Wear Behaviour of Electroless heat Treated Ni-P Coatings as Alternative to Electroplated hard Chromium Deposits

Abstract

In this present study was evaluated the influence of heat treatment on the wear resistance of electroless high phosphorus nickel coating (9-10% P wt.). In addition, both untreated and treated Ni-P deposits were then compared to electroplated hard chromium coatings in terms of wear behaviour. Three different heat treatment conditions were performed at temperatures of 320ºC, 400ºC and 500ºC under different holding times. The selection of the heat treatment conditions was chosen considering the results obtained by a differential scanning calorimetry (DSC) analysis. The wear behaviour of the Ni-P samples was investigated through a non-lubricated "ball on plate" test carried out against an Al 2 O 3 counter-face. After an analysis of the friction coefficient, microstructure of the worn surface, width and chemical composition of the wear track, was possible to conclude that the heat treatment affect positively the wear resistance of Ni-P coatings. Treatment conditions of 320ºC with 9 hours holding time and 400ºC with 1 hour holding time showed the best results due to a structural change from amorphous supersatured solid solution of phosphorus in nickel to a crystalline structure of nickel crystallites and nickel phosphides (Ni 3 P) occurred between 320ºC and 360ºC that was verified after x-ray diffraction analysis. Moreover, Ni-P heat treated coatings showed better results when compared to electroplated hard chromium deposits, hence acting as a natural alternative for chromed coatings.

Heat treatment and quenching effects on wear of electroless nickel–phosphorous plating

“…They concluded that the heat-treatment results in the formation of the Ni 3 P phase on the coated surface are responsible for enhancing hardness. Goettems & Ferreira (2017) found that electroless Ni-P deposits with post-heat-treatment at 320°C (9 h) and 400°C (1 h) have shown a better wear resistance than electroplated hard chromium coating. They also concluded that this is due to the formation of nickel crystallites and nickel phosphides (Ni 3 P).…”

“…This structure also influences the wear resistance of the electroless Ni-P. It has been reported in the literature that, due to Ni--P coating on steel, improved tremendous wear resistance after heat treatment at 320°C and 400°C (Samuel & Zoppas, 2017;Uday Venkat Kiran et al, 2019).…”

Optimization of electroless bath process parameter for improving the tribology behavior of Ni-P/CaBr2 composite coating against the hardened EN-31 steel

“…The formation of nodules mainly depends upon the rate of nickel deposition. For example, the size of the nodule decreases with increase in the nickel deposition [27] and vice versa. Similarly for the reinforcement of CaBr 2 , the high rate of nickel deposition has affected the nodular formation.…”

Structural Characterization, Global and Local Electrochemical Activity of Electroless Ni–P-Multiwalled Carbon Nanotube Composite Coatings on Pipeline Steel

“…These coatings are based on conventional binary Ni-P films and have consolidated engineering applications in the automotive, aerospace, and food industries [13]. They owe their outstanding performance to a combination of strong adhesion in a variety of substrates, shapes and sizes, and high hardness in the annealed state, due to the precipitation of nickel phosphides promoting good wear and corrosion resistance [14,15]. In recent decades, further developments in the electroless deposition of nickel-based coatings have been driven by growing needs for optimized surface properties of metallic materials to expand their applicability to more aggressive environments.…”