Study On Preparation And Characterization Of Ni-Mo-Al-RE-MoSi₂ Composite Coating

In this paper, Ni-Mo-Al-MoSi₂ and Ni-Mo-Al-RE-MoSi₂ composite coatings were prepared as the bond coating by pulse plating method. The effects of PEG6000 concentration, pH value, AlCl3 concentration, MoSi₂ concentration, temperature, current density, frequency, duty-cycle, stir speed, plating time and RE ion on Al and Si content of composite coatings were studied, and the optimal operating conditions were studied. The morphology surface, compositions and structure of composite coatings were analyzed by SEM, EDX, XRD respectively. The CTE of Ni alloy and Ni alloy+different composite coatings were tested by DIL. From the research, the conclusions were as followed:The result showed that the Al and Si content of Ni-Mo-Al-MoSi₂ composite coating under the optical conditions were 2.35% and 2.23% respectively. While the Al and Si content of Ni-Mo-Al-Y-MoSi₂ composite coating under the optical conditions were 8.78% and 1.46% respectively. The Al and Si content of Ni-Mo-Al-La-MoSi₂ composite coating under the optical conditions were 8.82% and 1.42% respectively. The Al and Si content of Ni-Mo-Al-Pr-MoSi₂ composite coating under the optical conditions were 6.35% and 1.57% respectively.SEM showed that compared to Ni-Mo-Al-MoSi₂, on the surface of Ni-Mo-Al-RE?Y, La, Pr, Nd?-MoSi₂ composite coating there were fewer nodules and the surface was more smooth.EDX showed compared to Ni-Mo-Al-MoSi₂, the Mo content of Ni-Mo-Al-RE?Ce, Pr, Nd, Sm, Dy?-MoSi₂ composite coatings was improved. Compared to Ni-Mo-Al-MoSi₂, the Al content of Ni-Mo-Al-RE?Y, La, Ce, Pr, Nd?-MoSi₂ composite coatings was higher.XRD indicated that compared to Ni-Mo-Al-MoSi₂ composite coating, the 2? of peaks in the Ni-Mo-Al-RE-MoSi₂ composite had a different degree of skewing, which manifested that there were RE in Ni-Mo-Al-RE-MoSi₂ composite coating.Thermal expansion curves indicated the thermal expansion coefficient of Ni alloy and Ni alloy+different composite coatings were as followed:Ta?Ni alloy?>Ta?Ni alloy+Ni-Mo-Al-Y-MoSi₂?>Ta?Ni alloy+Ni-Mo-Al-La-MoSi₂?> Ta?Ni alloy+Ni-Mo-Al-MoSi₂?>Ta?Ni alloy+Ni-Mo-Al-Pr-MoSi₂??Creative ideas in this paper:The current literatures about the preparation of Ni-Mo-Al-MoSi₂ composite coating and Ni-Mo-Al-RE-MoSi₂ composite coating by pulse Electrodeposition have not been reported.