Sol–gel prepared bismuth titanate for high temperature ultrasound transducers

Bismuth titanate (BIT) ceramic was prepared via a sol–gel technique and characterised for use as a high temperature ultrasound sensor. Transducers were prepared as both a pressed ceramic disc and a thick film screen printed on a stainless steel shim. Platinum paste was used as an electrode, and oil bath poling at 120 kV cm−1 and 140 °C was done to align dipoles within the samples. The thermal stability of the BIT with regards to the piezoelectric coefficient was examined. Through-thickness ultrasound measurements were made on aluminium and mild steel blocks, and also on a stainless steel pipe at temperatures of up to 230 °C

High temperature thickness measurements using a bismuth titanate piezoelectric transducer

Bismuth titanate Bi4Ti3O12 was prepared through a sol-gel process, characterised and built as a high temperature ultrasound transducer. Platinum electrodes and wires were used throughout for high temperature stability and Pyrogel 100 used as couplant. The piezoelectric coefficient was found to be stable to 550C. Repeatable thickness measurements were made up to 250°C on aluminium and steel test samples using a pulse-echo technique and the efficiency of the transducer studied under thermal cycling