Effects of added aluminum chromium slag on the structure and mechanical properties of colored zirconia ceramics

Colored zirconia ceramic samples were prepared via pressureless sintering with yttria-stabilized zirconia as a raw material and aluminum chromium slag (ACS) as an additive. Then, the effects of added ACS (0-15.0 wt%) on the microstructure, phase composition, and mechanical properties of the ceramic were investigated. The addition of ACS changed the apparent color of zirconia ceramics from white to pink, and the color deepened as the ACS content increased. In addition, more pores appeared in the sintered ceramic substrate as the content of ACS increased, and the relative density of samples declined from 97.7% to 91.1% with an increase in ACS content. However, the microhardness and bending strength each reached their maximum values (1887.2 HV and 433.5 MPa, respectively) when the content of ACS was 5.0 wt%. Fracture surface analysis of the samples showed that intergranular fractures were the main features of sintered samples with no added ACS, whereas numerous transgranular fractures occurred in sintered samples to which ACS had been added. The XRD results revealed that the prepared mainly composite ceramics were composed of t-ZrO₂, m-ZrO₂, and chromium-corundum, and the content of the t-ZrO₂ gradually increased as the ACS content increased.