Abstract

In this study, the continuous alumina fibers reinforced alumina matrix (Al₂O₃/Al₂O₃) composites were fabricated through sol–gel method at a sintering temperature range of 900–1400 °C, and their mechanical properties were analyzed separately. To explore the effects of sintering temperature on mechanical properties of composites, the high temperature properties of fibers and matrix were studied in a comprehensive manner. Our results suggested that the composites fabricated at different temperatures exhibited two different fracture features (ductile fracture and brittle fracture). Besides, the 1100 °C fabricated composites possessed the highest flexural strength of nearly 150 MPa. Al₂O₃ fibers displayed excellent thermal stability, and did not undergo phase transition during the preparation process. However, the grain size of fibers increased dramatically at a sintering temperature of 1200 °C, which led to a significant decrease in the mechanical properties. In the meantime, the surface morphology of fibers became very uneven because of grain coarsening. Due to the phase transition from γ-Al₂O₃ to α-Al₂O₃ at 1200 °C, the elastic modulus and microhardness of matrix increased significantly. The higher sintering temperature not only intensified the matrix but also strengthened the interface bonding, thus making the composites prone to brittle fracture. In conclusion, the optimal temperature of composites preparation should be lower than 1200 °C.

中文翻译：

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烧结温度对氧化铝纤维增强氧化铝基复合材料力学性能的影响

摘要

在这项研究中，在900-1400°C的烧结温度范围内，通过溶胶-凝胶法制备了连续的氧化铝纤维增强氧化铝基复合材料（Al ₂ O ₃ / Al ₂ O ₃），并对其机械性能进行了分析。为了探讨烧结温度对复合材料力学性能的影响，对纤维和基体的高温性能进行了综合研究。我们的结果表明，在不同温度下制造的复合材料表现出两种不同的断裂特征（延性断裂和脆性断裂）。此外，在1100°C的温度下制造的复合材料具有最高的抗弯强度，接近150 MPa。铝₂ O ₃纤维显示出优异的热稳定性，并且在制备过程中没有发生相变。然而，在1200℃的烧结温度下，纤维的晶粒尺寸急剧增加，这导致机械性能的显着降低。同时，由于晶粒粗化，纤维的表面形态变得非常不均匀。由于从相变的γ-Al ₂ ö ₃到的α-Al ₂ ö ₃在1200°C时，基体的弹性模量和显微硬度显着提高。较高的烧结温度不仅增强了基体，而且增强了界面结合，从而使复合材料易于脆性断裂。总之，复合材料制备的最佳温度应低于1200°C。