Thermal stability of electrodeposited nanocrystallinenickel assisted by flexible friction
(1. School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China;
2. National Key Laboratory for Remanufacturing, Academy of Armored Forces Engineering, Beijing 100072, China;
3. National Engineering Research Center for Mechanical Products Remanufacturing,
Academy of Armored Forces Engineering, Beijing 100072, China)
2. National Key Laboratory for Remanufacturing, Academy of Armored Forces Engineering, Beijing 100072, China;
3. National Engineering Research Center for Mechanical Products Remanufacturing,
Academy of Armored Forces Engineering, Beijing 100072, China)
Abstract: Nanocrystallinenickel coating was prepared by flexiblefriction assistedelectrodeposition technology in an additive-free Watts bath.The coating consists of massive equiaxial crystals with an average grainsize ofabout24 nm and exhibits a (111) preferred orientation. The differential scanning calorimetry (DSC) analysis ofnanocrystallinenickel demonstrates that the peak temperature of rapidgraingrowth is about285.4 °C, and the peak temperature of grain growthtowards equilibrium is around431.5 °C. The isochronousannealingresults reveal that abnormal graingrowth behavior is notobserved in nanocrystallinenickel without sulfur-containing. The thermal stability of the deposition was improveddue to its initialmicrostructure of the as-deposited nickel and a certainamount of annealing nano-twins with low-energy, which reduces the driving force for grain growth. Consequently, the coating shows a lowresidualtensile stress of about50 MPaand a high microhardness of HV 400 at the annealing temperature of 450 °C.
Key words: electrodeposition; nanocrystalline nickel; flexible friction; thermal stability; grain growth