Corrosion Testing of Refractories and Ceramics

Corrosion Testing of Refractories and Ceramics

A. INTRODUCTION

In an echo to Lord Kelvin, who said, "When you cannot measure what you are speaking about or cannot express it in numbers, your knowledge is of a meager or unsatisfactory kind," much effort has been expended in developing tests to measure the corrosion resistance of refractories under slagging conditions and of structural ceramics under hot gas corrosion and oxidation at high temperatures, especially for non-oxide materials. Numerous methods have been tried and some reasonable correlations have been obtained for very specific conditions, but very few methods have reached the status of standard operating practices and none have yet been accepted for universal use. The main reason is that corrosion resistance data obtained in a laboratory environment very rarely simulate the conditions that prevail in service: sample size and geometry, state of stresses in the lining, thermal gradient and thermal cycling, as well as time, which are very difficult to be scaled down to fit with acceptable laboratory test conditions. It must always be remembered that accelerated tests, specially those done using very severe conditions, can lead to erroneous predictions.