  10. 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.

  11. 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.

  12. Dissolution wear: Decomposition of tool material, and concentration profile into chip

    NASA Astrophysics Data System (ADS)

    Wong, Tim Kong-Ping

    The predictive capability of Kramer's theory of dissolution wear has raised questions as to whether dissolution or diffusion is the dominant mechanism underlying tool wear. The diffusion mechanism finds support in experimentation and modeling of mass transfer (e.g., the Molinari-Nouari model of the experimental findings of Subramanian et al.), and fits more naturally in the setting of the irreversibilities of turning processes. Kramer's dissolution mechanism, by contrast, is based on equilibrium thermodynamics. Our present aim is to re-phrase the dissolution hypothesis of tool wear as a boundary condition for species transfer within the chip's bulk via diffusion. In this setting, dissolution is defined as the combined events of tool decomposition at the interface and the subsequent mass transfer of decomposed elements into the chip region. A set of equations is constructed wherein the tool is treated as a mechanically rigid, but chemically active, thermal conductor; the chip is treated as a rigid-perfectly plastic, thermally conducting material; and the behavior of the frictional-contact interface between tool and chip is described by a weak coupling of thermal and mass transfer. Chemical equilibrium is invoked for the distribution of tool species at the tool-chip interface. The Frank-Turnbull mechanism of molecular reaction (between interstitial impurities and vacancies to form substitutional impurities) is used as a hypothesis to explain the concentration profile of tool constituents into the chip as found by Subramanian et al. in 1993. The present interpretation of the Frank-Turnbull mechanism is illustrated by finite-element simulations. Physical parameters have either been estimated or curve-fitted to observed data, and the level of inexactness inherent in the curve-fit process limits the present work to a demonstration of only the sufficiency of the model. The assumptions made, their implications, parameters varied, and quantities calculated are summarized in

  13. 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.

  14. 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.

  15. Tool wear detection in milling—An original approach with a non-dedicated sensor

    NASA Astrophysics Data System (ADS)

    Girardin, François; Rémond, Didier; Rigal, Jean-François

    2010-08-01

    The aim of increasing productivity often makes optimising processes a priority and a means of anticipating defects. Metal cutting conditions are monitored to detect tool wear or breaks, so as to protect both machines and workpieces. Such monitoring relies on many different signals though two main approaches can be considered. The first consists in adding numerous sensors to the machine to obtain specific information, such as vibrations and cutting forces. The second consists in using information, often current or shaft power consumption, that can already be obtained from the machine and detected by standard sensors. This work focuses on the second approach that relies on using the sensors already installed, but optimising their capacities to the maximum for use under industrial conditions. The spindle rotary encoder signal is acquired through two systems: the first uses classical time-sampling while the second uses specific angular-sampling methodology. The differences between the two rotational frequency calculation technologies are described and discussed before focusing on the second methodology. Comparisons of cutting forces and variations in spindle rotational frequency reveal considerable similarities. Thus the occurrence of tool wear can be observed by monitoring variations in rotational frequency, and the genesis of tool tooth breaks can be established. Finally, we establish criteria for critical wear detection in both time and frequency domains.

  16. Tool wear monitoring by machine learning techniques and singular spectrum analysis

    NASA Astrophysics Data System (ADS)

    Kilundu, Bovic; Dehombreux, Pierre; Chiementin, Xavier

    2011-01-01

    This paper explores the use of data mining techniques for tool condition monitoring in metal cutting. Pseudo-local singular spectrum analysis (SSA) is performed on vibration signals measured on the toolholder. This is coupled to a band-pass filter to allow definition and extraction of features which are sensitive to tool wear. These features are defined, in some frequency bands, from sums of Fourier coefficients of reconstructed and residual signals obtained by SSA. This study highlights two important aspects: strong relevance of information in high frequency vibration components and benefits of the combination of SSA and band-pass filtering to get rid of useless components (noise).

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Hardening effect on machined surface for precise hard cutting process with consideration of tool wear

    NASA Astrophysics Data System (ADS)

    Yue, Caixu; Liu, Xianli; Ma, Jing; Liu, Zhaojing; Liu, Fei; Yang, Yongheng

    2014-11-01

    During hard cutting process there is severe thermodynamic coupling effect between cutting tool and workpiece, which causes quenching effect on finished surfaces under certain conditions. However, material phase transformation mechanism of heat treatment in cutting process is different from the one in traditional process, which leads to changes of the formation mechanism of damaged layer on machined workpiece surface. This paper researches on the generation mechanism of damaged layer on machined surface in the process of PCBN tool hard cutting hardened steel Cr12MoV. Rules of temperature change on machined surface and subsurface are got by means of finite element simulation. In phase transformation temperature experiments rapid transformation instrument is employed, and the effect of quenching under cutting conditions on generation of damaged layer is revealed. Based on that, the phase transformation points of temperature under cutting conditions are determined. By experiment, the effects of cutting speed and tool wear on white layer thickness in damaged layer are revealed. The temperature distribution law of third deformation zone is got by establishing the numerical prediction model, and thickness of white layer in damaged layer is predicted, taking the tool wear effect into consideration. The experimental results show that the model prediction is accurate, and the establishment of prediction model provides a reference for wise selection of parameters in precise hard cutting process. For the machining process with high demanding on surface integrity, the generation of damaged layer on machined surface can be controlled precisely by using the prediction model.

  3. 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.

  4. Tool wear modelling/life prediction: Final report for the period September 1, 1986--February 29, 1988

    SciTech Connect

    Kramer, B.M.

    1988-12-01

    A calibrated analytical model of cutting tool wear has been developed to allow for the prediction of the wear rates of potential coatings for cutting tool materials. The model has been used to select coating compositions which may provide improved performance, as compared to existing titanium nitride based coatings. The model predicts that the wear resistance of the IVB nitrides will increase in the order TiN, ZrN and HfN. In addition, it predicts that the wear resistance of the binary nitride (Ti,Hf)N will be greater than that of either of the component mononitrides under the cutting conditions which are commonly used in the machining of steel with high speed steel tooling. 7 refs., 6 figs.

  5. Diamond turning of optical crystals

    SciTech Connect

    Saito, T.T.; Syn, C.K.; Fuchs, B.A.; Velsko, S.P.

    1990-03-01

    Diamond turning (DT) has proven to be a cost effective optical fabrication technique for both aspherical and spherical/flat figures when precise geometrical tolerances are important. We are interested in the DT of crystals for several reasons. DT has been very effective to insure requisite accurate geometrical orientation of optical surfaces to crystalline axes for frequency conversion applications. Also, DT can achieve figure up to the edge of the crystal. Another key DT benefit is enhanced laser damage threshold, which we feel in part is due to the freedom of the surface from polishing impurities. Several important issues for diamond turning optical crystals are the tool wear, associated surface finish, and laser damage properties. We have found that careful selection and control of diamond turning parameters can yield production techniques for crystals previously considered incompatible with diamond turning. 8 refs., 2 tabs.

  6. A Morlet wavelet signal analysis with a Daubechies filter for the wear assessment of hip prostheses coated with diamond-like carbon by triboadhesion.

    PubMed

    Rodríguez-Lelis, Jose Maria; Mata, Dagoberto Tolosa; Vargas-Treviño, Marciano; Navarro-Torres, Jose; Piña-Piña, Gilberto; Abundez-Pliego, Arturo

    2010-08-01

    In the present work, based on high frequency wavelet analysis of dynamic signals of mechanical systems, a multiple-resolution wavelet analysis is carried out, to the signal obtained from an accelerometer mounted on the structure of a hip prosthesis wearing test device. The prostheses employed had a femoral head made of aluminum oxide and the acetabular cup of ultra-high-molecular-weight polyethylene. The first two aluminum oxide femoral heads were coated with diamond-like carbon and a third one was tested without coating and used as a reference. The coating was carried out by triboadhesion. Tests results showed that maximum vibration amplitude reached after 32 hr for the coated prostheses was 0.2 g. The noncoated prosthesis amplitude presented was 0.75 g in the same time interval. These values were attributed to wear damage on the surface of the prostheses, indicating that thin film DLC coating caused an increase of stiffness on the surface and therefore an increase in wear resistance approximately of 314%. PMID:20841618

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    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° 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° 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.

  17. 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.

  18. Comparative investigation of smooth polycrystalline diamond films on dental burs by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Sein, Htet; Ahmed, Waqar; Rego, Christopher; Jackson, Mark; Polini, Riccardo

    2006-04-01

    Depositions of hot filament chemical vapor-deposited diamond on cobalt-cemented tungsten carbide (WC-Co) rotary cutting dental burs are presented. Conventional dental tools made of sintered polycrystalline diamond have a number of problems associated with the heterogeneity of the crystallite, decreased cutting efficiency, and short life. A preferential (111) faceted diamond was obtained after 15 h of deposition at a growth rate of 1.1 µm/h. Diamond-coated WC-Co dental burs and conventional sintered burs are mainly used in turning, milling, and drilling operations for machining metal ceramic hard alloys such as CoCr, composite teeth, and aluminum alloy in the dental laboratory. The influence of structure, the mechanical characteristics of both diamond grains and hard alloys on the wear behavior, as well as the regimen of grinding on diamond wear are considered. Erosion wear properties are also investigated under air-sand erosion testing. After machining with excessive cutting performance, calculations can be made on flank and crater wear areas. Diamond-coated WC-Co dental burs offered significantly better erosion and wear resistance compared with uncoated WC-Co tools and sintered burs.

  19. Influence of the tribological phenomenon on the tool wear in dry drilling of aluminum alloy AA2024 T351

    NASA Astrophysics Data System (ADS)

    Nouari, M.; List, G.; Girot, F.

    2003-09-01

    In machining, the formation of chip and tool wear is controlled by the tribological phenomenon at the tool-chip interface. Investigations show that the contact between the tool and the chip tends to change from a sliding contact to a sticking contact. When the cutting speed is increased, the tool rake face temperature can attain large values (sometimes of the order of 1000 °C in the case of machining steels). Without the use of coolants and lubricants, this temperature can be higher. These high temperatures are due to the important deformation work associated with large shear strains in the primary shear zone, and to the friction effects along the tool-chip interface. An experimental analysis of the tool wear for dry machining of aeronautic aluminum alloy AA2024 T351 is proposed. The change in the tribological conditions at the tool-chip interface is discussed.

  20. Monitoring of Burr and Prefailure Phase Caused by Tool Wear in Micro-Drilling Operations Using Thrust Force Signals

    NASA Astrophysics Data System (ADS)

    Kondo, Eiji; Kamo, Ryoga; Murakami, Hiroshi

    The purpose of this study is to investigate the effectiveness of thrust force signals for estimation of the burr occurring at the outlet of a drilled hole and the prefailure phase caused by tool wear in drilling holes through thin stainless steel plate (JIS SUS304). Micro-drilling tests, using feed rate, step feed length, and the micro-drill diameter as experimental parameters, were carried out to measure the thrust force during peck drilling operations. Tool wear of the cutting edge and burr occurring at the outlet of drilled holes were measured at intervals of a constant number of drilled holes to consider their relationships to thrust force. As a result, the thrust force caused by tool wear during peck micro-drilling is related to the height of the burr occurring at the outlet of the drilled hole and the prefailure phase of micro-drills.

  1. 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.

  2. The wear properties and adhesion strength of the diamond-like carbon film coated on SUS, Ti and Ni-Ti with plasma pre-treatment.

    PubMed

    Ozeki, K; Masuzawa, T; Hirakuri, K K

    2010-01-01

    Diamond-like carbon (DLC) films were deposited on stainless steel (SUS), titanium (Ti) and nickel titanium (Ni-Ti) substrates using a radiofrequency plasma chemical vapour deposition method. Prior to DLC coating, the substrates were exposed to O2 and N2 plasma to enhance the adhesion strength of the DLC film to the substrate. After the plasma pre-treatment, the chemical composition and the wettability of the substrate surface was investigated by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement, respectively. A pull-out test and a ball-on-disc test were carried out to evaluate the adhesion strength and the wear properties of the DLC-coated substrates. The XPS results showed that the N2 and O2 plasma pre-treatment produced nitride and oxide on the substrate surfaces, such as TiO2, TiO, Fe2O3, CrN and TiNO. In the pull-out test, the adhesion strengths of the DLC film to the SUS, Ti and Ni-Ti substrates were improved with the plasma pre-treatment. In the ball-on-disc test, the DLC coated SUS, Ti and Ni-Ti substrates without the plasma pre-treatment showed severe film failure following the test. The DLC coated SUS and Ni-Ti substrates with the N2 plasma pre-treatment showed good wear resistance, compared with that with the O2 plasma pre-treatment. PMID:20448301

  3. Description of a unique machine tool permitting achievement of < 15-A rms diamond-turned surfaces

    SciTech Connect

    Miller, D.M.; Hauver, G.H.; Culverhouse, J.N.; Greenwell, E.N.

    1980-01-01

    A new machine tool now in the final stages of development at the Pacific Northwest Laboratory uses a unique tool motion to produce diamond-turned surfaces of exceptionally high quality. The cutting tool is programmed to move in 4-nm increments along two axes: an X axis and an Omega axis. Exceptionally stiff and accurate control of the tool is possible with this Omega-X system. Copper surfaces of revolution have been produced with a 12.3-A rms surface finish and a contour accuracy of 75 nm. In conjunction with a unique, thermally stabilized air bearing spindle and machine calibration equipment, the Omega-X system permits a significant advance in the fabrication of optical-quality surfaces for use with the visible spectrum.

  4. 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. PMID:26367879

  5. Diamond turning of lithium niobate for optical applications

    SciTech Connect

    Fuchs, B.A.; Syn, C.; Velsko, S.P. )

    1992-09-20

    We have investigated the surfae finishing of lithium niobate by using the single-point diamond turning technique. Surface finishes of better than 5 nm rms on {ital z}-oriented samples have been achieved. However, tool wear and spalling are much more significant with lithium niobate than with materials such as the crystals KDP and LAP. We present preliminary results comparing the optical damage thresholds of polished and diamond-turned samples.

  6. 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

  7. 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.

  8. Applying the self-organization feature map (SOM) algorithm to AE-based tool wear monitoring in micro-cutting

    NASA Astrophysics Data System (ADS)

    Yen, Chia-Liang; Lu, Ming-Chyuan; Chen, Jau-Liang

    2013-01-01

    This study applies a self-organization feature map (SOM) neural network to acoustic emission (AE) signal-based tool wear monitoring for a micro-milling process. An experiment was set up to collect the signal during cutting for the system development and performance analysis. The AE signal generated on the workpiece was first transformed to the frequency domain by Fast Fourier transformation (FFT), followed by feature extraction processing using the SOM algorithm. The performance verification in this study adopts a learning vector quantification (LVQ) network to evaluate the effects of the SOM algorithm on the classification performance for tool wear monitoring. To investigate the improvement achieved by the SOM algorithms, this study also investigates cases applying only the LVQ classifier and based on the class mean scatter feature selection (CMSFS) criterion and LVQ. Results show that accurate classification of the tool wear can be obtained by properly selecting features closely related to the tool wear based on the CMSFS and frequency resolution of spectral features. However, the SOM algorithms provide a more reliable methodology of reducing the effect on the system performance contributed by noise or variations in the cutting system.

  9. Laser Processing of Coarse Grain Polycrystalline Diamond (PCD) Cutting Tool Inserts using Picosecond Laser Pulses

    NASA Astrophysics Data System (ADS)

    Dold, C.; Henerichs, M.; Gilgen, P.; Wegener, K.

    Manufacturing of cutting edges in PCD cutting tool inserts (CTI) using picosecond pulsewidth laser sources is presented. Cutting edge radii of redge = 5 to 6 μm are achieved. Validation experiments are carried out on a turning lathe using lasered and ground CTI on machining carbon fibre reinforced plastics (CFRP) which is mainly used for aircraft structures. Experiments are done on fine and coarse grain PCD structures (average grain sizes are 2-4 μm and 25 μm resepectively) which are not economical in the latter case if manufactured conventionally, e.g. using grinding processes. Wear resistance, tool lifetime and process forces can be improved if laser processed coarse grain cutting tools are employed.

  10. SintClad: A New Approach for the Production of Wear-Resistant Tools

    NASA Astrophysics Data System (ADS)

    Blüm, M.; Hill, H.; Moll, H.; Weber, S.; Theisen, W.

    2012-05-01

    Tools used in the mineral processing industry are required to feature high wear resistance to facilitate an adequate cost efficiency. These kinds of tools are made of composite materials based on a low-alloyed substrate material and a high-alloyed coating. The coatings can be applied in different ways using production processes like HIP cladding, deposit welding, and composite casting. The article is concerned with the problem of a novel and cost-effective coating alternative: sinter cladding, using the principle of super-solidus liquid-phase sintering (SLPS). Usually SLPS represents a sintering technique, which is used for the compaction of high-alloyed metal powders. However, no recognizable efforts were made to use the SLPS-process for applying a PM-coating on a bulk substrate material. Sinter cladding for the first time uses SLPS to combine the process of powder compaction with the application of a coating to a solid steel substrate into one single step. Another advantage of the process is the possibility to produce massive bulk coatings with thicknesses exceeding 20 mm. This article is original in the scope of question and investigation methods in terms of microstructure, hardness profiles, EDX measurements, diffusion calculations, and computational thermodynamics.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. Use of slide presentation software as a tool to measure hip arthroplasty wear.

