High-Temperature Oxidation Behavior of a Diffusion-Bonded Cr–Fe–C–WC Complex Carbide Composite

Abstract

Oxidation resistance of ceramic composites is one of the primary requirements since these composites often experience high temperature under oxidative conditions. The present work concentrates on the high-temperature oxidation behavior of a recently developed optimized diffusion-bonded Cr–Fe–C-based complex carbide composite to understand its oxidation kinetics, oxide-film stability, and degradation mechanisms. The composite consists of 10 wt% WC, 10 wt% Cr, and 80 wt% Cr–Fe–C carbide. Spark plasma sintering (SPS) was carried out at 1200 °C under a uniaxial pressure of 30 MPa, with a dwell time of 15 min and a heating rate of 100 °C·min⁻¹ under vacuum. In this material design, chromium acts as a diffusion-assisting phase rather than a retained metallic binder. This results in a chemically graded multi-carbide microstructure without a continuous binder phase. Isothermal oxidation tests were conducted in air at 500, 650, and 800 °C for 12 h using continuous mass-gain measurements. The composite exhibits strong temperature-dependent oxidation behavior, characterized by low specific mass gain and early kinetic saturation across the examined temperature range. Parabolic rate analysis and Arrhenius fitting yield an apparent activation energy of 89.5 ± 5.4 kJ·mol. Post-oxidation characterizations using SEM, EDS, and XPS reveal a temperature-dependent evolution of oxide morphology and chemistry. Chromium-derived oxides form the most stable and surface-retained oxide backbone at elevated temperatures.