Property-Porosity Relationships for Polymer-Impregnated Superconducting Ceramic Composite

A thermoplastic polymer, poly(methyl methacrylate) (PMMA), was used to improve the flexural properties of the high-temperature superconducting ceramic (YBa₂Cu₃O_7-δ). Ceramic specimens with different porosities were prepared by dry compacting 12.5-mm-diameter disk specimens at various uniaxial pressures. Density-pressure relationships have been developed for before- and after-sintering conditions. The PMMA polymer was impregnated into the porous ceramic at room temperature. The mechanical properties were evaluated by concentrically loading simply supported disk specimens. The load-displacement responses were analyzed using the finite-element method. Impregnation of PMMA polymer at room temperature increased the flexural strength and modulus of the superconducting ceramic without affecting its electrical propeties. The flexural properties depended on the porosity of the ceramics, and, hence, linear and nonlinear property-porosity relationships have been used to characterize the behavior of superconducting ceramic with and without the polymer.