Quantitative investigation of thermal evolution and graphitisation of diamond abrasives in powder bed fusion-laser beam of metal-matrix diamond composites
Qingyuan Ma, Yingbo Peng, Yongqian Chen, Yuan Gao, Shanghua Zhang, Xiwang Wu, Jun Zheng, Hong Wu, Lan Huang, Yong Liu, Wei Zhang
Abstract
Preventing the thermal damage of diamond abrasives is the major challenge of diamond composites in the field of super-hard tools by laser additive manufacturing. In the presented work, we established a quantitative framework to accurately evaluate the thermal damage behaviour and the relevant microstructure-performance characteristics, by using CuSn10-diamond composite by powder bed fusion-laser beam (PBF-LB). By simulating the thermal history of diamond in the molten pool and microstructure characterisation, the critical temperature of 1491.6°C of diamond graphitisation was obtained. Below the critical temperature, the composite with no diamond-graphitisation exhibited abrasive wear and wear loss rate below 0.01%. The increasing temperature led to the aggravation of graphitisation, which ID: IG value changed from 2.00 to 0.57 with the temperature increasing from 1491.6°C to 1896.1°C, resulting in wear mechanism changing from adhesive wear to three-body abrasion, with the wear loss rate from 0.01% to 0.73%. Integrating the results of simulation, microstructures and wear properties, the graphitisation threshold of diamond in PBF-LB was revealed and the quantitative relationship of ‘PBF-LB parameters - Temperature - Graphitisation degree - Wear resistance’ of the metal-matrix diamond composites was established.