Ni-p-cr Based Nanocomposites Preparation And Properties

Aiming to obtain new materials with excellent anticorrosion properties in seawater and microbial environment, a series of composite deposits were prepared from plating solution with Cr³⁺ by electrodeposition. The prepared electrodeposits were amorphous Ni-P-Cr coating, amorphous Ni-P-Cr/micro-TiO₂ coating, amorphous Ni-P-Cr/nano-TiO₂ coating and amorphous Ni-P-Cr/nano-ZrO₂ coating. The preparing process, structure and property of these coatings were investigated comprehensively and some valuable results were obtained. The main contents of this thesis are: A) Ni-P-Cr coating was prepared by electrodeposition and the surface morphology, elements and crystalline structure of the prepared Ni-P-Cr coating were investigated with SEM, EDX and XRD respectively. The main factors of the preparing process, structure and property of the Ni-P-Cr coating were discussed. B) Ni-P-Cr/micro-TiO₂, Ni-P-Cr/nano-TiO₂ and Ni-P-Cr/nano-ZrO₂ coatings were prepared by elcetrodeposition according to the optimum preparing process of amorphous Ni-P-Cr coating. The surface morphology, elements and crystalline structure of the prepared coatings were investigated. The main factors of the preparing process, structure and property of the prepared coatings were discussed. C) The anticorrosion properties of all the coatings and A3 steel were studied by using polarization curve in simulated seawater(3.5%NaCl solution) and electrochemical impedance spectroscopy(EIS) in culture medium in the presence of sulphate reducing bacteria(SRB).The anticorrosion properties of all these coatings were compared with each other and the results showed that the E_corr of the Ni-P-Cr/nano-TiO₂ coating was more positive-going than others' and its i_corr was the smallest among this series of coatings in simulated seawater. The Ni-P-Cr/nano-TiO₂ coating was passivated and had largest polarization value in blank culture medium. The Ni-P-Cr/nano-TiO₂ coating also showed excellent passivation behavior and had not been corroded in culture medium in the presence of SRB, whereas the other coatings and A3 steel were severely corroded under the same condition. All the facts listed above have proved the excellent anticorrosion property of Ni-P-Cr/nano-TiO₂ coating in simulated seawater and culture medium in the presence of SRB.