Microstructure and performance characterization of Co-based diamond composites fabricated via fused deposition molding and sintering.

• Co-based diamond composites were separately fabricated via the FDMS and the powder hot-pressed sintering technology. • There is a certain difference in the overall performance of the two kinds of specimens. • The Co-based samples fabricated by FDMS form a special coating state for diamond particles. • The Co-based samples fabricated by FDMS have defects of high porosity inside the matrix. • The reduction of knife-cut features can represent the improvement of density and holding ability of the FDMS sample. Fused deposition molding and sintering (FDMS) technology has the characteristics of low cost and low damage to diamonds. In order to explore more possibilities of additive manufacturing diamond tools, FDMS technology was considered to manufacture Co-based diamond composites at different temperatures in this paper. Also, specimens of Co-based diamond composites were manufactured under the same sintering process by using the powder hot-pressed sintering technology. And the matrix microstructure and properties of the specimens made by those two different technologies were analyzed and compared. The results show that a lot of porosity defects were developed inside the specimens manufactured by FDMS. This is because of the specific process characteristics of FDMS. Also, the matrix forms a special coating state for diamond particles due to the binder system used in this study, which causes some diamond particles to suffer slight thermal damage. These all will reduce the density and holding ability of the FDMS specimens. However, when the sintering temperature increases from 800 °C to 880 °C, the performance loss of FDMS samples caused by the porosity defects gradually decreases, thereby reducing the performance difference when comparing with the powder hot-pressed sintering specimens. In addition, the matrix structural uniformity of the FDMS specimens is significantly improved during this process, and the fracture feature changes from intergranular fracture to transgranular fracture. But there is still a certain difference in the overall performance of the two kinds of specimens at the optimal sintering temperature. Therefore, the further optimization of FDMS process parameters and binder system is of great significance for the application of FDMS in diamond tools. [ABSTRACT FROM AUTHOR]