Aihua Yi

The integration of semiconductive nano-ZnO into a Ti/Zr-based solution has facilitated the development of a conductive coating on aluminum alloy surfaces. A comprehensive characterization of the coating's morphology, microstructure, electrical conductivity, and corrosion resistance was conducted utilizing a suite of analytical techniques, including SEM, FIB-SEM, EDS, XPS, UV-vis, FTIR, and an electrochemical workstation. Significantly, the electrical contact resistance (ECR) of the coating experienced a substantial decrease when subjected to a pressure of 200 psi, plummeting from 0.1907 Ω in⁻² in the absence of nano-ZnO to 0.0621 Ω in⁻² with the inclusion of nano-ZnO. Concurrently, the band gap of the coating was observed to diminish from 3.189 eV without nano-ZnO to 2.708 eV with nano-ZnO, indicating improved semiconductor properties. The coating exhibited a three-layer structure consisting of a substrate-close layer of nano-ZnO, a middle layer composed of Na₃AlF₆ crystals, and an outermost layer comprising ZnO and metal–organic complexes. The incorporation of nano-ZnO induced a striking morphological transition from a pebble-like to a cubic structure, along with a notable change in the coating's color. These findings collectively demonstrate the transformative impact of nano-ZnO on the multifaceted attributes of the conversion coating, endowing it with superior electrical characteristics.

Conductivity chromium‐free conversion coatings on aluminum substrates were achieved by utilizing Na ₂ SnO ₃ and Mo/Ti solutions. The composition and morphology of the coatings were characterized using XPS, SEM, EDS, AFM, and Raman spectroscopies. The corrosion behavior of the coatings in 3.5‐wt% NaCl solution was investigated through a dynamic potential polarization method and EIS analysis. Mott–Schottky and UV–Vis analyses were used to determine the semiconductor properties of the coatings, including carrier concentration and band gap. The results revealed that the main components of the coating were Al ₂ O ₃ , SnO ₂ , MoO ₃ , and MoO ₂ and the coating presented a double‐layer structure, including a transition layer close to the substrate and a compact layer on the surface. The coating also exhibited the properties of a p‐type semiconductor. The electrical contact resistance value of adding Na ₂ SnO ₃ decreased from 0.4331 to 0.1343 Ω/in ² (in 200 psi), while the band gap decreased from 2.281 to 2.232 eV.

Aluminum alloys with low-weight property are promising structure materials for sports equipment. Alloying element-rich second-phase particles create the risk of localized corrosion and result in failure of sports equipment. Chromate conversion coatings as conventional and successful surface treatments were employed to provide a thin but compact film against corrosion. However, chromate species were toxic and carcinogenic for human beings and this process has been highly restricted. In this sense, alternative processes such as trivalent chromium conversion coating with low environmental risk require better corrosion-resistant performance compared to chromate conversion coating. In addition, the closed-loop system of the chromate electroplating process has been used in Europe and the United States. This is also a sustainable process for surface treatment of aluminum alloys applied in sports equipment. The present paper aims to summarize the methods and types of different aluminum alloy surface treatments and compiles the effects of various surface treatments on the corrosion resistance of aluminum alloys. The eco-friendly application of aluminum alloys in the field of sports equipment may be facilitated in the future.

A novel glass-ceramic coating was applied onto the 1Cr11Ni2W2MoV stainless steel. The oxidation and corrosion behaviors of coated and uncoated steels were comparatively investigated in air and in the presence of NaCl + Na₂SO₄ eutectic deposits at 650 °C, respectively. Protective scales formed on the surface of stainless steel prevented the severe oxidation of the alloy. Catastrophic hot corrosion occurred on the steel when a salt film was attached, producing loose iron oxide layers and internal corrosion zone. The glass-ceramic coating acted as a barrier that effectively hindered the invasion of corrosive species during the oxidation and hot corrosion tests.