A new kind of sintering process, combined sintering process. i.e. vacuum sintering plus hot isolate pressure sintering (HIP), was introduced for producing ultrafine WC-10% Co (mass fraction. so as the follows) cemen...A new kind of sintering process, combined sintering process. i.e. vacuum sintering plus hot isolate pressure sintering (HIP), was introduced for producing ultrafine WC-10% Co (mass fraction. so as the follows) cemented carbides. The effects of some processing parameters on the microstructure and mechanical properties of the obtained cemented carbides were studied. The results show that the rapid shrinkage and the pronounced densification of tile cemented carbides took place during the vacuum sintering stage, which is intinaately correlated with the local liquid sintering occurred during this earl} sintering stage for the high surface activity of ultrafine WC-Co powder. The way of high pressure imposing. isothermal treatment cycle during ac.acuum sintering and HIP sintering stage directly influence the densitication of compacts and the mechanical properties of the produced WC-10%Co cemented carbides.展开更多
The relative density of WC-Co cemented carbides during spark plasma sintering（SPS） was analyzed.Based on the change in displacement of the ram in the SPS system,the relative densities in the sintering process can be...The relative density of WC-Co cemented carbides during spark plasma sintering（SPS） was analyzed.Based on the change in displacement of the ram in the SPS system,the relative densities in the sintering process can be achieved at different temperatures.The results indicated that densification of the samples started at near 900°C,the density rapidly reached its maximum at the increasing temperature stage,in which the temperature was lower than the sintering temperature of 1200°C,and most of the densification took place in the stage.Besides,the theoretical values were consistent with the experimental results.展开更多
Varying the morphology and the structure of γ-phase (Co-base Co-W-C solid solution) by means of altering the cooling rate and the preparing method of liquid sintered WC-Co cemented carbides samples, the mechanism of ...Varying the morphology and the structure of γ-phase (Co-base Co-W-C solid solution) by means of altering the cooling rate and the preparing method of liquid sintered WC-Co cemented carbides samples, the mechanism of fcc→hcp transformation of γ-phase in WC-Co alloy has been explored. The results show that, the cooling rate is an important affecting factor on fcc→hcp transformation of γ-phase and the fcc→hcp transformation is mainly a diffusive type when cooling WC-Co samples above room temperature展开更多
Phase analysis for the coated surface with B 4C and Y 2O 3 of cemented carbide WC-20Co in vacuum-heating was carried out by high-temperature X-ray diffraction from ambient temperature to 1300 ℃. The results show t...Phase analysis for the coated surface with B 4C and Y 2O 3 of cemented carbide WC-20Co in vacuum-heating was carried out by high-temperature X-ray diffraction from ambient temperature to 1300 ℃. The results show that, the high-concentration active boron atoms are released from the boron-supply agent B 4C located on the alloy surface and diffused into the γ-phase, leading to forming the three-element boron-bearing compound W 2Co 21B 6 beside forming boron-bearing compounds on the blank surface. By contrast with boronising only, the element yttrium in boronization broadens the boronising temperature range during vacuum-sintering, catalyzes the decarbonisation decomposition of B 4C and promotes diffusion of active boron atoms into the bulk of WC-Co.展开更多
文摘A new kind of sintering process, combined sintering process. i.e. vacuum sintering plus hot isolate pressure sintering (HIP), was introduced for producing ultrafine WC-10% Co (mass fraction. so as the follows) cemented carbides. The effects of some processing parameters on the microstructure and mechanical properties of the obtained cemented carbides were studied. The results show that the rapid shrinkage and the pronounced densification of tile cemented carbides took place during the vacuum sintering stage, which is intinaately correlated with the local liquid sintering occurred during this earl} sintering stage for the high surface activity of ultrafine WC-Co powder. The way of high pressure imposing. isothermal treatment cycle during ac.acuum sintering and HIP sintering stage directly influence the densitication of compacts and the mechanical properties of the produced WC-10%Co cemented carbides.
文摘The relative density of WC-Co cemented carbides during spark plasma sintering（SPS） was analyzed.Based on the change in displacement of the ram in the SPS system,the relative densities in the sintering process can be achieved at different temperatures.The results indicated that densification of the samples started at near 900°C,the density rapidly reached its maximum at the increasing temperature stage,in which the temperature was lower than the sintering temperature of 1200°C,and most of the densification took place in the stage.Besides,the theoretical values were consistent with the experimental results.
文摘Varying the morphology and the structure of γ-phase (Co-base Co-W-C solid solution) by means of altering the cooling rate and the preparing method of liquid sintered WC-Co cemented carbides samples, the mechanism of fcc→hcp transformation of γ-phase in WC-Co alloy has been explored. The results show that, the cooling rate is an important affecting factor on fcc→hcp transformation of γ-phase and the fcc→hcp transformation is mainly a diffusive type when cooling WC-Co samples above room temperature
文摘Phase analysis for the coated surface with B 4C and Y 2O 3 of cemented carbide WC-20Co in vacuum-heating was carried out by high-temperature X-ray diffraction from ambient temperature to 1300 ℃. The results show that, the high-concentration active boron atoms are released from the boron-supply agent B 4C located on the alloy surface and diffused into the γ-phase, leading to forming the three-element boron-bearing compound W 2Co 21B 6 beside forming boron-bearing compounds on the blank surface. By contrast with boronising only, the element yttrium in boronization broadens the boronising temperature range during vacuum-sintering, catalyzes the decarbonisation decomposition of B 4C and promotes diffusion of active boron atoms into the bulk of WC-Co.
基金National Natural Science Foundation of China(51405326,51575375)Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2014122)
