Selective growth of oxidation coating was observed with Al18B4O33 crystal whisker as reinforced phase） on Mg matrix composite Al18B4O33w/AZ91 （a composite when this composite was treated by microarc oxidation （MAO...Selective growth of oxidation coating was observed with Al18B4O33 crystal whisker as reinforced phase） on Mg matrix composite Al18B4O33w/AZ91 （a composite when this composite was treated by microarc oxidation （MAO） technique, and then the role of Al18B4O33 whisker in the process of MAO was analyzed. The protective properties of MAO coating also were investigated. Scanning electron microscopy （SEM） was used to characterize the existing state of Al18B4O33 whisker in MAO process and the microstructure of MAO coating. Corrosion resistance of the bare and coated composite was evaluated by immersion corrosion test and potentiodynamic polarizing test. Wear resistance of MAO coating was investigated by a ball-on-disc friction and wear tester. The results showed that sparking discharge did not occur on Al18B4O33 whisker and the whisker existed in the coating as a heterogeneous phase when MAO coating grew on the composite; then the whisker would be covered gradually with growing thick of the coating. Corrosion current density of the coated composite was decreased by 4 orders of magnitude compared with that of the uncoated composite; excellent corrosion resistance was closely related to the compact whisker-coating interface since Al18B4O33 whisker did not induce structural defects. The coating also exhibited high wear resistance and a slight adhesive wear tendency with bearing steel as its counterpart material.展开更多
基金National Nature Science Foundation of China(51201008)the Fundamental Research Funds for the Central Universities(FRF-TP-12-166A)+1 种基金the General(2011M500241)Special Financial Grants from the China Postdoctoral Science Foundation(2012T50044)
基金supported by the National Natural Science Foundation of China(No.51001036)the Fundamental Research Funds for the Central Universities(Nos. HEUCFR1021 and HEUCF201210001)
文摘Selective growth of oxidation coating was observed with Al18B4O33 crystal whisker as reinforced phase） on Mg matrix composite Al18B4O33w/AZ91 （a composite when this composite was treated by microarc oxidation （MAO） technique, and then the role of Al18B4O33 whisker in the process of MAO was analyzed. The protective properties of MAO coating also were investigated. Scanning electron microscopy （SEM） was used to characterize the existing state of Al18B4O33 whisker in MAO process and the microstructure of MAO coating. Corrosion resistance of the bare and coated composite was evaluated by immersion corrosion test and potentiodynamic polarizing test. Wear resistance of MAO coating was investigated by a ball-on-disc friction and wear tester. The results showed that sparking discharge did not occur on Al18B4O33 whisker and the whisker existed in the coating as a heterogeneous phase when MAO coating grew on the composite; then the whisker would be covered gradually with growing thick of the coating. Corrosion current density of the coated composite was decreased by 4 orders of magnitude compared with that of the uncoated composite; excellent corrosion resistance was closely related to the compact whisker-coating interface since Al18B4O33 whisker did not induce structural defects. The coating also exhibited high wear resistance and a slight adhesive wear tendency with bearing steel as its counterpart material.
