Effect of annealing temperature on microstructure, mechanical and tribological properties of nano-SiC reinforced Ni-P coatings

Abstract

Abstract:The tribological properties of Ni-P/SiC nanocomposite coatings annealed at different temperatures (350-500 °C) were investigated in order to determine the optimal temperature needed to enhance their wear resistance as well as to reveal the underlying wear mechanisms. With increasing annealing temperature, the hardness of the annealed coatings gradually decreased from 8.2±0.5 to 7.1±0.6 GPa as a result of the Hall-Petch effect, nevertheless these values obtained were constantly higher than that of the as-plated coating (6.3±0.3 GPa) due to the formation of a hard Ni3P phase.Regarding to tribological properties, the Ni-P/SiC coating annealed at 350 °C presented a poorer wear resistance (6.1×10 -5 mm 3 /Nm) compared to the as-plated coating (3.9×10 -5 mm 3 /Nm) owing to a rougher original contact surface and the subsequent generation of nickel and iron oxides on the wear track. In contrast, coatings annealed at temperatures ranging between 400-500 °C exhibited the improved wear resistance (4.3×10 -5 -7.8×10 -6 mm 3 /Nm) attributable to their smoother surfaces and to the lubrication effect of H3PO4 arising from the tribochemical reaction between Ni3P and the environment. Overall, the Ni-P/SiC coating annealed at 500 °C containing the largest amount of Ni3P exhibited the lowest friction coefficient (0.51) and wear rate (7.8×10 -6 mm 3 /Nm).Keywords: Nickel-phosphorus; SiC; Electroplating; Tribology; Annealing. IntroductionProtective coatings have attracted scientific interest for decades due to their potential to increase resistance to wear and corrosion, which are estimated to account for 3-4% of the world's Gross [16] and CNTs [17] were incorporated into Ni-P coatings to enhance their mechanical and tribologicalproperties. As reported in Table 1, incorporation of reinforcing particles increases the hardness of Ni-P coatings, especially when SiC particles were used. Moreover, studies [18,19] have demonstrated that the incorporation of SiC particles in a Ni-P matrix is the most effective combination of cost and performance in industrial applications.Regarding Ni-P/SiC composite coatings, SiC particles with a size ranging between 0.5-6.0 µm was mostly used [20][21][22][23][24][25], while only a few studies investigated the use of nano-sized SiC particles (40-50 nm) [26][27][28][29][30][31][32]. However, it is worth noting that these studies investigated only the effects of SiC nanoparticles on the microstructures, corrosion resistance [26][27][28][29][30] and wear resistance of the as-plated coatings [31,32]. Therefore, there is still a large gap in the relationship between microstructure, mechanical and tribological properties of Ni-P/(nano)SiC coatings. In particular, the effects of postdeposition heat treatments on the tribological properties is still unexplored.In this study, SiC particles with a nanometric size were incorporated in Ni-P coatings, and the effects of different annealing temperatures on the microstructure, mechanical and tribological properties of the composite coatings was investigated and...

Evolution of structural, mechanical and tribological properties of Ni–P/MWCNT coatings as a function of annealing temperature

“…lower friction coefficient (0.71±0.031~0.86±0.042) than the as-plated condition (0.87±0.055). This discrepancy is attributed to the different tribochemical reactions during the tribotest as described below [40]: According to the standard Gibbs free energy [41][42][43] It is worth noting that the Ni-P/MWCNT-400 coating exhibits the lowest friction coefficient of 0.71±0.031 amongst the annealed samples. Except for the lubrication effect of H 3 PO 4 as mentioned above, there are two reasons contributing to such a outcome.…”

Study of the effect of pulse plating parameters on the electrodeposition of NiP and NiP/SiC coatings and their microhardness values

“…Multiple diffusion-driven phenomena are developed during heat treatment such as crystallisation, grain boundaries formation, grain boundary migration, grain growth, Ni 3 P and other Ni-P intermetallic phase precipitations. 11,48 In addition, these coatings were heat treated in air; therefore an oxide layer was produced on the surface of these coatings, which also smooths their surfaces.…”

“…7,9,10 Typically, a treatment of 400°C for an hour provides the maximum hardness. [10][11][12] However, it is not applicable to all conditions.…”

“…Figure11. The relation between microhardness before and after heat treatment with frequency, wt.%SiC and wt.%P in NiP/SiC coatings (deposited at dc: 50%, i ave : 4 A dm −2 ).…”

Surfactant-Free Electroless Codeposition of Ni–P–MoS2/Al2O3 Composite Coatings

“…The incorporation of solid particles into the matrix could remarkably improve the mechanical and physiochemical properties of composite coatings. For example, hard particles such as Al 2 O 3 [4,5], SiC [6,7], SiO 2 [8], TiO 2 [9], and diamond [10] enhance the hardness and wear resistance of composite coatings. Solid lubricant particles such as MoS 2 [11,12], PTFE [13], and BN(h) [14] lower the frictional coefficient of composite coatings and consequently reduces wear loss.…”