Quantification of Ceramic Preconverter Hot Vibration Durability

The hot vibration durability of ceramic preconverters was examined in this study. Two preconverter designs were investigated. A Generation 1 design, utilizing 4,070 g/m{sup 2} intumescent mat, was examined at 900 C/75g. A Generation 2 design, possessing 6,200 g/m{sup 2} intumescent mat and insulated end cones, was evaluated at 1,050 C/75g. Three consecutive Generation 1 samples passed 900 C/75g exposures of 100 hours. Three Generation 2 preconverters tested at 1,050 C/75g similarly passed 100 hour exposures. The residual shear strength of each preconverter tested in hot vibration was measured to quantify durability. Hot push shear evaluations were performed to obtain the residual shear strength. Following 900 C/75g hot vibration exposures, the Generation 1 samples possessed an average residual shear strength of 450 kPa. Generation 2 samples, tested at 1,050 C/75g retained an average mat shear strength of 61 kPa. A minimum calculated shear strength of 15 kPa is required. An alternative thermal aging technique was applied to new sets of Generation 1 and 2 specimens. These samples did not experience mechanical vibration. Results of hot push shear measurements on these components indicated that the residual shear strengths were similar to those obtained for specimens exposed to hot vibration. These resultsmore » indicated that the thermal conditions were the primary cause of Mat deterioration in hot vibration. The supplemental test methods investigated in this study represent an economical and quantitative alternative to hot vibration testing.« less