    PubMed

    Yun, Ho Hyun; Jajodia, Nirmal K; Myung, Jae Sung; Oh, Jong Keon; Park, Sang Won; Shon, Won Yong

    2009-12-01

    The authors propose a manual measurement method for wear in total hip arthroplasty (PowerPoint method) based on the well-known Microsoft PowerPoint software (Microsoft Corporation, Redmond, Wash). In addition, the accuracy and reproducibility of the devised method were quantified and compared with two methods previously described by Livermore and Dorr, and accuracies were determined at different degrees of wear. The 57 hips recruited were allocated to: class 1 (retrieval series), class 2 (clinical series), and class 3 (a repeat film analysis series). The PowerPoint method was found to have good reproducibility and to better detect wear differences between classes. The devised method can be easily used for recording wear at follow-up visits and could be used as a supplementary method when computerized methods cannot be employed. PMID:19896061

  16. Effect of deep cryogenic treatment on the formation of nano-sized carbides and the wear behavior of D2 tool steel

    NASA Astrophysics Data System (ADS)

    Amini, Kamran; Akhbarizadeh, Amin; Javadpour, Sirus

    2012-09-01

    The effect of deep cryogenic treatment on the microstructure, hardness, and wear behavior of D2 tool steel was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), hardness test, pin-on-disk wear test, and the reciprocating pin-on-flat wear test. The results show that deep cryogenic treatment eliminates retained austenite, makes a better carbide distribution, and increases the carbide content. Furthermore, some new nano-sized carbides form during the deep cryogenic treatment, thereby increasing the hardness and improving the wear behavior of the samples.

  17. Diamond cutters' grinders

    NASA Astrophysics Data System (ADS)

    Romanov, B. F.

    1985-03-01

    The development of diamond tool designs is determined by the development of the technology for the synthesis of artificial diamonds. The technology of syntehsizing artificial diamonds involves the production of mono and polycrystalline diamonds and composition diamond-containing materials. High strength and thermally stable monocrystalline diamonds brands AS30 to AS80 in a size of up to 800 micrometers, and polycrystalline diamonds: black diamonds, ballas (Synthetic Fiber) in a size up to 10mm, are manufactured. Production of single-layer and double-layer diamond plates used in cutting tools is organized. The raw materials base with the constant decrease in the use of natural diamonds is the basis for the development of the manufacture of a wide array of diamond tools. New areas of applications for tools using natural diamonds, such as diamond cutters for turning high-precision parts, straightening tools, hardness gages are outlined. Diamond cutters with natural diamonds are used to grind surfaces which have exceptionally high requirements with respect to the reflecting capacity and roughness.

  18. 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. PMID:15747185

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

    NASA Astrophysics Data System (ADS)

    Miller, Arthur C., Jr.; Cuttino, James F.

    1997-11-01

    This paper describes a new, fast tool servo system designed for fabrication of non-rotationally symmetric components using single point diamond turning machines. A prototype device, 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. 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 reduced using a dynamic compensator module in conjunction with a linear controller. The compensator samples the hysteretic voltage/displacement relationship in real time and modifies the effective gain accordingly. Simulation results indicate that errors in the performance of the system caused by hysteresis in the system can be compensated and reduced by 90 percent. Experimental implementation results in an 80 percent reduction in the 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. High-Temperature Sliding Wear Testing of Cathodic Arc Physical Vapor Deposition AlTiN- and AlTiON-Coated Hot Work Tool Steels

    NASA Astrophysics Data System (ADS)

    Birol, Yucel; Isler, Duygu; Urgen, Mustafa

    2011-11-01

    Thin hard coatings provide the much needed protection for steel thixoforming tools that must resist wear at high temperatures. The wear resistance of AlTiN- and AlTiON-coated hot work tool steel was investigated at 1023 K (750 °C), measured to be the cavity surface temperature shortly after the steel slurry was forced into the thixoforming die. The wear tests were repeated in exactly the same fashion with uncoated tool steel samples to identify the impact of AlTiN and AlTiON coatings on the high-temperature wear performance of X32CrMoV33 tool steel. The nature, the thickness, and the adherence of the oxide scales impact the tribological behavior. The poor adherence and limited ductility of ferrous oxides promote the failure of the oxide scale impairing the resistance to wear of the hot work tool steel at elevated temperatures. The substantial softening in the X32CrMoV33 hot work tool steel is also critical in the wear volume loss it suffers. AlTiN and AlTiON coatings, on the other hand, form a stable and protective oxide surface layer at high temperatures and therefore provide an enhanced resistance to oxidation. The latter is relatively more resistant to oxidation and is thus the better of the two coatings tested in the present work.

  5. 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. PMID:12662710

  6. On-machine precision preparation and dressing of ball-headed diamond wheel for the grinding of fused silica

    NASA Astrophysics Data System (ADS)

    Chen, Mingjun; Li, Ziang; Yu, Bo; Peng, Hui; Fang, Zhen

    2013-09-01

    In the grinding of high quality fused silica parts with complex surface or structure using ball-headed metal bonded diamond wheel with small diameter, the existing dressing methods are not suitable to dress the ball-headed diamond wheel precisely due to that they are either on-line in process dressing which may causes collision problem or without consideration for the effects of the tool setting error and electrode wear. An on-machine precision preparation and dressing method is proposed for ball-headed diamond wheel based on electrical discharge machining. By using this method the cylindrical diamond wheel with small diameter is manufactured to hemispherical-headed form. The obtained ball-headed diamond wheel is dressed after several grinding passes to recover geometrical accuracy and sharpness which is lost due to the wheel wear. A tool setting method based on high precision optical system is presented to reduce the wheel center setting error and dimension error. The effect of electrode tool wear is investigated by electrical dressing experiments, and the electrode tool wear compensation model is established based on the experimental results which show that the value of wear ratio coefficient K' tends to be constant with the increasing of the feed length of electrode and the mean value of K' is 0.156. Grinding experiments of fused silica are carried out on a test bench to evaluate the performance of the preparation and dressing method. The experimental results show that the surface roughness of the finished workpiece is 0.03 μm. The effect of the grinding parameter and dressing frequency on the surface roughness is investigated based on the measurement results of the surface roughness. This research provides an on-machine preparation and dressing method for ball-headed metal bonded diamond wheel used in the grinding of fused silica, which provides a solution to the tool setting method and the effect of electrode tool wear.

  7. Proposed method of producing large optical mirrors Single-point diamond crushing followed by polishing with a small-area tool

    NASA Technical Reports Server (NTRS)

    Wright, G.; Bryan, J. B.

    1986-01-01

    Faster production of large optical mirrors may result from combining single-point diamond crushing of the glass with polishing using a small area tool to smooth the surface and remove the damaged layer. Diamond crushing allows a surface contour accurate to 0.5 microns to be generated, and the small area computer-controlled polishing tool allows the surface roughness to be removed without destroying the initial contour. Final contours with an accuracy of 0.04 microns have been achieved.

  8. 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.

  9. Cutting force-based real-time estimation of tool wear in face milling using a combination of signal processing techniques

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, P.; Sengupta, D.; Mukhopadhyay, S.

    2007-08-01

    In this paper, combinations of signal processing techniques for real-time estimation of tool wear in face milling using cutting force signals are presented. Three different strategies based on linear filtering, time-domain averaging and wavelet transformation techniques are adopted for extracting relevant features from the measured signals. Sensor fusion at feature level is used in search of an improved and robust tool wear model. Isotonic regression and exponential smoothing techniques are introduced to enforce monotonicity and smoothness of the extracted features. At the first stage, multiple linear regression models are developed for specific cutting conditions using the extracted features. The best features are identified on the basis of a statistical model selection criterion. At the second stage, the first-stage models are combined, in accordance with proven theory, into a single tool wear model, including the effect of cutting parameters. The three chosen strategies show improvements over those reported in the literature, in the case of training data as well as test data used for validation—for both laboratory and industrial experiments. A method for calculating the probabilistic worst-case prediction of tool wear is also developed for the final tool wear model.

  10. Continued force wear and part correction experiments

    SciTech Connect

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

    1995-12-31

    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.

  11. Single point diamond crushing of glass

    SciTech Connect

    Bryan, J.B.; Carter, D.L.; Clouser, R.W.; Thompson, S.L.

    1984-05-23

    Single point diamond crushing of glass was originally developed by Dr. R.E. Reason of Taylor and Hobson in England 34 years ago as a means of shaping glass aspheres prior to polishing. It has recently been tried at LLNL. A surface finish of 50 microinches peak-to-valley with occasional deeper pits has been achieved on Zerodur and BK-7 glass. A depth of cut of 0.008 inch or more can be taken at a surface speed of 900 feet per minute. Tool wear is on the order of 10 microinches after removal of one cubic inch of Zerodur. The tool's cost is $5.45 each.

  12. 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.

  13. 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.

  14. 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

  15. Simulation and Experimental Studies on Substrate Temperature and Gas Density Field in Hfcvd Diamond Films Growth on WC-Co Drill Tools

    NASA Astrophysics Data System (ADS)

    Zhang, Jianguo; Zhang, Tao; Wang, Xinchang; Shen, Bin; Sun, Fanghong

    2013-04-01

    Uniform temperature and gas density field inside the reactor play an important role on synthesis of high-quality diamond films using hot filament chemical vapor deposition (HFCVD) method. In the present study, the finite volume method (FVM) is adopted to simulate the temperature and gas density distribution during the deposition process. Temperature-measuring experiments are conducted to verify the correctness of the simulation results. Thereafter, the deposition parameters are optimized using this model as D (filament separation) = 35 mm, H (filament-substrate distance) = -10 mm and N (number of gas inlet) = 3. Finally, experiments of depositing diamond films on WC-Co drill tools are carried out with the optimal deposition parameters. The results of the characterization by SEM and Raman spectrum exhibit that as-fabricated diamond-coated tools present a layer of high-quality diamond films with homogeneous surface and uniform thickness, further validating the accuracy of the parameter optimization using the simulation method.

  16. 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.

  17. 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.

  18. 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

  19. 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…

  20. 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.

  1. Measurement of friction and wear

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1978-01-01

    Report reviews various techniques and surface tools available for study of wear of materials. Atomic nature of solid surfaces plays important role in wear behavior for materials in solid-state contact.

  2. Characterization of tool wear and weld optimization in the friction-stir welding of cast aluminum 359+20% SiC metal-matrix composite

    SciTech Connect

    Fernandez, G.J.; Murr, L.E

    2004-03-15

    Tool wear for threaded steel pin tools declines with decreasing rotation speed and increasing traverse or weld speeds for the friction-stir welding (FSW) of Al 359+20% SiC metal-matrix composite (MMC). Less than 10% tool wear occurs when the threaded tool erodes to a self-optimized shape resembling a pseudo-hour glass at weld traverse distances in excess of 3 m. There is only a 7% reduction in the SiC mean particle size in the weld zone for self-optimized pin tools with no threads as compared with a 25% variation for threaded tools wearing significantly at the start of welding. The weld zone becomes more homogeneous for efficient welding with self-optimized tools, and there is a reduction in the weld zone grain size due to dynamic recrystallization, which facilitates the solid-state flow. Transmission electron microscopy shows little difference in the dislocation density from the base material to the weld zone, but there is a propensity of dislocation loops in the weld zone. The weld zone is observed to harden by as much as 30%, in contrast to the base material, as a consequence of the recrystallized grain size reduction and the SiC particles distributed therein.

  3. 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

    2016-04-01

    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.

  4. 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.

  5. 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

  6. 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.

  7. Advance leads to new diamond coatings applications

    SciTech Connect

    Cederquist, S.C.

    1999-06-01

    a significant advance in producing wear-resistant coatings has been achieved by scientists at the US Department of Energy's Sandia National Laboratories (SNL) (Albuquerque, New Mexico) through the discovery of a stress-free amorphous (noncrystalline) diamond thin film material that has many of the same properties as its crystalline diamond cousin. The stress-free amorphous diamond coating is harder than any other known coating--with the exception of crystalline diamond. Crystalline diamond films are difficult to grow, and even harder to shape into parts. Thin films of amorphous diamond offer some flexibility, but are associated with problems like warping.

  8. 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.

  9. Effect of Al2O3 nanolubrication with Sodium Dodecylbenzene Sulfonate (SDBS) on surface roughness and tool wear under MQL during turning of Ti-6AL-4T.

    NASA Astrophysics Data System (ADS)

    Ali, M. A. M.; Khalil, A. N. M.; Azmi, A. I.

    2016-02-01

    The application of coolant reduces the friction and heat generation, which affect the surface finish and tool life, during machining. Recently, nanolubricant opens a new ways of coolant strategy in machining operation. It is well known that suspended nanoparticles without surfactant in base oil tend to agglomerate after a period of time. This paper presents the effects of AEO3 nanolubricant with surfactant, Sodium Dodecylbenzene Sulfonate (SDBS) on surface roughness and tool wear during turning of titanium alloy, Ti-6AL-4T. The comparison of different coolant strategies, dry cutting, flooding, minimum quantity lubricant (MQL), nanolubricant with and without surfactant are also presented. The results showed that Al2O3 nanolubricant with surfactant, Sodium Dodecylbenzene Sulfonate (SDBS) under MQL exhibits low surface roughness and tool wear rate compared to others. This proved that the addition of surfactant not only improved nanolubricant stability but also machining performance.

  10. 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.

  11. 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

  12. Scanning tunneling microscopy-based in situ measurement of fast tool servo-assisted diamond turning micro-structures

    NASA Astrophysics Data System (ADS)

    Ju, Bing-Feng; Zhu, Wu-Le; Yang, Shunyao; Yang, Keji

    2014-05-01

    We propose a new in situ measurement system based on scanning tunneling microscopy (STM) to realize spiral scanning of a micro-structure without removing it after fast tool servo (FTS) cutting. To avoid distortion of the machined and measured surface, the center alignment of the FTS tool and the STM tip was first implemented by an STM in situ raster scan of two circular grooves cut by the machine tool. To originally observe the machined surface, the trace of the STM tip is put in accord with that of the FTS by setting the same start and end points of cutting and scanning and the same feed rate, and both are triggered by the subdivided rotary encoder of the spindle of the diamond turning machine. The profile data of the in situ spiral scanning of the machined micro-lens array can be fed back to compensate the depth of the cut to guarantee sub-micron form accuracy after second machining. The efficient spiral scanning, proper matching and accurate evaluation results demonstrate that the proposed STM in situ measurement approach is of great significance to the fabrication process.

  13. 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.

  14. Modeling and Simulation of a Donor Material Concept to Reduce Tool Wear in Friction Stir Welding of High-Strength Materials

    NASA Astrophysics Data System (ADS)

    Mandal, S.; Rice, J.; Hou, G.; Williamson, K. M.; Elmustafa, A. A.

    2013-06-01

    This research proposes the "donor material" concept for reduction of tool's wear at the plunge phase by providing localized preheating at the plunge area using a softer material as a "donor." This process generates heat in a relatively soft "donor" material, which is transferred to the much harder workpiece material by conduction. This research includes several numerical simulations of the donor material concept with different donor materials and plain carbon steel as the workpiece. A Significant decreases in both axial force and contact pressure were observed when a donor material was used in the plunge area. The decreases in both axial force and contact pressure are very likely to contribute to decreasing tool's wear.

  15. Films Composed Of Diamond And Diamondlike Carbon

    NASA Technical Reports Server (NTRS)

    Shing, Yuh-Han

    1995-01-01

    Proposed films composed of diamond and diamondlike carbon useful as wear-resistant and self-lubricating protective and tribological coats at extreme temperatures and in corrosive and oxidizing environments. Films have wide variety of industrial applications.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Single Point Diamond Turning of Glass

    NASA Astrophysics Data System (ADS)

    Blough, Christian Gary

    1992-01-01

    The feasibility of single point diamond turning optical quality glass surfaces has been experimentally studied. The main objective of the research is to study the ductile removal process of glass and identify the important parameters. By investigating several optical glasses and varying different machining variables, a matrix of the important parameters has been generated. A precision lathe capable of ductile machining glass has been assembled by adding a nano-positioning toolholder to an existing machine. The toolholder enables the structural loop between the tool and workpiece to be effectively closed. Using a proximity sensor and analog electronics, a feedback loop has been constructed that increases the rigidity, thermal stability, and tool positioning accuracy of the existing machine. With the closed loop system, the tool positioning resolution is 15 nm and the effective structural loop stiffness is 1.75 times 10^3 N/mum. The closed loop system has been verified by machining a circular grating in germanium to within 3 nm of its theoretical form. The ductile machining of glass was limited by one key variable, tool edge wear. For every glass investigated, except FCD1, there was nearly instantaneous catastrophic loss of the cutting edge due to oxidation and/or graphitization of the diamond.

  1. 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

  2. Applications of diamond films and related materials; Proceedings of the 1st International Conference, Auburn, AL, Aug. 17-22, 1991

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua (Editor); Yoshikawa, Manasori (Editor); Murakawa, Masao (Editor); Feldman, Albert (Editor)

    1991-01-01

    The present conference discusses the nucleation and growth of diamond from hydrocarbons, the cutting tool performance of CVD thick-film diamond, the characterization of CVD diamond grinding powder, industrial applications of crystalline diamond-coated tools, standardized SEM tribometry of diamond-coated substrates, residual stress in CVD diamond films, the optical properties of CVD diamond films, polycrystalline diamond films for optical applications, and diamond growth on ferrous metals. Also discussed are ion beam-irradiation smoothing of diamond films, electronic circuits on diamond substrates, diamond-laminated surfaces for evaporative spray cooling, electron devices based on the unique properties of diamond, diamond cold cathodes, thin-film diamond microstructure applications, Schottky diodes from flame-grown diamond, diamond films for thermionic applications, methods of diamond nucleation and selective deposition, high-rate/large-area diamond film production, halogen-assisted diamond growth, the economics of diamond technology, and the optical and mechanical properties of diamondlike films.

  3. 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.

  4. FPGA-based fused smart-sensor for tool-wear area quantitative estimation in CNC machine inserts.

    PubMed

    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

  5. 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

  6. 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.

