A Novel Approach to Achieve Thick Single Phase Fe2B Coating by Alternating Current Field Enhanced Pack Boriding

Thick single phase Fe2B coatings were prepared on plain carbon steels by a novel alternating current field enhanced pack boriding (ACFEPB). Samples were set between a pair of parallel electrodes on which a 50 Hz alternating current field (ACF) with a current of 4A was applied during a 4 h pack boriding. The coating's structure, phases, thickness, and hardness distribution were characterized. The results showed that the ACF could greatly promote pack boriding and lead to the formation of a single phase Fe2B coating with a thickness of more than 100 μm by 4 h pack boriding at 800°C. It was proposed that the ACF had an effect on promoting diffusion of boron and iron in the treated samples by producing more vacancies in samples’ subsurface. The ACF should also have effects on enhancing diffusion and chemical reactions in the boriding media.