Ta-C coating is a hydrogen-free carbon element coating, also known as tetrahedral amorphous diamond-like coating. It has a high sp/sp2 bond ratio, with sp3 diamond content ranging from 65% to 85%, and a Vickers hardness of up to 5000-7000 HV. Ta-C exhibits some transparency, and when the coating thickness is less than 1 micrometer, the workpiece will display a rainbow color due to light interference. As the coating thickness increases, the color changes to gray-black. Its excellent adhesion resistance and high hardness make Ta-C play a crucial role in the mold and cutting tool industries.