Control of interfacial properties through fiber coatings: Monazite coatings in oxide-oxide composites

Fiber pushout tests were used to quantify the effects of fiber coating thickness on the mechanical properties of two model composite systems: a monazite-coated (LaPO₄-coated) alumina (al₂O₃) fiber in an al₂O₃ matrix and a LaPO₄-coated yttrium aluminum garnet (YAG) fiber in an Al₂O₃ matrix. Interface properties were quantified using the Liang and Hutchinson (LH) pushout model and mechanistically rationalized by considering the change in residual thermal stresses with changes in the coating thickness. Measures of the pure Mode II interfacial fracture energy, the coefficient of friction, and a radial clamping pressure are extracted by filling the LH equations to the experimental results. Using the approach that has been developed herein, a methodology is available for measuring the interfacial properties, predicting the effect of coating thickness and selecting the coating thickness to alter the interfacial properties.