Friction Characteristics of Hardfacing Materials in High Temperature Sodium

Abstract

Friction and self-welding tests were conducted on several materials used for the contacting and sliding components of a sodium cooled fast breeder reactor. In the present study, the friction and self-welding characteristics of each material were evaluated through measuring the kinetic and breakaway friction coefficients. The influence of oscillating rotation and vertical reciprocating motion on the friction mode was also investigated.
The results obtained are as follows:
(1) Colmonoy No. 6, the nickel base hardfacing alloy, indicated the lowest kinetic friction coefficient of all the materials in the present study. Also, Cr₃C₂/Ni-Cr material prepared by a detonation gun showed the most stable friction behavior.
(2) The breakaway friction coefficient of each material was dependent upon dwelling time in a sodium environment.
(3) The friction behavior of Cr₃C₂/Ni-Cr material was obviously related with the finishing roughness of the friction surface. It was anticipated that nichrome material as the binder of the chrome carbide diffused and exuded to the friction surface by sliding in sodium.
(4) The friction coefficient in sliding mode of vertical reciprocating was lower than that of oscillating rotation.