Surface modifi cation of ferrosilide alloys for anode earthing

Abstract

It is known that the disadvantages of ferrosilide earthing devices are their fragility, which leads to their frequent mechanical damage. Their fragility is increased with increasing silicon content. The solution to this problem is to reduce the content of silicon in the alloy, but this greatly increases the rate of dissolution of the resulting alloy. As a result, the possibility of reducing the dissolution rate of ferrosilides with a silicon content of 9…12% due to thermal oxidation and treatment in a phosphoric acid medium was studied. The most promising method for anode grounding conductors is the method of processing materials in orthophosphoric and metaphosphoric acids with the formation on the surface of a phase of iron silicide highly resistant to anodic dissolution due to selective etching of the alloy. The relationship between the phase composition of the films showed that mainly phases of silicon oxide (SiO2) and magnetite (Fe3O4) predominate in the alloys, as a result of which the dissolution rate is significantly reduced. As a result of heat treatment of ferrosilide alloys with a silicon content of less than 14%, a decrease in the dissolution rate does not occur due to the high porosity of the formed films and the presence of phases that do not have protective properties. The anodic dissolution rate is the lower, when the grain size of the alloy used is the larger.