Corrosion tests - A very important investigation method for the selection of refractories for glass tanks

Abstract

For determining and comparing the corrosion behavior of refractories against glass melts, a good reproducibility of the corrosion tests is needed. In the present paper the reproducibility of the various most common corrosion tests, the respective procedures and the applied evaluations are discussed. The investigation was carried out with fused-cast AZS material because it has an inhomogeneous microstructure, so that the reproducibility with this material is not as good as that of the corrosion tests with refractories which have a homogeneous microstructure. The investigated corrosion tests are: dynamic finger test, rotating cylinder face method, small rotating furnace test, crucible test, static finger test and static plate corrosion test. Among these methods the static plate corrosion test combines a good reproducibility with many advantages (disadvantages were not observed). An international round-robin investigation within the Technical Committee 11 of the International Commission on Glass confirmed the good reproducibility of the static plate corrosion test, and the TC 11 recommended it as standard corrosion test. In the present paper, moreover, the influence of the most important parameters on the static plate corrosion test is discussed. Besides the additional bubble drilling in the fluxline area, which can be eliminated directly by the evaluation, a possible influence of saturation, of evaporation or of initial processes must be considered and eliminated if necessary. For this reason the knowledge of the corrosion behavior for the various most common combinations refractory/glass melt is important, which will be determined within a round-robin investigation by TC 11 in the near future.