Microstructure and Corrosion Resistance of Ni-Al Coating Prepared by Plasma Transferred Arc Technology

The Ni-Al intermetallic compounds coating was prepared on Q235 steel plate through plasma transferred arc (PTA) process using different powder system compositions. The compositions included high-purity Ni: Al, NiBSi: Al and NiCrBSi: Al, with a Ni: Al ratio of 3:1. The phase composition, microstructure, morphology, and corrosion resistance of the coatings were analyzed. The results indicated that the microstructure of the coatings changed to hypoeutectic with the addition of alloying elements in the powder system. The coatings prepared with high-purity Ni powder had low hardness and poor corrosion resistance due to the coarse dendrite structures of Ni-Al intermetallic compounds. The coatings produced with NiBSi powder contained lamellar eutectic structures and had good corrosion resistance and high hardness, as the Ni3Al phase grew in the NiAl phase. The coating fabricated with NiCrBSi powder showed a high density of chrysanthemum-like eutectic structures alternately formed by Ni3Al and a-Cr, and had refined grain size, good corrosion resistance, and high hardness.

Automated summary

Ni-Al intermetallic compounds coating was prepared on Q235 steel plate using different powder systems compositions. The microstructure of the coatings changed with the addition of alloying elements. The coatings prepared with NiBSi powder had good corrosion resistance and high hardness, while the coatings fabricated with NiCrBSi powder showed refined grain size, good corrosion resistance, and high hardness.