| The micro-arc oxidation(MAO) technique is used on aluminum, magnesium and titanium metal surface and the ceramic coating has high hardness, fine corrosion resistance and wear resistance. In this paper, aluminum alloy was to deal with home-made micro-arc oxidation equipment. The additives like nano-TiO2, the mixed additives of nano-Zn O + nano-TiO2, La(NO3)3 + nano-TiO2 were added into the silicate electrolyte under constant voltage, and the effects of these additives formed on the ceramic coatings were studied. Taking the TT230 thickness tester measures the thickness of MAO film and taking the MHV-1000 micro Hardness Tester measures the surface hardness of the coatings. The conductivity of electrolyte was measured by the DDS-11 A conductivity meter. Taking the CR-4032 measuring instrument measures the surface roughness of the coatings. The corrosion resistance was measured by the VSP work station. The wear resistance was measured by the MMS-2A friction and wear tester. The binding force of the film surface was tested by the WS-97 scratch coating adhesion tester. With the help of the KYKY2800 B scanning electron microscope(SEM) and its’ attached Energy Disperse Spectrometer(EDS) and X-ray diffraction(XRD), the surface morphology and the elemental distribution on micro region of the surface and the element distraction on the surface of the film were obtained and the phase composition of the films were detected. The results are obtained by analyzing the experimental data.(1) The film has nicer comprehensive properties by adding nano-TiO2 additive in the silicate system when the concentration of nano-TiO2 is 2-4 g/L. The thickness of the coating is 59-63μm and the hardness is 450-510 HV. It improves the corrosion resistance and wear resistance and it makes the binding force of the film perfect. The phase composition of the coating is Al、α-Al2O3、γ-Al2O3 and AlTi.(2) The film has nicer comprehensive performance by adding nano-TiO2 + nano-ZnO mixed additive in the silicate system when the concentration of nano-TiO2 is 4 g/L and the concentration of nano-ZnO is 2g/L. The thickness of the coating is 52μm and the hardness is 692 HV. The phase composition of the coating is made of Al,α-Al2O3,γ-Al2O3,Al3 Ti and Zn0.6Ti0.4.And the performance of coating with 3g/L nano-TiO2 and 1g/L nano-Zn O is less than the coating of 3g/L nano-TiO2 and 1g/L nano-ZnO.(3) The film has nicer comprehensive performance by adding 3g/L nano-TiO2 + 0.5g/L La(NO3)3 mixed additive in the silicate system. The thickness of the coating is 71μm and the hardness is 689 HV. The phase composition of the coating is made of Al, α-Al2O3, γ-Al2O3, Rutile and SiO2.Al in all, aluminum alloy was processed with home-made micro-arc oxidation equipment. Compared with the coating fabricated on aluminum alloy in the silicate electrolyte, the properties of the coating has been improved after adding the additive of nano-TiO2, the mixed additives of nano-ZnO + nano-TiO2 and La(NO3)3 + nano-TiO2. |
PDF Full Text Request