碳化硅晶须补强氧化铝复合材料的制备及其力学性能

本论文利用商用γ-Al₂O₃粉体和上海硅酸盐所制备的碳化硅晶须，通过热压工艺来制备碳化硅晶须补强氧化铝复合材料．当晶须含量为30vol％时，室温下复合材料的抗弯强度为812±38MPa，断裂韧性为8．8±0．1MPa·m^1／2；在1200℃、Ar气氛下，分别为560±61MPa和6．1±0．4MPam^1／2．在氮气氛下，由于晶须的损伤易导致材料的力学性能下降．添加剂可降低复合材料的烧结温度，但不利于其力学性能．显微结构观察发现，不同温度下，AS复合材料的增韧机理有变化．

Preparation and Mechanical Properties of SiC Whisker-Reinforced Alumina

SiC whisker reinforced alumina composites were fabricated by hot-pressing from the commercial γ-Al₂O₃ and SiC whisker made in Shanghai Institute of Ceramics. We obtained some samples with 30vol% SiCw hot-pressed at 1800℃ in Ar atmosphere having the flexure strength of 812±38MPa and fracture toughness of 8.8±0.1MPa·m^1/2 at room temperature; 560±61MPa and 6.1±0.4MPa at 1200℃ respectively. The small amount of additions accelerated densification but reduced the mechanical properties. In N₂ atmosphere, SiC whisker would be injured and the composites mechanical properties degraded. Moreover, the microstructural observations indicated that the toughening mechanism of AS composites is different from whiskers pull-out and matrix’s cleavage fracture at room temperature to whiskers/matrix interface debonding and matrix’s intergranual fracture at high temperature.