Investigation of Mechanical Behavior in Plasma NitridedNickel-Boron-CNT Composite Coatings Using Response Surface Methodology

The objective of this study was to statistically analyze the effects of plasma nitriding using response surface methodology(RSM).The RSM, which is dependent on a core composite construction, was used to study the effects of variables like percentage nitrogen / hydrogen flow, deposition time, deposition temperature, and CNT concentration, on wear and corrosion behavior for electroless (Nickel-Boron-CNT)coating for low steel alloy.The results for plasma samples with different CNT concentration (0%, 0.35%, 0.7%) showed the effects of deposition temperature and time as well as percent hydrogen/nitrogen ratio on the corrosion rate.The results of microhardness showed that the highest microhardness value of (1200 HV) was achieved for the Ni-B coating containing 0.35 g/L CNT after plasma nitriding.The optimum design point for plasma nitriding (low wear rate, low friction coefficient, and extreme hardness) was achieved with a desirability of 0.95 at a temperature of 413.03C for 4h with H2/N2 percentage ratio of %54.17/%45.83 and a concentration of 0.35% CNT, whereas the lowest corrosion rate was achieved at a temperature of 387.78C for 2.53 h, with H2/N2 percentage ratio of 52.74/47.26and at a concentration of 0.35g/l CNT.This effect was amplified by raising the deposition temperature between 400 0C and 450 0C.Excellent corrosion resistance is exhibited by the Ni-B-CNT composite coating, and this resistance greatly increases as the concentration of CNTs increases.Excessive CNT deposition leads to agglomeration, harming the coating and reducing its corrosion resistance.