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Sample records for hvof sprayed inconel

  1. Mechanical Property of HVOF Inconel 718 Coating for Aeronautic Repair

    NASA Astrophysics Data System (ADS)

    Lyphout, Christophe; Fasth, Angelica; Nylen, Per

    2014-02-01

    The module of elasticity is one of the most important mechanical properties defining the strength of a material which is a prerequisite to design a component from its early stage of conception to its field of application. When a material is to be thermally sprayed, mechanical properties of the deposited layers differ from the bulk material, mainly due to the anisotropy of the highly textured coating microstructure. The mechanical response of the deposited layers significantly influences the overall performance of the coated component. It is, therefore, of importance to evaluate the effective module of elasticity of the coating. Conventional experimental methods such as microindentation, nanoindentation and four-point bending tests have been investigated and their results vary significantly, mainly due to inhomogeneous characteristics of the coating microstructure. Synchrotron radiation coupled with a tensile test rig has been proposed as an alternative method to determine the coating anisotropic elastic behavior dependence on crystallographic orientations. The investigation was performed on Inconel 718 (IN718) HVOF coatings sprayed on IN718 substrates. Combining these experimental techniques yield a deeper understanding of the nature of the HVOF coating Young's modulus and thus a tool for Design Practice for repair applications.

  2. A new HVOF thermal spray concept

    SciTech Connect

    Browning, J.A.; Matus, R.J.; Richter, H.J.

    1995-12-31

    HVOF plays an important role in the commercial production of thermal spray coatings from powder. Initially, both the chamber and duct modes were used. Today, the best coatings are produced by high-pressure chamber guns with some manufacturers having switched their designs from the duct to the chamber mode. There has been little or no spraying of wire with HVOF equipment. A new HVOF process -- the shock-stabilized mode -- compliments chamber powder spraying by offering the user a very simple device for wire use. Calculations show that the much higher jet velocities of the chamber mode make that design the better suited for use with powder. Conversely, the greatly increased jet temperatures offered by shock-stabilized combustion give extremely high wire melt-off rates.

  3. Oxidation in HVOF-sprayed steel

    SciTech Connect

    Smith, M.F.; Neiser, R.A.; Dykhuizen, R.C.

    1997-08-01

    It is widely held that most of the oxidation in thermally sprayed coatings occurs on the surface of the droplet after it has flattened. The evidence in this paper suggests that, for the conditions studied here, oxidation of the top surface of flattened droplets is not the dominant oxidation mechanism. In this study, a mild steel wire (AISI 1025) was sprayed using a high-velocity oxy-fuel (HVOF) torch onto copper and aluminum substrates. Ion milling and Auger spectroscopy were used to examine the distribution of oxides within individual splats. Conventional metallographic analysis was also used to study oxide distributions within coatings that were sprayed under the same conditions. An analytical model for oxidation of the exposed surface of a splat is presented. Based on literature data, the model assumes that diffusion of iron through a solid FeO layer is the rate limiting factor in forming the oxide on the top surface of a splat. An FeO layer only a few thousandths of a micron thick is predicted to form on the splat surface as it cools. However, the experimental evidence shows that the oxide layers are typically 100x thicker than the predicted value. These thick, oxide layers are not always observed on the top surface of a splat. Indeed, in some instances the oxide layer is on the bottom, and the metal is on the top. The observed oxide distributions are more consistently explained if most of the oxide formed before the droplets impact the substrate.

  4. Nanocrystalline NiAl Coating Prepared by HVOF Thermal Spraying

    NASA Astrophysics Data System (ADS)

    Enayati, M. H.; Karimzadeh, F.; Tavoosi, M.; Movahedi, B.; Tahvilian, A.

    2011-03-01

    Nanocrystalline NiAl intermetallic powder was prepared by mechanical alloying (MA) of Ni50Al50 powder mixture and then deposited on low carbon steel substrates by high velocity oxy fuel (HVOF) thermal spray technique using two sets of spraying parameters. X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), differential scanning calorimetry (DSC), and hardness test were used to characterize the prepared powders and coatings. The MA of Ni50Al50 powder mixture led to the formation of NiAl intermetallic compound. The resulting powder particles were three dimensional in nature with irregular morphology and a crystallite size of ~10 nm. This powder was thermally sprayed by HVOF technique to produce coating. The deposited coating had a nanocrystalline structure with low oxide and porosity contents. The hardness of coatings was in the range of 5.40-6.08 GPa, which is higher than that obtained for NiAl coating deposited using conventional powders.

  5. HVOF-Sprayed Nylon-11 + Nanodiamond Composite Coatings: Production & Characterization

    NASA Astrophysics Data System (ADS)

    Stravato, A.; Knight, R.; Mochalin, V.; Picardi, S. C.

    2008-12-01

    High velocity oxy-fuel (HVOF) combustion spraying has previously been shown to be a viable method for depositing polymer and polymer/ceramic composite coatings. The addition of hard particulate reinforcing phases to soft polymeric matrices should improve their durability and sliding wear performance. Nanosized diamond is an ideal reinforcing phase, owing to its high hardness, low coefficient of friction, and desirable thermal properties. Composite coatings comprising a Nylon-11 matrix reinforced with nanodiamonds have been successfully produced by HVOF. An important challenge is preserving the structure of the nanoparticles after thermal spray deposition and achieving their uniform dispersion within the polymeric matrix. Raman spectroscopy and x-ray diffraction were used to confirm the presence and retention of nanodiamonds after HVOF deposition. Understanding of the role of process parameters, including the content of reinforcing phase in the matrix and powder preparation route is necessary. Nanoindentation studies demonstrated an improvement in creep behavior and recovery of the HVOF Nylon-11/nanodiamond composites subjected to deformation.

  6. HVOF thermal spraying: An alternative to hard chrome plating

    SciTech Connect

    Bolles, D.C.

    1995-10-01

    In recent years pressure to find alternatives to chromium electroplating has accelerated dramatically. While it is not likely that the process will be banned completely, the trend points to severe limitations. Industries must now look closely at their applications, and actively consider alternatives to hard chrome plaint. One of the most viable alternatives in thermal spraying. Recent advances in high-velocity oxygen fuel (HVOF) technology offer an environmentally safer, cleaner and less-expensive alternative to chromium plating. It has been shown here that HVOF coatings can be used as chromium plating alternatives for many different applications. The HVOF process offers several advantages over chromium plaint including thicker coating capability, no part size restrictions and no hazardous waste products. A number of HVOF coatings have had excellent results in laboratory and field testing, and can be considered as effective replacements for hard chrome. The choice for a suitable replacement can only be made after careful assessment of the conditions associated with the application in question.

  7. AE Monitoring and Analysis of HVOF Thermal Spraying Process

    NASA Astrophysics Data System (ADS)

    Faisal, N. H.; Ahmed, R.; Reuben, R. L.; Allcock, B.

    2011-09-01

    This work presents an in situ monitoring of HVOF thermal spraying process through an acoustic emission (AE) technique in an industrial coating chamber. Single layer thermal spraying on substrate was carried out through slits. Continuous multilayer thermal spraying onto the sample without slit was also conducted. The AE was measured using a broadband piezoelectric AE sensor positioned on the back of the substrate. A mathematical model has been developed to determine the total kinetic energy of particles impacting the substrate through slits. Results of this work demonstrate that AE associated with particle impacts can be used for in situ monitoring of coating process. Results also show that the amplitude and AE energy is related to the spray gun transverse speed and the oxy-fuel pressure. The measured AE energy was found to vary with the number of particles impacting the substrate, determined using the mathematical model.

  8. Numerical Modeling of Suspension HVOF Spray

    NASA Astrophysics Data System (ADS)

    Jadidi, M.; Moghtadernejad, S.; Dolatabadi, A.

    2016-02-01

    A three-dimensional two-way coupled Eulerian-Lagrangian scheme is used to simulate suspension high-velocity oxy-fuel spraying process. The mass, momentum, energy, and species equations are solved together with the realizable k-ɛ turbulence model to simulate the gas phase. Suspension is assumed to be a mixture of solid particles [mullite powder (3Al2O3·2SiO2)], ethanol, and ethylene glycol. The process involves premixed combustion of oxygen-propylene, and non-premixed combustion of oxygen-ethanol and oxygen-ethylene glycol. One-step global reaction is used for each mentioned reaction together with eddy dissipation model to compute the reaction rate. To simulate the droplet breakup, Taylor Analogy Breakup model is applied. After the completion of droplet breakup, and solvent evaporation/combustion, the solid suspended particles are tracked through the domain to determine the characteristics of the coating particles. Numerical simulations are validated against the experimental results in the literature for the same operating conditions. Seven or possibly eight shock diamonds are captured outside the nozzle. In addition, a good agreement between the predicted particle temperature, velocity, and diameter, and the experiment is obtained. It is shown that as the standoff distance increases, the particle temperature and velocity reduce. Furthermore, a correlation is proposed to determine the spray cross-sectional diameter and estimate the particle trajectories as a function of standoff distance.

  9. Validation of HVOF Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Hydraulic/Pneumatic Actuators

    DTIC Science & Technology

    2007-12-01

    Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Hydraulic/Pneumatic Actuators December 2007 Report Documentation Page Form...00-00-2007 to 00-00-2007 4. TITLE AND SUBTITLE Validation of HVOF Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Hydraulic...Advantages and Limitations of HVOF Thermal Spraying as a Chrome Replacement

  10. The functional TiO2-biodegradable plastic composite material produced by HVOF spraying process.

    PubMed

    Bang, Hee-Seon; Bang, Han-Sur; Lee, Yoon-Ki

    2007-11-01

    Photocatalytic TiO2 coatings on bio-degradable plastic(polybutylene succinate: PBS) were prepared by HVOF spraying using three kinds of agglomerated powders (P200: 200 nm, P30: 30 nm, P7: 7 nm). The microstructures of the coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of the coatings was evaluated by photo degradation of gaseous acetaldehyde. For both the HVOF sprayed P200 and P30 coatings, high anatase ratio of 100% was achieved, regardless of the fuel gas pressure. On the other hand, for the HVOF sprayed P7 coating, the anatase ratio decreased from 100% to 49.1% with increasing fuel gas pressure. This decrease may be attributed to the much higher susceptibility to heat of the 7 nm agglomerated powders than the 30 nm and 200 nm agglomerated powders. In terms of the photocatalytic efficiency, HVOF sprayed P200 and P30 coatings seemed to outperform the P7 coatings because of their higher anatase ratios. However, the HVOF sprayed P7 coatings did not show photocatalytic activity possibly because of the extremely small reaction surface area to the photo-catalytic activity and low anatase ratio. Therefore, the present study found that functional PBS plastic with photocatalytic performance could be produced by spraying of ceramics such as TiO2.

  11. Effect of particle state on the adhesive strength of HVOF sprayed metallic coating

    NASA Astrophysics Data System (ADS)

    Li, Chang-Jiu; Wang, Yu-Yue

    2002-12-01

    NiCrBSi and Ni-50Cr coatings were deposited using the high velocity oxygen fuel (HVOF) spray process under different spray parameters with two powders of different sizes to clarify the influence of the melting state of spray particles on the adhesive strength of the coating. The adhesive strength of the coating was estimated according to the American Society for Testing and Materials (ASTM) C633-79. The melting state of the spray droplet was examined from the coating microstructure. It was found that the melting state of spray particles had a significant effect on the adhesive strength of HVOF sprayed Ni-based coatings. The significant melting of the spray particle did not contribute to the increase in the adhesion of HVOF metallic coatings. On the other hand, the deposition of a partially melted large particle contributed to the substantial improvement of adhesive strength of the HVOF coating. The subsequent coating presented a dense microstructure and yielded an adhesive strength of more than 76 MPa, which was double that of the coating deposited with completely molten particles. It can be suggested that the good melting of the spray particle is mainly related to the mechanical interlocking effect, which reaches the limited and approximately defined adhesive strength up to 40 50 MPa.

  12. The Instrumented Indentation Study of HVOF-Sprayed Hardmetal Coatings

    NASA Astrophysics Data System (ADS)

    Houdková, Šárka; Bláhová, Olga; Zahálka, František; Kašparová, Michaela

    2012-01-01

    Elastic-plastic properties, namely, hardness and Young's modulus, of four HVOF-sprayed hardmetal coatings were measured by instrumented indentation using Oliver-Pharr method Nanoindenter XP MTS with a continuous stiffness measurement (CSM) module. The results show that with sufficient number of CSM measurements, one can distinguish between indents made in the hard particles and indents made in the binder material. This can be accomplished by analyzing the plots of hardness and Young's modulus versus load (or versus indentation depth). Further development of the dependence curves enables the load (or indentation depth) to be set to correspond to the point of transition from a single structure component to the composite material and to determine the properties of both. Comparison of results of CSM measurement with the results of single indentation measurement at a defined load reveals a new perspective on the origin of the indentation size effect in hardmetal coatings. The measurements show that the increase in both the hardness and Young's modulus with decreasing load is caused mainly by the predominant influence of hard particles in the coatings.

  13. Production of Babbitt Coatings by High Velocity Oxygen Fuel (HVOF) Spraying

    NASA Astrophysics Data System (ADS)

    Nascimento, A. R. C.; Ettouil, F. B.; Moreau, C.; Savoie, S.; Schulz, R.

    2017-10-01

    This work presents HVOF as an alternative means to produce dense Babbitt coatings by thermal spray. A radial injection setup and low fuel flow rates were used to minimize heat transfer to the low melting point alloy. In-flight particle diagnostic systems were used to correlate spray parameters with the changes in particle velocity and thermal radiation intensity. The use of particles with larger diameters resulted in higher deposition efficiencies. It was shown that HVOF Babbitt coatings combine a dense structure and a fine distribution of intermetallic phases when compared to more traditional babbitting techniques.

  14. Production of Babbitt Coatings by High Velocity Oxygen Fuel (HVOF) Spraying

    NASA Astrophysics Data System (ADS)

    Nascimento, A. R. C.; Ettouil, F. B.; Moreau, C.; Savoie, S.; Schulz, R.

    2017-08-01

    This work presents HVOF as an alternative means to produce dense Babbitt coatings by thermal spray. A radial injection setup and low fuel flow rates were used to minimize heat transfer to the low melting point alloy. In-flight particle diagnostic systems were used to correlate spray parameters with the changes in particle velocity and thermal radiation intensity. The use of particles with larger diameters resulted in higher deposition efficiencies. It was shown that HVOF Babbitt coatings combine a dense structure and a fine distribution of intermetallic phases when compared to more traditional babbitting techniques.

  15. Effect of Plasma Nitriding and Nitrocarburizing on HVOF-Sprayed Stainless Steel Coatings

    NASA Astrophysics Data System (ADS)

    Park, Gayoung; Bae, Gyuyeol; Moon, Kyungil; Lee, Changhee

    2013-12-01

    In this work, the effects of plasma nitriding (PN) and nitrocarburizing on HVOF-sprayed stainless steel nitride layers were investigated. 316 (austenitic), 17-4PH (precipitation hardening), and 410 (martensitic) stainless steels were plasma-nitrided and nitrocarburized using a N2 + H2 gas mixture and the gas mixture containing C2H2, respectively, at 550 °C. The results showed that the PN and nitrocarburizing produced a relatively thick nitrided layer consisting of a compound layer and an adjacent nitrogen diffusion layer depending on the crystal structures of the HVOF-sprayed stainless steel coatings. Also, the diffusion depth of nitrogen increased when a small amount of C2H2 (plasma nitrocarburizing process) was added. The PN and nitrocarburizing resulted in not only an increase of the surface hardness, but also improvement of the load bearing capacity of the HVOF-sprayed stainless steel coatings because of the formation of CrN, Fe3N, and Fe4N phases. Also, the plasma-nitrocarburized HVOF-sprayed 410 stainless steel had a superior surface microhardness and load bearing capacity due to the formation of Cr23C6 on the surface.

  16. X-ray photoelectron spectroscopy study of the passive films formed on thermally sprayed and wrought Inconel 625

    NASA Astrophysics Data System (ADS)

    Bakare, M. S.; Voisey, K. T.; Roe, M. J.; McCartney, D. G.

    2010-11-01

    There is a well known performance gap in corrosion resistance between thermally sprayed corrosion resistant coatings and the equivalent bulk materials. Interconnected porosity has an important and well known effect, however there are additional relevant microstructural effects. Previous work has shown that a compositional difference exists between the regions of resolidified and non-melted material that exist in the as-sprayed coatings. The resolidified regions are depleted in oxide forming elements due to formation of oxides during coating deposition. Formation of galvanic cells between these different regions is believed to decrease the corrosion resistance of the coating. In order to increase understanding of the details of this effect, this work uses X-ray photoelectron spectroscopy (XPS) to study the passive films formed on thermally sprayed coatings (HVOF) and bulk Inconel 625, a commercially available corrosion resistant Ni-Cr-Mo-Nb alloy. Passive films produced by potentiodynamic scanning to 400 mV in 0.5 M sulphuric acid were compared with air-formed films. The poorer corrosion performance of the thermally sprayed coatings was attributed to Ni(OH) 2, which forms a loose, non-adherent and therefore non-protective film. The good corrosion resistance of wrought Inconel 625 is due to formation of Cr, Mo and Nb oxides.

  17. Duplex coating of electroless nickel and HVOF (high-velocity oxygen fuel) sprayed WC-Co

    NASA Astrophysics Data System (ADS)

    Jokinen, P.; Korpiola, K.; Mahiout, A.

    2000-06-01

    The porosity of thermal sprayed coatings is usually a problem when coatings are used in wet corrosion application. The porosity allows media to penetrate to the surface of the base material. Corrosion spreads rapidly and the coating loses contact with the substrate and delaminates. This problem can be initiated by impregnating different polymers into the pores. An alternative approach has been tested in the present work to prevent corrosion of cemented carbide coated carbon steel in wet corrosion environments. Carbon steel substrates were coated with a thin film of electroless nickel (electroless nickel plating) and then HVOF (High-Velocity Oxygen Fuel) sprayed with cemented carbide. Reference specimens without electroless nickel were sprayed at the same time. The microhardness of the specimens was measured and the coating structure examined using optical microscopy and X-ray diffractometry (XRD). The bond between the layers and the base material was examined by means of a bend test. A salt chamber test was also performed for the specimens. The structure of the electroless nickel layer was crystalline as a result of the HVOF spraying. There were no cracks in the nickel layer, if the layer was about 20 µm thick. According to the results of the bend test, the adhesion between coatings and substrate was good, and there was no difference between the duplex-coated specimen and the reference specimen. A sample with a thin nickel layer under an HVOF sprayed cemented carbide did not exhibit corrosion after 8 h in the salt chamber test.

  18. Laser fusing of HVOF thermal sprayed alloy 625 on nickel-aluminum bronze

    SciTech Connect

    Brenna, R.T.; Pugh, J.L.; Denney, P.E.

    1994-12-31

    A preliminary study has been conducted to determine the feasibility of laser fusing alloy 625 onto nickel-aluminum-bronze base metal. Laser fusing was performed by melting a pre-coated surface of alloy 625 that had been applied by the high velocity oxyfuel (HVOF) thermal spray process. The laser fusing was successful in producing a metallurigical bond between alloy 625 and the substrate. Minor modification to the heat-affected zone of the base metal was observed by microhardness measurements, and defect-free interfaces were produced between alloy 625 and nickel-aluminum-bronze by the process. The laser is a high energy density source that can be used for precise thermal processing of materials including surface modification. Laser fusing is the full or partial melting of a coating material that has been previously applied in some fashion to the substrate. Thermal spray coating of nickel-aluminum-bronze material with alloy 625 was conducted at the David Taylor Research Center. Nickel-aluminum-bronze specimens 2 x 3-in. by 1/2-in. thick were coated with alloy 25 utilizing the HVOF equipment. Coating thicknesses of approximately 0.014-in. (0.3 mm) were produced for subsequent laser fusing experiments. A preliminary study has been conducted to determine the feasibility of laser fusing a HVOF thermal sprayed alloy 625 coating onto nickel-aluminum-bronze base metal. Conclusions of this investigation were as follows: (1) Laser fusing was successful in producing a metallurgical bond between HVOF thermal sprayed alloy 625 and the nickel-aluminum-bronze. (2) Only minor microstructural modification to the heat-affected zone of the base metal ws observed by microhardness measurements. (3) Defect-free interfaces were produced between thermal sprayed alloy 625 and nickel-aluminum-bronze by laser fusing.

  19. Replacement of Chromium Electroplating on Helicopter Dynamic Components Using HVOF Thermal Spray Technology

    DTIC Science & Technology

    2009-11-01

    axis robot arm in a soundproof booth, programmed and operated remotely. Most depots already use this type of booth for their existing plasma spray...installation requires: • A soundproof booth. Booths are typically 15 ft square, with a separate operator control room, an observation window, and a high...equipment in place as well as the appropriate air permits to cover operation of the HVOF systems. The equipment is installed in soundproof booths, with

  20. Influence of Bond Coat on HVOF-Sprayed Gradient Cermet Coating on Copper Alloy

    NASA Astrophysics Data System (ADS)

    Ke, Peng; Cai, Fei; Chen, Wanglin; Wang, Shuoyu; Ni, Zhenhang; Hu, Xiaohong; Li, Mingxi; Zhu, Guanghong; Zhang, Shihong

    2017-06-01

    Coatings are required on mold copper plates to prolong their service life through enhanced hardness, wear resistance, and oxidation resistance. In the present study, NiCr-30 wt.%Cr3C2 ceramic-metallic (cermet) layers were deposited by high velocity oxy-fuel (HVOF) spraying on different designed bond layers, including electroplated Ni, HVOF-sprayed NiCr, and double-decker Ni-NiCr. Annealing was also conducted on the gradient coating (GC) with NiCr bond layer to improve the wear resistance and adhesion strength. Coating microstructure was investigated by scanning electron microscopy and x-ray diffraction analysis. Mechanical properties including microhardness, wear resistance, and adhesion strength of the different coatings were evaluated systematically. The results show that the types of metallic bond layer and annealing process had a significant impact on the mechanical properties of the GCs. The GCs with electroplated Ni bond layer exhibited the highest adhesion strength (about 70 MPa). However, the GC with HVOF-sprayed NiCr bond layer exhibited better wear resistance. The wear resistance and adhesion strength of the coating with NiCr metallic bond layer were enhanced after annealing.

  1. Computational fluid dynamic analysis of a High-Velocity Oxygen-Fuel (HVOF) thermal spray torch

    SciTech Connect

    Hassan, B.; Oberkampf, W.L.; Neiser, R.A.; Roemer, T.J.

    1995-09-01

    The gas dynamics of a High-Velocity Oxygen-Fuel (HVOF) torch are analyzed using computational fluid dynamics (CFD) techniques. The thermal spray device analyzed is similar to a Metco Diamond Jet torch with powder feed. The injection nozzle is assumed to be axisymmetric with premixed fuel and oxygen fed from an annulus, and air cooling injected along the interior surface of the aircap. The aircap, a cronically converging nozzle, achieves choked flow conditions at the exit and a supersonic, under-expanded jet develops externally. Finite difference equations for mass, momentum, and energy conservation are solved for the gas dynamics. The combustion process is modeled using a single-step and a 12-step quasi-global finite-rate chemistry model with dissociation of the gas and a total of nine species. Turbulent flow inside the aircap and in the free-jet decay is modeled using a two-equation k-{epsilon} model. An iterative, implicit, finite volume numerical method is used to solve the gas dynamic equations inside and outside the torch . The CFD results are compared with recent experimental measurements of pressure inside the HVOF aircap. Comparisons are made for two flow rates of premixed fuel and oxygen and air cooling. This paper presents the first published comparisons of CFD predictions and experimental measurements for HVOF tbermal spraying.

  2. Optimization of the laser remelting process for HVOF-sprayed Stellite 6 wear resistant coatings

    NASA Astrophysics Data System (ADS)

    Ciubotariu, Costel-Relu; Frunzăverde, Doina; Mărginean, Gabriela; Șerban, Viorel-Aurel; Bîrdeanu, Aurel-Valentin

    2016-03-01

    Cobalt base alloys are used in all industrial areas due to their excellent wear resistance. Several studies have shown that Stellite 6 coatings are suitable not only for protection against sliding wear, but also in case of exposure to impact loading. In this respect, a possible application is the protection of hydropower plant components affected by cavitation. The main problem in connection with Stellite 6 is the deposition procedure of the protective layers, both welding and thermal spraying techniques requesting special measures in order to prevent the brittleness of the coating. In this study, Stellite 6 layers were HVOF thermally sprayed on a martensitic 13-4 stainless steel substrate, as usually used for hydraulic machinery components. In order to improve the microstructure of the HVOF-sprayed coatings and their adhesion to the substrate, laser remelting was applied, using a TRUMPF Laser type HL 124P LCU and different working parameters. The microstructure of the coatings, obtained for various remelting conditions, was evaluated by light microscopy, showing the optimal value of the pulse power, which provided a homogenous Stellite 6 layer with good adhesion to the substrate.

  3. Development of HVOF Sprayed Erosion/Oxidation Resistant Coatings for Composite Structural Components in Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Knight, R.; Ivosevic, M.; Twardowski, T. E.; Kalidindi, S. R.; Sutter, James K.; Kim, D. Y.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Thermally sprayed coatings are being studied and developed as methods of enabling lightweight composites to be used more extensively as structural components in propulsion applications in order to reduce costs and improve efficiency through weight reductions. The primary goal of this work is the development of functionally graded material [FGM] polymer/metal matrix composite coatings to provide improved erosion/oxidation resistance to polyimide-based polymer matrix composite [PMC] substrates. The goal is to grade the coating composition from pure polyimide, similar to the PMC substrate matrix on one side, to 100 % WC-Co on the other. Both step-wise and continuous gradation of the loading of the WC-Co reinforcing phase are being investigated. Details of the coating parameter development will be presented, specifically the high velocity oxy-fuel [HVOF] combustion spraying of pure PMR-11 matrix material and layers of various composition PMR-II/WC-Co blends onto steel and PMR-15 composite substrates. Results of the HVOF process optimization, microstructural characterization, and analysis will be presented. The sprayed coatings were evaluated using standard metallographic techniques - optical and scanning electron microscopy [SEM]. An SEM + electron dispersive spectroscopy [EDS] technique has also been used to confirm retention of the PMR-II component. Results of peel/butt adhesion testing to determine adhesion will also be presented.

  4. Development of HVOF Sprayed Erosion/Oxidation Resistant Coatings for Composite Structural Components in Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Ivosevic, M.; Twardowski, T.; Kalidindi, S.; Knight, R.; Sutter, J.; Kim, D. Y.

    1990-01-01

    Thermally sprayed coatings are being studied and developed as methods of enabling lightweight composites to be used more extensively as structural components in propulsion applications in order to reduce costs and improve efficiency through weight reductions. The primary goal of this work is the development of functionally graded material [FGM] polymer/metal matrix composite coatings to provide improved erosion/oxidation resistance to polyimide-based polymer matrix composite [PMC] substrates. The goal is to grade the coating composition from pure polyimide, similar to the PMC substrate matrix on one side, to 100% WC-Co on the other. Both step-wise and continuous gradation of the loading of the WC-Co reinforcing phase are being investigated, Details of the coating parameter development will be presented, specifically the high velocity oxy-fuel [HVOF] combustion spraying of pure PMR-I1 matrix material and layers of various composition PMR-II/WC-Co blends onto steel and PMR-15 composite substrates. Results of the HVOF process optimization, microstructural characterization, and analysis will be presented. The sprayed coatings were evaluated using standard metallographic techniques - optical and scanning electron microscopy [SEMI. An SEM + electron dispersive spectroscopy [EDS] technique has also been used to confirm retention of the PMR-I1 component. Results of peel/butt adhesion testing to determine adhesion will also be presented.

  5. Bactericidal Effects of HVOF-Sprayed Nanostructured TiO2 on Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Jeffery, B.; Peppler, M.; Lima, R. S.; McDonald, A.

    2010-01-01

    Titanium dioxide (TiO2) has been shown to exhibit photocatalytic bactericidal activity. This preliminary study focused on examining the photocatalytic activity of high-velocity oxy-fuel (HVOF) sprayed nanostructured TiO2 coatings to kill Pseudomonas aeruginosa. The surfaces of the nanostructured TiO2 coatings were lightly polished before addition of the bacterial solution. Plates of P. aeruginosa were grown, and then suspended in a phosphate buffer saline (PBS) solution. The concentration of bacteria used was determined by a photo-spectrometer, which measured the amount of light absorbed by the bacteria-filled solution. This solution was diluted and pipetted onto the coating, which was exposed to white light in 30-min intervals, up to 120 min. It was found that on polished HVOF-sprayed coatings exposed to white light, 24% of the bacteria were killed after exposure for 120 min. On stainless steel controls, approximately 6% of the bacteria were not recovered. These preliminary results show that thermal-sprayed nanostructured TiO2 coatings exhibited photocatalytic bactericidal activity with P. aeruginosa.

  6. Iron-Based Amorphous Coatings Produced by HVOF Thermal Spray Processing-Coating Structure and Properties

    SciTech Connect

    Beardsley, M B

    2008-03-26

    The feasibility to coat large SNF/HLW containers with a structurally amorphous material (SAM) was demonstrated on sub-scale models fabricated from Type 316L stainless steel. The sub-scale model were coated with SAM 1651 material using kerosene high velocity oxygen fuel (HVOF) torch to thicknesses ranging from 1 mm to 2 mm. The process parameters such as standoff distance, oxygen flow, and kerosene flow, were optimized in order to improve the corrosion properties of the coatings. Testing in an electrochemical cell and long-term exposure to a salt spray environment were used to guide the selection of process parameters.

  7. Characterization and High-Temperature Erosion Behaviour of HVOF Thermal Spray Cermet Coatings

    NASA Astrophysics Data System (ADS)

    Kumar, Pardeep; Sidhu, Buta Singh

    2016-01-01

    High-velocity oxygen fuel (HVOF) thermal spray, carbide-cermet-based coatings are usually employed in high-temperature erosive and erosive-corrosive environments. Extensive literature is available on high-temperature erosion performance of HVOF coatings under moderate to low particle flux and velocities for application in boiler tubes. This research work presents the characterization and high-temperature erosion behaviour of Cr3C2-25NiCr and WC-10Co-4Cr HVOF-sprayed coatings. Coatings were formulated on the substrate steel of type AISI 304, commonly used for the fabrication of pulverized coal burner nozzles (PCBN). Erosion testing was carried out in high-temperature air-jet erosion tester after simulating the conditions akin to that prevailing in PCBN in the boiler furnace. The coatings were tested for erosion behaviour at different angles and temperatures by freezing other test parameters. Brittle erosion behaviour was depicted in erosion testing, and the coatings couldn't restrain the erodent attacks to protect the substrate. High particle velocity and high particle flux were attributed to be the reasons of extensive erosive weight loss of the coatings. The surface morphology of the eroded specimens was analysed from back-scattered electron images to depict the probable mechanism of material removal. The coatings were characterized with optical microscopy, SEM-EDS analysis, XRD analysis, micro-hardness testing, porosity measurements, surface roughness testing and bond strength testing. The work was undertaken to investigate the performance of the selected coatings in highly erosive environment, so as to envisage their application in PCBNs for protection against material degradation. The coatings could only sustain in oblique impact erosion at room temperature and depleted fully under all other conditions.

  8. Hot Corrosion Behavior of HVOF Sprayed Coatings on ASTM SA213-T11 Steel

    NASA Astrophysics Data System (ADS)

    Sidhu, H. S.; Sidhu, B. S.; Prakash, S.

    2007-09-01

    Cr3C2-NiCr, NiCr, WC-Co and Stellite-6 alloy coatings were sprayed on ASTM SA213-T11 steel using the HVOF process. Liquid petroleum gas was used as the fuel gas. Hot corrosion studies were conducted on the uncoated as well as HVOF sprayed specimens after exposure to molten salt at 900 °C under cyclic conditions. The thermo-gravimetric technique was used to establish the kinetics of corrosion. XRD, SEM/EDAX and EPMA techniques were used to analyze the corrosion products. All these overlay coatings showed a better resistance to hot corrosion as compared to that of uncoated steel. NiCr Coating was found to be most protective followed by the Cr3C2-NiCr coating. WC-Co coating was least effective to protect the substrate steel. It is concluded that the formation of Cr2O3, NiO, NiCr2O4, and CoO in the coatings may contribute to the development of a better hot-corrosion resistance. The uncoated steel suffered corrosion in the form of intense spalling and peeling of the scale, which may be due to the formation of unprotective Fe2O3 oxide scale.

  9. Microstructure and Properties of HVOF-Sprayed Ni-50Cr Coatings

    SciTech Connect

    Joel A. Simpson; Terry C. Totemeier; Richard N. Wright

    2006-06-01

    Thermal spray coatings represent a potential cost-effective means of protecting structural components in advanced fossil energy systems. Previous work at the INL has focused on relationships between thermal spray processing conditions, structure, and properties in alumina- and silica-forming coatings, namely Fe3Al, FeAl, and Mo-Si-B alloys. This paper describes the preparation and characterization of chromia-forming Ni-50%Cr coatings, an alloy similar to the INCOCLAD 671 cladding, which has shown excellent performance in the Niles Plant service tests. The structure and properties of Ni-50Cr coatings are similar to other HVOF-sprayed metallic coatings: a typical lamellar microstructure is observed with essentially no porosity and little oxide. The microhardness and compressive residual stress both increase with increased spray particle velocity. Corrosion tests were performed on a variety of free-standing coatings (removed from the substrate, wrought Fe3Al alloy, and Grade 91 steel in a simulated coal combustion gas (N2-10%CO-5%CO2-2%H2O-0.12%H2S) and gas-slag environments (same gas, with iron sulfide powder in contact with the coating surface). The coatings tested included Fe3Al, FeAl, and Ni-50Cr alloys sprayed at different velocities. In these tests the iron aluminides in wrought and coating form showed the best performance, with Ni-50Cr coatings slightly worse; the Grade 91 steel was severely attacked.

  10. Relationships between spray parameters, microstructures and ultrasonic cavitation erosion behavior of HVOF sprayed Fe-based amorphous/nanocrystalline coatings.

    PubMed

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Zhang, Jianfeng; Shi, Wei; Zheng, Yugui

    2017-11-01

    Fe-based amorphous/nanocrystalline coatings were prepared on the AISI 321 steel substrate by the high-velocity oxygen-fuel (HVOF) thermal spraying technology. The effect of selected parameters (oxygen flow, kerosene flow and spray distance) on the cavitation erosion resistance (denoted as Rc) of the coating were investigated by using the Taguchi method. Statistical tools such as design of experiments (DOE), signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were used to meet the expected objective. It was concluded that the kerosene flow had greater influence on the Rc of the coating and followed by the spray distance and the oxygen flow, respectively. The optimum spray parameters (OSP) were 963L/min for the oxygen flow, 28L/h for the kerosene flow, and 330mm for the spray distance. The Rc of the coating increased with the increase of hardness or the decrease of porosity, and the hardness had a greater influence on Rc than the porosity. The Fe-based coating deposited under the OSP exhibited the best cavitation erosion resistance in distilled water. The cracks initiated at the edge of the pores and the interfaces between the un-melted or half-melted particles, and finally leaded to the delamination of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Quality optimization of thermally sprayed coatings produced by the JP-5000 (HVOF) gun using mathematical modeling

    NASA Technical Reports Server (NTRS)

    Tawfik, Hazem

    1994-01-01

    Currently, thermal barrier coatings (TBC) of gas-turbine blades and similar applications have centered around the use of zirconia as a protective coating for high thermal applications. The advantages of zirconia include low thermal conductivity and good thermal shock resistance. Thermally sprayed tungsten carbide hardface coatings are used for a wide range of applications spanning both the aerospace and other industrial markets. Major aircraft engine manufacturers and repair facilities use hardface coatings for original engine manufacture (OEM), as well as in the overhaul of critical engine components. The principle function of these coatings is to resist severe wear environments for such wear mechanisms as abrasion, adhesion, fretting, and erosion. The (JP-5000) thermal spray gun is the most advanced in the High Velocity Oxygen Fuel (HVOF) systems. Recently, it has received considerable attention because of its relative low cost and its production of quality coatings that challenge the very successful but yet very expensive Vacuum Plasma Spraying (VPS) system. The quality of thermal spray coatings is enhanced as porosity, oxidation, residual stress, and surface roughness are reduced or minimized. Higher densification, interfacial bonding strength, hardness and wear resistance of coating are desirable features for quality improvement.

  12. Sliding Wear Properties of HVOF Thermally Sprayed Nylon-11 and Nylon-11/Ceramic Composites on Steel

    NASA Astrophysics Data System (ADS)

    Jackson, L.; Ivosevic, M.; Knight, R.; Cairncross, R. A.

    2007-12-01

    Polymer and polymer/ceramic composite coatings were produced by ball-milling 60 μm Nylon-11 together with nominal 10 vol.% of nano and multiscale ceramic reinforcements and by HVOF spraying these composite feedstocks onto steel substrates to produce semicrystalline micron and nanoscale reinforced polymer matrix composites. Room temperature dry sliding wear performance of pure Nylon-11, Nylon-11 reinforced with 7 nm silica, and multiscale Nylon-11/silica composite coatings incorporating 7-40 nm and 10 μm ceramic particles were characterized using a pin-on-disk tribometer. Coefficient of friction and wear rate were determined as a function of applied load and coating composition. Surface profilometry and scanning electron microscopy were used to characterize and analyze the coatings and wear scars. The pure Nylon-11 coating experienced less wear than the composites due to the occurrence of two additional wear mechanisms: abrasive and fatigue wear.

  13. Thermal interaction between WC-Co coating and steel substrate in process of HVOF spraying

    SciTech Connect

    Guilemany, J.M.; Sobolev, V.V.; Nutting, J.; Dong, Z.; Calero, J.A. . Metalurgia Fisica-Ciencia de Materials)

    1994-10-01

    The WC-Co powders can be used to produce good adhesive and wear resistant HVOF thermal spray coatings on steel and light alloys substrates. In order to understand the properties of this kind of coating, the phases which are present in the coatings and structure changes during post heat treatments have been investigated. Although the coating properties depend very much on the structure developed in the substrate-coating interfacial region it has not been yet investigated in detail. The present study is devoted to the experimental and theoretical analysis of this interfacial region. The structure characterization has been performed mainly through the use of transmission electron microscopy. To provide a theoretical investigation a realistic prediction model of the process has been developed and on its base the mathematical simulation of the substrate-coating thermal interaction has been undertaken.

  14. A Study of Cr3C2-Based HVOF- and HVAF-Sprayed Coatings: Microstructure and Carbide Retention

    NASA Astrophysics Data System (ADS)

    Matikainen, V.; Bolelli, G.; Koivuluoto, H.; Honkanen, M.; Vippola, M.; Lusvarghi, L.; Vuoristo, P.

    2017-06-01

    The research on high-velocity air-fuel (HVAF)-sprayed Cr3C2-based materials has mostly focused on conventional Cr3C2-25NiCr composition. In this paper, two alternative compositions (Cr3C2-50NiCrMoNb and Cr3C2-37WC-18NiCoCrFe) were sprayed with high-velocity oxy-fuel (HVOF) and HVAF spray processes to evaluate the material behavior during spraying and to provide characterization of the microstructures and mechanical properties of the coatings. For comparison, coatings from the Cr3C2-25NiCr composition were sprayed with both processes. Spray diagnostics were carried out to obtain average particle velocity and temperature for each material and process combinations. The measured average in-flight particle data were 1800 °C and 700 m/s for HVOF process, and 1450 °C and 900 m/s for HVAF process. Characterization of the coating microstructures was carried out by scanning electron microscopy and X-ray diffraction. In addition, the carbon content of the feedstock powders and sprayed coatings was measured with carbon analyzer. The results show that carbide rebounding or selective deposition of particles with higher metal matrix content is the dominating reason for carbide loss during HVAF spraying, while carbide dissolution is an additional source for the HVOF spraying. Higher particle velocities and controlled temperature measured for the HVAF process produced dense coatings with improved toughness and more homogenous coating structure.

  15. A Study of Cr3C2-Based HVOF- and HVAF-Sprayed Coatings: Microstructure and Carbide Retention

    NASA Astrophysics Data System (ADS)

    Matikainen, V.; Bolelli, G.; Koivuluoto, H.; Honkanen, M.; Vippola, M.; Lusvarghi, L.; Vuoristo, P.

    2017-08-01

    The research on high-velocity air-fuel (HVAF)-sprayed Cr3C2-based materials has mostly focused on conventional Cr3C2-25NiCr composition. In this paper, two alternative compositions (Cr3C2-50NiCrMoNb and Cr3C2-37WC-18NiCoCrFe) were sprayed with high-velocity oxy-fuel (HVOF) and HVAF spray processes to evaluate the material behavior during spraying and to provide characterization of the microstructures and mechanical properties of the coatings. For comparison, coatings from the Cr3C2-25NiCr composition were sprayed with both processes. Spray diagnostics were carried out to obtain average particle velocity and temperature for each material and process combinations. The measured average in-flight particle data were 1800 °C and 700 m/s for HVOF process, and 1450 °C and 900 m/s for HVAF process. Characterization of the coating microstructures was carried out by scanning electron microscopy and X-ray diffraction. In addition, the carbon content of the feedstock powders and sprayed coatings was measured with carbon analyzer. The results show that carbide rebounding or selective deposition of particles with higher metal matrix content is the dominating reason for carbide loss during HVAF spraying, while carbide dissolution is an additional source for the HVOF spraying. Higher particle velocities and controlled temperature measured for the HVAF process produced dense coatings with improved toughness and more homogenous coating structure.

  16. Self-sharpening-effect of nickel-diamond coatings sprayed by HVOF

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Brinkhoff, A.; Schaak, C.; Zajaczkowski, J.

    2017-03-01

    The durability of stone working and drilling tools is an increasingly significant requirement in industrial applications. These tools are mainly produced by brazing diamond metal matrix composites inserts to the tool body. These inserts are produced by sintering diamonds and metal powder (e.g. nickel). If the wear is too high, the diamonds will break out of the metal matrix and other diamonds will be uncovered. This effect is called self-sharpening. But diamonds are difficult to handle because of their thermal sensitivity. Due to their high thermal influence, manufacturing costs, and complicate route of manufacturing (first sintering, then brazing), there is a great need for alternative production methods for such tools. One alternative to produce wear-resistant and self-sharpening coatings are thermal spray processes as examined in this paper. An advantage of thermal spray processes is their smaller thermal influence on the diamond, due to the short dwelling time in the flame. To reduce the thermal influence during spraying, nickel coated diamonds were used in the HVOF-process (high velocity oxygen fuel process). The wear resistance was subsequently investigated by means of a standardized ball-on-disc test. Furthermore, a SEM (scanning electron microscope) was used to gain information about the wear-mechanism and the self-sharpening effect of the coating.

  17. Analysis of a High Velocity Oxygen-Fuel (HVOF) thermal spray torch. Part 1, Numerical formulation

    SciTech Connect

    Oberkampf, W.L.; Talpallikar, M.

    1994-01-01

    The fluid and particle dynamics of a High Velocity Oxygen-Fuel (HVOF) torch are analyzed using computational fluid dynamic (CFD) techniques. The thermal spray device analyzed is similar to a Metco Diamond Jet torch with powder injection. The spray nozzle is axisymmetric with powder injection on the centerline, premixed fuel and oxygen fed from an annulus, and air cooling injected along the interior surface of the aircap. Choked flow conditions occur at the exit of the aircap and a supersonic, under-expanded jet develops externally. The CFD simulation assumes three injection streams (solid metal particles with argon as a carrier gas, premixed oxygen/fuel, and air) inside the aircap and solves the combusting two-phase flow until the external spray stream decays to sonic conditions. The numerical formulation solves the mass, momentum, and energy transfer for both the gas and particle phase and strongly couples each phase. The combustion process is modeled using approximate equilibrium chemistry with dissociation of the gas with a total of nine species. Melting and re-solidification of the metal panicles is modeled as a lumped-mass system. Turbulent flow is modeled by a two equation k-{epsilon} turbulence model, including compressibility effects on turbulent dissipation. A time iterative, implicit, finite volume numerical method is used to solve the partial differential equations. A companion paper [10] presents the results of the numerical simulation and gives a detailed discussion of the gas and panicle dynamics.

  18. Characterization of High Temp Thermal Sprays for Engine Applications

    DTIC Science & Technology

    2003-11-19

    Inconel 901) • Two Temperatures (300 °F, 750 °F) • One Thickness (0.010 inches) • Four Coatings – HVOF: WC-Co17; Tribaloy-400; Ni,Cr – PS : WC-Co17...Acoustic Emission Completed 7/03 – Adhesion Completed 9/03 3 Program Overview • Any relative performance differences between HVOF/ PS processes with...400 WC-Co17 – Plasma Spray • Tribaloy 400 WC-Co17 4 Fatigue • Directly compare EHC to HVOF and PS coatings • Specimen Details – Sprayed Shoulder to

  19. Fireside Corrosion Behavior of HVOF and Plasma-Sprayed Coatings in Advanced Coal/Biomass Co-Fired Power Plants

    NASA Astrophysics Data System (ADS)

    Hussain, T.; Dudziak, T.; Simms, N. J.; Nicholls, J. R.

    2013-06-01

    This article presents a systematic evaluation of coatings for advanced fossil fuel plants and addresses fireside corrosion in coal/biomass-derived flue gases. A selection of four candidate coatings: alloy 625, NiCr, FeCrAl and NiCrAlY were deposited onto superheaters/reheaters alloy (T91) using high-velocity oxy-fuel (HVOF) and plasma spraying. A series of laboratory-based fireside corrosion exposures were carried out on these coated samples in furnaces under controlled atmosphere for 1000 h at 650 °C. The tests were carried out using the "deposit-recoat" test method to simulate the environment that was anticipated from air-firing 20 wt.% cereal co-product mixed with a UK coal. The exposures were carried out using a deposit containing Na2SO4, K2SO4, and Fe2O3 to produce alkali-iron tri-sulfates, which had been identified as the principal cause of fireside corrosion on superheaters/reheaters in pulverized coal-fired power plants. The exposed samples were examined in an ESEM with EDX analysis to characterize the damage. Pre- and post-exposure dimensional metrologies were used to quantify the metal damage in terms of metal loss distributions. The thermally sprayed coatings suffered significant corrosion attack from a combination of aggressive combustion gases and deposit mixtures. In this study, all the four plasma-sprayed coatings studied performed better than the HVOF-sprayed coatings because of a lower level of porosity. NiCr was found to be the best performing coating material with a median metal loss of ~87 μm (HVOF sprayed) and ~13 μm (plasma sprayed). In general, the median metal damage for coatings had the following ranking (in the descending order: most to the least damage): NiCrAlY > alloy 625 > FeCrAl > NiCr.

  20. Manufacturing and Properties of High-Velocity Oxygen Fuel (HVOF)-Sprayed FeVCrC Coatings

    NASA Astrophysics Data System (ADS)

    Sassatelli, Paolo; Bolelli, Giovanni; Lusvarghi, Luca; Manfredini, Tiziano; Rigon, Rinaldo

    2016-10-01

    This paper studies the microstructure, sliding wear behavior and corrosion resistance of high-velocity oxygen fuel (HVOF)-sprayed FeVCrC-based coatings. Various process parameters were tested to evaluate their effects on the coating properties, which were also compared to those of HVOF-sprayed NiCrBSi and Stellite-6 coatings. The Fe alloy coatings are composed of flattened splats, originating from molten droplets and consisting of a super-saturated solid solution, together with rounded particles, coming from partially unmolten material and containing V- and Fe-based carbide precipitates. All process parameters, apart from "extreme" settings with excess comburent in the flame, produce dense coatings, indicating that the feedstock powder is quite easily processable by HVOF. These coatings, with a microhardness of 650-750 HV0.3, exhibit wear rates of ≈2 × 10-6 mm3/(Nm) in ball-on-disk tests against sintered Al2O3 spheres. They perform far better than the reference coatings, and better than other Fe- and Ni-based alloy coatings tested in previous research. On the other hand, the corrosion resistance of the coating material (tested by electrochemical polarization in 0.1 M HCl solution) is quite low. Even in the absence of interconnected porosity, this results in extensive, selective damage to the Fe-based matrix. This coating material is therefore unadvisable for severely corrosive environments.

  1. Comparative High-Temperature Corrosion Behavior of Ni-20Cr Coatings on T22 Boiler Steel Produced by HVOF, D-Gun, and Cold Spraying

    NASA Astrophysics Data System (ADS)

    Kaushal, Gagandeep; Bala, Niraj; Kaur, Narinder; Singh, Harpreet; Prakash, Satya

    2014-01-01

    To protect materials from surface degradations such as wear, corrosion, and thermal flux, a wide variety of materials can be deposited on the materials by several spraying processes. This paper examines and compares the microstructure and high-temperature corrosion of Ni-20Cr coatings deposited on T22 boiler steel by high velocity oxy-fuel (HVOF), detonation gun spray, and cold spraying techniques. The coatings' microstructural features were characterized by means of XRD and FE-SEM/EDS analyses. Based upon the results of mass gain, XRD, and FE-SEM/EDS analyses it may be concluded that the Ni-20Cr coating sprayed by all the three techniques was effective in reducing the corrosion rate of the steel. Among the three coatings, D-gun spray coating proved to be better than HVOF-spray and cold-spray coatings.

  2. Wear behaviors of HVOF sprayed WC-12Co coatings by laser remelting under lubricated condition

    NASA Astrophysics Data System (ADS)

    Dejun, Kong; Tianyuan, Sheng

    2017-03-01

    A HVOF (high velocity oxygen fuel) sprayed WC-12Co coating was remelted with a CO2 laser. The surface-interface morphologies and phases were analyzed by means of SEM (scanning electron microscopy), and XRD (X-ray diffraction), respectively. The friction and wear behaviors of WC-12Co coating under the dry and lubricated conditions were investigated with a wear test. The morphologies and distributions of chemical elements on worn scar were analyzed with a SEM, and its configured EDS (energy diffusive spectrometer), respectively, and the effects of lubricated condition on COFs (coefficient of friction) and wear performance were also discussed. The results show that the adhesion between the coating and the substrate is stronger after laser remetling (LR), in which mechanical bonding, accompanying with metallurgical bonding, was found. At the load of 80 N, the average COF under the dry and lubricated friction conditions is 0.069, and 0.052, respectively, the latter lowers by 23.3% than the former, and the wear rate under the lubricated condition decreases by 302.3% than that under the dry condition. The wear mechanism under the dry and lubrication conditions is primarily composed of abrasive wear, cracking, and fatigue failure.

  3. Corrosion behavior of HVOF sprayed hard face coatings in alkaline-sulfide solution

    NASA Astrophysics Data System (ADS)

    Li, Shenhou; Guo, Zhixing; Xiong, Ji; Lei, Yong; Li, Yuxi; Tang, Jun; Liu, Junbo; Ye, Junliu

    2017-09-01

    The paper focuses on the corrosion behavior of high velocity oxygen fuel (HVOF) sprayed WC-17Co, WC-10Co-4Cr, Cr3C2-25NiCr coatings in alkaline-sulfide solution (S2-, 0.2 ml/L, pH = 10). Eighteen days of immersion test is carried out and corrosion rate analysis shows that the Cr3C2-NiCr coating of low porosity exhibits the best corrosion resistance. In alkaline-sulfide solutions, porosity, passive film and microgalvanic between hard phase and binder phase have significant effect on the corrosion behavior of coatings. The corrosion mainly occurs in binder phase from SEM, though WO3, WS2, Cr2S3 are detected in XPS. In WC-17Co coating, the binder phase Co transforms to Co oxides and serious corrosion can be observed in binder phase. WC-10Co-4Cr coatings suffer localized corrosion since galvanic corrosion occurs between locations with different solubilities of W in Co binder. Cr3C2-25NiCr coating shows slight corrosion with the formation of NiS/Ni2O3/Cr2O3from the binder and Cr2S3 from the hard phase. The results are verified by the polarization curves, which show the longest passive region and lowest Icorrosion of Cr3C2-25NiCr coating.

  4. Combined slurry and cavitation erosion resistance of HVOF spray coated SS 410 steel

    NASA Astrophysics Data System (ADS)

    Amarendra, H. J.; Prathap, M. S.; Karthik, S.; Abhishek, A. M.; Madhu surya, K. C.; Gujjar gowda, S.; Anilkumar, T.

    2016-09-01

    The hydro turbine materials surface is degraded due to the slurry erosion and cavitation. The solid particles carried by water impacting the material results in slurry erosion. The damage occurred due to slurry erosion is the concern, when considered individually. The erosion damage is observed to be severe when slurry erosion and cavitation are combined. The hydro turbine material, martensitic stainless (SS 410) is surface modified with 80Ni-Cr by High Velocity Oxy Fuel spray process. The coated material subjected to post thermal treatment at a temperature of 950 ° C, soaked at 1 h, 2 h and 3 h are subjected to combined slurry and cavitation erosion test. The cavitation is created by using Cavitation Inducers. The tests are conducted by using silica sand as the erodent with three different sizes of 150, 200 and 300 μm. The results are compared with the as-received specimen. The results confirmed the effect of heat treatment on the end results, as the coated thermal treated specimens showed better erosion resistance against the as-received specimen. The eroded specimens are characterized by Scanning Electron Microscope. The thermal treated HVOF coated specimens shown the better erosion resistance.

  5. High Temperature Oxidation Behavior of HVOF-sprayed Coatings for Use in Thixoextrusion Processes

    SciTech Connect

    Picas, J. A.; Punset, M.; Menargues, S.; Campillo, M.; Baile, M. T.; Forn, A.

    2011-05-04

    The dies used for the thixoextrusion of steels have to be capable of withstanding complex thermal and mechanical loads, while giving a sufficient wear resistance against abrasion and adhesion at very high temperatures. In order to improve the wear resistance and reduce the heating of the extrusion die it can be protected with a hard cermet coating. The purpose of this work is to study the high-temperature performance of CrC-CoNiCrAlY coating and explore the potential application of this coating to improve dies used in thixoextrusion processes. A two-layer 75CrC-25CoNiCrAlY coating with a CoNiCrAlY bond-coating was fabricated by the HVOF thermal spray process on a steel substrate. Coatings were heat-treated at a range of temperatures between 900 deg. C and 1100 deg. C. The microstructural characterization of the coatings before and after heat treatment was conducted by scanning electron microscopy (SEM) and an X-ray diffractometer (XRD). The mechanical properties of coatings were determined as a function of the temperature of heat treatment. The bond coat effect on the thermal shock resistance of CrC-CoNiCrAlY coating was analyzed.

  6. Corrosion Behavior of HVOF-Sprayed Fe-Based Alloy Coating in Various Solutions

    NASA Astrophysics Data System (ADS)

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Qin, Yujiao; Shi, Wei; Li, Gaiye

    2017-08-01

    A Fe-based amorphous/nanocrystalline coating was prepared by the high-velocity oxygen fuel (HVOF) spraying process. The coating was characterized by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. The corrosion resistances of the Fe-based coating and a reference electroplated hard chromium (EHC) coating were evaluated in a 3.5% NaCl solution, a 1 mol/L HCl solution and a 1 mol/L NaOH solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). All of the results indicated that the corrosion resistance of the Fe-based coating was superior to the resistance of the EHC coating in both the 3.5% NaCl solution and the 1 mol/L HCl solution due to the dense structure and fewer defects of the Fe-based coating. However, the corrosion resistance of the Fe-based coating was inferior to corrosion resistance of the EHC coating in the 1 mol/L NaOH solution. This could be ascribed to the drastic passivation of the EHC coating in an alkaline environment.

  7. The characteristics of alumina scales formed on HVOF-sprayed MCrAlY coatings[High Velocity Oxygen Fuel

    SciTech Connect

    Toma, D.; Brandl, W.; Koester, U.

    2000-02-01

    HVOF MCrAlY (M = Ni, Co) coatings were isothermally oxidized in synthetic air between 850 and 1050 C for times up to 167 hr. During thermal spraying, aluminum and yttrium oxidized to form a fine oxide dispersion. The HVOF MCrAlY coatings exhibited a microstructure similar to ODS alloys. The fine dispersion consisted of Al{sub 2}O{sub 3} and aluminum-yttrium oxides. The oxidation experiments showed that the oxidation rate of HVOF coatings was two times slower than the oxidation rate of VPS MCrAlY coatings. The oxidation mechanism changed mainly in the transient-stage (no metastable modification of Al{sub 2}O{sub 3} formed) and it was assumed that the oxide dispersion hindered diffusion of various elements from the bulk material during oxidation. The formation of the fine oxide dispersion also influenced the adherence of the oxide scale. The microstructures of the transient oxide scales were examined by X-ray diffraction (XRD) scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

  8. Cracking and Spalling Behavior of HVOF Thermally Sprayed WC-Co-Cr Coating in Bend and Axial Fatigue Tests

    NASA Astrophysics Data System (ADS)

    Gui, M.; Eybel, R.; Asselin, B.; Monerie-Moulin, F.

    2015-03-01

    In this work, WC-10Co-4Cr coating was sprayed by high-velocity oxygen fuel (HVOF) process on Almen strip and axial fatigue coupon. Three-point bend test was used to bend Almen strip coating specimens with tensile and compressive stress applied to the coating. Axial fatigue coating specimens were tested at a load stress of 1250 MPa and a stress ratio of R = -1. Process condition of Thermal spraying was found to have an effect on spalling performance of the coating in the fatigue test. The mechanism of cracking and spalling process in the coating was studied in bend and fatigue conditions. Based on deformation difference between the coating and the substrate, the factors, especially coating thickness, to impact the coating spalling behavior in axial fatigue test are discussed. HVOF-sprayed WC-10Co-4Cr coating matches the deformation of base substrate by cracking when tensile stress is applied in bend and fatigue tests because the coating has very limit deformation capability. In axial fatigue test of WC-10Co-4Cr coating specimen, the substrate works in a stress-to-strain manner; however the coating works in a strain-to-stress manner and is stressed due to the substrate deformation.

  9. Influence of HVOF sprayed WC/Co coatings on the high-cycle fatigue strength of mild steel

    SciTech Connect

    Steffens, H.D.; Wilden, J.; Nassenstein, K.; Moebus, S.

    1995-12-31

    HVOF thermally sprayed WC/Co coatings are applied onto components which are exposed to wear caused by abrasion, erosion, fretting and sliding. Beside wear attacks and static stresses in lots of cases alternating mechanical stresses caused by dynamic loads occur additionally. Therefore, the fatigue resistance of WC/Co 88/12 and WC/Co 83/17 coated specimens was investigated by high-cycle fatigue tests (HCF). The results of the fatigue tests were documented in statistically ascertained Woehler-diagrams (S-N-curves). Furthermore, the mechanisms of failure are discussed.

  10. Progress in fabrication of large magnetic sheilds by using extended YBCO thick films sprayed on stainless steel with the HVOF technique

    SciTech Connect

    Pavese, F.; Bergadano, E.; Ferri, D.

    1997-06-01

    Fabricating a full box-type magnetic shield, by spraying a thick film of commercial YBCO powder on stainless steel with the oxygen-fuel high-velocity technique (HVOF, also referred to as {open_quotes}continuous detonation spray{close_quotes} (CDS)), requires the solution of several specific problems since the design stage of the project. The design problems of this type of shield are examined and the results obtained in the early stages of the realization are discussed.

  11. Physicochemical Characteristics of Dust Particles in HVOF Spraying and Occupational Hazards: Case Study in a Chinese Company

    NASA Astrophysics Data System (ADS)

    Huang, Haihong; Li, Haijun; Li, Xinyu

    2016-06-01

    Dust particles generated in thermal spray process can cause serious health problems to the workers. Dust particles generated in high velocity oxy-fuel (HVOF) spraying WC-Co coatings were characterized in terms of mass concentrations, particle size distribution, micro morphologies, and composition. Results show that the highest instantaneous exposure concentration of dust particles in the investigated thermal spray workshop is 140 mg/m3 and the time-weighted average concentration is 34.2 mg/m3, which are approximately 8 and 4 times higher than the occupational exposure limits in China, respectively. The large dust particles above 10 μm in size present a unique morphology of polygonal or irregular block of crushed powder, and smaller dust particles mainly exist in the form of irregular or flocculent agglomerates. Some heavy metals, such as chromium, cobalt, and nickel, are also found in the air of the workshop and their concentrations are higher than the limits. Potential occupational hazards of the dust particles in the thermal spray process are further analyzed based on their characteristics and the workers' exposure to the nanoparticles is assessed using a control banding tool.

  12. Design Optimization of Liquid Fueled High Velocity Oxy- Fuel Thermal Spraying Technique for Durable Coating for Fossil Power Systems

    SciTech Connect

    Choudhuri, Ahsan; Love, Norman

    2016-11-04

    systems, there exists a lack of fundamental understanding of the effect of hardware characteristics and operating parameters on HVOF thermally sprayed coatings. Motivated by these issues, this study is devoted to investigate the effect of hardware characteristics (e.g. spraying distance) and operating parameters (e.g. combustion chamber pressure, equivalence ratio, and total gas flow rate) on HVOF sprayed coatings using Inconel 718 alloy. The current study provides extensive understanding of several key operating and process parameters to optimize the next generation of HVOF thermally sprayed coatings for high temperature and harsh environment applications. A facility was developed to support this endeavor in a safe and efficient way, including a HVOF thermal spray system with a Data Acquisition and Remote Controls system (DARCS). The coatings microstructure and morphology were examined using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Nanoindentation.

  13. High Power Diode Laser-Treated HP-HVOF and Twin Wire Arc-Sprayed Coatings for Fossil Fuel Power Plants

    NASA Astrophysics Data System (ADS)

    Mann, B. S.

    2013-08-01

    This article deals with high power diode laser (HPDL) surface modification of twin wire arc-sprayed (TWAS) and high pressure high velocity oxy-fuel (HP-HVOF) coatings to combat solid particle erosion occurring in fossil fuel power plants. To overcome solid particle impact wear above 673 K, Cr3C2-NiCr-, Cr3C2-CoNiCrAlY-, and WC-CrC-Ni-based HVOF coatings are used. WC-CoCr-based HVOF coatings are generally used below 673 K. Twin wire arc (TWA) spraying of Tafa 140 MXC and SHS 7170 cored wires is used for a wide range of applications for a temperature up to 1073 K. Laser surface modification of high chromium stainless steels for steam valve components and LPST blades is carried out regularly. TWA spraying using SHS 7170 cored wire, HP-HVOF coating using WC-CoCr powder, Ti6Al4V alloy, and high chromium stainless steels (X20Cr13, AISI 410, X10CrNiMoV1222, 13Cr4Ni, 17Cr4Ni) were selected in the present study. Using robotically controlled parameters, HPDL surface treatments of TWAS-coated high strength X10CrNiMoV1222 stainless steel and HP-HVOF-coated AISI 410 stainless steel samples were carried out and these were compared with HPDL-treated high chromium stainless steels and titanium alloy for high energy particle impact wear (HEPIW) resistance. The HPDL surface treatment of the coatings has improved the HEPIW resistance manifold. The improvement in HPDL-treated stainless steels and titanium alloys is marginal and it is not comparable with that of HPDL-treated coatings. These coatings were also compared with "as-sprayed" coatings for fracture toughness, microhardness, microstructure, and phase analyses. The HEPIW resistance has a strong relationship with the product of fracture toughness and microhardness of the HPDL-treated HP-HVOF and TWAS SHS 7170 coatings. This development opens up a possibility of using HPDL surface treatments in specialized areas where the problem of HEPIW is very severe. The HEPIW resistance of HPDL-treated high chromium stainless steels and

  14. Oxidation behavior of HVOF-sprayed nanostructured and CeO2-modified WC-12Co coatings

    NASA Astrophysics Data System (ADS)

    Xi, Naiyuan; Hang, Zongqiu; Liu, Yan; Chen, Hui; Zhang, Mingyue; Gao, Wei

    2017-07-01

    Two types of WC-12Co coatings with different modifications were deposited on steel substrates using high velocity oxygen fuel (HVOF) spraying. The coated samples were oxidized at 550∘C and 650∘C in ambient atmosphere. Oxidation mass gain was measured by electronic balance. Phase composition and microstructure evolution of both coatings after oxidation were conducted by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microhardness testing was performed before and after oxidation testing. The results showed that at 550∘C and 650∘C, the rare-earth modified WC-12Co coating has lower oxidation rates compared with the nanostructured WC-12Co coating. This might be due to the rare-earth modification coating reducing the porosity and oxygen diffusion in the coatings, therefore delaying the crack formation and propagation.

