Chemical stability, microstructure and mechanical behavior of LaPO4-containing ceramics

Abstract The use of LaPO 4 as a weak interface in composites for high temperature applications was investigated using tape-cast laminates and fiber model systems. Three laminates were fabricated with LaPO 4 as one component and Al 2 O 3 , Y 3 Al 5 O 12 or LaAl 11 O 18 as the other. The chemical compatibility between the different components of the laminates, as well as the mechanical responses to flexural deformation and the propagation of indentation cracks, were examined. Two fiber model systems (Al 2 O 3 fiber/LaPO 4 coating/Al 2 O 3 matrix and Y 3 Al 5 O 12 fiber/LaPO 4 coating/Al 2 O 3 matrix) were studied by fiber pushout tests to measure the interfacial shear strengths. The interfacial shear strengths were calculated by the linear and shear-lag approaches for different embedded fiber lengths. The results suggest that Y 3 Al 5 O 12 fiber-reinforced composites with LaPO 4 coatings have potential as high temperature materials in oxidizing environments.

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