  7. Direct Coating of Nanocrystalline Diamond on Steel

    NASA Astrophysics Data System (ADS)

    Tsugawa, Kazuo; Kawaki, Shyunsuke; Ishihara, Masatou; Hasegawa, Masataka

    2012-09-01

    Nanocrystalline diamond films have been successfully deposited on stainless steel substrates without any substrate pretreatments to promote diamond nucleation, including the formation of interlayers. A low-temperature growth technique, 400 °C or lower, in microwave plasma chemical vapor deposition using a surface-wave plasma has cleared up problems in diamond growth on ferrous materials, such as the surface graphitization, long incubation time, substrate softening, and poor adhesion. The deposited nanocrystalline diamond films on stainless steel exhibit good adhesion and tribological properties, such as a high wear resistance, a low friction coefficient, and a low aggression strength, at room temperature in air without lubrication.

  8. Functionally gradient hard carbon composites for improved adhesion and wear

    NASA Astrophysics Data System (ADS)

    Narayan, Roger Jagdish

    A new approach is proposed for fabricating biomedical devices that last longer and are more biocompatible than those presently available. In this approach, a bulk material is chosen that has desirable mechanical properties (low modulus, high strength, high ductility and high fatigue strength). This material is coated with corrosion-resistant, wear-resistant, hard, and biocompatible hard carbon films. One of the many forms of carbon, tetrahedral amorphous carbon, consists mainly of sp3-bonded atoms. Tetrahedral amorphous carbon possesses properties close to diamond in terms of hardness, atomic smoothness, and inertness. Tetrahedral amorphous carbon and diamond films usually contain large amounts of compressive and sometimes tensile stresses; adhesive failure from these stresses has limited widespread use of these materials. This research involves processing, characterization and modeling of functionally gradient tetrahedral amorphous carbon and diamond composite films on metals (cobalt-chromium and titanium alloys) and polymers (polymethylmethacrylate and polyethylene) used in biomedical applications. Multilayer discontinuous thin films of titanium carbide, titanium nitride, aluminum nitride, and tungsten carbide have been developed to control stresses and graphitization in diamond films. A morphology of randomly interconnected micron sized diamond crystallites provides increased toughness and stress reduction. Internal stresses in tetrahedral amorphous carbon were reduced via incorporation of carbide forming elements (silicon and titanium) and noncarbide forming elements (copper, platinum, and silver). These materials were produced using a novel target design during pulsed laser deposition. These alloying atoms reduce hardness and sp3-bonded carbon content, but increase adhesion and wear resistance. Silver and platinum provide the films with antimicrobial properties, and silicon provides bioactivity and aids bone formation. Bilayer coatings were created that couple

  9. 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

  10. Experimental study of the diamond turning characteristics of tungsten carbide (Co 0.5%) when using a chamfered diamond bite

    NASA Astrophysics Data System (ADS)

    Kim, Min Jae; Lee, June Key; Hwang, Yeon; Cha, Du Hwan; Kim, Hye Jeong; Kim, Jeong Ho

    2012-11-01

    Tungsten carbide (WC) is a widely used as a mold material for fabrication of glass lens because of its superior properties. Due to its extremely high hardness (R c > 90), an abrasive machining process, although unproductive and expensive, is used to fabricate the mold. In this research, the authors investigated the machining possibility of tungsten carbide by single-point diamond turning (SPDT) for fabricating high-quality optical surfaces directly. A finite element analysis (FEA) was carried out in order to investigate the effects of the chamfered length on the cutting forces and the strain rate of single-crystal diamond tools. The obtained FEA results showed that a smaller chamfered length decreased the bite strain rate. The performance characteristics in terms of surface roughness (R a ) and tool wear (VB max ) of a conventional bite and a chamfered bite under same machining conditions were studied, the results were compared. Experimental results suggest that the chamfered bite wased a better performance than the conventional bite in terms of tool wear resistance. The WC surface machined by using the chamfered bite showed a 2.26 nm roughness (R a ), which is suitable for the fabrication of glass lenses.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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. 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.

  14. Eye Wear

    MedlinePlus

    Eye wear protects or corrects your vision. Examples are Sunglasses Safety goggles Glasses (also called eyeglasses) Contact ... jobs and some sports carry a risk of eye injury. Thousands of children and adults get eye ...

  15. 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.

  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.

    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.

  18. 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.

  19. Electrodeposited coatings for diamond turning applications

    SciTech Connect

    Mayer, A.; Bramlett, R.D.; Day, R.D. ); Evans, C.J.; Polvani, R.S. )

    1991-01-01

    Electrodeposited coatings are attractive for precision machining operations because thick coatings can be economically applied, with good adhesion, to a variety of substrates. Approximately 20 pure metals and a large number of alloys can be deposited from aqueous solutions. Fused salt and organic solvent electrolytes can be used to lengthen the list of metals that can be electrodeposited. However, both the choice of the metallic coating and the control of the plating process are critical for success in precision finishing of electrodeposited coatings. Some preliminary results at the National Institute of Standards and Technology and at the Lawrence Livermore National Laboratory suggest that electrodeposited nickel-phosphorus alloys are excellent coatings for single point diamond turning from the standpoint of material properties and low tool wear. Electrodeposited aluminum and aluminum alloy coatings also merit consideration for precision finishing where weight is an important factor. 10 refs., 6 figs.

  20. Diamond turning of L-arginine phosphate, a new organic crystal

    SciTech Connect

    Fuchs, B.A.; Syn, K.; Velsko, S.P. )

    1989-10-15

    We have demonstrated that single point diamond turning can be used to generate high optical quality finished surfaces on a new organic nonlinear crystal, L-arginine phosphate (LAP). The proper choice of cutting conditions can produce surfaces with {lt}5-A rms local roughness. Local softening or melting near the cutting tool tip may play a key role in the machining process by ensuring that material is removed by ductile cutting rather than brittle fracture. At the same time, the low melting temperature of LAP makes lubrication and cooling especially important to prevent extensive melting and tool fouling. In spite of the presence of a weak cleavage plane in LAP, the surface quality is relatively insensitive to crystallographic orientation. Tool wear is apparently negligible, so that surface flatness is governed by the stability of the diamond turning machine. These results suggest that it may be possible to fabricate large aperture LAP harmonic converters for use in inertial confinement fusion lasers.

  1. 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

  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. 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.

  4. Optimization of Cvd Diamond Coating Type on Micro Drills in Pcb Machining

    NASA Astrophysics Data System (ADS)

    Lei, X. L.; He, Y.; Sun, F. H.

    2016-12-01

    The demand for better tools for machining printed circuit boards (PCBs) is increasing due to the extensive usage of these boards in digital electronic products. This paper is aimed at optimizing coating type on micro drills in order to extend their lifetime in PCB machining. First, the tribotests involving micro crystalline diamond (MCD), nano crystalline diamond (NCD) and bare tungsten carbide (WC-Co) against PCBs show that NCD-PCB tribopair exhibits the lowest friction coefficient (0.35) due to the unique nano structure and low surface roughness of NCD films. Thereafter, the dry machining performance of the MCD- and NCD-coated micro drills on PCBs is systematically studied, using diamond-like coating (DLC) and TiAlN-coated micro drills as comparison. The experiments show that the working lives of these micro drills can be ranked as: NCD>TiAlN>DLC>MCD>bare WC-Co. The superior cutting performance of NCD-coated micro drills in terms of the lowest flank wear growth rate, no tool degradation (e.g. chipping, tool tipping) appearance, the best hole quality as well as the lowest feed force may come from the excellent wear resistance, lower friction coefficient against PCB as well as the high adhesive strength on the underneath substrate of NCD films.

  5. 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.

  6. Effect of micro/nano-scale textures on anti-adhesive wear properties of WC/Co-based TiAlN coated tools in AISI 316 austenitic stainless steel cutting

    NASA Astrophysics Data System (ADS)

    Zhang, Kedong; Deng, Jianxin; Sun, Jialin; Jiang, Chao; Liu, Yayun; Chen, Shuai

    2015-11-01

    In cutting of stainless steel with coated tool, the steel chip adhering to tool surface is usually severe and consequently causes serious adhesive and frictional problems, which is the major reason for the failure of coated tool. To solve the problem, a surface engineering approach, namely, a highly functionalization of tool surfaces by textures may be of great importance. Thus, the effect of micro/nano-scale textures on anti-adhesive wear properties of TiAlN coated tools in AISI 316 austenitic stainless steel cutting was investigated. For this purpose, two types of surface textures were fabricated on the rake faces of WC/Co carbide tools: (i) micro-scale textures fabricated by Nd:YAG laser, (ii) micro/nano-scales textures fabricated by Nd:YAG laser and femtosecond laser. Then, these textured tools were deposited with TiAlN coatings using cathode arc-evaporation technique. Wet cutting experiments were carried out with the micro-scale textured coated tool (MCT), micro/nano-scale textured coated tool (MNCT), and the conventional coated tool (CCT). Results obtained in this work demonstrated the feasibility of fabricating micro- or micro/nano-scale textures on tools substrate surfaces to improve the anti-adhesive wear properties of TiAlN coated tool. The rake face micro/nano-scale textured tool was the most effective. Moreover, mechanisms for the anti-adhesive properties enhancement were proposed.

  7. How dislocations and grain boundaries control wear at the nanoscale

    NASA Astrophysics Data System (ADS)

    Szlufarska, Izabela

    2012-02-01

    Ceramics show outstanding mechanical properties such as high strength and high hardness over a wide range of temperatures and are stable in harsh environments. However, the low fracture toughness of ceramics limits their practical utility for instance as wear-resistance coatings. There have been several reports of improving wear resistance of ceramics by reducing the grain sizes and/or the dimension of the cutting tools to the nanometer regime. Using SiC as a model covalent ceramic, we performed molecular dynamics (MD) simulations of wear for both single crystal and nanocrystalline material. We determined the role of dislocations and grain boundary sliding in improving wear resistance of SiC and we have quantified contributions from these mechanisms to friction and wear. We have discovered instabilities that control sliding of the amorphous-like highly disordered grain boundaries in SiC, in analogy to instabilities and deformation mechanisms that occur in bulk amorphous materials. In this talk we will also present our newly developed analytical model for plowing friction in nanoscale contacts, which model has been validated for both ceramics and metals. In order to isolate the contribution from grain boundary sliding to deformation of nanocrystalline materials, we have performed MD simulations of nanoindentation and uniaxial testing on ultrananocrystalline diamond (UNCD). We have shown that in the absence of dislocation plasticity, hardness and yield strength of nanocrystalline materials scale linearly with the grain boundary shear strength, where the latter property can be controlled by grain boundary doping. Our findings explain the experimental observations that hardness and elastic properties of UNCD decrease with an increasing H content.

  8. Friction Stir Welding of HSLA-65 Steel: Part II. The Influence of Weld Speed and Tool Material on the Residual Stress Distribution and Tool Wear

    NASA Astrophysics Data System (ADS)

    Steuwer, A.; Barnes, S. J.; Altenkirch, J.; Johnson, R.; Withers, P. J.

    2012-07-01

    A set of single pass full penetration friction stir bead-on-plate and butt welds in HSLA-65 steel were produced using a range of traverse speeds (50 to 500 mm/min) and two tool materials (W-Re and PCBN). Part I described the influence of process and tool parameters on the microstructure in the weld region. This article focuses on the influence of these parameters on residual stress, but the presence of retained austenite evident in the diffraction pattern and X-ray tomographic investigations of tool material depositions are also discussed. The residual stress measurements were made using white beam synchrotron X-ray diffraction (SXRD). The residual stresses are affected by the traverse speed as well as the weld tool material. While the peak residual stress at the tool shoulders remained largely unchanged (approximately equal to the nominal yield stress (450 MPa)) irrespective of weld speed or tool type, for the W-Re welds, the width of the tensile section of the residual stress profile decreased with increasing traverse speed (thus decreasing line energy). The effect of increasing traverse speed on the width of the tensile zone was much less pronounced for the PCBN tool material.

  9. 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.

  10. 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.

  11. 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.

  12. 3D FEM Simulation of Flank Wear in Turning

    NASA Astrophysics Data System (ADS)

    Attanasio, Aldo; Ceretti, Elisabetta; Giardini, Claudio

    2011-05-01

    This work deals with tool wear simulation. Studying the influence of tool wear on tool life, tool substitution policy and influence on final part quality, surface integrity, cutting forces and power consumption it is important to reduce the global process costs. Adhesion, abrasion, erosion, diffusion, corrosion and fracture are some of the phenomena responsible of the tool wear depending on the selected cutting parameters: cutting velocity, feed rate, depth of cut, …. In some cases these wear mechanisms are described by analytical models as a function of process variables (temperature, pressure and sliding velocity along the cutting surface). These analytical models are suitable to be implemented in FEM codes and they can be utilized to simulate the tool wear. In the present paper a commercial 3D FEM software has been customized to simulate the tool wear during turning operations when cutting AISI 1045 carbon steel with uncoated tungsten carbide tip. The FEM software was improved by means of a suitable subroutine able to modify the tool geometry on the basis of the estimated tool wear as the simulation goes on. Since for the considered couple of tool-workpiece material the main phenomena generating wear are the abrasive and the diffusive ones, the tool wear model implemented into the subroutine was obtained as combination between the Usui's and the Takeyama and Murata's models. A comparison between experimental and simulated flank tool wear curves is reported demonstrating that it is possible to simulate the tool wear development.

  13. 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.

  14. 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.

  15. Surface finish in ultra-precision diamond turning of single-crystal silicon

    NASA Astrophysics Data System (ADS)

    Ayomoh, M.; Abou-El-Hossein, K.

    2015-10-01

    Silicon is an optical material widely used in the production of infrared optics. However, silicon as a brittle material exhibits some difficulties when ultra-precision machined by mono-crystalline single point diamond. Finish turning of silicon with mono- crystalline diamond inserts results in accelerated tool wear rates if the right combination of the machining parameters is not properly selected. In this study, we conducted a series of machining tests on an ultra-high precision machine tool using finish turning conditions when using mono-crystalline diamond inserts with negative rake angle and relatively big nose radius. The study yields some recommendations on the best combination of machining parameters that will result in maximum material removal rates with smallest possible surface finish. In this work, standard non-controlled waviness diamond inserts having nose radius of about 1.5 mm, rake angle of negative 25°, and clearance angle of 5° were used to produce flat surfaces on silicon disk. From the results, it has been established that feed rate has the most influential effect followed by the depth of cut and cutting speed.

  16. 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.

  17. 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.

  18. 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

  19. Determination of significant variables in compound wear using a statistical model

    SciTech Connect

    Pumwa, J.; Griffin, R.B.; Smith, C.M.

    1997-07-01

    This paper will report on a study of dry compound wear of normalized 1018 steel on A2 tool steel. Compound wear is a combination of sliding and impact wear. The compound wear machine consisted of an A2 tool steel wear plate that could be rotated, and an indentor head that held the 1018 carbon steel wear pins. The variables in the system were the rpm of the wear plate, the force with which the indentor strikes the wear plate, and the frequency with which the indentor strikes the wear plate. A statistically designed experiment was used to analyze the effects of the different variables on the compound wear process. The model developed showed that wear could be reasonably well predicted using a defined variable that was called the workrate. The paper will discuss the results of the modeling and the metallurgical changes that occurred at the indentor interface, with the wear plate, during the wear process.

  20. 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.

  1. '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.

  2. Wear resistance of ductile irons

    SciTech Connect

    Lerner, Y.S. )

    1994-06-01

    This study was undertaken to evaluate the wear resistance of different grades of ductile iron as alternatives to high-tensile-strength alloyed and inoculated gray irons and bronzes for machine-tool and high-pressure hydraulic components. Special test methods were employed to simulate typical conditions of reciprocating sliding wear with and without abrasive-contaminated lubricant for machine and press guideways. Quantitative relationships were established among wear rate, microstructure and microhardness of structural constituents, and nodule size of ductile iron. The frictional wear resistance of ductile iron as a bearing material was tested with hardened steel shafts using standard test techniques under continuous rotating movement with lubricant. Lubricant sliding wear tests on specimens and components for hydraulic equipment and apparatus were carried out on a special rig with reciprocating motion, simulating the working conditions in a piston/cylindrical unit in a pressure range from 5 to 32 MPa. Rig and field tests on machine-tool components and units and on hydraulic parts have confirmed the test data.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. High Temperature Tribological Properties of Modified Nano-diamond Additive in Lubricating Oil

    NASA Astrophysics Data System (ADS)

    Sun, X. F.; Qiao, Y. L.; Song, W.; Ma, S. N.; Hu, C. H.

    The high temperature tribological properties of surface-modified nano-diamond in colza oil were tested with SRV machine, and wear surface morphology was observed by using three dimension profiler. The results show that the modified nano-diamond by dimer ester possesses excellent anti-wear and friction reducing properties as lubricating oil additive. The friction coefficients of the modified nano-diamond by dimer ester are lower than those of nano-daimond and the modified nano-diamond by oleic ester when the temperature is lower than 200 °C, and its friction coefficients are very similar to nano-diamond's when the temperature is higher than 200 °C, but are better than that of the modified nano-diamond by oleic ester. The wear volume of the modified nano-diamond by dimer ester is far-forth lower than that of nano-daimond and the modified nano-diamond by oleic ester after the continuously heating test, and the wear volume decrease 60% than nano-diamond's.

  8. Wear resistance of boron nitride coated metal

    NASA Astrophysics Data System (ADS)

    Andoh, Yasunori; Nishiyama, Satoshi; Sakai, Shigeki; Ogata, Kiyoshi; Fujimoto, Fuminori

    1993-06-01

    The wear resistance of boron nitride films was studied. The films of 1 μm thickness were prepared on the surface of a cutting tool by simultaneous nitrogen ion irradiation and vapor depositon of boron; the Vickers hardness of the films was between 3000 and 5000 kg/mm 2. The test was performed by the cutting of steel. On the tool deposited directly, the wear of the surface is large and this could not be improved greatly. However, the tools prepared after nitridation of the surface layer by ion implantation and the one with another nitride layer in the interface showed decreasing wear, and the wear of the tool with an interlayer of silicon nitride could be decreased to about 15%. As a result, it became clear that boron nitride could be effectively used as a highly hard film by the optimization of the interface between the film and the matrix.

