Oxidation Behavior at High Temperature of Cr-Al_2O_3 and Nb-Al_2O_3 Composites Fabricated by Mechanical Alloying and Spark Plasma Sintering

摘要

The isothermal oxidation resistance of Cr-Al_2O_3 and Nb-Al_2O_3 composites fabricated by mechanical alloying (MA) and spark plasma sintering (SPS) has been evaluated. Studied composite powders were prepared by ball milling 50vol% Cr-Al_2O_3 and 50vol% Nb-Al_2O_3 respectively, at different times (1,3.5 and 7h). Powders were then compacted by SPS in less than 5 min, so that a particular metal-ceramic interpenetrating network has been obtained. High temperature oxidation tests (700°C), under air atmosphere have revealed a better corrosion resistance for the Cr-Al_2O_3 composite since a protective Cr_2O_3 layer immediately forms upon heating. The Nb-Al_2O_3 composite had the highest weight gain, at all the ball milling times, i.e. 1, 3.5 and 7h, with 45mg/cm~2, 160 mg/cm~2 and 200 mg/cm~2 respectively, whereas the Cr-Al_2O_3 composite had the lowest weight gain (2 mg/cm~2) for 3.5h milling time and 1310°C/4min sintering operation.