|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Materials for High Temperature Applications: Next Generation Superalloys and Beyond
||The Effect of Borosilica Pack-Cementation Coatings on the Oxidation Resistance of Mo-Si-B Based Alloys
||John H. Perepezko, Daniel Schliephake, Camelia Gombola, Martin Heilmaier
|On-Site Speaker (Planned)
||John H. Perepezko
High-temperature materials like Mo-Si-B alloys can increase the efficiency of engines by higher combustion temperatures. They show good creep and oxidation resistance at high temperatures but suffer from low ductility at ambient temperatures. Recently, novel Ti-rich Mo-Si-B alloys have shown an increased creep resistance compared to ternary reference alloys by the formation of Ti-silicide precipitates. However, Ti additions deteriorate the oxidation resistance. Hence, coatings are required to provide sufficient oxidation resistance. The coating was applied by pack cementation codeposition of B and Si. The coating structure has an outer borosilica layer followed by an inner MoSi2 and Ti5Si3 layer for the Ti-rich alloys. Tensile creep tests were carried out from 1100°C to 1200°C in air. Cyclic and isothermal oxidation tests were performed between 800°C and 1200°C for up to 3000 h. Microstructural analysis was used to identify mechanisms for the superior resistance of coated samples.