  15. Study of the HVOF Ni-Based Coatings' Corrosion Resistance Applied on Municipal Solid-Waste Incinerators

    NASA Astrophysics Data System (ADS)

    Guilemany, J. M.; Torrell, M.; Miguel, J. R.

    2008-06-01

    Oxidation of exchanger steel tubes causes important problems in Municipal Solid-Waste Incinerator (MSWI) plants. The present paper shows a possible solution for this problem through High-Velocity Oxygen Fuel (HVOF) thermal spray coatings. A comparative study was carried out between powder and wire Ni-based thermal spray coatings (with the same composition). These optimized coatings were compared based on their microstructure, wear properties (ASTM G99-90, ASTM G65-91), and erosion-corrosion (E-C) resistance. An E-C test designed in the Thermal Spray Centre was performed to reproduce the mechanisms that take place in a boiler. Studying the results of this test, the wire HVT Inconel coating sprayed by propylene appears to be the best alternative. A commercial bulk material with a composition similar to Ni-based coatings was tested to find the products of the oxidation reactions. The protective mechanisms of these materials were assessed after studying the results obtained for HVOF coatings and the bulk material where the presence of nickel and chromium oxides as a corrosion product can be seen. Kinetic evolution of the Ni-based coatings can be studied by thermogravimetric analysis. The protection that Inconel coatings give to the tube through the difference of the gain mass can be seen. Ni-based HVOF coatings by both spray conditions are a promising alternative to MSWI protection against chlorine environments, and their structures have a very important role.

  16. A Study on Wear Resistance of HVOF-Sprayed Ni-MoS2 Self-Lubricating Composite Coatings

    NASA Astrophysics Data System (ADS)

    Liu, Y. L.; Jeng, M. C.; Hwang, J. R.; Chang, C. H.

    2015-02-01

    Composite coating techniques are becoming increasingly popular owing to their peculiar performances. In this study, the wear resistance of thermally sprayed Ni-MoS2 composite coatings on an AISI 1020 steel substrate was investigated. Ni-MoS2 composite powder (size: 60-90 μm) containing 25 wt.% of dispersed MoS2 was prepared by electroless plating. Ni-MoS2 composite coatings were then prepared by HVOF thermal spraying. The coatings were characterized by structural, surface morphological, and compositional analyses by means of microhardness tests, SEM/EDS, XRD, and ICP-AES. For the evaluation of their anti-wear properties, the composites were subjected to ball-on-disk dry wear tests based on the ASTM G99 standard at room temperature. Experimental results showed that some of the MoS2 content dispersed in the Ni-based composite coating burnt away during the high-temperature spraying process, thereby reducing the MoS2 concentration in the coating. In the wear test, the weight loss in the Ni-MoS2 composite coating was minimal under a low load (<15 N) but increased rapidly with increasing load (>30 N). The average wear rate of the coatings was found to be ~1/40 times that of a Ni coating, showing that the wear resistance of the composite coatings was significantly improved by MoS2 addition.

  17. Nano-Borides and Silicide Dispersed Composite Coating on AISI 304 Stainless Steel by Laser-Assisted HVOF Spray Deposition

    NASA Astrophysics Data System (ADS)

    Sharma, Prashant; Majumdar, Jyotsna Dutta

    2014-10-01

    The study concerned a detailed microstructural investigation of nano-borides (Cr2B and Ni3B) and nano-silicide (Ni2Si) dispersed γ-nickel composite coating on AISI 304 stainless steel by HVOF spray deposition of the NiCrBSi precursor powder and subsequent laser surface melting. A continuous wave diode laser with an applied power of 3 kW and scan speed of 20 mm/s in argon shroud was employed. The characterization of the surface in terms of microstructure, microtexture, phases, and composition were carried out and compared with the as-coated (high-velocity oxy-fuel sprayed) surface. Laser surface melting led to homogenization and refinement of microstructures with the formation of few nano-silicides of nickel along with nano-borides of nickel and chromium (Ni3B, Cr2B, and Cr2B3). A detailed microtexture analysis showed the presence of no specific texture in the as-sprayed and laser-melted surface of Cr2B and Ni3B phases. The average microhardness was improved to 750-900 VHN as compared to 250 VHN of the as-received substrate. Laser surface melting improved the microhardness further to as high as 1400 VHN due to refinement of microstructure and the presence of silicides.

  18. Cold Spray Deposition of Freestanding Inconel Samples and Comparative Analysis with Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Bagherifard, Sara; Roscioli, Gianluca; Zuccoli, Maria Vittoria; Hadi, Mehdi; D'Elia, Gaetano; Demir, Ali Gökhan; Previtali, Barbara; Kondás, Ján; Guagliano, Mario

    2017-10-01

    Cold spray offers the possibility of obtaining almost zero-porosity buildups with no theoretical limit to the thickness. Moreover, cold spray can eliminate particle melting, evaporation, crystallization, grain growth, unwanted oxidation, undesirable phases and thermally induced tensile residual stresses. Such characteristics can boost its potential to be used as an additive manufacturing technique. Indeed, deposition via cold spray is recently finding its path toward fabrication of freeform components since it can address the common challenges of powder-bed additive manufacturing techniques including major size constraints, deposition rate limitations and high process temperature. Herein, we prepared nickel-based superalloy Inconel 718 samples with cold spray technique and compared them with similar samples fabricated by selective laser melting method. The samples fabricated using both methods were characterized in terms of mechanical strength, microstructural and porosity characteristics, Vickers microhardness and residual stresses distribution. Different heat treatment cycles were applied to the cold-sprayed samples in order to enhance their mechanical characteristics. The obtained data confirm that cold spray technique can be used as a complementary additive manufacturing method for fabrication of high-quality freestanding components where higher deposition rate, larger final size and lower fabrication temperatures are desired.

  19. MoB/CoCr Cermet Coatings by HVOF Spraying against Erosion by Molten Al-Zn Alloy

    NASA Astrophysics Data System (ADS)

    Mizuno, Hiroaki; Kitamura, Junya

    2007-09-01

    MoB/CoCr, a novel cermet material for thermal spraying, with high durability in molten alloys has been developed to utilize for aluminum die-casting parts, and for hot continuous dipping rolls in Zn and Al-Zn plating lines. The durability of the MoB/CoCr coatings prepared by high velocity oxy-fuel (HVOF) spraying has been investigated using a molten-metal immersion tester. The tests revealed that the MoB/CoCr coating has much higher durability without dissolution in the molten Al-45wt.%Zn alloy. Little change of crystal structure, mainly composed of double borides of CoMoB and CoMo2B2, is observed after the immersion test, suggesting that the double borides have much higher durability. Using undercoat is effective to reduce the influence of large difference in thermal expansion between the MoB/CoCr topcoat and substrate of stainless steel of AISI 316L, widely used for the hot continuous dipping rolls. Optimized thickness combinations of topcoat and undercoat are necessary to obtain intrinsic performance of low reactive MoB/CoCr against the molten Al-45wt.%Zn alloy.

  20. Electrochemical Corrosion of HVOF-Sprayed NiCoCrAlY Coatings in CO2-Saturated Brine

    NASA Astrophysics Data System (ADS)

    Ruiz-Luna, H.; Porcayo-Calderon, J.; Alvarado-Orozco, J. M.; García-Herrera, J. E.; Martinez-Gomez, L.; Trápaga-Martínez, L. G.; Muñoz-Saldaña, J.

    2016-10-01

    The effect of pre-oxidation treatment and surface preparation of optimized NiCoCrAlY coatings deposited by high-velocity oxygen fuel (HVOF) spraying and exposed to a low-temperature corrosive environment is reported herein. Coatings with two surface finish conditions (as-sprayed and ground) were heat treated under two different oxygen partial pressures (air and argon). The electrochemical corrosion behavior was evaluated in CO2-saturated brine via potentiodynamic polarization, polarization resistance, and electrochemical impedance measurements. The results show that the grinding process and pre-oxidation treatment in argon enhanced growth and formation of α-Al2O3 scale. The potentiodynamic polarization results show that both pre-oxidation and surface treatment had a positive influence on the corrosion resistance of the coating. The reduction of the porosity and the formation of a dense, uniform, and adherent oxide scale through pre-oxidation treatment led to an increase of the corrosion resistance due to a decrease in active sites and blocking of diffusion of reactive species into the coating. However, according to the results, complete transformation from metastable alumina phases to α-Al2O3 in addition to formation and growth of dense α-Al2O3 is required to ensure full protection of the coating and base material over long periods.

  1. HVOF sprayed WC-CoCr coatings on aluminum: tensile and tribological properties

    NASA Astrophysics Data System (ADS)

    Koutsomichalis, A.; Vardavoulias, M.; Vaxevanidis, N.

    2017-02-01

    This paper provides a comprehensive assessment of the tensile and sliding wear behaviour of WC-10Co4Cr agglomerated and sintered powder deposited on aluminum by Hyper Velocity Oxy-Fuel (HVOF) process. Microstructural analysis (SEM) identified grains of tungsten carbide (WC) in the metal matrix of the cobalt-chromium (Co-Cr). A transformation of the WC in the W2C phase was observed and decomposition of WC in the metal matrix. The HVOF WC-Co-Cr coating was found to decrease tensile strength of the aluminum substrate. Transverse cracks were observed to initiate on the coating surface, increasing rapidly with the increase in tensile strain and stopped on the coating-substrate interface causing decohesion. Tribological properties were examined using the pin-on-disk method under various loads. The friction coefficient rose abruptly at the start-up phase and stabilized at almost the same sliding distance independently of the applied load. Both the friction coefficient and the wear volume were found to increase with increasing applied load. Study of the wear mechanisms revealed surface micro-cracking and fragmentation of flattened coating layers with subsequent gradual pull out of the carbide particles.

  2. Analytical methods to characterize heterogeneous raw material for thermal spray process: cored wire Inconel 625

    NASA Astrophysics Data System (ADS)

    Lindner, T.; Bonebeau, S.; Drehmann, R.; Grund, T.; Pawlowski, L.; Lampke, T.

    2016-03-01

    In wire arc spraying, the raw material needs to exhibit sufficient formability and ductility in order to be processed. By using an electrically conductive, metallic sheath, it is also possible to handle non-conductive and/or brittle materials such as ceramics. In comparison to massive wire, a cored wire has a heterogeneous material distribution. Due to this fact and the complex thermodynamic processes during wire arc spraying, it is very difficult to predict the resulting chemical composition in the coating with sufficient accuracy. An Inconel 625 cored wire was used to investigate this issue. In a comparative study, the analytical results of the raw material were compared to arc sprayed coatings and droplets, which were remelted in an arc furnace under argon atmosphere. Energy-dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF) analysis were used to determine the chemical composition. The phase determination was performed by X-ray diffraction (XRD). The results were related to the manufacturer specifications and evaluated in respect to differences in the chemical composition. The comparison between the feedstock powder, the remelted droplets and the thermally sprayed coatings allows to evaluate the influence of the processing methods on the resulting chemical and phase composition.

  3. Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

    NASA Astrophysics Data System (ADS)

    Kumar, R. K.; Kamaraj, M.; Seetharamu, S.; Pramod, T.; Sampathkumaran, P.

    2016-08-01

    The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.

  4. Oxidation behavior of nanostructured cobalt nickel chromium aluminum yttrium and nickel cobalt chromium aluminum yttrium sprayed by HVOF

    NASA Astrophysics Data System (ADS)

    Mercier, Dominic

    In recent years, much development has been made in the world of nanotechnologies. Hence, nanomaterials, which possess unique characteristics and excellent mechanical properties, are now being used in innovative and advanced applications. Despite the incredible potential of nanomaterials, their use is still at an embryonic stage as a result of the difficulty to mass-produce them. Among the potentially viable application remains the fabrication of nanostructured powders to produce high temperature oxidation resistance coatings. Nanostructured coatings were obtained by thermally spraying cryomilled CoNiCrAlY and NiCoCrAlY feedstock using the HVOF technique. It was found that the milling process used to prepare the powder significantly altered the microstructure of the alloy. In addition to achieving grain size refinement, significant aluminum segregation at grain boundaries was observed. Upon oxidation experiments up to 96 hours in static air at 1000°C an oxide scale composed of an adherent and dense alpha-Al2O3 inner layer with a top layer of fast growing oxides such as NiO, Cr2O3, CoAl2O4 and NiAl2O4 evolved from the coatings. It was found that the formation of a two-layer scale could be prevented through surface grinding prior to oxidation. Moreover, the comparison of the oxidation results of the powders and those of the coatings revealed that the spraying process has a considerable influence on the oxidation behavior of MCrAlYs attributable to the formation of oxide seeds during the spraying process.

  5. Investigations on the Behavior of HVOF and Cold Sprayed Ni-20Cr Coating on T22 Boiler Steel in Actual Boiler Environment

    NASA Astrophysics Data System (ADS)

    Bala, Niraj; Singh, Harpreet; Prakash, Satya; Karthikeyan, J.

    2012-01-01

    High temperature corrosion accompanied by erosion is a severe problem, which may result in premature failure of the boiler tubes. One countermeasure to overcome this problem is the use of thermal spray protective coatings. In the current investigation high velocity oxy-fuel (HVOF) and cold spray processes have been used to deposit commercial Ni-20Cr powder on T22 boiler steel. To evaluate the performance of the coatings in actual conditions the bare as well as the coated steels were subjected to cyclic exposures, in the superheater zone of a coal fired boiler for 15 cycles. The weight change and thickness loss data were used to establish kinetics of the erosion-corrosion. X-ray diffraction, surface and cross-sectional field emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) and x-ray mapping techniques were used to analyse the as-sprayed and corroded specimens. The HVOF sprayed coating performed better than its cold sprayed counterpart in actual boiler environment.

  6. Assessment of Abrasive Wear of Nanostructured WC-Co and Fe-Based Coatings Applied by HP-HVOF, Flame, and Wire Arc Spray

    NASA Astrophysics Data System (ADS)

    Lima, C. R. C.; Libardi, R.; Camargo, F.; Fals, H. C.; Ferraresi, V. A.

    2014-10-01

    Thermal spray processes have been widely used to minimize losses caused by wear mechanisms. Sprayed deposits using conventional wire and powder materials have been long solving tribological problems in engineering equipment. More recently, the option for new different technologies and consumables like nanostructured powder materials and nanocomposite cored wires have expanded the possibilities for technical solutions. Cored wire technology allows the use of compositions that cannot be drawn into wire form like carbides in metallic matrix and high-temperature materials, thus, intensifying the use of spraying processes with low operating cost to demanding wear and corrosion applications. The objective of this work was to study the mechanical characteristics and wear performance of coatings obtained by Flame, Wire Arc, and HVOF spraying using selected nanostructured WC10Co4Cr, WC12Co, and Fe-based 140 MXC powder and wire materials. Abrasive wear performance of the coatings was determinate following the ASTM G-65 standard. Based on the results, a higher abrasive wear resistance was found for the HVOF-sprayed WC10Co4Cr nanostructured coating.

  7. Spallation Resistant HVOF Coatings

    DTIC Science & Technology

    2012-08-30

    In Phase I, 14 different HVOF powder chemistries where sprayed and tested using the Praxair JP8000 spray system. Criteria for selection was that...Of these 14 chemistries, 4 where found to be top performers to be used in Phase II testing.  A Design Of Experiment (DOE) was performed on...following stress levels (or until spallation occurred)  190ksi  210ksi  230ksi  Initial testing with WC-Co top coat on all of the duplex

  8. Formation Mechanisms, Structure, and Properties of HVOF-Sprayed WC-CoCr Coatings: An Approach Toward Process Maps

    NASA Astrophysics Data System (ADS)

    Varis, T.; Suhonen, T.; Ghabchi, A.; Valarezo, A.; Sampath, S.; Liu, X.; Hannula, S.-P.

    2014-08-01

    Our study focuses on understanding the damage tolerance and performance reliability of WC-CoCr coatings. In this paper, the formation of HVOF-sprayed tungsten carbide-based cermet coatings is studied through an integrated strategy: First-order process maps are created by using online-diagnostics to assess particle states in relation to process conditions. Coating properties such as hardness, wear resistance, elastic modulus, residual stress, and fracture toughness are discussed with a goal to establish a linkage between properties and particle characteristics via second-order process maps. A strong influence of particle state on the mechanical properties, wear resistance, and residual stress stage of the coating was observed. Within the used processing window (particle temperature ranged from 1687 to 1831 °C and particle velocity from 577 to 621 m/s), the coating hardness varied from 1021 to 1507 HV and modulus from 257 to 322 GPa. The variation in coating mechanical state is suggested to relate to the microstructural changes arising from carbide dissolution, which affects the properties of the matrix and, on the other hand, cohesive properties of the lamella. The complete tracking of the coating particle state and its linking to mechanical properties and residual stresses enables coating design with desired properties.

  9. The effect of spraying parameters on micro-structural properties of WC-12%Co coating deposited on copper substrate by HVOF process

    SciTech Connect

    Sathwara, Nishit; Jariwala, C. Chauhan, N.; Raole, P. M.; Basa, D. K.

    2015-08-28

    High Velocity Oxy-Fuel (HVOF) thermal sprayed coatingmade from Tungsten Carbide (WC) isconsidered as one of the most durable materials as wear resistance for industrial applications at room temperature. WC coating offers high wear resistance due to its high hardness and tough matrix imparts. The coating properties strongly depend on thermal spray processing parameters, surface preparation and surface finish. In this investigation, the effect of variousHVOF process parameters was studied on WC coating properties. The WC-12%Co coating was produced on Copper substrate. Prior to coating, theCopper substrate surface was prepared by grit blasting. WC-12%Co coatings were deposited on Coppersubstrates with varying process parameters such as Oxygen gas pressure, Air pressure, and spraying distance. Microstructure of coating was examined using Scanning Electron Microscope (SEM) and characterization of phasespresentin the coating was examined by X-Ray Diffraction (XRD). Microhardness of all coatingswas measured by VickerMicrohardness tester. At low Oxygen Pressure(10.00 bar), high Air pressure (7bar) and short nozzle to substrate distance of 170mm, best coating adhesion and porosity less structure isachieved on Coppersubstrate.

  10. The Wear Behavior of HVOF Sprayed Near-Nanostructured WC-17%Ni(80/20)Cr Coatings in Dry and Slurry Wear Conditions

    NASA Astrophysics Data System (ADS)

    Ben Mahmud, Tarek A.; Atieh, Anas M.; Khan, Tahir I.

    2017-07-01

    The ability to deposit nanostructured feedstock by using high-velocity oxygen-fuel (HVOF) spray offers potential improvements in coating hardness, wear resistance and toughness for applications in the oil sands industry. In this study, the wear behavior of a near-nanostructured coating was compared under dry and slurry abrasive wear test using an uncoated AISI-1018 low-carbon steel substrate as a reference. The coating microstructures were analyzed in the as-sprayed, dry and slurry test conditions using scanning electron microscopy, x-ray diffraction and microhardness measurements. Wear behavior of the steel and coating surfaces were assessed using a pin-on-plate wear test under various loads. The results showed that a coating could be successfully deposited using the HVOF spraying technique and with retention of the near-nanosized WC dispersion within the coating structure. The wear rate under dry test conditions was greater for the steel and coating compared to tests performed under slurry conditions. Examination of the wear tracks revealed that the wear mechanism was different for the two test conditions. Wear in the dry test condition resulted from 2-body abrasion, while 3-body abrasion dominated wear in slurry conditions. The latter showed lower wear rates due to a lubricating effect of the oil.

  11. Mechanical property changes in HVOF sprayed nano-structured WC-17wt.%Ni(80/20)Cr coating with varying substrate roughness

    NASA Astrophysics Data System (ADS)

    Ben Mahmud, Tarek A.; Saha, Gobinda C.; Khan, Tahir I.

    2014-06-01

    Thermally sprayed coatings developed by use of high velocity oxy-fuel (HVOF) process are known for their superior wear characteristics. In many industrial applications, new parts as well as repaired and refurbished parts coated with WC-Co microstructured coatings have shown enhanced erosion-corrosion and abrasive resistant properties when compared with other surface modification technologies such as chrome replacement, fusion welding, and cladding. This research has been further directed towards the development of HVOF technique to deposit dense nanostructured ceramic-metallic composites. The mechanism of plastic deformation, which determines the strength and ductility of materials, in nanostructured materials are different, thereby leading to novel mechanical properties. Various parameters can influence these properties, but the substrate surface preparation by grit blasting before thermal spraying is one critical parameter. The grit blasting process generates a surface roughness, which ensures mechanical anchoring between the coating and the substrate surface. In this work, the sliding wear behavior and microhardness of WC-17wt.%Ni(80/20)Cr cermet coatings deposited onto carbon steel substrates are examined as a function of three different surface roughness values under different loads. The results show that as-prepared surface with different blasting profiles have a direct influence on the surface roughness and wear performance of the coatings. The sliding wear resistance of the coatings increased as the substrate surface roughness increased. The wear depth decreased with increasing surface roughness.

  12. Development and Application of HVOF Sprayed Spinel Protective Coating for SOFC Interconnects

    NASA Astrophysics Data System (ADS)

    Thomann, O.; Pihlatie, M.; Rautanen, M.; Himanen, O.; Lagerbom, J.; Mäkinen, M.; Varis, T.; Suhonen, T.; Kiviaho, J.

    2013-06-01

    Protective coatings are needed for metallic interconnects used in solid oxide fuel cell (SOFC) stacks to prevent excessive high-temperature oxidation and evaporation of chromium species. These phenomena affect the lifetime of the stacks by increasing the area-specific resistance (ASR) and poisoning of the cathode. Protective MnCo2O4 and MnCo1.8Fe0.2O4 coatings were applied on ferritic steel interconnect material (Crofer 22 APU) by high velocity oxy fuel spraying. The substrate-coating systems were tested in long-term exposure tests to investigate their high-temperature oxidation behavior. Additionally, the ASRs were measured at 700 °C for 1000 h. Finally, a real coated interconnect was used in a SOFC single-cell stack for 6000 h. Post-mortem analysis was carried out with scanning electron microscopy. The deposited coatings reduced significantly the oxidation of the metal, exhibited low and stable ASR and reduced effectively the migration of chromium.

  13. Effect of Load on Friction-Wear Behavior of HVOF-Sprayed WC-12Co Coatings

    NASA Astrophysics Data System (ADS)

    Yifu, Jin; Weicheng, Kong; Tianyuan, Sheng; Ruihong, Zhang; Dejun, Kong

    2017-07-01

    A WC-12Co coating was sprayed on AISI H13 hot work mold steel using a high-velocity oxygen fuel. The morphologies, phase compositions, and distributions of chemical elements of the obtained coatings were analyzed using a field emission scanning electron microscope, x-ray diffraction, and energy-dispersive spectroscope (EDS), respectively. The friction-wear behaviors under different loads were investigated using a reciprocating wear tester; the morphologies and distributions of the chemical elements of worn tracks were analyzed using a SEM and its configured EDS, respectively. The results show the reunited grains of WC are held together by the Co binder; the primary phases of the coating are WC, Co, and a small amount of W2C and W, owing to the oxidation and decarburization of WC. Inter-diffusion of Fe and W between the coating and the substrate is shown, which indicates a good coating adhesion. The values of the average coefficient of friction under the loads of 40, 80, and 120 N are 0.29, 0.31, and 0.49, respectively. The WC grains are pulled out of the coating during the sliding wear test, but the coating maintains its integrity, suggesting that the coating is intact and continuously protects the substrate from wearing.

  14. Bond Strength of Multicomponent White Cast Iron Coatings Applied by HVOF Thermal Spray Process

    NASA Astrophysics Data System (ADS)

    Maranho, Ossimar; Rodrigues, Daniel; Boccalini, Mario; Sinatora, Amilton

    2009-12-01

    Multicomponent white cast iron is a new alloy that belongs to system Fe-C-Cr-W-Mo-V, and because of its excellent wear resistance it is used in the manufacture of hot rolling mills rolls. To date, this alloy has been processed by casting, powder metallurgy, and spray forming. The high-velocity oxyfuel process is now also considered for the manufacture of components with this alloy. The effects of substrate, preheating temperature, and coating thickness on bond strength of coatings have been determined. Substrates of AISI 1020 steel and of cast iron with preheating of 150 °C and at room temperature were used to apply coatings with 200 and 400 μm nominal thickness. The bond strength of coatings was measured with the pull-off test method and the failure mode by scanning electron microscopic analysis. Coatings with thickness of 200 μm and applied on substrates of AISI 1020 steel with preheating presented bond strength of 87 ± 4 MPa.

  15. Effect of ultrasonic cavitation erosion on corrosion behavior of high-velocity oxygen-fuel (HVOF) sprayed near-nanostructured WC-10Co-4Cr coating.

    PubMed

    Hong, Sheng; Wu, Yuping; Zhang, Jianfeng; Zheng, Yugui; Qin, Yujiao; Lin, Jinran

    2015-11-01

    The effect of ultrasonic cavitation erosion on electrochemical corrosion behavior of high-velocity oxygen-fuel (HVOF) sprayed near-nanostructured WC-10Co-4Cr coating in 3.5 wt.% NaCl solution, was investigated using free corrosion potential, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in comparison with stainless steel 1Cr18Ni9Ti. The results showed that cavitation erosion strongly enhanced the cathodic current density, shifted the free corrosion potential in the anodic direction, and reduced the magnitude of impedance of the coating. The impedance of the coating decreased more slowly under cavitation conditions than that of the stainless steel 1Cr18Ni9Ti, suggesting that corrosion behavior of the coating was less affected by cavitation erosion than that of the stainless steel.

  16. Mechanical and Tribological Properties of HVOF-Sprayed (Cr3C2-NiCr+Ni) Composite Coating on Ductile Cast Iron

    NASA Astrophysics Data System (ADS)

    Ksiazek, Marzanna; Boron, Lukasz; Radecka, Marta; Richert, Maria; Tchorz, Adam

    2016-08-01

    The aim of the investigations was to compare the microstructure, mechanical, and wear properties of Cr3C2-NiCr+Ni and Cr3C2-NiCr coatings deposited by HVOF technique (the high-velocity oxygen fuel spray process) on ductile cast iron. The effect of nickel particles added to the chromium carbide coating on mechanical and wear behavior in the system of Cr 3 C 2 -NiCr+Ni/ductile cast iron was analyzed in order to improve the lifetime of coated materials. The structure with particular emphasis of characteristic of the interface in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron was studied using the optical, scanning, and transmission electron microscopes, as well as the analysis of chemical and phase composition in microareas. Experimental results show that HVOF-sprayed Cr3C2-NiCr+Ni composite coating exhibits low porosity, high hardness, dense structure with large, partially molten Ni particles and very fine Cr3C2 and Cr7C3 particles embedded in NiCr alloy matrix, coming to the size of nanocrystalline. The results were discussed in reference to examination of bending strength considering cracking and delamination in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron as well as hardness and wear resistance of the coating. The composite structure of the coating provides the relatively good plasticity of the coating, which in turn has a positive effect on the adhesion of coating to the substrate and cohesion of the composite coating (Cr3C2-NiCr+Ni) in wear conditions.

  17. High-Temperature Exposure Studies of HVOF-Sprayed Cr3C2-25(NiCr)/(WC-Co) Coating

    NASA Astrophysics Data System (ADS)

    Singh, Harpreet; Kaur, Manpreet; Prakash, Satya

    2016-08-01

    In this research, development of Cr3C2-25(NiCr) + 25%(WC-Co) composite coating was done and investigated. Cr3C2-25(NiCr) + 25%(WC-Co) composite powder [designated as HP2 powder] was prepared by mechanical mixing of [75Cr3C2-25(NiCr)] and [88WC-12Co] powders in the ratio of 75:25 by weight. The blended powders were used as feedstock to deposit composite coating on ASTM SA213-T22 substrate using High Velocity Oxy-Fuel (HVOF) spray process. High-temperature oxidation/corrosion behavior of the bare and coated boiler steels was investigated at 700 °C for 50 cycles in air, as well as, in Na2SO4-82%Fe2(SO4)3 molten salt environment in the laboratory. Erosion-corrosion behavior was investigated in the actual boiler environment at 700 ± 10 °C under cyclic conditions for 1500 h. The weight-change technique was used to establish the kinetics of oxidation/corrosion/erosion-corrosion. X-ray diffraction, field emission-scanning electron microscopy/energy-dispersive spectroscopy (FE-SEM/EDS), and EDS elemental mapping techniques were used to analyze the exposed samples. The uncoated boiler steel suffered from a catastrophic degradation in the form of intense spalling of the scale in all the environments. The oxidation/corrosion/erosion-corrosion resistance of the HVOF-sprayed HP2 coating was found to be better in comparison with standalone Cr3C2-25(NiCr) coating. A simultaneous formation of protective phases might have contributed the best properties to the coating.

  18. Influence of cryomilling on the microstructural features in HVOF-sprayed NiCrAlY bond coats for thermal barrier coatings: Creation of a homogeneous distribution of nanoscale dispersoids

    NASA Astrophysics Data System (ADS)

    Ma, Kaka; Schoenung, Julie M.

    2010-10-01

    Previous research has revealed that thermal barrier coatings with cryomilled bond coats exhibit improved thermal cycling lifetime by growing a continuous and uniform oxide layer at a slower rate; yet the mechanism controlling the ultimate failure remains unclear. In an effort to provide a foundation for understanding the improved behavior, the influence of cryomilling on the microstructure of the NiCrAlY bond coat material is investigated in this article. Rather than focusing on the alumina scale formation, the microstructural features and their evolution within the high-velocity oxy-fuel (HVOF)-sprayed NiCrAlY bond coats themselves, prepared from conventional powder and cryomilled powder, were carefully compared through extensive scanning electron microscope/energy-dispersive X-ray spectroscopy characterization. In addition, the as-cryomilled NiCrAlY powder is characterized to provide evidence of the direct influence of cryomilling and to exclude the impact from the HVOF spraying. It is found that the essential change in microstructural features resulting from the cryomilling is the creation of a homogeneous distribution of ultrafine (nanoscale) Al-rich oxide/nitride dispersoids, which remain thermally stable even after exposure at 1100°C for 100 h. The TEM study on the as-cryomilled powder, prior to the HVOF spraying, indicates that some Al and Y-rich oxides are already present within the material as a direct result of the cryomilling process.

  19. Corrosion and Wear Studies of Cr3C2NiCr-HVOF Coatings Sprayed on AA7050 T7 Under Cooling

    NASA Astrophysics Data System (ADS)

    Magnani, M.; Suegama, P. H.; Espallargas, N.; Fugivara, C. S.; Dosta, S.; Guilemany, J. M.; Benedetti, A. V.

    2009-09-01

    In this work, cermet coatings were prepared by high-velocity oxygen-fuel (HVOF) technique using a Diamalloy 3007 powder. The influence of the spray parameters on corrosion, friction, and abrasive wear resistance was studied. The samples were obtained using the standard conditions (253 L/min of oxygen and 375 L/min of compressed air), higher oxygen flux (341 L/min), and higher carrier gas flux (500 L/min). The coatings were characterized using scanning electron microscopy (SEM), and x-ray diffraction (XRD). X-ray diffraction and SEM studies showed well-bounded coating/substrate interface, pores, metallic matrix, chromium oxides, carbides, and carbides dissolution into the matrix. In comparison with the standard condition, the sample prepared using higher oxygen flux showed the highest carbide dissolution because of the high temperature achieved in the spray process. When the carrier gas flux was increased, the sample showed denser structure because of the higher particle velocity. The friction and abrasive wear resistance of the coatings were studied using rubber wheel and ball-on-disk tests. All samples showed similar sliding and abrasive behavior, and all of them showed better performance than the aluminum alloy. The electrochemical behavior was evaluated using open-circuit potential ( E OC) measurements, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization curves. The coating prepared with higher carrier gas flux showed the highest corrosion resistance in 3.5% NaCl solution and probably no pitting attack to the substrate occurred even after around 26 h of test. Tests performed for longer immersion times showed that the total impedance values significantly decreased (6 and 4 times) for samples sprayed using standard and higher oxygen flux, and no great change for sample sprayed using higher carrier gas flux was observed. The last sample presents a corrosion resistance around 200 times higher than the others.

  20. Influence of Fine Powder Feedstock (-10 + 2 μm) on the HVOF Spraying Characteristics, Coating Morphology, and Properties of WC-CoCr 86-10-4

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Nebel, J.; Piotrowski, W.

    2013-03-01

    The use of fine feedstock powder can extend the feasibility and scope of HVOF coatings to new fields of applications. Especially for the purpose of near-net-shape coatings, these powders facilitate homogeneous layer morphologies, and smooth coating surfaces. However, the small particle sizes also lead to several challenges. One major issue is the in-flight behavior which is distinctly affected by the low mass and relatively large specific surface of the particles. In this paper, the in-flight and coating characteristics of WC-CoCr 86-10-4 (-10 + 2 μm) were investigated. It was determined that the fine powder feedstock shows a high sensitivity to the gas flow, velocity, and temperature of the spray jet. Because of their low mass inertia, their velocity, for example, is actually influenced by local pressure nodes (shock diamonds) in the supersonic flow. Additionally, the relatively large specific surface of the particles promotes partial overheating and degradation. Nevertheless, the morphological and mechanical properties of the sprayed layer are hardly affected. In fact, the coatings feature a superior surface roughness, porosity, hardness, and wear resistance.

  1. Synergistic effect of ultrasonic cavitation erosion and corrosion of WC-CoCr and FeCrSiBMn coatings prepared by HVOF spraying.

    PubMed

    Hong, Sheng; Wu, Yuping; Zhang, Jianfeng; Zheng, Yugui; Zheng, Yuan; Lin, Jinran

    2016-07-01

    The high-velocity oxygen-fuel (HVOF) spraying process was used to fabricate conventional WC-10Co-4Cr coatings and FeCrSiBMn amorphous/nanocrystalline coatings. The synergistic effect of cavitation erosion and corrosion of both coatings was investigated. The results showed that the WC-10Co-4Cr coating had better cavitation erosion-corrosion resistance than the FeCrSiBMn coating in 3.5 wt.% NaCl solution. After eroded for 30 h, the volume loss rate of the WC-10Co-4Cr coating was about 2/5 that of the FeCrSiBMn coating. In the total cumulative volume loss rate under cavitation erosion-corrosion condition, the pure cavitation erosion played a key role for both coatings, and the total contribution of pure corrosion and erosion-induced corrosion of the WC-10Co-4Cr coating was larger than that of the FeCrSiBMn coating. Mechanical effect was the main factor for cavitation erosion-corrosion behavior of both coatings.

  2. Characterization and Evaluation of Cyclic Hot Corrosion Resistance of Detonation-Gun Sprayed Ni-5Al Coatings on Inconel-718

    NASA Astrophysics Data System (ADS)

    Saladi, Sekar; Menghani, Jyoti V.; Prakash, Satya

    2015-06-01

    The high temperature hot corrosion behavior of bare and detonation-gun-sprayed Ni-5Al coatings on Ni-based superalloy Inconel-718 is comparatively discussed in the present study. Hot corrosion studies were carried out at 900 °C for 100 cycles in Na2SO4-60% V2O5 molten salt environment under cyclic heating and cooling conditions. The thermo-gravimetric technique was used to establish the kinetics of hot corrosion. X-ray diffraction, SEM/EDAX, and X-ray mapping techniques were used to analyze the hot corrosion products of bare and coated superalloys. The results indicate that Ni-5Al-coated superalloy showed very good hot corrosion resistance. The overall weight gain and parabolic rate constant of Ni-5Al-coated superalloy were less in comparison with the bare superalloy. The D-gun-sprayed Ni-5Al coating was found to be uniform, adherent, and dense in hot corrosion environment. The formation of nickel- and aluminum-rich oxide scale might have contributed for the better hot corrosion resistance of the coated superalloy.

  3. High temperature wear performance of HVOF-sprayed Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr hardmetal coatings

    NASA Astrophysics Data System (ADS)

    Zhou, Wuxi; Zhou, Kesong; Li, Yuxi; Deng, Chunming; Zeng, Keli

    2017-09-01

    A novel Cr3C2-WC-NiCoCrMo and commercial Cr3C2-NiCr thermal spray-grade powders with particle size of -45 + 15 μm were prepared by an agglomeration and sintering process. Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr coatings were deposited by high velocity oxygen fuel (HVOF) spraying. The fundamental properties of both coatings were evaluated and friction wear test against Al2O3 counterbodies of both coatings at high temperatures (450 °C, 550 °C, 650 °C) were carried out ball-on-disk high temperature tribometer. All specimens were characterized by optical microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and 3D non-contact surface mapping profiler. The results have shown that the Cr3C2-WC-NiCoCrMo coating exhibited lower porosity, higher micro-hardness compared to the Cr3C2-NiCr coating. The Cr3C2-WC-NiCoCrMo coating also exhibited better wear resistance and higher friction coefficient compared to the Cr3C2-NiCr coating when sliding against the Al2O3 counterpart. Wear rates of both coatings increased with raising temperature. Both coatings experienced abrasive wear; hard phase particles (WC and Cr3C2) with different sizes, distributed in the matrix phase, will effectively improve the resistance against wear at high temperatures.

  4. HVOF- and HVAF-Sprayed Cr3C2-NiCr Coatings Deposited from Feedstock Powders of Spherical Morphology: Microstructure Formation and High-Stress Abrasive Wear Resistance Up to 800 °C

    NASA Astrophysics Data System (ADS)

    Janka, L.; Norpoth, J.; Trache, R.; Thiele, S.; Berger, L.-M.

    2017-10-01

    Chromium carbide-based coatings are commonly applied to protect surfaces against wear at high temperatures. This work discusses the influence of feedstock powder and spray torch selection on the microstructure and high-stress abrasion resistance of thermally sprayed Cr3C2-NiCr coatings. Four commercial feedstock powders with spherical morphology and different microstructures were deposited by different high-velocity spray processes, namely third-generation gas- and liquid-fueled HVOF torches and by the latest generation HVAF torch. The microstructures of the coatings were studied in the as-sprayed state and after various heat treatments. The high-stress abrasion resistance of as-sprayed and heat-treated coatings was tested at room temperature and at 800 °C. The study reveals that the selection of the spray torch mainly affects the room temperature abrasion resistance of the as-sprayed coatings, which is due to differences in the embrittlement of the binder phase generated by carbide dissolution. At elevated temperatures, precipitation and growth of secondary carbides yields a fast equalization of the various coatings microstructures and wear properties.

  5. HVOF- and HVAF-Sprayed Cr3C2-NiCr Coatings Deposited from Feedstock Powders of Spherical Morphology: Microstructure Formation and High-Stress Abrasive Wear Resistance Up to 800 °C

    NASA Astrophysics Data System (ADS)

    Janka, L.; Norpoth, J.; Trache, R.; Thiele, S.; Berger, L.-M.

    2017-08-01

    Chromium carbide-based coatings are commonly applied to protect surfaces against wear at high temperatures. This work discusses the influence of feedstock powder and spray torch selection on the microstructure and high-stress abrasion resistance of thermally sprayed Cr3C2-NiCr coatings. Four commercial feedstock powders with spherical morphology and different microstructures were deposited by different high-velocity spray processes, namely third-generation gas- and liquid-fueled HVOF torches and by the latest generation HVAF torch. The microstructures of the coatings were studied in the as-sprayed state and after various heat treatments. The high-stress abrasion resistance of as-sprayed and heat-treated coatings was tested at room temperature and at 800 °C. The study reveals that the selection of the spray torch mainly affects the room temperature abrasion resistance of the as-sprayed coatings, which is due to differences in the embrittlement of the binder phase generated by carbide dissolution. At elevated temperatures, precipitation and growth of secondary carbides yields a fast equalization of the various coatings microstructures and wear properties.

  6. Mechanical Properties and Thermal Shock Resistance of HVOF Sprayed NiCrAlY Coatings Without and With Nano Ceria

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoguang; Chen, Shufen; Wang, You; Pan, Zhaoyi; Wang, Liang

    2012-09-01

    NiCrAlY coatings without and with 0.2 wt.% nano ceria were prepared by high velocity oxygen fuel spraying. The microstructure, mechanical properties, and thermal shock resistance of as-sprayed coatings were investigated. The results showed that in the as-sprayed coatings, the number of un-melted particles was reduced drastically, the microstructure was refined and compact due to the refinement of sprayable powders. Both the hardness and adhesive strength of the NiCrAlY increased due to the refinement of microstructure and the decrease of the defects, such as pores and oxides, after adding nano ceria. The thermal cycle life of NiCrAlY coatings was improved by 15% after adding 0.2 wt.% nano ceria, which is attributed to the low content of spinel NiCr2O4 and high content of Cr2O3 in the thermal cycling, the refined and compact microstructure, and increased interfacial boundary.

  7. Microstructure Evolution and Its Effect on the Wear Performance of HVOF-Sprayed Conventional WC-Co Coating

    NASA Astrophysics Data System (ADS)

    Fu, Dingfa; Xiong, Haoqi; Wang, Qun

    2016-10-01

    In this work, a conventional tungsten carbide 12% cobalt (WC-12Co) coating was deposited by using a liquid fuel JP-8000 high velocity oxyfuel spray system. The properties of the coating namely phase content, microstructure, hardness, porosity, and fracture toughness were examined. The microstructure evolution and its influence on the abrasive wear behavior of the coatings were evaluated in detail by in-situ scanning electron microscopy and a comprehensive model for decarburization of WC has been established using x-ray diffraction and transmission electron microscopy analyses.

  8. Computational analysis of a three-dimensional High-Velocity Oxygen-Fuel (HVOF) Thermal Spray torch

    SciTech Connect

    Hassan, B.; Lopez, A.R.; Oberkampf, W.L.

    1995-07-01

    An analysis of a High-Velocity Oxygen-Fuel Thermal Spray torch is presented using computational fluid dynamics (CFD). Three-dimensional CFD results are presented for a curved aircap used for coating interior surfaces such as engine cylinder bores. The device analyzed is similar to the Metco Diamond Jet Rotating Wire torch, but wire feed is not simulated. To the authors` knowledge, these are the first published 3-D results of a thermal spray device. The feed gases are injected through an axisymmetric nozzle into the curved aircap. Argon is injected through the center of the nozzle. Pre-mixed propylene and oxygen are introduced from an annulus in the nozzle, while cooling air is injected between the nozzle and the interior wall of the aircap. The combustion process is modeled assuming instantaneous chemistry. A standard, two-equation, K-{var_epsilon} turbulence model is employed for the turbulent flow field. An implicit, iterative, finite volume numerical technique is used to solve the coupled conservation of mass, momentum, and energy equations for the gas in a sequential manner. Flow fields inside and outside the aircap are presented and discussed.

  9. HVOF Thermal Spray TiC/TiB2 Coatings for AUSC Boiler/Turbine Components for Enhanced Corrosion Protection

    SciTech Connect

    Mondal, Kanchan; Koc, Rasit; Fan, Chinbay

    2016-12-07

    The high temperatures of operations still pose significant risk of degradation and fatigue from oxidizing, corroding and eroding environment. In addition to unused O2, water from combustion and SOx from the coal sulfur oxidation that result in highly corrosive environment, acid gases such as HCl and other sulfur compounds may also be present. These adverse effects are further accelerated due to the elevated temperatures. In addition, ash particulates and unburnt carbon and pyritic sulfur can cause erosion of the surface and thus loss of material. Unburnt carbon and pyritic sulfur may also cause localized reduction sites. Thus, fireside corrosion protection and steam oxidation protection alternatives to currently used Ni-Cr overlays need to be identified and evaluated. Titanium carbide (TiC) is a suitable alternative on account of the material features such as the high hardness, the high melting point, the high strength and the low density for the substitution or to be used in conjunction with NiCr for enhancing the fireside corrosion and erosion of the materials. Another alternative is the use of titanium boride as a coating for chemical stability required for long-term service and high erosion resistance over the state-of-the-art, high fracture toughness (K1C ~12 MPam1/2) and excellent corrosion resistance (kp~1.9X10-11 g2/cm4/s at 800°C in air). The overarching aim of the research endeavor was to synthesize oxidation, corrosion and wear resistant TiC and TiB2 coating powders, apply thermal spray coating on existing boiler materials and characterize the coated substrates for corrosion resistance for applications at high temperatures (500 -750 °C) and high pressures (~350 bars) using the HVOF process and to demonstrate the feasibility of these coating to be used in AUSC boilers and turbines.

  10. Microstructure and Properties of HVOF-Sprayed NiCrAlY Coatings Modified by Rare Earth

    NASA Astrophysics Data System (ADS)

    Chen, S. F.; Liu, S. Y.; Wang, Y.; Sun, X. G.; Zou, Z. W.; Li, X. W.; Wang, C. H.

    2014-06-01

    Rare earth (RE)-modified NiCrAlY powders were prepared by ultrasonic gas atomization and deposited on stainless steel substrate by high-velocity oxygen fuel spraying. The effects of the RE on the microstructure, properties, and thermal shock resistance of the NiCrAlY coatings were investigated. The results showed that the NiCrAlY powders were refined and distributed uniformly after adding RE, while the number of unmelted particles in the coatings was reduced. Moreover, the RE-modified coatings showed improved microhardness and distribution uniformity. The microhardness of the coating reached a maximum after adding 0.9 wt.% RE, being 34.4 % higher than that of coatings without RE. The adhesive strength increased and reached a maximum after adding 0.6 wt.% RE, being 18.8 % higher than that of coatings without RE. Excessive RE decreased the adhesive strength. The thermal cycle life of NiCrAlY coatings increased drastically with RE addition. The coating with 0.9 wt.% RE showed optimum thermal shock resistance, being 21.2 % higher than that of coatings without RE.

  11. Computational fluid dynamics analysis of a wire-feed, high-velocity oxygen-fuel (HVOF) thermal spray torch

    SciTech Connect

    Lopez, A.R.; Hassan, B.; Oberkampf, W.L.; Neiser, R.A.; Roemer, T.J.

    1996-09-01

    The fluid and particle dynamics of a High-Velocity Oxygen-Fuel Thermal Spray torch are analyzed using computational and experimental techniques. Three-dimensional Computational Fluid Dynamics (CFD) results are presented for a curved aircap used for coating interior surfaces such as engine cylinder bores. The device analyzed is similar to the Metco Diamond Jet Rotating Wire (DJRW) torch. The feed gases are injected through an axisymmetric nozzle into the curved aircap. Premixed propylene and oxygen are introduced from an annulus in the nozzle, while cooling air is injected between the nozzle and the interior wall of the aircap. The combustion process is modeled using a single-step finite-rate chemistry model with a total of 9 gas species which includes dissociation of combustion products. A continually-fed steel wire passes through the center of the nozzle and melting occurs at a conical tip near the exit of the aircap. Wire melting is simulated computationally by injecting liquid steel particles into the flow field near the tip of the wire. Experimental particle velocity measurements during wire feed were also taken using a Laser Two-Focus (L2F) velocimeter system. Flow fields inside and outside the aircap are presented and particle velocity predictions are compared with experimental measurements outside of the aircap.

  12. Desirability-Based Multi-Criteria Optimization of HVOF Spray Experiments to Manufacture Fine Structured Wear-Resistant 75Cr3C2-25(NiCr20) Coatings

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Vogli, E.; Baumann, I.; Kopp, G.; Weihs, C.

    2010-01-01

    Thermal spraying of fine feedstock powders allow the deposition of cermet coatings with significantly improved characteristics and is currently of great interest in science and industry. However, due to the high surface to volume ratio and the low specific weight, fine particles are not only difficult to spray but also show a poor flowability in the feeding process. In order to process fine powders reliably and to preserve the fine structure of the feedstock material in the final coating morphology, the use of novel thermal spray equipment as well as a thorough selection and optimization of the process parameters are fundamentally required. In this study, HVOF spray experiments have been conducted to manufacture fine structured, wear-resistant cermet coatings using fine 75Cr3C2-25(Ni20Cr) powders (-8 + 2 μm). Statistical design of experiments (DOE) has been utilized to identify the most relevant process parameters with their linear, quadratic and interaction effects using Plackett-Burman, Fractional-Factorial and Central Composite designs to model the deposition efficiency of the process and the majorly important coating properties: roughness, hardness and porosity. The concept of desirability functions and the desirability index have been applied to combine these response variables in order to find a process parameter combination that yields either optimum results for all responses, or at least the best possible compromise. Verification experiments in the so found optimum obtained very satisfying or even excellent results. The coatings featured an average microhardness of 1004 HV 0.1, a roughness Ra = 1.9 μm and a porosity of 1.7%. In addition, a high deposition efficiency of 71% could be obtained.

  13. A Study on the Cyclic Oxidation Behavior of Detonation-Gun-Sprayed Ni-5Al Coatings on Inconel-718 at 900 °C

    NASA Astrophysics Data System (ADS)

    Saladi, Sekar; Menghani, Jyoti; Prakash, Satya

    2014-12-01

    Cyclic oxidation behavior of detonation-gun-sprayed Ni-5Al coating on Inconel-718 is discussed in the present study. Oxidation studies were carried out on both bare and coated superalloy substrates in air at 900 °C for 100 cycles. The thermogravimetric technique was used to establish kinetics of oxidation. X-ray diffraction, FESEM/EDAX, and x-ray mapping techniques were used to analyze the oxidation products of bare and coated samples. The weight gain of bare superalloy was higher than the Ni-5Al-coated superalloy. Both bare and Ni-5Al-coated superalloys followed nearly parabolic oxidation behavior. The Ni-5Al coating was able to reduce the overall weight gain by 26.2% in comparison with bare superalloy in the given environment. The better oxidation resistance of Ni-5Al coating may be due the formation of protective oxides phases such as NiO, Al2O3, and NiAl2O4 on the oxidized coating and Cr2O3 at the coating-substrate interface. The Ni-5Al coatings obtained from detonation-gun-spraying process showed very little porosity and low surface roughness values.

  14. In-Service Evaluation of HVOF Coated Main Landing Gear on Navy P-3 Aircraft

    NASA Technical Reports Server (NTRS)

    Devereaux, jon L.; Forrest, Clint

    2008-01-01

    Due to the environmental and health concerns with Electroplated Hard Chrome (EHC), the Hard Chrome Alternatives Team (HCAT) has been working to provide an alternative wear coating for EHC. The US Navy selected Tungsten-Carbide Cobalt (WC- 17Co) High Velocity Oxy-Fuel (HVOF) thermal spray coating for this purpose and completed service evaluations on select aircraft components to support the HCAT charter in identifying an alternative wear coating for chrome plating. Other benefits of WC-Co thermal spray coatings over EHC are enhanced corrosion resistance, improved durability, and exceptional wear properties. As part of the HCAT charter and to evaluate HVOF coatings on operational Navy components, the P-3 aircraft was selected for a service evaluation to determine the coating durability as compared to chrome plating. In April 1999, a VP-30 P-3 aircraft was outfitted with a right-hand Main Landing Gear (MLG) shock strut coated with WCCo HYOF thermal spray applied to the piston barrel and four axle journals. The HVOF coating on the piston barrel and axle journals was applied by Southwest United Industries, Inc. This HVOF coated strut assembly has since completed 6,378 landings. Teardown analysis .for this WC-Co HVOF coated MLG asset is significant in assessing the durability of this wear coating in service relative to EHC and to substantiate Life Cycle Cost (LCC) data to support a retrograde transition from EHC to HVOF thermal spray coatings. Findings from this teardown analysis may also benefit future transitions to HVOF thermal spray coatings by identifying enhancements to finishing techniques, mating bearing and liner material improvements, improved seal materials, and improvements in HVOF coating selection.

  15. Role of Oxides and Porosity on High-Temperature Oxidation of Liquid-Fueled HVOF Thermal-Sprayed Ni50Cr Coatings

    NASA Astrophysics Data System (ADS)

    Song, B.; Bai, M.; Voisey, K. T.; Hussain, T.

    2017-02-01

    High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high-temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid-fueled high velocity oxy-fuel thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using oxygen content analysis, mercury intrusion porosimetry, scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Short-term air oxidation tests (4 h) of freestanding coatings (without boiler steel substrate) in a thermogravimetric analyzer at 700 °C were performed to obtain the kinetics of oxidation of the as-sprayed coating. Long-term air oxidation tests (100 h) of the coated substrates were performed at same temperature to obtain the oxidation products for further characterization in detail using SEM/EDX and XRD. In all samples, oxides of various morphologies developed on top of the Ni50Cr coatings. Cr2O3 was the main oxidation product on the surface of all three coatings. The coating with medium porosity and medium oxygen content has the best high-temperature oxidation performance in this study.

  16. Improved Protection Properties by Using Nanostructured Ceramic Powders for HVOF Coatings

    NASA Astrophysics Data System (ADS)

    Varis, T.; Knuuttila, J.; Turunen, E.; Leivo, J.; Silvonen, J.; Oksa, M.

    2007-12-01

    The potential of the high-velocity oxy-fuel (HVOF) thermal spray process for reduced porosity in coatings compared to those produced by other ambient thermal spray processes is well known. The ability to produce high-density ceramic coatings offers potential in high-performance applications in the field of wear, corrosion resistance, and dielectric coatings. However, due to operational limit of the HVOF process to effectively melt the ceramic particles, the process—structure relationship must be well optimized. It has been also demonstrated that benefits from HVOF ceramic coatings can be obtained only if particles are melted enough and good lamella adhesion is produced. One strategy to improve melting of ceramic particles in relative low-flame temperatures of HVOF process is to modify particle crystal structure and composition. In this paper the effect of the powder manufacturing method and the composition on deposition efficiency of spray process as well as on the mechanical properties of the HVOF sprayed are studied. Effect of fuel gas, hydrogen vs. propane, was also demonstrated. Studied materials were alumina-, chromia-, and titania-based agglomerated powders. Coating properties such as microstructure, hardness, abrasive wear resistance, and relative fracture toughness were compared to the coating manufactured by using conventional fused and crushed powders. It can be concluded that powder size distribution and microstructure should be optimized to fulfill process requirements very carefully to produce coatings with high deposition efficiency, dense structure, improved fracture toughness, and adhesion.

  17. High temperature intermetallic binders for HVOF carbides

    SciTech Connect

    Shaw, K.G.; Gruninger, M.F.; Jarosinski, W.J.

    1994-12-31

    Gas turbines technology has a long history of employing the desirable high temperature physical attributes of ceramic-metallic (cermet) materials. The most commonly used coatings incorporate combinations of WC-Co and Cr{sub 3}C{sub 2}-NiCr, which have also been successfully utilized in other non-turbine coating applications. Increased turbine operating temperatures and other high temperature service conditions have made apparent the attractive notion of increasing the temperature capability and corrosion resistance of these coatings. In this study the intermetallic binder NiAl has been used to replace the cobalt and NiCr constituents of conventional WC and Cr{sub 3}C{sub 2} cermet powders. The composite carbide thermal spray powders were fabricated for use in the HVOF coating process. The structure of HVOF deposited NiAl-carbide coatings are compared directly to the more familiar WC-Co and Cr{sub 3}C{sub 2}-NiCr coatings using X-ray diffraction, back-scattered electron imaging (BEI) and electron dispersive spectroscopy (EDS). Hardness variations with temperature are reported and compared between the NiAl and Co/NiCr binders.

  18. High-Power Diode Laser Surface Treated HVOF Coating to Combat High Energy Particle Impact Wear

    NASA Astrophysics Data System (ADS)

    Mann, B. S.; Arya, Vivek; Pant, B. K.

    2013-07-01

    High-velocity oxy-fuel (HVOF)-sprayed coatings have performed exceptionally well in low-energy particle impact wear and are accepted worldwide. However, their application for high-energy particle impact wear (HEPIW) requires a different approach and more efforts. HVOF-coating systems typically use WC-Co, WC-Co-Cr, WC-Ni-Cr, and FeCrAlY-Cr3C2 powders. WC-Co-Cr powders are preferred when there is a high demand for corrosion resistance. WC-10Co-4Cr coating powder has been selected in the current study. To improve coating properties such as microhardness, fracture toughness, and HEPIW resistance, a new approach of surface treatment with robotically controlled high-power diode laser (HPDL) is attempted. The robotically controlled HVOF-coating deposition and laser surface treatment were monitored using real-time diagnostic control. The HPDL-treated coating has been compared with "as-sprayed" HVOF coating for HEPIW resistance, fracture toughness, microhardness and microstructure. The coating characteristics and properties after laser surface treatment have improved many times compared with "as-sprayed" HVOF coating. This is due to the elimination of pores in the coating and formation of a metallurgical bond between coating and substrate. This new development opens up a possibility of using such laser treatments in specialized areas where HEPIW damages are acute. The fracture toughness and HEPIW resistance along with optical micrographs of HPDL-treated and untreated HVOF coatings are discussed and reported in this article. HEPIW resistance is observed to be proportional to the product of fracture toughness and microhardness of the HVOF coating.

  19. Hill AFB HVOF Implementation

    DTIC Science & Technology

    2007-01-23

    program • Review part function • Review stress level Design and manufacture tools/fixtures Prototype Spraying •Adjustments made as needed Final Spray...measurement •Conduct grind operation •Surface finish measurement •Conduct temper etch •Conduct Barkhausen Noise Inspection (BNI) Teamwork - Integrity

  20. Messier-Dowty/HVOF Implementation

    DTIC Science & Technology

    2008-02-27

    prefer to have ‘ one - stop shop’ taking care of all operations: - Nital etch, MPI, shot peen, HVOF, grind, inspection,cad plating, paint, etc… • Bare...rate Dedicate full-time resources to the assignment Preference for the one - stop shop concept 13 Direction / Reference / Date MESSIER-DOWTY

  1. Numerical simulation of gas and particle flow field characteristics in HVOF guns

    SciTech Connect

    Yang, X.; Eidelman, S.; Lottati, I.

    1995-12-31

    The particle flow field characteristics in an HVOF gun are examined using numerical simulation techniques. The authors consider the particle injection, acceleration, convection heat transfer, and particle barrel interaction processes in a TAFA JP-5000 HVOF gun. Details of particle trajectories and temperature history as a function of particle size and other parameters are simulated and analyzed. A parameter study is conducted for different particle size, particle injection direction, and particle velocity. The number of distinct particle injection regimes was predicted and analyzed. Particle velocity and temperature at the exit of the barrel are listed. Using numerical simulation, the injection condition can be designed as a function of the set of flow parameters as well as particle properties, including particle size and material properties, to optimize the thermal spray process. A companion paper by the same authors in this proceedings presents a comprehensive analysis of the gas flow conditions for the HVOF gun.

  2. Laser Surface Treatment of Stellite 6 Coating Deposited by HVOF on 316L Alloy

    NASA Astrophysics Data System (ADS)

    Shoja-Razavi, Reza

    2016-07-01

    This research aimed to study the effects of laser glazing treatment on microstructure, hardness, and oxidation behavior of Stellite 6 coating deposited by high velocity oxygen fuel (HVOF) spraying. The as-sprayed Stellite 6 coating (ST-HVOF) was subjected to single-pass and multiple-pass laser treatments to achieve the optimum glazing parameters. Microstructural characterizations were performed by x-ray diffractometry and field emission scanning electron microscopy equipped with energy-dispersive spectroscopy. Two-step optimization showed that laser treatment at the power of 200 W with a scan rate of 4 mm/s causes a surface layer with a thickness of 208 ± 32 µm to be remelted, while the underlying layers retain the original ST-HVOF coating structure. The obtained sample (ST-Glazing) exhibited a highly dense and uniform structure with an extremely low porosity of ~0.3%, much lower than that of ST-HVOF coating (2.3%). The average microhardness of ST-Glazing was measured to be 519 Hv0.3 indicating a 17% decrease compared to ST-HVOF (625 Hv0.3) due to the residual stress relief and dendrite coarsening from submicron size to ~3.4 µm after laser treatment. The lowest oxidation mass gain was obtained for ST-Glazing by 2 mg/cm2 after 8 cycles at 900 °C indicating 52 and 84% improvement in oxidation resistance in comparison to ST-HVOF and bare 316L steel substrates, respectively.

  3. Carbon nanotube reinforced aluminum nanocomposite via plasma and high velocity oxy-fuel spray forming.

    PubMed

    Laha, T; Liu, Y; Agarwal, A

    2007-02-01

    Free standing structures of hypereutectic aluminum-23 wt% silicon nanocomposite with multiwalled carbon nanotubes (MWCNT) reinforcement have been successfully fabricated by two different thermal spraying technique viz Plasma Spray Forming (PSF) and High Velocity Oxy-Fuel (HVOF) Spray Forming. Comparative microstructural and mechanical property evaluation of the two thermally spray formed nanocomposites has been carried out. Presence of nanosized grains in the Al-Si alloy matrix and physically intact and undamaged carbon nanotubes were observed in both the nanocomposites. Excellent interfacial bonding between Al alloy matrix and MWCNT was observed. The elastic modulus and hardness of HVOF sprayed nanocomposite is found to be higher than PSF sprayed composites.

  4. Method of producing thermally sprayed metallic coating

    DOEpatents

    Byrnes, Larry Edward; Kramer, Martin Stephen; Neiser, Richard A.

    2003-08-26

    The cylinder walls of light metal engine blocks are thermally spray coated with a ferrous-based coating using an HVOF device. A ferrous-based wire is fed to the HVOF device to locate a tip end of the wire in a high temperature zone of the device. Jet flows of oxygen and gaseous fuel are fed to the high temperature zone and are combusted to generate heat to melt the tip end. The oxygen is oversupplied in relation to the gaseous fuel. The excess oxygen reacts with and burns a fraction of the ferrous-based feed wire in an exothermic reaction to generate substantial supplemental heat to the HVOF device. The molten/combusted metal is sprayed by the device onto the walls of the cylinder by the jet flow of gases.

  5. Hot corrosion behavior of Ni based Inconel 617 and Inconel 738 superalloys

    NASA Astrophysics Data System (ADS)

    El-Awadi, G. A.; Abdel-Samad, S.; Elshazly, Ezzat S.

    2016-08-01

    Superalloys are extensively used at high temperature applications due to their good oxidation and corrosion resistance properties in addition to their high stability were made at high temperature. Experimental measurements of hot corrosion at high temperature of Inconel 617 and Inconel 738 superalloys. The experiments were carried out at temperatures 700 °C, 800 °C and 900 °C for different exposure times to up to 100 h. The corrosive media was NaCl and Na2SO4 sprayed on the specimens. Seven different specimens were used at each temperature. The corrosion process is endothermic and the spontaneity increased by increasing temperature. The activation energy was found to be Ea = 23.54 and Ea = 25.18 KJ/mol for Inconel 738 and Inconel 617 respectively. X-ray diffraction technique (XRD) was used to analyze the formed scale. The morphology of the specimen and scale were examined by scanning electron microscopy (SEM). The results show that the major corrosion products formed were NiCr2O4, and Co Cr2O4 spinles, in addition to Cr2O3.

