CHARACTERIZATION OF YTTRIUM PHOSPHATE AND A YTTRIUM PHOSPHATE YTTRIUMALUMINATE LAMINATE

Single-phase yttrium phosphate (YPO4) and a YPO4/ yttrium aluminate (Y 3Al5O12) laminate mere studied. Young's modulus, Poisson's ratio, Vick ers hardness, and coefficient of thermal expansion of YPO4 sintered bo dies were measured, YPO4 and Y3Al5O12 are chemically compatible and mo rphologically stable up to at least 1600 degrees C. The fracture behav ior mas studied by four-point flexural testing on bars with ground or notched tensile surfaces, and by the indentation method. Noncatastroph ic fracture could be seen in these specimens, In flexural testing, cra cks could be bridged by YPO4 layers, followed by some interfacial debo nding, Indentation responses also consistently showed some interfacial delamination in the YPO4/Y3Al5O12 laminate.