AbstractCarbon steel coatings can be employed for hardfacing mechanical components used in moderately aggressive wear environments, provided they are sufficiently hardened by retained carbon. However, when thermal spraying using compressed air as the atomising gas, properties of carbon steel coatings are degraded by carbon loss through oxidation and oxide inclusions. It is shown that the physical and mechanical properties of these coatings can be greatly improved by spraying with inexpensive nitrogen produced on site by pressure swing adsorption or membrane separation, without the cost penalties incurred when using pure nitrogen. In some circumstances, such coatings can be used to replace more expensive alloy hardfacing layers.