The hot vibration durability of ceramic preconverters was examined in this study. Two preconverter designs were investigated. A Generation I design, utilizing 4070g/m2 intumescent mat, was examined at 900°C/75g. A Generation II design, possessing 6200g/m2 intumescent mat and insulated end cones, was evaluated at 1050°C/75g. Three consecutive Generation I samples passed 900°C/75g exposures of 100 hours. Three Generation II preconverters tested at 1050°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 I samples possessed an average residual shear strength of 450kPa. Generation II samples, tested at 1050°C/75g, retained an average mat shear strength of 61kPa. A minimum calculated shear strength of 15kPa is required.
An alternative thermal aging technique was applied to new sets of Generation I and II 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 results 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.