A comparative study on thermally sprayed alumina based ceramic coatings

Aluminium oxide is relatively cheap material, abundant almosteverywhere and therefore it is widely used for thermal sprayapplications. Various alumina based powder containing 13 wt. Titania, two different 40 wt.% Zirconia and three differentcompositions of alumina-zirconia-chromia were deposited byatmospheric plasma spraying (APS) and high power plasma spraying(HPPS). The coatings obtained were evaluated by optical microscopy,microhardness measurements, X-ray diffraction and porositymeasurements. Moreover, abrasion and friction wear resistance wereevaluated by using Pin-on-Disc machine. Microhardness values of APScoatings are relatively high as compared to HPPS coatings except inalumina-zirconia-chromia coatings. HPPS have higher hardness values.APS coatings are much coarser and show higher porosity values thanHPPS coatings. The best wear/friction behaviour exhibited coatingAl2O3-40 wt.% ZrO2 that deposited from agglomerated andsintered powder type.