  6. Characterization of WC-10Ni HVOF Coating for Carbon Steel Blade

    NASA Astrophysics Data System (ADS)

    Ahmad, N. A.; Kamdi, Z.; Mohamad, Z.; Omar, A. S.; Latif, N. Abdul; Tobi, A. L. Mohd

    2017-01-01

    High Velocity Oxy-Fuel, HVOF is a depositing methods of a material layer over a base metal or substrate with characteristics of high flame velocity and moderate temperature. Where, tungsten carbide, WC cermet HVOF coatings is widely used to protect machine components from wear and corrosion. The main purpose of this present paper is to characterize the WC-10Ni coating deposited by HVOF thermal spray onto a carbon steel blade. The morphology and chemical composition of the coating were characterized by Scanning Electron Microstructure (SEM), electron dispersive spectrometer (EDS), and X-ray diffraction (XRD). The hardness test was carried out by using Vickers micro-hardness tester with loads of 490.3 mN (HV0.05). From XRD results, no sharp nickel peak was identified and has been replaced by a hump which indicate the amorphous Ni. The major crystalline phases were compounds WC, W2C and metallic phase of W. The WC-10Ni coating shows high hardness with low porosity distribution.

  7. Hot Corrosion of Yttrium Stabilized Zirconia Coatings Deposited by Air Plasma Spray on a Nickel-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Vallejo, N. Diaz; Sanchez, O.; Caicedo, J. C.; Aperador, W.; Zambrano, G.

    In this research, the electrochemical impedance spectroscopy (EIS) and Tafel analysis were utilized to study the hot corrosion performance at 700∘C of air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) coatings with a NiCrAlY bond coat grown by high velocity oxygen fuel spraying (HVOF), deposited on an INCONEL 625 substrate, in contact with corrosive solids salts as vanadium pentoxide V2O5 and sodium sulfate Na2SO4. The EIS data were interpreted based on proposed equivalent electrical circuits using a suitable fitting procedure performed with Echem AnalystTM Software. Phase transformations and microstructural development were examined using X-ray diffraction (XRD), with Rietveld refinement for quantitative phase analysis, scanning electron microscopy (SEM) was used to determinate the coating morphology and corrosion products. The XRD analysis indicated that the reaction between sodium vanadate (NaVO3) and yttrium oxide (Y2O3) produces yttrium vanadate (YVO4) and leads to the transformation from tetragonal to monoclinic zirconia phase.

  8. HVOF-Deposited WCCoCr as Replacement for Hard Cr in Landing Gear Actuators

    NASA Astrophysics Data System (ADS)

    Agüero, A.; Camón, F.; García de Blas, J.; Del Hoyo, J. C.; Muelas, R.; Santaballa, A.; Ulargui, S.; Vallés, P.

    2011-12-01

    WCCoCr coatings deposited by HVOF can replace hard Cr on landing gear components. Powders with two different WC particle sizes (micro and nano-) and geometries have been employed to study the effects on the coating's properties. Moreover, coatings produced employing two sets of parameters resulting in high and low flame temperatures have been evaluated. Minor differences in microstructure and morphology were observed for the two powders employing the same spraying parameters, but the nano-sized powder exhibited a higher spraying efficiency. However, more significant microstructural changes result when the low- and high-energy spray parameters are used. Moreover, results of various tests which include adhesion, wear, salt fog corrosion resistance, liquid immersion, and axial fatigue strength, indicate that the coatings produced with high-energy flame are similar in behavior. On the other hand, the nanostructured low-energy flame coating exhibited a significantly lower salt fog corrosion resistance.

  9. Influence of the spray velocity on arc-sprayed coating structures

    NASA Astrophysics Data System (ADS)

    Steffens, H.-D.; Nassenstein, K.

    1999-09-01

    Thermal spray processes such as plasma spraying and HVOF have gained markets due to a steady process of development of materials and equipment. One disadvantage of thermal spray processes is that costs must be competitive compared to techniques such as PTA and electroplating. In order to reduce costs, the more economical spray processes like conventional wire flame spraying, as well as arc spraying, are becoming more popular. There are modern arc spray gun designs on the market that meet the requirements of modern coating properties, for example aviation overhaul applications as well as the processing of cored wires. Nevertheless, the physical basis of arc spraying is well known. The aim of the present investigation is to show how the influence of spray velocity (not particle velocity) affects coating structure with respect to arc spray parameters.

  10. A Comparative Study on Ni-Based Coatings Prepared by HVAF, HVOF, and APS Methods for Corrosion Protection Applications

    NASA Astrophysics Data System (ADS)

    Sadeghimeresht, E.; Markocsan, N.; Nylén, P.

    2016-12-01

    Selection of the thermal spray process is the most important step toward a proper coating solution for a given application as important coating characteristics such as adhesion and microstructure are highly dependent on it. In the present work, a process-microstructure-properties-performance correlation study was performed in order to figure out the main characteristics and corrosion performance of the coatings produced by different thermal spray techniques such as high-velocity air fuel (HVAF), high-velocity oxy fuel (HVOF), and atmospheric plasma spraying (APS). Previously optimized HVOF and APS process parameters were used to deposit Ni, NiCr, and NiAl coatings and compare with HVAF-sprayed coatings with randomly selected process parameters. As the HVAF process presented the best coating characteristics and corrosion behavior, few process parameters such as feed rate and standoff distance (SoD) were investigated to systematically optimize the HVAF coatings in terms of low porosity and high corrosion resistance. The Ni and NiAl coatings with lower porosity and better corrosion behavior were obtained at an average SoD of 300 mm and feed rate of 150 g/min. The NiCr coating sprayed at a SoD of 250 mm and feed rate of 75 g/min showed the highest corrosion resistance among all investigated samples.

  11. Wear and impact resistance of HVOF sprayedceramic matrix composites coating

    NASA Astrophysics Data System (ADS)

    Prawara, B.; Martides, E.; Priyono, B.; Ardy, H.; Rikardo, N.

    2016-02-01

    Ceramic coating has the mechanical properties of high hardness and it is well known for application on wear resistance, but on the other hand the resistance to impact load is low. Therefore its use is limited to applications that have no impact loading. The aim of this research was to obtain ceramic-metallic composite coating which has improved impact resistance compared to conventional ceramic coating. The high impact resistance of ceramic-metallic composite coating is obtained from dispersed metallic alloy phase in ceramic matrix. Ceramic Matrix Composites (CMC) powder with chrome carbide (Cr3C2) base and ceramic-metal NiAl-Al2O3 with various particle sizes as reinforced particle was deposited on mild steel substrate with High Velocity Oxygen Fuel (HVOF) thermal spray coating. Repeated impact test showed that reinforced metallic phase size influenced impact resistance of CMC coating. The ability of CMC coating to absorb impact energy has improved eight times and ten times compared with original Cr3C2 and hard chrome plating respectively. On the other hand the high temperature corrosion resistance of CMC coating showed up to 31 cycles of heating at 800°C and water quenching cooling.

  12. PComPtm: Nano-Composite Thermal Spray Alternative to Cd and Cr

    DTIC Science & Technology

    2008-02-01

    Rev. 8-98) Prescribed by ANSI Std Z39-18 Acknowledgments EPA Phase I SBIR CONTRACT # EP-D-06-053 Metastructured Cermets for Hard Chrome Replacement...resistance, low friction Ductile binder provides ductility and toughness Working on HVOF, laser cladding , cold spray, and spray and fuse powder designs...nanocomposite core binder coating Thermal spray Microcomposite coating features Micro-Composite Coatings Chrome Plate WC-Co-Cr thermal spray

  13. Thermal spray processing

    NASA Technical Reports Server (NTRS)

    Herman, H.; Berndt, C. C.

    1995-01-01

    Thermal spray processing has been used for a number of years to cost-effecticely apply TBC's for a wide range of heat engine applications. In particular, bond coats are applied by plasma spray and HVOF techniques and partially-stabilized zirconia top coats are applied by plasma spray methods. Thermal spray involves melting and rapid transport of the molten particles to the substrate, where high-rate solidification and coating build-up occur. It is the very nature of this melt processing that leads to the unique layered microstructure, as well as the apparent imperfections, so readily identified with thermal spray. Modeling the process, process-induced residual stresses, and thermal conductivity will be discussed in light of a new understanding of porosity and its anisotropy. Microcracking can be understood using new approaches, allowing a fuller view of the processing-performance connection. Detailed electron microscopic, novel neutron diffraction and fracture analysis of the deposits can lead to a better understanding of how overall microstructure can be controlled to influence critical properties of the deposited TBC system.

  14. Deposition and properties of high-velocity-oxygen-fuel and plasma-sprayed Mo-Mo2C composite coatings

    NASA Astrophysics Data System (ADS)

    Prchlik, L.; Gutleber, J.; Sampath, S.

    2001-12-01

    Molybdenum thermal-spray coatings, dispersion strengthened by molybdenum oxides and molybdenum carbides, play an important role in industrial tribological applications. Traditionally, they have been prepared by plasma and wire flame spraying. High porosity and lower cohesion strength limit their application in situations where both galling and abrasion wear is involved. In this study, high-velocity-oxygen-fuel (HVOF) deposition of molybdenum and molybdenum carbide coatings was attempted. Deposition was achieved for all powders used. Composition, microstructure, mechanical, and wear properties of the HVOF synthesized coatings were evaluated and compared with plasma-sprayed counterparts. The HVOF coatings possessed a very good abrasion resistance, whereas plasma deposits performed better in dry sliding tests. Measurements showed a close relationship between the coating surface hardness and its abrasion resistance. Results also suggested correlation between molybdenum carbide distribution in the molybdenum matrix and the sliding friction response of Mo-Mo2C coatings.

  15. Residual Strain and Fracture Response of Al2O3 Coatings Deposited via APS and HVOF Techniques

    NASA Astrophysics Data System (ADS)

    Ahmed, R.; Faisal, N. H.; Paradowska, A. M.; Fitzpatrick, M. E.

    2012-01-01

    The aim of this investigation was to nondestructively evaluate the residual stress profile in two commercially available alumina/substrate coating systems and relate residual stress changes with the fracture response. Neutron diffraction, due to its high penetration depth, was used to measure residual strain in conventional air plasma-sprayed (APS) and finer powder high velocity oxy-fuel (HVOF (θ-gun))-sprayed Al2O3 coating/substrate systems. The purpose of this comparison was to ascertain if finer powder Al2O3 coatings deposited via θ-gun can provide improved residual stress and fracture response in comparison to conventional APS coatings. To obtain a through thickness residual strain profile with high resolution, a partially submerged beam was used for measurements near the coating surface, and a beam submerged in the coating and substrate materials near the coating-substrate interface. By using the fast vertical scanning method, with careful leveling of the specimen using theodolites, the coating surface and the coating/substrate interface were located with an accuracy of about 50 μm. The results show that the through thickness residual strain in the APS coating was mainly tensile, whereas the HVOF coating had both compressive and tensile residual strains. Further analysis interlinking Vickers indentation fracture behavior using acoustic emission (AE) was conducted. The microstructural differences along with the nature and magnitude of the residual strain fields had a direct effect on the fracture response of the two coatings during the indentation process.

  16. Strength of Rewelded Inconel 718

    NASA Technical Reports Server (NTRS)

    Bayless, E.; Lovoy, C. V.; Mcllwain, M. C.; Munafo, P.

    1982-01-01

    Inconel 718, nickel-based alloy used extensively for high-temperature structural service, welded repeatedly without detriment to its strength. According to NASA report, tests show 12 repairs on same weld joint do not adversely affect ultimate tensile strenth, yield strength, fatigue strength, metallurgical grain structures, or ability of weld joint to respond to post weld heat treatments.

  17. A Numerical Study on Gas Phase Dynamics of High-Velocity Oxygen Fuel Thermal Spray

    NASA Astrophysics Data System (ADS)

    Baik, Jae-Sang; Park, Sun-Kyu; Kim, Youn-Jea

    2008-08-01

    The high-velocity oxygen fuel (HVOF) thermal spray is used for a particulate deposition process in which micro-sized particles are propelled and heated in a supersonic combusting gas stream. It is characterized by high gas velocity and high density and is being used in an increasing variety of coating applications, such as ceramic and composite coatings, to improve wear and abrasion resistance. The particle temperature and velocity are two of the most important parameters in HVOF thermal spraying, which affect the quality of the coatings. To understand the particle dynamics, it is necessary to study, first, the thermal flow characteristics in the HVOF system. In this study, a numerical analysis is performed to predict the gas dynamic behaviors, and the effect of the geometrical parameter is studied to optimize the nozzle design.

  18. Characterization of carbon deposits from jet fuel on Inconel 600 and Inconel X surfaces

    SciTech Connect

    Altin, O.; Eser, S.

    2000-03-01

    Flow reactor experiments were conducted to study carbon deposit formation from decomposition of a jet fuel (JP-8) at 500 C and 500 psig for 5 h on the surface of two superalloys, Inconel 600 and Inconel X. The deposits collected on superalloy surfaces were characterized by temperature-programmed oxidation, size exclusion microscopy, and energy-dispersive X-ray spectroscopy. Significantly lower deposition on Inconel X compared to that on Inconel 600 was attributed to the presence of minor elemental compounds, such as Al, T, Nb, and Ta in the Inconel X alloy.

  19. Sensors in Spray Processes

    NASA Astrophysics Data System (ADS)

    Fauchais, P.; Vardelle, M.

    2010-06-01

    This paper presents what is our actual knowledge about sensors, used in the harsh environment of spray booths, to improve the reproducibility and reliability of coatings sprayed with hot or cold gases. First are described, with their limitations and precisions, the different sensors following the in-flight hot particle parameters (trajectories, temperatures, velocities, sizes, and shapes). A few comments are also made about techniques, still under developments in laboratories, to improve our understanding of coating formation such as plasma jet temperature measurements in non-symmetrical conditions, hot gases heat flux, particles flattening and splats formation, particles evaporation. Then are described the illumination techniques by laser flash of either cold particles (those injected in hot gases, or in cold spray gun) or liquid injected into hot gases (suspensions or solutions). The possibilities they open to determine the flux and velocities of cold particles or visualize liquid penetration in the core of hot gases are discussed. Afterwards are presented sensors to follow, when spraying hot particles, substrate and coating temperature evolution, and the stress development within coatings during the spray process as well as the coating thickness. The different uses of these sensors are then described with successively: (i) Measurements limited to particle trajectories, velocities, temperatures, and sizes in different spray conditions: plasma (including transient conditions due to arc root fluctuations in d.c. plasma jets), HVOF, wire arc, cold spray. Afterwards are discussed how such sensor data can be used to achieve a better understanding of the different spray processes, compare experiments to calculations and improve the reproducibility and reliability of the spray conditions. (ii) Coatings monitoring through in-flight measurements coupled with those devoted to coatings formation. This is achieved by either maintaining at their set point both in-flight and

  20. HVOF and HVAF Coatings of Agglomerated Tungsten Carbide-Cobalt Powders for Water Droplet Erosion Application

    NASA Astrophysics Data System (ADS)

    Tarasi, F.; Mahdipoor, M. S.; Dolatabadi, A.; Medraj, M.; Moreau, C.

    2016-12-01

    Water droplet erosion (WDE) is a phenomenon caused by impingement of water droplets of several hundred microns to a few millimeters diameter at velocities of hundreds of meters per second on the edges and surfaces of the parts used in such services. The solution to this problem is sought especially for the moving compressor blades in gas turbines and those operating at the low-pressure end of steam turbines. Thermal-sprayed tungsten carbide-based coatings have been the focus of many studies and are industrially accepted for a multitude of wear and erosion resistance applications. In the present work, the microstructure, phase analysis and mechanical properties (micro-hardness and fracture toughness) of WC-Co coatings are studied in relation with their influence on the WDE resistance of such coatings. The coatings are deposited by high-velocity oxygen fuel (HVOF) and high-velocity air fuel (HVAF) processes. The agglomerated tungsten carbide-cobalt powders were in either sintered or non-sintered conditions. The WDE tests were performed using 0.4 mm water droplets at 300 m/s impact velocity. The study shows promising results for this cermet as WDE-resistant coating when the coating can reach its optimum quality using the right thermal spray process and parameters.

  1. Characterization of thermal sprayed nanostructured WC-Co coatings derived from nanocrystalline WC-18wt.%Co powders

    NASA Astrophysics Data System (ADS)

    Ban, Z.-G.; Shaw, L. L.

    2003-03-01

    Nanostructured WC-Co coatings were synthesized using high velocity oxygen fuel (HVOF) thermal spray. The nanocrystalline feedstock powder with a nominal composition of WC-18 wt.%Co was prepared using the novel integrated mechanical and thermal activation (IMTA) process. The effects of HVOF thermal spray conditions and powder characteristics on the microstructure and mechanical properties of the as-sprayed WC-Co coatings were studied. It was found that the ratio of oxygen-to-hydrogen flow rate (ROHFR) and the starting powder microstructures had strong effects on decarburization of the nano-coatings. Decarburization was significantly suppressed at low ROHFR and with the presence of free carbon in the powder. The level of porosity in the coatings was correlated with the powder microstructure and spray process conditions. The coating sprayed at ROHFR=0.5 exhibited the highest microhardness value (HV300g=1077), which is comparable to that of conventional coarse-grained coatings.

  2. Effect of HVOF Processing Parameters on the Properties of NiCoCrAlY Coatings by Design of Experiments

    NASA Astrophysics Data System (ADS)

    Ruiz-Luna, H.; Lozano-Mandujano, D.; Alvarado-Orozco, J. M.; Valarezo, A.; Poblano-Salas, C. A.; Trápaga-Martínez, L. G.; Espinoza-Beltrán, F. J.; Muñoz-Saldaña, J.

    2014-08-01

    The effect of three principal, independent, high-velocity oxygen fuel (HVOF)-processing parameters on the properties of NiCoCrAlY coatings deposited using commercial powders is reported here. The design of experiments (DoE) technique at a two-level factorial and a central composite rotatable design was used to analyze and optimize the HVOF spraying process. The deposition parameters investigated were (1) fuel flow, (2) oxygen flow, and (3) stand-off distance. The effect of these processing variables was evaluated using selected responses, including porosity and oxide content, residual stresses, and deposition efficiency. Coatings with low porosity as well as with low residual stress were obtained using high fuel-rich conditions at a stand-off distance between 250 and 300 mm. At shorter and longer stand-off distances, respectively, either excessive flattening of splats or un-molten condition occurred, resulting in high levels of porosity and residual stress. The response surface, the empirical relationships among the variables, and the response parameters allowed the selection of optimum deposition parameters and the improvement of coating properties.

  3. Computer experiment on studying the properties of thermally sprayed alumina coatings with lamellar structure

    NASA Astrophysics Data System (ADS)

    Jordan, V. I.; Solonenko, O. P.; Blednov, V. A.

    2017-05-01

    Results of stochastic modeling of lamellar structure formation and characteristics (microstructure, porosity, roughness) of ceramic coatings made of corundum powders (α-phase of Al2O3) are given in conditions typical for atmospheric plasma spraying (APS), and also detonation and supersonic flame spraying (HVOF). Comparison of characteristics of coatings for two model splats morphologies at their random laying on the base surface is presented.

  4. Comparison of the Mechanical and Electrochemical Properties of WC-25Co Coatings Obtained by High Velocity Oxy-Fuel and Cold Gas Spraying

    NASA Astrophysics Data System (ADS)

    Couto, M.; Dosta, S.; Fernández, J.; Guilemany, J. M.

    2014-12-01

    Cold gas spray (CGS) coatings were previously produced by spraying WC-25Co cermet powders onto Al7075-T6 and low-carbon steel substrates. Unlike conventional flame spray techniques (e.g., high-velocity oxy-fuel; HVOF), no melting of the powder occurs; the particles are deformed and bond together after being sprayed by a supersonic jet of compressed gas, thereby building up several layers and forming a coating. WC-Co cermets are used in wear-resistant parts, because of their combination of mechanical, physical, and chemical properties. XRD tests were previously run on the initial powder and the coatings to determine possible phase changes during spraying. The bonding strength of the coatings was measured by adhesion tests. Here, WC-25Co coatings were also deposited on the same substrates by HVOF spraying. The wear resistance and fracture toughness of the coatings obtained previously by CGS and the HVOF coatings obtained here were studied. Their corrosion resistance was determined by electrochemical measurements. It was possible to achieve thick, dense, and hard CGS coatings on Al7075-T6 and low-carbon steel substrates, with better or the same mechanical and electrochemical properties as those of the HVOF coatings; making the former a highly competitive method for producing WC-25Co coatings.

  5. Evaluation of High Velocity Oxygen Fuel (HVOF) Al/SiCp Coatings as Corrosion Control Coatings for Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Taltavull, C.; Lopez, A. J.; Torres, B.; Rams, J.

    2014-06-01

    High velocity oxygen-fuel (HVOF) thermal spray technique has been used to fabricate Al and MMC (Al/SiCp) coatings on the AZ91 Mg alloy as a corrosion-control coatings. Corrosion behaviour of the coated specimens had been evaluated by electrochemical tests which revealed that some coated specimens presented an improvement on the corrosion behaviour of the AZ91 substrate. Taguchi DOE method has been used to analyse the relationship between the spraying conditions, i.e. spraying distance, % SiCp in feedstock, number of layers deposited and gun speed, and the corrosion behaviour of the coated specimens. In addition, a relationship between the coating characteristic, i.e. thickness, porosity, adhesion and roughness, and the corrosion behaviour of the coated specimens had also been studied. Optimum spraying conditions were fabricated and corrosion tested to validate the Taguchi DOE method analysis. Among the different coatings features, thickness and compactness seems to be the most relevant ones in terms of corrosion.

  6. Machinability studies on INCONEL 718

    NASA Astrophysics Data System (ADS)

    Xavior, M. Anthony; Patil, Mahesh; Maiti, Abheek; Raj, Mrinal; Lohia, Nitesh

    2016-09-01

    The main objective of proposed work is to determine the influence of controllable parameters on machining characteristics of Inconel-718 and to achieve the optimum parameters for sustainable and efficient turning. Understanding the consequences of advanced tool materials together with higher cutting speeds on the formation of residual stresses and therefore the underlying mechanisms of small structural alteration within the subterranean layer thereby becomes terribly crucial for predicting product quality and more optimizing the machining conditions. Controllable cutting parameters such as cutting velocity, feed rate and depth of cut were selected at different level for experimentations in accordance with the Taguchi L9 array method using Minimum Quantity Lubrication (MQL) cutting condition and three different tools namely PVD TiAlN carbide, Cubic boron nitride and ceramic. Extensive study is done on the resulting surface roughness, surface subsurface hardness, tool wear and chip morphology. The results obtained from each of the tool were thoroughly analyzed and finally the optimized parameters are obtained for efficient machining of Inconel 718.

  7. Structure Property Relationship of Suspension Thermally Sprayed WC-Co Nanocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Ahmed, R.; Faisal, N. H.; Al-Anazi, Nayef M.; Al-Mutairi, S.; Toma, F.-L.; Berger, L.-M.; Potthoff, A.; Polychroniadis, E. K.; Sall, M.; Chaliampalias, D.; Goosen, M. F. A.

    2015-02-01

    Tribomechanical properties of nanostructured coatings deposited by suspension high velocity oxy-fuel (S-HVOF) and conventional HVOF (Jet Kote) spraying were evaluated. Nanostructured S-HVOF coatings were obtained via ball milling of the agglomerated and sintered WC-12Co feedstock powder, which were deposited via an aqueous-based suspension using modified HVOF (TopGun) process. Microstructural evaluations of these hardmetal coatings included transmission electron microscopy, x-ray diffraction, and scanning electron microscopy equipped with energy dispersive x-ray spectroscopy. The nanohardness and modulus of the coated specimens were investigated using a diamond Berkovich nanoindenter. Sliding wear tests were conducted using a ball-on-flat test rig. Results indicated that low porosity coatings with nanostructured features were obtained. High carbon loss was observed, but coatings showed a high hardness up to 1000 HV2.9N. S-HVOF coatings also showed improved sliding wear and friction behavior, which were attributed to nanosized particles reducing ball wear in three-body abrasion and support of metal matrix due to uniform distribution of nanoparticles in the coating microstructure.

  8. The Role of Oxide Tribofilms on Friction and Wear of Different Thermally Sprayed WC-CoCr

    NASA Astrophysics Data System (ADS)

    Wesmann, J. A. R.; Kuroda, S.; Espallargas, N.

    2017-01-01

    The tribolgical response of five different thermal sprayed WC-CoCr coatings sprayed with HVOF (JP-5000), HVAF (UniqueCoat M3) and Warm Spray (NIMS, Japan) has been evaluated during dry sliding in air and in nitrogen gas. Tests were conducted at room temperature and at 200 °C where both friction and wear were evaluated. Test results indicate that the HVAF and Warm Spray coatings were most dense, while HVOF coatings showed higher degree of porosity and discontinuities in the cross sections. Results show that the sliding atmosphere affects both friction and wear: Sliding in nitrogen reduced predominantly specific wear rate as well as friction coefficient. Higher friction was linked to the formation of tribofilms on the surfaces, aided by higher oxygen content in the sliding atmosphere and temperature.

  9. The Role of Oxide Tribofilms on Friction and Wear of Different Thermally Sprayed WC-CoCr

    NASA Astrophysics Data System (ADS)

    Wesmann, J. A. R.; Kuroda, S.; Espallargas, N.

    2017-02-01

    The tribolgical response of five different thermal sprayed WC-CoCr coatings sprayed with HVOF (JP-5000), HVAF (UniqueCoat M3) and Warm Spray (NIMS, Japan) has been evaluated during dry sliding in air and in nitrogen gas. Tests were conducted at room temperature and at 200 °C where both friction and wear were evaluated. Test results indicate that the HVAF and Warm Spray coatings were most dense, while HVOF coatings showed higher degree of porosity and discontinuities in the cross sections. Results show that the sliding atmosphere affects both friction and wear: Sliding in nitrogen reduced predominantly specific wear rate as well as friction coefficient. Higher friction was linked to the formation of tribofilms on the surfaces, aided by higher oxygen content in the sliding atmosphere and temperature.

  10. Effect of Operating Parameters on a Dual-Stage High Velocity Oxygen Fuel Thermal Spray System

    NASA Astrophysics Data System (ADS)

    Khan, Mohammed N.; Shamim, Tariq

    2014-08-01

    High velocity oxygen fuel (HVOF) thermal spray systems are being used to apply coatings to prevent surface degradation. The coatings of temperature sensitive materials such as titanium and copper, which have very low melting points, cannot be applied using a single-stage HVOF system. Therefore, a dual-stage HVOF system has been introduced and modeled computationally. The dual-spray system provides an easy control of particle oxidation by introducing a mixing chamber. In addition to the materials being sprayed, the thermal spray coating quality depends to a large extent on flow behavior of reacting gases and the particle dynamics. The present study investigates the influence of various operating parameters on the performance of a dual-stage thermal spray gun. The objective is to develop a predictive understanding of various parameters. The gas flow field and the free jet are modeled by considering the conservation of mass, momentum, and energy with the turbulence and the equilibrium combustion sub models. The particle phase is decoupled from the gas phase due to very low particle volume fractions. The results demonstrate the advantage of a dual-stage system over a single-stage system especially for the deposition of temperature sensitive materials.

  11. Thermal Spray Coatings for High-Temperature Corrosion Protection in Biomass Co-Fired Boilers

    NASA Astrophysics Data System (ADS)

    Oksa, M.; Metsäjoki, J.; Kärki, J.

    2015-01-01

    There are over 1000 biomass boilers and about 500 plants using waste as fuel in Europe, and the numbers are increasing. Many of them encounter serious problems with high-temperature corrosion due to detrimental elements such as chlorides, alkali metals, and heavy metals. By HVOF spraying, it is possible to produce very dense and well-adhered coatings, which can be applied for corrosion protection of heat exchanger surfaces in biomass and waste-to-energy power plant boilers. Four HVOF coatings and one arc sprayed coating were exposed to actual biomass co-fired boiler conditions in superheater area with a probe measurement installation for 5900 h at 550 and 750 °C. The coating materials were Ni-Cr, IN625, Fe-Cr-W-Nb-Mo, and Ni-Cr-Ti. CJS and DJ Hybrid spray guns were used for HVOF spraying to compare the corrosion resistance of Ni-Cr coating structures. Reference materials were ferritic steel T92 and nickel super alloy A263. The circulating fluidized bed boiler burnt a mixture of wood, peat and coal. The coatings showed excellent corrosion resistance at 550 °C compared to the ferritic steel. At higher temperature, NiCr sprayed with CJS had the best corrosion resistance. IN625 was consumed almost completely during the exposure at 750 °C.

  12. Thermal Spray Coatings for High-Temperature Corrosion Protection in Biomass Co-Fired Boilers

    NASA Astrophysics Data System (ADS)

    Oksa, M.; Metsäjoki, J.; Kärki, J.

    2014-09-01

    There are over 1000 biomass boilers and about 500 plants using waste as fuel in Europe, and the numbers are increasing. Many of them encounter serious problems with high-temperature corrosion due to detrimental elements such as chlorides, alkali metals, and heavy metals. By HVOF spraying, it is possible to produce very dense and well-adhered coatings, which can be applied for corrosion protection of heat exchanger surfaces in biomass and waste-to-energy power plant boilers. Four HVOF coatings and one arc sprayed coating were exposed to actual biomass co-fired boiler conditions in superheater area with a probe measurement installation for 5900 h at 550 and 750 °C. The coating materials were Ni-Cr, IN625, Fe-Cr-W-Nb-Mo, and Ni-Cr-Ti. CJS and DJ Hybrid spray guns were used for HVOF spraying to compare the corrosion resistance of Ni-Cr coating structures. Reference materials were ferritic steel T92 and nickel super alloy A263. The circulating fluidized bed boiler burnt a mixture of wood, peat and coal. The coatings showed excellent corrosion resistance at 550 °C compared to the ferritic steel. At higher temperature, NiCr sprayed with CJS had the best corrosion resistance. IN625 was consumed almost completely during the exposure at 750 °C.

  13. Preliminary Tuft Testing of Metallic Bristles Versus PS212, PS300, and HVOF300

    NASA Technical Reports Server (NTRS)

    Fellenstein, James A.; DellaCorte, Christopher

    1998-01-01

    Turbine engine brush seals are designed with sacrificial brushes and hard shaft coatings to minimize shaft wear and reduce the cost of engine overhauls. Replacing a worm seal is more cost and time effective than refinishing an engine shaft. However, this tribological design causes excessive brush wear and reduces long term seal efficiency. An alternative approach is to coat the shaft with a solid lubricant and allow the bristles to wear into the shaft coating similar to traditional abradable labyrinth seals. This approach can result in reduced seal leakage by forcing the leakage to flow through the seal bristle pack or through a more tortuous shaft wear track. Key to this approach is limiting the shaft wear to an acceptable level were surface refinishing would not be required during every engine overhaul. Included in this paper are brush seal tuft test results for four metallic bristles (nickel-chrome or cobalt-chrome based superalloys) tested against three solid lubricant coatings (NASA's PS212, PS300, and HVOF300). These test results are also compared to previous baseline tests conducted with plasma sprayed chrome carbide. Compared to the baseline results, no tribological benefit was achieved with the metallic bristle/solid lubricant tribopairs tested. To improve the performance of the solid lubricant coatings, issues regarding lubricant phase sizes (homogeneity), and composition need to be addressed.

  14. Characterization of Thermal Sprayed Aluminum and Stainless Steel Coatings for Clean Laser Enclosures

    SciTech Connect

    Chow, R; Decker, T A; Gansert, R V; Gansert, D

    2000-04-06

    Surfaces of steel structures that enclose high-fluence, large-beam lasers have conventional and unconventional requirements. Aside from rust prevention, the surfaces must resist laser-induced degradation and the contamination of the optical components. The latter requires a surface that can be precision cleaned to low levels of particulate and organic residue. In addition, the surface treatment for the walls should be economical to apply because of the large surface areas involved, and accommodating with intricate joint geometries. Thermal sprayed coatings of aluminum (Al) and stainless steel are candidate surface materials. Coatings are produced and characterized for porosity, smoothness, and hardness. These properties have a bearing on the cleanliness of the coating. The laser resistance of Al and 3 16L coatings are given. The paper summarizes the characterization of twin-wire-arc deposited Al, high-velocity-oxygen-fueled (HVOF) deposited Al, flame-sprayed 316L, and HVOF deposited316L. The most promising candidate coating is that of HVOF Al. This Al coating has the lowest porosity (8%) compared the other three coatings and relatively low hardness (100 VHN). The as-deposited roughness (Ra) is 433 pinches, but after a quick sanding by hand, the roughness decreased to 166 pinches. Other post-coat treatments are discussed. HVOF aluminum coatings are demonstrated. Al coatings are corrosion barriers for steel, and this work shows promising resistance to laser damage and low particulation rates.

  15. The Gas Dynamics of High-Velocity Oxy-Fuel Thermal Sprays

    NASA Astrophysics Data System (ADS)

    Hackett, Charles Marcou

    An experimental study of the gas dynamics of the High-Velocity Oxy-Fuel (HVOF) thermal spray process has been performed. With this process, a hot, combustion-driven, supersonic jet is used to propel particles onto a surface, thus forming metal coatings that provide wear, temperature, and corrosion resistance. The fundamental physics of the spray process were studied and several key areas of interest were identified for in-depth study. Optical diagnostic techniques, including microsecond -exposure schlieren and shadowgraph imaging, were used to visualize the hot supersonic jet produced during the spray process. Energetic turbulent mixing of the jet with the surrounding atmosphere was observed. Measurements of oxide levels in aluminum and mild steel coatings sprayed for a range of conditions indicated that the turbulent mixing influences coating oxidation. However, experiments conducted with a low-speed coaxial shroud of inert gas demonstrated that coating oxide formation can be effectively controlled during the spray process. A simple numerical model was developed to predict the behavior of a spray particle in the HVOF jet. The results of computations indicated that independent control of spray particle velocity and temperature was possible through systematic variations in combustion chamber pressure and particle injection location within the nozzle. This hypothesis was confirmed through a series of experiments in which stainless steel particle velocity and temperature were measured using trace velocimetry and two-color radiative pyrometry, respectively. Combustion chamber pressure had a strong effect on particle velocity. Injection location was used to control the residence time of a particle within the flow, thus allowing manipulation of particle temperature without a measurable effect on velocity. Thus, the results of these experiments revealed that the gas dynamics--the behavior of the compressible gas flow--of the HVOF spray process strongly influenced spray

  16. A comparison of two laser-based diagnostics for analysis of particles in thermal spray streams

    SciTech Connect

    Smith, M.F.; O`Hern, T.J.; Brockmann, J.E.

    1995-07-01

    This paper discusses two commercially-available laser diagnostics that have been used in thermal spray research at Sandia National Laboratories: (1) a Phase Doppler Particle Analyzer (PDPA) and (2) a Laser Two-Focus (L2F) velocimeter. The PDPA provides simultaneous, correlated measurements of particle velocity and particle size distributions; but, particle sizing doesn`t work well with non-spherical particles or particles with rough surfaces. The L2F is used to collect particle velocity and number density distributions, and it can readily distinguish and separately measure particles with off-axis velocity vectors. PDPA and L2F principles of operation are presented along with potential advantages and limitations for thermal spray research. Four experiments were conducted to validate and compare measurement results with the PDPA and L2F instruments: (1) spinning wire, (2) powder in a High-Velocity Oxy-Fuel (HVOF) jet, (3) powder in a cold jet, and (4) droplets in a wire-fed HVOF jet. TWO DIFFERENT TYPES of commercially-available laser velocimeter systems, a Phase Doppler Particle Analyzer and a Laser-Two-Focus velocimeter have been used in the Thermal Spray Research Laboratory at Sandia National Laboratories. Each of these techniques has inherent advantages and limitations for thermal spray, and each involves assumptions that may not be valid for some experimental conditions. This paper describes operating principles and possible sources of measurement error for these two diagnostic systems. Some potential advantages and limitations are also presented. Four types of experiments were also conducted to validate and compare PDPA and L2F measurement results: (1) spinning wire, (2) powder in a High-Velocity Oxy-Fuel (HVOF) jet, (3) powder in a cold jet, and (4) droplets in a wire-fed HVOF jet. We also offer a few observations related to practical issues such as ease-of-use, reliability, and effects of dust and vibration in a thermal spray lab.

  17. Optimal Substrate Preheating Model for Thermal Spray Deposition of Thermosets onto Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Ivosevic, M.; Knight, R.; Kalidindi, S. R.; Palmese, G. R.; Tsurikov, A.; Sutter, J. K.

    2003-01-01

    High velocity oxy-fuel (HVOF) sprayed, functionally graded polyimide/WC-Co composite coatings on polymer matrix composites (PMC's) are being investigated for applications in turbine engine technologies. This requires that the polyimide, used as the matrix material, be fully crosslinked during deposition in order to maximize its engineering properties. The rapid heating and cooling nature of the HVOF spray process and the high heat flux through the coating into the substrate typically do not allow sufficient time at temperature for curing of the thermoset. It was hypothesized that external substrate preheating might enhance the deposition behavior and curing reaction during the thermal spraying of polyimide thermosets. A simple analytical process model for the deposition of thermosetting polyimide onto polymer matrix composites by HVOF thermal spray technology has been developed. The model incorporates various heat transfer mechanisms and enables surface temperature profiles of the coating to be simulated, primarily as a function of substrate preheating temperature. Four cases were modeled: (i) no substrate preheating; (ii) substrates electrically preheated from the rear; (iii) substrates preheated by hot air from the front face; and (iv) substrates electrically preheated from the rear and by hot air from the front.

  18. Splat formation during thermal spraying of polymer particles: Mathematical modeling and experimental analysis

    NASA Astrophysics Data System (ADS)

    Ivosevic, Milan

    This thesis develops and presents a model for predicting the three-dimensional splat formation process for polymer particles under High Velocity Oxy-Fuel (HVOF) combustion spray process conditions. During HVOF spray deposition, jets of high temperature, high velocity gases are used to heat, melt and accelerate particulate materials injected into the jet and propel them towards a surface to be coated. Upon impact at the surface, multiple hot particles impact and form splats that overlap, cool and consolidate to form a coating. These splats are the building blocks of an HVOF coating and coating characteristics such as porosity, roughness, adhesive and cohesive strengths depend on the morphology of these splats and how they bond to the substrate and to each other. Fully coupled transport models of particle acceleration and heating in an HVOF jet were simultaneously integrated within a FORTRAN code to predict particle velocity and particle temperature profiles at impact. Then, a volume-of-fluid computational fluid mechanics package, Flow-3DRTM, was used to predict particle deformation and splat shapes using results from the acceleration and heating models as the initial conditions. Fluid flow of spreading polymer droplets was modeled as a generalized Newtonian fluid with temperature and shear rate dependent viscosity. While shear thinning primarily affected the droplet spreading ratio, the internal temperature distribution had the largest effect on the final splat shape, particularly when particles were partially melted. The predicted shapes of deformed particles exhibited good qualitative agreement with experimentally observed splats. Most of the larger experimentally observed (> 70 mum) Nylon-11 splats sprayed onto room temperature flat or rough substrates exhibited a characteristic "fried-egg" shape with a large, nearly-hemispherical, core in the center of a thin disk. This shape was formed from polymer particles having a low temperature, high viscosity core and a

  19. Materials data handbook: Inconel alloy 718

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1972-01-01

    A summary of the materials property information for Inconel alloy 718 is presented. The scope of the information includes physical and mechanical properties at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and joining techniques is developed.

  20. Improved nickel plating of Inconel X-750

    NASA Technical Reports Server (NTRS)

    Farmer, M. E.; Feeney, J. E.; Kuster, C. A.

    1969-01-01

    Electroplating technique with acid pickling provides a method of applying nickel plating on Inconel X-750 tubing to serve as a wetting agent during brazing. Low-stress nickel-plating bath contains no organic wetting agents that cause the nickel to blister at high temperatures.

  1. Comparative characteristic and erosion behavior of NiCr coatings deposited by various high-velocity oxyfuel spray processes

    NASA Astrophysics Data System (ADS)

    Sidhu, Hazoor Singh; Sidhu, Buta Singh; Prakash, S.

    2006-12-01

    The purpose of this study is to analyze and compare the mechanical properties and microstructure details at the interface of high-velocity oxyfuel (HVOF)-sprayed NiCr-coated boiler tube steels, namely ASTM-SA-210 grade A1, ASTM-SA213-T-11, and ASTM-SA213-T-22. Coatings were developed by two different techniques, and in these techniques liquefied petroleum gas was used as the fuel gas. First, the coatings were characterized by metallographic, scanning electron microscopy/energy-dispersive x-ray analysis, x-ray diffraction, surface roughness, and microhardness, and then were subjected to erosion testing. An attempt has been made to describe the transformations taking place during thermal spraying. It is concluded that the HVOF wire spraying process offers a technically viable and cost-effective alternative to HVOF powder spraying process for applications in an energy generation power plant with a point view of life enhancement and to minimize the tube failures because it gives a coating having better resistance to erosion.

  2. Detection of Cracks in Aluminum Structure Beneath Inconel Repair Bushings

    DTIC Science & Technology

    2008-04-01

    conductivity (i.e. Inconel 718 ) – Primary challenge then becomes detecting the weak eddy current field in the structure beyond the bushing wall...was able to be selected with inspectability as a goal. – Inconel 718 • low permeability (~μ0) • low conductivity (< 2% IACS) • Combined with...Detection of Cracks in Aluminum Structure beneath Inconel Repair Bushings Mr. Kenneth J. LaCivita (USAF) AFRL/RXSA Air Force Research Laboratory

  3. Effect of the increase in the entrance convergent section length of the gun nozzle on the high-velocity oxygen fuel and cold spray process

    NASA Astrophysics Data System (ADS)

    Sakaki, K.; Shimizu, Y.

    2001-09-01

    Nozzle geometry, which influences combustion gas dynamics and, therefore, sprayed particle behavior, is one of the most important parameters in the high-velocity oxygen-fuel (HVOF) thermal spray process. The nozzle geometry is also important in the cold spray method. The gas flows in the entrance convergent section of the nozzle exhibit a relatively higher temperature and are subsonic; thus, this region is most suitable for heating spray particles. In this study, numerical simulation and experiments investigated the effect of the entrance geometry of the gun nozzle on the HVOF process. The process changes inside the nozzle, as obtained by numerical simulation studies, were related to the coating properties. An Al2O3-40 mass% TiO2 powder was used for the experimental studies. The change in entrance convergent section length (rather than barrel part length or total length) of the gun nozzle had a significant effect on the deposition efficiency, microstructure, and hardness. The deposition efficiency and hardness increased as this geometry increased. On the other hand, the calculated and measured particle velocity showed a slight decrease. This effect on the HVOF process will also be applied to the nozzle design for the cold spray method.

  4. Microstructural Evolution of Inconel 625 and Inconel 686CPT Weld Metal for Clad Carbon Steel Linepipe Joints: A Comparator Study

    NASA Astrophysics Data System (ADS)

    Maltin, Charles A.; Galloway, Alexander M.; Mweemba, Martin

    2014-07-01

    Microstructural evolution of Inconel 625 and Inconel 686CPT filler metals, used for the fusion welding of clad carbon steel linepipe, has been investigated and compared. The effects of iron dilution from the linepipe parent material on the elemental segregation potential of the filler metal chemistry have been considered. The results obtained provide significant evidence to support the view that, in Inconel 686CPT weld metal, the segregation of tungsten is a function of the level of iron dilution from the parent material. The data presented indicate that the incoherent phase precipitated in the Inconel 686CPT weld metal has a morphology that is dependent on tungsten enrichment and, therefore, iron dilution. Furthermore, in the same weld metal, a continuous network of finer precipitates was observed. The Charpy impact toughness of each filler metal was evaluated, and the results highlighted the superior impact toughness of the Inconel 625 weld metal over that of Inconel 686CPT.

  5. Influence of Fracture Toughness and Microhardness on the Erosive Wear of Cermet Coatings Deposited by Thermal Spray

    NASA Astrophysics Data System (ADS)

    Mojena, Miguel Reyes; Orozco, Mario Sánchez; Fals, Hipólito Carvajal; Ferraresi, Valtair Antonio; Lima, Carlos Roberto Camello

    2017-02-01

    An evaluation of the relationship between the microhardness and fracture toughness with resistance to erosive wear of WC10Co4Cr, WC-12Co, and Cr3C2-25NiCr coatings was conducted. Powder and flexible cored wire feedstock materials were applied by high-velocity oxygen fuel (HVOF) and flame spray (FS), respectively. The erosive wear mechanism prevailing in the coatings was found to be brittle, which also explains the higher erosion rate for the experimental condition using the particle impact angle of 90 deg and impact velocity of 9.33 m/s. The best wear performance was for the coatings applied by HVOF that attains 1.83 mm3/kg for the 90 deg/3.61 m/s test condition. The coating obtained with the WC-10Co4Cr material using the FSFC method showed tungsten carbide decarburization, justifying its poor mechanical properties and poor performance in the erosive wear test. Flame-sprayed flexicords proved to be a promising alternative to HVOF in obtaining coatings with low porosity and acceptable mechanical properties, especially in applications where the use of the HVOF technique is inadequate because of inaccessibility or excessively high cost. Values of K c for the coatings obtained by HVOF (7.35 to 10.83 MPa.m1/2) were between two and three times greater than the values obtained for the coatings resulting from FSFC (2.39 to 3.59 MPa.m1/2), in a similar manner as with the microhardness.

  6. Influence of Fracture Toughness and Microhardness on the Erosive Wear of Cermet Coatings Deposited by Thermal Spray

    NASA Astrophysics Data System (ADS)

    Mojena, Miguel Reyes; Orozco, Mario Sánchez; Fals, Hipólito Carvajal; Ferraresi, Valtair Antonio; Lima, Carlos Roberto Camello

    2017-05-01

    An evaluation of the relationship between the microhardness and fracture toughness with resistance to erosive wear of WC10Co4Cr, WC-12Co, and Cr3C2-25NiCr coatings was conducted. Powder and flexible cored wire feedstock materials were applied by high-velocity oxygen fuel (HVOF) and flame spray (FS), respectively. The erosive wear mechanism prevailing in the coatings was found to be brittle, which also explains the higher erosion rate for the experimental condition using the particle impact angle of 90 deg and impact velocity of 9.33 m/s. The best wear performance was for the coatings applied by HVOF that attains 1.83 mm3/kg for the 90 deg/3.61 m/s test condition. The coating obtained with the WC-10Co4Cr material using the FSFC method showed tungsten carbide decarburization, justifying its poor mechanical properties and poor performance in the erosive wear test. Flame-sprayed flexicords proved to be a promising alternative to HVOF in obtaining coatings with low porosity and acceptable mechanical properties, especially in applications where the use of the HVOF technique is inadequate because of inaccessibility or excessively high cost. Values of K c for the coatings obtained by HVOF (7.35 to 10.83 MPa.m1/2) were between two and three times greater than the values obtained for the coatings resulting from FSFC (2.39 to 3.59 MPa.m1/2), in a similar manner as with the microhardness.

  7. Some aspects of inelastic behavior of high temperature alloys -- Inconel 700 and Inconel 713

    SciTech Connect

    Anselmo, E.R.; French, M.; Jones, D.I.G.

    1995-12-31

    The Renewal Theory of Inelasticity is used to describe the behavior of high temperature alloys Inconel 700 and Inconel 713C. Renewal Creep Theory is used to model the primary and secondary behavior of these alloys. The numerical parameters extracted from the creep model are then used with the Renewal Theory of Inelasticity to predict stress-strain behaviors of the alloys. Comparisons between theory,and experimental results support the utility of the general form of Renewal Theory. This work also serves as a tutorial on applying renewal theory to an engineering material.

  8. APS TBC performance on directionally-solidified superalloy substrates with HVOF NiCoCrAlYHfSi bond coatings

    DOE PAGES

    Lance, Michael J.; Unocic, Kinga A.; Haynes, James A.; ...

    2015-09-04

    Directionally-solidified (DS) superalloy components with advanced thermal barrier coatings (TBC) to lower the metal operating temperature have the potential to replace more expensive single crystal superalloys for large land-based turbines. In order to assess relative TBC performance, furnace cyclic testing was used with superalloys 1483, X4 and Hf-rich DS 247 substrates and high velocity oxygen fuel (HVOF)-NiCoCrAlYHfSi bond coatings at 1100 °C with 1-h cycles in air with 10% H2O. With these coating and test conditions, there was no statistically-significant effect of substrate alloy on the average lifetime of the air plasma sprayed (APS) yttria-stabilized zirconia (YSZ) top coatings onmore » small coupons. Using photo-stimulated luminescence piezospectroscopy maps at regular cycling intervals, the residual compressive stress in the α-Al2O3 scale underneath the YSZ top coating and on a bare bond coating was similar for all three substrates and delaminations occurred at roughly the same rate and frequency. As a result, x-ray fluorescence (XRF) measurements collected from the bare bond coating surface revealed higher Ti interdiffusion occurring with the 1483 substrate, which contained the highest Ti content.« less

  9. APS TBC performance on directionally-solidified superalloy substrates with HVOF NiCoCrAlYHfSi bond coatings

    SciTech Connect

    Lance, Michael J.; Unocic, Kinga A.; Haynes, James A.; Pint, Bruce A.

    2015-09-04

    Directionally-solidified (DS) superalloy components with advanced thermal barrier coatings (TBC) to lower the metal operating temperature have the potential to replace more expensive single crystal superalloys for large land-based turbines. In order to assess relative TBC performance, furnace cyclic testing was used with superalloys 1483, X4 and Hf-rich DS 247 substrates and high velocity oxygen fuel (HVOF)-NiCoCrAlYHfSi bond coatings at 1100 °C with 1-h cycles in air with 10% H2O. With these coating and test conditions, there was no statistically-significant effect of substrate alloy on the average lifetime of the air plasma sprayed (APS) yttria-stabilized zirconia (YSZ) top coatings on small coupons. Using photo-stimulated luminescence piezospectroscopy maps at regular cycling intervals, the residual compressive stress in the α-Al2O3 scale underneath the YSZ top coating and on a bare bond coating was similar for all three substrates and delaminations occurred at roughly the same rate and frequency. As a result, x-ray fluorescence (XRF) measurements collected from the bare bond coating surface revealed higher Ti interdiffusion occurring with the 1483 substrate, which contained the highest Ti content.

  10. From Powders to Thermally Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Fauchais, Pierre; Montavon, Ghislain; Bertrand, Ghislaine

    2010-01-01

    Since the early stages of thermal spray, it has been recognized that the powder composition, size distribution, shape, mass density, mechanical resistance, components distribution for composite particles play a key role in coating microstructure and thermo mechanical properties. The principal characteristics of particles are strongly linked to the manufacturing process. Coatings also depend on the process used to spray particles and spray parameters. Many papers have been devoted to the relationships existing between coating properties and structures at different scales and manufacturing processes. In many conventional spray conditions resulting in micrometric structures, among the different parameters, good powder flow ability, and dense particles are important features. Thermal plasma treatment, especially by RF plasma, of particles, prepared by different manufacturing processes, allows achieving such properties and it is now developed at an industrial scale. Advantages and drawbacks of this process will be discussed. Another point, which will be approached, is the self-propagating high-temperature synthesis, depending very strongly upon the starting composite particle manufacturing. However, as everybody knows, "small is beautiful" and nano- or finely structured coatings are now extensively studied with spraying of: (i) very complex alloys containing multiple elements which exhibit a glass forming capability when cooled-down, their under-cooling temperature being below the glass transition temperature; (ii) conventional micrometer-sized particles (in the 30-90 μm range) made of agglomerated nanometer-sized particles; (iii) sub-micrometer- or nanometer-sized particles via a suspension in which also, instead of particles, stable sol of nanometer-sized particles can be introduced; and (iv) spray solutions of final material precursor. These different processes using plasma, HVOF or sometimes flame and also cold-gas spray will be discussed together with the

  11. Laser cladding of Inconel 690 on Inconel 600 superalloy for corrosion protection in nuclear applications

    NASA Astrophysics Data System (ADS)

    Baldridge, T.; Poling, G.; Foroozmehr, E.; Kovacevic, R.; Metz, T.; Kadekar, V.; Gupta, M. C.

    2013-02-01

    In the nuclear industry there is need for repair of heat exchanger tubes made of high-temperature corrosion-resistant Inconel metals. This work reports the results of applying a 3 mm thick cladding layer by laser melting Inconel 690 powder on top of a 10 mm thick plate of Inconel 600 alloy substrate. Successful multilayer cladding of 3 mm thickness was achieved by scanning the laser beam over the substrate using a powder feeder to control the powder feed rate. Experimental parameters such as laser power, scanning speed, beam overlap, powder feed rate, and preheating were investigated to reduce cracking upon cooling. SEM images show a smooth integral interface between the 600 and 690 materials, and EDS mapping reveals the dilution zone via the concentration gradient of chromium. Vickers tests show the 690 cladding surface to be up to 40% harder than the base 600 material. XRD and EDS analysis confirm that the Inconel 690 composition remains unchanged throughout processing when using argon as a shielding gas. The final laser melted cladding layer appears to be well-suited for surface protection.

  12. Corrosion Performance of Inconel 625 in High Sulphate Content

    NASA Astrophysics Data System (ADS)

    Ismail, Azzura

    2016-05-01

    Inconel 625 (UNS N06625) is a type of nickel-chromium-molybdenum alloy with excellent corrosion resistance in a wide range of corrosive media, being especially resistant to pitting and crevice corrosion. However, in aggressive environment, Inconel 625 will suffer corrosion attack like other metals. This research compared the corrosion performance of Inconel 625 when exposed to higher sulphate content compared to real seawater. The results reveal that Inconel 625 is excellent in resist the corrosion attack in seawater. However, at increasing temperature, the corrosion resistance of this metal decrease. The performance is same in seawater with high sulphate content at increasing temperature. It can be concluded that sulphate promote perforation on Inconel 625 and become aggressive agents that accelerate the corrosion attack.

  13. Vacuum plasma spray applications on liquid fuel rocket engines

    NASA Technical Reports Server (NTRS)

    Mckechnie, T. N.; Zimmerman, F. R.; Bryant, M. A.

    1992-01-01

    The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z, combustion chamber liners, and structural nickel base material, Inconel 718, for nozzle and combustion chamber support jackets.

  14. Vacuum plasma spray applications on liquid fuel rocket engines

    NASA Astrophysics Data System (ADS)

    McKechnie, T. N.; Zimmerman, F. R.; Bryant, M. A.

    1992-07-01

    The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z, combustion chamber liners, and structural nickel base material, Inconel 718, for nozzle and combustion chamber support jackets.

  15. The Dry Sliding Wear Behavior of HVOF-Sprayed WC: Metal Composite Coatings

    NASA Astrophysics Data System (ADS)

    Ward, Liam P.; Pilkington, Antony

    2014-09-01

    WC-based cermet coatings containing various metallic binders such as Ni, Co, and Cr are known for their superior tribological properties, particularly abrasion resistance and enhanced surface hardness. Consequently, these systems are considered as replacements for traditional hard chrome coatings in critical aircraft components such as landing gear. The purpose of this investigation was to conduct a comparative study on the dry sliding wear behavior of three WC-based cermet coatings (WC-12Ni, WC-20Cr2C3-7Ni, and WC-10Co-4Cr), when deposited on carbon steel substrates. Ball on disk wear tests were performed on the coatings using a CSEM Tribometer (pin-on-disk) with a 6-mm ruby ball at 20 N applied load, 0.2 m/s sliding velocity, and sliding distances up to 2000 m. Analysis of both the coating wear track and worn ruby ball was performed using optical microscopy and an Alphastep-250 profilometer. The results of the study revealed both wear of the ruby ball and coated disks allowed for a comparison of both the ball wear and coating wear for the systems considered. Generally, the use of Co and Cr as a binder significantly improved the sliding wear resistance of the coating compared to Ni and/or Cr2C3.

  16. Replacement of Chromium Electroplating on Landing Gear Components Using HVOF Thermal Spray Coatings

    DTIC Science & Technology

    2004-05-01

    Ogden Air Logistics Center • Mr. Robert Kestler, Naval Aviation Depot Cherry Point • Mr. James Candela, Naval Air Systems Command • Mr. Donald...WC/17Co or WC/10Co4Cr sliding against bushings fabricated from 4340 steel, Al-Ni bronze, anodized 2024 Al alloy, a Nitrile seal, or a Karon B seal...or a Karon B seal. The fretting test is illustrated in Figure 8, with the shoe fabricated from 4340 steel and coated with EHC, WC/17Co or WC

  17. Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

    NASA Astrophysics Data System (ADS)

    Bakan, Emine; Marcano, Diana; Zhou, Dapeng; Sohn, Yoo Jung; Mauer, Georg; Vaßen, Robert

    2017-08-01

    Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

  18. Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

    NASA Astrophysics Data System (ADS)

    Bakan, Emine; Marcano, Diana; Zhou, Dapeng; Sohn, Yoo Jung; Mauer, Georg; Vaßen, Robert

    2017-06-01

    Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

  19. Hot tensile tests of Inconel 718

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The physical metallurgy of near-solidus integranular cracking in Inconel 718 welds was investigated. The data, although inconclusive, suggest at least two mechanisms which might explain intergranular cracking (microfissuring) in the heat-affected zone of several high temperature alloys. One theory is based on the separation of intergranular liquid while the other involves mechanical failure of solid ligaments surrounded by intergranular liquid. Both mechanisms concentrate strain in the grain boundaries resulting in low strain (1%) intergranular brittleness. The mechanisms reported might also pertain to the physical metallurgy of casting, powder metallurgy sintering and hot isostatic pressing.

  20. Mechanical and Thermal Transport Properties of Suspension Thermal-Sprayed Alumina-Zirconia Composite Coatings

    NASA Astrophysics Data System (ADS)

    Oberste Berghaus, Jörg; Legoux, Jean-Gabriel; Moreau, Christian; Tarasi, Fariba; Chráska, Tomas

    2008-03-01

    Micro-laminates and nanocomposites of Al2O3 and ZrO2 can potentially exhibit higher hardness and fracture toughness and lower thermal conductivity than alumina or zirconia alone. The potential of these improvements for abrasion protection and thermal barrier coatings is generating considerable interest in developing techniques for producing these functional coatings with optimized microstructures. Al2O3-ZrO2 composite coatings were deposited by suspension thermal spraying (APS and HVOF) of submicron feedstock powders. The liquid carrier employed in this approach allows for controlled injection of much finer particles than in conventional thermal spraying, leading to unique and novel fine-scaled microstructures. The suspensions were injected internally using a Mettech Axial III plasma torch and a Sulzer-Metco DJ-2700 HVOF gun. The different spray processes induced a variety of structures ranging from finely segregated ceramic laminates to highly alloyed amorphous composites. Mechanisms leading to these structures are related to the feedstock size and in-flight particle states upon their impact. Mechanical and thermal transport properties of the coatings were compared. Compositionally segregated crystalline coatings, obtained by plasma spraying, showed the highest hardness of up to 1125 VHN3 N, as well as the highest abrasion wear resistance (following ASTM G65). The HVOF coating exhibited the highest erosion wear resistance (following ASTM G75), which was related to the toughening effect of small dispersed zirconia particles in the alumina-zirconia-alloyed matrix. This microstructure also exhibited the lowest thermal diffusivity, which is explained by the amorphous phase content and limited particle bonding, generating local thermal resistances within the structure.

  1. Microstructure and properties of thermally sprayed Al-Sn-based alloys for plain bearing applications

    NASA Astrophysics Data System (ADS)

    Marrocco, T.; Driver, L. C.; Harris, S. J.; McCartney, D. G.

    2006-12-01

    Al-Sn plain bearings for automotive applications traditionally comprise a multilayer structure. Conventionally, bearing manufacturing involves casting the Al-Sn alloy and roll-bonding to a steel backing strip. Recently, high-velocity oxyfuel (HVOF) thermal spraying has been used as a novel alternative manufacturing route. The present project extends previous work on ternary Al-Sn-Cu alloys to quaternary systems, which contain specific additions for potentially enhanced properties. Two alloys were studied in detail, namely, Al-20wt.%Sn-1wt.%Cu-2wt.%Ni and Al-20wt.%Sn-1wt.%Cu-7wt.%Si. This article will describe the microstructural evolution of these alloys following HVOF spraying onto steel substrates and subsequent heat treatment. The microstructures of powders and coatings were investigated by scanning electron microscopy, and the phases were identified by x-ray diffraction. Coating microhardnesses were determined under both as-sprayed and heat-treated conditions, and by the differences related to the microstructures that developed. Finally, the wear behavior of the sprayed and heat-treated coatings in hot engine oil was measured using an industry standard test and was compared with that of previous work on a ternary alloy.

  2. Mechanical properties of Inconel 617 and 618

    SciTech Connect

    McCoy, H E; King, J F

    1985-02-01

    Inconel 617 and 618 were evaluated for application in high-temperature gas-cooled reactors (HTGRs). Techniques were developed for making sound welds, and tests were performed on base and weld metals. Specimens of both materials were aged to 20,000 h to evaluate thermal stability. Short-term tensile tests on alloy 617 showed that aging severely reduced the strain at fracture at both ambient and elevated temperatures. The impact energy at ambient temperature was severely degraded by aging. Creep tests showed that fracture occurred at 593 through 704{sup 0}C after only 1 to 2% strain, and higher strains were noted at higher temperatures. There was no detectable difference between the creep behavior in air and that in HTGR helium environments. Inconel alloy 618 had excellent stability during aging. Fracture strains in short-term tensile tests and impact energies in impact tests remained high after aging. The creep properties of alloy 618 were equivalent in air and in HTGR helium. Both alloys were carburized during creep testing in HTGR helium, and the rate of carburization became rather high at 760{sup 0}C and higher temperatures. 49 figures, 20 tables.

  3. Fatigue Behavior of Inconel 718 TIG Welds

    NASA Astrophysics Data System (ADS)

    Alexopoulos, Nikolaos D.; Argyriou, Nikolaos; Stergiou, Vasillis; Kourkoulis, Stavros K.

    2014-08-01

    Mechanical behavior of reference and TIG-welded Inconel 718 specimens was examined in the present work. Tensile, constant amplitude fatigue, and fracture toughness tests were performed in ambient temperature for both, reference and welded specimens. Microstructure revealed the presence of coarse and fine-grained heat-affected zones. It has been shown that without any post-weld heat treatment, welded specimens maintained their tensile strength properties while their ductility decreased by more than 40%. It was found that the welded specimens had lower fatigue life and this decrease was a function of the applied fatigue maximum stress. A 30% fatigue life decrease was noticed in the high cycle fatigue regime for the welded specimens while this decrease exceeded 50% in the low cycle fatigue regime. Cyclic stress-strain curves showed that Inconel 718 experiences a short period of hardening followed by softening for all fatigue lives. Cyclic fatigue response of welded specimens' exhibited cyclically stable behavior. Finally, a marginal decrease was noticed in the Mode I fracture toughness of the welded specimens.

