Wear Resistance Improvement of Copper Alloys Using a Thermochemically Obtained Zinc-Rich Coating

Abstract

It has been developed a thermochemical process that has been applied on copper alloys: brass and bronze, using pure zinc powder, obtaining a zinc-rich wear protective coating. The layers obtained by a diffusion process, on brass (alloy C36000) and bronze specimens (alloy SAE 62), were characterized using a scanning electron microscope, EDAX microanalysis, Vickers microhardness, X-Ray diffraction analysis, and sliding wear test. The chemical analysis showed a layer composition of 62 % Zn and 38 % Cu, on average. The microhardness for thermochemical treated brass was 496HV and 598HV for bronze; thus, a microhardness increase for brass is 468% and 532% for bronze. It was made an X-Ray diffraction analysis, confirming the results obtained with the chemical analysis and crystalline structure for coating. It showed the presence of Cu64Zn36 and Cu5Zn8 phases. The wear tests demonstrated that treated specimens show better wear resistance than non-protected specimens.