Oxidation Performance of High Temperature Mo-Si-B Alloys and Coatings

John H. Perepezko; F. Rioult; R. Sakidja

doi:10.4028/www.scientific.net/MSF.595-598.1065

Paper Titles

Thermal Effects of Continuous Laser Treatment on Ti-6 Al(wt%)-4V(wt%) Titanium Alloy
p.1033

Void Formation in Growing Oxide Scales with Schottky Defects and P-Type Conduction
p.1039

Oxidation and Nitridation of Pure Chromium at Elevated Temperature in Synthetic Air – Effect of Silicon Addition
p.1047

The Effect of Copper and Ceria Additions on the High Temperature Oxidation of Nickel
p.1057

Oxidation Performance of High Temperature Mo-Si-B Alloys and Coatings
p.1065

The Effect of CaO Coatings on the Oxidation Behaviour of Polycrystalline Nickel between 800 and 1200 °C
p.1075

The Effect of Thermal Expansion on Spallation Behavior of Fe-Base Alumina-Forming Alloys
p.1083

Void Formation and Filling under Alumina Scales Formed on Fe-20Cr-5Al Alloy Thin Foils
p.1093

The Role of Zr in the High-Temperature Oxidation of Fe₃Al
p.1103

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Oxidation Performance of High Temperature Mo-Si-B Alloys and Coatings

Abstract:

Mo-Si-B alloys are attractive due to their high temperature mechanical properties and high melting temperature. The oxidation of multiphase alloys develops in two distinct stages. First, there is a transient stage that corresponds to the evaporation of the volatile MoO3 and to an initial high recession rate. The steady state stage of the oxidation begins when the slower forming borosilicate layer becomes continuous and inhibits further rapid oxidation. Then, the oxidation rate is limited by oxygen diffusion through the borosilicate layer. In order to inhibit the transient stage, a coating strategy has been developed to capitalize on the interdiffusion reactions and to employ a kinetic bias to modify interface reaction products in order to maximize the high temperature stability and performance. In order to achieve a compatible interface coating together with enhanced oxidation resistance, a pack cementation process has been adopted to synthesize metal-rich silicide and borosilicide surface layers. The analysis of the enhanced oxidation performance indicates that a strategy based upon the operating principles of interface reactions in multicomponent systems is effective for developing stable and robust coating systems.