Evaluations of blister-like fractures and critical PV-values of carbon mechanical seals by thermal shock test

Abstract

The formation of a blister-like fracture, one of the troublesome phenomena observed on the sliding surface of a carbon mechanical seal, is simulated by a model depicting the distribution of thermal stresses in a locally heated disk. The critical pressure-velocity values (PV-values) of a carbon mechanical seal are expressed in two ways, each containing a parameter, which, for the edge crack, is given by the thermal shock resistance, δ, and, for the center of blister on the sliding face, by the thermal shock fracture toughness, ▽. These parameters were experimentally measured for 11 kinds of carbons by using a series of disk testing methods. Practical performances of mechanical seal rings made of these carbons are discussed in relation to the determined parameters.