Structural investigation of Al2O3 coatings by PECVD with a high deposition rate

The deposition of alumina on thermal barrier coatings can effectively avoid hot corrosion and increase durability. Al2O3 coatings were prepared on an yttria-stabilized zirconia (YSZ) substrate by plasma chemical vapor deposition (CVD). The effects of microwave power (P-M) and total pressure (P-tot) on the crystalline phase and microstructure of Al2O3 coatings were investigated, and the effect of the mechanism on the deposition rate was also analyzed. The alpha-Al2O3 coatings with a needle-like microstructure were formed at a higher P-M and P-tot, whereas the gamma-phase coatings exhibited a cauliflower-like microstructure at a lower P-M and P-tot. A maximum deposition rate (R-dep) of 58 mu mh(-1) was obtained, which is significantly higher than those of conventional CVD methods.