Microstructure and electrical properties of aluminum oxide-reinforced 3 mol% yttria-stabilized tetragonal zirconia polycrystals/TiSi2 composites by vacuum sintering

Abstract

3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP)/TiSi₂ composites reinforced with aluminum oxide (Al₂O₃) were synthesized by vacuum sintering. This case investigated the effects of Al₂O₃ content ranging from 0 to 10 wt.% on the microstructure, mechanical, and electrical properties of 3Y-TP/TiSi₂ composites. According to the results, the addition of Al₂O₃ hindered the densification of the material, resulting in a deterioration in the relative density of composites. On the contrary, the hardness, flexural strength, and average grain size of the conductive phase increased. The maximum value of hardness and flexural strength was 88.70 HRA with 7.5 wt.% Al₂O₃ and 635.45 MPa with 10 wt.% Al₂O₃, respectively. In addition, the addition of Al₂O₃ increases the ratio of grain size between the conductive and insulating phases in composites, leading to a decrease in the percolation threshold and a reduction in resistivity from 4.00 to 1.60 × 10⁻³ Ω·cm with increasing Al₂O₃ content. In conclusion, Al₂O₃ reinforced the comprehensive mechanical properties and optimized the electrical properties of composites by changing the microstructure of the material.