Properties of Al_2O_3 based nanostructured ceramic coatings on magnesium alloy surface by thermal spraying

Al2O3 based nanostructured ceramic coatings were prepared on the surface of magnesium alloy AZ31B by oxyacetylene flame spraying technology.XRD and SEM were used to analyze the composition and morphology of this composite ceramic coating.The thermal shock,compactness,wear properties and corrosion resistance of the composite ceramic coating were investigated.The results show that new phases of AlTi3,Al2TiO5 and so on are found in the nanostructured ceramic coatings.The structure of coatings become more dense and ceramic particles melting is better.The thermal shock,compactness,wear properties and corrosion resistance of nanostructured ceramic coatings by thermal spraying are significantly superior to that of micron-structured ones.Their thermal-shock times reaches about 40 times,which shows that the nanostructured ceramic coatings possess high bonding strength.After sealing with varnish,porosity is zero and the compactness and the corrosion resistance reach the best.