Novel Platelet Composites for Improved Mechanical Behavior

小行星9616668 近年来，片状增强陶瓷复合材料已成为许多结构应用中晶须和纤维增强材料的可行替代品。 人们认识到，增强相和基体/片晶界面的某些特性将有利于改善韧性行为，例如，血小板/基质界面易于脱粘，血小板体积分数高，但详细的系统研究有限。 基于最近在Lehigh进行的工作，据信由涂覆有六铝酸钙（CA 6）的氧化铝片晶组成的新型复合系统具有超过常规片晶复合材料的性能的潜力。 CA 6具有几个特性，使其非常适合所提出的应用。 这些包括采用外延关系，使得CA 6的弱基底解理面平行于（0001）α-氧化铝片晶面对齐，有利于脱粘的热膨胀系数值，以及与氧化铝的热力学稳定性。 提出了块状复合材料和界面结构的力学表征。 使用TEM对脱粘界面进行高分辨率研究，以补充加工和机械测试。该方案的目标是多重的。 一个目的是确定优化机械性能的复合材料系统的加工和微观结构参数。然而，在一个更基本的水平上，所提出的程序将使界面结构，韧性和强度的界面之间的直接相关性，和散装复合材料的机械行为。 近年来，片状增强陶瓷复合材料已成为许多结构应用中晶须和纤维增强材料的可行替代品。 人们认识到，增强相和基体/片晶界面的某些特征将有利于改善韧性行为，但详细的系统研究有限。 基于最近在Lehigh进行的工作，据信由涂覆有六铝酸钙（CA 6）的氧化铝片晶组成的新型复合系统具有超过常规片晶复合材料的性能的潜力。 该方案的目标是多重的。 一个目的是确定优化机械性能的复合材料系统的加工和微观结构参数。 然而，在一个更基本的水平上，所提出的程序将使界面结构，韧性和强度的界面之间的直接相关性，和散装复合材料的机械行为。 ***

9616668 Chan In recent years, platelet reinforced ceramic composites have emerged as viable alternatives to whisker and fiber reinforced materials for many structural applications. It is recognized that there are certain characteristics of the reinforcement phase and the matrix/platelet interface which will favor improved toughness behavior, e.g., ease of debonding at the platelet/matrix interface, high platelet volume fraction, however detailed systematic study has been limited. Based on recent work carried out at Lehigh, it is believed that a novel composite system consisting of alumina platelets coated with calcium hexaluminate (CA6) has the potential to surpass the properties of conventional platelet composites. CA6 exhibits several characteristics which make it exceptionally well-suited for the proposed application. These include the adoption of an epitaxial relationship such that the weak basal cleavage planes of CA6 align parallel to the (0001) a-alumina platelet faces, values of thermal coefficients of expansion which favor debonding, and thermodynamic stability with alumina. Mechanical characterization of both the bulk composites and the interface structures is proposed. The processing and mechanical testing will be complemented by high resolution study of debonded interfaces using TEM. The goals of the program are several-fold. One aim will be to determine the processing and microstructural parameters of the composite system which optimize the mechanical properties. On a more fundamental level, however, the proposed program will enable the direct correlation between interfacial structure, the toughness, and strength of the interface, and the mechanical behavior of the bulk composite. %%%% In recent years, platelet reinforced ceramic composites have emerged as viable alternatives to whisker and fiber reinforced materials for many structural applications. It is recognized that there are certain characteristics of the reinforcement phase and the matrix/platelet interface which will favor improved toughness behavior, however detailed systematic study has been limited. Based on recent work carried out at Lehigh, it is believed that a novel composite system consisting of alumina platelets coated with calcium hexaluminate (CA6) has the potential to surpass the properties of conventional platelet composites. The goals of the program are several-fold. One aim will be to determine the processing and microstructural parameters of the composite system which optimize the mechanical properties. On a more fundamental level, however, the proposed program will enable the direct correlation between interfacial structure, the toughness, and strength of the interface, and the mechanical behavior of the bulk composite. ***