  4. Numerical Investigation of Combustion and Flow Dynamics in a High Velocity Oxygen-Fuel Thermal Spray Gun

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoguang; Song, Qiuzhi; Yu, Zhiyi

    2016-02-01

    The combustion and flow behavior within a high velocity oxygen-fuel (HVOF) thermal spray gun is very complex and involves multiphase flow, heat transfer, chemical reactions, and supersonic/subsonic transitions. Additionally, this behavior has a significant effect on the formation of a coating. Non-premixed combustion models have been developed and are able to provide insight into the underlying physics of the process. Therefore, this investigation employs a non-premixed combustion model and the SST k - ω turbulence model to simulate the flow field of the JP5000 (Praxair-TAFA, US) HVOF thermal spray gun. The predicted temperature and velocity have a high level of agreement with experimental data when using the non-premixed combustion model. The results are focused on the fuel combustion, the subsequent gas dynamics within the HVOF gun, and the development of a supersonic free jet outside the gun. Furthermore, the oxygen/fuel inlet turbulence intensity, the fuel droplet size, and the oxygen/fuel ratio are investigated to determine their effect on the supersonic flow characteristics of the combustion gas.

  5. Application of thermal spray coatings to aerospace structures

    SciTech Connect

    Novak, H.L.

    1994-12-31

    Reusable launch vehicles located by the ocean are subject to harsh seacoast environments before launch and immersion after splashdown at sea and tow back to the refurbishment facility. The use of various thermal spray processes for depositing corrosion and erosion protective materials to the alloy substrates has potential for enhancing the corrosion/erosion resistance and useful life of those expensive large reusable aerospace structures. Thermal spray processes such as high velocity oxygen fuel (HVOF), plasma, arc spray and conventional oxygen fuel spray and the IVD process (pure aluminum only) have been used to coat test panels and scrap flight hardware with various applied materials. Pure aluminum, aluminum/aluminum oxide matrix (DURALCAN), and pure zinc have been applied over 2219-T87 aluminum alloy, 4340 steel alloy substrates. Salt spray testing has been conducted in accordance with ASTM B-117 as well as beach exposure tests at Kennedy Space Center, Florida. Adhesion tests have been performed for all materials applied to the various substrates as well as monitoring of substrate temperatures during the spray process. The pure aluminum, zinc, and aluminum/aluminum oxide matrix material afforded excellent corrosion protection in both beach exposure and salt spray environments. in conclusion, tests and actual applications have shown that the various thermal spray processes and coating materials have significant potential for enhancing corrosion/erosion resistance and extending the useful service life of expensive aerospace structures exposed to marine environments. The ability to effectively repair damaged IVD aluminum coated substrates using arc sprayed material adds flexibility to the maintenance process. Due to the excellent adhesion and corrosion protection of the substrate, tests are underway to determine if chromate conversion coating can be eliminated prior to primer/topcoat application.

  6. Increasing the Useful Life of Quench Reliefs with Inconel Bellows

    SciTech Connect

    Soyars, W. M.

    1999-01-01

    Reliable quench relief valves are an important part of superconducting magnet systems. Fermilab developed bellows-actuated cryogenic quench reliefs which have been in use since the early l 980's. The original design uses a stainless steel bellows. A high frequency, low amplitude vibration during relieving events has resulted in fatigue failures in the original design. To take advantage of the improved resistance to fatigue of Inconel, a nickel-chromium alloy, reliefs using Inconel 625 bellows were made. Design, development, and testing of the new version reliefs will be discussed. Tests show that relief valve lifetimes using Inconel bellows are more than five times greater than when using the original stainless steel bellows. Inconel bellows show great promise in increasing the lifetime of quench relief valves, and thus the reliability of accelerator cryogenic systems.

  7. Supersolidus Liquid Phase Sintering Modeling of Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Levasseur, David; Brochu, Mathieu

    2016-02-01

    Powder metallurgy of Inconel 718 superalloy is advantageous as a near-net shape process for complex parts to reduce the buy-to-fly ratio and machining cost. However, sintering Inconel 718 requires the assistance of supersolidus liquid formation to achieve near full density and involves the risk of distortion at high temperatures. The present work is focused on modeling the onset of sintering and distortion as a function of temperature, grain size, and part geometry for Inconel 718. Using experimental sintering results and data available in the literature, the supersolidus liquid phase sintering of Inconel 718 was modeled. The model was used to define a processing window where part distortion would be avoided.

  8. Theory and Apparatus for Measurement of Emissivity for Radiative Cooling of Hypersonic Aircraft with Data for Inconel and Inconel X

    NASA Technical Reports Server (NTRS)

    O'Sullivan, William J , Jr; Wade, William R

    1957-01-01

    The importance of radiation as a means of cooling high-supersonic- and hypersonic-speed aircraft is discussed to show the need for measurements of the total hemispherical emissivity of surfaces. The theory underlying the measurement of the total hemispherical emissivity of surfaces is presented, readily duplicable apparatus for performing the measurements is described, and measurements for stably oxidized Inconel and Inconel X are given for the temperature range from 600 F to 2,000 F.

  9. Application of TiC reinforced Fe-based coatings by means of High Velocity Air Fuel Spraying

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Sommer, J.

    2017-03-01

    In the field of hydraulic applications, different development trends can cause problems for coatings currently used as wear and corrosion protection for piston rods. Aqueous hydraulic fluids and rising raw material prices necessitate the search for alternatives to conventional coatings like galvanic hard chrome or High Velocity Oxygen Fuel (HVOF)-sprayed WC/Co coatings. In a previous study, Fe/TiC coatings sprayed by a HVOF-process, were identified to be promising coating systems for wear and corrosion protection in hydraulic systems. In this feasibility study, the novel High Velocity Air Fuel (HVAF)-process, a modification of the HVOF-process, is investigated using the same feedstock material, which means the powder is not optimized for the HVAF-process. The asserted benefits of the HVAF-process are higher particle velocities and lower process temperatures, which can result in a lower porosity and oxidation of the coating. Further benefits of the HVAF process are claimed to be lower process costs and higher deposition rates. In this study, the focus is set on to the applicability of Fe/TiC coatings by HVAF in general. The Fe/TiC HVAF coating could be produced, successfully. The HVAF- and HVOF-coatings, produced with the same powder, were investigated using micro-hardness, porosity, wear and corrosion tests. A similar wear coefficient and micro-hardness for both processes could be achieved. Furthermore the propane/hydrogen proportion of the HVAF process and its influence on the coating thickness and the porosity was investigated.

  10. Comparison of Oxidation and Microstructure of Warm-Sprayed and Cold-Sprayed Titanium Coatings

    NASA Astrophysics Data System (ADS)

    Kim, KeeHyun; Kuroda, Seiji; Watanabe, Makoto; Huang, RenZhong; Fukanuma, Hirotaka; Katanoda, Hiroshi

    2012-06-01

    Thick titanium coatings were prepared by the warm spraying (WS) and cold spraying (CS) processes to investigate the oxidation and microstructure of the coating layers. Prior to the coating formations, the temperature and velocity of in-flight titanium powder particles were numerically calculated. Significant oxidation occurred in the WS process using higher gas temperature conditions with low nitrogen flow rate, which is mixed to the flame jet of a high velocity oxy-fuel (HVOF) spray gun in order to control the temperature of the propellant gas. Oxidation, however, decreased strikingly as the nitrogen flow rate increased. In the CS process using nitrogen or helium as a propellant gas, little oxidation was observed. Even when scanning electron microscopy or an x-ray diffraction method did not detect oxides in the coating layers produced by WS using a high nitrogen flow rate or by CS using helium, the inert gas fusion method revealed minor increases of oxygen content from 0.01 to 0.2 wt.%. Most of the cross-sections of the coating layers prepared by conventional mechanical polishing looked dense. However, the cross-sections prepared by an ion-milling method revealed the actual microstructures containing small pores and unbounded interfaces between deposited particles.

  11. Spray automated balancing of rotors: Methods and materials

    NASA Technical Reports Server (NTRS)

    Smalley, Anthony J.; Baldwin, Richard M.; Schick, Wilbur R.

    1988-01-01

    The work described consists of two parts. In the first part, a survey is performed to assess the state of the art in rotor balancing technology as it applies to Army gas turbine engines and associated power transmission hardware. The second part evaluates thermal spray processes for balancing weight addition in an automated balancing procedure. The industry survey reveals that: (1) computerized balancing equipment is valuable to reduce errors, improve balance quality, and provide documentation; (2) slow-speed balancing is used exclusively, with no forseeable need for production high-speed balancing; (3) automated procedures are desired; and (4) thermal spray balancing is viewed with cautious optimism whereas laser balancing is viewed with concern for flight propulsion hardware. The FARE method (Fuel/Air Repetitive Explosion) was selected for experimental evaluation of bond strength and fatigue strength. Material combinations tested were tungsten carbide on stainless steel (17-4), Inconel 718 on Inconel 718, and Triballoy 800 on Inconel 718. Bond strengths were entirely adequate for use in balancing. Material combinations have been identified for use in hot and cold sections of an engine, with fatigue strengths equivalent to those for hand-ground materials.

  12. Non-Destructive Evaluation of Thermal Spray Coating Interface Quality By Eddy Current Method

    SciTech Connect

    B. Mi; G. Zhao; R. Bayles

    2006-08-10

    Thermal spray coating is usually applied through directing molten or softened particles at very high velocities onto a substrate. An eddy current non-destructive inspection technique is presented here for thermal spray coating interface quality characterization. Several high-velocity-oxy-fuel (HVOF) coated steel plates were produced with various surface preparation conditions or spray process parameters. A quad-frequency eddy current probe was used to manually scan over the coating surface to evaluate the bonding quality. Experimental results show that different surface preparation conditions and varied process parameters can be successfully differentiated by the impedance value observed from the eddy current probe. The measurement is fairly robust and consistent. This non-contact, nondestructive, easy-to-use technique has the potential for evaluating the coating quality immediately after its application so that any defects can be corrected immediately.

  13. Nondestructive Evaluation of Thermal Spray Coating Interface Quality by Eddy Current Method

    NASA Astrophysics Data System (ADS)

    Mi, Bao; Zhao, Xiaoliang (George); Bayles, Robert

    2007-03-01

    Thermal spray coating is usually applied through directing molten or softened particles at very high velocities onto a substrate. An eddy current non-destructive inspection technique is presented here for thermal spray coating interface quality characterization. Several high-velocity-oxy-fuel (HVOF) coated steel plates were produced with various surface preparation conditions or spray process parameters. A quad-frequency eddy current probe was used to manually scan over the coating surface to evaluate the bonding quality. Experimental results show that different surface preparation conditions and varied process parameters can be successfully differentiated by the impedance value observed from the eddy current probe. The measurement is fairly robust and consistent. This non-contact, nondestructive, easy-to-use technique has the potential for evaluating the coating quality immediately after its application so that any defects can be corrected immediately.

  14. Magnetic susceptibility of Inconel alloys 718, 625, and 600 at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Goldberg, Ira B.; Mitchell, Michael R.; Murphy, Allan R.; Goldfarb, Ronald B.; Loughran, Robert J.

    1990-01-01

    After a hydrogen fuel bleed valve problem on the Discovery Space Shuttle was traced to the strong magnetization of Inconel 718 in the armature of the linear variable differential transformer near liquid hydrogen temperatures, the ac magnetic susceptibility of three samples of Inconel 718 of slightly different compositions, one sample of Inconel 625, and on sample of Inconel 600 were measured as a function of temperature. Inconel 718 alloys are found to exhibit a spin glass state below 16 K. Inconel 600 exhibits three different magnetic phases, the lowest-temperature state (below 6 K) being somewhat similar to that of Inconel 718. The magnetic states of the Inconel alloys and their magnetic susceptibilities appear to be strongly dependent on the exact composition of the alloy.

  15. Effect of Heat Treatment on Wear Resistance of Nickel Aluminide Coatings Deposited by HVOF and PTA

    NASA Astrophysics Data System (ADS)

    Benegra, M.; Santana, A. L. B.; Maranho, O.; Pintaude, G.

    2015-08-01

    This study aims to compare the wear resistance of nickel aluminide coatings deposited using plasma transferred arc (PTA) and high-velocity oxygen fuel (HVOF) processes. Wear resistance was measured in rubber wheel abrasion tests. In both deposition processes, the same raw material (nickel aluminide powder) was atomized and deposited on a 316L steel plate substrate. After deposition, specimens were subjected to thermal cycling, aiming solubilization and precipitation. Coatings deposited using PTA developed different microstructures as a result of the incorporation of substrate elements. However, despite the presence of these microstructures, they performed better than coatings processed using HVOF before the heat treatment. After thermal cycling, the superficial hardness after the wear tests for both processes was similar, resulting in similar mass losses.

  16. Brazing Inconel 625 Using the Copper Foil

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Shiang; Wang, Cheng-Yen; Shiue, Ren-Kae

    2013-12-01

    Brazing Inconel 625 (IN-625) using the copper foil has been investigated in this research. The brazed joint is composed of nanosized CrNi3 precipitates and Cr/Mo/Nb/Ni quaternary compound in the Cu/Ni-rich matrix. The copper filler 50 μm in thickness is enough for the joint filling. However, the application of Cu foil 100 μm in thickness has little effect on the shear strength of the brazed joint. The specimen brazed at 1433 K (1160 °C) for 1800 seconds demonstrates the best shear strength of 470 MPa, and its fractograph is dominated by ductile dimple fracture with sliding marks. Decreasing the brazing temperature slightly decreases the shear strength of the brazed joint due to the presence of a few isolated solidification shrinkage voids smaller than 15 μm. Increasing the brazing temperature, especially for the specimen brazed at 1473 K (1200 °C), significantly deteriorates the shear strength of the joint below 260 MPa because of coalescence of isothermal solidification shrinkage voids in the joint. The Cu foil demonstrates potential in brazing IN-625 for industrial application.

  17. Quality control of thermal sprayed coatings with an optoelectric sensor

    SciTech Connect

    Rothe, H.; Brandt, O.; Kasper, A.

    1995-12-31

    This paper reports on the development of a fully optoelectronic optical sensor that has been used for investigations concerning quality control of the high velocity oxygen fuel (HVOF) flame spraying process. The authors focused on the following parameters: WoC with Co, CoCr, Ni at T < 500 C, and Cr{sub 3}C{sub 2} with Ni-Cr, Ni at T < 900 C. Until recently, there was no non-destructive testing (NDT) approach for flame spraying available, which is a major drawback for many critical applications, like in the aerospace industry. For instance, while cooling down after spraying, cracks in the coatings may occur caused by strain. Furthermore, edges may cause similar damage to the coating. The idea was to provide the flame spraying industry with a measurement technology that is applicable in the workshop, has a contactless principle of operation and is fast compared to the commonly used metallography or scanning electron microscopy. The approach is designed for use close to the process, i.e. coating morphology was not the focus of the investigations. On the contrary, they tried to extract quality related information from surface microtopography which can be obtained in a non-destructive and affordable manner. Main points covered in this paper are theoretical considerations, the operational principles and construction of the sensor head, and quantitative metrology of surface damage such as variations in rms-roughness and cracks.

  18. Influence of Bond Coats on the Microstructure and Mechanical Behaviors of HVOF-Deposited TiAlNb Coatings

    NASA Astrophysics Data System (ADS)

    Zeng, H. J.; Zhang, L. Q.; Lin, J. P.; He, X. Y.; Zhang, Y. C.; Jia, P.

    2012-12-01

    Hot dip galvanizing has been extensively employed for corrosion protection of steel structures. However, during the process of galvanization, the corrosion in molten zinc brings many problems to galvanization industry. In this study, as a material of corrosion resistance to molten zinc intended for application in Hot-dip galvanization, HVOF Ti28.15Al63.4Nb8.25Y (at.%) coatings with different bond coats (NiCr5Al, NiCoCrAlY, CoCrAlYTaSi, and NiCr80/20) were deposited onto 316L stainless steel substrate, respectively. The influences of different bond coats on HVOF Ti28.15Al63.4Nb8.25Y coatings were investigated. The results showed that bond coat had an obvious influence on improving the mechanical properties of HVOF Ti28.15Al63.4Nb8.25Y coatings. HVOF Ti28.15Al63.4Nb8.25Y coatings with NiCoCrAlY bond coat displayed the best mechanical properties. However, bond coats had no obvious effects on the microstructure, porosity, and hardness of HVOF Ti28.15Al63.4Nb8.25Y top coatings. The effects of as-received powder morphology and grain size on the characteristics of coatings were also discussed.

  19. Microstructure and properties of thermally sprayed silicon nitride-based coatings

    NASA Astrophysics Data System (ADS)

    Thiele, S.; Berger, L.-M.; Herrmann, M.; Nebelung, M.; Heimann, R. B.; Schnick, T.; Wielage, B.; Vuoristo, P.; Schnick, T.

    2002-06-01

    The preparation of thermally sprayed, dense, Si3N4-based coatings can be accomplished using composite spray powders with Si3N4 embedded in a complex oxide binder matrix. Powders with excellent processability were developed and produced by agglomeration (spray drying) and sintering. Optimization of the heat transfer into the powder particles was found to be the most decisive factor necessary for the production of dense and well-adhering coatings. In the present work, different thermal spray processes such as detonation gun spraying (DGS), atmospheric plasma spraying (APS) with axial powder injection, and high-velocity oxyfuel spraying (HVOF) were used. The coatings were characterized using optical and scanning electron microscopy (SEM), x-ray diffraction (XRD), and microhardness testing. The wear resistance was tested using a rubber wheel abrasion wear test (ASTM G65). In addition, thermoshock and corrosion resistances were determined. The microstructure and the performance of the best coatings were found to be sufficient, suggesting the technical applicability of this new type of coating.

  20. Ion-irradiation-induced hardening in Inconel 718

    NASA Astrophysics Data System (ADS)

    Hunn, J. D.; Lee, E. H.; Byun, T. S.; Mansur, L. K.

    2001-07-01

    Inconel 718 is a material under consideration for areas in the target region of the spallation neutron source (SNS), now under construction at Oak Ridge National Laboratory (ORNL) in the US. In these positions, displacement damage from protons and neutrons will affect the mechanical properties. In addition, significant amounts of helium and hydrogen will build up in the material due to transmutation reactions. Nanoindentation measurements of solution-annealed (SA) Inconel 718 specimens, implanted with Fe-, He-, and H-ions to simulate SNS target radiation conditions, have shown that hardening occurs due to ion-induced displacement damage as well as due to the build-up of helium bubbles in the irradiated layer. Precipitation-hardened (PH) Inconel 718 also exhibited hardening by helium build-up but showed softening as a function of displacement damage due to dissolution of the γ ' and γ″ precipitates.

  1. Studies on Laser Generated Ultrasonic Waves in Inconel Super Alloy

    SciTech Connect

    Pramila, T.; Shukla, Anita; Raghuram, V.

    2010-05-28

    This paper deals with the generation, characterization and analysis of ultrasonic waves generated in a thick stepped sample of inconel super alloy using Laser Based Ultrasonic Technique. Nd-YAG pulsed laser is used for ultrasonic generation while He-Ne laser is used for heterodyne detection. Ultrasonic signals are analyzed using Fourier and wavelet transforms. Here the identification and estimation of velocity of pressure waves is presented. The mechanism of pressure wave generation is discussed in brief. Laser ultrasonics studies of inconel are being reported for the first time.

  2. Graphite to Inconel brazing using active filler metal

    SciTech Connect

    King, J.F.; Baity, F.W.; Walls, J.C.; Hoffman, D.J.

    1989-01-01

    Ion cyclotron resonant frequency (ICRF) antennas are designed to supply large amounts of auxiliary heating power to fusion-grade plasmas in the Toroidal Fusion Test Reactor (TFTR) and Tore Supra fusion energy experiments. A single Faraday shield structure protects a pair of resonant double loops which are designed to launch up to 2 MW of power per loop. The shield consists of two tiers of actively cooled Inconel alloy tubes with the front tier being covered with semicircular graphite tiles. Successful operation of the antenna requires the making of high integrity bonds between the Inconel tubes and graphite tiles by brazing. This paper discusses this process.

  3. Industrial applications of thermal sprayed coatings in Venezuelan steelmaking industry

    NASA Astrophysics Data System (ADS)

    Liscano, S.; Nuñez, E.; Gil, L.; Zerpa, R.

    2013-11-01

    The metal components subjected to high temperature conditions, abrasive wear, corrosion, impact, etc.; tend to present degradation of manufacturing material, causing the failure imminent of the component. One of the alternatives to minimize or eliminate such effect is the application of ceramic coatings, which are thermal insulators and exhibit high mechanical strength. Its extreme hardness, coupled with the low friction properties and chemical stability, allowing its use in a wide variety of applications. Therefore, the following paper describes the application of thermal sprayed coatings obtained by HVOF and Plasma technologies like alternative to protect the metallic equipment in different venezuelan industrial sectors, such as to operate under aggressive conditions of service, such as the steelmaking nationals industries. This study presents applications cases of ceramic-based coatings, in order to minimize the sticking of metallic material in components of reduction reactor of FINMET® and MIDREXTM process.

  4. Corrosion Test Results for Inconel 600 vs Inconel-Stainless UG Bellows

    SciTech Connect

    Osborne, P.E.

    2002-09-11

    The Conversion Project (CP) of the Molten Salt Reactor Experiment at Oak Ridge National Laboratory (ORNL) involves converting slightly less than 40 kg of {sup 233}U to a stable form for safe storage. The operation is performed within a few vessels interconnected by valves and 1/2-in. metal tubing. During this conversion, a particularly toxic and corrosive by-product is formed, namely aqueous hydrofluoric acid (HF). The production of HF is a result of the hydrolysis of UF{sub 6} and subsequent steam treatments of UO{sub 2}F{sub 2}. For each mole of UF{sub 6} converted, 6 mol of HF are produced. The HF that forms during conversion combines with water to produce approximately 1.5 L of 33 wt % HF. As this mixture is transferred within the process system, the tubing and valves are exposed to high concentrations of HF in liquid and vapor form. Of particular concern in the system are the almost 30 valves that have the potential for exposure to HF. For these valves, a vendor-supplied UG valve was installed. UG valves consist of an Alloy 400 (Monel) body and stem tip and Alloy 600 (Inconel) bellows. These valves have been used under experimental conditions that simulate the CP. It has been established that they have a finite life when exposed to a HF and air environment. Most failures were seen around the flange at the bottom of the bellows, and it was suspected that this flange and the weld material were not Inconel. In December 2001, the vendor confirmed that this flange was not Inconel but instead was stainless steel 316. After discussions between the vendor and ORNL staff involved with the CP effort, it was decided that the entire wetted area of the bellows would be fabricated from Alloy 600. In March 2002, four newly fabricated bellows assemblies were received from the vendor for the purposes of corrosion testing in HF. This report presents results from the corrosion tests conducted to determine if the new design of the bellows would enhance their corrosion resistance.

  5. Structure characterization and wear performance of NiTi thermal sprayed coatings

    NASA Astrophysics Data System (ADS)

    Cinca, N.; Isalgué, A.; Fernández, J.; Guilemany, J. M.

    2010-08-01

    NiTi shape memory alloy (SMA) has been studied for many years for its shape memory and pseudoelastic properties, as well as its biocompatibility, which make it suitable for many biomedical applications. However, SMA NiTi is also interesting for relevant wear resistance near the transition temperature which, along with its high oxidation and corrosion resistance, suggests its use as a coating to increase the lifetime of some components. Also, whereas bulk material properties have been characterized in respect of the nominal composition, manufacturing methods and thermo-mechanical treatments, NiTi overlays have been investigated much less. Most existent works in this field specifically deal with magnetron sputtering technology for thin films and its use in micro-devices (micro-electro-mechanical systems, MEMS), just some works refer to vacuum plasma spraying (VPS) for thicker coatings. The present paper explores and compares the microstructure and wear-related properties of coatings obtained from atomized NiTi powders, by VPS as well as by atmospheric plasma spraying (APS) and high velocity oxygen fuel (HVOF) techniques. In the present case, the wear behaviour of the NiTi deposits has been studied by rubber-wheel equipment and ball-on-disk tests. The results obtained at room temperature show that the APS-quenched coatings exhibit a preferential dry sliding wear mechanism, while the VPS and HVOF coatings show an abrasive mechanism.

  6. Microstructure And Weld Cracking In Inconel 718(R)

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.

    1988-01-01

    Theories on relationship between metallurgy and microfissuring confirmed. Report describes research on effects of microstructure on cracking of heat-affected zones of welds in Inconel 718(R) alloy. In experimental studies, specimens subjected to various combinations of time-varying thermal and mechanical stresses to simulate welding conditions and to identify physical and chemical effects causing microfissuring.

  7. Microstructure And Weld Cracking In Inconel 718(R)

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.

    1988-01-01

    Theories on relationship between metallurgy and microfissuring confirmed. Report describes research on effects of microstructure on cracking of heat-affected zones of welds in Inconel 718(R) alloy. In experimental studies, specimens subjected to various combinations of time-varying thermal and mechanical stresses to simulate welding conditions and to identify physical and chemical effects causing microfissuring.

  8. Asbestos and Inconel combined to form hot-gas seal

    NASA Technical Reports Server (NTRS)

    Wooster, C. W., Jr.

    1968-01-01

    Hot-gas seal prevents warpage tendencies in large flange joints exposed to high temperatures, such as those present in large space vehicle engine exhausts. Two Inconel wire mesh cores are held in place by an asbestos cloth cover that acts as a spacer to form the seal.

  9. In-flight particle pyrometer for thermal spray processes. Final report, October 1, 1992--December 31, 1994

    SciTech Connect

    1995-02-20

    The objective of the project was to produce an industrial hardened particle temperature sensor. In general the thermal spray community believes that the particle temperature and velocity prior to impact on the substrate are two of the predominant parameters which effect coating quality. Prior to the full scale prototyping of such an instrument it was necessary to firmly establish the relationship between operating parameters, particle temperature and coating characteristics. It was shown in the first year of this project that the characteristics and consistency of the coatings formed are directly determined by particle velocity and temperature at impact. For the HVOF spray process the authors have also shown that the particle velocity is determined primarily by chamber pressure, while stoichiometry (the ratio of oxygen to fuel) has a minor influence. Hence, particle velocity can be controlled by maintaining the chamber pressure at a set point. Particle temperature, on the other hand is primarily a function of stoichiometry. Therefore particle velocity and temperature can be independently controlled. In the second year (FY-94), an industrial hardened prototype particle temperature sensor (In-flight Particle Pyrometer) was produced. The IPP is a two-color radiation pyrometer incorporating improvements which make the device applicable to the measurement of in-flight temperature of particles over a wide range of operating conditions in thermal spray processes. The device is insensitive to particulate loading (particle feed rate), particle composition, particle size distribution, and provides an ensemble average particle temperature. The sensor head is compact and coupled to the electronics via a fiber optic cable. Fiber optic coupling allows maximum flexibility of deployment while providing isolation of the electronics from electromagnetic interference and the hot, particulate laden environment of a typical spray booth. The device is applicable to all thermal spray

  10. A comparative study of high velocity oxygen fuel, vacuum plasma spray, and axial plasma spray for the deposition of CoNiCrAlY bond coat alloy

    NASA Astrophysics Data System (ADS)

    Scrivani, A.; Bardi, U.; Carrafiello, L.; Lavacchi, A.; Niccolai, F.; Rizzi, G.

    2003-12-01

    In the aerospace field as well as in the stationary gas turbine field, thermally sprayed coatings are used to improve the surface properties of nickel-super-alloys materials. Coatings are commonly used as bond coat and antioxidation materials (mainly MCrAlY alloys) and as thermal barrier coatings (mainly yttria partially stabilized zirconia). The purpose of the current study was to assess the properties of thermally sprayed bond coat CoNiCrAlY alloys comparing the performance of three different techniques: vacuum plasma spray (VPS), high velocity oxygen fuel (HVOF), and axial plasma spray (AxPS). The quality of the deposited films has been assessed and compared from the point of view of microstructural (porosity, oxide concentration, unmelted particles presence) and mechanical (hardness) characteristics. The surface composition and morphology of the coatings were also determined. Specific efficiency tests were performed for the three examined technologies. The highest quality coatings are obtained by VPS, but also high velocity oxygen fuel and AxPS sprayed films have interesting properties, which can make their use interesting for some applications.

  11. Fabrication of High-Temperature Heat Exchangers by Plasma Spraying Exterior Skins on Nickel Foams

    NASA Astrophysics Data System (ADS)

    Hafeez, P.; Yugeswaran, S.; Chandra, S.; Mostaghimi, J.; Coyle, T. W.

    2016-06-01

    Thermal-sprayed heat exchangers were tested at high temperatures (750 °C), and their performances were compared to the foam heat exchangers made by brazing Inconel sheets to their surface. Nickel foil was brazed to the exterior surface of 10-mm-thick layers of 10 and 40 PPI nickel foam. A plasma torch was used to spray an Inconel coating on the surface of the foil. A burner test rig was built to produce hot combustion gases that flowed over exposed face of the heat exchanger. Cooling air flowed through the foam heat exchanger at rates of up to 200 SLPM. Surface temperature and air inlet/exit temperature were measured. Heat transfer to air flowing through the foam was significantly higher for the thermally sprayed heat exchangers than for the brazed heat exchangers. On an average, thermally sprayed heat exchangers show 36% higher heat transfer than conventionally brazed foam heat exchangers. At low flow rates, the convective resistance is large (~4 × 10-2 m2 K/W), and the effect of thermal contact resistance is negligible. At higher flow rates, the convective resistance decreases (~2 × 10-3 m2 K/W), and the lower contact resistance of the thermally sprayed heat exchanger provides better performance than the brazed heat exchangers.

  12. Agricultural Spraying

    NASA Technical Reports Server (NTRS)

    1986-01-01

    AGDISP, a computer code written for Langley by Continuum Dynamics, Inc., aids crop dusting airplanes in targeting pesticides. The code is commercially available and can be run on a personal computer by an inexperienced operator. Called SWA+H, it is used by the Forest Service, FAA, DuPont, etc. DuPont uses the code to "test" equipment on the computer using a laser system to measure particle characteristics of various spray compounds.

  13. AF Cr(VI) Minimize Roadmap: Phase 1 Results

    DTIC Science & Technology

    2010-12-01

    HC-1 WC/CoCr, Tribaloy 400, Tribaloy 800, Cr3C2/20(80Ni-20Cr) Thermal Spray (HVOF) 1.4, 1.5, 1.10, 1.15, 1.27, 1.39, 1.64 Hard Chrome LOS Plating...Landing Gear High Strength Steel HC-1 WC/CoCr, Tribaloy 400, Cr3C2/20(80Ni-20Cr) Thermal Spray (HVOF) 1.8, 1.46, 1.15, 1.16, 1.27, 1.39, 1.64 Hard...Chrome LOS Plating Engine Components Nickel Alloys (Inconel) HC-2 WC/CoCr, Tribaloy 400, Tribaloy 800, Cr3C2/20(80Ni-20Cr) Thermal Spray (HVOF) 1.4

  14. Experimental and numerical evaluation of the performance of supersonic two-stage high-velocity oxy-fuel thermal spray (Warm Spray) gun

    NASA Astrophysics Data System (ADS)

    Katanoda, H.; Morita, H.; Komatsu, M.; Kuroda, S.

    2011-03-01

    The water-cooled supersonic two-stage high-velocity oxy-fuel (HVOF) thermal spray gun was developed to make a coating of temperature-sensitive material, such as titanium, on a substrate. The gun has a combustion chamber (CC) followed by a mixing chamber (MC), in which the combustion gas is mixed with the nitrogen gas at room temperature. The mixed gas is accelerated to supersonic speed through a converging-diverging (C-D) nozzle followed by a straight passage called the barrel. This paper proposes an experimental procedure to estimate the cooling rate of CC, MC and barrel separately. Then, the mathematical model is presented to predict the pressure and temperature in the MC for the specific mass flow rates of fuel, oxygen and nitrogen by assuming chemical equilibrium with water-cooling in the CC and MC, and frozen flow with constant specific heat from stagnant condition to the throat in the CC and MC. Finally, the present mathematical model was validated by comparing the calculated and measured stagnant pressures of the CC of the two-stage HVOF gun.

  15. Corrosion fatigue of Inconel 718 and Incoloy 903

    NASA Technical Reports Server (NTRS)

    Franklin, D. B.; Nelson, E. E.

    1981-01-01

    Corrosion fatigue tests were conducted on Inconel 718 and Incoloy 903 in distilled water, 500 ppm NaCl, and 3.5% NaCl. Results were compared to the endurance limit in air. For Inconel 718, the corrosion fatigue strength (CFS) IN 3.5% NaCl WAS 328 MPa or 75 percent of the endurance limit. For Incoloy 903, the CFS ranged from 234 MPa in distilled water (68 percent of the endurance limit) to 103 MPa in 3.5% NaCl (30 percent of the endurance limit). Results indicate that, for components which have limited fatigue life, an evaluation of the combined effects of fatigue and the corrosive atmosphere must be considered in projecting useful lifetimes.

  16. Further Study of near Solidus Intergranular Cracking in Inconel 718

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.

    1981-01-01

    A series of tests, performed to determine the strain necessary to initiate intergranular cracking in Inconel 718 as a function of temperature, contained enough scatter near the melting temperature that questions remained as to the best curve of curves to fit to the data. Fracture surface analysis showed that the scatter was due to incipient melting in the grain boundary region. The melting contributed to low fracture strain but had only a small on the incipient cracking strain. Gleeble tests, which could be interrupted by water quenching, were used to study the incipient intergranular melting of Inconel 718. This modified weld simulation test provided a sufficiently rapid quench to preserve the intergranular microstructure created during incipient melting. This structure was studied both microscopically and with energy dispensive X-ray analysis. The implications of incipient melting and low-strain incipient cracking on the development of microfissuring envelopes are discussed.

  17. Nonlinear acoustics experimental characterization of microstructure evolution in Inconel 617

    SciTech Connect

    Yao, Xiaochu; Liu, Yang; Lissenden, Cliff J.

    2014-02-18

    Inconel 617 is a candidate material for the intermediate heat exchanger in a very high temperature reactor for the next generation nuclear power plant. This application will require the material to withstand fatigue-ratcheting interaction at temperatures up to 950°C. Therefore nondestructive evaluation and structural health monitoring are important capabilities. Acoustic nonlinearity (which is quantified in terms of a material parameter, the acoustic nonlinearity parameter, β) has been proven to be sensitive to microstructural changes in material. This research develops a robust experimental procedure to track the evolution of damage precursors in laboratory tested Inconel 617 specimens using ultrasonic bulk waves. The results from the acoustic non-linear tests are compared with stereoscope surface damage results. Therefore, the relationship between acoustic nonlinearity and microstructural evaluation can be clearly demonstrated for the specimens tested.

  18. Nonlinear acoustics experimental characterization of microstructure evolution in Inconel 617

    NASA Astrophysics Data System (ADS)

    Yao, Xiaochu; Liu, Yang; Lissenden, Cliff J.

    2014-02-01

    Inconel 617 is a candidate material for the intermediate heat exchanger in a very high temperature reactor for the next generation nuclear power plant. This application will require the material to withstand fatigue-ratcheting interaction at temperatures up to 950°C. Therefore nondestructive evaluation and structural health monitoring are important capabilities. Acoustic nonlinearity (which is quantified in terms of a material parameter, the acoustic nonlinearity parameter, β) has been proven to be sensitive to microstructural changes in material. This research develops a robust experimental procedure to track the evolution of damage precursors in laboratory tested Inconel 617 specimens using ultrasonic bulk waves. The results from the acoustic non-linear tests are compared with stereoscope surface damage results. Therefore, the relationship between acoustic nonlinearity and microstructural evaluation can be clearly demonstrated for the specimens tested.

  19. Warm Spraying of High-Strength Ni-Al-Bronze: Cavitation Characteristics and Property Prediction

    NASA Astrophysics Data System (ADS)

    Krebs, Sebastian; Kuroda, Seiji; Katanoda, Hiroshi; Gaertner, Frank; Klassen, Thomas; Araki, Hiroshi; Frede, Simon

    2017-01-01

    Bronze materials such as Ni-Al-bronze show exceptional performances against cavitation erosion, due to their high fatigue strength and high strength. These materials are used for ship propellers, pump systems or for applications with alternating stresses. Usually, the respective parts are cast. With the aim to use resources more efficiently and to reduce costs, this study aimed to evaluate opportunities to apply bronze as a coating to critical areas of respective parts. The coatings should have least amounts of pores and non-bonded areas and any contaminations that might act as crack nuclei and contribute to material damages. Processes with low oxidation and high kinetic impacts fulfill these criteria. Especially warm spraying, a nitrogen-cooled HVOF process, with similar impact velocities as cold gas spraying but enhanced process temperature, allows for depositing high-strength Ni-Al-bronze. This study systematically simulates and evaluates the formation and performance of warm-sprayed Ni-Al-bronze coatings for different combustion pressures and nitrogen flow rates. Substrate preheating was used to improve coating adhesion for lower spray parameter sets. Furthermore, this study introduces an energy-based concept to compare spray parameter sets and to predict coating properties. Coatings with low porosities and high mechanical strengths are obtained, allowing for a cavitation resistance similar to bulk material.

  20. Effect of pulse duty cycle on Inconel 718 laser welds

    NASA Technical Reports Server (NTRS)

    McCay, M. H.; McCay, T. D.; Dahotre, N. B.; Sharp, C. M.; Sedghinasab, A.; Gopinathan, S.

    1989-01-01

    Crack sensitive Inconel 718 was laser pulse welded using a 3.0 kW CO2 laser. Weld shape, structure, and porosity were recorded as a function of the pulse duty cycle. Within the matrix studied, the welds were found to be optimized at a high (17 ms on, 7 ms off) duty cycle. These welds were superior in appearance and lack of porosity to both low duty cycle and CW welds.

  1. Tritium Permeability of Incoloy 800H and Inconel 617

    SciTech Connect

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2012-07-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950°C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm)—three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  2. Tritium Permeability of Incoloy 800H and Inconel 617

    SciTech Connect

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2011-09-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950 C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm) - three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  3. Creep-rupture tests of internally pressurized Inconel 702 tubes

    NASA Technical Reports Server (NTRS)

    Gumto, K. H.

    1973-01-01

    Seamless Inconel 702 tubes with 0.375-in. outside diameter and 0.025-in. wall thickness were tested to failure at temperatures from 1390 to 1575 F and internal helium pressures from 700 to 1800 psi. Lifetimes ranged from 29 to 1561 hr. The creep-rupture strength of the tubes was about 70 percent lower than that of sheet specimens. Larson-Miller correlations and photomicrographs of some specimens are presented.

  4. Growth and characterization of nanocrystalline zirconium nitride-inconel structures

    NASA Astrophysics Data System (ADS)

    Aouadi, S. M.; Maeruf, T.; Sodergren, M.; Mihut, D. M.; Rohde, S. L.; Xu, J.; Mishra, S. R.

    2005-07-01

    This paper reports on the investigation of the physical, chemical, optical, mechanical, and tribological properties of reactively sputtered zirconium nitride-inconel composite nanocrystalline mixture films. These films were co-sputtered from a Zr and an inconel targets onto Si (111) substrates at room temperature using a fixed power to the Zr target (PZr) and a fixed flow of nitrogen and argon. Two sets of samples were produced by (1) varying the power to the inconel target (Pinc) and using a fixed bias voltage Vb and (2) by varying Vb and keeping Pinc fixed. The elemental composition was deduced from x-ray photoelectron spectroscopy, and was found to be influenced by Pinc and Vb. X-ray diffraction revealed the presence of nanocrystals of ZrN with a pattern typical of the NaCl structure. The grain size was found to decrease with the increase in ``inconel'' content in the film. The optical constants were measured using spectroscopic ellipsometry and were subsequently simulated using a Drude-Lorentz model. A correlation between film structure-composition and optical constants was established. The hardness and elastic modulus of each sample were measured by nanoindentation. The hardest films were produced using a Vb=-130 V bias voltage and Pinc=4 W. Microwear measurements were carried out using positive constant normal loads and the wear tracks were imaged and processed. The measured values for the friction coefficients, residual depth of tip indentations, wear volumes, and surface roughness were reported. The lowest recorded wear volume using a load of 4 mN was 10-3 μm. Finally, the coatings were worn against ball-bearing steel using a ball-on-disk tribotester. Characterization of the wear tracks were performed by profilometry. A low wear coefficient of 1.7×10-7 mm3/s was obtained for a load of 5 N.

  5. Modeling the viscoplastic behavior of Inconel 718 at 1200 F

    NASA Technical Reports Server (NTRS)

    Abdel-Kader, M. S.; Eftis, J.; Jones, D. L.

    1988-01-01

    A large number of tests, including tensile, creep, fatigue, and creep-fatigue were performed to characterize the mechanical properties of Inconel 718 (a nickel based superalloy) at 1200 F, the operating temperature for turbine blades. In addition, a few attempts were made to model the behavior of Inconel 718 at 1200 F using viscoplastic theories. The Chaboche theory of viscoplasticity can model a wide variety of mechanical behavior, including monotonic, sustained, and cyclic responses of homogeneous, initially-isotropic, strain hardening (or softening) materials. It is shown how the Chaboche theory can be used to model the viscoplastic behavior of Inconel 718 at 1200 F. First, an algorithm was developed to systematically determine the material parameters of the Chaboche theory from uniaxial tensile, creep, and cyclic data. The algorithm is general and can be used in conjunction with similar high temperature materials. A sensitivity study was then performed and an optimal set of Chaboche's parameters were obtained. This study has also indicated the role of each parameter in modeling the response to different loading conditions.

  6. High Temperature Mechanical Properties of Free-Standing HVOF CoNiCrAlY Coatings by Lateral Compression of Circular Tube

    NASA Astrophysics Data System (ADS)

    Waki, Hiroyuki; Nakamura, Kyousuke; Yamaguchi, Itsuki; Kobayashi, Akira

    MCrAlY, M means Co and/or Ni, sprayed coating is used to protect a super alloy substrate from corrosion or oxidation in a gas turbine blade. However, the mechanical properties are not well-known, because there are few proper measurement methods for a thin coating at high temperature. Authors have developed the new easy method to measure the mechanical properties using the lateral compression of a circular tube. The method is useful to apply to a thin coating because it does not need chucking and manufacturing a test piece is very easy. The method is also easily applicable to high temperature measurement. In this study, high temperature mechanical properties, Young's modulus, bending strength and fracture strain, of CoNiCrAlY coatings by HVOF were systematically measured. The results obtained were as follows: Young's modulus and bending strength suddenly decreased beyond 400˜450°C. The Young's modulus and bending strength thermally treated at higher than 1050°C was significantly higher than that of virgin CoNiCrAlY coating. It was found that higher thermal treatment in atmosphere was the most effective in increasing the Young's modulus and bending strength. It was also found that the improvement of Young's modulus was primarily caused by not the effect of TGO but the sintering and diffusion of unfused particles. On the contrary, the fracture strain increased beyond 400°C differently from the bending strength. The fracture strains of CoNiCrAlY thermally treated in vacuum were higher than those of CoNiCrAlY treated in atmosphere. It was found that higher thermal treatment in vacuum was the most effective in increasing the fracture strain.

  7. Robot based deposition of WC-Co HVOF coatings on HSS cutting tools as a substitution for solid cemented carbide cutting tools

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Schaak, C.; Biermann, D.; Aßmuth, R.; Goeke, S.

    2017-03-01

    Cemented carbide (hard metal) cutting tools are the first choice to machine hard materials or to conduct high performance cutting processes. Main advantages of cemented carbide cutting tools are their high wear resistance (hardness) and good high temperature strength. In contrast, cemented carbide cutting tools are characterized by a low toughness and generate higher production costs, especially due to limited resources. Usually, cemented carbide cutting tools are produced by means of powder metallurgical processes. Compared to conventional manufacturing routes, these processes are more expensive and only a limited number of geometries can be realized. Furthermore, post-processing and preparing the cutting edges in order to achieve high performance tools is often required. In the present paper, an alternative method to substitute solid cemented carbide cutting tools is presented. Cutting tools made of conventional high speed steels (HSS) were coated with thick WC-Co (88/12) layers by means of thermal spraying (HVOF). The challenge is to obtain a dense, homogenous, and near-net-shape coating on the flanks and the cutting edge. For this purpose, different coating strategies were realized using an industrial robot. The coating properties were subsequently investigated. After this initial step, the surfaces of the cutting tools were ground and selected cutting edges were prepared by means of wet abrasive jet machining to achieve a smooth and round micro shape. Machining tests were conducted with these coated, ground and prepared cutting tools. The occurring wear phenomena were analyzed and compared to conventional HSS cutting tools. Overall, the results of the experiments proved that the coating withstands mechanical stresses during machining. In the conducted experiments, the coated cutting tools showed less wear than conventional HSS cutting tools. With respect to the initial wear resistance, additional benefits can be obtained by preparing the cutting edge by means

  8. Analysis and Elimination of High Temperature Notch Induced Microcrack Initiation in Inconel 718 Nickel-Based Alloy

    DTIC Science & Technology

    1989-01-01

    10) the particle will be sheared. I . . 22 B-2 APPLICATION TO INCONEL 718 ALLOY Taking an actual case of Inconel 718 alloy tested at 10000 F, the...stress static test at 1000OF on unnotched tensile specimens of inconel 718 *, show a tensile yield point of 135 ksice. This is in direct agreement with...energy distribution of solution treated* and aged**. Inconel 718 specimens that were stress rupture tested below the yield stress, at elevated

  9. High-Velocity Oxygen Fuel Thermal Spray of Fe-Based Amorphous Alloy: a Numerical and Experimental Study

    NASA Astrophysics Data System (ADS)

    Ajdelsztajn, L.; Dannenberg, J.; Lopez, J.; Yang, N.; Farmer, J.; Lavernia, E. J.

    2009-09-01

    The fabrication of dense coatings with appropriate properties using a high velocity oxygen fuel (HVOF) spray process requires an in-depth understanding of the complete gas flow field and particle behavior during the process. A computational fluid dynamics (CFD) model is implemented to investigate the gas flow behavior that occurs during the HVOF process and a simplified one-dimensional decoupled model of the in-flight thermal behavior of the amorphous Fe-based powder particles was developed and applied for three different spray conditions. The numerical results were used to rationalize the different coating microstructures described in the experimental results. Low porosity and amorphous coatings were produced using two different particle size distributions (16 to 25 μm and 25 to 53 μm). The amorphous characteristics of the powder were retained in the coating due to melting and rapid solidification in the case of very fine powder or ligaments (<16 μm) and to the fact that the crystallization temperature was not reached in the case of the large particles (16 to 53 μm).

  10. Development, Processing, and Testing of High-Performance Corrosion-Resistant HVOF Coatings

    SciTech Connect

    Farmer, J; Wong, F; Haslam, J; Estill, J; Branagan, D; Yang, N; Blue, C

    2003-08-26

    New amorphous-metal and ceramic coatings applied by the high-velocity oxy-fuel (HVOF) process may reduce the waste package materials cost of the Yucca Mountain high-level nuclear waste repository by over $4 billion (cost reduction of 27 to 42%). Two critical requirements that have been determined from design analysis are protection in brines that may evolve from the evaporative concentration of pore waters and protection for waste package welds, thereby preventing exposure to environments that might cause stress corrosion cracking (SCC). Our efforts are directed towards producing and evaluating these high-performance coatings for the development of lower cost waste packages, and will leverage a cost-effective collaboration with DARPA for applications involving marine corrosion.

  11. Mechanical properties and microstructure evaluation of powder bed fused inconel 625 nickel alloy

    SciTech Connect

    Brand, Michael J.

    2016-04-19

    The objectives of this report were to optimize and fabricate full density Inconel 625 samples using direct metal laser fusion, an additive manufacturing process; and to compare and evaluate precipitation and solid solution strengthening of Inconel 625 produced by PBF to conventional processed material.

  12. Arc spraying in China

    NASA Astrophysics Data System (ADS)

    Liu, Xianjun

    2001-03-01

    Although are spraying is not a new technique, recent development of arc spraying device systems, spray wires, research on the coating mechanism, and the dynamic behavior of spraying make it a most active thermal spray process. In China, the arc spraying technique is the most efficient way for long life corrosion protection of steel structures. In addition, the arc spraying process is widely used for renovation and surface modification of machine components, mold making for plastic products, high-temperature corrosion resistance for waterwalls of boilers, antisliding coatings, self-lubricating coatings, etc.

  13. Foliar spray banding characteristics

    Treesearch

    A.R. Womac; C.W. Smith; Joseph E. Mulrooney

    2004-01-01

    Foliar spray banding was explored as a means of reducing peticide use compared to broadcast applications. Barious geometric spray patterns and delivery angles of foliar spray bands were investigated to increase spray deposits in a crop row at a constant spray rate of 94 L/ha. Wind-free laboratory results indicated that a banded application using three 65° hollow-cone...

  14. Spray atomization and combustion

    NASA Technical Reports Server (NTRS)

    Faeth, G. M.

    1986-01-01

    New theoretical and experimental methods for studying sprays are reviewed. Common methods to analyze dilute sprays are described and used to interpret recent measurements of the structure of dilute sprays and related dispersed turbulent jets. Particle-laden jets, nonevaporating, evaporating, and combusting sprays, and noncondensing and condensing bubbly jets are examined and used to initially evaluate current analytical methods for a wide range of conditions. Dense sprays are briefly discussed.

  15. On Electro Discharge Machining of Inconel 718 with Hollow Tool

    NASA Astrophysics Data System (ADS)

    Rajesha, S.; Sharma, A. K.; Kumar, Pradeep

    2012-06-01

    Inconel 718 is a nickel-based alloy designed for high yield, tensile, and creep-rupture properties. This alloy has been widely used in jet engines and high-speed airframe parts in aeronautic application. In this study, electric discharge machining (EDM) process was used for machining commercially available Inconel 718. A copper electrode with 99.9% purity having tubular cross section was employed to machine holes of 20 mm height and 12 mm diameter on Inconel 718 workpieces. Experiments were planned using response surface methodology (RSM). Effects of five major process parameters—pulse current, duty factor, sensitivity control, gap control, and flushing pressure on the process responses—material removal rate (MRR) and surface roughness (SR) have been discussed. Mathematical models for MRR and SR have been developed using analysis of variance. Influences of process parameters on tool wear and tool geometry have been presented with the help of scanning electron microscope (SEM) micrographs. Analysis shows significant interaction effect of pulse current and duty factor on MRR yielding a wide range from 14.4 to 22.6 mm3/min, while pulse current remains the most contributing factor with approximate changes in the MRR and SR of 48 and 37%, respectively, corresponding to the extreme values considered. Interactions of duty factor and flushing pressure yield a minimum surface roughness of 6.2 μm. The thickness of the sputtered layer and the crack length were found to be functions of pulse current. The hollow tool gets worn out on both the outer and the inner edges owing to spark erosion as well as abrasion due to flow of debris.

  16. Diffusion of Hydrogen and Helium in Inconel 625

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Gillies, D.; Lehoczky, S.

    2006-01-01

    Diffusion parameters for hydrogen and helium in Inconel 625 were investigated. The dependence of permeability of hydrogen in the temperature range 310 - 750 C is given. Solubility of hydrogen at 1 atm in the range 640 - 860 C was determined and diffusivity of the gas was calculated. Experiments with diffusion and solubility at 0.09 atm suggest a molecular mechanism of solution of hydrogen in the material. Diffusivity of helium was estimated at less than 10(exp -18) sq cm/s (at 1040 C).

  17. Diffusion of Hydrogen and Helium in Inconel 625

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Gillies, D.; Lehoczky, S.

    2006-01-01

    Diffusion parameters for hydrogen and helium in Inconel 625 were investigated. The dependence of permeability of hydrogen in the temperature range 310 - 750 C is given. Solubility of hydrogen at 1 atm in the range 640 - 860 C was determined and diffusivity of the gas was calculated. Experiments with diffusion and solubility at 0.09 atm suggest a molecular mechanism of solution of hydrogen in the material. Diffusivity of helium was estimated at less than 10(exp -18) sq cm/s (at 1040 C).

  18. Characterization of Strain-Induced Precipitation in Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Calvo, Jessica; Penalva, Mariluz; Cabrera, José María

    2016-08-01

    Inconel 718 presents excellent mechanical properties at high temperatures, as well as good corrosion resistance and weldability. These properties, oriented to satisfy the design requirements of gas turbine components, depend on microstructural features such as grain size and precipitation. In this work, precipitation-temperature-time diagrams have been derived based on a stress relaxation technique and the characterization of precipitates by scanning electron microscopy. By using this methodology, the effect of strain accumulation during processing on the precipitation kinetics can be determined. The results show that the characteristics of precipitation are significantly modified when plastic deformation is applied, and the kinetics are slightly affected by the amount of total plastic deformation.

  19. Mean stress effects in biaxial fatigue of Inconel 718

    SciTech Connect

    Socie, D.F.; Shield, T.W.

    1984-07-01

    Biaxial fatigue tests were conducted on Inconel 718 thin-walled tubular specimens to quantify the effect of mean stress. The specimens were loaded in combined tension and torsion in strain control at room temperature. Fatigue lives ranged from 3000 to 15,000 cycles depending on the mean stress. These data were correlated with a parameter based on the maximum plastic shear strain amplitude, normal strain amplitude and mean normal stress on the plane of maximum shear strain amplitude. This parameter was combined with the Coffin-Manson equation for estimating fatigue lives. Observations of the cracking behavior show that mean stress affects the rate of crack growth and distribution of cracks.

  20. Thermal Decomposition of Some Linear Perfluoroalkanes in an Inconel Tube

    NASA Technical Reports Server (NTRS)

    Fielder, W. L.

    1961-01-01

    The products of the pyrolysis reactions of perfluoropropane, perfluoroethane, and carbon tetrafluoride in an Inconel bomb are described. The values for the energy of activation and frequency factor for the first-order pyrolysis reactions are respectively: (1) 80 kcal. per mole and 2x10(exp14) sec.(exp-1) for perfluoropropane; (2) 53 kcal. per mole and 3x10(exp7) sec.(exp-1) for perfluoroethane; and (3) 96 kcal. per mole and 4x10(exp13) sec.(exp-1) for carbon tetrafluoride.

  1. Characterization of microstructures and mechanical properties of Inconel 617/310 stainless steel dissimilar welds

    SciTech Connect

    Shah Hosseini, H. Shamanian, M.; Kermanpur, A.

    2011-04-15

    The microstructure and mechanical properties of Inconel 617/310 austenitic stainless steel dissimilar welds were investigated in this work. Three types of filler materials, Inconel 617, Inconel 82 and 310 austenitic stainless steels were used to obtain dissimilar joint using the gas tungsten arc welding process. Microstructural observations showed that there was no evidence of any possible cracking in the weldments achieved by the nickel-base filler materials. The welds produced by 617 and 310 filler materials displayed the highest and the lowest ultimate tensile strength and total elongation, respectively. The impact test results indicated that all specimens exhibited ductile fracture. Among the fillers, Inconel 617 exhibited superlative fracture toughness (205 J). The mechanical properties of the Inconel 617 filler material were much better than those of other fillers. - Research Highlights: {yields} A fine dendritic structure was seen for the Inconel 617 weld metal. {yields} A number of cracks were initiated when the 310 SS filler metal was used. {yields} All welded samples showed ductile fracture. {yields} The Inconel 617 filler material presents the optimum mechanical properties.

  2. Selective laser melting of Inconel super alloy-a review

    NASA Astrophysics Data System (ADS)

    Karia, M. C.; Popat, M. A.; Sangani, K. B.

    2017-07-01

    Additive manufacturing is a relatively young technology that uses the principle of layer by layer addition of material in solid, liquid or powder form to develop a component or product. The quality of additive manufactured part is one of the challenges to be addressed. Researchers are continuously working at various levels of additive manufacturing technologies. One of the significant powder bed processes for met als is Selective Laser Melting (SLM). Laser based processes are finding more attention of researchers and industrial world. The potential of this technique is yet to be fully explored. Due to very high strength and creep resistance Inconel is extensively used nickel based super alloy for manufacturing components for aerospace, automobile and nuclear industries. Due to law content of Aluminum and Titanium, it exhibits good fabricability too. Therefore the alloy is ideally suitable for selective laser melting to manufacture intricate components with high strength requirements. The selection of suitable process for manufacturing for a specific component depends on geometrical complexity, production quantity, and cost and required strength. There are numerous researchers working on various aspects like metallurgical and micro structural investigations and mechanical properties, geometrical accuracy, effects of process parameters and its optimization and mathematical modeling etc. The present paper represents a comprehensive overview of selective laser melting process for Inconel group of alloys.

  3. Structural Performance of Inconel 625 Superalloy Brazed Joints

    NASA Astrophysics Data System (ADS)

    Chen, Jianqiang; Demers, Vincent; Cadotte, Eve-Line; Turner, Daniel; Bocher, Philippe

    2017-02-01

    The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints under various lap distance-to-thickness ratios. The fatigue crack initiation and crack growth modes were examined via metallographic analysis, and the effect of local stress on fatigue life was assessed by finite element simulations. The fatigue results show that fatigue strength and endurance limit increase with overlap distance, leading to a relatively large scatter of results. Fatigue cracks nucleated in the high-stressed region of the weld fillets from brittle eutectic phases or from internal brazing cavities. The present work proposes to rationalize the results by using the local stress at the brazing fillet. When using this local stress, all fatigue-obtained results find themselves on a single S- N curve, providing a design curve for any joint configuration in fatigue solicitation.

  4. Surface Integrity of Inconel 718 by Ball Burnishing

    NASA Astrophysics Data System (ADS)

    Sequera, A.; Fu, C. H.; Guo, Y. B.; Wei, X. T.

    2014-09-01

    Inconel 718 has wide applications in manufacturing mechanical components such as turbine blades, turbocharger rotors, and nuclear reactors. Since these components are subject to harsh environments such as high temperature, pressure, and corrosion, it is critical to improve the functionality to prevent catastrophic failure due to fatigue or corrosion. Ball burnishing as a low plastic deformation process is a promising technique to enhance surface integrity for increasing component fatigue and corrosion resistance in service. This study focuses on the experimental study on surface integrity of burnished Inconel 718. The effects of burnishing ball size and pressure on surface integrity factors such as surface topography, roughness, and hardness are investigated. The burnished surfaces are smoother than the as-machined ones. Surface hardness after burnishing is higher than the as-machined surfaces, but become stable over a certain burnishing pressure. There exists an optimal process space of ball sized and burnishing pressure for surface finish. In addition, surface hardness after burnishing is higher than the as-machined surfaces, which is confirmed by statistical analysis.

  5. Structure-Property Correlations in Microwave Joining of Inconel 718

    NASA Astrophysics Data System (ADS)

    Bansal, Amit; Sharma, Apurbba Kumar; Kumar, Pradeep; Das, Shantanu

    2015-09-01

    The butt joining of Inconel 718 plates at 981°C solution treated and aged (981STA) condition was carried out using the microwave hybrid heating technique with Inconel 718 powder as a filler material. The developed joints were free from any microfissures (cracks) and were metallurgically bonded through complete melting of the powder particles. The as-welded joints were subjected to postweld heat treatments, including direct-aged, 981STA and 1080STA. The microstructural features of the welded joints were investigated using a field emission-scanning electron microscope equipped with x-ray elemental analysis. Microhardness and room-temperature tensile properties of the welded joints were evaluated. The postweld heat-treated specimens exhibited higher microhardness and tensile strength than the as-welded specimens due to the formation of strengthening precipitates in the microstructure after postweld heat treatments. The microhardness of the fusion zone of the joint in 1080STA condition was higher than all welded conditions due to the complete dissolution of Laves phase after 1080STA treatment. However, the tensile strength of the welded specimen in 981STA condition was higher than all welded conditions. The tensile strength in 1080STA condition was lower than that in 981STA condition because of the grain coarsening that took place after 1080STA condition. The fractography of the fractured surfaces was carried out to determine the structure-property-fracture correlation.

  6. Structural Performance of Inconel 625 Superalloy Brazed Joints

    NASA Astrophysics Data System (ADS)

    Chen, Jianqiang; Demers, Vincent; Cadotte, Eve-Line; Turner, Daniel; Bocher, Philippe

    2016-12-01

    The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints under various lap distance-to-thickness ratios. The fatigue crack initiation and crack growth modes were examined via metallographic analysis, and the effect of local stress on fatigue life was assessed by finite element simulations. The fatigue results show that fatigue strength and endurance limit increase with overlap distance, leading to a relatively large scatter of results. Fatigue cracks nucleated in the high-stressed region of the weld fillets from brittle eutectic phases or from internal brazing cavities. The present work proposes to rationalize the results by using the local stress at the brazing fillet. When using this local stress, all fatigue-obtained results find themselves on a single S-N curve, providing a design curve for any joint configuration in fatigue solicitation.

  7. Field assisted hot pressing of sintering Inconel 718 MIM samples

    NASA Astrophysics Data System (ADS)

    Dugauguez, Olivier; Torralba, Jose Manuel; Barriere, Thierry; Gelin, Jean-Claude

    2016-10-01

    In this investigation on samples obtained by Metal Injection Molding (MIM), the conventional way of sintering in a furnace will be compared to Field Assisted Hot pressing (FAHP) sintering. The difficulty of this method is to be able to control the shrinkage of the sample and so its shape. It has yet not been investigated with a super alloy powder and so, the effects of a high sintering rate. By accelerating the sintering kinetics, the thermal behavior may be modified. Hence, the behavior of the Inconel 718 sintered by FAHP has been investigated. The sintered samples were all injected from a feedstock composed of a fine particle Inconel powder and a binder principally composed of Cellulose Acetate Butyrate CAB and Poly-Ethylene Glycol PEG. The effects of the two methods on the microstructure and the mechanical properties are then compared. There was no difference in distribution of pores between the conventional sintering and the FAHP sintering but a finer grain size showed better hardness.

  8. Ultra-high temperature mechanical performance of INCONEL 690

    NASA Astrophysics Data System (ADS)

    Venkatesh, Vasisht

    The elevated temperature mechanical performance of INCONEL 690 at ultra-high temperatures (0.6-0.9 of alloy melting temperature, Tsb{m}) has been investigated to assess the underlying deformation mechanisms and develop a new life prediction methodology. In the first part of the investigation the hardening response of INCONEL 690 during tensile deformation between 200{-}1200sp°C was examined. Analysis of these results suggests that, dependent on deformation temperature, the hardening behavior of INCONEL 690 can be described by the Bodner-Partom (B-P) or Kocks-Mecking (K-M) dislocation-dislocation interaction and/or by a modified K-M dislocation-periodic barrier interaction model. Transmission electron microscopy (TEM) confirmed the presence of this hardening transition from one associated with dislocation tangle formation at low temperatures, i.e., 200{-}600sp°C, to periodically spaced dislocation walls forming parallelogram cell structures at intermediate temperatures and high stresses, i.e., 650{-}700sp°C, and at higher temperatures 750{-}1200sp°C. The elevated temperature creep behavior of INCONEL 690 has been examined from 900 to 1200sp°C\\ (0.7{-}0.9\\ Tsb{m}) at constant stresses between 6 to 33 MPa (sigma/mu = 1.5 × 10sp{-4} to 9.5 × 10sp{-4}). Two complimentary strain-time responses were observed. A normal strain-time response, characterized by decreasing creep rate with increasing time until steady state, was observed under all normalized stresses at 900sp°C. Under these conditions creep deformation was associated with intragranular dislocation climb and glide. A second periodic oscillatory strain-time response was observed at higher temperatures, 1050{-}1200sp°C, and intermediate to low stresses, sigma/mu = 1.65 × 10sp{-4}{-}4.5 × 10sp{-4}. Under these conditions repetitive grain boundary sliding and migration controlled creep deformation. The last part of the study involved the development of a design methodology for life prediction at ultra

  9. Effect of Frequency on Fatigue Crack Growth Rate of Inconel 718 at High Temperature

    DTIC Science & Technology

    1987-06-01

    Potential 6 and Displacement Measurements. 2 Fractured Specimens of Inconel 718 Showing 13 Different Cracking*Regions Corresponding to Test Under Different...Conditions. 3 Typical a vs N Experimental Data with the 16 Fitted Linear Regression Line. 4 Fatigue Crack Growth Rate (da/dN) for 17 Inconel 718 as a...Temperature Air Data are Given. 5 Time Rate of Crack Growth, (da/dt) for 18 Inconel 718 as a Function of Frequency at Kmax = 40 MPa-ml/ 2 , R = 0.1

  10. Hair spray poisoning

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002705.htm Hair spray poisoning To use the sharing features on this page, please enable JavaScript. Hair spray poisoning occurs when someone breathes in (inhales) ...

