For improving the corrosion resistance of 40Cr substrate, an organic/inorganic composite coating, BTESPT/KH560 bilayer silane composite film, was prepared on substrate surface. And the corrosion resistance of the bilayer film was enhanced by filling dopamine-modified boron nitride (mBN) into the second film. Electrochemical test was carried out to verify the corrosion inhibition efficiency of the coatings. Scanning electron microscope (SEM) was employed to observed the surface morphology and cross sections of films. The hydrophobicity of films was tested through contact angle test. Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to analyze the structure and composition of films. At last, the corrosion inhibition mechanism of films was discussed. The results indicated that BTESPT/KH560 silane film can effectively prevent metal from corrosion, and the corrosion inhibition efficiency was improved to 99.87% by filling mBN. BTESPT/KH560 silane film can be prepared on metal surface smoothly. Thicker film and better hydrophobic properties were obtained by filling mBN. Besides, the hydroxyl group on mBN reacted with silane to form Si-O-B bond in mBN/BTESPT/KH560 film. Silane was connected to silane by Si-O-Si bonds and to metal substrate by Si-O-Fe bonds, achieving the stable adhesion of bilayer silane film on metal surface.
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