Papers by Keyword: Ti(c,n)-based Cermet

Abstract: Four Ti (C,N)-based cermets with Cr₃C₂ content of 0.3%, 0.6%, 0.9% and 1.2 % in mass ratio were sintered in vacuum at 1430oC, 1450oC, 1465oC and 1480oC. The mechanical properties of the specimens were determinted and microstructures were observed using the scanning electron microscope (SEM) to study the effect of Cr₃C₂ content on mechanical properties and microstructure. The results show that the four Ti (C,N)-based cermets sintered at 1465oC have the best overall mechanical properties; and among them, the cermet with 0.6% Cr₃C₂ has the best overall mechanical properties, i.e. transverse rupture strength (TRS) 1967MPa, hardness 1556HV and fracture toughness (K_IC) 9.5MPa.m^1/2. With the increase of Cr₃C₂ content, the black core volume fraction firstly increases and then decreases, the white core decreases in a progressive and continuous manner, the rim phase firstly increases and then decreases, the binder phase firstly decreases and then increases.

Abstract: Ti(C,N)-based cermets with three carbon contents are prepared by sintering in vacuum. The effects of carbon content on the microstructure, mechanical properties and wear resistance of Ti(C,N)-based cermets were investigated. The results show that the grains refine gradually and the hard phase core becomes smaller when the carbon contents increases. The mechanical properties closely relates to the carbon content. With the increase of carbon content, the furrows created by grains cutting are getting narrower and more intensive. When the carbon content reaches 0.8%, a large quantity of wear debris bonding blocks are attached on the wearing surface. In this condition, the Ti(C,N)-based cermets are of the minimum wear weight loss and the best comprehensive mechanical property.

Abstract: In this study, titanium carbonitride (Ti(C,N)) based cermets were prepared by submicron particles, sintered in a vacuum and hot-pressing furnace. And the effect of different ball-milling time (36 h, 48 h, 60 h and 72 h, respectively, mostly aimed for mixing) on the mechanical properties of Ti(C,N)-based cermets, including transverse rupture strength (TRS), Vickers hardness (HV20), fracture toughness (K_IC) and microstructure were investigated. The results showed that the TRS, hardness and fracture toughness were all improved with an increase in ball-milling time (not more than 60 h). Scanning electron microscopy (SEM) investigations on the microstructure of cermets with different ball-milling time revealed that the compound powders were not very well-distributed as a whole and there were coarse hard phase grains, but the microstructure was very homogeneous in parts, and the microstructure of cermets with a ball-milling time of 60 h is relatively more homogeneous. So a refinement to Ti(C,N) raw particles is needed in later studies.

Abstract: Element Mo plays a significant role in Ti(C,N)-based cermets. In this work, mixing was carried out in water and cermets with high mechanical properties were fabricated. The effect of Mo₂C content on microstructure and composition was investigated by field emission scanning electron microscope (FSEM) and energy dispersive spectrometer (EDS). Results showed that microstructure becomes uniformly distributed, binder distribution becomes symmetrical and the particle size becomes small with increase of Mo₂C content. The volume fraction of (outer + inner) rim structure increases, the volume fractions of core structure and binder phase decrease instead. It was found that Mo₂C content in raw material affects compositions in phases. With the level of Mo₂C content rising, the concentration of element Mo in rim structure increases, the concentration of element Ti in binder decreases.

Abstract: α-Al2O3 and α-Al2O3/TiN multilayer films were prepared on Ti(C,N)-based cermet substrate by laser chemical vapor deposition.α-Al2O3 and NaCl-type TiN films were prepared at Tdep = 1148 K. α-Al2O3/TiN multilayer film showed dense structure of cross section, and its surface morphology consisted of aggregated spherical grains. The adhesion of α-Al2O3/TiN multilayer film prepared on Ti(C,N)-based cermet was higher as compared with α-Al2O3 film directly prepared on the cermet.

Abstract: Ti(C, N)-based cermet and functionally gradient Ti(C, N)-based cermet were prepared by vacuum sintering and post surface heat-treatment in nitrogen, respectively. Tribological behaviors of obtained cermets were comparatively studied. Dry sliding wear and cutting test were conducted against quenched medium carbon steel. It was found that a graded structure formed and the surface hardness of functionally gradient Ti(C, N)-based cermet was improved. Friction coefficients of both cermets decreased with the increase of the sliding speed. The friction coefficient of Ti(C, N)-based cermet was lower than that of functionally gradient Ti(C, N)-based cermet at the conditions of higher sliding speed and higher load. The cutting test demonstrated that Ti(C, N)-based cermet exhibited better cutting performance and higher wear resistance than the cemented carbide YT15, cermet TN20 and functionally gradient Ti(C, N)-based cermet, while the functionally gradient Ti(C, N)-based cermet exhibited a similar performance as YT15 and TN20.

Abstract: The composition, microstructures and properties of the Ti(CN) based cermets have been characterized by using SEM/BSE and energy spectrometer. Results shows that the carbon content of the cermets through N2 and Ar sintering was lower by 0.5% than vacuum sintering and the nitrogen content of the cermets through N2 sintering was higher by 20~25% than the Ar and vacuum atmosphere sintering. When sintered in Ar or N2, the balance between the carbon and nitrogen in the cermets was broken to form a surface defects, which would result in poor properties. The structure of vacuum sintering is more uniform and the properties are better.

Abstract: In this paper, the TiCN-based cermets were fabricated with ultrafine TiCN, metal binders and carbide additives. Different content of C and Al were separately added to eliminate the oxygen contamination. The composition of the mixture was TiCN-10Mo-20WC- 20Ni-xC/Al. Effect of the C and Al addition on microstructure and mechanical properties was investigated. Results indicated that cermets with carbon addition had higher relative density and more homogenous microstructure while the Al addition had the opposite effect. Proper addition of carbon improved the mechanical properties.

Abstract: In this paper, the Ti(CN)-based cermets were fabricated with ultrafine Ti(CN) powders, additives WC, Cr2C3 and Mo, metal binder Ni by vacuum sintering and HIP treatment. The composition of the mixture was Ti(CN)-10Mo-20WC-xCr2C3-20Ni. Effect of Cr2C3 addition on microstructure and mechanical properties was investigated. Results indicated that with increasing Cr2C3 content, the relative densities after vacuum sintering decreased and the grain sizes of cermets increased. Cr2C3 addition to the cermets improved the hardness but had some negative effect on the performance of bending strength.

Abstract: In this paper, the Ti(C,N)-based cermets were fabricated with ultrafine Ti(C,N) powders and metal binders Mo and Ni, in which the ratio of Mo to Ni was 1:1 and total metal content ranged from 10wt% to 20wt%. The specimens were first CIP and pressureless sintered at various temperatures ranged from 1450°C to 1600°C and then treated at 1350°C for 20mins by HIP at the pressure of 140MPa. Results revealed that Post-HIP treatment could dramatically improve the density of specimens if their densities after pressureless sintering could reach the required standard. At the same sintering temperature, the grains became finer with increasing metal contents. The grain sizes increased dramatically with increasing sintering temperature from 1550°C to 1600°C. Compared to those obtained by hot pressing, the cermets obtained by pressureless-HIP sintering had better mechanical properties.