Papers by Keyword: Cermet

Abstract: The present study describes the wear and mechanical behaviour of some carbide composites (TiC-base cermets and WC-base hardmetals) in cyclic loading applications (blanking of sheet metal). Adhesive wear as well as fatigue endurance were tested, followed by XRD measurements. The results show that the blanking performance of a carbide composite is dependent on its level of resistance to adhesion wear and fatigue sensitivity. XRD measurement revealed that fatigue damage is preceded by plastic strain in both the ductile binder and the brittle carbide phase.

Abstract: The effect of WC or NbC addition on various properties of Ti(C0.7N0.3)-Ni cermets was investigated. The microstructure of Ti(C0.7N0.3)-xWC-20Ni showed a typical core/rim structure, irrespective of the WC content, whereas the structure of Ti(C0.7N0.3)-xNbC-20Ni was different and was dependent on the NbC content. The hardness (HV) and the fracture toughness (KIC) had a tendency to increase marginally, while the coercive force (HC) and the magnetic saturation (4πσ) decreased gradually with an increase in WC or NbC content in the systems studied. In addition, increasing WC content in Ti(C0.7N0.3)-xWC-20Ni system, decarburization was retarded, while denitrification was accelerated.

Abstract: Injection molding of corrosive super engineering plastics and engineering plastics with various fillers is conducted under severe conditions and causes corrosion and wear problems. Hence, in orde to apply Mo2NiB2 boride base cermets into plastic molding machine parts, the effects of V substitution for Cr on the mechanical properties, corrosion resistance and microstructure of Ni- 5.0B-51.0Mo-(17.5-X)Cr-XV (mass%) model cermets were investigatied. Both transverse rupture strength (TRS) and hardness increased monotonically with increasing V content and reached 2.94GPa and 87.2RA at 10.0%V, respectively. The improvements of TRS and hardness were attributed to microstructural refinement. The excellent corrosion resistance for a molten fluorocarbon resin was obtained up to 5.0%V.

Abstract: Most materials produced today are monolithic structures that are heat treated to perform a particular function. Laser Powder Deposition (LPD) is a technology capable of modifying a metallic structure by adding the appropriate material to perform a desired function (e.g., wear and corrosion resistance). LPD offers a unique fabrication technique that allows the use of soft (tough) materials as base structures. Through LPD a hard material can be applied to the base material with little thermal input (minimal dilution and heat-affected-zone {HAZ}), thus providing the function of a heat treatment or other surface modifications (e.g., carburizing, nitriding, thermal spray and electroplating). Several materials (e.g., Stellite 6 &21, 316 SS, 420 SS, M4, Rex 20, Rex 121, 10V, AeroMet 100, CCW+, IN 625 and IN 718) have been deposited on to carbon steel (4140, 4340, 1566, 1018) substrates to provide various functions for a number of industrial applications. These surface modifications have been evaluated through standard wear testing (ASTM G-65), surface hardness (Rc), micro-hardness (vickers), and optical microscopy. The results from these evaluations will be presented along with several industrial application case studies.

Abstract: Kinik Company pioneered diamond pad conditioners protected by DLC barrier (DiaShield® Coating) back in 1999 (Sung & Lin, US Patent 6,368,198) and there has been no follower since then. Kinik's offered two varieties of DiaShield® Coatings: ultrahard tetrahedral amorphous carbon and superhard hydrogenated DLC. Kink also evaluated Cermet Composite Coating (CCC or C3, patent pending). C3 is unique that the coating composition grades from a metallic (e.g. stainless steel) under layer to a ceramic (e.g. Al2O3 or SiC) exterior. The metallic under layer can form metallurgical bond with metallic matrix on the diamond pad conditioner. The ceramic exterior is both wear and corrosion resistant. The gradational design of C3 coating will assure its strong adherence to the substrate because there is no weak boundary between coating and substrate. By dipping diamond pad conditioners of various designs in acidic solution (e.g. copper cleaning solution) for extended periods of time (e.g. 50 hours) the chemical inertness of various matrix materials are determined with the decreasing ranking as: hydrogenated DLC > C3 coating > tetrahedral amorphous carbon > sintered nichrome > brazed alloy > electroplated nickel.

