Microstructure and mechanical properties of hafnium carbide coatings synthesized by reactive magnetron sputtering

Hafnium carbide coatings with different carbon contents were synthesized in Ar-C(2)H(2) mixture by reactive magnetron sputtering. Energy-dispersive X-ray, X-ray diffraction, scanning electron microscopy, atomic force microscopy, and nanoindentation were employed to characterize their microstructure and mechanical properties. The effects of C(2)H(2) partial pressure on the composition, phase, microstructure, and mechanical properties of the coatings were investigated. The results show that hafnium carbide coatings can be synthesized at a low partial pressure of C(2)H(2). The single-phase HfC coating with columnar crystal and favorable mechanical properties is obtained when the proportion of C(2)H(2) partial pressure is only about 3.0% in the mixture, and the highest hardness and modulus are 27.9 and 255 GPa, respectively. The coating contains metal Hf and HfC phases and obtains low hardness under lower C(2)H(2) partial pressure. When the C(2)H(2) partial pressure is higher, the hardness and elastic moduli of acquired amorphous coatings decrease significantly.