Improved thermal stability and oxidation resistance of electrodeposited NiCrP amorphous alloy coatings

Amorphous NiP and NiCrP alloy coatings were prepared on copper substrates by electrodeposition. The thermal stability of the obtained coatings were evaluated by the onset temperature of phase transformation identified with differential scanning calorimetry measurements, and their high temperature oxidation resistances were characterized by the oxidation kinetics curve and the oxidation activation energy. The mechanism of the doping effect of Cr element on crystallization temperature and oxidation resistance of the alloy coatings were discussed based on X-ray diffraction analysis. The results show that the crystallization temperature of NiP amorphous alloy was $$344^\circ \hbox {C}$$ , and the oxidation activation energy was calculated to be $$1.54 \times 10^{\mathrm {3}}\hbox { J mol}^{\mathrm {-1}}$$ . As for NiCrP alloy coating with a Cr content of 1.8 wt%, the crystallization temperature increased to $$403.8^\circ \hbox {C}$$ and the calculated oxidation activation energy was $$3.53 \times 10^{\mathrm {4}}\hbox { J mol}^{\mathrm {-1}}$$ , 2.29 times higher than the NiP coating. The remarkably enhanced high-temperature oxidation resistance of NiCrP alloy coating can be attributed to the compact metal oxide film formed on the surface.