Industrial feasibility of the nitrocoat process

The recently developed nitrocoat process consists of a plasma nitriding step and a subsequent hard coating deposition step, where both steps are performed in a physical vapour deposition (PVD) apparatus. For good adhesion between the nitrided zone and the PVD coating the presence of iron nitrides at the surface of the nitrided steel is detrimental. The aim of the nitrocoat process is to prevent the formation of iron nitrides during the nitriding treatment. Then an intermediate polishing process can be omitted. The feasibility of the nitriding process for industrial use was investigated. In a fully loaded PVD machine the plasma nitriding process was successfully applied using an industrially relevant background pressure. For steels very different in composition, a single set of nitriding conditions was obtained for nitriding without the formation of iron nitrides. All the steels showed satisfactory hardness increase due to nitriding under these conditions. Consequently, nitrocoat treatment on different steel types in a single batch is possible.