Nanoindentation and atomic force microscopy measurements on reactively sputtered TiN coatings

Abstract

Titanium nitride (TiN) coatings were deposited by d.c. reactive magnetron sputtering process. The films were deposited on silicon (111) substrates at various process conditions, e.g. substrate bias voltage (V B ) and nitrogen partial pressure. Mechanical properties of the coatings were investigated by a nanoindentation technique. Force vs displacement curves generated during loading and unloading of a Berkovich diamond indenter were used to determine the hardness (H) and Young's modulus (Y) of the films. Detailed investigations on the role of substrate bias and nitrogen partial pressure on the mechanical properties of the coatings are presented in this paper. Considerable improvement in the hardness was observed when negative bias voltage was increased from 100-250 V. Films deposited at |V B | = 250 V exhibited hardness as high as 3300 kg/mm 2 . This increase in hardness has been attributed to ion bombardment during the deposition. The ion bombardment considerably affects the microstructure of the coatings. Atomic force microscopy (AFM) of the coatings revealed fine-grained morphology for the films prepared at higher substrate bias voltage. The hardness of the coatings was found to increase with a decrease in nitrogen partial pressure.

Structural and mechanical properties of reactively sputtered TiAlC nanostructured hard coatings

“…Coatings prepared at low bias voltages are characterized by coarse grains with high density of defect structure and contain dislocations over grain boundaries [27]. On increasing the bias voltage, grain structure refinement, along with the high compressive stress induction in the TiAlC coatings, cause subsequent increase in the hardness [27]. Wang et al reported similar results for nc-TiC coatings [26].…”

“…The trend observed in H and E* is attributed to grain size refinement and compressive stress induction [26]. Coatings prepared at low bias voltages are characterized by coarse grains with high density of defect structure and contain dislocations over grain boundaries [27]. On increasing the bias voltage, grain structure refinement, along with the high compressive stress induction in the TiAlC coatings, cause subsequent increase in the hardness [27].…”

“…It is observed that as the bias voltage increases, the film becomes denser and smoother. This can be attributed to high nucleation density due to increased rate of ion bombardment on the film, resulting in a fine-grained morphology [27]. Voids and the defects at boundaries are observed for low bias voltage between the columns which is in the characteristic zone 1 of Thornton's model [32,33].…”

Reactive co-sputter deposition and properties of CrAlSiN hard films for enhancement of cutting tools

“…This is in agreement with the results of Wang et al [17], for the trend observed in hardness and Young's modulus that was attributed to grain size refinement and compressive stress induction. Increases in the substrate RF bias, grain structure refinement, along with the high compressive stress induction in the CrAlSiN films, lead to increased hardness [18]. Fig.…”

Performance evaluation of reactive direct current unbalanced magnetron sputter deposited nanostructured TiN coated high-speed steel drill bits

“…These coatings have also shown their ability to improve the corrosion resistance of a variety of steel substrates (William Grips et al 2006). Addition of Al into TiN (or CrN) has been shown to improve the oxidation resistance of transition metal nitrides considerably (Barshilia and Rajam 2004a;Barshilia et al 2005. The structure and properties of TiN have been studied in detail by several researchers.…”