CO addition in low-pressure chemical vapour deposition of medium-temperature TiCxN1-x based hard coatings

► Synthesis of single-phase TiCN(O) coatings via chemical vapour deposition. ► Structure modification from coarse grains to sub-micron grains due to CO addition. ► High resolution analysis reveals defects due to incorporated oxygen. ► Optimized CO addition gives maximum in hardness and minimum in tensile stress.