Residual stress of annealed electroless and electrodeposited nickel phosphorous layers incorporated with amorphous boron particles

Abstract

This paper discusses the effects of thermal annealing, the presence of boron and the current density on the residual stress of electroless and electrodeposited nickel phosphorous, NiP, and nickel phosphorous boron, NiPB, and composite coatings. Besides residual stress, the hardness, Young’s moduli, and elastic strain to failure, \(\frac{H}{E}\), were determined via nanoindentation. It is shown that all coatings, independent of their preparation or annealing procedure, possess compressive residual stresses. A pin-on-disc tribometer was used with a load of 3 N without lubricant to determine the friction coefficient and the wear resistance of the layers. Results from wear tests correlate with the calculated \(\frac{H}{E}\), in which coatings with higher \(\frac{H}{E}\) have a higher wear resistance. It is shown that annealing of the coatings at 400 °C provides the highest wear resistance except for electroless and electroplated NiP. Lastly, the feasibility of the X-ray diffraction method to determine the residual stress of NiP and NiPB coatings was tested. It was found that NiPB dispersion coatings could not be characterized through this method due to the lack of reflections at high 2θ values. Only the residual stress of Ni{311} could be determined in the case of NiP layer that was heat treated.