Study on interfacial diffusion behavior of nano WC-Co-TiC/304 stainless steel composites for micro drill

Abstract

• WC-Co-TiC and 304 stainless steel (SS) for the micro drill were prepared. • The external material is WC-Co-TiC with uniformity and stability. • The internal material is 304 stainless steel with high accuracy under a small size. • The sintering temperature greatly affects WC-Co-TiC / 304SS composite. In this study, the composites of the micro drill with nano WC powder, Co powder, TiC powder (WC:Co:TiC=6:2:2) as outer material and 304 stainless steel as core are compressed at room temperature and sintered at high temperature in a vacuum tube furnace by self-designed mold in the laboratory. The influence of sintering temperature on microstructure, diffusion of elements, hardness and wear resistance are studied by scanning electron microscope, hardness tester, and friction and wear tester. The results show that with the increase of sintering temperature, the number of micropores in WC-Co-TiC/304 stainless steel composites decreases, the mutual diffusion trend of Co and Ni increases, the Fe, Cr and W are slightly diffused, and Ti element has no obvious diffusion. With the increase of sintering temperature, the hardness increases and the wear resistance decreases of WC-Co-TiC/304 stainless steel composites. When the sintering temperature is 1310℃, the hardness of WC-Co-TiC cemented carbide reaches the maximum value of 1394 HV, and the wear trace morphology is the smallest. The maximum depth of the wear trace is about 6841.2 Å, and the corresponding width is about 191.26 μm. Meanwhile, the lowest wear rate is 3.53 × 10 -5 mm 3 ·N -1 ·m -1 .