Quantitative analysis of pores in plasma-sprayed ZrO₂ coatings

Two graded thermal barrier coatings of different structures were prepared by plasma spraying. The porosity, size and shape of pores of excessive-ceramic areas in two coatings were analyzed quantitatively by quantitative analysis technology. The results show that the porosities of excessive-ceramic areas in two coatings are similar and it is the greatest at the interface which is less than 6%, the probability distributions of pore size in two coatings are resemblance to each other, pores of diameters from 1 um to 10 um are the most whose percentage is between 72% and 80%, the second are pores of diameter less than 1 um whose percentage is from 20% to 25%, the fewest are pores of diameter more than 10 um with percentage from 0.2% to 4%, the pores shape distributions in two coatings are close too, pores of same axes have the greatest percentage which is from 82% to 87%, second are pores of different axes whose percentage is between 13% and 17%, the fewest are oblate pores with percentage from 0.1% to 4%. It shows that the coating structure has no effect on the pore of excessive-ceramic areas.