  11. Triamcinolone Nasal Spray

    MedlinePlus

    ... itchy nose and itchy, watery eyes caused by hay fever or other allergies. Triamcinolone nasal spray should not ... germs.Triamcinolone nasal spray controls the symptoms of hay fever and allergies but does not cure these conditions. ...

  12. Azelastine Nasal Spray

    MedlinePlus

    ... and replace with the pump unit. Prime the delivery system (pump unit) with four sprays or until a fine mist appears. If 3 days or more have elapsed since your last use of the nasal spray, reprime the pump with two sprays or until a fine mist appears.

  13. Remotely controlled spray gun

    NASA Technical Reports Server (NTRS)

    Cunningham, William C. (Inventor)

    1987-01-01

    A remotely controlled spray gun is described in which a nozzle and orifice plate are held in precise axial alignment by an alignment member, which in turn is held in alignment with the general outlet of the spray gun by insert. By this arrangement, the precise repeatability of spray patterns is insured.

  14. Abrasive wear of high velocity oxygen fuel (HVOF) superalloy coatings under vibration load

    NASA Astrophysics Data System (ADS)

    Kandeva, M.; Ivanova, B.; Karastoyanov, D.; Grozdanova, T.; Assenova, E.

    2017-02-01

    The present paper considers wear of coatings deposited by HVOF (High velocity oxy-fuel) technology, under conditions of dry friction against abrasive surface accompanied with the action of vibrations perpendicular to the sliding axis. Results are obtained with four type coatings: two types with Ni matrix of composition 602P – without preliminary heating of the basic surface (the substrate) and after substrate heating up to 650°C in a chamber; coating WC-12Co with tungsten matrix and coating obtained by 1:1 proportion powder mixture of both compositions 602P and WC-12Co. Results about the thickness, hardness and coating’ morphology are presented, as well as dependences of the wear and the relative wear resistance on vibration speeds in the interval 3.03 to 21.08 mm/s. New results are obtained about the nonlinear relationship between abrasive wear and vibration speed showing minimal wear for all specimens by 6.04 mm/s. It is found that lowest wear shows WC-12Co coating in the entire interval of vibration speed variation: 3.03 to 21.08 mm/s. The obtained results are new in the literature; they are not presented and published by the authors.

  15. Characterization of sprays

    NASA Technical Reports Server (NTRS)

    Chigier, N.; Mao, C.-P.

    1984-01-01

    It is pointed out that most practical power generation and propulsion systems involve the burning of different types of fuel sprays, taking into account aircraft propulsion, industrial furnaces, boilers, gas turbines, and diesel engines. There has been a lack of data which can serve as a basis for spray model development and validation. A major aim of the present investigation is to fill this gap. Experimental apparatus and techniques for studying the characteristics of fuel sprays are discussed, taking into account two-dimensional still photography, cinematography, holography, a laser diffraction particle sizer, and a laser anemometer. The considered instruments were used in a number of experiments, taking into account three different types of fuel spray. Attention is given to liquid fuel sprays, high pressure pulsed diesel sprays, and coal-water slurry sprays.

  16. Thermal-mechanical fatigue crack growth in Inconel X-750

    NASA Technical Reports Server (NTRS)

    Marchand, N.; Pelloux, R. M.

    1985-01-01

    Thermal-mechanical fatigue crack growth (TMFCG) was studied in a 'gamma-gamma' nickel base superalloy Inconel X-750 under controlled load amplitude in the temperature range from 300 to 650 C. In-phase (T sub max at sigma sub max), out-of-phase (T sub min at sigma sub max), and isothermal tests at 650 C were performed on single-edge notch bars under fully reversed cyclic conditions. A dc electrical potential method was used to measure crack length. The electrical potential response obtained for each cycle of a given wave form and R value yields information on crack closure and crack extension per cycle. The macroscopic crack growth rates are reported as a function of delta k and the relative magnitude of the TMFCG are discussed in the light of the potential drop information and of the fractographic observations.

  17. Thermal-mechanical fatigue crack growth in Inconel X-750

    NASA Technical Reports Server (NTRS)

    Marchand, N.; Pelloux, R. M.

    1984-01-01

    Thermal-mechanical fatigue crack growth (TMFCG) was studied in a gamma-gamma' nickel base superalloy Inconel X-750 under controlled load amplitude in the temperature range from 300 to 650 C. In-phase (T sub max at sigma sub max), out-of-phase (T sub min at sigma sub max), and isothermal tests at 650 C were performed on single-edge notch bars under fully reversed cyclic conditions. A dc electrical potential method was used to measure crack length. The electrical potential response obtained for each cycle of a given wave form and R value yields information on crack closure and crack extension per cycle. The macroscopic crack growth rates are reported as a function of delta k and the relative magnitude of the TMFCG are discussed in the light of the potential drop information and of the fractographic observations.

  18. The effect of laser pulse tailored welding of Inconel 718

    NASA Technical Reports Server (NTRS)

    Mccay, T. Dwayne; Mccay, Mary Helen; Sharp, C. Michael; Womack, Michael G.

    1990-01-01

    Pulse tailored laser welding has been applied to wrought, wrought grain grown, and cast Inconel 718 using a CO2 laser. Prior to welding, the material was characterized metallographically and the solid state transformation regions were identified using Differential Scanning Calorimetry and high temperature x-ray diffraction. Bead on plate welds (restrained and unrestrained) were then produced using a matrix of pulse duty cycles and pulsed average power. Subsequent characterization included heat affected zone width, penetration and underbead width, the presence of cracks, microfissures and porosity, fusion zone curvature, and precipitation and liquated region width. Pedigree welding on three selected processing conditions was shown by microstructural and dye penetrant analysis to produce no microfissures, a result which strongly indicates the viability of pulse tailored welding for microfissure free IN 718.

  19. Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740

    SciTech Connect

    Ludtka, G.M.; Smith, G.

    2007-11-19

    In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.

  20. Pulsed laser-assisted machining of Inconel 718 superalloy

    NASA Astrophysics Data System (ADS)

    Azhdari Tadavani, Soheila; Shoja Razavi, Reza; Vafaei, Reza

    2017-01-01

    Nickel-based superalloys including Inconel 718(IN718) are widely used in aerospace industries due to their superior high temperature strength, toughness, and corrosion resistance. These alloys are difficult to machine mainly because of their low thermal conductivity and high work hardening rate, which cause steep temperature gradient and high cutting forces at the tool edge. The application of laser assisted machining is the subject of many new researches since shear forces; surface coarsening and tool wear are reduced. The aim of this investigation was to evaluate laser assisted machining behavior of a 718 Inconel superalloy from the view point of machining specific energy, surface roughness, tool wear and chip appearance. Experimental apparatuses used included optical and scanning electron microscopy, spark emission spectroscopy, and EDS analysis. The results indicated that increasing the temperature to about 540 °C just ahead of primary shear zone, can result in 35% reduction of machining specific energy, in comparison with conventional machining. Furthermore, surface coarsening and tool wear were reduced by 22% and 23% respectively. Flank wear was the main deteriorating factor on cutting tools during laser assisted machining. SEM micrographs indicated that increase in temperature has no noticeable effect on finished workpiece surface. Analysis of variance obtained from regression analysis indicated that frequency of laser beam has the most influential effect on temperature. The optimum conditions for laser assisted machining of 718 superalloy is suggested as follows: 80 Hz frequency, 400 W power, 24 m/min cutting speed, and 0.052 mm/rev feed rate along with 540 °C temperature, 2.51 J/mm2 machining specific energy and 130 N cutting force.

  1. Effects of Internal and External Hydrogen on Inconel 718

    NASA Technical Reports Server (NTRS)

    Walter, R. J.; Frandsen, J. D.

    1999-01-01

    Internal hydrogen embrittlement (IHE) and hydrogen environment embrittlement (HEE) tensile and bend crack growth tests were performed on Inconel 718. For the IHE tests, the specimens were precharged to approximately 90 ppm hydrogen by exposure to 34.5 MPa H2 at 650 C. The HEE tests were performed in 34.5 MPa H2. Parameters evaluated were test temperature, strain rate for smooth and notch specimen geometries. The strain rate effect was very significant at ambient temperature for both IHE and HEE and decreased with increasing temperatures. For IHE, the strain rate effect was neglible at 260'C, and for HEE the strain rate effect was neglible at 400 C. At low temperatures, IHE was more severe than HEE, and at high temperatures HEE was more severe than IHE with a cross over temperature about 350 C. At 350 C, the equilibrium hydrogen concentration in Inconel 718 is about 50% lower than the hydrogen content of the precharged IHE specimens. Dislocation hydrogen sweeping of surface absorbed hydrogen was the likely transport mechanism for increasing the hydrogen concentration in the HEE tests sufficiently to produce the same degree of embrittlement as that of the more highly hydrogen charged IHE specimens. The main IHE fracture characteristic was formation of large, brittle flat facets, which decreased with increasing test temperature. The IHE fracture matrix surrounding the large facets ranged between brittle fine faceted to microvoid ductility depending upon strain rate, specimen geometry as well as temperature. The HEE fractures were characteristically fine featured, transgranular and brittle with a significant portion forming a "saw tooth" crystallographic pattern. Both IHE and HEE fractures were predominantly along the {1 1 1) slip and twin boundaries. With respect to embrittlement mechanism, it was postulated that dislocation hydrogen sweeping and hydrogen enhanced localized plasticity were active in HEE and IHE for concentrating hydrogen along (1 1 1) slip and twin

  2. Microstructure and properties of laser-borided Inconel 600-alloy

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Dziarski, P.; Makuch, N.; Piasecki, A.; Miklaszewski, A.

    2013-11-01

    Nickel-based superalloys are used extensively for a variety of industrial applications involving high temperatures and aggressive environments. However, under conditions of appreciable mechanical wear (adhesive or abrasive), these materials have to be distinguished by suitable wear protection. The diffusion boronizing is the thermo-chemical treatment, which improves the tribological properties of nickel and its alloys. Nevertheless, the long duration of this process is necessary in order to obtain the layers of the thickness up to about 100 μm. Instead of the diffusion process, in this study the laser boriding is used for producing boride layer on Inconel 600-alloy. During the laser alloying, the external cylindrical surface of base material is coated by paste, including amorphous boron. Then the surface is re-melted by a laser beam. The high overlapping of multiple laser tracks (86%) causes the formation of uniform laser-alloyed layer in respect of the thickness. Laser re-melted zone, heat-affected zone and the substrate characterize the microstructure. In the re-melted zone, the three areas are observed: compact borides zone consisting of nickel, chromium and iron borides (close to the surface), zone of increased percentage of Ni-Cr-Fe-matrix (appearing in the greater distance from the surface) and zone of dominant Ni-Cr-Fe-matrix percentage (at the end of the layer). The hardness obtained is comparable to that-obtained in case of diffusion boriding. Simultaneously, the laser-borided layers are significantly thicker (about 346 or 467 μm depending on the laser power used). The significant increase in their abrasive wear resistance is observed. The wear intensity factors, as well as the relative mass loss of the laser-borided samples, are ten times smaller in comparison with untreated Inconel 600-alloy.

  3. Corrosion behavior of Inconel 690 and 693 in an iron phosphate melt

    NASA Astrophysics Data System (ADS)

    Zhu, Dongmei; Kim, Cheol-Woon; Day, Delbert E.

    2005-01-01

    The corrosion resistance of Inconel 690 and 693 coupons submerged in an iron phosphate melt has been investigated. After 155 days in an iron phosphate melt at 1050 °C, which contained 30 wt% of a simulated low activity waste (LAW at Hanford), the weight loss of Inconel 690 and 693 was 14% and 8%, respectively. The overall corrosion rate, calculated from the initial and final dimensions of each coupon, was 1.3 and 0.7 μm/day for the Inconel 690 and 693, respectively. Scanning electron microscopy and X-ray diffraction of the submerged Inconel coupons after 155 days in the iron phosphate melt showed that an altered surface layer had formed which was depleted in nickel and consisted of a (Fe, Cr) 2O 3 solid solution. This altered layer appears to be chemically protective as indicated by the gradual reduction in weight loss which occurred with time in the iron phosphate melt. Inconel 693 appears to be a better candidate to use as an electrode in iron phosphate melts since its corrosion rate and weight loss was only about one half that of Inconel 690.

  4. Non-Destructive Evaluation of Thermal Spray Coating Interface Quality by Eddy Current Method

    SciTech Connect

    B.Mi; X. Zhao; R. Bayles

    2006-05-26

    Thermal spray coating is usually applied through directing molten or softened particles at very high velocities onto a substrate. An eddy current non-destructive inspection technique is presented here for thermal spray coating interface quality characterization. Several high-velocity-oxy-fuel (HVOF) coated steel plates were produced with different surface preparation conditions before applying the coating, e.g., grit-blasted surface, wire-brush cleaned surface, and a dirty surface. A quad-frequency eddy current probe was used to manually scan over the coating surface to evaluate the bonding quality. Experimental results show that the three surface preparation conditions can be successfully differentiated by looking into the impedance difference observed from the eddy current probe. The measurement is fairly robust and consistent. More specimens are also prepared with variations of process parameters, such as spray angle, stand-off distance, and application of corrosion protective sealant, etc. They are blindly tested to evaluate the reliability of the eddy current system. Quantitative relations between the coating bond strength and the eddy current response are also established with the support of destructive testing. This non-contact, non-destructive, easy to use technique has the potential for evaluating the coating quality immediately after its application so that any defects can be corrected immediately.

  5. Parameters Influencing the Photocatalytic Activity of Suspension-Sprayed TiO2 Coatings

    NASA Astrophysics Data System (ADS)

    Toma, Filofteia-Laura; Berger, Lutz-Michael; Shakhverdova, Irina; Leupolt, Beate; Potthoff, Annegret; Oelschlägel, Kathrin; Meissner, Tobias; Gomez, José Antonio Ibáñez; de Miguel, Yolanda

    2014-10-01

    Photocatalytic properties of titania have been studied very intensively for a variety of applications, including air and water purification. In order to clarify the influence of the phase composition and other parameters, thermal spraying with suspensions was applied to produce photocatalytically active titania coatings starting from two commercially available anatase and rutile submicron powders. Aqueous suspensions containing 40% solids by weight were sprayed with an HVOF process using ethylene as the fuel gas. The spray parameters were chosen in order to produce mechanically stable coatings and to preserve a high content of the initial crystalline phases of the powders. The coating microstructures, phase compositions, and surface properties were characterized. The photocatalytic performance was evaluated by degradation of the pink dye Rhodamine B (RB) using two techniques: degradation of an aqueous solution of RB and discoloration of impregnated RB. All the coatings exhibited photocatalytic activity to varying degrees, depending on the phase composition as well as other factors, namely, the coating microstructure, surface morphology, surface hydroxylation, light absorption, and interaction with the pollutant.

  6. Effects of HVOF Process Parameters on the Properties of Ni-Cr Coatings

    NASA Astrophysics Data System (ADS)

    Saaedi, J.; Coyle, T. W.; Arabi, H.; Mirdamadi, S.; Mostaghimi, J.

    2010-03-01

    This research examined the influence of processing parameters on the structure of a Ni-50Cr coating applied by high-velocity oxy-fuel spraying onto stainless steel specimens. This type of coating is normally used as protection against heat and corrosion encountered in power plant and marine boilers, and oil refinery heaters. A statistical design of experiments identified fuel and oxygen flow rates and spraying distance as the most influential parameters controlling the in-flight characteristics of the powder particles prior to impact. The effects of these parameters on the porosity level, oxide content, and microhardness of the coatings were then investigated in more detail. These results indicated that the oxide content and hardness of the coatings were dependent on the gas combustion ratio but not on spraying distance. The porosity level and amount of unmelted particles were reduced at the longest spraying distance.

  7. An Investigation of Spalling Behavior of High Velocity Oxygen Fuel (HVOF) Coatings on the 4340 Steel and HyTuf

    DTIC Science & Technology

    2007-11-02

    J.•tAM I 170 -0.33 132.1 -44 20 AOU 0MM •V#OJ?1 U&.L & M ND J 180 -0.33 139.8 -46.6 20 am 10 -0.33 147.8 -492 20 cm *7mm-I-- J21 AAPPN.TODIXELAD 21...1 134.2 -134.2 20 A1Au NA.TOW x Mm c-a 1, 4, AMA 180 .1 142.1 .142.1 2 SPECIMEN HVOF 16 OUTSIDE DIAMETER (In.): 2.3 EFFECTIVE OUTSIDE DIAMETER (In

  8. Supersonic Particle Deposition (Cold Spray)

    DTIC Science & Technology

    2006-01-26

    SUPPLEMENTARY NOTES 26th Replacement of Hard Chrome and Cadmium Plating Program Review Meeting, January 24-26, 2006, San Diego, CA. Sponsored by SERDP...Spray Cu-W ( clad powder) 197 89-90 HRB Cold Spray Ta 256 21 HRC Cold Spray Ni 403 40-41 HRC Hardness of Various Cold Spray Coatings -Cold Spray

  9. Bear Spray Safety Program

    USGS Publications Warehouse

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  10. Numerical Investigation of High Velocity Suspension Flame Spraying

    NASA Astrophysics Data System (ADS)

    Taleby, M.; Hossainpour, S.

    2012-12-01

    High-velocity suspension flame spraying (HVSFS) has recently developed as a possible alternative to conventional HVOF-spraying employing liquid suspensions instead of dry powder feedstock enables the use of nanoparticles. From the fluid dynamics point of view, the HVSFS system is complex and involves three-phase (gas, liquid and solid particles) turbulent flow, heat transfer, evaporation of the suspension solvent, chemical reactions of main fuel (propane) and suspension solvent (ethanol) and supersonic/subsonic flow transitions. Computational fluid dynamic techniques were carried out to solve the mass, momentum, and energy conservation equations. The realizable k-ɛ turbulence model was used to account for the effect of turbulence. The HVSFS process involves two combustion reactions. A primary combustion process is the premixed oxygen-propane reaction and secondary process is the non-premixed oxygen-gaseous ethanol reaction. For each reaction, one step global reaction, which takes dissociations and intermediate reactions into account, was derived from the equilibrium chemistry code developed by Gordon and McBride and eddy dissipation model was used to calculate the rate of reactions based on the transport equations for all species (10 species) mass fractions. Droplets were tracked in the continuum in a Lagrangian approach. In this paper, flow field inside and outside the gun simulated to provide clear and complete insight about the HVSFS processes. Moreover, the effect of some operative parameters (oxy-fuel flow rate, ethanol flow rate, droplets injection velocity and droplets size) on the gas flow field along the centerline and droplets evaporation behavior was discussed.

  11. Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of

  12. Powder bed binder jet 3D printing of Inconel 718: Densification, microstructural evolution and challenges

    DOE PAGES

    Nandwana, Peeyush; Elliott, Amy M.; Siddel, Derek; ...

    2017-01-03

    Traditional manufacturing of Inconel 718 components from castings and thermomechanical processing routes involve extensive post processing and machining to attain the desired geometry. Additive manufacturing (AM) technologies including direct energy deposition (DED), selective laser melting (SLM), electron beam melting (EBM) and binder jet 3D printing (BJ3DP) can minimize scrap generation and reduce lead times. While there is extensive literature on the use of melting and solidification based AM technologies, there has been limited research on the use of binder jet 3D printing. In this paper, a brief review on binder jet additive manufacturing of Inconel 718 is presented. In addition,more » existing knowledge on sintering of Inconel 718 has been extended to binder jet 3D printing. We found that supersolidus liquid phase sintering (SLPS) is necessary to achieve full densification of Inconel 718. SLPS is sensitive to the feedstock chemistry that has a strong influence on the liquid volume fraction at the processing temperature. Based on these results, we discuss an empirical framework to determine the role of powder particle size and liquid volume fraction on sintering kinetics. In conclusion, the role of powder packing factor and binder saturation on microstructural evolution is discussed. The current challenges in the use of BJ3DP for fabrication of Inconel 718, as well as, extension to other metal systems, are presented.« less

  13. Galvanic Corrosion Behavior of Microwave Welded and Post-weld Heat-Treated Inconel-718 Joints

    NASA Astrophysics Data System (ADS)

    Bansal, Amit; Sharma, Apurbba Kumar; Kumar, Pradeep

    2017-05-01

    In the present study, corrosion behavior of microwave welded Inconel-718 at various conditions was investigated. Welding of Inconel-718 in 980 °C solution-treated condition was performed using microwave hybrid heating technique. The microwave welds were subjected to post-heat treatment for improving its microstructure and mechanical properties by solubilizing the Nb-enriched Laves phase. The microstructural features of the fabricated welds at various conditions were investigated through scanning electron microscopy. The electrochemical testing results revealed that Inconel-718 welds were galvanic corroded when they were anodically polarized in 3.5 wt.% NaCl solution at 28 °C. The difference in the corrosion potentials between the base metal (BM) and fusion zone (FZ) in an Inconel-718 weld was the main factor for galvanic corrosion. The highest corrosion was occurred in the as-welded/aged weldments, followed by 980 °C solution-treated and aged weldments, as-welded specimen, and 1080 °C solution-treated and aged (1080STA) weldments. The least galvanic corrosion was occurred in the 1080STA specimens due to almost uniform microstructure developed in the weldment after the treatment. Thus, it was possible to minimize the galvanic corrosion in the microwave welded Inconel-718 by 1080STA treatment which resulted in reducing the difference in corrosion potentials between the BM and the FZ.

  14. Cold spray nozzle design

    DOEpatents

    Haynes, Jeffrey D.; Sanders, Stuart A.

    2009-06-09

    A nozzle for use in a cold spray technique is described. The nozzle has a passageway for spraying a powder material, the passageway having a converging section and a diverging section, and at least the diverging section being formed from polybenzimidazole. In one embodiment of the nozzle, the converging section is also formed from polybenzimidazole.

  15. Mechanical properties of nanostructured nickel based superalloy Inconel 718

    NASA Astrophysics Data System (ADS)

    Mukhtarov, Sh; Ermachenko, A.

    2010-07-01

    This paper will describe the investigations of a nanostructured (NS) state of nickel based INCONEL® alloy 718. This structure was generated in bulk semiproducts by severe plastic deformation (SPD) via multiple isothermal forging (MIF) of a coarse-grained alloy. The initial structure consisted of γ-phase grains with disperse precipitations of γ"-phase in the forms of discs, 50-75 nm in diameter and 20 nm in thickness. The MIF generated structures possess a large quantity of non-coherent plates and rounded precipitations of δ-phase, primarily along grain boundaries. In the duplex (γ+δ) structure the grains have high dislocation density and a large number of nonequilibrium boundaries. Investigations to determine mechanical properties of the alloy in a nanostructured state were carried out. Nanocrystalline Inconel 718 (80 nm) possesses a very high room-temperature strength after SPD. Microcrystalline (MC) and NS states of the alloy were subjected to strengthening thermal treatment, and the obtained results were compared in order to determine their mechanical properties at room and elevated temperatures.

  16. Temperature Measurement and Numerical Prediction in Machining Inconel 718

    PubMed Central

    Tapetado, Alberto; Vázquez, Carmen; Miguélez, Henar

    2017-01-01

    Thermal issues are critical when machining Ni-based superalloy components designed for high temperature applications. The low thermal conductivity and extreme strain hardening of this family of materials results in elevated temperatures around the cutting area. This elevated temperature could lead to machining-induced damage such as phase changes and residual stresses, resulting in reduced service life of the component. Measurement of temperature during machining is crucial in order to control the cutting process, avoiding workpiece damage. On the other hand, the development of predictive tools based on numerical models helps in the definition of machining processes and the obtainment of difficult to measure parameters such as the penetration of the heated layer. However, the validation of numerical models strongly depends on the accurate measurement of physical parameters such as temperature, ensuring the calibration of the model. This paper focuses on the measurement and prediction of temperature during the machining of Ni-based superalloys. The temperature sensor was based on a fiber-optic two-color pyrometer developed for localized temperature measurements in turning of Inconel 718. The sensor is capable of measuring temperature in the range of 250 to 1200 °C. Temperature evolution is recorded in a lathe at different feed rates and cutting speeds. Measurements were used to calibrate a simplified numerical model for prediction of temperature fields during turning. PMID:28665312

  17. Temperature Measurement and Numerical Prediction in Machining Inconel 718.

    PubMed

    Díaz-Álvarez, José; Tapetado, Alberto; Vázquez, Carmen; Miguélez, Henar

    2017-06-30

    Thermal issues are critical when machining Ni-based superalloy components designed for high temperature applications. The low thermal conductivity and extreme strain hardening of this family of materials results in elevated temperatures around the cutting area. This elevated temperature could lead to machining-induced damage such as phase changes and residual stresses, resulting in reduced service life of the component. Measurement of temperature during machining is crucial in order to control the cutting process, avoiding workpiece damage. On the other hand, the development of predictive tools based on numerical models helps in the definition of machining processes and the obtainment of difficult to measure parameters such as the penetration of the heated layer. However, the validation of numerical models strongly depends on the accurate measurement of physical parameters such as temperature, ensuring the calibration of the model. This paper focuses on the measurement and prediction of temperature during the machining of Ni-based superalloys. The temperature sensor was based on a fiber-optic two-color pyrometer developed for localized temperature measurements in turning of Inconel 718. The sensor is capable of measuring temperature in the range of 250 to 1200 °C. Temperature evolution is recorded in a lathe at different feed rates and cutting speeds. Measurements were used to calibrate a simplified numerical model for prediction of temperature fields during turning.

  18. Hydrostatic Stress Effect On the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2002-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has no effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of notched geometries. New experiments and nonlinear finite element analyses (FEA) of Inconel 100 (IN 100) equal-arm bend and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions was performed. In all test cases, the von Mises constitutive model, which is independent of hydrostatic pressure, overestimated the load for a given displacement or strain. Considering the failure displacements or strains, the Drucker-Prager FEMs predicted loads that were 3% to 5% lower than the von Mises values. For the failure loads, the Drucker Prager FEMs predicted strains that were 20% to 35% greater than the von Mises values. The Drucker-Prager yield function seems to more accurately predict the overall specimen response of geometries with significant internal hydrostatic stress influence.

  19. Weldability testing of Inconel{trademark} filler metals

    SciTech Connect

    Hood, B.B.; Lin, W.

    1995-12-31

    This paper presents the findings of a research program aimed at quantifying the weld solidification cracking susceptibility and weld metal liquation cracking susceptibility of Inconel{trademark} filler materials 52, 82, 152 and 182 deposited on a variety of materials intended for pressurized water reactor applications. A cursory investigation on the repair weldability of Filler Metal 52 using the Gleeble{trademark} thermo-mechanical simulation technique is also included. The brittle temperature range (BTR) in the fusion zone and HAZ was determined using the longitudinal-Varestraint test and spot-Varestraint test, respectively, and used as a weldability index for quantification of susceptibility to weld solidification cracking and HAZ liquation cracking. Results from this study showed that Filler Metals 52 exhibited the best resistance to both weld solidification cracking and weld metal liquation cracking followed by 82, 152 and 182 for the base metal combinations tested in this study. Repair weldability study suggested that the resistance to weld metal liquation cracking of 52 all weld metal would not be significantly reduced after ten times of weld simulation at peak temperatures of 900 C and 1,300 C.

  20. [INVITED] Laser treatment of Inconel 718 alloy and surface characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.; Al-Aqeeli, N.; Karatas, C.

    2016-04-01

    Laser surface texturing of Inconel 718 alloy is carried out under the high pressure nitrogen assisting gas. The combination of evaporation and melting at the irradiated surface is achieved by controlling the laser scanning speed and the laser output power. Morphological and metallurgical changes in the treated surface are analyzed using the analytical tools including optical, electron scanning, and atomic force microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardnes and friction coefficient of the laser treated surface are measured. Residual stress formed in the surface region is determined from the X-ray diffraction data. Surface hydrophobicity of the laser treated layer is assessed incorporating the sessile drop method. It is found that laser treated surface is free from large size asperities including cracks and the voids. Surface microhardness increases significantly after the laser treatment process, which is attributed to the dense layer formation at the surface under the high cooling rates, dissolution of Laves phase in the surface region, and formation of nitride species at the surface. Residual stress formed is compressive in the laser treated surface and friction coefficient reduces at the surface after the laser treatment process. The combination of evaporation and melting at the irradiated surface results in surface texture composes of micro/nano-poles and pillars, which enhance the surface hydrophobicity.

  1. Hydrostatic Stress Effect on the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2003-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has negligible effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of various geometries. Fatigue tests and nonlinear finite element analyses (FEA) of Inconel 100 (IN100) equal-arm bend specimens and new monotonic tests and nonlinear finite element analyses of IN100 smooth tension, smooth compression, and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions were performed. A new FEA constitutive model was developed that incorporates a pressure-dependent yield function with combined multilinear kinematic and multilinear isotropic hardening using the ABAQUS user subroutine (UMAT) utility. In all monotonic tensile test cases, the von Mises constitutive model, overestimated the load for a given displacement or strain. Considering the failure displacements or strains for the DENT specimen, the Drucker-Prager FEM s predicted loads that were approximately 3% lower than the von Mises values. For the failure loads, the Drucker Prager FEM s predicted strains that were up to 35% greater than the von Mises values. Both the Drucker-Prager model and the von Mises model performed equally-well in simulating the equal-arm bend fatigue test.

  2. Investigation of failure to separate an Inconel 718 frangible nut

    NASA Technical Reports Server (NTRS)

    Hoffman, William C., III; Hohmann, Carl

    1994-01-01

    The 2.5-inch frangible nut is used in two places to attach the Space Shuttle Orbiter to the External Tank. It must be capable of sustaining structural loads and must also separate into two pieces upon command. Structural load capability is verified by proof loading each flight nut, while ability to separate is verified on a sample of a production lot. Production lots of frangible nuts beginning in 1987 experienced an inability to reliably separate using one of two redundant explosive boosters. The problems were identified in lot acceptance tests, and the cause of failure has been attributed to differences in the response of the Inconel 718. Subsequent tests performed on the frangible nuts resulted in design modifications to the nuts along with redesign of the explosive booster to reliably separate the frangible nut. The problem history along with the design modifications to both the explosive booster and frangible nut are discussed in this paper. Implications of this failure experience impact any pyrotechnic separation system involving fracture of materials with respect to design margin control and lot acceptance testing.

  3. Ultrasonic guided wave inspection of Inconel 625 brazed lap joints

    NASA Astrophysics Data System (ADS)

    Comot, Pierre; Bocher, Philippe; Belanger, Pierre

    2016-04-01

    The aerospace industry has been investigating the use of brazing for structural joints, as a mean of reducing cost and weight. There therefore is a need for a rapid, robust, and cost-effective non-destructive testing method for evaluating the structural integrity of the joints. The mechanical strength of brazed joints depends mainly on the amount of brittle phases in their microstructure. Ultrasonic guided waves offer the possibility of detecting brittle phases in joints using spatio-temporal measurements. Moreover, they offer the opportunity to inspect complex shape joints. This study focused on the development of a technique based on ultrasonic guided waves for the inspection of Inconel 625 lap joints brazed with BNi-2 filler metal. A finite element model of a lap joint was used to optimize the inspection parameters and assess the feasibility of detecting the amount of brittle phases in the joint. A finite element parametric study simulating the input signal shape, the center frequency, and the excitation direction was performed. The simulations showed that the ultrasonic guided wave energy transmitted through, and reflected from, the joints was proportional to the amount of brittle phases in the joint.

  4. Experimental Investigations during Dry EDM of Inconel - 718

    NASA Astrophysics Data System (ADS)

    BHANDARE, A. S.; DABADE, U. A.

    2016-02-01

    Dry EDM is a modification of the conventional EDM process in which the liquid dielectric is replaced by a gaseous medium. Tubular tool electrodes are used and as the tool rotates, high velocity gas is supplied through it into the discharge gap. The flow of high velocity gas into the gap facilitates removal of debris and prevents excessive heating of the tool and work piece at the discharge spots. It is now known that apart from being an environment- friendly process, other advantages of the dry EDM process are low tool wear, lower discharge gap, lower residual stresses, smaller white layer and smaller heat affected zone. Keeping literature review into consideration, in this paper, an attempt has been made by selecting compressed air as a dielectric medium, with Inconel - 718 as a work piece material and copper as a tool electrode. Experiments are performed using Taguchi DoE orthogonal array to observe and analyze the effects of different process parameters to optimize the response variables such as material removal rate (MRR), surface roughness (Ra) and tool wear rate (TWR). In the current work, a unit has been developed to implement dry EDM process on existing oil based EDM machine.

  5. Oxidation of Inconel alloy MA754 at low oxidation potential

    SciTech Connect

    Braski, D.N.; Goodell, P.D.; Cathcart, J.V.; Kane, R.H.

    1983-01-01

    It has been known for some time that the addition of small oxide particles to an 80 Ni-20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance was studied. Initial experiments were performed using inconel alloy MA754, which is nominally: 78 Ni, 20 Cr, 0.05 C, 0.3 Al, 0.5 Ti, 1.0 Fe, and 0.6 Y/sub 2/O/sub 3/ (wt %). Small disks (3 mm diam x 0.38 mm thick) were cut from MA754 plate stock and prepared with two different surface conditions. The first was prepared by mechanically polishing one side of a disk through 0.5 ..mu..m diamond on a syntron polisher while the second used an additional sulfuric acid-methanol electropolishing treatment to remove the cold-worked surface layer. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000/sup 0/C. Three different environments were investigated: hydrogen with nominal dew points of 0/sup 0/C, -25/sup 0/C, and -55/sup 0/C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by backpolishing to the oxide/metal interface. The particles were analyzed by EDS and SAD. Preliminary results are given.

  6. Friction Freeform Fabrication of Superalloy Inconel 718: Prospects and Problems

    NASA Astrophysics Data System (ADS)

    Dilip, J. J. S.; Janaki Ram, G. D.

    2013-12-01

    Friction Freeform Fabrication is a new solid-state additive manufacturing process. The present investigation reports a detailed study on the prospects of this process for additive part fabrication in superalloy Inconel 718. Using a rotary friction welding machine and employing alloy 718 consumable rods in solution treated condition, cylindrical-shaped multi-layer friction deposits (10 mm diameter) were successfully produced. In the as-deposited condition, the deposits showed very fine grain size with no grain boundary δ phase. The deposits responded well to direct aging and showed satisfactory room-temperature tensile properties. However, their stress rupture performance was unsatisfactory because of their layered microstructure with very fine grain size and no grain boundary δ phase. The problem was overcome by heat treating the deposits first at 1353 K (1080 °C) (for increasing the grain size) and then at 1223 K (950 °C) (for precipitating the δ phase). Overall, the current study shows that Friction Freeform Fabrication is a very useful process for additive part fabrication in alloy 718.

  7. Hydrostatic Stress Effect on the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2003-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has negligible effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of various geometries. Fatigue tests and nonlinear finite element analyses (FEA) of Inconel 100 (IN100) equal-arm bend specimens and new monotonic tests and nonlinear finite element analyses of IN100 smooth tension, smooth compression, and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions were performed. A new FEA constitutive model was developed that incorporates a pressure-dependent yield function with combined multilinear kinematic and multilinear isotropic hardening using the ABAQUS user subroutine (UMAT) utility. In all monotonic tensile test cases, the von Mises constitutive model, overestimated the load for a given displacement or strain. Considering the failure displacements or strains for the DENT specimen, the Drucker-Prager FEM s predicted loads that were approximately 3% lower than the von Mises values. For the failure loads, the Drucker Prager FEM s predicted strains that were up to 35% greater than the von Mises values. Both the Drucker-Prager model and the von Mises model performed equally-well in simulating the equal-arm bend fatigue test.

  8. Environmentally compatible spray cement

    SciTech Connect

    Loeschnig, P.

    1995-12-31

    Within the framework of a European research project, Heidelberger Zement developed a quickly setting and hardening binder for shotcrete, called Chronolith S, which avoids the application of setting accelerators. Density and strength of the shotcrete produced with this spray cement correspond to those of an unaccelerated shotcrete. An increased hazard for the heading team and for the environment, which may occur when applying setting accelerators, can be excluded here. Owing to the special setting properties of a spray cement, the process engineering for its manufacturing is of great importance. The treatment of a spray cement as a dry concrete with kiln-dried aggregates is possible without any problems. The use of a naturally damp pre-batched mixture is possible with Chronolith S but requires special process engineering; spray cement and damp aggregate are mixed with one another immediately before entering the spraying machinery.

  9. Spray measurement technology: a review

    NASA Astrophysics Data System (ADS)

    Fansler, Todd D.; Parrish, Scott E.

    2015-01-01

    Sprays are among the most intellectually challenging and practically important topics in fluid mechanics. This paper reviews needs, milestones, challenges, and a broad array of techniques for spray measurement. In addition, tabular summaries provide cross-referenced entry points to the vast literature by organizing over 300 citations according to key spray phenomena, physical parameters and measurement techniques for each of the principal spray regions (nozzle internal flow, near-field spray-formation region, far-field developed spray, and spray-wall interaction). The article closes with perspectives on some current issues in spray research, including the cost and complexity of apparatus for spray physics and spray engineering, the need for simultaneous diagnostic measurements under application-relevant conditions, and the effective comparison of spray measurements and numerical simulations.

  10. Spray Rolling Aluminum Strip

    SciTech Connect

    Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.

    2006-05-10

    Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.

  11. An overview of spray drift reduction testing of spray nozzles

    USDA-ARS?s Scientific Manuscript database

    The importance of the development and testing of drift reduction technologies (DRTs) is increasing. Common spray drift reduction technologies include spray nozzles and spray adjuvants. Following draft procedures developed for a DRT program, three spray nozzles were tested under high air speed cond...

  12. Response of Inconel 617 superalloy to combined ground-based and STS reentry exposure

    NASA Technical Reports Server (NTRS)

    Clark, R. K.; Unnam, J.

    1984-01-01

    Inconel 617 is a nickel-based superalloy which is being considered for heat-shield applications because of its high-temperature strength, good oxidation resistance and high emittance of oxidized surfaces. While the effects of simulated reentry conditions on emittance and oxidation of Inconel 617 have been studied, the combined effects of the ground-based environment with sea salt exposure and the reentry environment have not been evaluated. Experimental results are presented to show the effects of environmental simulation including ground-based and reentry exposure on the emittance and oxidation of Inconel 617. Specimens were exposed to simulated reentry at a surface temperature of 2000 F in the Langley Research Center Hypersonic Materials Environmental Test System (HYMETS) Facility with and without alternate exposures to an atmospheric seashore environment or a laboratory sea salt environment. This paper presents emittance, mass loss, oxide chemistry, and alloy composition data for the specimens.

  13. Effects on stress rupture life and tensile strength of tin additions to Inconel 718

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Johnson, W.

    1982-01-01

    Because Inconel 718 represents a major use of columbium and a large potential source of columbium for aerospace alloys could be that of columbium derived from tin slags, the effects of tin additions to Inconel 718 at levels which might be typical of or exceed those anticipated if tin slag derived columbium were used as a melting stock were investigated. Tin was added to 15 pound Inconel 718 heats at levels varying from none added to approximately 10,000 ppm (1 wt%). Limited 1200 F stress rupture testing was performed at stresses from 68,000 to 115,000 psi and a few tensile tests were performed at room temperature, 800 and 1200 F. Additions of tin in excess of 800 ppm were detrimental to ductility and stress rupture life.

  14. Effects on stress rupture life and tensile strength of tin additions to Inconel 718

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Johnson, W.

    1982-01-01

    Because Inconel 718 represents a major use of columbium and a large potential source of columbium for aerospace alloys could be that of columbium derived from tin slags, the effects of tin additions to Inconel 718 at levels which might be typical of or exceed those anticipated if tin slag derived columbium were used as a melting stock were investigated. Tin was added to 15 pound Inconel 718 heats at levels varying from none added to approximately 10,000 ppm (1 wt%). Limited 1200 F stress rupture testing was performed at stresses from 68,000 to 115,000 psi and a few tensile tests were performed at room temperature, 800 and 1200 F. Additions of tin in excess of 800 ppm were detrimental to ductility and stress rupture life.

  15. A joint computational and experimental study to evaluate Inconel-sheathed thermocouple performance in flames.

    SciTech Connect

    Brundage, Aaron L.; Nicolette, Vernon F.; Donaldson, A. Burl; Kearney, Sean Patrick; Gill, Walter

    2005-09-01

    A joint experimental and computational study was performed to evaluate the capability of the Sandia Fire Code VULCAN to predict thermocouple response temperature. Thermocouple temperatures recorded by an Inconel-sheathed thermocouple inserted into a near-adiabatic flat flame were predicted by companion VULCAN simulations. The predicted thermocouple temperatures were within 6% of the measured values, with the error primarily attributable to uncertainty in Inconel 600 emissivity and axial conduction losses along the length of the thermocouple assembly. Hence, it is recommended that future thermocouple models (for Inconel-sheathed designs) include a correction for axial conduction. Given the remarkable agreement between experiment and simulation, it is recommended that the analysis be repeated for thermocouples in flames with pollutants such as soot.

  16. Effects of Cations on Corrosion of Inconel 625 in Molten Chloride Salts

    NASA Astrophysics Data System (ADS)

    Zhu, Ming; Ma, Hongfang; Wang, Mingjing; Wang, Zhihua; Sharif, Adel

    2016-04-01

    Hot corrosion of Inconel 625 in sodium chloride, potassium chloride, magnesium chloride, calcium chloride and their mixtures with different compositions is conducted at 900°C to investigate the effects of cations in chloride salts on corrosion behavior of the alloy. XRD, SEM/EDS were used to analyze the compositions, phases, and morphologies of the corrosion products. The results showed that Inconel 625 suffers more severe corrosion in alkaline earth metal chloride molten salts than alkaline metal chloride molten salts. For corrosion in mixture salts, the corrosion rate increased with increasing alkaline earth metal chloride salt content in the mixture. Cations in the chloride molten salts mainly affect the thermal and chemical properties of the salts such as vapor pressure and hydroscopicities, which can affect the basicity of the molten salt. Corrosion of Inconel 625 in alkaline earth metal chloride salts is accelerated with increasing basicity.

  17. Effects of tin on microstructure and mechanical behavior of Inconel 718

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Johnson, W. A.; Maurer, G. A.

    1984-01-01

    Columbium, for which the United States is 100 percent import reliant, is of strategic importance to the U.S. aerospace industry. A major amount of the Cb is used in Inconel 718. Should Cb sources be disrupted, it may be desired to use a grade of Cb melting stock having greater Sn content then the preferred vacuum rade. Additions of Sn to Inconel 718 were varied from none added to 1 wt %. The Sn additions below 800 ppm had no detrimental effects on 650 C stress rupture behavior; however, 1-wt % Sn severely degraded both life and ductility. Additions of Sn in excess of 200 ppm were slightly detrimental to the 425 C tensile yield strength and ductility. The Sn additions had no effect on the microstructure of Inconel 718 even after stress rupture testing for over 6000 hr at 650 C.

  18. Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

    NASA Astrophysics Data System (ADS)

    Rodriguez, David; Merwin, Augustus; Karmiol, Zachary; Chidambaram, Dev

    2017-05-01

    Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325 °C and supercritical water at 425 °C and 527.5 °C for 2 h was studied. After exposure to 325 °C subcritical water, the CrO42- based film formed; however minor quantities of NiFexCr2-xO4 spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425 °C consisted of NiFexCr2-xO4 spinel. The surface films on both alloys were identified as NiFe2O4 when exposed to supercritical water at 527.5 °C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600 °C. Samples were exposed to these temperatures for 24, 96, and 200 h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

  19. Thermal Arc Spray Overview

    NASA Astrophysics Data System (ADS)

    Hafiz Abd Malek, Muhamad; Hayati Saad, Nor; Kiyai Abas, Sunhaji; Mohd Shah, Noriyati

    2013-06-01

    Usage of protective coating for corrosion protection was on highly demand during the past decade; and thermal spray coating played a major part during that time. In recent years, the thermal arc spray coating becomes a popular coating. Many big players in oil and gas such as PETRONAS, EXXON MOBIL and SHELL in Malaysia tend to use the coating on steel structure as a corrosion protection. Further developments in coating processes, the devices, and raw materials have led to expansion of functional coatings and applications scope from conventional coating to specialized industries. It is widely used because of its ability to withstand high process temperature, offer advantages in efficiency, lower cost and acts as a corrosion protection. Previous research also indicated that the thermal arc spray offers better coating properties compared to other methods of spray. This paper reviews some critical area of thermal spray coating by discussing the process/parameter of thermal arc spray technology and quality control of coating. Coating performance against corrosion, wear and special characteristic of coating are also described. The field application of arc spray technology are demonstrated and reviewed.

  20. Modeling of precipitation strengthening in Inconel 718 including non-spherical γ″ precipitates

    NASA Astrophysics Data System (ADS)

    Ahmadi, M. R.; Rath, M.; Povoden-Karadeniz, E.; Primig, S.; Wojcik, T.; Danninger, A.; Stockinger, M.; Kozeschnik, E.

    2017-07-01

    In this study, the classical strengthening equations for weak and strong particles are advanced to account for oblate-shaped γ″ precipitates in Inconel 718. The model is verified on quantitative stereology of size and distribution for both shearable and non-shearable mechanisms. The evolution of precipitation strengthening of aged superalloy Inconel 718 is simulated. In addition to precipitation strengthening, contributions of solid solution strengthening and the grain size effect are considered. Simulation results indicate a sound prediction of the final yield strength based on the presented model.

  1. Microstructural and tensile characterization of Inconel 718 laser coatings for aeronautic components

    NASA Astrophysics Data System (ADS)

    Lambarri, Jon; Leunda, Josu; García Navas, Virginia; Soriano, Carlos; Sanz, Carmen

    2013-07-01

    The suitability of the laser cladding technique for manufacturing and repairing aeronautic components of Inconel 718 was evaluated. Multilayer coatings were deposited on Inconel 718 plates, using a continuous wave Nd:YAG laser. The microstructure of the laser cladding samples was investigated using optical and scanning electron microscopy and microhardness profiles were measured after different heat treatment stages. Finally, tensile tests were carried out on fully aged samples extracted from a massive multilayer coating. It was proven that the resulting coatings satisfy the industrial requirements for aeronautic applications, with mechanical properties well above the minimum specified values and with no detrimental phases or precipitates left after the heat treatment.

  2. Qualification Data for the Corrosion Behavior of Inconel and Steel Alloys in Nitric Acid

    SciTech Connect

    Mickalonis, J.I.

    2001-04-17

    During filling operations in the Defense Waste Processing Facility (DWPF), melter inserts made of Inconel 690 (I690) have fallen into the canisters which are made of 304L stainless steel (304L). The consequences of possible galvanic corrosion between these materials were evaluated using two electrochemical techniques. Materials for other items which might fall into the canisters were also evaluated including Inconel MA758 (MA758) and A537 carbon steel (A537). The test solutions were concentrated nitric acid, used for validating literature data, and a 10 M nitric acid solution for simulating a possible environment, which may develop due to radiolysis inside the sealed canister.

  3. Qualification Data for the Corrosion Behavior of Inconel and Steel Alloys in Nitric Acid

    SciTech Connect

    Mickalonis, J.I.

    2001-05-02

    During filling operations in the Defense Waste Processing Facility (DWPF), melter inserts made of Inconel 690 (I690) have fallen into the canisters which are made of 304L stainless steel (304L). The consequences of possible galvanic corrosion between these materials were evaluated using two electrochemical techniques. Materials for other items which might fall into the canisters were also evaluated including Inconel MA758 (MA758) and A537 carbon steel (A537). The test solutions were concentrated nitric acid, used for validating literature data, and a 10 M nitric acid solution for simulating a possible environment, which may develop due to radiolysis inside the sealed canister.

  4. Proton irradiation creep of Inconel 718 at 300°C

    NASA Astrophysics Data System (ADS)

    Scholz, R.; Matera, R.

    2000-12-01

    Torsional creep tests were conducted on Inconel 718 in the precipitation hardened condition under 17 MeV proton irradiation at 300°C upto a maximum dose of 0.35 dpa. The stress dependence of the irradiation creep rate was linear for the applied shear stresses which ranged from 150 to 450 MPa. The results are discussed in relation to the operating conditions of an ITER-like machine, where Inconel 718 bolts are used to mechanically attach the shielding blanket to the backplate. The irradiation creep induced stress relaxation amounted to about 30% after a dose of 0.35 dpa.

  5. Fracture evaluation of thermally sprayed coatings in dependence on cohesive strength

    NASA Astrophysics Data System (ADS)

    Schubert, J.; Česánek, Z.

    2017-05-01

    Measuring the cohesive strength of thermally sprayed coatings is relatively difficult matter, which can be accessed in many directions. This issue is nowadays solved by use of Scratch test method. This method is not completely sufficient for the cohesive strength testing because the coating is under load of combined stresses during the Scratch test. The reason to develop this method was need for exact measurement of tensile cohesion toughness of thermally sprayed coatings, which could provide results as close to a classic tensile test as possible. Another reason for development of this method was the impossibility of direct comparison with results obtained by other methods. Tested coatings were prepared using HP / HVOF (Stellite 6, NiCrBSi, CrC-NiCr and Hastelloy C-276). These coatings were selected as commonly used in commercial sector and also on because of rising customer demand for ability to provide such coating characteristics. The tested coatings were evaluated in terms of cohesive strength (method based on tensile strength test). Final fractures were evaluated by optical microscopy together with scanning electron microscopy and EDS analysis. As expected higher cohesive strength showed metallic coatings with top results of coating Stellite 6. Carbide coatings showed approximately third of the cohesion strength in comparison with metal based coating.

  6. Investigation of thermal spray coatings on austenitic stainless steel substrate to enhance corrosion protection

    NASA Astrophysics Data System (ADS)

    Rogers, Daniel M.

    The research is aimed to evaluate thermal spray coatings to address material issues in supercritical and ultra-supercritical Rankine cycles. The primary purpose of the research is to test, evaluate, and eventually implement a coating to improve corrosion resistance and increase efficiency of coal fired power plants. The research is performed as part of a comprehensive project to evaluate the ability of titanium, titanium carbide, or titanium diboride powders to provide fireside corrosion resistance in supercritical and ultra-supercritical steam boilers, specifically, coal driven boilers in Illinois that must utilize high sulfur and high chlorine content coal. [1] The powder coatings that were tested are nano-sized titanium carbide (TiC) and titanium di-boride (TiB2) powders that were synthesized by a patented process at Southern Illinois University. The powders were then sent to Gas Technology Institute in Chicago to coat steel coupons by HVOF (High Velocity Oxy-Fuel) thermal spray technique. The powders were coated on an austenitic 304H stainless steel substrate which is commonly found in high temperature boilers, pipelines, and heat exchangers. The samples then went through various tests for various lengths of time under subcritical, supercritical, and ultra-supercritical conditions. The samples were examined using a scanning electron microscope and x-ray diffraction techniques to study microstructural changes and then determined which coating performed best.

  7. Fabrication and Optimization of Ni Superalloy Inconel 600 Microtruss Materials

    NASA Astrophysics Data System (ADS)

    Devatha Venkatesh, Balaji

    Microtruss materials are multifunctional cellular hybrids composed of an interconnected arrangement of internal struts that can offer enhanced strength and stiffness at low densities. This study looks at the potential of Ni-based superalloys as microtruss materials. The potential of using the in-situ plastic strain imparted during stretch forming to grain boundary engineer the internal struts of Inconel 600 (IN600) cellular hybrids was also explored. In order to examine this question, a combination of experimental and finite element (FE) methods were employed. The non-uniform plastic deformation imparted to the microtruss struts during fabrication was modeled by FE and the local changes in grain boundary character in the fabricated trusses were mapped by electron backscattered diffraction. This study also examined the distribution of plastic strain over the microtruss architecture. A mechanical press with various pin geometries was employed to experimentally validate the FE models. Standard pin geometry results in substantially non-uniform plastic strain, which limits the maximum formability of the starting sheet material. Importantly, pins designed with tapers and spheres were shown to impart plastic strain along the entire length of the microtruss. This opened up possibility of new design strategies for facilitating grain boundary engineering over the entire truss. It may also present opportunities for enhancing the energy absorption performance of microtruss materials. Finally, this study examined the mechanical properties of IN600 microtrusses, in particular focusing on the significance of strut end constraints in determining the overall mechanical performance. While it is straightforward to analytically determine the inelastic buckling resistance of plastically deformed struts, there is no simple way to determine the rotational end constraint of the struts deformed to varying truss angles. It was seen that end constraint rigidity k could be determined using a

  8. Wear resistance of WC/Co HVOF-coatings and galvanic Cr coatings modified by diamond nanoparticles

    NASA Astrophysics Data System (ADS)

    Kandeva, M.; Grozdanova, T.; Karastoyanov, D.; Assenova, E.

    2017-02-01

    The efforts in the recent 20 years are related to search of ecological solutions in the tribotechnologies for the replacement of galvanic Cr coatings in the contact systems operating under extreme conditions: abrasion, erosion, cavitation, corrosion, shock and vibration loads. One of the solutions is in the composite coatings deposited by high velocity gas-flame process (HVOF). The present paper presents comparative study results for mechanical and tribological characteristics of galvanic Cr coatings without nanoparticles, galvanic Cr coatings modified by diamond nanoparticles NDDS of various concentration 0.6; 10; 15 и 20% obtained under three technological regimes, and composite WC-12Co coating. Comparative results about hardness, wear, wear resistance and friction coefficient are obtained for galvanic Cr-NDDS and WC-12Co coatings operating at equal friction conditions of dry friction on abrasive surface. The WC-12Co coating shows 5.4 to 7 times higher wear resistance compared to the galvanic Cr-NDDS coatings.

  9. Electrochemical Study of Ni20Cr Coatings Applied by HVOF Process in ZnCl2-KCl at High Temperatures

    PubMed Central

    Porcayo-Calderón, J.; Sotelo-Mazón, O.; Casales-Diaz, M.; Ascencio-Gutierrez, J. A.; Salinas-Bravo, V. M.; Martinez-Gomez, L.

    2014-01-01

    Corrosion behavior of Ni20Cr coatings deposited by HVOF (high velocity oxygen-fuel) process was evaluated in ZnCl2-KCl (1 : 1 mole ratio) molten salts. Electrochemical techniques employed were potentiodynamic polarization curves, open circuit potential, and linear polarization resistance (LPR) measurements. Experimental conditions included static air and temperatures of 350, 400, and 450°C. 304-type SS was evaluated in the same conditions as the Ni20Cr coatings and it was used as a reference material to assess the coatings corrosion resistance. Coatings were evaluated as-deposited and with a grinded surface finished condition. Results showed that Ni20Cr coatings have a better corrosion performance than 304-type SS. Analysis showed that Ni content of the coatings improved its corrosion resistance, and the low corrosion resistance of 304 stainless steel was attributed to the low stability of Fe and Cr and their oxides in the corrosive media used. PMID:25210645

  10. Nasal corticosteroid sprays

    MedlinePlus

    ... best for decreasing symptoms during that season. Several brands of nasal corticosteroid sprays are available. They all ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows ...

  11. Budesonide Nasal Spray

    MedlinePlus

    ... by an allergy to pollen, mold, dust, or pets). Budesonide nasal spray should not be used to ... disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, ...

  12. Fluticasone Nasal Spray

    MedlinePlus

    ... the pump until you see a fine spray. Blow your nose until your nostrils are clear. Hold ... chills, cough, and other signs of infection whistling sound from the nose hives rash itching swelling of ...

  13. Supersonic-Spray Cleaner

    NASA Technical Reports Server (NTRS)

    Caimi, Raoul E. B.; Lin, Feng-Nan; Thaxton, Eric A.

    1995-01-01

    Spraying system for cleaning mechanical components uses less liquid and operates at pressures significantly lower. Liquid currently used is water. Designed to replace chlorofluorocarbon (CFC) solvent-based cleaning and cleanliness verification methods. Consists of spray head containing supersonic converging/diverging nozzles, source of gas at regulated pressure, pressurized liquid tank, and various hoses, fittings, valves, and gauges. Parameters of nozzles set so any of large variety of liquids and gases combined in desired ratio and rate of flow. Size and number of nozzles varied so system built in configurations ranging from small hand-held spray heads to large multinozzle cleaners. Also used to verify part adequately cleaned. Runoff liquid from spray directed at part collected. Liquid analyzed for presence of contaminants, and part recleaned if necessary.

  14. Beclomethasone Nasal Spray

    MedlinePlus

    ... the lining of the nose) after nasal polyp removal surgery. Beclomethasone nasal spray should not be used ... room temperature and away from excess heat and moisture (not in the bathroom).Unneeded medications should be ...

  15. Ciclesonide Nasal Spray

    MedlinePlus

    ... runny or itchy nose. Ciclesonide is in a class of medications called corticosteroids. It works by preventing ... hold the bottle firmly with your forefinger and middle finger on either side of the spray tip ...

  16. Flunisolide Nasal Spray

    MedlinePlus

    ... by the common cold. It is in a class of medications called corticosteroids. It works by blocking ... spray with the applicator between your forefinger and middle finger and the bottom of the bottle resting ...

  17. Nicotine Nasal Spray

    MedlinePlus

    ... the bottle in front of a tissue or paper towel. Pump the spray bottle six to eight times ... up the spill immediately with a cloth or paper towel. Avoid touching the liquid. Throw away the used ...

  18. Spray applicator for spraying coatings and other fluids in space

    NASA Technical Reports Server (NTRS)

    Kuminecz, J. F.; Lausten, M. F. (Inventor)

    1985-01-01

    A self contained spray application is developed for one handed operation in a zero gravity vacuum environment by a free flying astronaut not attached to any spacecraft. This spray applicator eliminates contamination of the operator by back spray. This applicator includes a rigid accumulator containment of a fluid within a flexible bladder the fluid being urged out of the accumulator under pressure through a spray gun. The spray gun includes a spring loaded lockable trigger which controls a valve. When in an open position, the fluid passes through the valve into the ambient environment in the form of a spray. A spray shield is provided which directs the flow of the spray from the applicator by trapping errant particles of spray yet allowing the passage of escaping gases through its material.

  19. Directed spray mast

    DOEpatents

    Nance, Thomas A.; Siddall, Alvin A.; Cheng, William Y.; Counts, Kevin T.

    2005-05-10

    Disclosed is an elongated, tubular, compact high pressure sprayer apparatus for insertion into an access port of vessels having contaminated interior areas that require cleaning by high pressure water spray. The invention includes a spray nozzle and a camera adjacent thereto with means for rotating and raising and lowering the nozzle so that areas identified through the camera may be cleaned with a minimum production of waste water to be removed.

  20. Metal atomization spray nozzle

    DOEpatents

    Huxford, Theodore J.

    1993-01-01

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal.

  1. Portable Spray Booth

    NASA Technical Reports Server (NTRS)

    Hansen, Timothy D.; Bardwell, Micheal J.

    1996-01-01

    Portable spray booth provides for controlled application of coating materials with high solvent contents. Includes contoured shroud and carbon filter bed limiting concentration of fumes in vicinity. Designed to substitute spraying for brush application of solvent-based adhesive prior to installing rubber waterproof seals over joints between segments of solid-fuel rocket motor. With minor adjustments and modifications, used to apply other solvent-based adhesives, paints, and like.

  2. Portable Spray Booth

    NASA Technical Reports Server (NTRS)

    Hansen, Timothy D.; Bardwell, Micheal J.

    1996-01-01

    Portable spray booth provides for controlled application of coating materials with high solvent contents. Includes contoured shroud and carbon filter bed limiting concentration of fumes in vicinity. Designed to substitute spraying for brush application of solvent-based adhesive prior to installing rubber waterproof seals over joints between segments of solid-fuel rocket motor. With minor adjustments and modifications, used to apply other solvent-based adhesives, paints, and like.

  3. Metal atomization spray nozzle

    DOEpatents

    Huxford, T.J.

    1993-11-16

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal. 6 figures.

  4. Plasma-sprayed coatings

    SciTech Connect

    Herman, H.

    1988-09-01

    Plasma spraying is one way to apply protective coatings. The hot, high-speed flame of a plasma gun can melt a powder of almost any ceramic or metal and spray it to form a coating for protection against corrosion, wear or high temperature. The technique carries much less risk of degrading the coating and substrate than many other high-temperature processes do, because the gas in the plasma flame is chemically inert and the target can be kept fairly cool. And yet a plasma gun can be only a little more cumbersome than a paint sprayer. Investigators are applying this technique to new materials. The General Electric Company is using vacuum plasma spraying to make freestanding components: intricate aircraft engine parts formed by plasma-spraying a superalloy on a removable substrate. Other workers spray ceramic particles or fibers and metal powder simulatious wrong, stiff composite materials: the ceramic particles dispersed in a matrix of metal. The author and colleagues at the U.S. Naval Research Laboratory have fabricated a thick film of high-temperature superconductor by plasma-spraying the compound in the form of a powder. 7 figs.

