Corrosion and deterioration behavior of thermite welding alumina crucible used in railway

Abstract

Thermite welding of rails is now a standard operating practice to successfully join rails conjunctions in the field. Alumina crucible, an essential component of this operation, will be damaged and unusable after not more than 30 operations. This is due to direct contact of crucible with molten iron. Factors influencing this damage, including chemical reactions, penetration and infiltration of molten iron into the body, were studied using a scanning electron microscope equipped with X-ray spectroscopy (SEM/EDS) and X-ray diffraction. The results of this study supported by the kinetics of reaction between iron melt and alumina crucible in thermite welding showed that the thermite process does not significantly affect the crucible body component chemically; i.e. corrosion was not a major factor in crucible deterioration. The penetration and infiltration of melts into the crucible body via the grain boundaries and porosities were the major factor. A higher rate of the melt penetration into the parts containing impurities especially the silica was more harmful.