Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (26권2호 87-107)

Production of the ultra fine-composite powders of WC-Co and WC-Ni

초미립의 탄화 텅스텐-코발트와 탄화 텅스텐-니켈 복합분말의 제조

김병재;윤병하;
;;

경북대학교 공과대학 금속공학과;
경북대학교 공과대학 금속공학과;

Abstract

The grain size of the final products of WC-Co and WC-Ni composite powders is dependent on the size of the starting material and the conditions employed for the reduction and carburization. APT-Co and -Ni com-plex salts were prepared by the substitution reaction between ammonium ions in APT and the metal ions in Co(NO3)2 and Ni(NO3)2 solutions of different concentrations(0.1 to 0.7M) at $50^{circ}C$ and the grain sizes of the com-plex salts was $0.54~0.76mu extrm{m}$. The complex which calcined the complex salts at $700^{circ}$~80$0^{circ}C$ for 60min. were 0.2~0.5$mu extrm{m}$. W-Co($5.92^{circ}C$) and -Ni(6.95%) powders which reduced the complex oxides with H2d atmo-sphere(flow rate;600cc/min.) at $700^{circ}$~$800^{circ}C$ for 60min. were $0.5~0.6mu extrm{m}$. The mean grain sizes of WC-Co and WC-Ni composite powders which carburized both complex metals of W-Co and W-Ni at $800^{circ}C$ for 60min. were $0.5~0.6mu extrm{m}$, and take place the coarsening of the grain above $800^{circ}C$ and the optmium ratio of C3H8 and H2 was 0.2 for the control of the free carbon. The effect of Co contents on the particle sizes decreased from 0.4 to $0.25mu extrm{m}$ with increasing the content from 2.0 to 7.6w%. The activation energies on the reductions of oxides and the formations of carbides were as follows ; W-Co : Q = 8.7 kcal/mole, W-Ni : Q = 8.1 kcal/mole, WC-Co pow-der : Q = 17.8 kcal/mole, WC-Ni powder : Q = 16.6 kcal/mole.

Keywords