Graded PVD Mo-Si interlayer between Si coating and Mo-Si-B alloys: Investigation of oxidation behaviour

The insufficient oxidation resistance of Mo-Si-B alloys at high temperatures inevitably requires a protective coating. A dual layer system combining a graded Mo-Si interlayer with a Si oxidation protective top layer has been applied by magnetron sputtering on a Mo-9Si-8B alloy. The interlayer architecture was designed to maximize the adhesion between top layer and substrate by creating thermodynamic compatibility between alloy and Si. Isothermal oxidation tests at 800 and 1200 degrees C in air up to 300 h were performed focusing on chemical reactions between top layer, interlayer and substrate as well as the evolution of the thermally grown SiO2.

Automated summary

In order to improve the oxidation resistance of Mo-Si-B alloys at high temperatures, a dual layer system was designed with a graded Mo-Si interlayer and a Si oxidation protective top layer to enhance adhesion. Long-term isothermal oxidation tests were conducted to study the chemical reactions and evolution of thermally grown SiO2 between the layers and substrate.