MICROSTRUCTURES AND ABRASIVE PROPERTIES OF THE OXIDE COATINGS ON Al6061 ALLOYS PREPARED BY PLASMA ELECTROLYTIC OXIDATION IN DIFFERENT ELECTROLYTES

摘要

Al_2O_3 coatings were prepared on T6-tempered Al6061 alloys substrate under a hybrid voltage (AC 200V-60Hz and DC 260V value) by plasma electrolytic oxidation (PEO) in 30 min. The effects of different electrolytes on the abrasive behaviors of the coatings were studied by conducting dry ball-on-disk wear tests. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the coating microstructure. XRD analysis results show that the coatings mainly consist of α- and γ-Al_2O_3, and some mullite and AlPO_4 phase in Na_2SiO_3 and Na_3PO_4 containing electrolytes, respectively. The wear test results show that the coatings which were PEO-treated in Na_3PO_4 containing electrolyte presented the most excellent abrasive resistance property.