In this paper, the C₃N₄ coating was prepared on AISI 304 stainless steel surface with N-N dimethylformamide (DMF) and KCl solution as electrolyte by electrochemical deposition method. The effects of DMF concentration on its composition, mechanical properties and wear resistance were investigated. The effects of DMF on the composition and mechanical properties of C₃N₄ coating were investigated by scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS), X-ray diffractometer (XRD), Vickers hardness tester and friction and wear tester. The results show that the C₃N₄ coating was successfully prepared using DMF. With the increase of DMF concentration, the surface particle size of the C₃N₄ coating gradually decreased, and the deposition rate of the C₃N₄ coating showed a trend of first increasing and then decreasing. The thickness of the C₃N₄ film deposited at 50%DMF ratio could reach 20 μm, and the binding force of the film base reached HF1 level. The coating mainly contains C₃N₄ phase, accompanied by a small number of impurity phases such as Fe₃O₄, CrN, Cr₃C₂, FeN_x, etc. The C element mainly exists in the C=O, C-N, C-C and C-Cr bonds, and the N element mainly exists in the N-C sp², N-C sp³ and N-CR bonds. The surface hardness of the coating can reach up to 1380 HV0.05, which is three times that of the untreated material. The friction coefficient of C₃N₄ film can be reduced to about 0.3 and the wear rate is the lowest 8.75×10^-9 g∙N^-1∙m^-1, which is more than 7 times lower than that of untreated material. The wear failure forms of C₃N₄ film are mainly fatigue wear, abrasive wear and oxidation wear. During the deposition of the coating, DMF molecules in the solution are converted into NH₂(CH₃)₂ energy molecules, which are adsorbed into CH₃NH₂ activated molecules at the activation reaction point on the surface of the material, and the activated molecules react to produce C₃N₄ films and other products.
 

Electrochemical deposition; C3N4 coating; Stainless steel; Friction and wear; Reaction mechanism