  9. Effect of reinforcement particle size on the tribological properties of nano-diamond filled polytetrafluoroethylene based coating.

    PubMed

    Lim, D P; Lee, J Y; Lim, D S; Ahn, S G; Lyo, I W

    2009-07-01

    The tribological properties of PTFE composite coatings reinforced by nano-diamonds were investigated. Mechanical particle size reduction and dispersion of nano-diamond aggregates were performed by milling with ceramic beads in an organic solvent. Particle size was controlled by the milling time. Pastes comprising a PTFE solution mixed with nano-diamond having various sizes were coated on the aluminum substrate. Ball-on-plate type wear test was performed to investigate the friction and wear behavior. The results indicated that the addition of nano-diamonds effectively improved tribological performance of the PTFE coating. The reduction in nano-diamond sizes were not always improved the wear resistance of PTFE coating. This unexpected behavior was explained by observation on the worn surfaces and wear debris. PMID:19916429

  10. 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.

  11. 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.

  12. Study of ultra-precision diamond turning of a microlens array with a fast tool servo system

    NASA Astrophysics Data System (ADS)

    To, S.; Kwok, T. C.; Cheung, C. F.; Lee, W. B.

    2006-02-01

    A Microlens array is a critical component for optimizing display functions. With the increasing usage of display systems in photonic products nowadays, more attention is being paid to the research and development of fabrication technology for microlens arrays. Ultra-precision machining with a fast tool servo (FTS) is one of the leading methodologies for fabrication of high-quality optical microstructural surfaces. FTS is an independently operated positioning device, which provides an indispensable solution for machining optical microstructures with sub-micrometer form accuracy and nanometric surface finish, without the need for any subsequent post processing. The surface quality of an FTS machined surface depends largely on the selection of cutting conditions. However, the achievement of ultra-precision surface finishing depends greatly on the experience and skill of the machine operators. Determination of optimal cutting conditions can stabilize the quality of the fabricated microlens array. In this paper, the effect of cutting conditions such as depth of cut, feed rate, spindle speed and surface speed are investigated; and optimal surface roughness and surface profiles in ultra-precision machining with FTS can be observed.

  13. 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

  14. FIBROUS MONOLITH WEAR RESISTANT COMPONENTS FOR THE MINING INDUSTRY

    SciTech Connect

    Mark J. Rigali

    2001-08-15

    A set of materials property data for potential wear resistant materials was collected. These materials are designated for use as the ''core'' materials in the Fibrous Monolith structure. The material properties of hardness, toughness, thermal conductivity and cost were selected as determining factors for material choice. Data for these four properties were normalized, and weighting factors were assigned for each property to establish priority and evaluate the effects of priority fluctuation. Materials were then given a score based on the normalized parameters and weighting values. Using the initial estimates for parameter priority, the highest ranking material was tungsten carbide, with diamond as the second ranked material. Several materials were included in the trade study, and five were selected as promising ''core'' materials to include in this effort. These materials are tungsten carbide, diamond, boron carbide, titanium diboride and silicon carbide. Work was initiated on a trade study to evaluate ''shell'' materials. These materials will require the investigation of different material properties, including ultimate tensile strength, ductility, toughness, thermal expansion, thermal conductivity and compatibility during consolidation with the ''core'' materials. Kyocera Industrial Ceramics in Kyoto, Japan was visited, with the purpose of negotiating and signing the subcontract for Kyocera's participation on this program. An assessment was made on the testing and manufacturing capabilities of Kyocera and how such capabilities can be integrated into our development effort. Tours were conducted of Kyocera's machine tool production plant in Sendai, Japan, as well as their research and development facilities in Kagoshima, Japan. Kyocera's facilities include substantial materials characterization and testing capabilities at room and elevated temperatures, and manufacturing capabilities of thousands of parts/hr, all of which will be made available to us for use on

  15. 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.

  16. Direct diamond turning of steel molds for optical replication

    NASA Astrophysics Data System (ADS)

    Klocke, Fritz; Dambon, Olaf; Bulla, Benjamin; Heselhaus, Michael

    2009-05-01

    In this paper the most recent investigations in ultrasonic assisted diamond machining of hardened steel at the Fraunhofer IPT is presented. The goal of this technology is to unify the outrageous specifications of diamond machining process with steel material. The focus lies on the kinematic influence of the discrete frequencies 40 kHz and 60 kHz. Special interest is given to the reachable surface roughness depending on process parameters. The machined steel (1.2083, X40Cr14, STAVAX ESU) is a common mold die material for optical replication processes.Results of the accomplished investigations show the potential of the ultrasonic assisted process and recent developments. By increasing the frequency from 40 kHz to 60 kHz the overall process stability is increased. This makes the process less vulnerable towards feed rate variation or towards the variation of machined material hardness. Furthermore no tool wear is detected at high material removal rates or high cutting distances during component machining.

  17. 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

  18. 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

  19. Spectroscopic wear detector

    NASA Technical Reports Server (NTRS)

    Madzsar, George C. (Inventor)

    1993-01-01

    The elemental composition of a material exposed to hot gases and subjected to wear is determined. Atoms of an elemental species not appearing in this material are implanted in a surface at a depth based on the maximum allowable wear. The exhaust gases are spectroscopically monitored to determine the exposure of these atoms when the maximum allowable wear is reached.

  20. Morphological response of diamond films in dry sliding contact

    NASA Astrophysics Data System (ADS)

    Languell, M. L.; George, M. A.; Wert, J. J.; Davidson, T. L.

    1994-07-01

    Reciprocating dry sliding friction tests performed on diamond-coated tungsten substrates produced changes in the surface morphology. A right-cylinder-on-flat geometry was used for the tribotesting. The morphological changes were investigated with scanning electron and atomic force microscopy. The composition of the diamond film was determined with Raman spectroscopy. The frictional response of the coating is examined in relation to the surface changes. A wear model for diamond films in dry sliding contact based on the morphological response is presented.

  1. Diamond stabilization of ice multilayers at human body temperature

    NASA Astrophysics Data System (ADS)

    Wissner-Gross, Alexander D.; Kaxiras, Efthimios

    2007-08-01

    Diamond is a promising material for wear-resistant medical coatings. Here we report a remarkable increase in the melting point of ice resting on a diamond (111) surface modified with a submonolayer of Na+ . Our molecular dynamics simulations show that the interfacial ice bilayer melts at a temperature 130K higher than in free ice, and relatively thick ice films ( 2.6nm at 298K and 2.2nm at 310K ) are stabilized by dipole interactions with the substrate. This unique physical effect may enable biocompatibility-enhancing ice overcoatings for diamond at human body temperature.

  2. Diamond-like carbon coatings for orthopaedic applications: an evaluation of tribological performance.

    PubMed

    Xu, T; Pruitt, L

    1999-02-01

    A detailed investigation of the tribological behaviour of vacuum arc diamond-like carbon coated Ti-6Al-4V against a medical grade ultra-high molecular weight polyethylene is conducted in this work in order to investigate the potential use of diamond-like carbon coatings for orthopaedic appplications. Lubricated and non-lubricated wear experiments are performed using a standard pin-on-disc wear tester. The coefficient of friction is monitored continuously during testing and wear rate calculations are performed using surface profilometry measurements of worn disc surfaces. Sliding wear tests show the existence of two distinct friction and wear regimes distinguished by physically different mechanisms. In the first stages of wear, adhesion and abrasion are the dominant mechanisms of wear while fatigue processes are activated later in the tests. The effects of diamond-like carbon coating structure, surface roughness and lubrication on tribological behaviour are presented. Optimal process-structure-property design for vacuum arc plasma deposition is utilized in order to obtain strong adhesion to the titanium alloy substrate. Diamond-like carbon coatings significantly improve the friction and wear performance of the orthopaedic bearing pair and show exceptional promise for biomedical applications. PMID:15347929

  3. 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.

  4. 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.

  5. Characterization and measurement of polymer wear

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  6. Computer controlled precision optical polishing on the diamond turning machine

    SciTech Connect

    Hannah, P.R.; Day, R.D.; Hatch, D.

    1993-10-01

    This abstract reports the force and wear data required to predict the material removal, or wear, for the Numerical controlled (N/C) polishing program. The program`s aim is to provide the operator of a N/C diamond turning machine or N/C grinding machine with the wear characteristics necessary to achieve uniform material removal. The first phase of the program looks at a rotating polishing wheel, moving from near the center to edge of a rotating glass disc. future phases will look at more complex shapes.

  7. The current understanding on the diamond machining of silicon carbide

    NASA Astrophysics Data System (ADS)

    Goel, Saurav

    2014-06-01

    The Glenn Research Centre of NASA, USA (www.grc.nasa.gov/WWW/SiC/, silicon carbide electronics) is in pursuit of realizing bulk manufacturing of silicon carbide (SiC), specifically by mechanical means. Single point diamond turning (SPDT) technology which employs diamond (the hardest naturally-occurring material realized to date) as a cutting tool to cut a workpiece is a highly productive manufacturing process. However, machining SiC using SPDT is a complex process and, while several experimental and analytical studies presented to date aid in the understanding of several critical processes of machining SiC, the current knowledge on the ductile behaviour of SiC is still sparse. This is due to a number of simultaneously occurring physical phenomena that may take place on multiple length and time scales. For example, nucleation of dislocation can take place at small inclusions that are of a few atoms in size and once nucleated, the interaction of these nucleations can manifest stresses on the micrometre length scales. The understanding of how these stresses manifest during fracture in the brittle range, or dislocations/phase transformations in the ductile range, is crucial to understanding the brittle-ductile transition in SiC. Furthermore, there is a need to incorporate an appropriate simulation-based approach in the manufacturing research on SiC, owing primarily to the number of uncertainties in the current experimental research that includes wear of the cutting tool, poor controllability of the nano-regime machining scale (effective thickness of cut), and coolant effects (interfacial phenomena between the tool, workpiece/chip and coolant), etc. In this review, these two problems are combined together to posit an improved understanding on the current theoretical knowledge on the SPDT of SiC obtained from molecular dynamics simulation.

  8. Wear Resistance of Coating Films on Hob Teeth

    NASA Astrophysics Data System (ADS)

    Umezaki, Yoji; Funaki, Yoshiyuki; Kurokawa, Syuhei; Ohnishi, Osamu; Doi, Toshiro

    The wear resistance of coating films on hob teeth is investigated through the simulated hobbing tests with a flytool. The coating films on hob teeth are titanium family ceramics such as TiN, TiCN, TiSiN and TiAlN and aluminum chromium family ceramics such as AlCrN and AlCrSiN. The wear of coated tools is shown about film thickness, film materials, ingredient ratio in a film component and the oxidization of coating films. The oxidization is clarified from a result of the influence on the crater wear progress through wear cutting tests in atmosphere of nitrogen gas or oxygen gas. The oxidization of TiAlN coating films produces oxide products on the tool rake face, and this oxidation relates to the amount of crater wear. The increase of aluminum concentration in the TiAlN film improves the crater wear resistance in air atmosphere, while it has a reverse effect in nitrogen gases. The AlCrSiN film has effective wear resistance against the abrasive wear and/or oxidization wear. The oxidation film formed on the AlCrSiN film is very firm and this suppresses the oxidation wear on the rake face and works against the abrasive wear advantageously.

  9. 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. PMID:27160557

  10. 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.

  11. 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

  12. The mechanical and strength properties of diamond

    NASA Astrophysics Data System (ADS)

    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 materials

  13. Diagnosis of erosive tooth wear.

    PubMed

    Ganss, Carolina; Lussi, Adrian

    2014-01-01

    The clinical diagnosis 'erosion' is made from characteristic deviations from the original anatomical tooth morphology, thus distinguishing acid-induced tissue loss from other forms of wear. Primary pathognomonic features are shallow concavities on smooth surfaces occurring coronal from the enamel-cementum junction. Problems from diagnosing occlusal surfaces and exposed dentine are discussed. Indices for recording erosive wear include morphological as well as quantitative criteria. Currently, various indices are used, each having their virtues and flaws, making the comparison of prevalence studies difficult. The Basic Erosive Wear Examination (BEWE) is described, which is intended to provide an easy tool for research as well as for use in general dental practice. The cumulative score of this index is the sum of the most severe scores obtained from all sextants and is linked to suggestions for clinical management. In addition to recording erosive lesions, the assessment of progression is important as the indication of treatment measures depends on erosion activity. A number of evaluated and sensitive methods for in vitro and in situ approaches are available, but the fundamental problem for their clinical use is the lack of reidentifiable reference areas. Tools for clinical monitoring are described. PMID:24993255

  14. 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.

  15. Influence of coolant on ductile mode processing of binderless nanocrystalline tungsten carbide through ultraprecision diamond turning

    NASA Astrophysics Data System (ADS)

    Doetz, Marius; Dambon, Olaf; Klocke, Fritz; Fähnle, Oliver

    2015-08-01

    Molds made of tungsten carbide are typically used for the replicative mass production of glass lenses by precision glass molding. Consequently an ultra-precision grinding process with a subsequent fresh-feed polishing operation is conventionally applied. These processes are time consuming and have a relatively low reproducibility. An alternative manufacturing technology, with a high predictability and efficiency, which additionally allows a higher geometrical flexibility, is the single point diamond turning technique (SPDT). However, the extreme hardness and the chemical properties of tungsten carbide lead to significant tool wear and therefore the impossibility of machining the work pieces in an economical way. One approach to enlarge the tool life is to affect the contact zone between tool and work piece by the use of special cutting fluids. This publication emphasizes on the most recent investigations and results in direct machining of nano-grained tungsten carbide with mono crystal diamonds under the influence of various kinds of cutting fluids. Therefore basic ruling experiments on binderless nano grained tungsten carbide were performed, where the tool performed a linear movement with a steadily increasing depth of cut. As the ductile cutting mechanism is a prerequisite for the optical manufacturing of tungsten carbide these experiments serve the purpose for establish the influence of different cutting fluid characteristics on the cutting performance of mono crystal diamonds. Eventually it is shown that by adjusting the coolant fluid it is possible to significantly shift the transition point from ductile to brittle removal to larger depths of cut eventually enabling a SPDT of binderless tungsten carbide molds.

  16. 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.

  17. 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. PMID:24953823

  18. Deposition Of Cubic BN On Diamond Interlayers

    NASA Technical Reports Server (NTRS)

    Ong, Tiong P.; Shing, Yuh-Han

    1994-01-01

    Thin films of polycrystalline, pure, cubic boron nitride (c-BN) formed on various substrates, according to proposal, by chemical vapor deposition onto interlayers of polycrystalline diamond. Substrate materials include metals, semiconductors, and insulators. Typical substrates include metal-cutting tools: polycrystalline c-BN coats advantageous for cutting ferrous materials and for use in highly oxidizing environments-applications in which diamond coats tend to dissolve in iron or be oxidized, respectively.

  19. 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

  20. 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.

  1. 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.

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

    DOE PAGESBeta

    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

  3. Synthesis and Characterization of Multilayered Diamond Coatings for Biomedical Implants

    PubMed Central

    Booth, Leigh; Catledge, Shane A.; Nolen, Dustin; Thompson, Raymond G.; Vohra, Yogesh K.

    2011-01-01

    With incredible hardness and excellent wear-resistance, nanocrystalline diamond (NCD) coatings are gaining interest in the biomedical community as articulating surfaces of structural implant devices. The focus of this study was to deposit multilayered diamond coatings of alternating NCD and microcrystalline diamond (MCD) layers on Ti-6Al-4V alloy surfaces using microwave plasma chemical vapor deposition (MPCVD) and validate the multilayer coating’s effect on toughness and adhesion. Multilayer samples were designed with varying NCD to MCD thickness ratios and layer numbers. The surface morphology and structural characteristics of the coatings were studied with X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM). Coating adhesion was assessed by Rockwell indentation and progressive load scratch adhesion tests. Multilayered coatings shown to exhibit the greatest adhesion, comparable to single-layered NCD coatings, were the multilayer samples having the lowest average grain sizes and the highest titanium carbide to diamond ratios. PMID:21603588

  4. 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.

  5. Factors Governing Surface Form Accuracy In Diamond Machined Components

    NASA Astrophysics Data System (ADS)

    Myler, J. K.; Page, D. A.

    1988-10-01

    Manufacturing methods for diamond machined optical surfaces, for application at infrared wavelengths, require that a new set of criteria must be recognised for the specification of surface form. Appropriate surface form parameters are discussed with particular reference to an XY cartesian geometry CNC machine. Methods for reducing surface form errors in diamond machining are discussed for certain areas such as tool wear, tool centring, and the fixturing of the workpiece. Examples of achievable surface form accuracy are presented. Traditionally, optical surfaces have been produced by use of random polishing techniques using polishing compounds and lapping tools. For lens manufacture, the simplest surface which could be created corresponded to a sphere. The sphere is a natural outcome of a random grinding and polishing process. The measurement of the surface form accuracy would most commonly be performed using a contact test gauge plate, polished to a sphere of known radius of curvature. QA would simply be achieved using a diffuse monochromatic source and looking for residual deviations between the polished surface and the test plate. The specifications governing the manufacture of surfaces using these techniques would call for the accuracy to which the generated surface should match the test plate as defined by a spherical deviations from the required curvature and a non spherical astigmatic error. Consequently, optical design software has tolerancing routines which specifically allow the designer to assess the influence of spherical error and astigmatic error on the optical performance. The creation of general aspheric surfaces is not so straightforward using conventional polishing techniques since the surface profile is non spherical and a good approximation to a power series. For infra red applications (X = 8-12p,m) numerically controlled single point diamond turning is an alternative manufacturing technology capable of creating aspheric profiles as well as

  6. '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.

  7. '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.

  8. '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.

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Tribological evaluation of diamond coating on pure titanium in comparison with plasma nitrided titanium and uncoated titanium

    SciTech Connect

    Yan, B.; Loh, N.L.; Fu, Y.; Sun, C.Q.; Hing, P.

