Boron coating to combat corrosion and oxidation

The present study describes the recent investigation of boronized surface coating on Steel, Ni super alloy and pure Tantalum. The coatings were produced by thermo-chemical treatment with an original technology powder mixture at the temperature range of 850-1050°C. Metallographic examination, X-ray diffraction (XRD) and microhardness testing were used to determine the characteristics of the diffusion layer compared with the substrate. The continuous weighting method and the potentiodynamic polarization measurements were used to investigate the corrosion resistance of the specimen surface before and after boronizing. Also, the high temperature oxidation method detected by differential thermal analysis (TGA) was used to observe the oxidation resistance of unboronized and boronized specimens. It was shown that the boronizing process created a boride layer with a thickness of 10-80 μm depending on substrates, temperatures, and times, with microhardness of about 8-10 times greater than that of the substrate. The corrosion resistance of the boronized coating was determined to be 6-10 times higher than that of the substrate. As well, the oxidation resistance of the boronized coating was 3-5 times better than that of the substrate.