Microhardness, Friction and Wear of SiC and Si3N4 Materials as a Function of Load, Temperature and Environment.
Abstract
Temperature - and load-variable microhardness tests have been used to study the changing incidence of plasticity and fracture in SiC, Si3N4 and Si materials as a function of specimen microstructure. The decrease of hardness with temperature was more marked for SiC than for Si3N4 materials, such that the room temperature superiority of SiC over most forms of Si3N4 (only PDSN (pyrolytically deposited Si3N4) has comparable room temperature hardness)) was not maintained above v approx. 600 C. The hardness/temperature curve for (111) single crystal Si was similar in form to those reported by previous workers. Microstructural influences on hardness were more pronounced in Si3N4 than in SiC. Grain boundaries were generally observed to cause softening, and often provided preferred fracture paths, especially in fine-grained materials and especially at high temperature (800 C). However, fracture toughness values were highest for fined-grained materials, probably due to crack deflection by grain boundaries.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1980
- Accession Number
- ADA107501
Entities
People
- M. G. S. Naylor
- T. F. Page
Organizations
- University of Cambridge