Field Deployable Spray-on Ultrasonic Coatings for High-Temperature Applications

Field testing of structures at high-temperature is a challenge as commercial transducer are not rated for such high-temperatures. There is an increased interest in the use of film transducers for the testing of materials. With the diminishing size in everyday objects, the systems incorporated to monitor them also need to decrease in size. The complexity of the model is an added reason for the rise of this technology. Film coatings have served various purposes in the field of NDE. Previous work has been performed using sol-gel, potato starch and PZT as the piezoelectric material, but due to their individual disadvantages, other inorganic materials were studied. This transducer consists of a piezoceramic film composed of Bismuth Titanate and a high-temperature inorganic binding agent, Ceramabind 830. A thick film forms on the substrate which is then poled in an electric field to impart piezoelectricity in the film. Pulse-echo measurements for signal voltage over a certain period of time are made to validate its workability. The films were tested to elevated temperatures and a guided-wave system is currently being studied to provide in-situ monitoring for pipes and rod like structures.