Optimization of the Arc Spraying Process Parameters of the Fe–Base Mn-Si-Cr-Mo-Ni Coatings for the Best Wear Performance

Abstract

In this paper, the use of Fe-base Mn-Si-Cr-Mo-Ni and Fe-base Mn-Si-Cr wires for thermal arc spraying is presented. For this purpose the mechanical and physical properties of coatings were evaluated. The quality of the coating's was dependent on the selected equipment, spray materials, technological parameters of the spray and spray technology. The aim was to qualify and optimize the parameters for spray coating to get the best coatings properties with good tribological properties. All coatings were deposited on mild steel S235JR substrates. Two experimental cored wires of unique chemical composition-STEIN-MESYFIL 932 V and STEIN-MESYFIL 954 Vwere used for thermal arc spraying. The wires of 1.6 mm diameter were used for the surfacing material. Hardness, porosity and oxide measurements were used to verify the spray parameters and analyze the coatings. Rubber wheel test, which is based on the standard ASTM G65, was used. Dry-sand, rubber-wheel procedure according ASTM G65 was used to investigate low stress abrasion, whereas for high stress abrasion investigations a rubber wheel was used. This experiment was carried out by changing the speed of disc friction, travel distance and measuring the mass loss of surface friction. Miller Test according to ASTM G75-95 Standard was carried out in experiment with friction. The samples were immersed in water with corundum and polished with 22 N load, for 8 hours. Furthermore a correlation was performed between the spraying current and voltage parameter. The coatings' cross sections were examined using scanning electron microscope (SEM) and optical microscopy. The influence of the composite components of the coatings' microstructure, such as porosity, microhardness, oxide inclusions, on the tribological properties of thermal sprayed coatings is discussed in this paper.

Microstructure and Wear Performance of High-Velocity Arc Sprayed FeMnCrNiBNbAl Coating

“…This is because when the voltage gradually increases from low voltage, the arc temperature increases, the wire powder core can be fully melted, and the molten droplets can be effectively spread when they hit the surface of the substrate, which is conducive to enhancing the quality of the coating [14,15]. When the voltage exceeds 36 V, the droplets are prone to high-temperature oxidation and burning, and after cooling, oxide particles are formed and deposited in the coating, resulting in poor internal bonding of the coating and a decrease in the microhardness of the coating [16,17]. In the high-speed arc spraying process, the wire feeding rate is directly related to the current.…”

“…Under the load of the friction pair, the coating was constantly squeezed and scraped. The peeling and crack propagation of the coating were further aggravated [17,31]. It can also be seen from Figure 11d that some black areas appeared on the surface of the wear marks.…”