    1999-12-01

    Titanium alloys are characterized by poor tribological properties, and the traditional use of titanium alloys has been restricted to nontribological applications. The deposition of a well adherent diamond coating is a promising way to solve this problem. In this study, the tribological properties of diamond-coated titanium were studied using a pin-on-disk tribometer, and the results were compared with those of pure titanium and plasma nitrided titanium. The tribological behavior of pure titanium was characterized by high coefficient of friction and rapid wear of materials. Plasma nitriding improved the wear resistance only under low normal load; however, this hardened layer was not efficient in improving the wear resistance and the friction properties under high normal load. Diamond coating on pure titanium improved the wear resistance of titanium significantly. Surface profilometry measurement indicated that little or no wear of the diamond coating occurred under the test conditions loads. The roughness of the diamond coating was critical because it controlled the amount of abrasive damage on the counterface. Reducing the surface roughness by polishing led to the reductions in both the friction and wear of the counterface.

  18. 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

  19. 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.

  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. Theory of powdery rubber wear

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2009-12-01

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear.

  2. 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.

  3. 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.

  4. 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.

  5. Tribological performance of diamond and diamondlike carbon films at elevated temperatures

    SciTech Connect

    Erdemir, A.; Fenske, G.R.

    1995-09-01

    In this study, we investigated the tribological performance of diamond and diamondlike carbon (DLC) films as a function of ambient temperature. Both films were deposited on silicon carbide (SiC) by microwave plasma chemical vapor deposition and ion-beam deposition processes. Tribological tests were performed on a reciprocating wear machine in open air (20 to 30% relative humidity) and under a 10-N load using SiC pins. For the test conditions explored, the steady- state friction coefficients of test pairs without a diamond or DLC film were 0.7 to 0.9 and the average wear rates of pins were 10{sup {minus}5} to 10{sup {minus}7} mm{sup 3}/N.m, depending on ambient temperature. DLC films reduced the steady-state friction coefficients of test pairs by factors of 3 to 5 and the wear rates of pins by two to three orders of magnitude. Low friction coefficients were also obtained with the diamond films, but wear rates of the counterface pins were high due to the very abrasive nature of these films. The wear of SiC disks coated with either diamond or DLC films was virtually unmeasurable while the wear of uncoated disks was substantial. Test results showed that the DLC films could afford low friction up to about 300{degrees}C. At higher temperatures, the DLC films became graphitized and were removed from the surface. The diamond films could withstand much higher temperatures, but their tribological behavior degraded. Raman spectroscopy and scanning electron microscopy were used to elucidate the friction and wear mechanisms of both films at high temperatures.

  6. 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).

  7. 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).

  8. Wellhead bowl protector and retrieving tool

    SciTech Connect

    Young, J.A.

    1991-09-03

    This patent describes improvement in a wellhead protection system including a wear bushing and a retrieving tool. The improvement comprises a wear bushing supported within the wellhead, wherein the wear bushing includes an enlarged upper end having an external support shoulder for engagement with an internal support shoulder formed in the wellhead; wherein the wear bushing further includes an internal circumferential slot intersected by at least one vertically extending slot, the vertical slot extending from the circumferential slot to the upper end of the wear bushing; a retrieving tool having at least one outwardly biased, retractable lug member mounted thereon; and wherein the retrieving tool includes an enlarged portion adapted to be received within the enlarged upper end of the wear bushing. This patent also describes a method of retrieving a wear bushing from a wellhead comprising the steps of: lowering a retrieving tool into the wellhead for locking engagement with the wear bushing; aligning the retrieving tool with the wear bushing for automatically forcing lug members carried by the retrieving tool outwardly into locking engagement with the wear bushing; monitoring drill string weight for determining engagement of the retrieving tool with the wear bushing, wherein a substantial decrease in drill string weight is an indication that the retrieving tool is engaged with the wear bushing; and removing the wear bushing from the wellhead.

  9. Ion implantation to reduce wear on polyethylene prosthetic devices. Rept. for Aug 89-Jan 91

    SciTech Connect

    Not Available

    1991-05-01

    Researchers studied the use of ion implantation to improve the wear performance of ultra high molecular weight polyethylene (UHMWPE). UHMWPE samples were implanted with high energy ions, tested for wear performance, and compared to unimplanted control samples. Surface friction and hardness measurements, Raman scattering, Rutherford backscattering (RBS), water contact angle, and film transfer tests were performed to characterize the surface property changes of implanted UHMWPE samples. Results indicated a 90% reduction in wear on implanted UHMWPE disks. Implantation increased surface microhardness and surface energy. The Raman spectrum revealed a diamond-like signature, indicting carbon bonds of a different nature than those found in unimplanted polyehtylene. Photographic analysis of pins used in wear testing revealed differences between implanted and unimplanted samples in the polyethylene film transferred in the initial stages of wear from the disk to the pin.

  10. 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

  11. Wear Independent Similarity.

    PubMed

    Steele, Adam; Davis, Alexander; Kim, Joohyung; Loth, Eric; Bayer, Ilker S

    2015-06-17

    This study presents a new factor that can be used to design materials where desired surface properties must be retained under in-system wear and abrasion. To demonstrate this factor, a synthetic nonwetting coating is presented that retains chemical and geometric performance as material is removed under multiple wear conditions: a coarse vitrified abradant (similar to sanding), a smooth abradant (similar to rubbing), and a mild abradant (a blend of sanding and rubbing). With this approach, such a nonwetting material displays unprecedented mechanical durability while maintaining desired performance under a range of demanding conditions. This performance, herein termed wear independent similarity performance (WISP), is critical because multiple mechanisms and/or modes of wear can be expected to occur in many typical applications, e.g., combinations of abrasion, rubbing, contact fatigue, weathering, particle impact, etc. Furthermore, these multiple wear mechanisms tend to quickly degrade a novel surface's unique performance, and thus many promising surfaces and materials never scale out of research laboratories. Dynamic goniometry and scanning electron microscopy results presented herein provide insight into these underlying mechanisms, which may also be applied to other coatings and materials. PMID:26018058

  12. P/M Materials for Wear Applications

    SciTech Connect

    Hawk, Jeffrey A.

    2000-10-01

    Wear resistant materials usually consist of either very hard homogeneous single phase materials (e.g., ceramics like Al2O3, SiC, etc.) or heterogenous materials (e.g., white cast irons, composites or cermets, or composite-type materials), typically with a hard reinforcing phase dispersed in a softer matrix. In both instances, the result is the same, less penetration of the abrasive into the surface of the material being worn. Composite type materials can be produced using either a melting/solidification scheme or through powder metallurgy (P/M) techniques. In either case the result is the same, a microstructure that consists of a high volume fraction of hard, usually brittle, second phase particles in a softer matrix. However, P/M can be used to create a wider range of these materials than can melting/solidification, because in P/M processing, the desired phase does not have to be precipitated during solidification. Thus, more materials can be produced with higher volume fractions of reinforcing phases. Obviously, other factors like reinforcement size, matrix-particle interfacial strength, plastic accommodation of the matrix, etc. become important in the wear behavior of these materials. Various categories of P/M wear resistant materials will be discussed, and their wear behavior will be compared against traditional wear resistant cast materials like white cast iron and tool steels.

  13. An in vitro investigation of wear resistance and hardness of composite resins

    PubMed Central

    Cao, Liqun; Zhao, Xinyi; Gong, Xu; Zhao, Shouliang

    2013-01-01

    Purpose: The aim of the present study was to investigate the wear resistance and hardness of five kinds of composite resins. Materials and Methods: Sixty-five specimens were fabricated with one nano-hybrid (Charisma Diamond), two micro-hybrid (3MZ250, Clearfil AP-X) and two packable (3MP60, Surefil) composite resins, according to a randomized complete block design (n=13, 8 for wear test; 5 for hardness test). The composites were filled in a rectangular mold, and light polymerization. After storage in 37°C deionized water for 24h, all specimens were tested with a custom-made toothbrush machine with a stainless-steel ball as antagonist (3N loads, 1Hz, 6×105 cycles) immersed in calcium fluoride slurry. Wear volume, hardness and surface structure of each tested material was examined by a three-dimensional non-contact optical profilometer, Vickers indentation technique and scanning electron microscope. Results: The volume loss ranked from least to most as follows: Charisma Diamond, P60, Z250, Clearfil AP-X and Surefil. Regarding hardness, the rank from highest to lowest as follows: Clearfil AP-X, P60, Surefil, Z250, Charisma Diamond. The interactions between wear resistance and microhardness were not significant. Conclusions: The custom-made machine is considered suitable to simulate sliding of an antagonist cusp on an opposing occlusal composite restoration. Nanofilled composite may have superior wear compared to other composite resins. PMID:23844265

  14. Optical wear monitoring

    DOEpatents

    Kidane, Getnet S; Desilva, Upul P.; He, Chengli; Ulerich, Nancy H.

    2016-07-26

    A gas turbine includes first and second parts having outer surfaces located adjacent to each other to create an interface where wear occurs. A wear probe is provided for monitoring wear of the outer surface of the first part, and includes an optical guide having first and second ends, wherein the first end is configured to be located flush with the outer surface of the first part. A fiber bundle includes first and second ends, the first end being located proximate to the second end of the optical guide. The fiber bundle includes a transmit fiber bundle comprising a first plurality of optical fibers coupled to a light source, and a receive fiber bundle coupled to a light detector and configured to detect reflected light. A processor is configured to determine a length of the optical guide based on the detected reflected light.

  15. 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.

  16. 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.

  17. Tribochemistry of Carbon Films in Oxygen and Humid Environments: Oxidative Wear and Galvanic Corrosion.

    PubMed

    Alazizi, Ala; Draskovics, Andrew; Ramirez, Giovanni; Erdemir, Ali; Kim, Seong H

    2016-03-01

    The effects of oxidation on wear of carbon/steel tribological interfaces were studied. When mechanical wear was small, the oxidation behavior of hydrogenated diamond-like carbon (H-DLC) and stainless steel (SS) sliding interface varied depending on the nature of the oxidizing environment. In dry air or oxygen, both H-DLC and SS wore readily. The wear debris of SS did not form iron oxide in dry air and oxygen. In humid nitrogen, however, the wear of H-DLC diminished with increasing humidity, and the SS surface showed mild wear and iron oxide debris accumulated around the sliding contact region. These results revealed that different tribochemical reactions occur in dry oxygen and humid environments. In the absence of water, oxygen oxidizes the H-DLC surface, making it susceptible to wear, creating debris, and inducing wear on both H-DLC and SS. In contrast, adsorbed water molecules at less than 40% RH act as a molecular lubricant of the oxidized DLC surface, while multiwater layers adsorbed at near-saturation act as electrolyte inducing electrochemical galvanic corrosion reactions on the SS surface. When hydrogen-free amorphous carbon (a-C) was used in tribo-tests, severe wear of the SS surface occurs, in addition to the tribochemical wear observed for H-DLC, due to the high hardness of the a-C film. PMID:26844949

  18. Registration of 3-D holograms of diamond crystals (Abstract Only)

    NASA Astrophysics Data System (ADS)

    Marchenko, S. N.; Smirnova, S. N.

    1991-02-01

    Registration of 3D ho1orarns broadens the possibility of using single-crystal tool for imagining and investigating inner inhomogeneities and dynamic stresses in top area of gem diamond, study of which by other techniques,e.g. polarization optics, is difficult or impossible. The difficulty is that the diamond with significant refractive index of 2.42 has comparatively small angle of total internal reflection of 24°50. As a result, with random illumination of the tops of octahedron diamond crystals, both smooth- faceted and with polycentric facets, illuminating light is successively reflected from different farets and absorbed in the crystal or comes out of it in a spot and direction that are difficult to calculate. Optimal schemes of illuminating crystals for recording 3D holograms of smooth faceted octahedron diamonds are given. Analysis of illumination of the crystal with polycentric facets shows that correction of light in the diamond is determined by directivity diagram the width of which depends in inhomogeneity size of the diamond. 3D holograms of diamonds with different reflectivity were produced. For the first time the possibility is shown for registration of holograms for studying stresses in diamond top using single-crystal tool.

  19. 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.

  20. 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.

  1. 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.

  2. 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…

  3. Wear resistant valve

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor)

    1980-01-01

    A valve which is resistant to wear caused by particles trapped between the valve seat and the valve member or poppet when the valve closes, including an outlet for directing washing fluid at the valve seat and/or sealing face of the poppet and means for supplying pressured fluid to the outlet at the time when the valve is closing.

  4. Localized and generalized simulated wear of resin composites.

    PubMed

    Barkmeier, W W; Takamizawa, T; Erickson, R L; Tsujimoto, A; Latta, M; Miyazaki, M

    2015-01-01

    A laboratory study was conducted to examine the wear of resin composite materials using both a localized and generalized wear simulation model. Twenty specimens each of seven resin composites (Esthet•X HD [HD], Filtek Supreme Ultra [SU], Herculite Ultra [HU], SonicFill [SF], Tetric EvoCeram Bulk Fill [TB], Venus Diamond [VD], and Z100 Restorative [Z]) were subjected to a wear challenge of 400,000 cycles for both localized and generalized wear in a Leinfelder-Suzuki wear simulator (Alabama machine). The materials were placed in custom cylinder-shaped stainless steel fixtures. A stainless steel ball bearing (r=2.387 mm) was used as the antagonist for localized wear, and a stainless steel, cylindrical antagonist with a flat tip was used for generalized wear. A water slurry of polymethylmethacrylate (PMMA) beads was used as the abrasive media. A noncontact profilometer (Proscan 2100) with Proscan software was used to digitize the surface contours of the pretest and posttest specimens. AnSur 3D software was used for wear assessment. For localized testing, maximum facet depth (μm) and volume loss (mm(3)) were used to compare the materials. The mean depth of the facet surface (μm) and volume loss (mm(3)) were used for comparison of the generalized wear specimens. A one-way analysis of variance (ANOVA) and Tukey post hoc test were used for data analysis of volume loss for both localized and generalized wear, maximum facet depth for localized wear, and mean depth of the facet for generalized wear. The results for localized wear simulation were as follows [mean (standard deviation)]: maximum facet depth (μm)--Z, 59.5 (14.7); HU, 99.3 (16.3); SU, 102.8 (13.8); HD, 110.2 (13.3); VD, 114.0 (10.3); TB, 125.5 (12.1); SF, 195.9 (16.9); volume loss (mm(3))--Z, 0.013 (0.002); SU, 0.026 (0.006); HU, 0.043 (0.008); VD, 0.057 (0.009); HD, 0.058 (0.014); TB, 0.061 (0.010); SF, 0.135 (0.024). Generalized wear simulation results were as follows: mean depth of facet (μm)--Z, 9.3 (3

  5. 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.

  6. 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

  7. 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. PMID:24922087

  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. Plasma and ion beam enhanced chemical vapour deposition of diamond and diamond-like carbon

    NASA Astrophysics Data System (ADS)

    Tang, Yongji

    WC-Co cutting tools are widely used in the machining industry. The application of diamond coatings on the surfaces of the tools would prolong the cutting lifetime and improves the manufacturing efficiency. However, direct chemical vapor deposition (CVD) of diamond coatings on WC-Co suffer from severe premature adhesion failure due to interfacial graphitization induced by the binder phase Co. In this research, a combination of hydrochloric acid (HCl) and hydrogen (H2) plasma pretreatments and a novel double interlayer of carbide forming element (CFE)/Al were developed to enhance diamond nucleation and adhesion. The results showed that both the pretreatments and interlayers were effective in forming continuous and adhesive nanocrystalline diamond coatings. The method is a promising replacement of the hazardous Murakami's regent currently used in WC-Co pretreatment with a more environmental friendly approach. Apart from coatings, diamond can be fabricated into other forms of nanostructures, such as nanotips. In this work, it was demonstrated that oriented diamond nanotip arrays can be fabricated by ion beam etching of as-grown CVD diamond. The orientation of diamond nanotips can be controlled by adjusting the direction of incident ion beam. This method overcomes the limits of other techniques in producing nanotip arrays on large areas with controlled orientation. Oriented diamond nano-tip arrays have been used to produce anisotropic frictional surface, which is successfully used in ultra-precision positioning systems. Diamond-like carbon (DLC) has many properties comparable to diamond. In this thesis, the preparation of alpha-C:H thin films by end-Hall (EH) ion source and the effects of ion energy and nitrogen doping on the microstructure and mechanical properties of the as-deposited thin films were investigated. The results have demonstrated that smooth and uniform alpha-C:H and alpha-C:H:N films with large area and reasonably high hardness and Young's modulus can be

  10. 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.

  11. 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

  12. Diamond Turning Of Infra-Red Components

    NASA Astrophysics Data System (ADS)

    Hodgson, B.; Lettington, A. H.; Stillwell, P. F. T. C.

    1986-05-01

    Single point diamond machining of infra-red optical components such as aluminium mirrors, germanium lenses and zinc sulphide domes is potentially the most cost effective method for their manufacture since components may be machined from the blanks to a high surface finish, requiring no subsequent polishing, in a few minutes. Machines for the production of flat surfaces are well established. Diamond turning lathes for curved surfaces however require a high capital investment which can be justified only for research purposes or high volume production. The present paper describes the development of a low cost production machine based on a Bryant Symons diamond turning lathe which is able to machine spherical components to the required form and finish. It employs two horizontal spindles one for the workpiece the other for the tool. The machined radius of curvature is set by the alignment of the axes and the radius of the tool motion, as in conventional generation. The diamond tool is always normal to the workpiece and does not need to be accurately profiled. There are two variants of this basic machine. For machining hemispherical domes the axes are at right angles while for lenses with positive or negative curvature these axes are adjustable. An aspherical machine is under development, based on the all mechanical spherical machine, but in which a ± 2 mm aspherecity may be imposed on the best fit sphere by moving the work spindle under numerical control.

