Deposition of Coating to Protect Waste Water Reservoir in Acidic Solution by Arc Thermal Spray Process

Abstract

The corrosion characteristics of 304 stainless steel (SS) and titanium (Ti) coatings deposited by the arc thermal spray process in pH 4 solution were assessed. The Ti-sprayed coating exhibits uniform, less porous, and adherent coating morphology compared to the SS-sprayed coating. The electrochemical study, that is, electrochemical impedance spectroscopy (EIS), revealed that as exposure periods to solution were increased, the polarization resistance (Rp) decreased and the charge transfer resistance (Rct) increased owing to corrosion of the metallic surface and simultaneously at the same time the deposition of oxide films/corrosion on the SS-sprayed surface, while Ti coating transformed unstable oxides into the stable phase. Potentiodynamic studies confirmed that both sprayed coatings exhibited passive tendency attributed due to the deposition of corrosion products on SS samples, whereas the Ti-sprayed sample formed passive oxide films. The Ti coating reduced the corrosion rate by more than six times compared to the SS coating after 312 h of exposure to sulfuric acid- (H2SO4-) contaminated water solution, that is, pH 4. Scanning electron microscope (SEM) results confirmed the uniform and globular morphology of the passive film on the Ti coating resulting in reduced corrosion. On the other hand, the corrosion products formed on SS-sprayed coating exhibit micropores with a net-like microstructure. X-ray diffraction (XRD) revealed the presence of the composite oxide film on Ti-sprayed samples and lepidocrocite (γ-FeOOH) on the SS-coated surface. The transformation of TiO and Ti3O into TiO2 (rutile and anatase) and Ti3O5 after 312 h of exposure to H2SO4 acid reveals the improved corrosion resistance properties of Ti-sprayed coating.

Application of Arc Thermal Spray Process in Corrosion Protection of Steels and Electromagnetic Pulse Shielding

“…Therefore, these samples show greater cathodic and anodic current density. In another studies, Lee et al have found that Ti coating is the exhibiting better corrosion resistance that 316L SS coating at pH 4 due to formation of rutile and anatase phase as the passive film (Lee et al, 2018). The schematic representation as shown in Figure 15 depicts the formation of passive film on the stainless steel coating surface in inner surface of waste water reservoir (Lee et al, 2016b).…”

Electromagnetic Shielding Performance of Different Metallic Coatings Deposited by Arc Thermal Spray Process

“…The Cu, Cu-Zn, and Cu-Ni coating was deposited onto the smooth steel substrate by the arc thermal spray process. In the arc thermal spray process, twin wires were melted at 30 V and 200 mA on arcing point and with the help of compressed air on 7.5 bars, the molten metal particles are propelled, resulting in deposition of coating by keeping the substrate away from the spray gun on 15–20 cm as described in our earlier publications [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]. The deposition of Cu coating was carried out by twin wires of Cu while for Cu-Zn and Cu-Ni, one wire (wire-1) was Cu and another (wire-2) was Zn (Cu-Zn coating) and Ni (Cu-Ni coating) as described in Table 1 .…”

Electromagnetic Shielding Performance of Carbon Black Mixed Concrete with Zn–Al Metal Thermal Spray Coating

“…The arc thermal metal spraying method (ATMSM) was used to address the problem of metal plate in construction for existing shielding facilities owing to the cost effectiveness. In the arc thermal metal spraying method, a metal wire rod is coming out from the nozzle of a spray gun that blows compressed air, and is dispersed and cooled on the surface of the specimen to be coated [14,[28][29][30][31][32][33][34][35][36][37]. Subsequently, the specimen after spraying is allowed to quench, solidify, and laminate.…”