Ni–Co and Ni–Co/ZrO 2 composite coatings have been synthesized via a single-step direct current (DC) electrodeposition route as a protective coating. The influences of electrodeposition current density, time and ZrO 2 concentration on structural, composition and properties of Ni–Co coating were investigated. All coatings present compact, crack-free and nodular-like morphology in a nanocrystalline structure. Some aggregations still exist in the coating. The preferred orientation of these coatings changed from (200) to (111) texture with a fcc structure . The amount of Co in Ni–Co matrix slightly decreases as current density and time increases. The Co and ZrO 2 content in Ni–Co/ZrO 2 matrix increase with the increasing of ZrO 2 concentration in bath. Less than 60 min is beneficial for low roughness of Ni–Co/ZrO 2 coating. Current density, deposition time and ZrO 2 embedded in metallic matrix affect the hardness of Ni–Co alloy. Ni–Co/ZrO 2 coating has enhanced hardness compared to Ni–Co ones. Although they might not exhibit the best corrosion resistance in the initial immersing stage, Ni–Co/ZrO 2 composite coating obtained at 2 – 4 A dm −2 with 5–10 g L -1 ZrO 2 presents the better corrosion resistance and desirable performance stability during the long-term immersion process in aggressive media. The Ni–Co/ZrO 2 coating exhibits promising advantages as a protective coating.
Xiao Han,Ziqi You,Yufeng Liu,Ruina Ma,Yongzhe Fan,An Du,Xue Zhao,Mingxu Yang
In this study, superhydrophobic coatings characterized by micro- and nanostructures were fabricated using a simple spraying method. The water contact angle of the ETFE-ZrO 2 composite coating achieved a maximum of 157.3° after three spraying applications, with a mass ratio of ethylene-tetrafluoroethylene copolymer (ETFE) to modified ZrO 2 particles established at 1:1. This coating had good corrosion resistance, as demonstrated by a reduction in corrosion current density to 2.162 × 10 −6 A/cm 2 , which is an order of magnitude lower than that of Q345 steel. Following immersion in a 3.5 wt% NaCl solution for 72 h, the superhydrophobic coatings retained their hydrophobic properties. Furthermore, these coatings demonstrated good chemical stability, maintaining a water contact angle >150° across a pH range of 3 to 12. Additionally, the coatings exhibited effective self-cleaning properties and photocatalytic effects. The rapid fabrication of these coatings presents significant advantages for the development of large-area, superhydrophobic, and self-cleaning surfaces, as they do not require complex modifications or reactions.
Lu Zhu,Xuanru Ren,Xiaohong Wang,Xueqin Kang,Ruixin Zheng,Peizhong Feng
Spent MoSi 2 heating elements, which worked in the industrial electrical furnace at high temperature, were crushed into powders and reused as coating raw materials. ZrO 2 was added into spent MoSi 2 powders to fabricate MoSi 2 -ZrO 2 coatings on niobium by spark plasma sintering, and the microstructure and oxidation behavior of the coatings at 1500 and 1700 °C were explored. The results showed that cracks exist in MoSi 2 coating while ZrO 2 -containing coatings are crack-free with the formation of (Mo,Nb) 5 Si 3 diffusion layer after SPS, indicating good metallurgical bonding. After oxidation at 1500 °C for 20 h, the lowest mass gain is obtained by MoSi 2 -30ZrO 2 coating. SiO 2 and ZrSiO 4 are formed on the composite coatings at elevated temperature, which improves the high-temperature oxidation resistance. After oxidation at 1700 °C for 60 min, the oxide scale of MoSi 2 -30ZrO 2 coating is dense without any voids or cracks, demonstrating better high-temperature oxidation resistance than that of single MoSi 2 coating.
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