Contact Systems for High-Temperature Thermoelements Containing Nanocomposite Damping Layers

Abstract

To compensate for thermal stresses in high-temperature thermoelements (TEs), contact systems (CSs) are developed. These CSs contain nanocomposite damping layers formed by an array of carbon nanotubes (CNTs), in which the channels are partially filled with metal with high electrical conductivity. The CNTs are obtained by catalytic chemical vapor deposition using buffer layers based on Ti–Ni or Co–Nb–N. CNTs up to 7 μm thick are synthesized at a temperature of 700°C for 2 min. In the CSs, a Ni comutation layer up to 15 μm thick is formed on the surface of the CNTs by chemical or electrochemical deposition. Ni is deposited directly onto the CNT surface or onto a preliminarily sputtered Ni layer with a thickness from 100 to 500 nm. As a result, the TE legs with CSs are thermally stable up to 600°C. The CSs have a high adhesion strength up to 9.7 MPa and low specific contact resistance of about 10^–9 Ω m².