Ta-C coating is a non-hydrogen carbon element coating, also known as tetrahedral amorphous diamond-like coating. It has a high ratio of sp to sp2 bonds, with sp3 diamond content ranging from 65% to 85%, and a Vickers hardness of up to 5000-7000 HV. Ta-C exhibits some transparency, causing the workpiece to display a rainbow color due to light interference when the coating thickness is less than 1 µm. As the coating thickness increases, the color transitions to grayish black. The excellent adhesion resistance and high hardness of Ta-C coating make it play a significant role in the mold and cutting tool industries.