Hardide coatings are free from cobalt, this is an important advantage for nuclear applications where cobalt-containing alloys and hardfacing can be hazardous.
Even corrosion- and wear-resistant Co alloys produce small amounts of Co-containing debris which can be carried with the coolant fluids into the reactor zone. Neutron irradiation can produce radioactive Co60 isotope, which is a strong emitter of highly penetrating gamma-radiation with a half-life of 5.27 years. Highly radioactive Co60 can be absorbed from the coolant flow into the surface of the primary system components making them a source of occupational radiation exposure. Attempts to develop cobalt-free hardfacing with good tribological properties and enhanced resistance to wear, erosion, corrosion and also cavitation started in the 1960s and are still continuing today. Hardide coatings are a good solution to this problem.
Hardide CVD coating on cemented carbide