  5. Development of self-lubricating coatings via cold spray process: Feedstock formulation and deformation modeling

    NASA Astrophysics Data System (ADS)

    Aggarwal, Gaurav

    Because of their low density, high specific strength and high stiffness, titanium alloys are one of the prime candidates for structural application often requiring specific tribological properties. However, their relatively high friction coefficients and low wear resistance are limiting their application over a wider temperature range. Various coatings deposited with technologies like high velocity oxy flame (HVOF), detonation gun (DGun), electron beam physical vapor deposition (EB-PVD), etc., can improve wear performance and decrease corrosion damage. These technologies require high processing temperatures precluding the integration of thermally vulnerable lubricants. This research looks at a relatively new coating process called Cold Spray for self-lubricating coatings on Ti-6Al-4V alloys. Cold Spray can produce coatings without significant heating of the sprayed powder or substrate. The particles are in solid state as they hit the substrate, and the formation of coatings occurs mainly due to the kinetic energy of the particles. Therefore, the impact velocity plays an important role. Below a critical value, the particles can cause densification and abrasion of the substrate. The focus of this study is to design composite coatings for the cold spray process and determination of the critical velocity through finite element modeling. Different powders and feedstock formulation techniques are discussed in order to find an optimum formulation for self-lubricating coatings. A composite powder (Ni coated hBN) was found to be the best candidate for the feedstock. The deformation of composite particles upon impact on the substrate was modeled and compared to the experiments. A number of approaches involving different modeling platforms, particle-substrate geometries, and material models have been tried. This work presents the results of ANSYS (version 10.0) analysis using an axisymmetric model of the particle impact. Stress and strain distributions in the particle

  6. Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

    NASA Astrophysics Data System (ADS)

    Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

    2014-10-01

    20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

  7. Microstructure, Fatigue Behavior, and Failure Mechanisms of Direct Laser-Deposited Inconel 718

    NASA Astrophysics Data System (ADS)

    Johnson, Alex S.; Shao, Shuai; Shamsaei, Nima; Thompson, Scott M.; Bian, Linkan

    2016-12-01

    Inconel 718 is considered to be a superalloy with a series of superior properties such as high strength, creep resistance, and corrosion resistance at room and elevated temperatures. Additive manufacturing (AM) is particularly appealing to Inconel 718 because of its near-net-shape production capability for circumventing the poor machinability of this superalloy. Nevertheless, AM parts are prone to porosity, which is detrimental to their fatigue resistance. Thus, further understanding of their fatigue behavior is required before their widespread use in load-bearing applications. In this work, the microstructure and fatigue properties of AM Inconel 718, produced in a Laser Engineered Net Shaping (LENS™) system and heat treated with a standard heat treatment schedule, are evaluated at room temperature. Fully reversed strain controlled fatigue tests were performed on cylindrical specimens with straight gage sections at strain amplitudes ranging from 0.001 mm/mm to 0.01 mm/mm. The fracture surfaces of fatigue specimens were inspected with a scanning electron microscope. The results indicate that the employed heat treatment allowed the large, elongated grains and dendritic structure of the as-built material to break down into smaller, equiaxed grains, with some dendritic structures remaining between layers. The AM specimens were found to possess lower fatigue resistance than wrought Inconel 718, and this is primarily attributed to the presence of brittle metal-carbide/oxide inclusions or pores near their surface.

  8. Hot-cracking studies of Inconel 718 weld- heat-affected zones

    NASA Technical Reports Server (NTRS)

    Thompson, E. G.

    1969-01-01

    Hot ductility tests, gas-tungsten-arc fillerless fusion tests, and circle patch-weld-restraint tests were conducted on Inconel 718 to better understand and correlate the weldability /resistance to hot cracking/ of the alloy. A correlation of the test results with composition, heat-treat condition, grain size, and microstructure was made.

  9. Stress-corrosion cracking of Inconel alloy 600 in high-temperature water: an update. [PWR

    SciTech Connect

    Bandy, R.; van Rooyen, D.

    1983-01-01

    Inconel 600 has been tested in high-temperature aqueous media (without oxygen) in several tests. Data are presented to relate failure times to periods of crack initiation and propagation. Quantitative relationships have been developed from tests in which variations were made in temperature, applied load, strain rate, water chemistry, and the condition of the test alloy.

  10. Microstructure, Fatigue Behavior, and Failure Mechanisms of Direct Laser-Deposited Inconel 718

    NASA Astrophysics Data System (ADS)

    Johnson, Alex S.; Shao, Shuai; Shamsaei, Nima; Thompson, Scott M.; Bian, Linkan

    2017-03-01

    Inconel 718 is considered to be a superalloy with a series of superior properties such as high strength, creep resistance, and corrosion resistance at room and elevated temperatures. Additive manufacturing (AM) is particularly appealing to Inconel 718 because of its near-net-shape production capability for circumventing the poor machinability of this superalloy. Nevertheless, AM parts are prone to porosity, which is detrimental to their fatigue resistance. Thus, further understanding of their fatigue behavior is required before their widespread use in load-bearing applications. In this work, the microstructure and fatigue properties of AM Inconel 718, produced in a Laser Engineered Net Shaping (LENS™) system and heat treated with a standard heat treatment schedule, are evaluated at room temperature. Fully reversed strain controlled fatigue tests were performed on cylindrical specimens with straight gage sections at strain amplitudes ranging from 0.001 mm/mm to 0.01 mm/mm. The fracture surfaces of fatigue specimens were inspected with a scanning electron microscope. The results indicate that the employed heat treatment allowed the large, elongated grains and dendritic structure of the as-built material to break down into smaller, equiaxed grains, with some dendritic structures remaining between layers. The AM specimens were found to possess lower fatigue resistance than wrought Inconel 718, and this is primarily attributed to the presence of brittle metal-carbide/oxide inclusions or pores near their surface.

  11. Measurements in liquid fuel sprays

    NASA Technical Reports Server (NTRS)

    Chigier, N.

    1984-01-01

    Techniques for studying the events directly preceding combustion in the liquid fuel sprays are being used to provide information as a function of space and time on droplet size, shape, number density, position, angle of flight and velocity. Spray chambers were designed and constructed for: (1) air-assist liquid fuel research sprays; (2) high pressure and temperature chamber for pulsed diesel fuel sprays; and (3) coal-water slurry sprays. Recent results utilizing photography, cinematography, and calibration of the Malvern particle sizer are reported. Systems for simultaneous measurement of velocity and particle size distributions using laser Doppler anemometry interferometry and the application of holography in liquid fuel sprays are being calibrated.

  12. Hydrogen Permeability of Incoloy 800H, Inconel 617, and Haynes 230 Alloys

    SciTech Connect

    Pattrick Calderoni

    2010-07-01

    A potential issue in the design of the NGNP reactor and high-temperature components is the permeation of fission generated tritium and hydrogen product from downstream hydrogen generation through high-temperature components. Such permeation can result in the loss of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system. The issue will be addressed in the engineering design phase, and requires knowledge of permeation characteristics of the candidate alloys. Of three potential candidates for high-temperature components of the NGNP reactor design, the hydrogen permeability has been documented well only for Incoloy 800H, but at relatively high partial pressures of hydrogen. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. The hydrogen permeability of Haynes 230 has not been published. To support engineering design of the NGNP reactor components, the hydrogen permeability of Inconel 617 and Haynes 230 were determined using a measurement system designed and fabricated at the Idaho National Laboratory. The performance of the system was validated using Incoloy 800H as reference material, for which the permeability has been published in several journal articles. The permeability of Incoloy 800H, Inconel 617 and Haynes 230 was measured in the temperature range 650 to 950 °C and at hydrogen partial pressures of 10-3 and 10-2 atm, substantially lower pressures than used in the published reports. The measured hydrogen permeability of Incoloy 800H and Inconel 617 were in good agreement with published values obtained at higher partial pressures of hydrogen. The hydrogen permeability of Inconel 617 and Haynes 230 were similar, about 50% greater than for Incoloy 800H and with similar temperature dependence.

  13. High-temperature thermo-mechanical behavior of functionally graded materials produced by plasma sprayed coating: Experimental and modeling results

    NASA Astrophysics Data System (ADS)

    Choi, Kang Hyun; Kim, Hyun-Su; Park, Chang Hyun; Kim, Gon-Ho; Baik, Kyoung Ho; Lee, Sung Ho; Kim, Taehyung; Kim, Hyoung Seop

    2016-09-01

    Thermal barrier coatings are widely used in aerospace industries to protect exterior surfaces from harsh environments. In this study, functionally graded materials (FGMs) were investigated with the aim to optimize their high temperature resistance and strength characteristics. NiCrAlY bond coats were deposited on Inconel-617 superalloy substrate specimens by the low vacuum plasma spraying technique. Functionally graded Ni-yttria-stabilized zirconia (YSZ) coatings with gradually varying amounts of YSZ (20%-100%) were fabricated from composite powders by vacuum plasma spraying. Heat shield performance tests were conducted using a high- temperature plasma torch. The temperature distributions were measured using thermocouples at the interfaces of the FGM layers during the tests. A model for predicting the temperature at the bond coating-substrate interface was established. The temperature distributions simulated using the finite element method agreed well with the experimental results.

  14. Corrosion resistance of inconel 690 to borax, boric acid, and boron nitride at 1100{degrees}C

    SciTech Connect

    Imrich, K.J.

    1996-12-12

    Significant general and localized corrosion was observed on Inconel 690 coupons following exposure to borax, boric acid and boron nitride at 1100{degrees}C. Severe localized attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack (IGA) of the Inconel 690 was also observed. Severe internal void formation and IGA (30 mils penetration after 3 days) was observed in the coupon exposed to boric acid. Both borax and boric acid remove the protective chromium oxide; however, this layer can be reestablished by heating the Inconel 690 to 975 {degrees}C in air for several hours. Inconel 690 in direct contact with boron nitride resulted in the formation of a thick chromium borate layer, a general corrosion rate of 50 to 90 mils per year, and internal void formation of 1 mil per day.

  15. Miniature spray-painting booth

    NASA Technical Reports Server (NTRS)

    Fee, K. W.

    1970-01-01

    Transparent spray booth provides method for quality painting and repair of surfaces in clean room or other specialized environments. Overspray and virtually all contaminating vapor and odor can be eliminated. Touch-up painting is achieved with spray gun.

  16. Nasal spray flu vaccine (image)

    MedlinePlus

    The flu vaccine can also be administered as a nasal spray instead of the usual injection method. It can be ... the recombinant influenza vaccine (RIV). The nasal spray flu vaccine (live attenuated influenza vaccine or LAIV) should not ...

  17. Acoustic effects of sprays

    NASA Technical Reports Server (NTRS)

    Pindera, Maciej Z.; Przekwas, Andrzej J.

    1994-01-01

    Since the early 1960's, it has been known that realistic combustion models for liquid fuel rocket engines should contain at least a rudimentary treatment of atomization and spray physics. This is of particular importance in transient operations. It has long been recognized that spray characteristics and droplet vaporization physics play a fundamental role in determining the stability behavior of liquid fuel rocket motors. This paper gives an overview of work in progress on design of a numerical algorithm for practical studies of combustion instabilities in liquid rocket motors. For flexibility, the algorithm is composed of semi-independent solution modules, accounting for different physical processes. Current findings are report and future work is indicated. The main emphasis of this research is the development of an efficient treatment to interactions between acoustic fields and liquid fuel/oxidizer sprays.

  18. Development of thermally-sprayed Al-Cu-Fe-Cr quasicrystal coating

    NASA Astrophysics Data System (ADS)

    Setiamarga, Budi Hartono

    A class of quasicrystal alloys that has drawn a lot of attention is aluminum based quasicrystal alloys because they are hard, light weight, wear resistant, and have a non-stick property. Quasicrystalline materials in the form of coatings produced by thermal spray techniques have been developed to utilize their properties. The goal of this research has been to develop the knowledge necessary to produce good thermally sprayed Al-Cu-Fe-Cr quasicrystal coatings. Boron has been found to improve ductility, reduce porosity and increase hardness when added to other thermally sprayed powders, therefore, as part of this research, quasicrystal coatings containing boron will also be produced and evaluated. The first phase of this research utilized a fine QC-1 quasicrystal powder of Alsb{70.5}Cusb{10.1}Fesb{8.8}Crsb{10.6}. The addition of boron was done using mechanical mixing. The addition of boron in fused QC-1 powders shows that boron can reduce porosity and increase hardness. Due to difficulties with thermal spraying the fine QC-1 powder and evaporation of aluminum, a coarser QC-2 powder with similar composition to QC-1 powder was produced. QC-2 and boron modified QC-2 coatings have similar hardness and levels of porosity, around 11%, although boron modified QC-2 coatings proved to be more wear resistant than plain QC-2 coatings. Both coatings demonstrated a weak coating-substrate interface bonding. Laser heat treatment was used to reduce the porosity and strengthen the coating-substrate interface bonding. Laser treatment of QC-2 quasicrystal coatings resulted in harder and lower porosity coatings with better coating-substrate interface bonding. Unfortunately, hot-cracks in the coatings were also produced. Hot-cracks are undesireable because they decrease the coating's corrosion resistance. Thermal spraying using High Velocity Oxygen Fuel (HVOF) technique was done. It was used on QC-2 powder and QC-3 powder of composition Alsb{68.6}Cusb{10.8}Fesb{8.9}Crsb{9.7}Bsb{2.0}. This

  19. Effect of Orientation on Tensile Properties of Inconel 718 Block Fabricated with Electron Beam Freeform Fabrication (EBF3)

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Atherton, Todd S.

    2010-01-01

    Electron beam freeform fabrication (EBF3) direct metal deposition processing was used to fabricate an Inconel 718 bulk block deposit. Room temperature tensile properties were measured as a function of orientation and location within the block build. This study is a follow-on activity to previous work on Inconel 718 EBF3 deposits that were too narrow to allow properties to be measured in more than one orientation

  20. Controlled overspray spray nozzle

    NASA Technical Reports Server (NTRS)

    Prasthofer, W. P. (Inventor)

    1981-01-01

    A spray system for a multi-ingredient ablative material wherein a nozzle A is utilized for suppressing overspray is described. The nozzle includes a cyclindrical inlet which converges to a restricted throat. A curved juncture between the cylindrical inlet and the convergent portion affords unrestricted and uninterrupted flow of the ablative material. A divergent bell-shaped chamber and adjustable nozzle exit B is utilized which provides a highly effective spray pattern in suppressing overspray to an acceptable level and producing a homogeneous jet of material that adheres well to the substrate.

  1. Sprayed Coating Renews Butyl Rubber

    NASA Technical Reports Server (NTRS)

    Martin, R. B.

    1982-01-01

    Damaged butyl rubber products are renewed by spray technique originally developed for protective suits worn by NASA workers. A commercial two-part adhesive is mixed with Freon-113 (or equivalent) trichlorotrifluoroethane to obtain optimum viscosity for spraying. Mix is applied with an external-air-mix spray gun.

  2. Strength Differential Measured in Inconel 718: Effects of Hydrostatic Pressure Studied

    NASA Technical Reports Server (NTRS)

    Lewandowski, John J.; Wesseling, Paul; Prabhu, Nishad S.; Larose, Joel; Lissenden, Cliff J.; Lerch, Bradley A.

    2003-01-01

    Aeropropulsion components, such as disks, blades, and shafts, are commonly subjected to multiaxial stress states at elevated temperatures. Experimental results from loadings as complex as those experienced in service are needed to help guide the development of accurate viscoplastic, multiaxial deformation models that can be used to improve the design of these components. During a recent study on multiaxial deformation (ref. 1) on a common aerospace material, Inconel 718, it was shown that the material in the aged state exhibits a strength differential effect (SDE), whereby the uniaxial compressive yield and subsequent flow behavior are significantly higher than those in uniaxial tension. Thus, this material cannot be described by a standard von Mises yield formulation. There have been other formulations postulated (ref. 2) that involve other combinations of the stress invariants, including the effect of hydrostatic stress. The question remained as to which invariants are necessary in the flow model. To capture the physical mechanisms occurring during deformation and reflect them in the plasticity formulation, researchers examined the flow of Inconel 718 under various amounts of hydrostatic stress to determine whether or not hydrostatic stress is needed in the formulation. Under NASA Grant NCC3-464, monitored by the NASA Glenn Research Center, a series of tensile tests were conducted at Case Western Reserve University on aged (precipitation hardened) Inconel 718 at 650 C and with superimposed hydrostatic pressure. Dogbone shaped tensile specimens (3-mm-diameter gauge by 16-mm gauge length) and cylindrical compression specimens (3-mm-diameter gauge by 6-mm gauge length) were strain gauged and loaded in a high-pressure testing apparatus. Hydrostatic pressures were obtained with argon and ranged from 210 to 630 MPa. The aged Inconel 718 showed a pronounced difference in the tension and compression yield strength (i.e., an SDE), as previously observed. Also, there were

  3. Picosecond imaging of sprays

    NASA Technical Reports Server (NTRS)

    Breisacher, Kevin; Liou, Larry; Wang, L.; Liang, X.; Galland, P.; Ho, P. P.; Alfano, R. R.

    1994-01-01

    Preliminary results from applying a Kerr-Fourier imaging system to a water/air spray produced by a shear coaxial element are presented. The physics behind ultrafast time-gated optical techniques is discussed briefly. A typical setup of a Kerr-Fourier time gating system is presented.

  4. Oxymetazoline Nasal Spray

    MedlinePlus

    ... Rinse the tip of the dispenser with hot water or wipe it clean after you use it.Follow the directions for using the nasal spray that appear on the package label. If you are using a product that comes in a pump dispenser, press down on the rim several times ...

  5. Ocean Spray Lubricates Winds

    ERIC Educational Resources Information Center

    Journal of College Science Teaching, 2005

    2005-01-01

    According to a new study by two University of California, Berkeley, mathematicians and their Russian colleague, the water droplets kicked up by rough seas serve to lubricate the swirling winds of hurricanes and cyclones, letting them build to speeds approaching 200 miles per hour. Without the lubricating effect of the spray, the mathematicians…

  6. Ocean Spray Lubricates Winds

    ERIC Educational Resources Information Center

    Journal of College Science Teaching, 2005

    2005-01-01

    According to a new study by two University of California, Berkeley, mathematicians and their Russian colleague, the water droplets kicked up by rough seas serve to lubricate the swirling winds of hurricanes and cyclones, letting them build to speeds approaching 200 miles per hour. Without the lubricating effect of the spray, the mathematicians…

  7. Mometasone Nasal Spray

    MedlinePlus

    ... in cold water and rinse them in cold water, let them dry at room temperature, and then put them back on the bottle.If the spray tip is clogged, wash it in cold water and then rinse it in cold water and ...

  8. Spray combustion stability project

    NASA Technical Reports Server (NTRS)

    Jeng, San-Mou; Litchford, Ron J.

    1992-01-01

    This report summarizes research activity on the Spray Combustion Stability Project, characterizes accomplishments and current status, and discusses projected future work. The purpose is to provide a concise conceptual overview of the research effort to date so the reader can quickly assimilate the gist of the research results and place them within the context of their potential impact on liquid rocket engine design technology.

  9. Microstructure, Processing, Performance Relationships for High Temperature Coatings

    SciTech Connect

    Thomas M. Lillo

    2011-04-01

    This work evaluates the suitability of iron aluminide coatings for use in high temperature fossil fuel combustion environments, such as boiler applications. The coatings are applied using High Velocity Oxy-Fuel (HVOF) thermal spray techniques. Iron aluminide coatings, with the nominal composition of Fe3Al, were applied to various high temperature structural materials (316 Stainless Steel, 9Cr-1Mo steel and Inconel 600) that typically lack inherent resistance to environmental degradation found in fossil fuel combustion atmospheres. Coating/substrate combinations were subjected to thermal cycling to evaluate the effect of HVOF parameters, coating thickness, substrate material and substrate surface roughness on the resistance to coating delamination and cracking. It was found that substrate surface roughness had a profound influence on the performance of a given substrate/coating system and that surface preparation techniques will need to be tailored to the specific substrate material. Also, higher particle velocity during HVOF thermal spray deposition of the iron aluminide coatings tended to result in better-performing coating/substrate systems with less delamination at the coating/substrate interface. Some combinations of HVOF parameters, coating thickness and substrate materials were found to perform extremely well even at temperatures up to 900oC. However, in some cases, substantial reactions at the interface were observed.

  10. Study of In-Flight and Impact Dynamics of Nonspherical Particles from HVOF Guns

    NASA Astrophysics Data System (ADS)

    Kamnis, S.; Gu, S.

    2010-01-01

    High velocity oxygen fuel thermal spray has been widely used to deposit hard composite materials such as WC-Co powders for wear-resistant applications. Unlike gas atomized spherical powders, WC-CO powders form a more complex geometry. The knowledge gained from the existing spherical powders on process control and optimization may not be directly applicable to WC-Co coatings. This paper is the first to directly examine nonspherical particle in-flight dynamics and the impingement process on substrate using computational methods. Two sets of computational models are developed. First, the in-flight particles are simulated in the CFD-based combusting gas flow. The particle information prior to impact is extracted from the CFD results and implemented in a FEA model to dynamically track the impingement of particles on substrate. The morphology of particles is examined extensively including both spherical and nonspherical powders to establish the critical particle impact parameters needed for adequate bonding.

  11. Thermal spray for commercial shipbuilding

    NASA Astrophysics Data System (ADS)

    Rogers, F. S.

    1997-09-01

    Thermal spraying of steel with aluminum to protect it from corrosion is a technology that has been proven to work in the marine environment. The thermal spray coating system includes a paint sealer that is applied over the thermally sprayed aluminum. This extends the service life of the coating and provides color to the end product. The thermal spray system protects steel both through the principle of isolation (as in painting) and galvanizing. With this dual protection mechanism, steel is protected from corrosion even when the coating is damaged. The thermal- sprayed aluminum coating system has proved the most cost- effective corrosion protection system for the marine environment. Until recently, however, the initial cost of application has limited its use for general application. Arc spray technology has reduced the application cost of thermal spraying of aluminum to below that of painting. Commercial shipbuilders could use this technology to enhance their market position in the marine industry.

  12. Effects of heat input on the pitting resistance of Inconel 625 welds by overlay welding

    NASA Astrophysics Data System (ADS)

    Kim, Jun Seok; Park, Young IL; Lee, Hae Woo

    2015-03-01

    The objective of this study was to establish the relationship between the dilution ratio of the weld zone and pitting resistance depending on the heat input to welding of the Inconel alloy. Each specimen was produced by electroslag welding using Inconel 625 as the filler metal. In the weld zone of each specimen, dendrite grains were observed near the fusion line and equiaxed grains were observed on the surface. It was also observed that a melted zone with a high Fe content was formed around the fusion line, which became wider as the welding heat input increased. In order to evaluate the pitting resistance, potentiodynamic polarization tests and CPT tests were conducted. The results of these tests confirmed that there is no difference between the pitting resistances of each specimen, as the structures of the surfaces were identical despite the effect of the differences in the welding heat input for each specimen and the minor dilution effect on the surface.

  13. Nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel and stainless steel alloys

    SciTech Connect

    Moore, D.G.; Sorensen, N.R.

    1998-02-01

    This report presents a nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning techniques to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each technique classifies a known exhaust material. Results indicate that either inspection technique can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into the Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.

  14. Fatigue behavior of two alloys for Space Shuttle applications. [Inconel 903 and 718 for main engine

    NASA Technical Reports Server (NTRS)

    Adsit, N. R.; Block, S. J.

    1978-01-01

    Two superalloys used extensively in the Space Shuttle main engine are Incoloy 903 and Inconel 718. The fatigue behavior of the two alloys under varying conditions is considered. Three heats of Incoloy 903 and two of Inconel 718 were used in the study. Material was tested in several conditions, including mill polish, longitudinal mill polish, transverse mill polish, chemically milled, chemically milled plus shotpeened on one side and on both sides, gas tungsten arc welded, and electron beam welded. Both round and flat tensile specimens were tested in universal test machines. It was found that surface condition influences test results. Transverse scratches resulting from polishing and rougher surfaces lower the stress at runout in relation to that obtained on longitudinally polished and/or smooth-surfaced specimens.

  15. Experimental and numerical heat transfer studies on quenching of Inconel 600 probe

    NASA Astrophysics Data System (ADS)

    Ramesh, G.; Narayan Prabhu, K.

    2015-01-01

    The effect of heat transfer coefficient and quench start temperature on cooling behaviour of Inconel 600 quench probe was assessed by numerical experiments. A quantitative model that relates the mean cooling rate and quench start temperature of the probe with the boundary heat transfer coefficient was proposed. Computed aided cooling curve analysis was carried out by heating Inconel 600 probe to temperatures varying from 100 to 850 °C followed by quenching in water. The results of quenching experiments and the data available in the literature were used to validate the proposed model. A good agreement between the measured and estimated value was observed. The results showed that the film and transition boiling of cooling stages were significantly influenced by quench start temperature of the material while nucleate boiling and convective cooling stages were strongly dependent on the boundary heat transfer coefficient.

  16. Laser Additive Melting and Solidification of Inconel 718: Finite Element Simulation and Experiment

    NASA Astrophysics Data System (ADS)

    Romano, John; Ladani, Leila; Sadowski, Magda

    2016-03-01

    The field of powdered metal additive manufacturing is experiencing a surge in public interest finding uses in aerospace, defense, and biomedical industries. The relative youth of the technology coupled with public interest makes the field a vibrant research topic. The authors have expanded upon previously published finite element models used to analyze the processing of novel engineering materials through the use of laser- and electron beam-based additive manufacturing. In this work, the authors present a model for simulating fabrication of Inconel 718 using laser melting processes. Thermal transport phenomena and melt pool geometries are discussed and validation against experimental findings is presented. After comparing experimental and simulation results, the authors present two correction correlations to transform the modeling results into meaningful predictions of actual laser melting melt pool geometries in Inconel 718.

  17. Enhanced field emission properties from CNT arrays synthesized on Inconel superalloy.

    PubMed

    Sridhar, S; Ge, L; Tiwary, C S; Hart, A C; Ozden, S; Kalaga, K; Lei, S; Sridhar, S V; Sinha, R K; Harsh, H; Kordas, K; Ajayan, P M; Vajtai, R

    2014-02-12

    One of the most promising materials for fabricating cold cathodes for next generation high-performance flat panel devices is carbon nanotubes (CNTs). For this purpose, CNTs grown on metallic substrates are used to minimize contact resistance. In this report, we compare properties and field emission performance of CNTs grown via water assisted chemical vapor deposition using Inconel vs silicon (Si) substrates. Carbon nanotube forests grown on Inconel substrates are superior to the ones grown on silicon; low turn-on fields (∼1.5 V/μm), high current operation (∼100 mA/cm(2)) and very high local field amplification factors (up to ∼7300) were demonstrated, and these parameters are most beneficial for use in vacuum microelectronic applications.

  18. Investigation of Machine-ability of Inconel 800 in EDM with Coated Electrode

    NASA Astrophysics Data System (ADS)

    Karunakaran, K.; Chandrasekaran, M.

    2017-03-01

    The Inconel 800 is a high temperature application alloy which is classified as a nickel based super alloy. It has wide scope in aerospace engineering, gas Turbine etc. The machine-ability studies were found limited on this material. Hence This research focuses on machine-ability studies on EDM of Inconel 800 with Silver Coated Electrolyte Copper Electrode. The purpose of coating on electrode is to reduce tool wear. The factors pulse on Time, Pulse off Time and Peck Current were considered to observe the responses of surface roughness, material removal rate, tool wear rate. Taguchi Full Factorial Design is employed for Design the experiment. Some specific findings were reported and the percentage of contribution of each parameter was furnished

  19. Diffusion bonding of a superplastic Inconel 718SPF superalloy by electroless nickel plating

    SciTech Connect

    Yeh, M.S.; Chang, C.B.; Chuang, T.H.

    2000-02-01

    Although intimate contact can be obtained for diffusion bonding of a superplastic Inconel 718SPF superalloy under a low pressure of 7 MPa, the precipitates formed at the interface retarded achievement of a sound joint. The shear strength was only 41.5 MPa for an overlap length of 12 T (T = 1.3 mm, sheet thickness). The diffusion bondability of t his Inconel 718SPF superalloy was enhanced by electroless nickel plating. In this situation, the bonding shear strength increased to 70.4 MPa for the same overlap length of 12 T under the same bonding condition, regardless of the roughness of the surface to be bonded. Upon decreasing the overlap length from 12 to 6T, the bonding strength remained constant.

  20. Influence Of The Laser Cladding Strategies On The Mechanical Properties Of Inconel 718

    SciTech Connect

    Lamikiz, A.; Tabernero, I.; Ukar, E.; Lopez de Lacalle, L. N.

    2011-01-17

    This work presents different experimental results of the mechanical properties of Inconel registered 718 test parts built-up by laser cladding. Recently, turbine manufacturers for aeronautical sector have presented high interest on laser cladding processes. This process allows building fully functional structures on superalloys, such as Inconel registered 718, with high flexibility on complex shapes. However, there is limited data on mechanical properties of the laser cladding structures. Moreover, the available data do not include the influence of process parameters and laser cladding strategies. Therefore, a complete study of the influence of the laser cladding parameters and mainly, the variation of the tensile strength with the laser cladding strategy is presented. The results show that there is a high directionality of mechanical properties, depending on the strategies of laser cladding process. In other words, the test parts show a fiber -like structure that should be considered on the laser cladding strategy selection.

  1. Influence Of The Laser Cladding Strategies On The Mechanical Properties Of Inconel 718

    NASA Astrophysics Data System (ADS)

    Lamikiz, A.; Tabernero, I.; Ukar, E.; López de Lacalle, L. N.; Delgado, J.

    2011-01-01

    This work presents different experimental results of the mechanical properties of Inconel® 718 test parts built-up by laser cladding. Recently, turbine manufacturers for aeronautical sector have presented high interest on laser cladding processes. This process allows building fully functional structures on superalloys, such as Inconel® 718, with high flexibility on complex shapes. However, there is limited data on mechanical properties of the laser cladding structures. Moreover, the available data do not include the influence of process parameters and laser cladding strategies. Therefore, a complete study of the influence of the laser cladding parameters and mainly, the variation of the tensile strength with the laser cladding strategy is presented. The results show that there is a high directionality of mechanical properties, depending on the strategies of laser cladding process. In other words, the test parts show a fiber -like structure that should be considered on the laser cladding strategy selection.

  2. New technique for installing screen wicking into Inconel 718 heat pipe

    NASA Astrophysics Data System (ADS)

    Giriunas, Julius A.; Watson, Gordon K.; Tower, Leonard K.

    1993-01-01

    The creep behavior of superalloys, including Inconel 718, in the presence of liquid sodium is not yet known. To study this problem, the NASA Lewis Research Center has initiated a program with the Energy Technology Engineering Center (ETEC) of Rockwell International Corporation to fill with sodium and creep-test three small cylindrical heat pipes of Inconel 718 for a period of 1000 hours each. This report documents the design and the construction methods that were used at NASA Lewis to fabricate these heat pipes. Of particular importance in the heat pipe construction was the installation of the screen wicking by using an expandable mandrel and differential thermal expansion. This installation technique differs from anything known to have been reported in the heat pipe literature and may be of interest to other workers in the heat pipe field.

  3. New technique for installing screen wicking into Inconel 718 heat pipe

    SciTech Connect

    Giriunas, J.A.; Watson, G.K. ); Tower, L.K. )

    1993-01-10

    The creep behavior of superalloys, including Inconel 718, in the presence of liquid sodium is not yet known. To study this problem, the NASA Lewis Research Center has initiated a program with the Energy Technology Engineering Center (ETEC) of Rockwell International Corporation to fill with sodium and creep-test three small cylindrical heat pipes of Inconel 718 for a period of 1000 hours each. This report documents the design and the construction methods that were used at NASA Lewis to fabricate these heat pipes. Of particular importance in the heat pipe construction was the installation of the screen wicking by using an expandable mandrel and differential thermal expansion. This installation technique differs from anything known to have been reported in the heat pipe literature and may be of interest to other workers in the heat pipe field.

  4. Fatigue Crack Growth Rate of Inconel 718 Sheet at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Wells, Douglas; Wright, Jonathan; Hastings, Keith

    2005-01-01

    Inconel 718 sheet material was tested to determine fatigue crack growth rate (FCGR) at cryogenic conditions representative of a liquid hydrogen (LH2) environment at -423 degree F. Tests utilized M(T) and ESE(T) specimen geometries and environments were either cold gaseous helium or submersion in LH2. The test results support a significant improvement in the fatigue crack growth threshold at -423 degree F compared to -320 degree F or 70 degree F.

  5. High temperature environmental interactions of Inconel 617: A paper study for the TEF

    SciTech Connect

    Korinko, P.S.

    2000-06-16

    Inconel alloy 617 has been selected as the material of choice for the retort of the furnace for the Tritium Extraction Facility. To monitor retort performance and suitability for continued service, representative sample coupons should be suspended on the inside (process side) and outside (annulus side) of the retort for periodic metallographic analysis or hardness testing. Surface dealloying and hardness could be used to monitor the ``health'' of the retort in this surveillance program.

  6. Improved Orifice Plate for Spray Gun

    NASA Technical Reports Server (NTRS)

    Cunningham, W.

    1986-01-01

    Erratic spray pattern of commercial spray gun changed to repeatable one by simple redesign of two parts. In modified spray gun orifice plate and polytetrafluoroethylene bushing redesigned to assure centering and alignment with nozzle. Such improvement useful in many industrial applications requiring repeatable spray patterns. Might include spraying of foam insulation, paint, other protective coatings, detergents, abrasives, adhesives, process chemicals, or fuels. Unmodified spray gun produces erratic spray because lateral misalignment between orifice plate and nozzle.

  7. Improved Orifice Plate for Spray Gun

    NASA Technical Reports Server (NTRS)

    Cunningham, W.

    1986-01-01

    Erratic spray pattern of commercial spray gun changed to repeatable one by simple redesign of two parts. In modified spray gun orifice plate and polytetrafluoroethylene bushing redesigned to assure centering and alignment with nozzle. Such improvement useful in many industrial applications requiring repeatable spray patterns. Might include spraying of foam insulation, paint, other protective coatings, detergents, abrasives, adhesives, process chemicals, or fuels. Unmodified spray gun produces erratic spray because lateral misalignment between orifice plate and nozzle.

  8. Optimisation of a vertical spray boom for greenhouse spraying applications.

    PubMed

    Nuyttens, D; Windey, S; Braekman, P; De Moor, A; Sonck, B

    2003-01-01

    The European Crop Protection Association (ECPA) and CLO-DVL joined forces in a project to stimulate a safe use of pesticides in Southern European countries. CLO-DVL optimised a method with mineral chelates to evaluate deposition tests. This quantitative method to evaluate spray deposits and to check spray distributions is used to assess two novel spraying techniques. Deposition tests with water-sensitive paper and mainly with the manganese and molybdenum chelates as tracer elements were performed with a manually pulled trolley and a motorised vehicle both equipped with vertical spray booms. Filter papers were attached to the tomato and pepper plants at several heights to obtain an indication of the spray distribution in the crop. Particular attention was paid to the effect on the spray distribution of the vertical nozzle distance (35 cm vs. 50 cm) and the spray distance to the crop. The tests proved that a nozzle spacing of 35 cm delivers a much better spray distribution than one of 50 cm. The optimal spray distance for flat fan nozzles with a spray angle of 80 degrees and a nozzle spacing of 35 cm is about 30 cm.

  9. Evaluation of hot corrosion of 8YSZ coatings elaborated by suspension plasma spraying

    NASA Astrophysics Data System (ADS)

    González-Hernández, A. G.; Ageorges, H.; López-Gómez, M. E.

    2017-01-01

    In this paper, the evaluation microscopic of hot corrosion of 8mol% Yttria Stabilized Zirconia (8YSZ) coatings was studied in the presence of V2O5 and Na2SO4 as corrosive molten salt, for 40h at 1050°C. First, the substrates of Inconel 718 super-alloy were sprayed with a NiCrCoAl-Y2O3 bond coat by atmospheric plasma spraying (APS). Then this bond coat was polished for elaborated the 8YSZ layer by suspension plasma spraying (SPS). The microstructure of the cross-section and surface of the coating was evaluated by scanning electron microscopy (SEM). After the hot corrosion test, the delamination of 8YSZ coatings was occurred in the ceramic layer due to the creation of stress resulting from the chemical reaction between the molten salts and the yttria (Y2O3) of 8YSZ coating at high temperature. According to EDS-SEM analysis, the evaluation of fractured sections of 8YSZ coating showed mainly the formation of crystals composed by Y, V, O and the surface was mainly composed by Zr and O. Those crystals can be related with the tetragonal phase of YVO4, which they were commonly found by other researchers in studies of hot corrosion of YSZ-based TBCs when its surface reacts with the corrosive salts.

  10. Structural and Tribological Properties of Nanostructured Supersonic Cold Sprayed Ni-20 wt.% Sn Coatings

    NASA Astrophysics Data System (ADS)

    Georgiou, E. P.; Dosta, S.; Fernández, J.; Matteazzi, P.; Kowalski, K.; Kusinski, J.; Piticescu, R. R.; Celis, J.-P.

    2016-06-01

    80-μm-thick nanostructured coatings consisting of a Ni solid solution, Ni3Sn, Ni3Sn2, and metastable NiSn intermetallic phases were deposited via supersonic cold spraying onto inconel 718 alloy substrates. These coatings have complex nanostructured metallurgical phases as revealed by transition electron microscopy, scanning electron microscopy, and x-ray diffraction techniques. Their mechanical properties were determined by nanoindentation measurements. Furthermore, the wear behavior of these nanostructured sprayed coatings was compared to the one of the industrial bulk or sprayed coated benchmark materials. It was found that the nanostructured coatings exhibit higher wear resistance than the industrial benchmarks, thanks to an appropriate balance of hard intermetallic phases and soft Ni matrix, as well as to their nanostructuring. Their frictional characteristics under reciprocating sliding are mainly determined by the formation of an oxide-based tribo-layer, which was analyzed by x-ray photoelectron spectroscopy. The role of intermetallic phases in these coatings on the friction and wear is also discussed.

  11. Elastoplastic analysis of process induced residual stresses in thermally sprayed coatings

    SciTech Connect

    Chen Yongxiong; Liang Xiubing; Liu Yan; Xu Binshi

    2010-07-15

    The residual stresses induced from thermal spraying process have been extensively investigated in previous studies. However, most of such works were focused on the elastic deformation range. In this paper, an elastoplastic model for predicting the residual stresses in thermally sprayed coatings was developed, in which two main contributions were considered, namely the deposition induced stress and that due to differential thermal contraction between the substrate and coating during cooling. The deposition induced stress was analyzed based on the assumption that the coating is formed layer-by-layer, and then a misfit strain is accommodated within the multilayer structure after the addition of each layer (plastic deformation is induced consequently). From a knowledge of specimen dimensions, processing temperatures, and material properties, residual stress distributions within the structure can be determined by implementing the model with a simple computer program. A case study for the plasma sprayed NiCoCrAlY on Inconel 718 system was performed finally. Besides some similar phenomena observed from the present study as compared with previous elastic model reported in literature, the elastoplastic model also provides some interesting features for prediction of the residual stresses.

  12. The deformation and fracture characteristics of inconel X-750 at room temperature and elevated temperatures

    NASA Astrophysics Data System (ADS)

    Mills, W. J.

    1980-06-01

    Electron fractographic and thin foil electron metallographic techniques were used to evaluate the deformation and fracture characteristics of Inconel X-750 at temperatures ranging from 24 to 816 °C. Operative dislocation mechanisms and fracture surface morphologies were related to the overall tensile response of this nickel-base superalloy. At room temperature, failure occurred primarily by an intergranular dimple rupture mechanism associated with microvoid coalescence along grain boundary denuded regions. A fairly high density of dislocations throughout the matrix resulted in relatively high ductility levels even though failure occurred by an intergranular mechanism. Under intermediate temperature conditions (316 to 427 °C), increased transgranular fracture coupled with extensive dislocation activity within the Inconel X-750 matrix caused a slight increase in ductility. At progressively higher temperatures, 538 to 704 °C, all dislocation activity was channeled through narrow slip bands which subsequently initiated localized separation and resulted in a very faceted fracture surface appearance. The absence of a homogeneous dislocation substructure in this temperature regime resulted in a severe degradation in ductility levels. At the highest test temperature (816 °C), a uniform dislocation network throughout the Inconel X-750 matrix coupled with intense dislocation activity in the grain boundary denuded zone resulted in a marked improvement in ductility. Furthermore, the extensive dislocation activity along grain boundary regions ultimately resulted in an intergranular fracture morphology.

  13. Microstructure Development in Electron Beam-Melted Inconel 718 and Associated Tensile Properties

    SciTech Connect

    Kirka, M. M.; Unocic, K. A.; Raghavan, N.; Medina, F.; Dehoff, R. R.; Babu, S. S.

    2016-02-12

    During the electron beam melting (EBM) process, builds occur at temperatures in excess of 800°C for nickel-base superalloys such as Inconel 718. When coupled with the temporal differences between the start and end of a build, a top-to-bottom microstructure gradient forms. Characterized in this study is the microstructure gradient and associated tensile property gradient that are common to all EBM Inconel 718 builds. From the characteristic microstructure elements observed in EBM Inconel 718 material, the microstructure gradient can be classified into three distinct regions. Region 1 (top of a build) and is comprised of a cored dendritic structure that includes carbides and Laves phase within the interdendritic regions. Region 2 is an intermediate transition zone characterized by a diffuse dendritic structure, dissolution of the Laves phase, and precipitation of δ needle networks within the interdendritic regions. The bulk structure (Region 3) is comprised of a columnar grain structure lacking dendritic characteristics with δ networks having precipitated within the grain interiors. Mechanically at both 20°C and 650° C, the yield strength, ultimate tensile strength, and elongation at failure exhibit the general trend of increasing with increasing build height.

  14. Process Capability of High Speed Micro End-Milling of Inconel 718 with Minimum Quantity Lubrication

    NASA Astrophysics Data System (ADS)

    Rahman, Mohamed Abd; Yeakub Ali, Mohammad; Rahman Shah Rosli, Abdul; Banu, Asfana

    2017-03-01

    The demand for micro-parts is expected to grow and micro-machining has been shown to be a viable manufacturing process to produce these products. These micro-products may be produced from hard-to-machine materials such as superalloys under little or no metal cutting fluids to reduce machining cost or drawbacks associated with health and environment. This project aims to investigate the capability of micro end-milling process of Inconel 718 with minimum quantity lubrication (MQL). Microtools DT-110 multi-process micro machine was used to machine 10 micro-channels with MQL and 10 more under dry condition while maintaining the same machining parameters. The width of the micro-channels was measured using digital microscope and used to determine the process capability indices, Cp and Cpk. QI Macros SPC for Excel was used to analyze the resultant machining data. The results indicated that micro end-milling process of Inconel 718 was not capable under both MQL and dry cutting conditions as indicated by the Cp values of less than 1.0. However, the use of MQL helped the process to be more stable and capable. Results obtained showed that the process variation was greatly reduced by using MQL in micro end-milling of Inconel 718.

  15. High temperature joint properties with palladium alloys for SUS316L and Inconel 600

    SciTech Connect

    Izui, Hiroshi; Suezawa, Yoshifumi

    1995-12-31

    Newly developed Pd-Ag-Mn system braze alloys were considered for use in brazing stainless steel SUS316L or Ni-based alloy Inconel 600 for engine applications. Palladium braze alloys were selected because of their oxidation resistance, ductility, relatively high melting points, and lower cost than gold-based braze alloys. The reactions and microstructures were studied in experimental brazed joints between these base metals and the braze alloys. Tensile tests of the joints were carried out at room temperature, 473K, 673K, 873K, and 1,073K. The maximum tensile strengths of the joints brazed with 30Pd-60Ag-10Co at room temperature were 445MPa in the SUS316L joints and 456MPa in the Inconel 600 brazed joints. The SUS316L joints brazed with the braze alloys had tensile strengths of 320MPa to 200MPa from 473K to 1,73K. The Inconel 600 joints brazed with the 30Pd-50Ag-10Mn-10Co alloy had tensile strengths of 289MPa to 162MPa from 473K to 1,073K.

  16. Investigation of low stress rupture properties in Inconel-718 super alloy

    NASA Astrophysics Data System (ADS)

    Zaman, T.; Farooque, M.; Rizvi, S. A.; Salam, I.; Waseem, M.

    2016-08-01

    Inconel-718 is a Ni-Cr-Fe based super alloy. It is widely utilized in aircraft gas turbines, nuclear power systems, space vehicles and medical applications. Aim of the present study is to evaluate the effect of Ti and Nb content on high temperature stress rupture properties of Inconel718. OM, SEM and TEM were utilized for characterization of microstructure. Inconel718 is unique in that it forms large number of phases due to its composition and variety of heat treatments. γ"+ γ' precipitates and the effect of annealing on these precipitates have been studied using TEM. The main hardening phase was identified as metastable Ni3Nb (γ"). Other phases identified after annealing were secondary carbides (NbC) and stable acicular 5 phase. Effect of γ", 5, primary carbides and NbC on creep behavior was observed using OM and SEM. Higher Ti content(1.25 wt. %) resulted in poor creep properties due to large concentrations of primary carbides (TiC) at grain boundaries.

  17. Microstructure Development in Electron Beam-Melted Inconel 718 and Associated Tensile Properties

    NASA Astrophysics Data System (ADS)

    Kirka, M. M.; Unocic, K. A.; Raghavan, N.; Medina, F.; Dehoff, R. R.; Babu, S. S.

    2016-03-01

    During the electron beam melting (EBM) process, builds occur at temperatures in excess of 800°C for nickel-base superalloys such as Inconel 718. When coupled with the temporal differences between the start and end of a build, a top-to-bottom microstructure gradient forms. Characterized in this study is a microstructure gradient and associated tensile property gradient common to all EBM Inconel 718 builds, the extent of which is dependent on build geometry and the specifics of a build's processing history. From the characteristic microstructure elements observed in EBM Inconel 718 material, the microstructure gradient can be classified into three distinct regions. Region 1 (top of a build) is comprised of a cored dendritic structure that includes carbides and Laves phase within the interdendritic regions. Region 2 is an intermediate transition zone characterized by a diffuse dendritic structure, dissolution of the Laves phase, and precipitation of δ needle networks within the interdendritic regions. The bulk structure (Region 3) is comprised of a columnar grain structure lacking dendritic characteristics with δ networks having precipitated within the grain interiors. Mechanically, at both 20°C and 650°C, the yield strength, ultimate tensile strength, and elongation at failure exhibit the general trend of increasing with increasing build height.

  18. Surface Integrity of Inconel 718 by Wire-EDM at Different Energy Modes

    NASA Astrophysics Data System (ADS)

    Li, L.; Wei, X. T.; Guo, Y. B.; Li, W.; Liu, J. F.

    2014-08-01

    Inconel alloys including IN 718 alloy are widely used in turbomachinery industry due to their superior mechanical properties. Inconel alloys are very difficult to machine using cutting and grinding. Wire electrical discharge machining (W-EDM) is an alternative process to manufacture complex Inconel parts. However, little research has been done on surface integrity by W-EDMed IN 718. This study focuses on surface integrity of IN 718 by W-EDM at different modes of discharge energy. The results show that the EDMed surface topography shows dominant coral reef microstructures at high energy mode, while random microvoids are dominant at low energy modes. The average roughness can be significantly reduced at low energy mode. A thick white layer is predominantly discontinuous and non-uniform at relative high energy modes. Microvoids are confined within the thick white layers and no microcracks were found in the subsurface. A thin white layer by trim cut at low energy mode becomes continuous, uniform, and is free of voids. Compared to the bulk, white layers have dramatic reduction in microhardness. In addition, surface alloying from wire electrode and water dielectric is obvious in main cut, but it can be minimized in trim cuts.

  19. FLiNaK Compatability Studies with Inconel 600 and Silicon Carbide

    SciTech Connect

    Yoder, Jr, Graydon L.; Heatherly, Dennis Wayne; Wilson, Dane F.; Caja, Mario

    2016-07-26

    A small liquid fluoride salt test apparatus has been constructed and testing conducted to examine the compatibility of SiC, Inconel 600, and a spiral wound gasket material in FLiNaK salt. These tests were conducted to test materials and sealing systems that would be used in a FLiNaK salt test loop. Three months of testing at 700oC was used to assure that these materials and seals would be acceptable operating under expected test loop conditions. The SiC specimens showed little or no change over the test period while the spiral wound gasket material showed no degradation, except for the possibility of salt seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 m in depth. Analysis indicated that the salt had leached chrome from the Inconel surface as was expected for this material. Because the test loop will have a limited working lifetime, it was concluded that these materials would be satisfactory for loop construction.

  20. Effects of Flux Precoating and Process Parameter on Welding Performance of Inconel 718 Alloy TIG Welds

    NASA Astrophysics Data System (ADS)

    Lin, Hsuan-Liang; Wu, Tong-Min; Cheng, Ching-Min

    2014-01-01

    The purpose of this study is to investigate the effect of activating flux on the depth-to-width ratio (DWR) and hot cracking susceptibility of Inconel 718 alloy tungsten inert gas (TIG) welds. The Taguchi method is employed to investigate the welding parameters that affect the DWR of weld bead and to achieve optimal conditions in the TIG welds that are coated with activating flux in TIG (A-TIG) process. There are eight single-component fluxes used in the initial experiment to evaluate the penetration capability of A-TIG welds. The experimental results show that the Inconel 718 alloy welds precoated with 50% SiO2 and 50% MoO3 flux were provided with better welding performance such as DWR and hot cracking susceptibility. The experimental procedure of TIG welding process using mixed-component flux and optimal conditions not only produces a significant increase in DWR of weld bead, but also decreases the hot cracking susceptibility of Inconel 718 alloy welds.

  1. Experimental Investigation of process parameters influence on machining Inconel 800 in the Electrical Spark Eroding Machine

    NASA Astrophysics Data System (ADS)

    Karunakaran, K.; Chandrasekaran, M.

    2016-11-01

    The Electrical Spark Eroding Machining is an entrenched sophisticated machining process for producing complex geometry with close tolerances in hard materials like super alloy which are extremely difficult-to-machine by using conventional machining processes. It is sometimes offered as a better alternative or sometimes as an only alternative for generating accurate 3D complex shapes of macro, micro and nano-features in such difficult-to-machine materials among other advanced machining processes. The accomplishment of such challenging task by use of Electrical Spark Eroding Machining or Electrical Discharge Machining (EDM) is depending upon selection of apt process parameters. This paper is about analyzing the influencing of parameter in electrical eroding machining for Inconel 800 with electrolytic copper as a tool. The experimental runs were performed with various input conditions to process Inconel 800 nickel based super alloy for analyzing the response of material removal rate, surface roughness and tool wear rate. These are the measures of performance of individual experimental value of parameters such as pulse on time, Pulse off time, peak current. Taguchi full factorial Design by using Minitab release 14 software was employed to meet the manufacture requirements of preparing process parameter selection card for Inconel 800 jobs. The individual parameter's contribution towards surface roughness was observed from 13.68% to 64.66%.

  2. Laser cladding of Inconel 625-based composite coatings reinforced by porous chromium carbide particles

    NASA Astrophysics Data System (ADS)

    Janicki, Damian

    2017-09-01

    Inconel 625/Cr3C2 composite coatings were produced via a laser cladding process using Cr3C2 reinforcing particles presenting an open porosity of about 60%. A laser cladding system used consisted of a direct diode laser with a rectangular beam spot and the top-hat beam profile, and an off-axis powder injection nozzle. The microstructural characteristics of the coatings was investigated with the use of scanning electron microscopy and X-ray diffraction. A complete infiltration of the porous structure of Cr3C2 reinforcing particles and low degree of their dissolution have been achieved in a very narrow range of processing parameters. Crack-free composite coatings having a uniform distribution of the Cr3C2 particles and their fraction up to 36 vol% were produced. Comparative erosion tests between the Inconel 625/Cr3C2 composite coatings and the metallic Inconel 625 coatings were performed following the ASTM G 76 standard test method. It was found that the composite coatings have a significantly higher erosion resistance to that of metallic coatings for both 30° and 90° impingement angles. Additionally, the erosion performances of composite coatings were similar for both the normal and oblique impact conditions. The erosive wear behaviour of composite coatings is discussed and related to the unique microstructure of these coatings.

  3. Microstructure Development in Electron Beam-Melted Inconel 718 and Associated Tensile Properties

    DOE PAGES

    Kirka, M. M.; Unocic, K. A.; Raghavan, N.; ...

    2016-02-12

    During the electron beam melting (EBM) process, builds occur at temperatures in excess of 800°C for nickel-base superalloys such as Inconel 718. When coupled with the temporal differences between the start and end of a build, a top-to-bottom microstructure gradient forms. Characterized in this study is the microstructure gradient and associated tensile property gradient that are common to all EBM Inconel 718 builds. From the characteristic microstructure elements observed in EBM Inconel 718 material, the microstructure gradient can be classified into three distinct regions. Region 1 (top of a build) and is comprised of a cored dendritic structure that includesmore » carbides and Laves phase within the interdendritic regions. Region 2 is an intermediate transition zone characterized by a diffuse dendritic structure, dissolution of the Laves phase, and precipitation of δ needle networks within the interdendritic regions. The bulk structure (Region 3) is comprised of a columnar grain structure lacking dendritic characteristics with δ networks having precipitated within the grain interiors. Mechanically at both 20°C and 650° C, the yield strength, ultimate tensile strength, and elongation at failure exhibit the general trend of increasing with increasing build height.« less

  4. FLiNaK Compatability Studies with Inconel 600 and Silicon Carbide

    SciTech Connect

    Yoder, Jr, Graydon L.; Heatherly, Dennis Wayne; Wilson, Dane F.; Caja, Mario

    2016-07-26

    A small liquid fluoride salt test apparatus has been constructed and testing conducted to examine the compatibility of SiC, Inconel 600, and a spiral wound gasket material in FLiNaK salt. These tests were conducted to test materials and sealing systems that would be used in a FLiNaK salt test loop. Three months of testing at 700oC was used to assure that these materials and seals would be acceptable operating under expected test loop conditions. The SiC specimens showed little or no change over the test period while the spiral wound gasket material showed no degradation, except for the possibility of salt seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 m in depth. Analysis indicated that the salt had leached chrome from the Inconel surface as was expected for this material. Because the test loop will have a limited working lifetime, it was concluded that these materials would be satisfactory for loop construction.

  5. FLiNaK Compatability Studies with Inconel 600 and Silicon Carbide

    DOE PAGES

    Yoder, Jr, Graydon L.; Heatherly, Dennis Wayne; Wilson, Dane F.; ...

    2016-07-26

    A small liquid fluoride salt test apparatus has been constructed and testing conducted to examine the compatibility of SiC, Inconel 600, and a spiral wound gasket material in FLiNaK salt. These tests were conducted to test materials and sealing systems that would be used in a FLiNaK salt test loop. Three months of testing at 700oC was used to assure that these materials and seals would be acceptable operating under expected test loop conditions. The SiC specimens showed little or no change over the test period while the spiral wound gasket material showed no degradation, except for the possibility ofmore » salt seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 m in depth. Analysis indicated that the salt had leached chrome from the Inconel surface as was expected for this material. Because the test loop will have a limited working lifetime, it was concluded that these materials would be satisfactory for loop construction.« less

  6. Microstructure and Properties of Thermally Sprayed Functionally Graded Coatings for Polymeric Substrates

    NASA Technical Reports Server (NTRS)

    Ivosevic, M.; Knight, R.; Kalidindi, S. R.; Palmese, G. R.; Sutter, J. K.

    2003-01-01

    The use of polymer matrix composites (PMCs) in the gas flow path of advanced turbine engines offers significant benefits for aircraft engine performance but their useful lifetime is limited by their poor erosion resistance. High velocity oxy-fuel (HVOF) sprayed polymer/cermet functionally graded (FGM) coatings are being investigated as a method to address this technology gap by providing erosion and oxidation protection to polymer matrix composites. The FGM coating structures are based on a polyimide matrix filled with varying volume fractions of WC-Co. The graded coating architecture was produced using a combination of internal and external feedstock injection, via two computer-controlled powder feeders and controlled substrate preheating. Porosity, coating thickness and volume fraction of the WC-Co filler retained in the coatings were determined using standard metallographic techniques and computer image analysis. The pull-off strength (often referred to as the adhesive strength) of the coatings was evaluated according to the ASTM D 4541 standard test method, which measured the greatest normal tensile force that the coating could withstand. Adhesive/cohesive strengths were determined for three different types of coating structures and compared based on the maximum indicated load and the surface area loaded. The nature and locus of the fractures were characterized according to the percent of adhesive and/or cohesive failure, and the tested interfaces and layers involved were analyzed by Scanning Electron Microscopy.

  7. Laser surface modification (LSM) of thermally-sprayed Diamalloy 2002 coating

    NASA Astrophysics Data System (ADS)

    Gisario, A.; Barletta, M.; Veniali, F.

    2012-09-01

    Thermally-sprayed Diamalloy 2002 is widely used as overlay coating in several applications for their good wear and corrosion protection. Although, in the past, any effort has been produced to deposit Diamalloy 2002 with a low degree of defectiveness, some residual porosity and cracks can often affect the final property of the resulting coatings. Different techniques are commonly used to improve the performance of Diamalloy 2002. Recently, laser post-treatment seems to be one of the most promising, being an effective, non-contact, mini-invasive technology. In this respect, the present investigation deals with the application of a continuous wave high power diode laser to post-treat Diamalloy 2002 deposited by HVOF on AA 6082 T6 aluminum alloy. Different laser power and scan speed were investigated in order to identify the process window most favorable to improve the overall mechanical property of Diamalloy 2002 coatings. The changes in morphology, micro-structure and chemical composition of the coatings after laser post-treatments were investigated by inductive gage profilometry and combined SEM-EDXS. Further, the changes in the mechanical properties of the coatings were investigated in terms of hardness, elastic modulus, scratch and wear resistance. Consistent improvements in mechanical property can be achieved by Diamalloy 2002 when laser processing is performed at higher power and reduced scan speed. Yet, too much increase in power density should be always avoided as it can be detrimental to the final property of the coatings and cause high defectiveness and their failure.

  8. Flame spraying of polymers

    SciTech Connect

    Varacalle, D.J. Jr.; Zeek, D.P.; Couch, K.W.; Benson, D.M.; Kirk, S.M.

    1997-08-01

    Statistical design-of-experiment studies of the thermal spraying of polymer powders are presented. Studies of the subsonic combustion (i.e., Flame) process were conducted in order to determine the quality and economics of polyester and urethane coatings. Thermally sprayed polymer coatings are of interest to several industries for anticorrosion applications, including the chemical, automotive, and aircraft industries. In this study, the coating design has been optimized for a site-specific application using Taguchi-type fractional-factorial experiments. Optimized coating designs are presented for the two powder systems. A substantial range of thermal processing conditions and their effect on the resultant polymer coatings is presented. The coatings were characterized by optical metallography, hardness testing, tensile testing, and compositional analysis. Characterization of the coatings yielded the thickness, bond strength, Knoop microhardness, roughness, deposition efficiency, and porosity. Confirmation testing was accomplished to verify the coating designs.

  9. Microstructure and deformation behavior of nickel based superalloy Inconel 740 prepared by electron beam smelting

    SciTech Connect

    Tan, Yi You, Xiaogang; You, Qifan; Li, Jiayan; Shi, Shuang; Li, Pengting

    2016-04-15

    Electron beam smelting (EBS) has been used to fabricate the Inconel 740 superalloy. Microstructures, hardness, and deformation characteristics of the alloy are studied. It is observed that carbides and fine secondary phase nuclei are distributed in the hot worked EBS 740 superalloy. The Ostwald ripening occurs during solution treatment and leads to aggregation of the γ′ precipitates, the size of γ′ precipitates varies from several nanometers to more than one hundred nanometers as a result. The average size of the secondary phase is < 30 nm after aging treatment and the average Vickers hardness is measured to be about 370. The critical shear stress is calculated to be 0.627 GPa with governing mechanism of shearing, causing a stronger strengthening effect than the traditionally prepared Inconel 740 superalloy. The compression behavior indicates that the EBS 740 superalloy shows higher flow stress than 740H at low Zener-Hollomon parameter, which may arise from the undissolved γ′ precipitates and higher activation energy Q. The tensile results show that the fracture surface exhibits a ductile fracture pattern, in contrast to no obvious plastic deformation on the macroscopic fracture. Crack propagation proceeds in a transgranular fracture mode with facets and voids presented on the fracture surface. - Graphical abstract: Electron beam smelting (EBS) has been used to fabricate the Inconel 740 superalloy. Microstructures, hardness, and deformation characteristics of the alloy are studied. The average size of the secondary phase is < 30 nm after aging treatment and the average Vickers hardness is measured to be about 370. The critical shear stress is calculated to be 0.627 GPa with governing mechanism of shearing, causing a stronger strengthening effect than the traditionally prepared Inconel 740 superalloy. The EBS 740 superalloy shows higher flow stress than 740H at low Zener-Hollomon parameter, which may arise from the undissolved γ′ precipitates and higher

  10. Additive manufacturing of Inconel 718 using electron beam melting: Processing, post-processing, & mechanical properties

    NASA Astrophysics Data System (ADS)

    Sames, William James, V.

    Additive Manufacturing (AM) process parameters were studied for production of the high temperature alloy Inconel 718 using Electron Beam Melting (EBM) to better understand the relationship between processing, microstructure, and mechanical properties. Processing parameters were analyzed for impact on process time, process temperature, and the amount of applied energy. The applied electron beam energy was shown to be integral to the formation of swelling defects. Standard features in the microstructure were identified, including previously unidentified solidification features such as shrinkage porosity and non-equilibrium phases. The as-solidified structure does not persist in the bulk of EBM parts due to a high process hold temperature (˜1000°C), which causes in situ homogenization. The most significant variability in as-fabricated microstructure is the formation of intragranular delta-phase needles, which can form in samples produced with lower process temperatures (< 960°C). A novel approach was developed and demonstrated for controlling the temperature of cool down, thus providing a technique for in situ heat treatment of material. This technique was used to produce material with hardness of 478+/-7 HV with no post-processing, which exceeds the hardness of peak-aged Inconel 718. Traditional post-processing methods of hot isostatic pressing (HIP) and solution treatment and aging (STA) were found to result in variability in grain growth and phase solution. Recrystallization and grain structure are identified as possible mechanisms to promote grain growth. These results led to the conclusion that the first step in thermal post-processing of EBM Inconel 718 should be an optimized solution treatment to reset phase variation in the as-fabricated microstructure without incurring significant grain growth. Such an optimized solution treatment was developed (1120°C, 2hr) for application prior to aging or HIP. The majority of as-fabricated tensile properties met ASTM

  11. Spray Nozzle Calibrations

    DTIC Science & Technology

    1986-01-01

    1984. The manuscript was submitted for publication on October 2, 1985. AEOC-TR-85-eO CONTENTS Page J.O INTRODUCTION 1.1 General 5 1.2...1.1 GENERAL The formation of ice on aircraft surfaces occurs during flight through clouds of supercooled water droplets. Ice accretion on these... wind tunnel. Both the LWC and mean effective droplet size are set and maintained through variations in the water and air supply pressures of the spray

  12. Spray combustion stability project

    NASA Technical Reports Server (NTRS)

    Jeng, San-Mou; Litchford, Ron J.

    1990-01-01

    This report summarizes research activity on the Spray Combustion Stability Project, characterizes accomplishments and current status, and discusses projected future work. The purpose is to provide a concise conceptual overview of the research effort so the reader can quickly assimilate the gist of the research results and place them within the context of their potential impact on liquid rocket engine design technology. Therefore, this report does not elaborate on many of the detailed technical aspects of the research program.

  13. Vacuum plasma spray coating

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Mckechnie, Timothy N.

    1989-01-01

    Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

  14. OXIDATION OF INCONEL 718 IN AIR AT TEMPERATURES FROM 973K TO 1620K.

    SciTech Connect

    GREENE,G.A.; FINFROCK,C.C.

