Effect of Ni and Fe elements on microstructure and high temperature oxidation behavior of laser cladding aluminum bronze coating

Abstract

In this work, two kinds of aluminum-bronze coatings were successfully prepared on 316 stainless steel substrate by laser cladding technology. The changes of microstructure and high temperature oxidation behavior of pure aluminum bronze laser cladding layer before and after adding Ni and Fe elements were studied and compared. The results show that a certain amount of κ phase and Fe–Cr phase are constituted in the modified coating with the addition of Ni and Fe elements, which refines the structure and grains. The main components of the oxide layer of the two coatings are Al2O3. In the high temperature oxidation process, both two coatings experienced the formation, spallation, and recovery of an oxide film. The time to form a stable oxide film on the surface of the modified coating is significantly shorter than that of the original coating. As a result of the formation of fine and dense oxide particles on the modified coating's surface, the stability and internal stress resistance of the oxide film is superior. Under the condition of 1000 °C oxidation for 100 h, the oxidation film thickness and oxidation rate constant (kp) of the modified coating are about 0.88 and 0.79 times of that of the original coating. The addition of Ni and Fe can greatly enhance the laser cladding aluminum bronze coating's resistance to high-temperature oxidation.