Dependence of Density, Hardness, Strength, and Dimensions of WC–15 Co Hard Alloy Samples on the Plasticizer Content in Workpieces Obtained Using a Plastic Mold Made by 3D Printing

Abstract

The influence of plasticizer content (rubber) on the density, microstructure, and properties of WC–15 Co alloy samples obtained using a plastic mold made with the help of additive technologies has been investigated. It has been experimentally found that, in molds made of polylactide with a strength of 70 MPa, the workpieces can be pressed at a pressure of up to 120 MPa. An increase in plasticizer concentration from 1 to 4 wt % leads to an increase in the density of workpieces from 61 to 90% after pressing and a decrease in the density of samples from 99.5 to 99.3% after sintering. This is 0.3–0.6% less than the density of products obtained after pressing in a steel mold at a pressure of 210 MPa. Deviations in density do not affect the microstructure and hardness of the obtained samples, which is 1140–1170 HV. Owing to the lower density and the presence of individual large pores up to 100 μm in length, the strength of products obtained using a plastic mold (1550–1980 MPa) turned out to be lower than the strength of products obtained using a steel mold (2230–2430 MPa). However, the density of blanks and the resulting hard-alloy samples turned out to be significantly higher than the density and hardness of samples obtained using existing additive technologies.