Abstract: A layer selected from a group comprising: molybdenum, tantalum, tungsten, osmium, rhenium, ruthenium and an alloy of two or more thereof on the under surface of an electrical contact acts as a barrier to copper diffusion from the braze material into the contact structure. A thin nickel layer on the barrier facilitates the brazing of the barrier coated contact surface to the copper electrodes.

Abstract: An easily replaceable acoustic transducer assembly is provided for usage in high temperature applications. The improved structure permits efficient acoustical coupling between the component parts of the tranducer assembly, and is more readily reproducible in sensitivity and frequency response. A generally tubular high temperature resistant metal enclosure is provided with an acoustical window which is coupled to the piezoelectric transducer element. The piezoelectric element is acoustically coupled to a damping block member. Acoustical coupling between the active elements of the transducer assembly is had from a compressive means integral within the enclosure member.