| In this paper, we used the6061aluminum alloy as the substrate to produce theceramic coatings on the substrate surface, which through the homemade WH-1micro-arcoxidation equipment. The characteristics of the ceramic coatings produced on6061aluminum alloy in a composite electrolyte with silicate and phosphate were researched. Inorder to solve the problems of growth slow, poor quality and high energy consumption themid to late periods, the ultrasonic effect was introduced in the micro-arc oxidation process.Meanwhile, we researched the effect of ultrasonic on the ceramic coatings in the wholestage and each different stage.The results showed that the ceramic coatings produced by plasma electrolyticoxidation is attached with the substrate closely and honeycomb structure. The ceramiccoatings produced in a composite electrolyte with silicate and phosphate were composedof α-Al2O3、γ-Al2O3、3Al2O3·2SiO2and little AlPO4. The residual stress is compressivestress in the ceramic coatings, and it increases first then decrease with the treatment timeincreasing. The external conditions of heat treatment and ultrasonic oscillation can changethe distribution of residual stress.The introduction of ultrasonic changed thevoltage-current curve trend and increased the ceramic coating thickness. The arcingvoltage decreased with the increase of ultrasonic power. The ultrasonic action did notchange the phase composition of ceramic coatings, but promoted the development ofphase transformation which the content of α-Al2O3increased obviously. It is alsoimproved the hardness and corrosion resistance of the ceramic coatings. For the ultrasonicintroduced in the initial stage, the element contents of Si and P are highest. Meanwhile, thecompactness and corrosion resistance are also the best which are increased3.6times thanthat in the final period. For the ultrasonic introduced in the final stage, the coatingthickness is the thickest and the content of α-Al2O3phase is the highest. |
PDF Full Text Request