In contrast to DLC (diamond like carbon) coatings, which are used millions of times, crystalline diamond coatings on steel have been almost non-existent in industrial applications so far, due to various problems during coating.
The Chair of Materials Science and Engineering for Metals at the Friedrich-Alexander University Erlangen-Nürnberg has succeeded in depositing adhesive hot-filament CVD diamond coatings on various particle-blasted steel materials and tools by using high temperature CVD interlayers (titanium nitride with boron doping at 1030°C) and gas quenching from the diamond heat in the hot-filament diamond coating process.
Since particle blasting produces a random, relatively undefined surface structure and hard blasting particles such as silicon carbide can accumulate in the steel surface, in the IGF project 17/11 "Adhesive CVD diamond coatings on sliding rings made of steel" the TU Chemnitz is producing surface structures with defined structure distances (20 µm to 100 µm) and structure depths (4 µm to 10 µm) as a substitute for particle blasting by ultrasonic-assisted mechanical surface processing methods. For the first time ever thick diamond layers of up to 15 µm can be deposited on such structured steel sliding rings with an outer diameter of 55 mm.