  13. Theory of powdery rubber wear.

    PubMed

    Persson, B N J

    2009-12-01

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear. PMID:21832508

  14. Limiting dogleg is a key to reducing casing wear

    SciTech Connect

    Bettis, F.E.; Schwanitz, B.J. ); Crane, L. )

    1994-08-01

    A field study, involving logging runs with an ultrasonic imaging tool, of several wells drilled in Alaska indicates causing wear from drill pipe rotation can be reduced if the dogleg severity is kept less than 5[degree]/1,000 ft. Factors related to casing pipe wear include drill pipe hardbanding, hole deviation, and directional dogleg severity. Excessively worn casing may not withstand pressure tests, may develop holes, or may cause operational problems. The Ultra Sonic Imaging (USI) tool measures the extent of casing wear from normal drillstring rotation. USI logs are run to evaluate cement and measure casing thickness (results are presented in terms of metal loss). Field examples clearly illustrate the strong correlation between increased dog-leg severity and increased casing wear.

  15. 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.

  16. 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. PMID:27004415

  17. 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

  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. 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.

  20. 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.

  1. 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

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

    SciTech Connect

    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.

  3. Effect of microstructure on sliding contact damage and wear of ceramic coatings.

    SciTech Connect

    Ajayi, O. O.; Shareef, I.; Fenske, G. R.; Energy Technology; Bradley Univ.

    2006-01-01

    Hard and wear resistant ceramics coatings are often applied to metallic surfaces to enhance their tribological performance. Using the scratch and twin roller tests, we evaluated the surface contact damage and the mechanism of wear in different ceramic coating. In amorphous diamond-like carbon coating, the damage and eventual material removal occurred by straight cracking that follows the trajectory of the tensile stresses. Damage in a crystalline titanium nitride (TiN) coating with a columnar grain structure occurred primarily by inter-columnar cracking perpendicular to the surface. For crystalline chromium nitride (CrN) coating with equiaxed grains, contact damage consisted primarily of grain boundary cracking and wear is due to surface-layer grain pullout. Results of the present study showed the dominant effect of ceramic coating microstructure on the contact damage and wear mechanism.

  4. 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

  5. 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)

  6. 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.

  7. 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.

  8. Diamond nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Taniguchi, Jun; Tokano, Yuji; Miyamoto, Iwao; Komuro, Masanori; Hiroshima, Hiroshi

    2002-10-01

    Electron beam (EB) lithography using polymethylmethacrylate (PMMA) and oxygen gas reactive ion etching (RIE) were used to fabricate fine patterns in a diamond mould. To prevent charge-up during EB lithography, thin conductive polymer was spin-coated over the PMMA resist, yielding dented line patterns 2 μ m wide and 270 nm deep. The diamond mould was pressed into PMMA on a silicon substrate heated to 130, 150 and 170ºC at 43.6, 65.4 and 87.2 MPa. All transferred PMMA convex line patterns were 2 μ m wide. Imprinted pattern depth increased with rising temperature and pressure. PMMA patterns on diamond were transferred by the diamond mould at 150ºC and 65.4 MPa, yielding convex line patterns 2 μ m wide and 200 nm high. Direct aluminium and copper patterns were obtained using the diamond mould at room temperature and 130.8 MPa. The diamond mould is thus useful for replicating patterns on PMMA and metals.

  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. 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. PMID:26924136

  11. 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.

  12. 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

  13. Wear Performance of Saw Blades in Processing of Granitic Rocks and Development of Models for Wear Estimation

    NASA Astrophysics Data System (ADS)

    Aydin, Gokhan; Karakurt, Izzet; Aydiner, Kerim

    2013-11-01

    This study investigates the wear performance of diamond circular saw blades in cutting of granitic rocks. An alternative wear measuring method is developed to measure the reduced blade radius without taking the blade off the machine. The effect on and contribution to the specific wear rate (SWR) of each operating variable are determined, and the SWR is correlated with rock properties. Morphologies of wearing surfaces of segments and rocks are also evaluated using scanning electron microscopy (SEM). Depending on both operating variables and rock properties, prediction models are developed for estimation of the SWR. Results show that the SWR increases with an increase in the peripheral speed and the traverse speed, while it decreases with an increase in the cutting depth and the flow rate of the cooling fluid. The peripheral speed, and the microhardness and proportions of minerals such as quartz, plagioclase, and feldspar are statistically determined as the significant variables affecting the SWR. Finally, it is disclosed that models developed for estimation of SWR have great potential for practical applications.

  14. Wear Characteristics of Sintered Cermets

    NASA Astrophysics Data System (ADS)

    Bidulský, Róbert; Bidulská, Jana; Arenas, Freddy; Grande, Marco Actis

    2012-02-01

    The present paper deals with the tribological behaviour of the boride and carbide hardmetals evaluated by performing comparative dry sliding pin-on-disc experiments using normal contact loads. Analyses of the wear performance results, microstructural evaluation and processing conditions effect indicate that microstructure inhomogenities play an important role in abrasive wear behaviour of cermets. In term of grain size and chemical composition, the addition of VC also play an important role in increasing the wear resistance.

  15. Mechanical modelling of tooth wear.

    PubMed

    Karme, Aleksis; Rannikko, Janina; Kallonen, Aki; Clauss, Marcus; Fortelius, Mikael

    2016-07-01

    Different diets wear teeth in different ways and generate distinguishable wear and microwear patterns that have long been the basis of palaeodiet reconstructions. Little experimental research has been performed to study them together. Here, we show that an artificial mechanical masticator, a chewing machine, occluding real horse teeth in continuous simulated chewing (of 100 000 chewing cycles) is capable of replicating microscopic wear features and gross wear on teeth that resemble wear in specimens collected from nature. Simulating pure attrition (chewing without food) and four plant material diets of different abrasives content (at n = 5 tooth pairs per group), we detected differences in microscopic wear features by stereomicroscopy of the chewing surface in the number and quality of pits and scratches that were not always as expected. Using computed tomography scanning in one tooth per diet, absolute wear was quantified as the mean height change after the simulated chewing. Absolute wear increased with diet abrasiveness, originating from phytoliths and grit. In combination, our findings highlight that differences in actual dental tissue loss can occur at similar microwear patterns, cautioning against a direct transformation of microwear results into predictions about diet or tooth wear rate. PMID:27411727

  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. 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.

  18. 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.

  19. Diamond Electronic Devices

    SciTech Connect

    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 deg.n 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 ({approx}1 nm) doped layers in order to achieve high RT activation.

  20. 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.

  1. Diamond turning microstructure optical components

    NASA Astrophysics Data System (ADS)

    Jiang, Wenda

    2009-05-01

    Microstructure optical components in the form of Fresnel, TIR, microgroove, micro lens array provide a lot design freedom for high compact optical systems. It is a key factor which enables the cutting edge technology for telecommunication, surveillance and high-definition display system. Therefore, the demand of manufacturing such element is rapidly increasing. These elements usually contain high precision, tiny structure and complex form, which have posed many new challenges for tooling, programming as well as ultra-precision machining. To cope with the fast development of the technology and meet the increasing demand of the market, we have developed our own manufacturing process to fabricate microstructure optical components by way of Diamond tuning, Shaping, Raster cutting, Slow Slide Servo (SSS), Diamond milling and Post polishing. This paper is to focus on how we employed these methods to produce complex prototype of microstructure optical components and precision mold inserts which either contains aspheric lens array or freeform V grooves. The high quality finish of these surfaces meets application requirements. Measurement results are presented. Advantages and disadvantages of these methods are compared and discussed in the paper.

  2. 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

  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. 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.

  5. 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)

  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. Human monocytes stimulation by particles of hydroxyapatite, silicon carbide and diamond: in vitro studies of new prosthesis coatings.

    PubMed

    Nordsletten, L; Høgåsen, A K; Konttinen, Y T; Santavirta, S; Aspenberg, P; Aasen, A O

    1996-08-01

    Aseptic loosening due to wear and debris formation constitutes the major problem in longevity of joint replacements. Diamond coated onto the prosthesis surface may reduce wear, owing to its excellent tribological properties. A thin diamond coating may be brittle, and we plan eventually to reinforce it with silicon carbide whiskers (SiC). In the present study we compared particles of diamond, SiC and hydroxyapatite (HA) in serum-free cultures of human monocytes. All particles were found to be phagocytozed, and monocyte morphology changed except after the ingestion of diamond. Interleukin-1 beta production was increased on average 30-fold and 38-fold in cultures exposed to HA and SiC, respectively, compared to control and diamond cultures (n = 6). Addition of the phagocytosis inhibitor cytochalasin B inhibited the morphological changes of the monocytes and reduced interleukin-1 beta production. In some experiments particles of polymethylmethacrylate were also included, and the interleukin-1 beta stimulation was in the same range as after HA and SiC stimulation. The results show that diamond particles in serum-free monocyte culture are inert, while SiC and HA have a stimulatory effect comparable to polymethylmethacrylate. With its excellent tribological and biocompatible properties, future studies with diamond coating are warranted. PMID:8853123

  8. 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.)

  9. Erosive tooth wear in children.

    PubMed

    Carvalho, Thiago S; Lussi, Adrian; Jaeggi, Thomas; Gambon, Dein L

    2014-01-01

    Erosive tooth wear in children is a common condition. Besides the anatomical differences between deciduous and permanent teeth, additional histological differences may influence their susceptibility to dissolution. Considering laboratory studies alone, it is not clear whether deciduous teeth are more liable to erosive wear than permanent teeth. However, results from epidemiological studies imply that the primary dentition is less wear resistant than permanent teeth, possibly due to the overlapping of erosion with mechanical forces (like attrition or abrasion). Although low severity of tooth wear in children does not cause a significant impact on their quality of life, early erosive damage to their permanent teeth may compromise their dentition for their entire lifetime and require extensive restorative procedures. Therefore, early diagnosis of erosive wear and adequate preventive measures are important. Knowledge on the aetiological factors of erosive wear is a prerequisite for preventive strategies. Like in adults, extrinsic and intrinsic factors, or a combination of them, are possible reasons for erosive tooth wear in children and adolescents. Several factors directly related to erosive tooth wear in children are presently discussed, such as socio-economic aspects, gastroesophageal reflux or vomiting, and intake of some medicaments, as well as behavioural factors such as unusual eating and drinking habits. Additionally, frequent and excessive consumption of erosive foodstuffs and drinks are of importance. PMID:24993274

  10. Processing of functionally graded tungsten carbide-cobalt-diamond composites

    NASA Astrophysics Data System (ADS)

    Jain, Mohit

    Polycrystalline diamond compacts (PDCs) are widely used as drill bit cutters in rock drilling and as tool bits in machining non-ferrous materials. A typical PDC comprises a thin layer of sintered polycrystalline diamond bonded to a tungsten carbide-cobalt substrate. A well recognized failure mechanism is delamination at the interface between diamond and cemented carbide. High stresses at the diamond/carbide interface, due to thermal expansion and modulus mismatch, are the primary cause of in-service failure under impact loading conditions. This work was undertaken to develop a tungsten carbide-cobalt-diamond composite, which has a continuously graded interface between the diamond and tungsten carbide. The process developed comprised the following steps: (i) generation of a pore size gradient by electrochemical etching of cobalt from the surface of a partially sintered tungsten carbide-cobalt preform; (ii) chemical vapor infiltration of the porous preform with carbon by catalytic decomposition of a methane/hydrogen mixture, resulting in a graded carbon concentration; and (iii) consolidation of the carbon infiltrated preforms at 8GPa/1500°C to complete densification and to transform the carbon into diamond. Thus, the final product consists of a functionally graded WC-Co-diamond composite, with controlled distribution of the constituent phases. Tungsten carbide-cobalt powders with mean tungsten carbide particle size of 0.8mum(micro-grain) and 100 nm(nano-grain) were used as starting materials. Processing conditions were adjusted to obtain an optimal distribution of carbon in porous preforms. After high pressure/high temperature consolidation, both micro- and nano-composites showed a diffused interface between inner and outer regions of the fully dense materials. A micro-composite showed columnar-like tungsten carbide grains and faceted diamond grains in the outer region of the sintered material. The grain size of the diamond in this region was ˜2mum, and the

  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. 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.

  15. Anthropology, tooth wear, and occlusion ab origine.

    PubMed

    Young, W G

    1998-11-01

    The purpose of this essay is to emphasize that anthropology, the study of man in his environments, is a potent tool for scientific discovery and inspiration in dental science. It attempts to capture flashes of creative anthropological insight which have illuminated studies of tooth wear and occlusion in the past. While it documents contributions, understandings, and misunderstandings from Australian and New Zealand dentists, it is not a hagiography. The real saint of this essay is the Australian aborigine. For when men and women are understood in their environments, much is learned from them which challenges preconceptions of our dental science culture. The essay concludes that new, contemporary Australian culture needs to be studied by anthropological approaches if we are to understand how dental erosion is exacerbating tooth wear and damaging the occlusions of contemporary Australians. Much remains to be discovered about contemporary lifestyles, habits, and diets that lead to dental erosion, the principal cause of contemporary tooth wear in this part of the world. PMID:9823723

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. CVD diamond layers for electrochemistry

    NASA Astrophysics Data System (ADS)

    Kowalska, M.; Fabisiak, K.; Wrzyszczyński, A.; Banaszak, A.; Szybowicz, M.; Paprocki, K.; Bała, W.; Bylicki, F.

    2014-09-01

    Diamond electrodes of different morphologies and qualities were manufactured by hot filament chemical deposition (HF CVD) techniques by changing the parameters of diamond growth process. The estimation of diamond quality and identification of different carbon phases was performed by Raman spectroscopy measurements. The effect of diamond quality and amorphous carbon phase content on the electrochemical response of an obtained diamond electrode in 0.5 M H2SO4 as supporting electrolyte was investigated by cyclic voltammetry with [Fe(CN)6]4-/3- as a redox probe. The kinetic parameters such as catalytic reaction rate constant k0 and electron transfer coefficient α were determined. The obtained results show that the analytical performance of undoped diamond electrodes can be implemented just by the change of diamond layers quality.

  1. 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.

  2. 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.

  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 is on budget

    NASA Astrophysics Data System (ADS)

    Materlik, Gerhard

    2008-02-01

    Your editorial last month, entitled "The £80m black hole" (January p15), was accompanied by a picture of the Diamond Light Source, which some readers may have interpreted as being responsible for the current shortfall in funding for the Science and Technology Facilities Council (STFC). This implication is totally inaccurate and misleading.

  5. ELECTRON AMPLIFICATION IN DIAMOND.

    SciTech Connect

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

    2006-07-10

    We report on recent progress toward development of secondary emission ''amplifiers'' for photocathodes. Secondary emission gain of over 300 has been achieved in transmission mode and emission mode for a variety of diamond samples. Techniques of sample preparation, including hydrogenation to achieve negative electron affinity (NEA), have been adapted to this application.

  6. 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.

  7. 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.

  8. Multiplying Electrons With Diamond

    NASA Technical Reports Server (NTRS)

    2003-01-01

    As researchers in the Space Communications Division of NASA s Glenn Research Center in 1992, Dr. Gerald Mearini, Dr. Isay Krainsky, and Dr. James Dayton made a secondary electron emission discovery that became the foundation for Mearini s company, GENVAC AeroSpace Corporation. Even after Mearini departed Glenn, then known as Lewis Research Center, his contact with NASA remained strong as he was awarded Small Business Innovation Research (SBIR) contracts to further develop his work. Mearini s work for NASA began with the investigation of diamond as a material for the suppression of secondary electron emissions. The results of his research were the opposite of what was expected diamond proved to be an excellent emitter rather than absorber. Mearini, Krainsky, and Dayton discovered that laboratory-grown diamond films can produce up to 45 electrons from a single incident electron. Having built an electron multiplier prototype at NASA, Mearini decided to start his own company to develop diamond structures usable in electron beam devices.

  9. Ion implantation and diamond-like coatings of aluminum alloys

    SciTech Connect

    Malaczynski, G.W.; Hamdi, A.H.; Elmoursi, A.A.; Qiu, X.

    1997-04-01

    In an attempt to increase the wear resistance of some key automotive components, General Motors Research and Development Center initiated a study to determine the potential of surface modification as a means of improving the tribological properties of automotive parts, and to investigate the feasibility of mass producing such parts. This paper describes the plasma immersion ion implantation system that was designed for the study of various options for surface treatment, and it discusses bench testing procedures used for evaluating the surface-treated samples. In particular, both tribological and microstructural analyses are discussed for nitrogen implants and diamond-like hydrocarbon coatings of some aluminum alloys.

  10. 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.

  11. 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,...

  12. 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,...

  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. 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.

  17. 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.

  18. Wearing gloves in the hospital

    MedlinePlus

    Wearing gloves in the hospital helps prevent the spread of germs. This helps protect both patients and health care ... Gloves are called personal protective equipment (PPE). Other types of PPE are gowns, masks, and shoe and ...

  19. Wear resistance properties of austempered ductile iron

    SciTech Connect

    Lerner, Y.S.; Kingsbury, G.R.

    1998-02-01

    A detailed review of wear resistance properties of austempered ductile iron (ADI) was undertaken to examine the potential applications of this material for wear parts, as an alternative to steels, alloyed and white irons, bronzes, and other competitive materials. Two modes of wear were studied: adhesive (frictional) dry sliding and abrasive wear. In the rotating dry sliding tests, wear behavior of the base material (a stationary block) was considered in relationship to countersurface (steel shaft) wear. In this wear mode, the wear rate of ADI was only one-fourth that of pearlitic ductile iron (DI) grade 100-70-03; the wear rates of aluminum bronze and leaded-tin bronze, respectively, were 3.7 and 3.3 times greater than that of ADI. Only quenched DI with a fully martensitic matrix slightly outperformed ADI. No significant difference was observed in the wear of steel shafts running against ADI and quenched DI. The excellent wear performance of ADI and its countersurface, combined with their relatively low friction coefficient, indicate potential for dry sliding wear applications. In the abrasive wear mode, the wear rate of ADI was comparable to that of alloyed hardened AISI 4340 steel, and approximately one-half that of hardened medium-carbon AISI 1050 steel and of white and alloyed cast irons. The excellent wear resistance of ADI may be attributed to the strain-affected transformation of high-carbon austenite to martensite that takes place in the surface layer during the wear tests.

