THE CORROSION BEHAVIOR OF CHROMIUM NITRIDE FILM ON AISI 4140 AND H13 STEELS.

Chromium nitride film (CrN) was prepared on steel substrates, AISI 4140 and H13 with variations in the substrate roughness, using the reactive DC magnetron sputtering technique at room temperature in controlled partial pressures of Ar and N2 gas atmospheres. The films were polycrystalline, as confirmed by X-ray diffraction analysis. The corrosion behavior was investigated using an electrochemical technique in 3.5 wt% NaCl solution with various pH values at room temperature. The results indicated that the CrN-coated AISI H13 presents better corrosion resistance than the CrN-coated AISI 4140 at pH 2 and 7, but worse at pH 10. In addition, the rate of corrosion decreased with a reduction of the surface roughness. The chemical states of the corrosion product were clearly identified by spatially resolved secondary electron yield X-ray absorption spectroscopy with X-ray photoemission electron microscopy. It was found that Cr2O3 is formed on the non-corroded CrN film and the AISI H13 substrate, whereas Fe2O3 is formed on the corroded surface and the AISI 4140 substrate. [ABSTRACT FROM AUTHOR]