Structural characteristics and outward-inward growth behavior of tantalum oxide coatings on tantalum by micro-arc oxidation

► The coatings are produced on pure tantalum by micro-arc oxidation. ► The coatings are porous and can tightly bond to the substrates. ► The growth of the coatings exhibits outward-inward growth characteristics. ► Similar outward-inward growth characteristics exist with different applied voltages.