Effects of Duty Cycle and Pulse Frequency on the Microstructure and Mechanical Properties of TiAlN Coatings

Abstract

This paper presents the effects of pulse plasma parameters such as duty cycle and pulse frequency on the properties of TiAlN coatings deposited by asymmetric bipolar pulsed DC magnetron sputtering systems. The results show that, with decreasing duty cycle and increasing pulse frequency, the coating morphology changes from a columnar structure to a dense structure with finer grains. Pulsed sputtered TiAlN coatings showed higher hardness, higher residual stress, and smaller grain sizes than did DC prepared TiAlN coatings. Moreover, residual stress and nanoindentation hardness of pulsed sputtered TiAlN coatings increased with increasing pulse frequency. Meanwhile, the surface roughness decreased continuously with increasing pulsed DC frequency up to 50 kHz.

Crystal Structure, Microstructure and Mechanical Properties of NbN Coatings Deposited by Asymmetric Bipolar Pulsed DC Sputtering

“…ransition metal nitride coatings are being used for protection of substrates in extreme environments such as aircraft and jet engines, since they have not only high-temperature hardness, resistance to thermal and mechanical fatigue, strong adherence, chemical stability and low friction coefficient but also excellent hardness or durability. [1][2][3][4] Among them, NbN coatings have excellent hardness or durability and are produced by diversified coating methods owing to such characteristics. Recently, not only dc (direct current) sputtering but also coating equipment such as hybrid sputtering and ion plating are being utilized.…”