Corrosive environments cause severe damage to industrial equipment, potentially leading to corrosion of components, leakage of corrosive media, and even safety incidents. This study investigates protective coatings for cemented carbide cutting tools in industrial equipment. A gradient TiSiCN coating was deposited on high-speed steel surfaces using multi-arc ion plating. The microstructure and corrosion resistance of the composite TiSiCN coating under varying gas flow ratios were evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation testing, high-temperature friction and wear experiments, and an electrochemical workstation. Results indicate that the gradient TiSiCN coating primarily consists of TiC and TiCN phases, exhibiting preferred orientation on the TiCN (111) crystal plane. At a 5:5 gas flow ratio, the coating sample achieved a polarization resistance of 2.297 × 10⁵ Ω·cm², surpassing other ratios or single-layer TiSiCN coatings, demonstrating superior corrosion resistance. Therefore, when applying protective coatings to industrial equipment surfaces, it is essential to thoroughly understand both the coating materials and the coating process to effectively ensure the corrosion resistance of the equipment surfaces.

Protective coatings offer low cost, ease of application, high efficiency, and broad applicability, making them an effective method for safeguarding metal structures. This study simulates the electrochemical corrosion behavior of a composite coating (graphene/fluorocarbon coating) in seawater and evaluates its hardness, adhesion, and impact resistance. During simulation, polarization curves and AC impedance spectroscopy were employed to monitor the coating’s electrochemical corrosion and failure processes. Experimental results indicate that graphene provides an excellent barrier against corrosive media. The protective performance of the coating first increases and then decreases with increasing graphene content. At a content of 0.5% (mass fraction), the coating exhibits a corrosion current density of 2.366 × 10⁻¹⁰ A/cm², demonstrating the best corrosion resistance. Furthermore, the entire 360-hour immersion period was classified as the early immersion stage, indicating effective isolation against corrosive liquid penetration and optimal protective performance for the Q235 steel substrate. The FEVE-0.5%G coating exhibits moderate hardness, good adhesion, and erosion resistance, providing a certain level of protective efficacy.

To address corrosion issues in chemical machinery and equipment, ensuring the safety and reliability of chemical plant operations, this paper presents an effective anti-corrosion solution using “polymeric chemical materials” as an application example. Polypyrrole (PPy) offers advantages such as easy synthesis, film-forming capability, high conductivity, excellent stability, and environmental friendliness. By coating various metal and non-metal substrates with vanadium pentoxide (V₂O₅) sol-gel and employing the VPP method, PPy/V₂O₅ composite materials are synthesized under ambient temperature and pressure conditions. Structural characterization was performed using X-ray energy dispersive spectroscopy (XEDS) and Fourier transform infrared spectroscopy (FTIR). Corrosion resistance was evaluated through gravimetric weight loss and electrochemical testing. Results demonstrated no significant corrosion on the 1:1 PPy/V₂O₅ composite coating surface after 60 days of immersion in a 3.5 wt% NaCl solution. When characterizing the corrosion inhibition effect of the inhibitor through weight loss experiments and electrochemical testing, the incorporation of nano-SiO₂ enhanced the film’s corrosion resistance by strengthening the mechanical shielding effect of the coating and suppressing charge transfer during the corrosion reaction, thereby effectively protecting mechanical equipment.

Traditional corrosion prevention technologies such as electrochemical protection, corrosion inhibitors, and coatings can effectively mitigate metal corrosion issues. However, in recent years, this field has imposed increasingly stringent requirements beyond corrosion performance, demanding long-term protection, stability, and environmental adaptability for metals. To address these challenges, this study employs structural design to synthesize a series of novel carboxyl-functionalized polyarylenenitriles (CPENs) with varying molecular weights using bisphenol A, 2,6-dichlorobenzonitrile, and 2,6-dichlorobenzoic acid as raw materials. Performance testing and analysis of the CPEN coatings were conducted, including infrared analysis, stability, abrasion resistance, and acid/alkali corrosion resistance. Experimental tests on four metal substrates—steel, aluminum, copper, and magnesium—revealed that the presence of the coating shifted the corrosion potential toward the anodic direction compared to uncoated surfaces, while reducing the corrosion current density by one to two orders of magnitude. This demonstrates the coating’s effective application on various metal surfaces.

This study systematically investigated the effects of three types of surface modification techniques—chemical treatment, thermal treatment, and electrochemical treatment—on the adhesion and corrosion resistance of SiO\(_2\) protective coatings on TC4 titanium alloy substrates. Through multi-scale characterization, it was found that substrate roughness is positively correlated with coating adhesion. C\(_8\)HO\(_3\)Si chemical treatment (roughness 63 \(\mu\)m) and MAO treatment (62 \(\mu\)m) achieved the highest adhesion strengths of 8.01 MPa and 7.91 MPa, respectively, with both exhibiting 100% Type B interface failure (cohesive failure within the coating), indicating that the interface bonding strength exceeds the coating’s inherent strength. In contrast, H\(_2\)O\(_2\) treatment (roughness 16 \(\mu\)m) exhibited the lowest adhesion (2.57 MPa). Electrochemical testing revealed that C\(_8\)HO\(_3\)Si-treated samples had the most positive corrosion potential (-0.087 V), lowest corrosion current (4.3 nA/cm\(^2\)), and widest passivation range (0.131 V), demonstrating the best corrosion resistance. MAO treatment increased surface hardness to 417 HV (uncoated substrate: 204 HV), improving corrosion resistance by 51.08%. After 10 days of salt spray testing, the impedance of the C\(_8\)HO\(_3\)Si and MAO coating systems remained above 1.0 \(\mathrm{\times}\) 10\(^9\) \(\Omega\)·cm\(^2\), significantly outperforming FCS treatment (corrosion current: 30.7 nA/cm\(^2\)). XRD confirmed that MAO forms highly crystalline rutile-type TiO\(_2\) (characteristic peaks at 27.5\(\mathrm{{}^\circ}\) and 36.1\(\mathrm{{}^\circ}\)), while FCS generates a CaTiO\(_3\)/hydroxyapatite composite layer (peaks at 33.2\(\mathrm{{}^\circ}\) and 25.9\(\mathrm{{}^\circ}\)). The dense phase structure is key to enhancing protective performance. The synergistic optimization of substrate roughness, interfacial bonding, and passivation capability achieved by combining C\(_8\)HO\(_3\)Si chemical treatment with MAO electrochemical treatment provides an effective solution for the application of titanium alloy protective coatings in harsh environments.