  20. Fractal characterization of wear-erosion surfaces

    SciTech Connect

    Rawers, J.; Tylczak, J.

    1999-12-01

    Wear erosion is a complex phenomenon resulting in highly distorted and deformed surface morphologies. Most wear surface features have been described only qualitatively. In this study wear surfaces features were quantified using fractal analysis. The ability to assign numerical values to wear-erosion surfaces makes possible mathematical expressions that will enable wear mechanisms to be predicted and understood. Surface characterization came from wear-erosion experiments that included varying the erosive materials, the impact velocity, and the impact angle. Seven fractal analytical techniques were applied to micrograph images of wear-erosion surfaces. Fourier analysis was the most promising. Fractal values obtained were consistent with visual observations and provided a unique wear-erosion parameter unrelated to wear rate. In this study stainless steel was evaluated as a function of wear erosion conditions.

  1. 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.

  2. 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.

  3. 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 ...

  4. Diamond turning considerations in the manufacture of beam shaping optics

    NASA Astrophysics Data System (ADS)

    Davis, Gregg E.; Herrit, Gary L.; Hedges, Alan R.

    2011-10-01

    Advances in diamond turning technology have offered optical designers new degrees of freedom in beam shaping optics. While designers have these new manufacturing methods at their disposal, they may not be aware of special process limitations and cost drivers. The purpose of this paper is to present some of these critical manufacturing issues. We will discuss briefly special beam shaping optic types and applications. Then in more detail we will discuss the four key diamond turning techniques and the types of optics they can produce. These four key manufacturing techniques are: standard 2 axis diamond turning, slow tool servo, fast tool servo, micromilling. During the discussion we will present surface shapes, process limitations, as well as cost drivers for each technique. In summary will we present this data in a matrix that will aid the designer in selecting manufacturing techniques and optic types.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Improving nanocrystalline diamond coatings for micro end mills

    NASA Astrophysics Data System (ADS)

    Heaney, Patrick J.

    A new method is presented for coating 300 mum diameter tungsten carbide (WC) micro end mills with diamond using a hot filament chemical vapor deposition (HF-CVD) method. This method has been developed to create uniform, conformal and continuous diamond coatings. Initial work is shown to prove the feasibility and concept of the project. This was the first work known to coat and evaluate the machining performance WC micro end mills. The performance of uncoated and coated micro end mills was evaluated by dry machining channels in 6061-T6 aluminum. The test results showed a 75% and 90% decrease in both cutting and trust forces for machining, respectfully. The coated tools produced a more predictable surface finish with no burring. These improved results are due to the superior tribological properties of diamond against aluminum. Initial results indicated severe problems with coating delamination causing complete tool failure. After proving the initial concept, new methods for optimizing the coating and improving performance were studied. Each optimization step is monitored through surface analysis techniques to monitor changes in coating morphology and diamond quality. Nucleation density was increased by improving the seed method, using ultra dispersed diamond (UDD) seed. The increase in nucleation density allowed the synthesis of coatings as thin as 60 nm. The adhesion of the coating to the tool was improved through carbon ion implantation (CII). CII is a different surface preparation technique that deactivates the effect of Co, while not weakening the tool. CII also creates a great nucleation layer which diamond can directly grow from, allowing the diamond coating to chemically bond to the substrate improving adhesion and eliminating the need for a seed layer. These thin coatings were shown to be of high quality sp3 trigonaly bonded diamond that resulted in lower machining forces with less delamination. The 90% reduction in machining forces that thin conformal

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. Microstructural effects in abrasive wear. Quarterly progress report, June 1981-January 1982

    SciTech Connect

    Kosel, T.H.; Rao, C.M.; Fernandes, M.T.; Fiore, N.F.

    1982-02-24

    This report describes research aimed at establishing quantitative relationships between microstructure and wear resistance of highly alloyed materials, including high-Cr white irons and powder metallurgy (PM) alloys now used or potentially to be used in coal mining, handling, and gasification. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion, and transfer applications. Recent work has concentrated on analysis of results. The many detailed observations obtained in the work on scratch test simulations of abrasive wear mechanisms have been summarized in drafts of three papers. The first, a study of abrasive wear mechanisms using diamond and alumina scratch tests, was included as an appendix to Quarterly Report 16/17 and has been accepted for publication in the journal Wear. Revision of the other two papers is in progress. Two papers representing our analysis of results are included as appendices to this report. The first, abrasion in multiphase alloys, was presented at the NACE conference on corrosion-erosion-wear of materials at Berkeley, California in January 1982, and will be published in the proceedings. The second, on a deformation-induced phase transformation during abrasive wear of Co-base alloys, is being submitted for publication in Metallurgical Transactions. In addition, work on the gouging abrasion resistance of the previously tested high Cr-Mo white cast irons is completed. The abstract of a short paper on the results is included as an appendix. (Note: since the appendices are, or will be, available in the open literature they have been removed from the report.)

  20. 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.

  1. 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

  2. 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.

  3. Microstructural effects in abrasive wear. Quarterly progress report, December 1980-1 June 1981. [Alloys for use in coal mining, handling, and gasification

    SciTech Connect

    Kosel, T.H.; Rao, M.C.; Shetty, H.R.; Fernandes, M.T.; Fiore, N.F.

    1981-10-29

    This report describes research aimed at establishing quantitative relationships between microstructure and wear resistance of highly alloyed materials, including high-Cr white irons and experimental Co-base and Ni-base powder metallurgy (PM) alloys now used or potentially to be used in coal mining, handling, and gasification. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion, and transfer applications. During this period, work was concentrated on analysis of results. The many detailed observations obtained in the work on scratch test simulations of abrasive wear mechanisms have been summarized in drafts of three papers. The first, A Study of Abrasive Wear Mechanisms Using Diamond and Alumina Scratch Tests, is included as an appendix to this report and is being submitted for publication. Revision of the other papers is in progress.

  4. Share-shaped durable and isometric diamond powders for superquality treatment of optics materials

    NASA Astrophysics Data System (ADS)

    Samoylova, Liliya M.; Krinskaya, Elena L.

    2002-10-01

    For the first time, developed are sphere-shaped precision diamond micropowders ASMV-RM having a number of unique properties - advanced, ordered crystal structure, improved surface morphology, maximal hardening of crystals with increase wear-resistant, with high uniformity of grains and in physico-mechanical properties, with absence of needle, sharp-angled crystals. These exclusive properties enable to provide the considerable increase of productivity of processes at essential improvement of surface quality during thin grinding and polishing of products by these micropowders. They are outside of a competition to the standard marks of diamonds of general purpose as were created for new highly perspective areas of applications focused on high technologies in electronics, optics and other branches of modern engineering. In precision micropowders ASMV-RM enormous potential of diamonds is realized. The technology of precision diamond micropowders preparation is based on results of the scientific school by Academician of the National Academy of Sciences of Ukraine V.I. Trefilov and complex approach directed on deepened influence on a material with application of modern effective technologies and the optimum technical solutions. The technology of their manufacture is referred to high technologies, and precision micropowders have created a new direction in diamond branch. Real conditions for realization of technical revolution in creation and use of a new class precision diamond micropowders are now created.

  5. 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

  6. 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.

  7. Fractal characterization of wear-erosion surfaces

    SciTech Connect

    Rawers, James C.; Tylczak, Joseph H.

    1999-12-01

    Wear erosion is a complex phenomenon resulting in highly distorted and deformed surface morphologies. Most wear surface features have been described only qualitatively. In this study wear surfaces features were quantified using fractal analysis. The ability to assign numerical values to wear-erosion surfaces makes possible mathematical expressions that will enable wear mechanisms to be predicted and understood. Surface characterization came from wear-erosion experiments that included varying the erosive materials, the impact velocity, and the impact angle. Seven fractal analytical techniques were applied to micrograph images of wear-erosion surfaces. Fourier analysis was the most promising. Fractal values obtained were consistent with visual observations and provided a unique wear-erosion parameter unrelated to wear rate.

  8. 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

  9. Improved Hardfacing for Drill Bits and Drilling Tools

    NASA Astrophysics Data System (ADS)

    Sue, Albert; Sreshta, Harry; Qiu, Bao He

    2011-01-01

    New flame spray hardfacing, DSH (DuraShell® Steel Hardfacing, US patent pending), was developed to improve thermal conductivity, abrasion wear, and erosion resistance for subterranean drilling application. The materials consisted of spherical cast WC/W2C and Ni-Si-B alloy powders. The hardfacing compositions were tailored for various processes such as flame spray and laser cladding. Typically, the hardfacing comprised hard tungsten carbide particles being uniformly distributed in a tough Ni-alloy matrix. The hardness of WC/W2C exceeded 2300 Hv.3 and that of Ni-alloy matrix varied from about 400 to 700 Hv.3. High- and low-stress abrasion resistances of these hardfacing materials were characterized and compared to the conventional hard coatings of cast WC/W2C and Ni-Cr-Si-B-Fe. The increase in thermal, wear, and erosion resistances of the hardfacing improved the durability of PDC (polycrystalline diamond compact) steel body bit and drilling tools and their cost-effective performance. Several case studies of DSH hardfacings on drill bits were described.

  10. Update on diamond and diamond-like carbon coatings

    NASA Astrophysics Data System (ADS)

    Lettington, Alan H.

    1990-10-01

    This paper reviewed the infrared uses of diamond-like carbon thin films and the potential uses of synthetic diamond layers. Diamond-like carbon is used widely as a protective anti-reflection coating for exposed germanium infrared windows and lenses and as thin protective coatings for front surface aluminium mirrors. This material is also used in protective anti-reflective coatings for zinc sulphide as the outer thin film in multi-layer designs incorporating variable index intermediate layers of germanium carbide. The maximum thickness of diamond-like carbon that can be used is often limited by the stress induced in the layer through the method of deposition and by the absorption present in the basic material. This stress and absorption can be far lower in synthetic diamond layers but there are now problems associated with the high substrate temperatures, difficulties in coating large areas uniformly and problems arising from surface scattering and low deposition rates.

  11. Diamond Machining And Mechanical Inspection Of Optical Components

    NASA Astrophysics Data System (ADS)

    Donaldson, R. R.; Patterson, S. R.; Thompson, D. C.

    1982-03-01

    Displacement measurement and motion control are discussed for rotary and linear axes of motion, as necessary for the dimensional measurement and diamond-tool machining of grazing incidence x-ray optics. Examples of available performance levels are drawn from measurements made on current developmental hardware, and are coupled with speculation on possible future extensions.

  12. Diamond machining and mechanical inspection of optical components

    NASA Astrophysics Data System (ADS)

    Donaldson, R. R.; Patterson, S. R.; Thompson, D. C.

    1981-11-01

    Displacement measurement and motion control are discussed for rotary and linear axes of motion, as necessary for the dimensional measurement and diamond-tool machining of grazing incidence X-ray optics. Examples of available performance levels are drawn from measurements made on current development hardware, and are coupled with speculation on possible future extensions.

  13. Microstructural evolution of diamond growth during HFCVD

    NASA Technical Reports Server (NTRS)

    Singh, J.

    1994-01-01

    High resolution transmission electron microscopy (HRTEM) was used to study the nucleation and growth mechanism of diamond by hot filament chemical vapor deposition (HFCVD) process. A novel technique has shown a direct evidence for the formation of the diamond-like carbon layer 8-14 nm thick in which small diamond micro-crystallites were embedded. These diamond micro-crystallites were formed as a result of transformation of diamond-like carbon into diamond. The diamond micro-crystallites present in the amorphous diamond-like carbon layer provided nucleation sites for diamond growth. Large diamond crystallites were observed to grow from these micro-crystallites. The mechanism of diamond growth will be presented based on experimental findings.

  14. Microfracture patterns of abrasive wear striations on teeth indicate directionality.

    PubMed

    Gordon, K R

    1984-03-01

    A method is described that will indicate the direction that an abrasive particle was traveling as it scored the surface of a brittle material. Light and scanning electron micrographs of glass, dentine, and enamel abraded by loose and, steel carbide, and diamond indicate that partial Hertzian fracture cones are formed at the margins of wear striations during abrasion. The bases of these fracture cones face in the direction of travel of the abrasive particle and, therefore, indicate directionality. Because this method is based only on the consistent geometry of fracturing of brittle materials, it is independent of the loading of the abrasive particle. The only other method available to determine directionality of striations is unreliable since it uses the width of striations, and, hence, is dependent upon a consistent loading regime of the abrasive particle. This new method has direct application for determining the direction of movement of the jaws during mastication in living or fossil animals. PMID:6731603

  15. 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.

  16. New Perspectives on Tooth Wear

    PubMed Central

    Lucas, Peter W.; Omar, Ridwaan

    2012-01-01

    Some of the efforts that have been made to document tooth wear are reviewed here with an emphasis on nonhuman mammals, literature with which dentists may not be very familiar. We project a change in research strategy from the description of wear at various scales of measurement towards investigation of the mechanical mechanisms that actually create the texture of a worn surface. These studies should reveal exactly how tooth tissue is lost and what aspects of the structure of dental tissues affect this. The most important aspects of the interaction between the tooth surface and wear particles would appear to be particle size, particle shape, their mechanical properties with respect to those of tooth tissues, and the influence of saliva. PMID:22536239

  17. Tool grinding machine

    DOEpatents

    Dial, Sr., Charles E.

    1980-01-01

    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 thickness may be compensated for during the grinding operation to assure the attainment of the desired cutting tool face specifications.

  18. 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.

  19. 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.

  20. Electronic properties of CVD diamond

    NASA Astrophysics Data System (ADS)

    Nebel, C. E.

    2003-03-01

    The electronic properties of chemical vapour deposited (CVD) diamond are reviewed based on data measured by transient and spectrally resolved photoconductivity experiments, photo-thermal deflection spectroscopy (PDS) and electron paramagnetic resonance (EPR) where substitutional nitrogen (P1-centre) and carbon defects (H1-centre) are detected. The results show that nominally undoped high quality polycrystalline CVD diamond is a n-type semiconductor due to the presence of substitutional nitrogen. The sub-band-gap optical absorption is governed by amorphous graphite present at grain boundaries. Spectrally resolved photoconductivity experiments measured in the same regime are partially dominated by diamond bulk properties which are comparable to single crystalline Ib and IIa diamond and partially by grain boundaries. Mobilities and drift length of carriers are discussed and compared to properties of single crystalline diamond.

  1. 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.

  2. 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

  3. Impact wear of iron rich superalloys

    NASA Technical Reports Server (NTRS)

    Wayne, S. F.; Nowotny, H.; Rice, S. L.

    1985-01-01

    The impact-sliding wear resistance of chill cast and aligned eutectic Fe-base superalloys against M42 and 17-4 PH steel counterface materials is examined. The aligned material tests were run with carbide fibers perpendicular to the counterface contact surface and the characterization focused on fracture processes as observed in the subsurface microstructure of the worn materials. Metallographic analyses were performed on specimens exposed to various numbers of repetitive impact load cycles, and for comparison, two other aligned composites were tested with the same fiber orientation under identical test conditions against hardened M42 tool steel. A strong improvement was found in wear resistance of an aligned eutectic structure as compared to the corresponding randomized chill cast structure. Experiments with the softer 17-4 counterface were characterized by transfer onto the Fe-base superalloy, and the cracks formed were oriented transverse to the relative sliding direction and occurred in a periodic fashion. Observations in subsurface regions of the worn materials indicated crack intergranularity with an occasional transgranular fracture of the M7C3 carbide phase.

  4. Evaluation of wear during the injection process with the use of optical profilometry

    NASA Astrophysics Data System (ADS)

    Hernández, P.; Díaz, M.; Covelo, E.; Ares, E.

    2012-04-01

    This article deals with the study of wear of non-conventional materials in the plastic injection industry, particularly in inserts for reusable injection molds. A methodology for the analysis of wear is proposed using new measurement parameters. Superficial parameters like roughness average (Ra) have proven not to be quite effective for this purpose. Therefore new coefficients are suggested, as the Minimum Wear Area (MWA), which takes advantage of the collected data and appears to be a better choice for wear characterization. A Polyamide with 30% load of fiberglass has been injected into two cavities manufactured in different material (aluminum and brass) and with the same geometry, in which the wear at different points has been evaluated. We have used interferometry and an optical microscope as measurement tools. Finite element analysis and simulation software has also been used.

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. Should School Nurses Wear Uniforms?

    ERIC Educational Resources Information Center

    Journal of School Health, 2001

    2001-01-01

    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  10. Diamonds in the Sky

    NASA Astrophysics Data System (ADS)

    Brotherton, M.

    2004-12-01

    My first science fiction novel, Star Dragon, just recently available in paperback from Tor, features a voyage to the cataclysmic variable star system SS Cygni. My second novel, Spider Star, to appear early in 2006, takes place in and around a dark matter ``planet'' orbiting a neutron star. Both novels are ``hard'' science fiction, relying on accurate physics to inform the tales. It's possible to bring to life abstract concepts like special relativity, and alien environments like accretion disks, by using science fiction. Novels are difficult to use in a science class, but short stories offer intriguing possibilities. I'm planning to edit an anthology of hard science fiction stories that contain accurate science and emphasize fundamental ideas in modern astronomy. The working title is Diamonds in the Sky. The collection will be a mix of original stories and reprints, highlighting challenging concepts covered in a typical introductory astronomy course. Larry Niven's classic story, ``Neutron Star," is an excellent demonstration of extreme tidal forces in an astronomical context. Diamonds in the Sky will include forewards and afterwards to the stories, including discussion questions and mathematical formulas/examples as appropriate. I envision this project will be published electronically or through a print-on-demand publisher, providing long-term availabilty and keeping low cost. I encourage interested parties to suggest previously published stories, or to suggest which topics must be included.

