Sol-gel composite materials for continuous monitoring at 600°C

Ultrasonic testing is mainly used because it can detect internal defects however, on-line monitoring for thermal power generation is difficult due to high temperatures such as 550°C. Sol-gel composite ultrasonic transducers can operate high temperatures and in the recent study, Mn-doped CaBi₄Ti₄O₁₅(CBT)/Pb(Zr,Ti)O₃(PZT) sol-gel composites has been developed for nondestructive testing above 500°C to improve sensitivity and signal-to-noise ratio (SNR) at high temperatures. Mn-domped CBT/PZT demonstrated comparable performance with Bi₄Ti₃O₁₂(BiT)/PZT at 500°C and it still showed ultrasonic response with reasonable SNR at 600°C even though BiT/PZT lost its ultrasonic response. From long-term monitoring test results to evaluate on-line monitoring capability, Mn-doped CBT/PZT was more suitable than BiT/PZT for long-term monitoring at 600°C.