Wear Performance Analysis of Ni–Al2O3 Nanocomposite Coatings under Nonconventional Lubrication

Abstract

This article presents a wear study of Ni–Al2O3 nanocomposite coatings in comparison to uncoated steel contacts under reciprocating motion. A ball-on-flat type contact configuration has been used in this study in which a reciprocating flat steel sample has been used in a coated and uncoated state against a stationary steel ball under refrigerant lubrication. The next generation of environmentally friendly refrigerant HFE-7000 has been used itself as lubricant in this study without the influence of any external lubricant. The thermodynamic applications and performance of HFE-7000 is being studied worldwide, as it is replacing the previous generation of refrigerants. No work however has been previously performed to evaluate the wear performance of HFE-7000 using nanocomposite coatings. The wear scar developed on each of the flat and ball samples was studied using a Scanning Electron Microscope (SEM). The micrographs show that a combination of adhesive and abrasive wear occurs when using uncoated steel samples. Micro-delamination is observed in the case of Ni–Al2O3 nanocomposite coatings accompanied by adhesive and abrasive wear. Wear volume of the wear track was calculated using a White Light Interferometer. Energy-Dispersive X-ray Spectroscopic (EDS) analysis of the samples reveals fluorine and oxygen on the rubbing parts when tested using coated as well as uncoated samples. The formation of these fluorinated and oxygenated tribo-films helps to reduce wear and their formation is accelerated by increasing the refrigerant temperature. Ni–Al2O3 nanocomposite coatings show good wear performance at low and high loads in comparison to uncoated contacts. At intermediate loads the coated contacts resulted in increased wear, especially at low loads. This increase in wear is associated with the delamination of the coating and the slow formation of protective surface films under these testing conditions.

Novel experimental setup to assess Surfaces in tribo-contact lubricated by the next generation of environmentally friendly thermofluids

“…The only published works on the tribological assessment of hfEs are [15,16]. The study [15] was performed in 2002 which investigated the elastohydrodynamic and boundary lubrication performance of polyester (POE) in hfE-245mc and hfC-134a environment.…”

“…The study [15] was performed in 2002 which investigated the elastohydrodynamic and boundary lubrication performance of polyester (POE) in hfE-245mc and hfC-134a environment. a recent study [16] concerning the tribological performance of hfE-347mcc3 has been published in 2018. The study [16] however looks only into wear and there is no discussion about friction.…”

“…a recent study [16] concerning the tribological performance of hfE-347mcc3 has been published in 2018. The study [16] however looks only into wear and there is no discussion about friction.…”

Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines

“…Losses due to friction and associated wear can be reduced to an appreciable extent by applying surface-protective coatings and surface treatments on interacting machine parts and components [ 1 , 2 , 3 , 4 ]. Diamond-like carbon (DLC) coatings have been developed as a prominent surface-protective solution for widespread applications because of their outstanding mechanical, friction, wear, and chemical properties [ 5 , 6 , 7 , 8 , 9 ].…”

Impact of Al2O3 Particle Size on the Open Porosity of Ni/Al2O3 Composites Prepared by the Thermal Oxidation at Moderate Temperatures

“…Recently, nano-composite coatings have gained remarkable interest due to a significant improvement in protection performance [8][9][10]. Nickel-based coatings with Al 2 O 3 particles smaller than 100 nm in diameter have appeared and been used to increase the abrasion resistance of metal surfaces, especially in microdevices [11][12][13][14].…”