Influence of tin on the structure and hardness of metallic binders of diamond tools fabricated by composition brazing

Resumo

The influence of the tin content on the structure and hardness of Sn–Cu–Co and Sn–Cu–Co–W alloys, which are applied as binders of diamond abrasive tools, is investigated. The binders are prepared by compositional brazing: powdered components are mixed with an organic binder and deposited on a steel base. Sintering is performed at 820–1100°C. The structure of metallic binders is investigated by X-ray diffractometry and electron probe microanalysis. In addition, the microhardness of structural components and macrohardness of binders are measured. It is established that the hardness of metallic binders linearly increases with an increase in the tin content due to an increase in the amount of solid intermetallic phases in their structure. The optimal tin content, which provides high hardness (96–98 HRB) and the absence of lowmelting high-tin intermetallic compounds in their structure, is determined for Sn–Cu–Co–W binders.