Preparation and properties of in-situ mullite whiskers reinforced aluminum chromium phosphate wave-transparent ceramics

摘要

In-situ mullite whisker reinforced aluminum chromium phosphate wave-transparent ceramics were designed and prepared. The phase transformation, microstructure, mechanical and electrical properties of the ceramics were investigated, and the mechanisms of in-situ growth and toughening were discussed. Results indicated that the in-situ growth of mullite whisker significantly improved the mechanical properties of the matrix, especially the high temperature flexural strength. The room temperature flexural strength, 1000°Cflexural strength and fracture toughness of the ceramics were 135.60 MPa, 121.71 MPa and 4.52 MPam~(1/2). After sintering at 1500°C , the optimum properties of ε'_r, tanδ and microwave trans-mittance at region 8-12 GHz were <3.6, <0.03 and>80%, respectively. The sinterability of ACP matrix was improved by the in-situ process of high mullization above 1450°C. Using ACP binder as the raw material can avoid the phase transformation from B-AlPO_4 to T-AlPO_4. The synthesized mullite whiskers played a role in toughening by whiskers fracture, crack deflection and whisker pulling out.