Objectives

• Review of current understanding
• Evaluation of laboratory tests to determine acceptable practice
• Development of understanding of steam oxidation in a range of alloy classes
• Development of a measurement method for thermal conductivity of oxide scales
• An improved model for oxide spallation in 9- and 12-Cr steels.

Introduction

Components in high temperature plant are exposed to steam atmospheres over a range of temperatures and pressures. Current material selection is based upon mechanical strength; usually creep. However, lifetimes are also limited by oxidation of components. Hence it is also of great importance to consider the oxidation characteristics of materials during the selection process.

A need therefore was identified to develop better understanding of steam oxidation and in particular the influence of laboratory test procedures on the resultant data and the effect of alloy composition on the oxidation resistance of materials with similar chromium content.

Additionally the presence of an oxide scale has been shown to reduce the thermal conductivity of components in a heat transfer situation; accurate data on the thermal conductivity of scales is also required in order to help model the temperature profile and thermal transfer in high temperature components.