Influence of temperature, impact angle and h-BN content on the erosive wear behavior of hot-pressed SiC-BN composites

Abstract

Owing to the unique combination of high strength, high hardness, and excellent thermal shock resistance, SiC-BN composites can be a potential candidate for components of exhaust systems where material loss by erosion is a major concern. In view of the foregoing, the present investigation deals with the solid particle erosion behavior of hot-pressed SiC composites with varying h-BN content: 0, 4, and 10 vol%. Erosion tests were conducted using SiC particles (size of 50–70 μm) at different impingement angles: 30°, 60°, and 90° and temperature: room temperature (25 °C) and high temperature (800 °C). The dominant erosive wear mechanisms were determined using SEM-EDS, XRD, Raman spectroscopy and XPS analyses. Results indicated that the erosion rate of the investigated composites decreased with the addition of h-BN and at shallow angles of impingement and high temperature. Among the investigated composites, SiC-4 vol% BN composites exhibited the least erosive wear at a given temperature and impingement angle, while the maximum erosive wear obtained for monolithic SiC ceramics at 25 °C and 800 °C. Fracture and deformation of SiC grains along with the pull-out of BN platelets are identified as the major mechanisms of material removal for the investigated SiC-BN composites. The presence of SiO2, B2O3 or SiO2·B2O3 phases is observed on the surface of composites eroded in high temperature conditions.