Effect of Laser Remelting on Friction-Wear Behaviors of Cold Sprayed Al Coatings in 3.5% NaCl Solution

Abstract

A cold sprayed Al coating on S355 structural steel was processed using a laser remelting (LR). The surface and cross-section morphologies, chemical compositions, and phases of as-obtained Al coating before and after LR were analyzed using a scanning electronic microscope (SEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively, and their hardness was measured using a micro-hardness tester. The friction-wear behaviors of Al coating before and after LR in 3.5% NaCl solution were conducted to simulate the sand and gravel scouring on its surface in seawater, the effects of wear loads and speeds on the tribological properties of Al coating were analyzed, and the wear mechanisms under different wear loads and speeds were also discussed. The results show that the Al coating after LR is primarily composed of an Al phase and its hardness is 104.66 HV, increasing 54.70 HV than the cold sprayed Al coating. The average coefficient of friction (COF) of cold sprayed Al coating at the wear load of 0.5, 1.0 and 1.5 N is 0.285, 0.239, and 0.435, respectively, while that after LR is 0.243, 0.227, and 0.327, respectively, decreased by 14.73%, 5.02% and 24.83% compared to the cold sprayed Al coating. The wear rate of cold sprayed Al coating at the wear load of 0.5, 1.0 and 1.5 N is 1.60 × 10−4, 2.36 × 10−4, and 2.40 × 10−4 mm3/m·N, respectively, while that after LR is 1.59 × 10−4, 1.70 × 10−4, and 1.94 × 10–4 mm3/m·N, respectively, decreased by 1%, 32%, and 23%, respectively, indicating that LR has high anti-friction performance. Under the wear load action of 1.0 N, the average COF of laser remelted Al coating at the wear speeds of 300, 400 and 500 times/min is 0.294, 0.279, and 0.239, respectively, and the corresponding wear rate is 1.06 × 10−4, 1.24 × 10−4, and 1.70 × 10−4 mm3/m·N, respectively. The wear mechanism of cold sprayed Al coating is primarily corrosion wear at the loads of 0.5 and 1.0 N, and that at the load of 1.5 N is abrasive wear and fatigue wear; while that after LR is abrasive wear and fatigue wear, with no corrosion wear, showing that LR improves its corrosion and wear resistance.

Assessing corrosion resistance of two-dimensional nanomaterial-based coatings on stainless steel substrates

“…Coating an exposed surface of SS, or any structural metallic material is the most prevalent technique for corrosion prevention [16,17]. However, metallic coatings (laser-remelted Al) have demonstrated poor performance when subjected to large wear loads [18], and inorganic pigments have concerning toxicity [19]. Nanoparticle metal oxide coatings have also been considered for corrosion protection, but thin-film metal oxide coating techniques such as atomic layer deposition (ALD) are expensive and energy-intensive.…”

Microstructure and Tribological Properties of Laser Forming Repaired 34CrNiMo6 Steel

“…The wear rate is calculated by the following equation [ 33 , 34 ]: W = V/(S × P) = Δm/(ρ × S × P) [mm 3 /N·m], where V is the worn volume, P is the normal load, S is the total sliding distance, △m is the wear loss, and ρ is the density of the 34CrNiMo6 steel. Figure 10 shows the wear rates of the three kinds of samples.…”

Effect of Gas Propellant Temperature on the Microstructure, Friction, and Wear Resistance of High-Pressure Cold Sprayed Zr702 Coatings on Al6061 Alloy

“…Their intensities gradually become sharper as the loads increase, insinuating a dominant abrasive wear mechanism. Considering that S1 had a greater amount of pores, the stress concentration at the point of tribological contact which can induce fatigue cracks from the influence of circular stress due to the brittle nature of CS coatings [31,86,112]. This increases the chance of enabling a fatigue wear mechanism of which brittle fractures occur from the buildup of microslips along the contacting asperities.…”