Study On Preparation And Performance Of Aluminum-carbon Nanotube Composite Coating

Aluminum coating is a kind of coating has good protection performance, the surface of aluminum coating is rapidly oxidized, form a protective oxide film with thick, dense and strong bonding force. Aluminium and aluminium alloy coating has been applied in electronics, aerospace industry, and automobile industries. With the development of science and technology, people put forward higher requirements on the performance of the aluminum coating. The addition of nano particles can makes coating achieve unique physical and chemical properties, and makes the nano composite coating showed a lot of excellent performance. The addition of carbon nanotubes particles in the aluminum coating, can make the grain refinement in aluminum coating, improve the compactness and corrosion resistance of the coating, so the nano composite coatings on aluminum has a good application prospect.This paper obtained aluminum-carbon nanotube composite coating in organic electrolyte with the addition of carbon nanotubes based on the study on the electroplating of aluminum. The results and conclusions are as follows:(1) The effects of current density, time, temperature and stirring speed on the properties of composite coatings of aluminum-carbon nanotubes were investigated; the suitable process parameters have been obtained.(2) The effects of lithium aluminium hydride, aluminium chloride, carbon nanotubes, sodium citrate, texadecyl trimethyl ammonium Bromide on the electrodeposition of aluminum-carbon nanotube composite coatings were studied by single factor experiment. The optimal plating solution formula was determined by orthogonal experiment. Under the optimum process conditions and plating solution formula, the average thickness of the aluminum-carbon nanotube composite coating is 29.04μm, and the hardness is 125.31 HV. The hardness of aluminum-carbon nanotube composite coating was significantly higher than pure aluminum coating.(3) Observed the surface morphology of aluminum and carbon nanotubes composite coatings by SEM, we can find that aluminum and carbon nanotubes were co deposition. Compared with pure aluminum coating and aluminum carbon nanotube composite coating, the surface of aluminum-carbon nanotube composite coating is very rough, and carbon nanotubes are uniformly distributed in the coating. Analyzed composition of the aluminum-carbon nanotube composite coating by EDS, the results show that the composite coating is mainly composed of three elements C, Al, O, and the content of C element is about 5%. Aluminum and carbon nanotubes were co-deposited onto copper substrate. Detected the organizational structure of aluminum-carbon nanotubes coating by XRD, the results show that the peak of the composite coating is width than pure aluminum coating, the grain size of composite coating is small than pure aluminum coating. The binding force was evaluated by three kinds of test method-scratch test, bending test, and heating (cold) tests. The results show that the composite coating had not skin, shedding phenomenon in the three kinds of test conditions, the binding force of the composite coating is good.(4) Analysis the Tafel curve of coating in different corrosion medium, the results show that the corrosion resistance of aluminum-carbon nanotube composite coatings is superior than pure aluminum coating in neutral and acid medium,while in alkaline medium, the corrosion resistance of aluminum-carbon nanotube composite coatings is inferior than pure aluminum coating.