Corrosion resistance of borided layers obtained on XC38 steel

Abstract

Many works were made on the mechanical characterization of borided layers, but studies on the corrosion resistance of these layers are limited. In this work, an evaluation of corrosion resistance of boride coatings on XC38 steel in specific acid and basic solutions (HCl 1N, H₂SO₄ 1N, H₃PO₄ 1N, NaOH 1N, and KOH 1N) was carried out. The formation of iron boride layers (FeB and Fe₂B) on the material surface was obtained in solid medium by pack cementation process. Boriding treatment at 900°C for 4 h in a powder mixture consisting of 90% SiC, 5% B₄C and 5% NaBF₄ allow to boride layer of about 160 microns thickness.<br> The corrosion behavior was evaluated by weight loss curves after total immersion tests. The results obtained show that in general, corrosion resistance of borided layers is improved compared to that of XC38 steel without Boriding. This improvement varies from one medium to another, and the best improvements were obtained in acidic environments, particularly in sulphuric acid.