  11. Adhesion and wear behaviour of NCD coatings on Si3N4 by micro-abrasion tests.

    PubMed

    Silva, F G; Neto, M A; Fernandes, A J S; Costa, F M; Oliveira, F J; Silva, R F

    2009-06-01

    Nanocrystalline diamond (NCD) coatings offer an excellent alternative for tribological applications, preserving most of the intrinsic mechanical properties of polycrystalline CVD diamond and adding to it an extreme surface smoothness. Silicon nitride (Si3N4) ceramics are reported to guarantee high adhesion levels to CVD microcrystalline diamond coatings, but the NCD adhesion to Si3N4 is not yet well established. Micro-abrasion tests are appropriate for evaluating the abrasive wear resistance of a given surface, but they also provide information on thin film/substrate interfacial resistance, i.e., film adhesion. In this study, a comparison is made between the behaviour of NCD films deposited by hot-filament chemical vapour deposition (HFCVD) and microwave plasma assisted chemical vapour deposition (MPCVD) techniques. Silicon nitride (Si3N4) ceramic discs were selected as substrates. The NCD depositions by HFCVD and MPCVD were carried out using H2-CH4 and H2-CH4-N2 gas mixtures, respectively. An adequate set of growth parameters was chosen for each CVD technique, resulting in NCD films having a final thickness of 5 microm. A micro-abrasion tribometer was used, with 3 microm diamond grit as the abrasive slurry element. Experiments were carried out at a constant rotational speed (80 r.p.m.) and by varying the applied load in the range of 0.25-0.75 N. The wear rate for MPCVD NCD (3.7 +/- 0.8 x 10(-5) mm3 N(-1) m(-1)) is compatible with those reported for microcrystalline CVD diamond. The HFCVD films displayed poorer adhesion to the Si3N4 ceramic substrates than the MPCVD ones. However, the HFCVD films show better wear resistance as a result of their higher crystallinity according to the UV Raman data, despite evidencing premature adhesion failure. PMID:19504945

  12. 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.

  13. 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.

  14. Invited Article: Precision nanoimplantation of nitrogen vacancy centers into diamond photonic crystal cavities and waveguides

    NASA Astrophysics Data System (ADS)

    Schukraft, M.; Zheng, J.; Schröder, T.; Mouradian, S. L.; Walsh, M.; Trusheim, M. E.; Bakhru, H.; Englund, D. R.

    2016-05-01

    We demonstrate a self-aligned lithographic technique for precision generation of nitrogen vacancy (NV) centers within photonic nanostructures on bulk diamond substrates. The process relies on a lithographic mask with nanoscale implantation apertures for NV creation, together with larger features for producing waveguides and photonic nanocavities. This mask allows targeted nitrogen ion implantation, and precision dry etching of nanostructures on bulk diamond. We demonstrate high-yield generation of single NVs at pre-determined nanoscale target regions on suspended diamond waveguides. We report implantation into the mode maximum of diamond photonic crystal nanocavities with a single-NV per cavity yield of ˜26% and Purcell induced intensity enhancement of the zero-phonon line. The generation of NV centers aligned with diamond photonic structures marks an important tool for scalable production of optically coupled spin memories.

  15. 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.

  16. 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.

  17. Diagnostics of wear in aeronautical systems

    NASA Technical Reports Server (NTRS)

    Wedeven, L. D.

    1979-01-01

    The use of appropriate diagnostic tools for aircraft oil wetted components is reviewed, noting that it can reduce direct operating costs through reduced unscheduled maintenance, particularly in helicopter engine and transmission systems where bearing failures are a significant cost factor. Engine and transmission wear modes are described, and diagnostic methods for oil and wet particle analysis, the spectrometric oil analysis program, chip detectors, ferrography, in-line oil monitor and radioactive isotope tagging are discussed, noting that they are effective over a limited range of particle sizes but compliment each other if used in parallel. Fine filtration can potentially increase time between overhauls, but reduces the effectiveness of conventional oil monitoring techniques so that alternative diagnostic techniques must be used. It is concluded that the development of a diagnostic system should be parallel and integral with the development of a mechanical system.

  18. 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.

  19. Effect of diamond burs on process and damage involving in vitro dental resurfacing of a restorative porcelain

    NASA Astrophysics Data System (ADS)

    Yin, Ling; Han, Yi-Gang; Song, Xiao-Fei; Wang, Hui

    2007-09-01

    This work reports on the effect of diamond burs with coarse, medium and fine grit sizes and nickel or chromium coatings on in vitro dental resurfacing of a restorative porcelain. Process parameters such as tangential and normal forces, surface roughness, surface damage and morphology were studied as a function of removal rate using the different burs. At the lower removal rate, the differences for both the tangential and the normal forces were not significant among the coarse, medium and fine burs. However, when the porcelain was removed at the higher removal rate, both the tangential and the normal forces were markedly higher using the fine bur than those using the medium and coarse burs. Surface roughness values in terms of arithmetic mean and maximum roughness decreased significantly with a decrease in diamond grit size. The scale of surface damage in the form of brittle fracture decreased, and more transitions from brittle removal to ductile flow were observed when using finer grit diamond burs. In a comparison of the diamond bur topographies before and after dental finishing, it was found that minimal wear occurred on the nickel-coated coarse diamond bur, while minor abrasive wear occurred on the nickel-coated medium and chromium-coated fine burs.

  20. 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)...

  1. 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.

  2. 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.

  3. 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.

  4. Diamond and Diamond-Like Materials as Hydrogen Isotope Barriers

    SciTech Connect

    Foreman, L.R.; Barbero, R.S.; Carroll, D.W.; Archuleta, T.; Baker, J.; Devlin, D.; Duke, J.; Loemier, D.; Trukla, M.

    1999-07-10

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The purpose of this project was to develop diamond and diamond-like thin-films as hydrogen isotope permeation barriers. Hydrogen embrittlement limits the life of boost systems which otherwise might be increased to 25 years with a successful non-reactive barrier. Applications in tritium processing such as bottle filling processes, tritium recovery processes, and target filling processes could benefit from an effective barrier. Diamond-like films used for low permeability shells for ICF and HEDP targets were also investigated. Unacceptable high permeabilities for hydrogen were obtained for plasma-CVD diamond-like-carbon films.

  5. Wear processes in manufacturing. ASTM special technical publication 1362

    SciTech Connect

    Bahadur, S.B.; Magee, J.

    1998-07-01

    The importance of tribological phenomena in engineering has long been recognized. The evidence for this lies in the extensive studies on tool wear performed over many decades. The same is the case with studies related to the friction and lubrication in deformation processing as evidenced by a number of conferences and related publications. In spite of this, the interaction between the tribologists and manufacturing researchers has not been great. The objective of this symposium was to provide a forum for these researchers for a mutually beneficial interaction. The collection of papers published in this volume may be grouped into the following categories. These categories are: abrasion in ceramic grinding, wear of cutting tools, friction in vibratory conveyers, and erosion in manufacturing. Separate abstracts were prepared for 11 papers.

  6. Conductive polycrystalline diamond probes for local anodic oxidation lithography

    NASA Astrophysics Data System (ADS)

    Ulrich, A. J.; Radadia, A. D.

    2015-11-01

    This is the first report characterizing local anodic oxidation (LAO) lithography performed using conductive monolithic polycrystalline diamond (MD) and conductive polycrystalline diamond-coated (DC) tips and comparing it to the diamond-like carbon-coated and metal-coated silicon tips. The range and the rate of increase in the lithographic linewidth and height with tip bias (dw/dV and dh/dV) differed based on the tip material. The DC tips resulted in wider and taller lines and a higher dw/dV and dh/dV compared to metal-coated tips with a similar force constant (k Avg). The metal-coated and the DC tips with comparable k Avg showed comparable threshold voltages, whereas the MD tips with similar k Avg showed a higher threshold voltage. The MD tips exhibited less than half the height and nearly half the dw/dV and dh/dV obtained with the metal-coated tips with similar k Avg, thus also resulting in a smaller width at -10 V. The linewidths were found to be proportional to the inverse of the log of write speed (v) for all the tips; however, the proportionality constant varied with tip material; the DC tips had larger values, and the MD and the metal-coated tips had comparable values. When varying the speed, the height was found to be a sigmoidal function of width, with the MD probes achieving lower height compared to the metal-coated and the DC tips with comparable k Avg. This study expands the application of monolithic conductive polycrystalline diamond (PCD) probes with outstanding wear resistance to fine LAO lithography.

  7. Conductive polycrystalline diamond probes for local anodic oxidation lithography.

    PubMed

    Ulrich, A J; Radadia, A D

    2015-11-20

    This is the first report characterizing local anodic oxidation (LAO) lithography performed using conductive monolithic polycrystalline diamond (MD) and conductive polycrystalline diamond-coated (DC) tips and comparing it to the diamond-like carbon-coated and metal-coated silicon tips. The range and the rate of increase in the lithographic linewidth and height with tip bias (dw/dV and dh/dV) differed based on the tip material. The DC tips resulted in wider and taller lines and a higher dw/dV and dh/dV compared to metal-coated tips with a similar force constant (k(Avg)). The metal-coated and the DC tips with comparable k(Avg) showed comparable threshold voltages, whereas the MD tips with similar k(Avg) showed a higher threshold voltage. The MD tips exhibited less than half the height and nearly half the dw/dV and dh/dV obtained with the metal-coated tips with similar k Avg, thus also resulting in a smaller width at -10 V. The linewidths were found to be proportional to the inverse of the log of write speed(v) for all the tips; however, the proportionality constant varied with tip material; the DC tips had larger values, and the MD and the metal-coated tips had comparable values. When varying the speed, the height was found to be a sigmoidal function of width, with the MD probes achieving lower height compared to the metal-coated and the DC tips with comparable k(Avg). This study expands the application of monolithic conductive polycrystalline diamond (PCD) probes with outstanding wear resistance to fine LAO lithography. PMID:26501841

  8. Age estimation of an Indian population by using the Kim's scoring system of occlusal tooth wear

    PubMed Central

    Telang, Lahari A.; Patil, Karthikeya; Mahima, V. G.

    2014-01-01

    Context: Age is one of the prime factors employed to establish the identity of an individual and the use of teeth for this purpose has been considered reliable. Tooth wear is widely accepted as a physiological consequence of aging and evaluation of tooth wear can be a simple and convenient tool to estimate age in adults. Aims: The present study was conducted to record the degree of tooth wear among Indian adults and to estimate their ages from the degree of tooth wear based on Kim's scoring system. Materials and Methods: Dental stone casts of 120 participants were used to assess the degree of occlusal tooth wear based on the criteria given by Kim et al. Statistical Analysis Used: The age of all subjects was estimated based on these scores using multiple regression analysis function. Results: The degree of tooth wear showed a significant positive correlation with age in each and every examined tooth of both males and females. The predicted age was within ± 5 years of actual age in 70% of males and 68.3% females, and within ± 3 years of actual age in 50% of males and 50.1% of females. Conclusions: Kim's scoring system has proven to be a useful tool in estimation of age using occlusal wear in an Indian population with a high level of accuracy in adults. PMID:24695780

  9. Tribological Evaluation of Nanostructured Diamond Coatings and CoCr against Ultra-High Molecular Weight Polyethylene

    PubMed Central

    Hill, Michael R.; Catledge, Shane A.; Konovalov, Valeriy; Clem, William C.; Chowdhury, Shafiul A.; Etheridge, Brandon S.; Stanishevsky, Andrei; Lemons, Jack E.; Vohra, Yogesh K.; Eberhardt, Alan W.

    2008-01-01

    Background Some loss of joint prostheses has been attributed to osteolytic phenomena leading to loosening and associated with debris from wear of polyethylene articulating against metal alloys. Reduced polyethylene wear has been reported with ceramics serving as an alternative counterface. Methods Nanostructured Diamond (NSD) coatings were deposited onto Ti6A14V by microwave plasma-assisted chemical vapor deposition, with both hydrogen-rich (H-NSD) and helium-rich (He-NSD) feedgas mixtures. Pin-on-disk wear tests of polyethylene against NSD and CoCr were performed in serum lubrication at body temperature. Scanning electron microscopy was used to examine surface morphology, and nanoindentation was used to determine hardness and modulus of the polyethylene pins. Raman spectroscopy, surface roughness, and wettability analyses of NSD coatings were performed. Results Raman spectroscopy confirmed sp2 and sp3 bonded carbon. No significant differences in wear factors were found between polyethylene on H-NSD, He-NSD, and CoCr, despite higher roughness and friction coefficient for the He-NSD and H-NSD coatings, compared to CoCr. Contact angles for the diamond coatings were reduced following the wear tests, indicating that these surfaces became more hydrophilic. Multiple pimples were observed on pins articulated against CoCr, and a single, large protuberance was observed in polyethylene-on-NSD These features were conjectured to be re-consolidated polyethylene particles. Nanoindentation modulus and hardness of the worn polyethylene surfaces were lower for polyethylene-on-diamond than for polyethylene-on-CoCr. Conclusions As a counterface to polyethylene, the NSD coatings produced wear factors comparable to CoCr in the present pin-on-disk tests. Thus, NSD-coated Ti6A14V shows promise for use in joint replacement bearing applications. PMID:17853416

  10. Research on a diamond turning method for large aspherical mirrors

    NASA Astrophysics Data System (ADS)

    Han, Cheng-Shun; Zhang, Long-Jiang; Ren, Yong; Sun, Tao

    2010-05-01

    Large size aspherical optic surfaces have gained significant importance and indispensability because of their desirable properties, and the fast growing demand needs urgently efficient and economical fabrication methods. A precision diamond turning machine with rotating tool feed and fast tool servo systems special for turning large asphercial mirrors is introduced, and a method to determine the best-fit sphere for this diamond turning method is also presented. A precise in-site measurement of the processing optical mirror is planned to construct on this machine tool in order to enhance the precision and efficiency, and reduce the production cost. The lateral shearing interferometer is known for being made small and having almost common-path beams that makes insensitive to mechanical vibrations and air turbulence, so it can be very suitable for measurement on the spot.

  11. Wear prediction in a fluidized bed

    SciTech Connect

    Boyle, E.J.; Rogers, W.A.

    1993-06-01

    A procedure to model the wear of surfaces exposed to a fluidized bed is formulated. A stochastic methodology adapting the kinetic theory of gases to granular flows is used to develop an impact wear model. This uses a single-particle wear model to account for impact wear from all possible-particle collisions. An adaptation of a single-particle abrasion model to describe the effects of many abrading particles is used to account for abrasive wear. Parameters describing granular flow within the fluidized bed, necessary for evaluation of the wear expressions, are determined by numerical solution of the fluidized bed hydrodynamic equations. Additional parameters, describing the contact between fluidized particles and the wearing surface, are determined by optimization based on wear measurements. The modeling procedure was used to analyze several bubbling and turbulent fluidized bed experiments with single-tube and tube bundle configurations. Quantitative agreement between the measured and predicted wear rates was found, with some exceptions for local wear predictions. This work demonstrates a methodology for wear predictions in fluidized beds.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. Properties of interfaces of diamond

    NASA Astrophysics Data System (ADS)

    Nemanich, R. J.; Bergman, L.; Turner, K. F.; van der Weide, J.; Humphreys, T. P.

    1993-04-01

    Results related to two different interface aspects involving diamond are described: (1) the initial states of CVD diamond film growth, and (2) the negative electron affinity and formation of metal-diamond interfaces. The surface and interface properties are probed with STM, Raman scattering/photoluminescence and angle-resolved UV photoemission spectroscopy (ARUPS). STM measurements of diamond nuclei on Si after various plasma growth processes show both flat and hillocked structures characteristics of 2-dimensional and 3-dimensional growth modes, respectively. STS measurements show distinct I- V characteristics of the nuclei and the substrate. The presence of optical defects and the diamond quality are studied with micro-Raman/photoluminescence measurements. The results indicate an increased density of impurity-related defects during the initial stages of growth. The interface properties of Ti on natural crystal (1 1 1) and (1 0 0) surfaces are studied with ARUPS using 21.2 eV HeI emission. Prior to deposition the diamond (1 1 1) is chemically cleaned, and a sharp (0.5 eV FWHM) peak is observed at the position of the conduction band minimum, indicating a negative electron affinity surface. After a subsequent argon plasma clean this peak disappears, while the spectrum shows a shift of 0.5 eV towards higher energies. Upon sub-monolayer titanium deposition on (1 1 1) diamond, the negative electron affinity peak reappears. Further titanium depositions causes this titanium-induced negative electron affinity peak to be attenuated, indicating that the emission originates from the interface. A similar experiment, done on the diamond (1 0 0) surface, however, does not result in a negative electron affinity. By determining the relative positions of the diamond valence band edge and the titanium Fermi level, the Schottky barrier height of titanium on diamond is measured. A model, based on the Schottky barrier height of titanium on diamond, and the work function of titanium, is

  17. 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.

  18. 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.

  19. Rod Control Assemblies Wear Mechanisms

    SciTech Connect

    Kaczorowski, Damien; Georges, Jean-Mary; Bec, Sandrine; Vannes, Andre-Bernard; Tonck, Andre; Vernot, Jean-Philippe

    2002-07-01

    In nuclear power plants, slender tubular components are subjected to vibrations in a PHTW environment. As a result, the two contacting surfaces, tubes and their guides undergo impact at low contact pressures. The components are usually made of stainless steel and it was found that the influence of the PHTW, combined with other actions (such as corrosion, erosion, squeeze film effect, third body effect and cavitation) leads to a particular wear of the material. Therefore, this paper aims to show that the colloidal oxides, formed on the steel surfaces in PHTW, play a principal role in the wear of the surfaces. Actually, due to the specific kinematic conditions of the contact, the flow of compacted oxides abrades the surfaces. (authors)

  20. 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.