    2000-10-01

    As part of the APT project, it was necessary to quantify the release of tungsten from the APT spallation target during postulated accident conditions in order to develop accident source terms for accident consequence characterization. Experiments with tungsten rods at high temperatures in a flowing steam environment characteristic of postulated accidents revealed that considerable vaporization of the tungsten occurred as a result of reactions with the steam and that the aerosols which formed were readily transported away from the tungsten surfaces, thus exposing fresh tungsten to react with more steam. The resulting tungsten release fractions and source terms were undesirable and it was decided to clad the tungsten target with Inconel 718 in order to protect it from contact with steam during an accident and mitigate the accident source term and the consequences. As part of the material selection criteria, experiments were conducted with Inconel 718 at high temperatures to evaluate the rate of oxidation of the proposed clad material over as wide a temperature range as possible, as well as to determine the high-temperature failure limit of the material. Samples of Inconel 718 were inserted into a preheated furnace at temperatures ranging from 973 K to 1620 K and oxidized in air for varying periods of time. After oxidizing in air at a constant temperature for the prescribed time and then being allowed to cool, the samples would be reweighed to determine their weight gain due to the uptake of oxygen. From these weight gain measurements, it was possible to identify three regimes of oxidation for Inconel 718: a low-temperature regime in which the samples became passivated after the initial oxidation, an intermediate-temperature regime in which the rate of oxidation was limited by diffusion and exhibited a constant parabolic rate dependence, and a high-temperature regime in which material deformation and damage accompanied an accelerated oxidation rate above the parabolic

  15. Optimizing NiCr and FeCr HVOF Coating Structures for High Temperature Corrosion Protection Applications

    NASA Astrophysics Data System (ADS)

    Oksa, M.; Metsäjoki, J.

    2015-02-01

    In order to achieve a desired dense structure for coatings employed in high temperature corrosion conditions, thermal spray process optimization with diagnostic tools can be applied. In this study, NiCr (51Ni-46Cr-2Si-1Fe) and FeCr (Fe-19Cr-9W-7Nb-4Mo-5B-2C-2Si-1Mn) powders were sprayed with HVOFGF (gas-fueled) and HVOFLF (liquid-fueled) systems, and the spray processes were monitored with diagnostic tools, including SprayWatch for measuring the temperature and velocity of the spray stream, and in situ coating property (ICP measurement) for measuring the stress state. Various spray parameters were applied to attain the best coating characteristics for high temperature applications. Selected coatings were exposed to high temperature corrosion conditions both in laboratory and actual power plant. The coatings were analyzed by microscopic means and mechanical testing. The application of process-structure-properties-performance methodology with the process monitoring, analysis of the coating characteristics, and results of corrosion performance are presented in this paper.

  16. Fundamental studies of spray combustion

    SciTech Connect

    Li, S.C.; Libby, P.A.; Williams, F.A.

    1997-12-31

    Our research on spray combustion involves both experiment and theory and addresses the characteristics of individual droplets and of sprays in a variety of flows: laminar and turbulent, opposed and impinging. Currently our focus concerns water and fuel sprays in two stage laminar flames, i.e., flames arising, for example from a stream of fuel and oxidizer flowing opposite to an air stream carrying a water spray. Our interest in these flames is motivated by the goals of reducing pollutant emissions and extending the range of stable spray combustion. There remains considerable research to be carried out in order to achieve these goals. Thus far our research on the characteristics of sprays in turbulent flows has been limited to nonreacting jets impinging on a plate but this work will be extended to opposed flows with and without a flame. In the following we discuss details of these studies and our plans for future work.

  17. Closed loop spray cooling apparatus

    NASA Technical Reports Server (NTRS)

    Alger, D. L.; Schwab, W. B.; Furman, E. R. (Inventor)

    1979-01-01

    A closed loop apparatus for jet spraying coolant against the back of a radiation target is described. The coolant is circulated through a closed loop with a bubble of inert gas being maintained around the spray. Mesh material is disposed between the bubble and the surface of the liquid coolant which is below the bubble at a predetermined level. In a second arrangement no inert gas is used, the bubble consists of vapor produced when the coolant is sprayed against the target.

  18. 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.

  19. Photomicrographic Studies of Fuel Sprays

    NASA Technical Reports Server (NTRS)

    Lee, Dana W; Spencer, Robert C

    1934-01-01

    A large number of photomicrographs of fuel sprays were taken for the purpose of studying the spray structure and the process of spray formation. They were taken at magnifying powers of 2.5, 3.25, and 10, using a spark discharge of very short duration for illumination. Several types and sizes of nozzles were investigated, different liquids were used, and a wide range of injection pressures was employed. The sprays were photographed as they were injected into a glass-walled chamber in which the air density was varied from 14 atmospheres to 0.0013 atmosphere.

  20. Vacuum Plasma Spraying Replaces Electrodeposition

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

    1992-01-01

    Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

  1. Mechanical properties of Inconel 718 and Nickel 201 alloys after thermal histories simulating brazing and high temperature service

    NASA Technical Reports Server (NTRS)

    James, W. F.

    1985-01-01

    An experimental investigation was made to evaluate two nickel base alloys (Nickel-201 and Inconel-718) in three heat treated conditions. These conditions were: (1) annealed; (2) after thermal exposure simulating a braze cycle; and (3) after a thermal exposure simulating a braze cycle plus one operational lifetime of high temperature service. For the Nickel-201, two different braze cycle temperatures were evaluated. A braze cycle utilizing a lower braze temperature resulted in less grain growth for Nickel-201 than the standard braze cycle used for joining Nickel-201 to Inconel-718. It was determined, however, that Nickel-201, was marginal for temperatures investigated due to large grain growth. After the thermal exposures described above, the mechanical properties of Nickel-201 were degraded, whereas similar exposure on Inconel-718 actually strengthened the material compared with the annealed condition. The investigation included tensile tests at both room temperature and elevated temperatures, stress-rupture tests, and metallographic examination.

  2. Creep-Fatigue Cracking Near the Welded Interface in Friction Welding Dissimilar Superalloys INCONEL 718 and MAR-M247

    NASA Astrophysics Data System (ADS)

    Tra, Tran Hung; Okazaki, Masakazu

    2017-08-01

    A forged INCONEL 718 and a cast MAR-M247 alloy were joined by a friction welding process. The creep-fatigue strength of this joint was investigated. The life of the joint was significantly shorter than that of the base alloys. The joint failed near the interface of the INCONEL 718 side, although the life of INCONEL 718 was longer than that of MAR-M247. To understand this behavior, the stress field in the welding was numerically analyzed using a visco-elastic model. The results suggested that triaxiality in the stress state could be promoted near the welded interface and lead to an acceleration of creep-fatigue crack nucleation.

  3. Reaction of Inconel 690 and 693 in Iron Phosphate Melts: Alternative Glasses for Waste Vitrification

    SciTech Connect

    Day, Delbert E. Kim, Cheol-Woon

    2005-09-13

    The corrosion resistance of candidate materials used for the electrodes (Inconel 690 & 693) and the melt contact refractory (Monofrax K-3) in a Joule Heated Melter (JHM) has been investigated at the University of Missouri-Rolla (UMR) during the period from June 1, 2004 to August 31, 2005. This work was supported by the U.S. Department of Energy (DOE) Office of Biological and Environmental Research (DE-FG02-04ER63831). The unusual properties and characteristics of iron phosphate glasses, as viewed from the standpoint of alternative glasses for vitrifying nuclear and hazardous wastes which contain components that make them poorly suited for vitrification in borosilicate glass, were recently discovered at UMR. The expanding national and international interest in iron phosphate glasses for waste vitrification stems from their rapid melting and chemical homogenization which results in higher furnace output, their high waste loading that varies from 32 wt% up to 75 wt% for the Hanford LAW and HLW, respectively, and the outstanding chemical durability of the iron phosphate wasteforms which meets all present DOE requirements (PCT and VHT). The higher waste loading in iron phosphate glasses, compared to the baseline borosilicate glass, can reduce the time and cost of vitrification considerably since a much smaller mass of glass will be produced, for example, about 43% less glass when the LAW at Hanford is vitrified in an iron phosphate glass according to PNNL estimates. In view of the promising performance of iron phosphate glasses, information is needed for how to best melt these glasses on the scale needed for practical use. Melting iron phosphate glasses in a JHM is considered the preferred method at this time because its design could be nearly identical to the JHM now used to melt borosilicate glasses at the Defense Waste Processing Facility (DWPF), Westinghouse Savannah River Co. Therefore, it is important to have information for the corrosion of candidate electrode

  4. Spray algorithm without interface construction

    NASA Astrophysics Data System (ADS)

    Al-Kadhem Majhool, Ahmed Abed; Watkins, A. P.

    2012-05-01

    This research is aimed to create a new and robust family of convective schemes to capture the interface between the dispersed and the carrier phases in a spray without the need to build up the interface boundary. The selection of the Weighted Average Flux (WAF) scheme is due to this scheme being designed to deal with random flux scheme which is second-order accurate in space and time. The convective flux in each cell face utilizes the WAF scheme blended with Switching Technique for Advection and Capturing of Surfaces (STACS) scheme for high resolution flux limiters. In the next step, the high resolution scheme is blended with the WAF scheme to provide the sharpness and boundedness of the interface by using switching strategy. In this work, the Eulerian-Eulerian framework of non-reactive turbulent spray is set in terms of theoretical proposed methodology namely spray moments of drop size distribution, presented by Beck and Watkins [1]. The computational spray model avoids the need to segregate the local droplet number distribution into parcels of identical droplets. The proposed scheme is tested on capturing the spray edges in modelling hollow cone sprays without need to reconstruct two-phase interface. A test is made on simple comparison between TVD scheme and WAF scheme using the same flux limiter on convective flow hollow cone spray. Results show the WAF scheme gives a better prediction than TVD scheme. The only way to check the accuracy of the presented models is by evaluating the spray sheet thickness.

  5. A New Way to Spray

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A NASA SBIR contract provided the funding for a new nozzle shape to be used in plasma spray techniques. The new design, a bell shape, reduces overspray. The result is a significant decrease in the cost of plasma spraying and a higher quality, more pure coating.

  6. Mechanical behavior of post-processed Inconel 718 manufactured through the electron beam melting process

    SciTech Connect

    Kirka, Michael M.; Medina, Frank; Dehoff, Ryan R.; Okello, Alfred O.

    2016-10-21

    Here, the electron beam melting (EBM) process was used to fabricate Inconel 718. The microstructure and tensile properties were characterized in both the as-fabricated and post-processed state transverse (T-orientation) and longitudinal (L-orientation) to the build direction. Post-processing involved both a hot isostatic pressing (HIP) and solution treatment and aging (STA) to homogenize the microstructure. In the as-fabricated state, EBM Inconel 718 exhibits a spatially dependent microstructure that is a function of build height. Spanning the last few layers is a cored dendritic structure comprised of the products (carbides and Laves phase) predicted under equilibrium solidification conditions. With increasing distance from the build's top surface, the cored dendritic structure becomes increasingly homogeneous with complete dissolution of the secondary dendrite arms. Further, temporal phase kinetics are observed to lead to the dissolution of the strengthening γ"γ" and precipitation of networks of fine δ needles that span the grains. Microstructurally, post-processing resulted in dissolution of the δ networks and homogeneous precipitation of γ'"γ'" throughout the height of the build. In the as-fabricated state, the monotonic tensile behavior exhibits a height sensitivity within the T-orientation at both 20 and 650 °C. Along the L-orientation, the tensile behavior exhibits strength values comparable to the reference wrought material in the fully heat-treated state. After post-processing, the yield strength, ultimate strength, and elongation at failure for the EBM Inconel 718 were observed to have beneficially increased compared to the as-fabricated material. Further, as a result of post-processing the spatial variance of the ultimate yield strength and elongation at failure within the transverse direction decreased by 4 and 3× respectively.

  7. Mechanical behavior of post-processed Inconel 718 manufactured through the electron beam melting process

    DOE PAGES

    Kirka, Michael M.; Medina, Frank; Dehoff, Ryan R.; ...

    2016-10-21

    Here, the electron beam melting (EBM) process was used to fabricate Inconel 718. The microstructure and tensile properties were characterized in both the as-fabricated and post-processed state transverse (T-orientation) and longitudinal (L-orientation) to the build direction. Post-processing involved both a hot isostatic pressing (HIP) and solution treatment and aging (STA) to homogenize the microstructure. In the as-fabricated state, EBM Inconel 718 exhibits a spatially dependent microstructure that is a function of build height. Spanning the last few layers is a cored dendritic structure comprised of the products (carbides and Laves phase) predicted under equilibrium solidification conditions. With increasing distance frommore » the build's top surface, the cored dendritic structure becomes increasingly homogeneous with complete dissolution of the secondary dendrite arms. Further, temporal phase kinetics are observed to lead to the dissolution of the strengthening γ"γ" and precipitation of networks of fine δ needles that span the grains. Microstructurally, post-processing resulted in dissolution of the δ networks and homogeneous precipitation of γ'"γ'" throughout the height of the build. In the as-fabricated state, the monotonic tensile behavior exhibits a height sensitivity within the T-orientation at both 20 and 650 °C. Along the L-orientation, the tensile behavior exhibits strength values comparable to the reference wrought material in the fully heat-treated state. After post-processing, the yield strength, ultimate strength, and elongation at failure for the EBM Inconel 718 were observed to have beneficially increased compared to the as-fabricated material. Further, as a result of post-processing the spatial variance of the ultimate yield strength and elongation at failure within the transverse direction decreased by 4 and 3× respectively.« less

  8. Industrial Process Design for Manufacturing Inconel 718 Extremely Large Forged Rings

    NASA Astrophysics Data System (ADS)

    Ambielli, John F.

    2011-12-01

    Inconel 718 is a Ni-Fe-based superalloy that has been central to the gas turbine industry since its discovery in 1963. While much more difficult to process than carbon or stainless steels, among its superalloy peers Inconel 718 has relatively high forgeability and has been used to make discs, rings, shells, and structural components. A metal forming process design algorithm is presented to incorporate key criteria relevant to superalloy processing. This algorithm was applied to conceptual forging and heat treating extremely large rings of Inconel 718 of diameter 1956 mm (77in) and weight 3252 kg (7155 lb). A 3-stage standard thermomechanical (TMP) processing was used, where Stage 1 strain varied from 0.1190 to 0.2941, Stage 2 from 0.0208 to 0.0357 and Stage 3 from 0.0440 to 0.0940. This was followed by heat treatment of a solution anneal (954°C/1750°F for 4 hour hold), air cool, then a double aging (718°C/1325°F for 8 hour hold; furnace cool to 621°C/1150°F 56°C/100°F per hr; 18 hour total time for both steps). Preliminary mechanical testing was performed. Average yield strength of 951 MPa/138 ksi (longitudinal) and 979 MPa/142 ksi (axial) was achieved. Tensile strengths were 1276 MPa/185 ksi (longitudinal) and 1255 MPa/182 ksi (axial). Elongations and reduction of areas attained were, respectively, 18 (long) and 25 (axial) and 28 (long) and 27 (axial).

  9. Microstructures and microhardness at fusion boundary of 316 stainless steel/Inconel 182 dissimilar welding

    SciTech Connect

    Wang, Wei; Lu, Yonghao; Ding, Xianfei; Shoji, Tetsuo

    2015-09-15

    Microstructures and microhardness at fusion boundary of a weld joint were investigated in a 316 stainless steel/Inconel 182 dissimilar weldment. The results showed that there were two alternately distributed typical fusion boundaries, a narrow random boundary (possessed 15% in length) with a clear sharp interface and an epitaxial fusion one with (100){sub BM}//(100){sub WM} at the joint interface. The composition transition, microstructure and hardness across the fusion boundary strongly depended on the type of the fusion boundary. For the random boundary, there was a clear sharp interface and the composition transition with a width of 100 μm took place symmetrically across the grain boundary. For the epitaxial fusion one, however, there were Type-I and Type-II grain boundaries perpendicular and parallel to the epitaxial fusion boundary, respectively. The composition transition took place in the Inconel 182 weld side. Σ3 boundaries in the HAZ of 316SS side and Σ5 grain boundaries in weld metal were usually observed, despite the type of fusion boundary, however the former was much more in epitaxial fusion boundary. Microhardness was continuously decreased across the random fusion boundary from the side of Inconel 182 to 316SS, but a hardening phenomenon appeared in the epitaxial fusion boundary zone because of its fine cellular microstructure. - Highlights: • Two typical fusion boundaries alternately distributed in the fusion interface • The microstructure, composition and hardness across fusion boundary depended on its type. • Different regions in welded joint have different special CSL value boundaries. • Hardening phenomenon only appeared in the epitaxial fusion boundary.

  10. A Comparison of Weld-Repaired and Base Metal for Inconel 718 and CRES 321 at Cryogenic and Room Temperatures

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Smith, Stephen W.; Willard, Scott A.; Piascik, Robert S.

    2004-01-01

    Fatigue crack growth tests were conducted to characterize the performance of Inconel 718 and CRES 321 welds, weld heat-affect-zone and parent metal at room temperature laboratory air and liquid nitrogen (-196oC) environments. The results of this study were required to predict the damage tolerance behavior of proposed orbiter main engine hydrogen fuel liner weld repairs. Experimental results show that the room and cryogenic temperature fatigue crack growth characteristics of both alloys are not significantly degraded by the weld repair process. However, both Inconel 718 and CRES 321 exhibited lower apparent toughness within the weld repair region compared to the parent metal.

  11. Substrate system for spray forming

    DOEpatents

    Chu, Men G.; Chernicoff, William P.

    2002-01-01

    A substrate system for receiving a deposit of sprayed metal droplets including a movable outer substrate on which the sprayed metal droplets are deposited. The substrate system also includes an inner substrate disposed adjacent the outer substrate where the sprayed metal droplets are deposited on the outer substrate. The inner substrate includes zones of differing thermal conductivity to resist substrate layer porosity and to resist formation of large grains and coarse constituent particles in a bulk layer of the metal droplets which have accumulated on the outer substrate. A spray forming apparatus and associated method of spray forming a molten metal to form a metal product using the substrate system of the invention is also provided.

  12. Substrate system for spray forming

    DOEpatents

    Chu, Men G.; Chernicoff, William P.

    2000-01-01

    A substrate system for receiving a deposit of sprayed metal droplets including a movable outer substrate on which the sprayed metal droplets are deposited. The substrate system also includes an inner substrate disposed adjacent the outer substrate where the sprayed metal droplets are deposited on the outer substrate. The inner substrate includes zones of differing thermal conductivity to resist substrate layer porosity and to resist formation of large grains and coarse constituent particles in a bulk layer of the metal droplets which have accumulated on the outer substrate. A spray forming apparatus and associated method of spray forming a molten metal to form a metal product using the substrate system of the invention is also provided.

  13. Prior deformation effects on creep and fracture in inconel alloy X-750

    NASA Astrophysics Data System (ADS)

    Pandey, M. C.; Mukherjee, A. K.; Taplin, D. M. R.

    1984-07-01

    Creep fracture process in Inconel alloy X-750 can be modified by room-temperature prestraining. It has been observed that fracture in the prestrained specimens occurred due to growth and interlinkage of the prenucleated voids whereas failure occurred by plastic instability in the non-prestrained specimens. Creep ductility and the times-to-rupture are found to decrease progressively with room-temperature prestraining, but there is no marked influence on the minimum creep rate. This is explained in terms of two compcting processes: a weakening effect caused by prenucleation of grain boundary voids and a hardening effect due to generation of dislocations due to the prestraining.

  14. Effect of Plasma Nitriding Parameters on the Wear Resistance of Alloy Inconel 718

    NASA Astrophysics Data System (ADS)

    Kovací, Halim; Ghahramanzadeh ASL, Hojjat; Albayrak, Çigdem; Alsaran, Akgün; Çelik, Ayhan

    2016-11-01

    The effect of the temperature and duration of plasma nitriding on the microstructure and friction and wear parameters of Inconel 718 nickel alloy is investigated. The process of plasma nitriding is conducted in a nitrogen-hydrogen gaseous mixture at a temperature of 400, 500 and 600°C for 1 and 4 h. The modulus of elasticity of the nitrided layer, the micro- and nanohardness, the surface roughness, the friction factor and the wear resistance of the alloy are determined prior to and after the nitriding. The optimum nitriding regime providing the best tribological characteristics is determined.

  15. Corrosion Resistance of Laser Clads of Inconel 625 and Metco 41C

    NASA Astrophysics Data System (ADS)

    Němeček, Stanislav; Fidler, Lukáš; Fišerová, Pavla

    The present paper explores the impact of laser cladding parameters on the corrosion behaviour of the resulting surface. Powders of Inconel 625 and austenitic Metco 41C steel were deposited on steel substrate. It was confirmed that the level of dilution has profound impact on the corrosion resistance and that dilution has to be minimized. However, the chemical composition of the cladding is altered even in the course of the cladding process, a fact which is related to the increase in the substrate temperature. The cladding process was optimized to achieve maximum corrosion resistance. The results were verified and validated using microscopic observation, chemical analysis and corrosion testing.

  16. Spectral Emittance of Uncoated and Ceramic-Coated Inconel and Type 321 Stainless Steel

    NASA Technical Reports Server (NTRS)

    Richmond, Joseph C.; Stewart, James E.

    1959-01-01

    The normal spectral emittance of Inconel and type 321 stainless steel with different surface treatments was measured at temperatures of 900, 1,200, 1,500, and 1,800 F over a wavelength range of 1.5 to 15 microns. The measurements involved comparison of the radiant energy emitted by the heated specimen with that emitted by a comparison standard at the same temperature by means of a recording double-beam infrared spectrophotometer. The silicon carbide comparison standard had previously been calibrated against a laboratory black-body furnace. Surface treatments included electropolishing, sandblasting, electro-polishing followed by oxidation in air for 1/2 hour at 1,800 F, sandblasting followed by oxidation in air for 1/2 hour at 1,800 F, application of National Bureau of Standards coating A-418, and application of NBS ceramic coating N-143. The normal spectral emittance of both alloys in the electropolished condition was low and decreased very slightly with increasing wavelength while in the sandblasted condition it was somewhat higher and did not vary appreciably with wavelength. The oxidation treatment greatly increased the normal spectral emittance of both the electropolished and sandblasted type 321 stainless steel specimens and of the electropolished Inconel specimens and introduced some spectral selectivity into the curves. The oxidation increased the normal spectral emittance of the sandblasted Inconel specimens only moderately. Of the specimens to which a coating about 0.002 inch thick was applied, those coated with A-418 had higher emittance at all wavelengths than did those coated with N-143, and the coated specimens of Inconel had higher spectral emittance at all wavelengths than did the corresponding specimens of type 321 stainless steel. Both coatings were found to be partially transparent to the emitted energy at this thickness but essentially opaque at a thickness of 0.005 inch. Coated specimens with 0.005 inch or more of coating did not show the effect

  17. Development of an inconel self powered neutron detector for in-core reactor monitoring

    NASA Astrophysics Data System (ADS)

    Alex, M.; Ghodgaonkar, M. D.

    2007-04-01

    The paper describes the development and testing of an Inconel600 (2 mm diameter×21 cm long) self-powered neutron detector for in-core neutron monitoring. The detector has 3.5 mm overall diameter and 22 cm length and is integrally coupled to a 12 m long mineral insulated cable. The performance of the detector was compared with cobalt and platinum detectors of similar dimensions. Gamma sensitivity measurements performed at the 60Co irradiation facility in 14 MR/h gamma field showed values of -4.4×10 -18 A/R/h/cm (-9.3×10 -24 A/ γ/cm 2-s/cm), -5.2×10 -18 A/R/h/cm (-1.133×10 -23 A/ γ/cm 2-s/cm) and 34×10 -18 A/R/h/cm (7.14×10 -23 A/ γ/cm 2-s/cm) for the Inconel, Co and Pt detectors, respectively. The detectors together with a miniature gamma ion chamber and fission chamber were tested in the in-core Apsara Swimming Pool type reactor. The ion chambers were used to estimate the neutron and gamma fields. With an effective neutron cross-section of 4b, the Inconel detector has a total sensitivity of 6×10 -23 A/nv/cm while the corresponding sensitivities for the platinum and cobalt detectors were 1.69×10 -22 and 2.64×10 -22 A/nv/cm. The linearity of the detector responses at power levels ranging from 100 to 200 kW was within ±5%. The response of the detectors to reactor scram showed that the prompt response of the Inconel detector was 0.95 while it was 0.7 and 0.95 for the platinum and cobalt self-powered detectors, respectively. The detector was also installed in the horizontal flux unit of 540 MW Pressurised Heavy Water Reactor (PHWR). The neutron flux at the detector location was calculated by Triveni code. The detector response was measured from 0.02% to 0.07% of full power and showed good correlation between power level and detector signals. Long-term tests and the dynamic response of the detector to shut down in PHWR are in progress.

  18. Crack-growth behavior in thick welded plates of Inconel 718 at room and cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Forman, R. G.

    1974-01-01

    Results of mechanical-properties and axial-load fatigue and fracture tests performed on thick welded plates of Inconel 718 superalloy are presented. The test objectives were to determine the tensile strength properties and the crack-growth behavior in electron-beam, plasma-arc, and gas tungsten are welds for plates 1.90 cm (0.75 in) thick. Base-metal specimens were also tested to determine the flaw-growth behavior. The tests were performed in room-temperature-air and liquid nitrogen environments. The experimental crack-growth-rate data are correlated with theoretical crack-growth-rate predictions for semielliptical surface flaws.

  19. Comparative Study of Microstructure and Properties of Thermal Sprayed MCrAlY Bond Coatings

    NASA Astrophysics Data System (ADS)

    Inglima, Michael William

    A series of experiments were performed in order to observe certain process-property trends in thermally sprayed MCrAlY bond coatings for thermal barrier coating (TBC) applications in gas-turbine engines. Firstly, the basis of gas-turbine operation and design is discussed with a focus on the Brayton cycle and basic thermodynamic properties with respect to both the thermal and fuel efficiency of the turbine. The high-temperature environment inside the gas-turbine engine creates an extremely corrosive medium in which the engineering components must operate with sufficient operating life times. These engineering constraints, both thermal/fuel efficiency and operating life, pose a serious problem during long operation as well as thermal cycling of a civil aerospace engine. The concept of a thermal barrier coating is introduced along with how these coatings protect the internal engineering components, mostly in the hot-section of the turbine, and increase both the efficiency as well as the operating life of the components. The method used to create TBC's is then introduced being thermal spray processing along with standard operating procedures (SOP) used during coating deposition. The main focus of the experiments was to quantify the process-property trends seen during thermal spray processing of TBC's with respect to the adhesion and thermally grown oxide (TGO) layer, as well as how sensitive these properties are to changing variables during coating deposition. The design of experiment (DOE) method was used in order to have sufficient statistical process control over the output as well as a standard method for quantifying the results. A total of three DOE's were performed using two main types of thermal spray processes being high-velocity oxygen fuel (HVOF) and atmospheric plasma spray (APS), with a total of five different types of torches which are categorized by liquid-fuel, gas-fuel, and single cathode plasma. The variables used in the proceeding experiments were

  20. INEL Spray-forming Research

    NASA Technical Reports Server (NTRS)

    Mchugh, Kevin M.; Key, James F.

    1993-01-01

    Spray forming is a near-net-shape fabrication technology in which a spray of finely atomized liquid droplets is deposited onto a suitably shaped substrate or mold to produce a coherent solid. The technology offers unique opportunities for simplifying materials processing without sacrificing, and oftentimes substantially improving, product quality. Spray forming can be performed with a wide range of metals and nonmetals, and offers property improvements resulting from rapid solidification (e.g., refined microstructures, extended solid solubilities and reduced segregation). Economic benefits result from process simplification and the elimination of unit operations. Researchers at the Idaho National Engineering Laboratory (INEL) are developing spray-forming technology for producing near-net-shape solids and coatings of a variety of metals, polymers, and composite materials. Results from several spray forming programs are presented to illustrate the range of capabilities of the technique as well as the accompanying technical and economic benefits. Low-carbon steel strip greater than 0.75 mm thick and polymer membranes for gas/gas and liquid/liquid separations that were spray formed are discussed; recent advances in spray forming molds, dies, and other tooling using low-melting-point metals are described.

  1. INEL spray-forming research

    SciTech Connect

    McHugh, K.M.; Key, J.F.

    1992-01-01

    Spray forming is a near-net-shape fabrication technology in which a spray of finely atomized liquid droplets is deposited onto a suitably shaped substrate or mold to produce a coherent solid. The technology offers unique opportunities for simplifying materials processing without sacrificing, and oftentimes substantially improving, product quality. Spray forming can be performed with a wide range of metals and nonmetals, and offers property improvements resulting from rapid solidification (e.g. refined microstructures, extended solid solubilities and reduced segregation). Economic benefits result from process simplification and the elimination of unit operations. Researchers at the Idaho National Engineering Laboratory (INEL) are developing spray-forming technology for producing near-net-shape solids and coatings of a variety of metals, polymers, and composite materials. Results from several spray-forming programs are presented to illustrate the range of capabilities of the technique as well as the accompanying technical and economic benefits. Low-carbon steel strip >0.75 mm thick and polymer membranes for gas/gas and liquid/liquid separations that were spray formed are discussed; recent advances in spray forming molds, dies, and other tooling using low-melting-point metals are described.

  2. A fluorescent tracer method for evaluating spray transport and fate of field and laboratory spray applications

    USDA-ARS?s Scientific Manuscript database

    Field and laboratory testing spray nozzles and application systems use spray collectors to assess where the spray deposits once it leaves the spray system. Tracer materials, such as oil and water soluble fluorescent dyes, can be mixed into spray solutions in small amounts with minimal impact on the...

  3. Cold Spray Technology for DOD Applications

    DTIC Science & Technology

    2012-08-01

    Distribution Unlimited Mechanical Mixing at Interface • .. Sm-in ,, aluminum Approved for Public Release; Distribution Unlimited Cold Spray vs...of Corrosion Damage on Fielded Parts and Subsequent to Cold Spray Repair Before After 15 Cold Spray HP- Aluminum Fill...Unlimited Development and Implementation of Commercially Pure (CP) Aluminum and 6061 Aluminum Alloy Cold Spray Coatings for the Repair of Magnesium

  4. Influence of the Substrate on the Formation of Metallic Glass Coatings by Cold Gas Spraying

    NASA Astrophysics Data System (ADS)

    Henao, John; Concustell, Amadeu; Dosta, Sergi; Cinca, Núria; Cano, Irene G.; Guilemany, Josep M.

    2016-06-01

    Cold gas spray technology has been used to build up coatings of Fe-base metallic glass onto different metallic substrates. In this work, the effect of the substrate properties on the viscoplastic response of metallic glass particles during their impact has been studied. Thick coatings with high deposition efficiencies have been built-up in conditions of homogeneous flow on substrates such as Mild Steel AISI 1040, Stainless Steel 316L, Inconel 625, Aluminum 7075-T6, and Copper (99.9%). Properties of the substrate have been identified to play an important role in the viscoplastic response of the metallic glass particles at impact. Depending on the process gas conditions, the impact morphologies show not only inhomogeneous deformation but also homogeneous plastic flow despite the high strain rates, 108 to 109 s-1, involved in the technique. Interestingly, homogenous deformation of metallic glass particles is promoted depending on the hardness and the thermal diffusivity of the substrate and it is not exclusively a function of the kinetic energy and the temperature of the particle at impact. Coating formation is discussed in terms of fundamentals of dynamics of undercooled liquids, viscoplastic flow mechanisms of metallic glasses, and substrate properties. The findings presented in this work have been used to build up a detailed scheme of the deposition mechanism of metallic glass coatings by the cold gas spraying technology.

  5. Control of the kerf size and microstructure in Inconel 738 superalloy by femtosecond laser beam cutting

    NASA Astrophysics Data System (ADS)

    Wei, J.; Ye, Y.; Sun, Z.; Liu, L.; Zou, G.

    2016-05-01

    Femtosecond laser beam cutting is becoming widely used to meet demands for increasing accuracy in micro-machining. In this paper, the effects of processing parameters in femtosecond laser beam cutting on the kerf size and microstructure in Inconel 738 have been investigated. The defocus, pulse width and scanning speed were selected to study the controllability of the cutting process. Adjusting and matching the processing parameters was a basic enhancement method to acquire well defined kerf size and the high-quality ablation of microstructures, which has contributed to the intensity clamping effect. The morphology and chemical compositions of these microstructures on the cut surface have been characterized by a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Additionally, the material removal mechanism and oxidation mechanism on the Inconel 738 cut surface have also been discussed on the basis of the femtosecond laser induced normal vaporization or phase explosion, and trapping effect of the dangling bonds.

  6. Microstructure and micro-texture evolution during large strain deformation of Inconel alloy IN718

    SciTech Connect

    Nayan, Niraj; Gurao, N.P.; Narayana Murty, S.V.S.; Jha, Abhay K.; Pant, Bhanu; George, Koshy M.

    2015-12-15

    The hot deformation behaviour of Inconel alloy IN718 was studied in the temperature range of 950–1100 °C and at strain rates of 0.01 and 1 s{sup −1} with a view to understand the microstructural evolution as a function of strain rate and temperature. For this purpose, a single hit, hot isothermal plane strain compression (PSC) technique was used. The flow curves obtained during PSC exhibited weak flow softening at higher temperatures. Electron backscattered diffraction analysis (EBSD) of the PSC tested samples at the location of maximum strain revealed dynamic recrystallisation occurring at higher temperatures. Based on detailed microstructure and microtexture analyses, it was concluded that single step, large strain deformation has a distinct advantage in the thermo-mechanical processing of Inconel alloy IN718. - Highlights: • Plane strain compression (PSC) on IN718 was conducted. • Evolution of microstructure during large strain deformation was studied. • Flow curves exhibited weak softening at higher temperatures and dipping of the flow curve at a strain rate of 1 s{sup −1}. • Optimization of microstructure and process parameter for hot rolling possible by plane strain compression testing • Dynamic recrystallisation occurs in specimens deformed at higher temperatures and lower strain rates.

  7. Experimental Investigation Nano Particles Influence in NPMEDM to Machine Inconel 800 with Electrolyte Copper Electrode

    NASA Astrophysics Data System (ADS)

    Karunakaran, K.; Chandrasekaran, M.

    2017-05-01

    The recent technology of machining hard materials is Powder mix dielectric electrical Discharge Machining (PMEDM). This research investigates nano sized (about 5Nm) powders influence in machining Inconel 800 nickel based super alloy. This work is motivated for a practical need for a manufacturing industry, which processes various kinds of jobs of Inconel 800 material. The conventional EDM machining also considered for investigation for the measure of Nano powders performances. The aluminum, silicon and multi walled Carbon Nano tubes powders were considered in this investigation along with pulse on time, pulse of time and input current to analyze and optimize the responses of Material Removal Rate, Tool Wear Rate and surface roughness. The Taguchi general Full Factorial Design was used to design the experiments. The most advance equipments employed in conducting experiments and measuring equipments to improve the accuracy of the result. The MWCNT powder mix was out performs than other powders which reduce 22% to 50% of the tool wear rate, gives the surface roughness reduction from 29.62% to 41.64% and improved MRR 42.91% to 53.51% than conventional EDM.

  8. Relationship between ferromagnetic properties and grain size of Inconel alloy 600

    NASA Astrophysics Data System (ADS)

    Kikuchi, H.; Takahashi, H.; Yanagiwara, H.; Murakami, T.

    2015-05-01

    Inconel alloy 600 is widely used in steam generator tubings where sensitization due to chromium depletion occurs at grain boundaries and the sensitization induces tubing failures. Though the alloy usually exhibits paramagnetic properties, it shows ferromagnetic properties along grain boundaries when chromium depletion occurs. This means that magnetic nondestructive evaluation of sensitization is possible. Therefore, as a fundamental study to develop magnetic nondestructive evaluation technique for sensitization, the relationship between ferromagnetic properties and grain size in Inconel 600 was investigated using isothermal heat treatment. The grain was controlled using solution annealing, and then, specimens were heat treated at 873, 923, and 973 K within 400 h. The saturation magnetization increases as heat treatment time increases and eventually peaks. The peak time depends on the heat treatment temperature. The coercivity increases during the initial heat treatment stage, and decreases as the duration of heat treatment increases. The maximum saturation magnetization decreases as the grain diameter increases and is inversely proportional to the grain diameter squared, which is consistent with the fact that the ferromagnetic phase only formed along grain boundaries.

  9. Effect of Thermal Annealing on Machining-Induced Residual Stresses in Inconel 718

    NASA Astrophysics Data System (ADS)

    Madariaga, A.; Aperribay, J.; Arrazola, P. J.; Esnaola, J. A.; Hormaetxe, E.; Garay, A.; Ostolaza, K.

    2017-08-01

    Nickel-based alloys are widely employed in the manufacturing of aero-engines. These alloys are difficult to machine, and tensile residual stresses are generated during machining. These tensile residual stresses can negatively affect the performance of aero-engine components. Nevertheless, residual stresses can vary due to thermal or mechanical loading. These variations must be considered to evaluate the real influence of residual stresses on component behavior. This paper studies the effect of thermal loads on machining-induced residual stresses in the alloy Inconel 718. A ring-shaped Inconel 718 part was face-turned, and specimens were extracted from it. Specimens were exposed at 550 and 650 °C for 10 min, 1 and 10 h. Residual stresses were measured, and microstructure was observed before and after thermal exposure. Residual stress variations found after thermal exposure were the consequence of two factors: relaxation of strain bands during the early stage of exposure and diffusion-controlled creep. In addition, a modified Zener-Wert-Avrami model is proposed to predict residual stress relaxation caused by the diffusion-controlled creep. Once having fitted the modified Zener-Wert-Avrami model, the study was extended for a wider range of temperatures (400-650 °C). This analysis showed that surface residual stresses do not relax significantly at temperatures below 500 °C.

  10. Laser brazing of inconel 718 alloy with a silver based filler metal

    NASA Astrophysics Data System (ADS)

    Khorram, A.; Ghoreishi, M.; Torkamany, M. J.; Bali, M. M.

    2014-03-01

    In the presented study laser brazing of an inconel 718 alloy with silver based filler metal using 400 W pulsed Nd:YAG laser is investigated. Laser brazing was performed with varying laser frequency, pulse width, process speed and gap distance. The effect of preheating on wetting and spreading also was studied. Brazing geometrical images were observed using an optical microscope. The composition analysis and microstructure of the filler metal and brazed joints were examined using X-ray diffraction analyzer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Micro-hardness and tensile test were performed for investigation of mechanical properties. The experimental observations show that filler metal consist of α-Ag solid solution, ά-Cu solid solution surround by the α-Ag solid solution and eutectic structure. Phases of the brazed joint are similar to the filler metal. The results indicate that the filler metal has adequate wetting and spreading on inconel 718 and the wetting angle depends on the heat input significantly. Interdiffusion occurs in laser brazing and the average thickness of reaction layer is approximately 2.5 μm. Whenever the gap is big, it is needed to use longer pulse width in order to have a better melting flow. Preheating has significant influence on wetting and spreading of the filler metal.

  11. An experimental assessment on the performance of different lubrication techniques in grinding of Inconel 751.

    PubMed

    Balan, A S S; Vijayaraghavan, L; Krishnamurthy, R; Kuppan, P; Oyyaravelu, R

    2016-09-01

    The application of emulsion for combined heat extraction and lubrication requires continuous monitoring of the quality of emulsion to sustain a desired grinding environment; this is applicable to other grinding fluids as well. Thus to sustain a controlled grinding environment, it is necessary to adopt an effectively lubricated wheel-work interface. The current study was undertaken to assess experimentally the ​ effects of different grinding environments such as dry, minimum quantity lubrication (MQL) and Cryo-MQL on performance, such as grinding force, temperature, surface roughness and chip morphology on Inconel 751, a higher heat resistance material posing thermal problems and wheel loading. The results show that grinding with the combination of both liquid nitrogen (LN2) and MQL lowers temperature, cutting forces, and surface roughness as compared with MQL and dry grinding. Specific cutting energy is widely used as an inverse measure of process efficiency in machining. It is found from the results that specific cutting energy of Cryo-MQL assisted grinding is 50-65% lower than conventional dry grinding. The grindability of Inconel 751 superalloy can be enhanced with Cryo-MQL condition.

  12. Analysis of Deformation in Inconel 718 When the Stress Anomaly and Dynamic Strain Aging Coexist

    NASA Astrophysics Data System (ADS)

    Follansbee, Paul S.

    2016-09-01

    Deformation in Inconel 718 in the presence of combined effects of the stress anomaly and dynamic strain aging is analyzed according to an internal state variable model formulation. The analysis relies on the availability of experimental data in regimes of behavior where both the stress anomaly and dynamic strain aging are absent. A model that introduces two internal state variables—one characterizing interactions of dislocations with solute atoms and one characterizing interaction of dislocations with precipitates—is shown to adequately describe the temperature and strain-rate dependence of the yield stress in several superalloy systems. Strain hardening is then added with a third internal state variable to enable description of the full stress-strain curve. These equations are extrapolated into regimes where the stress anomaly and dynamic strain aging are present to identify signatures of their effects and to compare to similar analyses in a variety of metal systems. Dynamic strain aging in Inconel 718 follows similar trends to those observed previously. The magnitude of the stress anomaly tracks measurements of stress vs test temperature in pure Ni3Al. Several trends in the strain-rate sensitivity of elevated temperature deformation in superalloys are identified based on limited availability of measurements over a wide range of strain rates or tests using strain-rate changes.

  13. Surface Integrity and Structural Stability of Broached Inconel 718 at High Temperatures

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Peng, R. Lin; Moverare, J.; Avdovic, P.; Zhou, J. M.; Johansson, S.

    2016-07-01

    The current study focused on the surface integrity issues associated with broaching of Inconel 718 and the structural stability of the broached specimen at high temperatures, mainly involving the microstructural changes and residual stress relaxation. The broaching operation was performed using similar cutting conditions as that used in turbo machinery industries for machining fir-tree root fixings on turbine disks. Thermal exposure was conducted at 723 K, 823 K, and 923 K (450 °C, 550 °C, and 650 °C) for 30, 300, and 3000 hours, respectively. Surface cavities and debris dragging, sub-surface cracks, high intensity of plastic deformation, as well as the generation of tensile residual stresses were identified to be the main issues in surface integrity for the broached Inconel 718. When a subsequent heating was applied, surface recrystallization and α-Cr precipitation occurred beneath the broached surface depending on the applied temperature and exposure time. The plastic deformation induced by the broaching is responsible for these microstructural changes. The surface tension was completely relaxed in a short time at the temperature where surface recrystallization occurred. The tensile layer on the sub-surface, however, exhibited a much higher resistance to the stress relief annealing. Oxidation is inevitable at high temperatures. The study found that the surface recrystallization could promote the local Cr diffusion on the broached surface.

  14. Reduction of a thin chromium oxide film on Inconel surface upon treatment with hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Vesel, Alenka; Mozetic, Miran; Balat-Pichelin, Marianne

    2016-11-01

    Inconel samples with a surface oxide film composed of solely chromium oxide with a thickness of approximately 700 nm were exposed to low-pressure hydrogen plasma at elevated temperatures to determine the suitable parameters for reduction of the oxide film. The hydrogen pressure during treatment was set to 60 Pa. Plasma was created by a surfaguide microwave discharge in a quartz glass tube to allow for a high dissociation fraction of hydrogen molecules. Auger electron depth profiling (AES) was used to determine the decay of the oxygen in the surface film and X-ray diffraction (XRD) to measure structural modifications. During hydrogen plasma treatment, the oxidized Inconel samples were heated to elevated temperatures. The reduction of the oxide film started at temperatures of approximately 1300 K (considering the emissivity of 0.85) and the oxide was reduced in about 10 s of treatment as revealed by AES. The XRD showed sharper substrate peaks after the reduction. Samples treated in hydrogen atmosphere under the same conditions have not been reduced up to approximately 1500 K indicating usefulness of plasma treatment.

  15. Oxidation Behaviors of Inconel 740H in Air and Dynamic Steam

    NASA Astrophysics Data System (ADS)

    Lu, Jintao; Yang, Zhen; Xu, Songqian; Zhao, Haiping; Gu, Y.

    2016-08-01

    Inconel 740H alloy is a candidate material for 700°C advanced ultra-supercritical (A-USC) coal-fired power plants application as superheater/reheater tube. In this work, oxidation behavior of Inconel 740H alloy was studied in static air at 750°C and 850°C, and in dynamic pure steam at 750°C, respectively. The alloy was oxidized approximately following a parabolic law in three test environment. In the static air, the oxidation rate at 850°C was about 50 times of that at the 750°C. More NiCrMn spinal and TiO2 were detected after oxidation at 850°C. Cr2O3, however, was the main oxidation product at 750°C. In the pure steam, Cr2O3 was still the main oxidation product. The oxidation rate was about 2.6 times of that in static air, but the surface roughness was much smaller and edges of oxide particles were more blurred. There was no evidence of cracks or spallation in three test environments.

  16. Effect of Powder-Suspended Dielectric on the EDM Characteristics of Inconel 625

    NASA Astrophysics Data System (ADS)

    Talla, Gangadharudu; Gangopadhyay, S.; Biswas, C. K.

    2016-02-01

    The current work attempts to establish the criteria for powder material selection by investigating the influence of various powder-suspended dielectrics and machining parameters on various EDM characteristics of Inconel 625 (a nickel-based super alloy) which is nowadays regularly used in aerospace, chemical, and marine industries. The powders include aluminum (Al), graphite, and silicon (Si) that have significant variation in their thermo-physical characteristics. Results showed that powder properties like electrical conductivity, thermal conductivity, density, and hardness play a significant role in changing the machining performance and the quality of the machined surface. Among the three powders, highest material removal rate was observed for graphite powder due to its high electrical and thermal conductivities. Best surface finish and least radial overcut (ROC) were attained using Si powder. Maximum microhardness was found for Si due to its low thermal conductivity and high hardness. It is followed by graphite and aluminum powders. Addition of powder to the dielectric has increased the crater diameter due to expansion of plasma channel. Powder-mixed EDM (PMEDM) was also effective in lowering the density of surface cracks with least number of cracks obtained with graphite powder. X-ray diffraction analysis indicated possible formation of metal carbides along with grain growth phenomenon of Inconel 625 after PMEDM.

  17. Experimental Investigation into the Effect of Ball End Milling Parameters on Surface Integrity of Inconel 718

    NASA Astrophysics Data System (ADS)

    Bhopale, Nandkumar N.; Joshi, Suhas S.; Pawade, Raju S.

    2015-02-01

    In machining of Inconel 718, various difficulties such as increased tool wear and poor machined surface quality are frequently encountered due to its high temperature strength and poor thermal properties. This work considers the effect of number of passes and the machining environment on the machined surface quality in ball end milling of Inconel 718, which hitherto has not been adequately understood. To this effect, extensive experimentation has been carried out to analyze machined surface quality and integrity in terms of surface roughness, surface damage, and microhardness variation in the machined surfaces. The machined surfaces show formation of distinct bands as a function of instantaneous machining parameters along the periphery of cutting tool edge. A distinct variation is also observed in the measured values of surface roughness and microhardness in these regions. The minimum surface roughness is obtained in the stable cutting zone and it increases toward the periphery of the cutter on band #2 and band #3. Microhardness of depth beneath the machined surface shows that the machining affected zone varies from 60 to 100 µm in ball end milling under various machining conditions.

  18. Discontinuous Dynamic Recrystallization of Inconel 718 Superalloy During the Superplastic Deformation

    NASA Astrophysics Data System (ADS)

    Huang, Linjie; Qi, Feng; Hua, Peitao; Yu, Lianxu; Liu, Feng; Sun, Wenru; Hu, Zhuangqi

    2015-09-01

    The superplastic behavior of Inconel 718 superalloy with particular emphasis on the microstructural evolution has been systematically investigated through tensile tests at the strain rate of 10-3 s-1 and the temperatures ranging from 1223 K to 1253 K (950 °C to 980 °C). Its elongations exceeded 300 pct under all of the experimental conditions and peaked a maximum value of 520 pct at 1223 K (950 °C). Moreover, the stress reached the top value at the strain of 0.3, and then declined until the tensile failure. In addition, we have found that the grain size reduced after deformation while the δ phase precipitation increased. Microstructural evolution during the superplasticity was characterized via transmission electron microscope, and the randomly distributed dislocation, dislocation network, dislocation arrays, low-angled subgrains, and high-angled recrystallized new grains were observed in sequence. These new grains were found to nucleate at the triple junction, twin boundary, and near the δ phase. Based on these results, it is deemed that the discontinuous dynamic recrystallization occurred as the main mechanism for the superplastic deformation of Inconel 718 alloy.

  19. Laser post-processing of Inconel 625 made by selective laser melting

    NASA Astrophysics Data System (ADS)

    Witkin, David; Helvajian, Henry; Steffeney, Lee; Hansen, William

    2016-04-01

    The effect of laser remelting of surfaces of as-built Selective Laser Melted (SLM) Inconel 625 was evaluated for its potential to improve the surface roughness of SLM parts. Many alloys made by SLM have properties similar to their wrought counterparts, but surface roughness of SLM-made parts is much higher than found in standard machine shop operations. This has implications for mechanical properties of SLM materials, such as a large debit in fatigue properties, and in applications of SLM, where surface roughness can alter fluid flow characteristics. Because complexity and netshape fabrication are fundamental advantages of Additive Manufacturing (AM), post-processing by mechanical means to reduce surface roughness detracts from the potential utility of AM. Use of a laser to improve surface roughness by targeted remelting or annealing offers the possibility of in-situ surface polishing of AM surfaces- the same laser used to melt the powder could be amplitude modulated to smooth the part during the build. The effects of remelting the surfaces of SLM Inconel 625 were demonstrated using a CW fiber laser (IPG: 1064 nm, 2-50 W) that is amplitude modulated with a pulse profile to induce remelting without spallation or ablation. The process achieved uniform depth of melting and improved surface roughness. The results show that with an appropriate pulse profile that meters the heat-load, surface features such as partially sintered powder particles and surface connected porosity can be mitigated via a secondary remelting/annealing event.

  20. Gas Dynamic Spray Technology Demonstration

    NASA Technical Reports Server (NTRS)

    Burford, Pattie Lewis

    2011-01-01

    Zinc primer systems are currently used across NASA and AFSPC for corrosion protection of steel. AFSPC and NASA have approved the use of Thermal Spray Coatings (TSCs) as an environmentally preferable alternative. TSCs are approved in NASA-STD-5008 and AFSPC and KSC is currently looking for additional applications in which TSC can be used. Gas Dynamic Spray (GDS, also known as Cold Spray) is being evaluated as a means of repairing TSCs and for areas such as corners and edges where TSCs do not work as well. Other applications could include spot repair/maintenance of steel on structures, facilities, and ground support equipment.

  1. Plasma spraying with wire feedstock

    SciTech Connect

    Scholl, M.

    1994-12-31

    Plasma spraying has been limited to using powder feedstocks for a number of reasons. One limitation has been the low energy output of conventional plasma guns. The advent of high energy plasma spraying (HEPS) devices and the associated technology has effectively removed this functional limitation. With HEPS, the combination of high gas velocities and high thermal plasma temperatures coupled with a large exit gas volume enables wire and rod feedstocks to be effectively utilized. Rather than a bulk melting mechanism, a model based on ablation phenomena is considered. The paper examines an analysis of melting phenomena and presents a simple model for molten droplet formation for plasma spraying using wire feedstocks.

  2. Tensile Properties and Microstructure of Inconel 718 Fabricated with Electron Beam Freeform Fabrication (EBF(sup 3))

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Hibberd, Joshua

    2009-01-01

    Electron beam freeform fabrication (EBF3) direct metal deposition processing was used to fabricate two Inconel 718 single-bead-width wall builds and one multiple-bead-width block build. Specimens were machined to evaluate microstructure and room temperature tensile properties. The tensile strength and yield strength of the as-deposited material from the wall and block builds were greater than those for conventional Inconel 718 castings but were less than those for conventional cold-rolled sheet. Ductility levels for the EBF3 material were similar to those for conventionally-processed sheet and castings. An unexpected result was that the modulus of the EBF3-deposited Inconel 718 was significantly lower than that of the conventional material. This low modulus may be associated with a preferred crystallographic orientation resultant from the deposition and rapid solidification process. A heat treatment with a high solution treatment temperature resulted in a recrystallized microstructure and an increased modulus. However, the modulus was not increased to the level that is expected for Inconel 718.

  3. Microstructure and Properties of the Ti6Al4V/Inconel 625 Bimetal Obtained by Explosive Joining

    NASA Astrophysics Data System (ADS)

    Topolski, Krzysztof; Szulc, Zygmunt; Garbacz, Halina

    2016-08-01

    The study is concerned with the bimetallic plate composed of the Ti6Al4V and Inconel 625 alloys. The alloys were joined together using the explosive method with the aim to produce a bimetallic joint. The structure and the mechanical properties of the as-received raw Ti6Al4V and Inconel 625 alloys, the Ti6Al4V/Inconel 625 joint, and the joint after annealing (600 °C for 1 h) were examined. The samples observations were performed using a light microscope and a scanning electron microscope. The mechanical properties were estimated by microhardness measurements, tensile tests, and three-point bending tests. Moreover, the deformation strengthening of the metals and the strength of the joint were analyzed. The explosive process resulted in a good quality bimetallic joint. Both sheets were deformed plastically and the joint surface between the alloys had a wavy shape. In the area of the joint surface, the hardness was increased. For example, the annealing at 600 °C for 1 h resulted in changes of the microhardness in the entire volume of the samples and in changes of the morphology of the joint surface. In three-point bending tests, the samples were examined in two opposite positions (Ti6Al4V on the top or Inconel 625 on the top). The results indicated to depend on the position in which the sample was tested.

  4. Effect of service exposure on fatigue crack propagation of Inconel 718 turbine disc material at elevated temperatures

    SciTech Connect

    Jeong, Dae-Ho; Choi, Myung-Je; Goto, Masahiro; Lee, Hong-Chul; Kim, Sangshik

    2014-09-15

    In this study, the fatigue crack propagation behavior of Inconel 718 turbine disc with different service times from 0 to 4229 h was investigated at 738 and 823 K. No notable change in microstructural features, other than the increase in grain size, was observed with increasing service time. With increasing service time from 0 to 4229 h, the fatigue crack propagation rates tended to increase, while the ΔK{sub th} value decreased, in low ΔK regime and lower Paris' regime at both testing temperatures. The fractographic observation using a scanning electron microscope suggested that the elevated temperature fatigue crack propagation mechanism of Inconel 718 changed from crystallographic cleavage mechanism to striation mechanism in the low ΔK regime, depending on the grain size. The fatigue crack propagation mechanism is proposed for the crack propagating through small and large grains in the low ΔK regime, and the fatigue crack propagation behavior of Inconel 718 with different service times at elevated temperatures is discussed. - Highlights: • The specimens were prepared from the Inconel 718 turbine disc used for 0 to 4229 h. • FCP rates were measured at 738 and 823 K. • The ΔK{sub th} values decreased with increasing service time. • The FCP behavior showed a strong correlation with the grain size of used turbine disc.

  5. Thermal Failure of Nanostructured Thermal Barrier Coatings with Cold-Sprayed Nanostructured NiCrAlY Bond Coat

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Li, Chang-Jiu; Li, Yong; Zhang, Shao-Ling; Wang, Xiu-Ru; Yang, Guan-Jun; Li, Cheng-Xin

    2008-12-01

    Nanostructured thermal barrier coatings (TBCs) were deposited by plasma spraying using agglomerated nanostructured YSZ powder on Inconel 738 substrate with cold-sprayed nanostructured NiCrAlY powder as bond coat. The isothermal oxidation and thermal cycling tests were applied to examine failure modes of plasma-sprayed nanostructured TBCs. For comparison, the TBC consisting of conventional microstructure YSZ and conventional NiCrAlY bond coat was also deposited and subjected to the thermal shock test. The results showed that nanostructured YSZ coating contained two kinds of microstructures; nanosized zirconia particles embedded in the matrix and microcolumnar grain structures of zirconia similar to those of conventional YSZ. Although, after thermal cyclic test, a continuous, uniform thermally grown oxide (TGO) was formed, cracks were observed at the interface between TGO/BC or TGO/YSZ after thermal cyclic test. However, the failure of nanostructured and conventional TBCs mainly occurred through spalling of YSZ. Compared with conventional TBCs, nanostructured TBCs exhibited better thermal shock resistance.

  6. Exposure of spray-men to dieldrin in residual spraying.

    PubMed

    FLETCHER, T E; PRESS, J M; WILSON, D B

    1959-01-01

    A study of the exposure of spray-men to dieldrin was made in a pilot scheme of residual spraying in the Taveta-Pare area of East Africa. A detailed work study was completed on the operators, and sources of contamination were enumerated. Filter paper pads were placed on the skin and outside clothing and the pick-up was estimated chemically. A spray-man, while using the daily average of 2.12 kg (4.7 pounds) of dieldrin and observing the protective measures laid down, received a dermal exposure of 1.8 mg of dieldrin per kg of body-weight per day. This was possibly reduced somewhat by washing with soap and water upon completion of each day's work. The sixteen spray-men and assistants were exposed for 180 days per year and there was an interim period of 2 months between spray cycles. No clinical symptoms of poisoning were observed.Comparison is made with certain programmes where dieldrin poisoning has occurred. Attention is drawn to the reduced time of exposure in the Taveta-Pare scheme, personal washing, the great value of protective clothing and of its daily washing in soap and water and the need to use a dilute suspension of wettable powder for spraying.

  7. Modifications Of A Commercial Spray Gun

    NASA Technical Reports Server (NTRS)

    Allen, Peter B.

    1993-01-01

    Commercial spray gun modified to increase spray rate and make sprayed coats more nearly uniform. Consists of gun head and pneumatic actuator. Actuator opens valves for two chemical components, called "A" and "B," that react to produce foam. Components flow through orifices, into mixing chamber in head. Mixture then flows through control orifice to spray tip. New spray tip tapered to reduce area available for accumulation of foam and makes tip easier to clean.

  8. Modifications Of A Commercial Spray Gun

    NASA Technical Reports Server (NTRS)

    Allen, Peter B.

    1993-01-01

    Commercial spray gun modified to increase spray rate and make sprayed coats more nearly uniform. Consists of gun head and pneumatic actuator. Actuator opens valves for two chemical components, called "A" and "B," that react to produce foam. Components flow through orifices, into mixing chamber in head. Mixture then flows through control orifice to spray tip. New spray tip tapered to reduce area available for accumulation of foam and makes tip easier to clean.

  9. Process Sprays Uniforms Plasma Coatings

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.; Jacobson, T. P.; Walther, G. C.; Nakamura, H. H.

    1983-01-01

    Composite-powder processing procedure developed along with plasma-spray parameters to achieve homogeneous, well-bonded, low-porosity, self-lubricating coatings. Multicomponent plasma coatings are applied without segretation of components.

  10. Spray nozzle for fire control

    NASA Astrophysics Data System (ADS)

    Papavergos, Panayiotis G.

    1990-09-01

    The design of a spray nozzle for fire control is described. It produces a spray of gas and liquid having an oval transverse cross section and it comprises a mixing chamber with an oval transverse cross section adapted to induce a toroidal mixing pattern in pressurized gas and liquid introduced to the mixing chamber through a plurality of inlets. In a preferred embodiment the mixing chamber is toroidal. The spray nozzle produces an oval spray pattern for more efficient wetting of narrow passages and is suitable for fire control systems in vehicles or other confined spaces. Vehicles to which this invention may be applied include trains, armoured vehicles, ships, hovercraft, submarines, oil rigs, and most preferably, aircraft.

  11. Effect of Double Aging Heat Treatment on the Short-Term Creep Behavior of the Inconel 718

    NASA Astrophysics Data System (ADS)

    Caliari, Felipe Rocha; Candioto, Kátia Cristiane Gandolpho; Couto, Antônio Augusto; Nunes, Carlos Ângelo; Reis, Danieli Aparecida Pereira

    2016-06-01

    This research studies the effect of double aging heat treatment on the short-term creep behavior of the superalloy Inconel 718. The superalloy, received in the solution treated state, was subjected to an aging treatment which comprises a solid solution at 1095 °C for 1 h, a first aging step of 955 °C for 1 h, then aged at 720 and 620 °C, 8 h each step. Creep tests at constant load mode, under temperatures of 650, 675, 700 °C and stress of 510, 625 and 700 MPa, were performed before and after heat treatment. The results indicate that after the double aging heat treatment creep resistance is increased, influenced by the presence of precipitates γ' and γ″ and its interaction with the dislocations, by grain size growth (from 8.20 to 7.23 ASTM) and the increase of hardness by approximately 98%. Creep parameters of primary and secondary stages have been determined. There is a breakdown relationship between dot{\\upvarepsilon }_{{s}} and stress at 650 °C of Inconel 718 as received, around 600 MPa. By considering the internal stress values, effective stress exponent, effective activation energy, and TEM images of Inconel 718 double aged, it is suggested that the creep mechanism is controlled by the interaction of dislocations with precipitates. The fracture mechanism of Inconel 718 as received is transgranular (coalescence of dimples) and mixed (transgranular-intergranular), whereas the Inconel 718 double aged condition crept surfaces evidenced the intergranular fracture mechanism.

  12. The corrosion behavior and microstructure of high-velocity oxy-fuel sprayed nickel-base amorphous/nanocrystalline coatings

    NASA Astrophysics Data System (ADS)

    Dent, A. H.; Horlock, A. J.; McCartney, D. G.; Harris, S. J.

    1999-09-01

    The corrosion characteristics of two Ni-Cr-Mo-B alloy powders sprayed by the high-velocity oxy-fuel (HVOF) process have been studied using potentiodynamic and potentiostatic corrosion analysis in 0.5 M H2SO4. The deposits were also microstructurally characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM) (utilizing both secondary electron and backscattered electron modes), and transmission electron microscopy (TEM). Results from the microstructural examination of the two alloys have revealed a predominantly amorphous/nanocrystalline face centered cubic (fcc) matrix containing submicron boride precipitates as well as regions of martensitically transformed laths. Apparent recrystallization of the amorphous matrix has also been observed in the form of cellular crystals with a fcc structure. The oxide stringers observed at splat boundaries were found to be columnar grained α-Cr2O3, though regions of the spinel oxide NiCr2O4 with a globular morphology were also observed. The coatings of the two alloys exhibited comparable resistance to corrosion in 0.5 M H2SO4, as revealed by potentiodynamic tests. They both had rest potentials approximately equal to -300 mV saturated calomel electrode (SCE) and passive region current densities of ˜1 mA/cm2. Microstructural examination of samples tested potentiostatically revealed the prevalence of degradation at splat boundaries, especially those where significant oxidation of the deposit occurred.

  13. Marine Applications of Thermal Spray Technology Hard Chrome Alternatives Team Meeting

    DTIC Science & Technology

    2006-01-25

    Cable Laying Ship AFTER REPAIR – 26” Diameter Ring GATE VALVE – 12” BEFORE REPAIR AFTER REPAIR Seat Surface Repaired With HVOF Applied Tungsten Carbide...Tungsten Carbide BEFORE AFTER BUTTERFLY VALVE STEM New Shaft Coated With HVOF Applied Tungsten Carbide To Prevent Wear OLD VALVE STEM NEW VALVE STEM WITH...Shafts • Rudder Posts • Valve Stems • Main Propulsion Shafts • Plungers • Mandrels • Packing Glands INNOVATION ! EXPERIENCE ! QUALITY

  14. Microchip sonic spray ionization.

    PubMed

    Pól, Jaroslav; Kauppila, Tiina J; Haapala, Markus; Saarela, Ville; Franssila, Sami; Ketola, Raimo A; Kotiaho, Tapio; Kostiainen, Risto

    2007-05-01

    The first microchip version of sonic spray ionization (SSI) as an atmospheric pressure ionization source for mass spectrometry (MS) is presented. The microchip used for SSI has recently been developed in our laboratory, and it has been used before as an atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) source. Now the ionization is achieved simply by applying high (sonic) speed nebulizer gas, without heat, corona discharge, or high voltage. The microchip SSI was applied to the analysis of tetra-N-butylammonium, verapamil, testosterone, angiotensin I, and ibuprofen. The limits of detection were in the range of 15 nM to 4 microM. The technique was found to be highly dependent on the position of the chip toward the mass spectrometer inlet, and on the gas and the sample solution flow rates. The microchip SSI provided dynamic linearity following a pattern similar to that used with electrospray, good quantitative repeatability (RSD=16%), and long-term signal stability.

