Study Of Ultra-fine Cemented Carbide Grain Growth Restrain Mechanism And Heat Treatment Technics

In the 21th century, electron products such as mobile and notebook PC have more and more strong function but smaller and smaller in the shape size. Which made circuit of PCB integrationlize more indensity than ever. the lead hole size of PCB is 0.80mm→0.50mm→0.40mm→0.30mm→0.25mm→0.20mm→0.10mm→0.05mm. Which demand machining tools not only have enough hardness to ensure superexcellence wearable, bu also have suffice TRS to assure it will not break in the work. Since the appear of Super fine cemented ceramic with It's higher hardness and higher TRS, the expectation to the machining tools will come into truth in the material aspect. These phenomena have arosed abroad attention all the world. More and more study on the super-fine ceramic at domestic and overseas become profundity. While, as the technology close off of world-class company, there are few report on the technics of super-fine cemented ceramicIn This paper, we use imported Ultra-fine WC powders producted by American OMG company and Ultra-fine cobalt powders producted by NanJing HanRui Co. Ltd as crude materials, use vacuum-dryness and low-pressure sinter as process method, and use HREM,SEM,X—ray,EDS,DSC as analyse measure, discuss the effect on super-fine cemented ceramic capability of inhabitor particularly, discuss the advantage and disadvantage of VC Cr₃C₂, analyse the process of WC crystal grain growth and the working mechanism of inhabitor in-depth, study on the property-heighten of heat treatment to super-fine ceramic systemly. The results shows that both VC and Cr₃C₂ can inhabite WC crystal grow up, the hardness and Hc of alloy will increase while TRS decrease. VC can inhabite WC crystal particle grow up more effectively whlile Cr₃C₂ in favor of TRS, so the mix doped inhibitors of VC and Cr₃C₂ in light of appropriate proportion will obtain more excellent synthetical performance. no matter what kind of inhabitor, the append count must be appropriate, or else will do harm to property of ultra-fine cemented carbides.Study by HREM indicate that VC will make WC crystal particle become smaller and uniformity, while the shape will become abnormity, the felt phase will distributing not uniformity. Cr₃C₂ can make WC crysta grain'shape standardization and felt phase distributing abroadly, but there are some larger grains. Analysed by EDS, we found that VC and Cr₃C₂ both deposited in felt phase, which inhabite the WC crystal grain growth by slow the grain solvedeposit. between the two kind of inhabitor, VC has apparently restrain effect but bring about the strength decrease. The complex of Cr₃C₂ and VC have excellent synthesis effect.Heat treatment experiment shows that quench on super-cemented carbide will enhance 13.6 percent on TRS while the hardness remain. After temper treatment subsequently, the alloy will improve the TRS by 10.5percent, and then the hardness will ameliorate slightly. observed by SEM shows that, the edges and corners of WC grain will disappear, felt phase volume will strengthen, rupture method will change after heat treatment, We analyze ingredient transformation in the felt phase by XRD, data shows that content ofε—Co at will decrease whileα—Co increase, that is the main renson cause TRS strengthen. At lase, we use DSC find that the temperature of phase change variety with Co content, These results in our research have guidance meaning in industry production.