High temperature oxidation of Cr-ZrO2-Al2O 3 composites

Abstract

The high temperature oxidation resistance of Cr-ZrO₂-Al ₂O₃ composites fabricated by mechanical alloying (MA) and spark plasma sintering (SPS) has been studied. High temperature oxidation tests (900-1100°C) under still air for 72 hours, have revealed good oxidation resistance (1.8, 2.6 and 15.3 mg/cm² at 900, 1000 and 1100°C respectively) since a protective Cr₂O₃ layer forms upon heating. EDAX analysis revealed that ionic Cr diffusion takes place at 1100°C from the bulk towards the composite's surface leading to a Cr-depletion at the near surface-zones. Chromium contained in the bulk tends to oxidize through oxygen diffusion apparently acting along the grain boundaries. The products of oxidation were studied by x-ray diffraction and scanning electron microscopy. copyright The Electrochemical Society.