  15. Microstructure and Properties of Cu Coating Fabricated onto Diamond-Cu Substrate by Low-Temperature HVOF Process

    NASA Astrophysics Data System (ADS)

    Liu, Min; Yang, Kun; Deng, Chun-ming; Deng, Chang-guang; Zhou, Ke-song

    2016-12-01

    Diamond-Cu composites have been considered to be the next generation of electronic packing materials. One of the key stumbles for such an application is the joining problem between diamond-Cu composites and other materials due to the poor wettability of the diamond particles in the composites. In order to overcome this hurdle, pure Cu powder was thermally sprayed onto diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process. Microstructure and some fundamental properties of the coating obtained were systematically investigated, and morphologies of the single splat deposited on the diamond-Cu substrate were also observed. The splats obtained have good adhesion with the substrate as fine particles flattened sufficiently, while the coarse particles were significantly deformed. The coating was quite dense with porosity lower than 1%, oxygen content under 0.5% and thermal conductivity about 266 Wm-1 K-1 and still remained on the diamond-Cu substrate after 50 thermal shock cycles between 300 °C and water bath at room temperature. Meanwhile, the solderability of the coating was significantly improved. Therefore, Cu coating deposited on diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process can be beneficial in electronic industry assisting with soldering and improved wettability for joining of other materials.

  16. Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

    SciTech Connect

    Mohd, S. M.; Abd, M. Z.; Abd, A. N.

    2010-03-11

    The plasma sprayed hydroxyapatite (HA) coatings are used on metallic implants to enhance the bonding between the implant and bone in human body. The coating process was implemented at different spraying power for each spraying condition. The coatings formed from a rapid solidification of molten and partly molten particles that impact on the surface of substrate at high velocity and high temperature. The study was concentrated on different spraying power that is between 23 to 31 kW. The effect of different power on the coatings microstructure was investigated using scanning electron microscope (SEM) and phase composition was evaluated using X-ray diffraction (XRD) analysis. The coatings surface morphology showed distribution of molten, partially melted particles and some micro-cracks. The produced coatings were found to be porous as observed from the cross-sectional morphology. The coatings XRD results indicated the presence of crystalline phase of HA and each of the patterns was similar to the initial powder. Regardless of different spraying power, all the coatings were having similar XRD patterns.

  17. Effect of single aging on stress corrosion cracking susceptibility of INCONEL X-750 under PWR conditions

    NASA Astrophysics Data System (ADS)

    Mishra, B.; Moore, J. J.

    1988-05-01

    Unfavorable morphology of precipitates and inclusions has been thought to be the cause of severe intergranular stress corrosion cracking (IGSCC) in double aged INCONEL* X-750 alloy used in reactor water environments. A single step aging treatment of 200 hours at 811 °C followed by furnace cooling after solution treating for 2 hours at 1075 °C has been found to provide an improved combination of strength, ductility, and resistance to SCC under simulated PWR test conditions. In this single aged condition a reprecipitated secondary carbide, together with γ' was produced at the grain boundary which resulted in a mixed fracture mode comprising dimple rupture and microvoid coalescence compared with a predominantly intergranular mode for the fully age hardened specimens. This improvement has been explained in terms of the morphology of the second phase precipitates which are produced in these heat treatment regimes.

  18. Dislocation development and void formation during electron irradiation in inconel X-750 with γ' precipitates

    NASA Astrophysics Data System (ADS)

    Kato, Takahiko; Nakata, Kiyotomo; Takahashi, Heishichiro; Ohnuki, Soumei; Masaoka, Isao; Takeyama, Taro

    1985-08-01

    Swelling behaviour and dislocation development in aged Inconel X-750 containing γ' precipitates during electron irradiation at temperatures of 673 to 823 K were continuously observed with a high voltage electron microscope. In the specimens with large γ', aged above 1073 K for 24 h, the void formation is drastically suppressed at temperatures of 710 to 760 K. The dislocation density in the matrix away from the large γ' is fairly low, although the dislocations tangle around the γ'. In the specimens with fine γ', aged for about 24 h at temperatures below 1023 K, fairly large swelling of 1-1.5% occurs after 20 dpa irradiation at 735 K. The dislocations climb through the fine γ ' and the dislocation density in the matrix increases rapidly with irradiation dose.

  19. Tensile behavior of inconel alloy X-750 in air and vacuum at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Pandey, M. C.; Taplin, D. M. R.; Mukherjee, A. K.

    1984-09-01

    Investigations carried out on the hot tensile properties of Inconel alloy X-750 at 700 °C in air and vacuum at different strain rates, in the range of 1 × 10-7 to 1.2 × 10-6 s-1, have shown that testing in air had a weakening effect on properties. Creep ductility in vacuum ( p 02 = 2.7 × 10-5 Pa) did not change appreciably with strain rate, but ductility varied markedly when tested in the air. Further, the ductility minimum occurred at 625 °C in air whereas considerable improvements in the creep ductilities were observed at 575 °C and 625 °C in the vacuum. The results indicated that the environmental interaction during testing enhanced the rate of cavitation damage causing premature failure in the material.

  20. Effect of Environment on Fatigue and Creep Crack Growth in Inconel X-750 at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Gabrielli, F.; Pelloux, R. M.

    1982-06-01

    The fatigue crack growth rates (FCGR) of Inconel X-750 were measured in air and in vacuum at 25 °C and 650 °C as a function of test frequency. The wave shape was triangular and the frequency varied from 10 Hz to 0.01 Hz. The creep crack growth rates (CCGR) were also measured on single edge notch specimens at 650 °C in air and in purified argon. For a given AK, the FCGR increases when temperature increases and frequency decreases. At low frequency the FCGR approach the creep crack growth rates. The mode of fracture changes from transgranular at 10 Hz to intergranular at 0.01 Hz. The effect of air environment is to accelerate the transition from transgranular to intergranular fracture modes with decreasing frequency. The role of oxidation in accelerating crack growth rate in fatigue and in creep is discussed in detail.

  1. Preliminary investigation of heat transfer to water flowing in an electrically heated Inconel tube

    NASA Technical Reports Server (NTRS)

    Kaufman, Samuel J; Isely, Francis D

    1950-01-01

    A heat-transfer investigation was conducted with water flowing in an electrically heated Inconel tube with an inside diameter of 0.204 inch and a length-diameter ratio of 50 for ranges of Reynolds number up to 100,000 and of entrance pressure up to 200 inches of mercury gage. Correlation of average heat-transfer coefficients was obtained by use of the familiar Nusselt relation, wherein the physical properties of water were evaluated at an average bulk temperature. For conditions in which no boiling occurred, the data gave a good correlation. Runs made in the nucleate-boiling region, however, gave higher values of heat-transfer coefficient than would be predicted by the Nusselt relation.

  2. Neutron Diffraction Characterization of Residual Strain in Welded Inconel 718 for NASA Space Shuttle Flow Liners

    SciTech Connect

    Rathod, C.R.; Vaidyanathan, R.; Livescu, V.; Clausen, B.; Bourke, M. A. M.; Notardonato, W.U.; Femminineo, M.

    2004-06-28

    This work quantitatively assesses residual strains and stresses associated with the weld repair process used to repair cracks on NASA's space shuttle flow liners. The coupons used in this investigation were made of the same INCONEL 718 alloy used for the flow liners. They were subjected to identical welding and certification procedures that were carried out on the space shuttle. Neutron diffraction measurements at Los Alamos National Laboratory determined residual strains at selected locations in a welded coupon at 293 K and 135 K. The weld repair process introduced Mises effective residual stresses of up to 555 MPa. On comparing the measurements at 293 K and 135 K, no significant change to the residual strain profile was noted at the low temperature. This indicated minimal mismatch in the coefficients of thermal expansion between the base metal and the weld.

  3. Crystallographic texture engineering through novel melt strategies via electron beam melting: Inconel 718

    SciTech Connect

    Dehoff, Ryan R.; Kirka, Michael M.; List, III, Frederick Alyious; Unocic, Kinga A.; Sames, William J.

    2014-01-01

    Preliminary research has demonstrated the ability to utilise novel scan strategies in the electron beam melting (EBM) process to establish control of crystallographic texture within Inconel 718 deposits. Conventional EBM scan strategies and process parameters yield coarse columnar grains aligned parallel to the build direction. Through varying process parameters such as beam power, beam velocity, beam focus and scan strategy, the behaviour of the electron beam can be manipulated from a line source to a point source. The net effect of these variations is that the resulting crystallographic texture is controlled in a manner to produce either epitaxial deposits or fully equiaxed deposits. Furthermore, this research demonstrates the ability to change the crystallographic texture on the macroscale indicating that EBM technology can be used to create complex geometric components with both site-specific microstructures and material properties.

  4. Investigation on edge joints of Inconel 625 sheets processed with laser welding

    NASA Astrophysics Data System (ADS)

    Caiazzo, F.; Alfieri, V.; Cardaropoli, F.; Sergi, V.

    2017-08-01

    Laser welding of Inconel 625 edge joint beads in square groove configuration was investigated. The use of different weld geometries in new aerospace solutions explains research on edge joints. A structured plan was carried out in order to characterize the process defining the influence of laser power and welding speed and to study possible interactions among the governing factors. As weld pool protection is crucial in order to obtain sound joints when processing superalloys, a special glove box for gas supply was designed to upgrade the welding head. Welded joints were characterized referring to bead profile, microstructure and X-rays. It was found that heat input plays an important role as it affects welding stability, porosity content and bead shape. Results suggest operating with low values of heat input to reduce porosity and guarantee stable bead conformation. Furthermore, a decrease in the grain size has been observed as a consequence of decreasing heat input.

  5. The effects of multiple repairs on Inconel 718 weld mechanical properties

    NASA Technical Reports Server (NTRS)

    Russell, C. K.; Nunes, A. C., Jr.; Moore, D.

    1991-01-01

    Inconel 718 weldments were repaired 3, 6, 9, and 13 times using the gas tungsten arc welding process. The welded panels were machined into mechanical test specimens, postweld heat treated, and nondestructively tested. Tensile properties and high cycle fatigue life were evaluated and the results compared to unrepaired weld properties. Mechanical property data were analyzed using the statistical methods of difference in means for tensile properties and difference in log means and Weibull analysis for high cycle fatigue properties. Statistical analysis performed on the data did not show a significant decrease in tensile or high cycle fatigue properties due to the repeated repairs. Some degradation was observed in all properties, however, it was minimal.

  6. High-rate laser metal deposition of Inconel 718 component using low heat-input approach

    NASA Astrophysics Data System (ADS)

    Kong, C. Y.; Scudamore, R. J.; Allen, J.

    Currently many aircraft and aero engine components are machined from billets or oversize forgings. This involves significant cost, material wastage, lead-times and environmental impacts. Methods to add complex features to another component or net-shape surface would offer a substantial cost benefit. Laser Metal Deposition (LMD), currently being applied to the repair of worn or damaged aero engine components, was attempted in this work as an alternative process route, to build features onto a base component, because of its low heat input capability. In this work, low heat input and high-rate deposition was developed to deposit Inconel 718 powder onto thin plates. Using the optimised process parameters, a number of demonstrator components were successfully fabricated.

  7. Thermal Effects on Microstructural Heterogeneity of Inconel 718 Materials Fabricated by Electron Beam Melting

    SciTech Connect

    Sames, William J.; Unocic, Kinga A.; Dehoff, Ryan R.; Lolla, Tapasvi; Babu, Sudarsanam Suresh

    2014-07-28

    Additive manufacturing (AM) technologies, also known as 3D printing, have demonstrated the potential to fabricate complex geometrical components, but the resulting microstructures and mechanical properties of these materials are not well understood due to unique and complex thermal cycles observed during processing. The electron beam melting (EBM) process is unique because the powder bed temperature can be elevated and maintained at temperatures over 1000 °C for the duration of the process. This results in three specific stages of microstructural phase evolution: (a) rapid cool down from the melting temperature to the process temperature, (b) extended hold at the process temperature, and (c) slow cool down to the room temperature. In this work, the mechanisms for reported microstructural differences in EBM are rationalized for Inconel 718 based on measured thermal cycles, preliminary thermal modeling, and computational thermodynamics models. The relationship between processing parameters, solidification microstructure, interdendritic segregation, and phase precipitation (δ, γ´, and γ´´) are discussed.

  8. Electron Backscatter Diffraction Analysis of Inconel 718 Parts Fabricated by Selective Laser Melting Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoqing; Chou, Kevin

    2017-02-01

    In this study, the crystallographic texture of an Inconel 718 part fabricated by selective laser melting was investigated. The front surface (X-Z plane) microstructure is characterized by the columnar grains growing along the build direction, and the width of columnar grains is in the range of about 75-150 µm, with the bottom layers having narrower grains as a result of a higher cooling rate. In addition to equiaxed grains, the top surface (X-Y plane) has a feature of patch patterns resulting from the laser scanning strategy. Based on the electron backscatter diffraction results, there appears only weak crystallographic texture in both the X-Z plane and the X-Y plane of the part. From the grain boundary map, the microstructures are composed of high-angle boundaries with a larger fraction of subgrain boundaries.

  9. Elevated Temperature Strength of Fine-Grained INCONEL Alloy MA754

    SciTech Connect

    T.C. Totemeier; T.M. Lillo; J.A. Simpson

    2005-09-01

    Elevated temperature tensile and creep-rupture tests were performed on INCONEL alloy MA754 in an as-rolled, fine-grained condition. Tensile tests were performed at 25, 800, 900, and 1000°C; creep-rupture tests were performed at 800, 900, and 1000°C. The elevated temperature strength in the fine-grained condition was approximately 25% of the standard, coarse-grained annealed condition. While good ductility was observed in tensile tests at a nominal strain rate of 1×10-3 sec-1, ductility in creep-rupture tests was very low, with failure elongations less than 5% and no reduction in area. Creep deformation appeared to occur solely by cavity formation and growth.

  10. Properties of Inconel 625 Mesh Structures Grown by Electron Beam Additive Manufacturing

    SciTech Connect

    List III, Frederick Alyious; Dehoff, Ryan R; Lowe, Larry E; Sames, William J

    2014-01-01

    Relationships between electron beam parameters (beam current, beam speed, and beam focus) and physical properties (mass, diameter, elastic modulus, and yield strength) have been investigated for Inconel 625 mesh cubes fabricated using an additive manufacturing technology based on electron beam melting. The elastic modulus and yield strength of the mesh cubes have been systematically varied by approximately a factor of ten by changing the electron beam parameters. Simple models have been used to understand better these relationships. Structural anisotropies of the mesh associated with the layered build architecture have been observed and may contribute, along with microstructural anisotropies, to the anisotropic mechanical properties of the mesh. Knowledge of this kind is likely applicable to other metal and alloy systems and is essential to rapidly realize the full potential of this burgeoning technology.

  11. Deformation characteristics of {delta} phase in the delta-processed Inconel 718 alloy

    SciTech Connect

    Zhang, H.Y.; Zhang, S.H.; Cheng, M.; Li, Z.X.

    2010-01-15

    The hot working characteristics of {delta} phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 deg. C and strain rate of 0.005 s{sup -1}, were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like {delta} phase and the precipitation of spherical {delta} phase particles coexisted during the deformation, and the content of {delta} phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like {delta} phase was spheroidized and transferred to spherical {delta} phase particles. In the center with largest strain, the plate-like {delta} phase disappeared and spherical {delta} phase appeared in the interior of grains and grain boundaries.

  12. Microstructural and chemical characterization of the inconel/ti(n) thin film and multilayer system.

    PubMed

    Diehl, P E; Pew, H K; Madsen, D W; Leavitt, J A; Smith, D J

    1995-01-01

    Single layer and multilayer films of titanium and Inconel 600 (76 at.% Ni, 16 at.% Cr, 8 at.% Fe) have been prepared by sputtering in argon/nitrogen atmospheres, with nitrogen partial pressures ranging from 0% to 40%. The microstructure and chemistry of the sputtered films were characterized using transmission/high-resolution electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, electron probe microanalysis, and ion beam analysis with MeV helium beams. The microstructure depended on deposition power and individual layer thickness, as well as the sputtering atmosphere composition. Metal nitrides were formed in single layers of both materials whereas, for multilayers, nitrogen was preferentially incorporated into the titanium layer.

  13. Performance of Silicon carbide whisker reinforced ceramic inserts on Inconel 718 in end milling process

    NASA Astrophysics Data System (ADS)

    Reddy, M. M.; Joshua, C. X. H.

    2016-03-01

    An experimental investigation is planned in order to study the machinability of Inconel 718 with silicon carbide whisker reinforced ceramic inserts in end milling process. The relationship between the cutting speed, feed rate, and depth of cut against the response factors are studied to show the level of significance of each parameter. The cutting parameters are optimized by using Taguchi method. Implementing analysis of variance, the parameter which influences the surface roughness the most is determined to be the cutting speed, followed by the feed rate and depth of cut. Meanwhile, the optimal cutting condition is determined to have high cutting speed, low feed rate, and high depth of cut in the range of selected parameters.

  14. Inter- and intragranular delta phase quantitative characterization in Inconel 718 by means of image analysis.

    PubMed

    Vanderesse, N; Anderson, M; Bridier, F; Bocher, P

    2015-01-01

    This paper describes an image processing method for discriminating the inter- and intragranular delta phase precipitates in Inconel 718 (IN 718). The successive practical operations and the motivations of their choices are presented in detail. The method was applied to IN 718 specimens heat treated with different parameters to produce microstructures containing various amounts of both types of precipitates. They were characterized by electron microscopy in backscattered electron imaging. The main difficulty arose from the fact that the brightness distributions of inter- and intragranular precipitates partially overlap. Additional information on their morphology and their spatial distribution had to be exploited in order to differentiate them. The shape and the orientation of the precipitates were evaluated using the structure tensor, an operator that quantifies the directionality of the intensity distribution in an image. The distance between parallel precipitates was also used as an additional property to identify clusters of intragranular precipitates.

  15. Study of delta phase on static recrystallization behavior of Inconel 718 alloy.

    PubMed

    Lee, Hwa-Teng; Hou, Wen-Hsin

    2012-09-01

    The mechanical properties of Inconel 718 alloy depend on its microstructural features. Controlling the grain size during manufacturing is currently achieved through the use of a powerful hot forming process performed at a temperature sufficiently high to induce dynamic recrystallization. The present study proposes an alternative technique to achieve a uniform fine grain structure by using static recrystallization and a proper control of delta precipitation. The results show that a fine structure with an average grain size of ASTM No. 7 can be achieved. And in this study the finest grains yet achievable is ca. 200 nm. As a result, the proposed technique provides a feasible means of controlling the grain size without the need for an energy consumption and technically sophisticated hot forming process.

  16. Crystallographic texture engineering through novel melt strategies via electron beam melting: Inconel 718

    DOE PAGES

    Dehoff, Ryan R.; Kirka, Michael M.; List, III, Frederick Alyious; ...

    2014-01-01

    Preliminary research has demonstrated the ability to utilise novel scan strategies in the electron beam melting (EBM) process to establish control of crystallographic texture within Inconel 718 deposits. Conventional EBM scan strategies and process parameters yield coarse columnar grains aligned parallel to the build direction. Through varying process parameters such as beam power, beam velocity, beam focus and scan strategy, the behaviour of the electron beam can be manipulated from a line source to a point source. The net effect of these variations is that the resulting crystallographic texture is controlled in a manner to produce either epitaxial deposits ormore » fully equiaxed deposits. Furthermore, this research demonstrates the ability to change the crystallographic texture on the macroscale indicating that EBM technology can be used to create complex geometric components with both site-specific microstructures and material properties.« less

  17. Texture-Induced Anisotropy in an Inconel 718 Alloy Deposited Using Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Tayon, W.; Shenoy, R.; Bird, R.; Hafley, R.; Redding, M.

    2014-01-01

    A test block of Inconel (IN) 718 was fabricated using electron beam freeform fabrication (EBF(sup 3)) to examine how the EBF(sup 3) deposition process affects the microstructure, crystallographic texture, and mechanical properties of IN 718. Tests revealed significant anisotropy in the elastic modulus for the as-deposited IN 718. Subsequent tests were conducted on specimens subjected to a heat treatment designed to decrease the level of anisotropy. Electron backscatter diffraction (EBSD) was used to characterize crystallographic texture in the as-deposited and heat treated conditions. The anisotropy in the as-deposited condition was strongly affected by texture as evidenced by its dependence on orientation relative to the deposition direction. Heat treatment resulted in a significant improvement in modulus of the EBF(sup 3) product to a level nearly equivalent to that for wrought IN 718 with reduced anisotropy; reduction in texture through recrystallization; and production of a more homogeneous microstructure.

  18. Preliminary study on pressure brazing and diffusion welding of Nb-1Zr to Inconel 718

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1990-01-01

    Future space power systems may include Nb-1Zr/Inconel 718 dissimilar metal joints for operation at 1000 K for 60,000 h. The serviceability of pressure-brazed and diffusion-welded joints was investigated. Ni-based metallic glass foil filler metals were used for brazing. Ni and Fe foils were used as diffusion welding inter-layers. Joint soundness was determined by metallographic examination in the as-brazed and as-welded condition, after aging at 1000 K, and after thermal cycling. Brazed joints thermally cycled in the as-brazed condition and diffusion-welded joints were unsatisfactory because of cracking problems. Brazed joints may meet the service requirements if the joints are aged at 1000 K prior to thermal cycling.

  19. Rationalization of Microstructure Heterogeneity in INCONEL 718 Builds Made by the Direct Laser Additive Manufacturing Process

    NASA Astrophysics Data System (ADS)

    Tian, Yuan; McAllister, Donald; Colijn, Hendrik; Mills, Michael; Farson, Dave; Nordin, Mark; Babu, Sudarsanam

    2014-09-01

    Simulative builds, typical of the tip-repair procedure, with matching compositions were deposited on an INCONEL 718 substrate using the laser additive manufacturing process. In the as-processed condition, these builds exhibit spatial heterogeneity in microstructure. Electron backscattering diffraction analyses showed highly misoriented grains in the top region of the builds compared to those of the lower region. Hardness maps indicated a 30 pct hardness increase in build regions close to the substrate over those of the top regions. Detailed multiscale characterizations, through scanning electron microscopy, electron backscattered diffraction imaging, high-resolution transmission electron microscopy, and ChemiSTEM, also showed microstructure heterogeneities within the builds in different length scales including interdendritic and interprecipitate regions. These multiscale heterogeneities were correlated to primary solidification, remelting, and solid-state precipitation kinetics of γ″ induced by solute segregation, as well as multiple heating and cooling cycles induced by the laser additive manufacturing process.

  20. Electron Backscatter Diffraction Analysis of Inconel 718 Parts Fabricated by Selective Laser Melting Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoqing; Chou, Kevin

    2016-11-01

    In this study, the crystallographic texture of an Inconel 718 part fabricated by selective laser melting was investigated. The front surface (X-Z plane) microstructure is characterized by the columnar grains growing along the build direction, and the width of columnar grains is in the range of about 75-150 µm, with the bottom layers having narrower grains as a result of a higher cooling rate. In addition to equiaxed grains, the top surface (X-Y plane) has a feature of patch patterns resulting from the laser scanning strategy. Based on the electron backscatter diffraction results, there appears only weak crystallographic texture in both the X-Z plane and the X-Y plane of the part. From the grain boundary map, the microstructures are composed of high-angle boundaries with a larger fraction of subgrain boundaries.

  1. Preliminary study on pressure brazing and diffusion welding of Nb-1Zr to Inconel 718

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1990-01-01

    Future space power systems may include Nb-1Zr/Inconel 718 dissimilar metal joints for operation at 1000 K for 60,000 h. The serviceability of pressure-brazed and diffusion-welded joints was investigated. Ni-based metallic glass foil filler metals were used for brazing. Ni and Fe foils were used as diffusion welding inter-layers. Joint soundness was determined by metallographic examination in the as-brazed and as-welded condition, after aging at 1000 K, and after thermal cycling. Brazed joints thermally cycled in the as-brazed condition and diffusion-welded joints were unsatisfactory because of cracking problems. Brazed joints may meet the service requirements if the joints are aged at 1000 K prior to thermal cycling.

  2. Processing and Characterization of Sub-delta Solvus Forged Hemispherical Forgings of Inconel 718

    NASA Astrophysics Data System (ADS)

    Chenna Krishna, S.; Rao, G. Sudarasana; Singh, Satish Kumar; Narayana Murty, S. V. S.; Venkatanarayana, G.; Jha, Abhay K.; Pant, Bhanu; Venkitakrishnan, P. V.

    2016-12-01

    In this paper, microstructure and mechanical properties of 200 mm diameter Inconel 718 hemispherical domes processed at 1025 °C through closed die hammer forging have been investigated. Microstructure and mechanical properties of the forgings in radial and tangential directions were characterized using optical microscopy, scanning electron microscopy, impact testing, and tensile testing. Grain size of the forgings at three different locations was fine with an average grain size of ASTM No. 8-9. The typical tensile properties of the forgings in solution-treated and aged condition were ultimate tensile strength-1450 MPa, yield strength-1240 MPa, and ductility-25%. The fine grain size achieved in forgings has been attributed to delta phase present at grain boundaries which pinned the grains during forging and prevented grain coarsening.

  3. Comparison of the performance between a spray gun and a spray boom in ornamentals.

    PubMed

    Foqué, D; Nuyttens, D

    2011-01-01

    Flemish greenhouse growers predominantly use handheld spray guns and spray lances for their crop protection purposes although these techniques are known for their heavy workload and their high operator exposure risks. Moreover, when these techniques are compared with spray boom equipment, they are often found to be less effective. On the other hand, handheld spraying techniques are less expensive and more flexible to use. Additionally, many Flemish growers are convinced that a high spray volume and spray pressure is needed to assure a good plant protection. The aim of this work was to evaluate and compare the spray deposition, penetration and uniformity between a manually pulled horizontal spray boom and a spray gun under controlled laboratory conditions. In total, six different spray application techniques were evaluated. In general, the total deposition results were comparable between the spray boom and the spray gun applications but the boom applications resulted in a more uniform spray distribution over the crop. On a plant level, the spray distribution was not uniform for the different techniques with highest deposits on the upper side of the top leaves. Using spray guns at a higher spray pressure did not improve spray penetration and deposition on the bottom side of the leaves. From the different nozzle types, the XR 80 03 gave the best results. Plant density clearly affected crop penetration and deposition on the bottom side of the leaves.

  4. Microstructural evolution of CANDU spacer material Inconel X-750 under in situ ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, He Ken; Yao, Zhongwen; Judge, Colin; Griffiths, Malcolm

    2013-11-01

    Work on Inconel®Inconel® is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys.1 X-750 spacers removed from CANDU®CANDU® is a registered trademark of Atomic Energy of Canada Limited standing for ''CANada Deuterium Uranium''.2 reactors has shown that they become embrittled and there is development of many small cavities within the metal matrix and along grain boundaries. In order to emulate the neutron irradiation induced microstructural changes, heavy ion irradiations (1 MeV Kr2+ ions) were performed while observing the damage evolution using an intermediate voltage electron microscope (IVEM) operating at 200 kV. The irradiations were carried out at various temperatures 60-400 °C. The principal strengthening phase, γ‧, was disordered at low doses (˜0.06 dpa) during the irradiation. M23C6 carbides were found to be stable up to 5.4 dpa. Lattice defects consisted mostly of stacking fault tetrahedras (SFTs), 1/2<1 1 0> perfect loops and small 1/3<1 1 1> faulted Frank loops. The ratio of SFT number density to loop number density for each irradiation condition was found to be neither temperature nor dose dependent. Under the operation of the ion beam the SFT production was very rapid, with no evidence for further growth once formed, indicating that they probably formed as a result of cascade collapse in a single cascade. The number density of the defects was found to saturate at low dose (˜0.68 dpa). No cavities were observed regardless of the irradiation temperature between 60 °C and 400 °C for doses up to 5.4 dpa. In contrast, cavities have been observed after neutron irradiation in the same material at similar doses and temperatures indicating that helium, produce during neutron irradiation, may be essential for the nucleation and growth of cavities.

  5. Effect of cold drawing ratio on γ′ precipitation in Inconel X-750

    SciTech Connect

    Ha, Jeong Won; Seong, Baek Seok; Jeong, Hi Won; Yoo, Young Soo; Choi, Yoon Suk; Kang, Namhyun

    2014-10-15

    Inconel X-750 is a Ni-based precipitation-hardened superalloy having large tensile and fracture strengths. In the study, X-750 wires were cold drawn to different extents. Small angle neutron scattering was employed to quantitatively measure the size and volume fraction of the γ′ phase as a function of the cold drawing ratio (DR) and aging temperature. The presence and size of γ′ precipitates were confirmed by transmission electron microscopy. The drawing ratio had an important effect on the volume fraction of the γ′ precipitates. However, the size of the precipitates was independent on the drawing ratio. The specimen with the minimum drawing ratio (DR0) produced the largest volume fraction of γ′ as compared with large drawing ratio (DR) specimens such as DR17 and DR42. The small volume fraction of the γ′ phase for a sizeable drawing ratio was associated with the large amount of nucleation sites for secondary carbides, M{sub 23}C{sub 6}, and the fast diffusion path, i.e., dislocation, needed to form M{sub 23}C{sub 6}. A Cr depletion zone around the secondary carbides raised the solubility of γ′. Therefore, the significant drawing ratio contributing to the large volume fraction of the secondary carbides decreased the volume fraction of the γ′ precipitates in Inconel X-750. - Highlights: • The volume fraction of secondary carbides increased with the drawing ratio. • The volume fraction of γ′ decreased as the drawing ratio increased. • The drawing ratio affected the γ′ volume fraction with no variation of the γ' size. • The volume fraction of γ′ was affected by the secondary carbide volume fraction.

  6. Microstructure and mechanical behavior of direct metal laser sintered Inconel alloy 718

    SciTech Connect

    Smith, Derek H.; Bicknell, Jonathan; Jorgensen, Luke; Patterson, Brian M.; Cordes, Nikolaus L.; Tsukrov, Igor; Knezevic, Marko

    2016-03-15

    In this paper, we investigate microstructure and quasi-static mechanical behavior of the direct metal laser sintered Inconel 718 superalloy as a function of build direction (BD). The printed material was further processed by annealing and double-aging, hot isostatic pressing (HIP), and machining. We characterize porosity fraction and distribution using micro X-ray computed tomography (μXCT), grain structure and crystallographic texture using electron backscattered diffraction (EBSD), and mechanical response in quasi-static tension and compression using standard mechanical testing at room temperature. Analysis of the μXCT imaging shows that majority of porosity develops in the outer layer of the printed material. However, porosity inside the material is also present. The EBSD measurements reveal formation of columnar grains, which favor < 001 > fiber texture components along the BD. These measurements also show evidence of coarse-grained microstructure present in the samples treated by HIP. Finally, analysis of grain boundaries reveal that HIP results in a large number of annealing twins compared to that in samples that underwent annealing and double-aging. The yield strength varies with the testing direction by approximately 7%, which is governed by a combination of grain morphology and crystallographic texture. In particular, we determine tension–compression asymmetry in the yield stress as well as anisotropy of the material flow during compression. We find that HIP lowers yield stress but improves ductility relative to the annealed and aged material. These results are discussed and critically compared with the data reported for wrought material in the same condition. - Highlights: • Microstructure and mechanical properties of DMLS Inconel 718 are studied in function of build direction. • Inhomogeneity of microstructure in the material in several conditions is quantified by μXCT and EBSD. • Anisotropy and asymmetry in the mechanical response are

  7. Miniature paint-spray gun for recessed areas

    NASA Technical Reports Server (NTRS)

    Vanasse, M. A.

    1968-01-01

    Miniature spray gun regulates paints and other liquids to spray at close range, facilitating spraying of remote or recessed areas. Individual valves for regulating air pressure and paint maximizes atomization for low pressure spraying.

  8. SPRAY CALCINATION REACTOR

    DOEpatents

    Johnson, B.M.

    1963-08-20

    A spray calcination reactor for calcining reprocessin- g waste solutions is described. Coaxial within the outer shell of the reactor is a shorter inner shell having heated walls and with open regions above and below. When the solution is sprayed into the irner shell droplets are entrained by a current of gas that moves downwardly within the inner shell and upwardly between it and the outer shell, and while thus being circulated the droplets are calcined to solids, whlch drop to the bottom without being deposited on the walls. (AEC) H03 H0233412 The average molecular weights of four diallyl phthalate polymer samples extruded from the experimental rheometer were redetermined using the vapor phase osmometer. An amine curing agent is required for obtaining suitable silver- filled epoxy-bonded conductive adhesives. When the curing agent was modified with a 47% polyurethane resin, its effectiveness was hampered. Neither silver nor nickel filler impart a high electrical conductivity to Adiprenebased adhesives. Silver filler was found to perform well in Dow-Corning A-4000 adhesive. Two cascaded hot-wire columns are being used to remove heavy gaseous impurities from methane. This purified gas is being enriched in the concentric tube unit to approximately 20% carbon-13. Studies to count low-level krypton-85 in xenon are continuing. The parameters of the counting technique are being determined. The bismuth isotopes produced in bismuth irradiated for polonium production are being determined. Preliminary data indicate the presence of bismuth207 and bismuth-210m. The light bismuth isotopes are probably produced by (n,xn) reactions bismuth-209. The separation of uranium-234 from plutonium-238 solutions was demonstrated. The bulk of the plutonium is removed by anion exchange, and the remainder is extracted from the uranium by solvent extraction techniques. About 99% of the plutonium can be removed in each thenoyltrifluoroacetone extraction. The viscosity, liquid density, and

  9. Spray Above Enceladus

    NASA Image and Video Library

    2005-11-28

    A fine spray of small, icy particles emanating from the warm, geologically unique province surrounding the south pole of Saturn’s moon Enceladus was observed in a Cassini narrow-angle camera image of the crescent moon taken on Jan. 16, 2005. Taken from a high-phase angle of 148 degrees -- a viewing geometry in which small particles become much easier to see -- the plume of material becomes more apparent in images processed to enhance faint signals. Imaging scientists have measured the light scattered by the plume's particles to determine their abundance and fall-off with height. Though the measurements of particle abundance are more certain within 100 kilometers (60 miles) of the surface, the values measured there are roughly consistent with the abundance of water ice particles measured by other Cassini instruments (reported in September, 2005) at altitudes as high as 400 kilometers (250 miles) above the surface. Imaging scientists, as reported in the journal Science on March 10, 2006, believe that the jets are geysers erupting from pressurized subsurface reservoirs of liquid water above 273 degrees Kelvin (0 degrees Celsius). The image at the left was taken in visible green light. A dark mask was applied to the moon's bright limb in order to make the plume feature easier to see. The image at the right has been color-coded to make faint signals in the plume more apparent. Images of other satellites (such as Tethys and Mimas) taken in the last 10 months from similar lighting and viewing geometries, and with identical camera parameters as this one, were closely examined to demonstrate that the plume towering above Enceladus' south pole is real and not a camera artifact. The images were acquired at a distance of about 209,400 kilometers (130,100 miles) from Enceladus. Image scale is about 1 kilometer (0.6 mile) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA07760

  10. Detailed fuel spray analysis techniques

    NASA Technical Reports Server (NTRS)

    Mularz, E. J.; Bosque, M. A.; Humenik, F. M.

    1983-01-01

    Detailed fuel spray analyses are a necessary input to the analytical modeling of the complex mixing and combustion processes which occur in advanced combustor systems. It is anticipated that by controlling fuel-air reaction conditions, combustor temperatures can be better controlled, leading to improved combustion system durability. Thus, a research program is underway to demonstrate the capability to measure liquid droplet size, velocity, and number density throughout a fuel spray and to utilize this measurement technique in laboratory benchmark experiments. The research activities from two contracts and one grant are described with results to data. The experiment to characterize fuel sprays is also described. These experiments and data should be useful for application to and validation of turbulent flow modeling to improve the design systems of future advanced technology engines.

  11. Spray coated nanosilver functional layers

    NASA Astrophysics Data System (ADS)

    Krzemiński, J.; Szałapak, J.; Dybowska-Sarapuk, L.; Jakubowska, M.

    2016-09-01

    Silver coatings are highly conductive functional layers. There are many different ways to product the silver coating but most of them need vacuum or high temperature. Spray coating is a technique that is free of this disadvantages - it doesn't need a cleanroom or high temperature. What's more the layer thickness is about 10 μm. In this article the spray coating process of silver nanolayer is described. Four different inks were tested and measured. The layer resistance was measured and show as a graph. After the layer resistance was measured the adhesion test was performed. The pull-off test was performed on testing machine with special self made module. To conclude the article include the test and measurements of spray coated nanosilver functional layers. The layers was examined for the current conductivity and adhesion force.

  12. [Antibacterial effect of Ankerplast Spray].

    PubMed

    Oehring, H; Karl, P; Döring, K; Herrberger, U

    1979-04-01

    The diffusion test yielded no satisfactory results. In the tube test, both the spray and the solvent (in a dilution of 1:4 and 1:8, respectively) proved to be bacteriostatically active against enterococci, Staphylococcus aureus, Escheria coli, Proteus, and Pseudomonas aeruginosa. These germs were killed within 30 minutes in the test for bactericidal activity, whereas the reference substance (1% phenol) required 1--2 hours, except against the last-named germ. Even the copolymer exerted a bactericidal effect, it is true, but only within 8 or 24 hours. The following results were obtained from the spray test with agar plate cultures: Streptococcus viridans species, streptococci, Diplococcus pneumoniae, Escheria coli, and Proteus were killed, whereas others survived under the plastic film for up to 9 days. Klebsiella and Pseudomonas aeruginosa had grown through the film within 7 days. In vivo experiments demonstrated a very potent antibacterial activity on the skin under the spray film.

  13. The 2016 Thermal Spray Roadmap

    NASA Astrophysics Data System (ADS)

    Vardelle, Armelle; Moreau, Christian; Akedo, Jun; Ashrafizadeh, Hossein; Berndt, Christopher C.; Berghaus, Jörg Oberste; Boulos, Maher; Brogan, Jeffrey; Bourtsalas, Athanasios C.; Dolatabadi, Ali; Dorfman, Mitchell; Eden, Timothy J.; Fauchais, Pierre; Fisher, Gary; Gaertner, Frank; Gindrat, Malko; Henne, Rudolf; Hyland, Margaret; Irissou, Eric; Jordan, Eric H.; Khor, Khiam Aik; Killinger, Andreas; Lau, Yuk-Chiu; Li, Chang-Jiu; Li, Li; Longtin, Jon; Markocsan, Nicolaie; Masset, Patrick J.; Matejicek, Jiri; Mauer, Georg; McDonald, André; Mostaghimi, Javad; Sampath, Sanjay; Schiller, Günter; Shinoda, Kentaro; Smith, Mark F.; Syed, Asif Ansar; Themelis, Nickolas J.; Toma, Filofteia-Laura; Trelles, Juan Pablo; Vassen, Robert; Vuoristo, Petri

    2016-12-01

    Considerable progress has been made over the last decades in thermal spray technologies, practices and applications. However, like other technologies, they have to continuously evolve to meet new problems and market requirements. This article aims to identify the current challenges limiting the evolution of these technologies and to propose research directions and priorities to meet these challenges. It was prepared on the basis of a collection of short articles written by experts in thermal spray who were asked to present a snapshot of the current state of their specific field, give their views on current challenges faced by the field and provide some guidance as to the R&D required to meet these challenges. The article is divided in three sections that deal with the emerging thermal spray processes, coating properties and function, and biomedical, electronic, aerospace and energy generation applications.

  14. Effects of spray adjuvants on spray droplet size from a rotary atomizer

    USDA-ARS?s Scientific Manuscript database

    Rotary atomizers are used in a number of aerial applications, such as forest pest spraying and mosquito control sprays. These types of atomizers have a rotating cage at speeds of 2,000 to 10,000 rpm through which a spray is emitted and atomized. Many applicators routinely add spray adjuvants to ch...

  15. Air and spray mixture temperature effects on atomization of agricultural sprays

    USDA-ARS?s Scientific Manuscript database

    Spray drift associated with agrochemical operations is highly dependent upon the physical properties of the spray solution with respect to how they influence atomization. This study examined effects on spray atomization with two spray solutions across a wide range of solution temperatures for two n...

  16. Fe-Al Weld Overlay and High Velocity Oxy-Fuel Thermal Spray Coatings for Corrosion Protection of Waterwalls in Fossil Fired Plants with Low NOx Burners

    SciTech Connect

    Regina, J.R.

    2002-02-08

    Iron-aluminum-chromium coatings were investigated to determine the best candidates for coatings of boiler tubes in Low NOx fossil fueled power plants. Ten iron-aluminum-chromium weld claddings with aluminum concentrations up to 10wt% were tested in a variety of environments to evaluate their high temperature corrosion resistance. The weld overlay claddings also contained titanium additions to investigate any beneficial effects from these ternary and quaternary alloying additions. Several High-Velocity Oxy-Fuel (HVOF) thermal spray coatings with higher aluminum concentrations were investigated as well. Gaseous corrosion testing revealed that at least 10wt%Al is required for protection in the range of environments examined. Chromium additions were beneficial in all of the environments, but additions of titanium were beneficial only in sulfur rich atmospheres. Similar results were observed when weld claddings were in contact with corrosive slag while simultaneously, exposed to the corrosive environments. An aluminum concentration of 10wt% was required to prevent large amounts of corrosion to take place. Again chromium additions were beneficial with the greatest corrosion protection occurring for welds containing both 10wt%Al and 5wt%Cr. The exposed thermal spray coatings showed either significant cracking within the coating, considerable thickness loss, or corrosion products at the coating substrate interface. Therefore, the thermal spray coatings provided the substrate very little protection. Overall, it was concluded that of the coatings studied weld overlay coatings provide superior protection in these Low NOx environments; specifically, the ternary weld composition of 10wt%Al and 5wt%Cr provided the best corrosion protection in all of the environments tested.

  17. Spray casting project final report

    SciTech Connect

    Churnetski, S.R.; Thompson, J.E.

    1996-08-01

    Lockheed Martin Energy Systems, Inc. (Energy Systems), along with other participating organizations, has been exploring the feasibility of spray casting depleted uranium (DU) to near-net shape as a waste minimization effort. Although this technology would be useful in a variety of applications where DU was the material of choice, this effort was aimed primarily at gamma-shielding components for use in storage and transportation canisters for high-level radioactive waste, particularly in the Multipurpose Canister (MPC) application. In addition to the waste-minimization benefits, spray casting would simplify the manufacturing process by allowing the shielding components for MPC to be produced as a single component, as opposed to multiple components with many fabrication and assembly steps. In earlier experiments, surrogate materials were used to simulate the properties (specifically reactivity and density) of DU. Based on the positive results from those studies, the project participants decided that further evaluation of the issues and concerns that would accompany spraying DU was warranted. That evaluation occupied substantially all of Fiscal Year 1995, yielding conceptual designs for both an intermediate facility and a production facility and their associated engineering estimates. An intermediate facility was included in this study to allow further technology development in spraying DU. Although spraying DU to near-net shape seems to be feasible, a number of technical, engineering, and safety issues would need to be evaluated before proceeding with a production facility. This report is intended to document the results from the spray-casting project and to provide information needed by anyone interested in proceeding to the next step.

  18. Thermal Spray Coatings for Coastal Infrastructure

    SciTech Connect

    Holcomb, G.R.; Covino, BernardS. Jr.; Cramer, S.D.; Bullard, S.J.

    1997-11-01

    Several protection strategies for coastal infrastructure using thermal-spray technology are presented from research at the Albany Research Center. Thermal-sprayed zinc coatings for anodes in impressed current cathodic protection systems are used to extend the service lives of reinforced concrete bridges along the Oregon coast. Thermal-sprayed Ti is examined as an alternative to the consumable zinc anode. Sealed thermal-sprayed Al is examined as an alternative coating to zinc dust filled polyurethane paint for steel structures.

  19. "Teaching" an Industrial Robot To Spray

    NASA Technical Reports Server (NTRS)

    Evans, A. R.; Sweet, G. K.

    1982-01-01

    Teaching device, consisting of spacer rod or tube with three-pointed tip and line level, is used during pattern "teach-in" to make sure that robot manipulator holds spray gun perpendicular to surface to be sprayed and at right distance from it. For slanted surfaces angle adapter is added between spacer rod and line-level indicator. Angle is determined by slope of surface to be sprayed, thus allowing a perpendicular spray pattern against even slanted surfaces.

  20. Mathematical modeling of the gas and powder flow in the (HVOF) systems to optimize their coatings quality

    NASA Technical Reports Server (NTRS)

    Tawfik, Hazem H.

    1996-01-01

    Thermally sprayed coatings have been extensively used to enhance materials properties and provide surface protection against their working environments in a number of industrial applications. Thermal barrier coatings (TBC) are used to reduce the thermal conductivity of aerospace turbine blades and improve the turbine overall thermal efficiency. TBC allows higher gas operating temperatures and lower blade material temperatures due to the thermal insulation provided by these ceramic coatings. In the automotive industry, coatings are currently applied to a number of moving parts that are subjected to friction and wear inside the engine such as pistons, cylinder liners, valves and crankshafts to enhance their wear resistance and prolong their useful operation and lifetime.

  1. Feedback enhanced plasma spray tool

    DOEpatents

    Gevelber, Michael Alan; Wroblewski, Donald Edward; Fincke, James Russell; Swank, William David; Haggard, Delon C.; Bewley, Randy Lee

    2005-11-22

    An improved automatic feedback control scheme enhances plasma spraying of powdered material through reduction of process variability and providing better ability to engineer coating structure. The present inventors discovered that controlling centroid position of the spatial distribution along with other output parameters, such as particle temperature, particle velocity, and molten mass flux rate, vastly increases control over the sprayed coating structure, including vertical and horizontal cracks, voids, and porosity. It also allows improved control over graded layers or compositionally varying layers of material, reduces variations, including variation in coating thickness, and allows increasing deposition rate. Various measurement and system control schemes are provided.

  2. Recyclability Study on Inconel 718 and Ti-6Al-4V Powders for Use in Electron Beam Melting

    NASA Astrophysics Data System (ADS)

    Nandwana, Peeyush; Peter, William H.; Dehoff, Ryan R.; Lowe, Larry E.; Kirka, Michael M.; Medina, Francisco; Babu, Sudarsanam S.

    2016-02-01

    Powder bed-based additive manufacturing technologies offer a big advantage in terms of reusability of the powders over multiple cycles that result in cost savings. However, currently there are no standards to determine the factors that govern the powder reuse times. This work presents the results from a recyclability study conducted on Inconel 718 and Ti-6Al-4V powders. It has been found that the Inconel 718 powders are chemically stable over a large number of cycles and their reuse time is limited by physical characteristics of powders such as flowability. Ti-6Al-4V, on the other hand, finds its reuse time governed by the oxygen pick up that occurs during and in between build cycles. The detailed results have been presented.

  3. Experimental Study of Direct Laser Deposition of Ti-6Al-4V and Inconel 718 by Using Pulsed Parameters

    PubMed Central

    Shah, Kamran; Haq, Izhar Ul; Shah, Shaukat Ali; Khan, Farid Ullah; Khan, Sikander

    2014-01-01

    Laser direct metal deposition (LDMD) has developed from a prototyping to a single metal manufacturing tool. Its potential for creating multimaterial and functionally graded structures is now beginning to be explored. This work is a first part of a study in which a single layer of Inconel 718 is deposited on Ti-6Al-4V substrate. Single layer tracks were built at a range of powder mass flow rates using a coaxial nozzle and 1.5 kW diode laser operating in both continuous and pulsed beam modes. This part of the study focused on the experimental findings during the deposition of Inconel 718 powder on Ti-6Al-4V substrate. Scanning electron microscopy (SEM) and X-ray diffraction analysis were performed for characterization and phase identification. Residual stress measurement had been carried out to ascertain the effects of laser pulse parameters on the crack development during the deposition process. PMID:24592190

  4. Experimental study of direct laser deposition of Ti-6Al-4V and Inconel 718 by using pulsed parameters.

    PubMed

    Shah, Kamran; Izhar Ul Haq; Shah, Shaukat Ali; Khan, Farid Ullah; Khan, Muhammad Tahir; Khan, Sikander

    2014-01-01

    Laser direct metal deposition (LDMD) has developed from a prototyping to a single metal manufacturing tool. Its potential for creating multimaterial and functionally graded structures is now beginning to be explored. This work is a first part of a study in which a single layer of Inconel 718 is deposited on Ti-6Al-4V substrate. Single layer tracks were built at a range of powder mass flow rates using a coaxial nozzle and 1.5 kW diode laser operating in both continuous and pulsed beam modes. This part of the study focused on the experimental findings during the deposition of Inconel 718 powder on Ti-6Al-4V substrate. Scanning electron microscopy (SEM) and X-ray diffraction analysis were performed for characterization and phase identification. Residual stress measurement had been carried out to ascertain the effects of laser pulse parameters on the crack development during the deposition process.

  5. Determination of Constitutive Equation for Thermo-mechanical Processing of INCONEL 718 Through Double Multivariate Nonlinear Regression Analysis

    NASA Astrophysics Data System (ADS)

    Hussain, Mirza Zahid; Li, Fuguo; Wang, Jing; Yuan, Zhanwei; Li, Pan; Wu, Tao

    2015-07-01

    The present study comprises the determination of constitutive relationship for thermo-mechanical processing of INCONEL 718 through double multivariate nonlinear regression, a newly developed approach which not only considers the effect of strain, strain rate, and temperature on flow stress but also explains the interaction effect of these thermo-mechanical parameters on flow behavior of the alloy. Hot isothermal compression experiments were performed on Gleeble-3500 thermo-mechanical testing machine in the temperature range of 1153 to 1333 K within the strain rate range of 0.001 to 10 s-1. The deformation behavior of INCONEL 718 is analyzed and summarized by establishing the high temperature deformation constitutive equation. The calculated correlation coefficient ( R) and average absolute relative error ( AARE) underline the precision of proposed constitutive model.

  6. Recyclability study on Inconel 718 and Ti-6Al-4V powders for use in electron beam melting

    SciTech Connect

    Nandwana, Peeyush; Peter, William H.; Lowe, Larry E.; Dehoff, Ryan R.; Medina, Francisco; Babu, Sudarsanam Suresh; Kirka, Michael M.

    2015-10-20

    In this study, powder bed based additive manufacturing technologies offer a big advantage in terms of reusability of the powders over multiple cycles that result in cost savings. However, currently there are no standards to determine the factors that govern the powder reuse times. This work presents the results from a recyclability study conducted on Inconel 718 and Ti-6Al-4V powders. It has been found that the Inconel 718 powders are chemically stable over a large number of cycles and their reuse time is limited by physical characteristics of powders such as flowability. Ti-6Al-4V, on the other hand, finds its reuse time governed by the oxygen pick up that occurs during and in between build cycles. The detailed results have been presented.

  7. Recyclability study on Inconel 718 and Ti-6Al-4V powders for use in electron beam melting

    DOE PAGES

    Nandwana, Peeyush; Peter, William H.; Lowe, Larry E.; ...

    2015-10-20

    In this study, powder bed based additive manufacturing technologies offer a big advantage in terms of reusability of the powders over multiple cycles that result in cost savings. However, currently there are no standards to determine the factors that govern the powder reuse times. This work presents the results from a recyclability study conducted on Inconel 718 and Ti-6Al-4V powders. It has been found that the Inconel 718 powders are chemically stable over a large number of cycles and their reuse time is limited by physical characteristics of powders such as flowability. Ti-6Al-4V, on the other hand, finds its reusemore » time governed by the oxygen pick up that occurs during and in between build cycles. The detailed results have been presented.« less

  8. A new method for spray deposit assessment

    Treesearch

    Chester M. Himel; Leland Vaughn; Raymond P. Miskus; Arthur D. Moore

    1965-01-01

    Solid fluorescent particles suspended in a spray liquid are distributed in direct proportion to the size of the spray droplets. Use of solid fluorescent particles is the basis of a new method for visual recognition of the size and number of droplets impinging on target and nontarget portions of sprayed areas.

  9. Propeller wash effects on spray drift

    Treesearch

    Steven J. Thompson; Alvin R. Womac; Joseph Mulrooney; Sidney Deck

    2005-01-01

    for aerial spray application, there is some question if off-target drift (both near and far) is influenced by which boom is spraying and the direction of propeller wash rotation. This information may be useful when switching off one boom close to a field boundary. The effect of alternate boom switching and propeller wash direction on aerial spray drift from a turbine-...

  10. How to Use Nasal Pump Sprays

    MedlinePlus

    Using Nasal Pump SpraysBlow your nose gently before using the spray. Prime the pump bottle by spraying it into the air a ... Breathe in quickly while squeezing down on the pump bottle one time. Repeat in other nostril. Do ...

  11. Stress corrosion cracking susceptibility and some electrochemical characteristics of Inconel X-750 in lithiated water at 350°C

    NASA Astrophysics Data System (ADS)

    Sharkawy, S. W.; Xia, Z.; Szklarska-Smialowska, Z.

    1993-03-01

    The stress corrosion cracking (SCC) susceptibility of Inconel X-750 in the as-received (AR) and double aged (DA) conditions was investigated by the slow strain rate test (SSRT) in lithiated hydrogenated water at 350°C. The results showed that the DA condition was more susceptible to SCC than the AR one. Potentiodynamic polarization and AC impedance tests showed that the DA condition was characterized by higher dissolution rate and a lower tendency to passivation than the AR one.

  12. Verification of the stability lobes of Inconel 718 milling by recurrence plot applications and composite multiscale entropy analysis

    NASA Astrophysics Data System (ADS)

    Krzysztof, Kecik; Borowiec, Marek; Rafał, Rusinek

    2016-01-01

    Correctness verification of the stability lobe diagrams of milling process determined by commercial software CutPro 9 is the aim of this work. The analysis is performed for nickel superalloy Inconel 718 which is widely used in aviation industry. A methodology of stability analysis which bases on advanced nonlinear methods such as recurrence plot, recurrence quantifications analysis and composite multiscale entropy analysis are applied to the experimental data. Additionally, a new criterion for the determination of the unstable areas is proposed.

  13. Optimization of Cutting Parameters for Surface Roughness under MQL, using Al2O3 Nanolubricant, during Turning of Inconel 718

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

    Inconel 718 is a nickel-based alloy commonly used due to its excellent mechanical properties at high temperatures and its elevated corrosion resistance. This material however is difficult to machine due to the high temperature generated during machining, which requires efficient lubrication system. Minimum quantity lubrication (MQL) technique is a more efficient and a more environmentally friendly alternative to conventional flooding lubrication technique. The efficiency and efficacy of this lubrication technique can be further enhanced by adding nano particles and surfactant into the base lubricant. There are currently limited number of studies on the application of minimum quantity lubrication (MQL) technique using nanolubricant with added surfactant in the machining of hard-to-machine materials such as Inconel 718. Consequently, this paper aims to optimize the cutting parameters for surface roughness under minimum quantity lubrication (MQL) condition using surfactant-added Al2O3 nanolubricant during the turning of Inconel 718. The effects of cutting speed, depth of cut and feed rate and their two-way interactions on surface roughness are investigated on the basis of the standard Taguchi’s L9 orthogonal array (OA) design of experiment and the results are assessed using analysis of variance (ANOVA) and signal to noise (S/N) ratio methods to determine the optimal cutting parameter settings as well as the level of significance of the cutting parameters. The optimal surface finish can be observed at the cutting speed of 70 m/min, depth of cut of 0.05 mm and feed rate of 0.05 mm/rev with feed rate being the most significant factor to affect surface finish. Through this study, the application of minimum quantity lubrication (MQL) technique using surfactant-added Al2O3 nanolubricant, has been shown to produce desirable surface finish quality on Inconel 718 with additional economic and ecological benefits.

  14. Microstructural Changes in Inconel® 740 After Long-Term Aging in the Presence and Absence of Stress

    DOE PAGES

    Unocic, Kinga A.; Shingledecker, John Paul; Tortorelli, Peter F.

    2014-11-18

    The Ni-based alloy, Inconel® 740, is being extensively examined for use in advanced ultrasupercritical steam boilers because its precipitation-strengthened microstructure appears to offer the necessary creep strength under the high temperatures and pressures (up to 760°C and 35 MPa) needed for high efficiency power generation. However, because this application requires extremely long lifetimes under these conditions (up to 30 years), long-term microstructure stability is a major concern. In this study, results from microstructural analyses of Inconel 740 specimens aged at 700 and 750°C in the presence and absence of creep loading for times up to ~31,000 h are presented. Themore » primary focus was on the development of the eta η (Ni3Ti) phase and coarsening of coherent γ'-Ni3(Al,Ti) precipitates and its depletion near eta/matrix interfaces. Finally, however, despite these processes, Inconel 740 showed adequate long-term microstructural stability to assure adequate creep strength for the intended application.« less

  15. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, Mechanical Fatigue, Creep and Thermal Fatigue Effects

    NASA Technical Reports Server (NTRS)

    Bast, Callie Corinne Scheidt

    1994-01-01

    This thesis presents the on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes four effects that typically reduce lifetime strength: high temperature, mechanical fatigue, creep, and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model's empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for four variables, namely, high temperature, mechanical fatigue, creep, and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using the current version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of mechanical fatigue, creep, and thermal fatigue was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing a combination of mechanical fatigue and high temperature effects by model to the combination by experiment were conducted. Thus, for Inconel 718, the basic model assumption of independence between effects was evaluated. Results from this limited verification study strongly supported this assumption.

  16. Macrotransport-solidification kinetics modeling of equiaxed dendritic growth. Part 2: Computation problems and validation on INCONEL 718 superalloy castings

    SciTech Connect

    Nastac, L.; Stefanescu, D.M.

    1996-12-01

    In Part 1 of the article, a new analytical model that describes solidification of equiaxed dendrites was presented. In this part of the article, the model is used to simulate the solidification of INCONEL 718 superalloy castings. The model was incorporated into a commercial finite-element code, PROCAST. A special procedure called microlatent heat method (MLHM) was used for coupling between macroscopic heat flow and microscopic growth kinetics. A criterion for time-stepping selection in microscopic modeling has been derived in conjunction with MLHM. Reductions in computational (CPU) time up to 90 pct over the classic latent heat method were found by adopting this coupling. Validation of the model was performed against experimental data for an INCONEL 718 superalloy casting. In the present calculations, the model for globulitic dendrite was used. The evolution of fraction of solid calculated with the present model was compared with Scheil`s model and experiments. An important feature in solidification of INCONEL 718 is the detrimental Laves phase. Laves phase content is directly related to the intensity of microsegregation of niobium, which is very sensitive to the evolution of the fraction of solid. It was found that thee is a critical cooling rate at which the amount of Laves phase is maximum. The critical cooling rate is not a function of material parameters (diffusivity, partition coefficient, etc.). It depends only on the grain size and solidification time. The predictions generated with the present model are shown to agree very well with experiments.

  17. Effect of cold rolling and first precipitates on the coarsening behavior of γ″-phases in Inconel 718 alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Jing-ling; Guo, Qian-ying; Liu, Yong-chang; Li, Chong; Yu, Li-ming; Li, Hui-jun

    2016-09-01

    The coarsening behaviors of γ″-phase particles in Inconel 718 alloy aged at 750, 800, and 850°C were investigated by scanning electron microscopy (SEM). Detailed observations and quantitative measurements were conducted to characterize the coarsening behavior of the γ?-phase under various aging conditions. The experimental results indicate that the existence of the δ-phase retards the formation and coarsening of the γ″-phase, without influencing its final particle size or amount. Moreover, when cold rolled with a reduction of 50%, the dimensions of the γ″ particles in Inconel 718 alloy decrease with increasing aging time. Furthermore, the coarsening behavior of the γ″-phase in the Inconel 718 alloy after a normal aging treatment (sample A) and that of the primary δ-phase (sample B) follow the Lifshitz-Slyozov-Wagner (LSW) diffusion-controlled growth theory; the thus-obtained activation energies for the γ″-phase are 292 kJ·mol-1 and 302 kJ·mol-1, respectively.

  18. Experimental and modeling results of creep fatigue life of Inconel 617 and Haynes 230 at 850 C

    SciTech Connect

    Chen, Xiang; Sokolov, Mikhail A; Sham, Sam; ERDMAN III, DONALD L; Busby, Jeremy T; Mo, Kun; Stubbins, James

    2013-01-01

    Creep fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure for both materials decreased under creep fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep fatigue life. The linear damage summation could predict the creep fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep fatigue life prediction results for both materials.

  19. Selective laser melting additive manufactured Inconel 718 superalloy parts: High-temperature oxidation property and its mechanisms

    NASA Astrophysics Data System (ADS)

    Jia, Qingbo; Gu, Dongdong

    2014-10-01

    This work presented a comprehensive study of high-temperature oxidation behaviors and mechanisms of Selective laser melting (SLM) processed Inconel 718 superalloy parts using different methods including isothermal oxidation testing, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The experimental results revealed that the oxidation process of the tested parts processed at a lower volumetric laser energy density experienced the severe spallation. On reasonably increasing the applied volumetric laser energy density, the oxidation kinetics of the as-produced parts obeyed a parabolic law, exhibiting the significantly improved oxidation resistance performance. The constitutional phases within the oxidation film were identified and the corresponding formation mechanisms were elucidated in detail according to the thermodynamic principles. The cross-sectional morphologies of oxidized Inconel 718 parts indicated that the oxidation microstructure mainly consisted of an external oxidation layer and an internal oxidation zone. The oxidation process was controlled by the outward diffusion of oxide forming elements and inward penetration of oxygen, by which the interaction mechanisms between the microstructures and internal oxidation zones were clarified. On the basis of the experimental results and theoretical analyses, the physical oxidation mechanisms were accordingly established to illustrate the oxidation behaviors of SLM-processed Inconel 718 parts at elevated operative temperatures.

  20. Novel microstructural growth in the surface of Inconel 625 by the addition of SiC under electron beam melting

    NASA Astrophysics Data System (ADS)

    Ahmad, M.; Ali, G.; Ahmed, Ejaz; Haq, M. A.; Akhter, J. I.

    2011-06-01

    Electron beam melting is being used to modify the microstructure of the surfaces of materials due to its ability to cause localized melting and supercooling of the melt. This article presents an experimental study on the surface modification of Ni-based superalloy (Inconel 625) reinforced with SiC ceramic particles under electron beam melting. Scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction techniques have been applied to characterize the resulted microstructure. The results revealed growth of novel structures like wire, rod, tubular, pyramid, bamboo and tweezers type morphologies in the modified surface. In addition to that fibrous like structure was also observed. Formation of thin carbon sheet has been found at the regions of decomposed SiC. Electron beam modified surface of Inconel 625 alloy has been hardened twice as compared to the as-received samples. Surface hardening effect may be attributed to both the formation of the novel structures as well as the introduction of Si and C atom in the lattice of Inconel 625 alloy.