Fig. 5

(a) Thickness values of the MAO and UMAO coatings generated under different conditions (n = 20). The use of ultrasound during the MAO process increased the thickness of the coatings. All data are expressed as means ± SD; * ─ statistically significant difference as compared to the MAO specimen in each group (p < 0.05). (b) Cross-section SEM micrographs of coatings of 68_450_n_300 – specimen after treatment with the lowest coating’s thickness value and 136_600_sin_300 – specimens after treatment with the highest coating’s thickness value.