Abstract: Mo2FeB2 boride base cermets produced by a novel sintering technique, called reaction boronizing sintering through a liquid phase, have excellent mechanical properties and wear and corrosion-resistances. Hence, the cermets are applied to the injection molding die-casting machine parts and so on. Metal injection molding (MIM) is a suitable processing route for the mass production of complex shaped and high performance components. In general, it is difficult for the liquid phase sintered materials to be applied to the injection molding process because significant shrinkage and deformation occur during sintering. In this study, the MIM process was applied in the production of Mo2FeB2 boride base cermets parts. We investigated that the effect of deoxidization and sintering temperature on mechanical properties and deformation of the cermets. As a result, deoxidization temperature of 1323K and sintering temperature of 1518K were suitable. The MIM products of the cermets showed allowable dimensional accuracy and the same mechanical properties as the press-sintered.

Abstract: TiC cermet is widely used for working dies with a high hardness and tool materials. In this research, we attempted to produce submicron sized TiC powders from the ball milled TiH2 and carbon black mixture by thermal treatment. The titanium hydride and carbon composite powders were milled under argon atmosphere for 7 hours at various ball to powder ratios. At the initial stage, an increase in particle size was observed, and graphite phase disappered. The TiC phase of 300nm mean particle size was obtained by milling for 5 hours. As a result, its morphologies were excessively agglomerated. At the heat treating temperature of 500°C, TiH2 phase transformed to Ti completely and the complete TiC of lattice parameter 0.431 nm was formed when the temperature reached 1000°C. Metal matrix composites(MMCs) based on the Fe-TiC system can be synthesized by spark plasma sintering. Specimen formed sintering Fe-TiC powders display a microstructure of uniformly dispersed TiC grain in a continuous metal matrix.

Abstract: TiC particulate reinforced Fe matrix composite compacts with controlled interfacial reaction was processed by spark plasma sintering after mechanical alloying. Milled powders were fabricated for 1-5 hours by spex shaker mill with the ball to powder ratio of 25:2. Metal matrix composites (MMCs) based on the Fe-40%TiC system can be synthesized by spark plasma sintering of the D’AE powders with TiH2-graphite powders under vacuum in the temperature range 1273-1473K for 5-20 min. TiC phase was formed by self combustion reaction with temperature increase. The specimen that was formed by sintering Fe-TiC powders displayed a microstructure of uniformly dispersed TiC grain in a continuous metal matrix. The densifications of the TiC-Fe materials were increased as the heat-treatment holding time increasing. In the same time, relative density and hardness of TiC-Fe sintering materials was increased.

Abstract: Within the project framework the structure and properties was investigated of the cemented carbides, cermets and oxide ceramics using the scanning electron microscope (SEM). The X-ray qualitative microanalysis and surface distribution analysis of elements in the investigated materials were made using the EDS X-ray energy dispersive radiation spectrometer. The roughness measurements of the developed materials were made in two orthogonal directions. The Ra parameter was assumed to be the value describing surface roughness. The microhardness tests using the Vickers method were made on the dynamic ultra microhardness tester. The measurements were made in the „load - unload” mode.

Abstract: The open photoacoustic cell technique (OPC) was carried out in order to measure the thermal diffusivity of hardmetal. Hardmetal is usually processed by the conventional powder technology techniques: mix of WC + Co powders, compacting, and liquid phase sintering A new method to process hardmetal parts is hereby described. Parts of WC-15%wt Co were processed by using high pressure – high temperature sintering. It was used the pressure of 5GPa, temperature of 1350 oC, and time of 2 minutes of sintering. In addition to the thermal diffusivity, heat capacity was considered and the thermal conductivity achieved. Results matched with the values of the literatures where others photoacoustic techniques have been employed. It was achieved a thermal capacity of 3.34J/cm3K, thermal diffusivity of 0.35cm2/s, and thermal conductivity of 116.9W/mK. It reveals that the HPHT processed WC- 15%wtCo hardmetal is able to work as a cutting tool, in the thermal point of view.