Preparation of Ni-TiN Nanocomposite Coatings and Their Application to Copper Electrode Plates for Electrostatic Spray Nozzles
Electrostatic spraying improves pesticide deposition by charging droplets, but copper electrode plates undergo electrochemical corrosion and surface oxidation in humid, weakly acidic, pesticide-laden environments, reducing conductivity and charge transfer efficiency. Ni-TiN nanocoatings with varying TiN concentrations were electrodeposited on T2 copper cathodes using a nickel anode at a cathode-to-anode area ratio of 1:2 and 60 mm electrode gap. TiN nanoparticles averaged 43 nm. Scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, microhardness testing, contact angle measurement, electrochemical workstation, and salt spray testing characterized the coatings. TiN addition refined the cellular Ni structure, reduced porosity, and produced only face-centered cubic Ni and TiN phases without intermetallic or oxide impurities. At 6 g/L TiN, the coating reached 120 μm thickness, 743.62 HV microhardness, Ni and TiN average grain sizes of 67.28 nm and 35.84 nm, corrosion potential of −0.23 V versus SCE, corrosion current density of 6.07×10−9 A/cm2, interfacial contact resistance of 6.4 mΩ·cm2, and contact angle of 132.82°. After 24 h continuous salt spray, only minor pits appeared without spalling or loosening. The results demonstrate that optimized TiN concentration enhances corrosion resistance, hardness, hydrophobicity, and electrical conductivity, providing a reference for protecting electrostatic spray nozzle copper plates.