THE EFFECT OF SUBSTRATE-TEMPERATURE ON THE THERMAL-DIFFUSIVITY AND BONDING CHARACTERISTICS OF PLASMA-SPRAYED BERYLLIUM

Plasma spraying is under investigation as a method for in-situ repair of damaged beryllium and tungsten plasma facing surfaces for the Inter national Thermonuclear Experimental Reactor (ITER), the next generatio n magnetic fusion energy device, and is also being considered as a pot ential fabrication method for beryllium and tungsten plasma-facing com ponents for the first wall of ITER. Investigators at Los Alamos Nation al Laboratory's Beryllium Atomization and Thermal Spray Facility have concentrated on investigating the structure-property relationship betw een the as-deposited microstructures of plasma sprayed beryllium coati ngs and the resulting thermal properties of the coatings. In this stud y, the effect of substrate temperature on the resulting thermal diffus ivity of the beryllium coatings and the thermal diffusivity at the coa ting/beryllium substrate interface was investigated. Results have show n that increases in the beryllium substrate temperature can improve th e thermal diffusivity of the beryllium coatings. Results also indicate that the thermal resistance at the interface between the beryllium co ating and the beryllium substrate were minimal and showed little depen dence on the substrate temperature. The effective bond strength and fa ilure characteristics of plasma spray beryllium on beryllium surfaces were predominately dominated by mechanical interlocking at low substra te temperatures and increased metallurgical bonding at higher substrat e temperatures. (C) 1997 Elsevier Science S.A.