The Research& Development Situation for Ultra-fine and Nanometer cemented Carbide Materials(2)
Mr.F Friedrichs from Konrad Friedrichs in Germany though the cutting tools for bearing also with the trend to be changed to solid cemented carbide from high speed steel ,the new grade as K44(WC 12%Co ,added Cr3C2 and VC grain growth inhibitor) has became the material of standard and customized mills .On the other hand ,Mr.F Friedrichs convinced that the K series cemented carbide with grain size from 1.5~0.2um and 6%~12% cobalt content will take 90% of the market, meanwhile there is a very quite broad research and development space for the carbide and cemented carbide producing process .
Mr.A Bock and Mr B Zeiler from Austria discussed on the CRC technique (calcination-restoration-carbination) for producing submicron cemented carbide ,and pointed out that it is very helpful to control the grain growth to add Cr before calcination,this is because the additive could be dispersed evenly in the carbide grain boundary .Mr.W Grogger and its colleague Tizit worked together to analysis the additive chemical content and dispersion in submicron cemented carbide with advanced electrical microscopes, who found only VC film without Cr existing in the WC grain boundaries of cemented carbide added with chrome and vanadium elements
Mr.K Kitamura from Tokyo University and its colleagues discussed new type cemented carbide made of complex structure Co, WC composition,this kind of tungsten carbide with plate-type structure and anisotropy, meanwhile its fracture toughness value is higher 10%~15% than usual ones ,but with the same hardness .
