Structural and Mechanical Properties of Ti-W-N Thin Films by Dual Unbalanced Magnetron Sputtering

Abstract

Ti-W-N thin films grown on Si (100) and AISI D2 steel substrates had been deposited by a d.c. magnetron sputtering with pure Ti and W targets in a mixture of Ar and N2 plasma. The nitrogen partial pressure was varied from 0% to 9% of total gas. All Ti-W-N films were formed in solid solution with determination by x-ray diffractrogram analysis. A strong preferred orientation TiN(111) was detected. Their mechanical properties were studied using nanoindentation with Berkovich tip. An increase in hardness was observed with increasing nitrogen partial pressure. The optimum protective coating for plastic deformation was Ti-W-N film grown at 9% nitrogen partial pressure. Chemical bonding of Ti-W-N films was investigated by x-ray photoelectron spectroscopy. Binding energy analysis showed that N was mainly in TiN and W2N. The corrosion behavior was studied in variation of nitrogen partial pressure. Ti-W-N films deposited on steel at low nitrogen partial pressure showed excellent corrosion resistance in NaCl solution.