Optimal Process Parameters for 3Y―TZP/TiN Conductive Polycrystal by Taguchi Method

For the manufacturing of 3mol% Yttria― tetragonal Zirconia polycrystal (3Y―TZP) with 30wt% of Titanium Nitride (TiN) (3Y―TZP/TiN) powders, Taguchi method was used to selected the process parameters including sintering step variation, crushing time of TiN powder, the first step sintering duration and second step sintering temperature to be the controlling factors. The characterization features of sintered samples such as fracture toughness, flexural strength, hardness, relative density and electric resistance were explored through L9 orthogonal array. By analysis of variance (ANOVA), the optimal parameter settings for each response factor were obtained and tested through confirmation experiments. The results indicate that the optimal process parameters contain 8 h crushing time of TiN powder, two ― steps sintering processes including the 1450 emperature with no duration for the first step and 1150 emperature and 20 h duration for the second step, and the average flexural strength of 736.75 MPa and fracture toughness of 7.545MPa·m1/2 are obtained. In addition, the degree of the process parameter effects on the sintered samples is found in the series of the sintering duration of the first step, sintering step variation, size of TiN particles and the sintering temperature of the second step. Meanwhile, fracture toughness depends significantly on the ratio of tetragonal phase to monoclinic phase and attends to be 9.275 MPa·m1/2 when the ratio is getting to the maximum. The average electric resistance for 3Y― TZP÷TiN is measured to be 3.26 mΩ·cm, these samples can be electric―discharge machined.