## 2 Experimental Procedure  
TiCrN films were deposited by CAPVD technique using two separate targets, which can produce independent plasma flows. The rotatable substrate holder was placed in the center of the chamber. Hence, for thin coatings of TiCrN, samples of tungsten carbide (WC) (30 \(\times\) 30 \(\times\) 5 mm\({}^{3}\)) were taken. A flat surface of the substrate was polished up to 1 \(\upmu\)m diamond paste to obtain the required surface finish. Prior to coating, substrates were cleaned and conditioned thoroughly through a series of processes. The specimens were ultrasonically cleaned by ethyl alcohol then chemically cleaned for 40 min in the Thermovide V300 Pre-cleaning Unit, maintained at a temperature of 60-70 \({}^{\circ}\)C. The plasma was generated from the cathode spot on pure Ti and Cr targets (chamber wall used as anode). The two plasma sources operated simultaneously during the TiCrN film deposition process. The distance between the sample and the rotating cathode was 6.5 cm. Prior to deposition, the chamber was evacuated to a base pressure of 10\({}^{-6}\) mbar. The chamber was heated up to 450 \({}^{\circ}\)C with a continuous flow of argon of a range of 15-27 sccm. During the deposition of films, nitrogen and argon gases were introduced into the deposition chamber with N2 partial pressure of 2 \(\times\) 10\({}^{-5}\) mbar. The flow rate of nitrogen gas was 300 sccm. The temperature of the substrate during coating was set at 400 \({}^{\circ}\)C. Six sets of experiments were performed by keeping the substrate bias at \(-\)50 V. The arc currents for Ti were kept at 175 A and for Cr it varied from 80 A to 175 A. T1, T2, T3, T4, and T5 samples are for the Cr current 80, 100, 125, 150, and 175 A, respectively, keeping constant Ti current at 175 A (Table 1). In the case of the T6 sample, the Cr and Ti current were kept at 175 and 100 A, respectively. During the deposition of films, N\({}_{2}\) was introduced into the deposition vacuum chamber with N\({}_{2}\) partial pressure of 2.1 \(\times\) 10\({}^{-5}\) mbar. All the coatings discussed in this section were deposited to a uniform thickness of 3.2 \(\mu\)m.  
The coatings were also comprehensively characterized for their phase composition, residual stress, and hardness using X-ray diffraction (XRD) (X'Pert Pro, Panalytical, Malvern, UK) (20-glancing angle, Cu-\(K\alpha\), 45 kV) and nanoindentation (NHT, CSM) equipped with Berkovich indenter, respectively. The surface morphology and composition of the coatings were studied using scanning electron microscopy (SEM: HITACHI S-3400 N, Hitachi, Tokyo, Japan) with energy dispersive spectroscopy (EDS: HITACHI S-3400 N), respectively. The hardness results presented are an average of 20 indentations (load 50 mN in sinus mode). The details of the test parameters are listed in Table 2. The instrument was operated in sinus mode and the indentations were made using a sinus frequency of 10 Hz. The hardness and elastic modulus were determined using the Oliver analysis [32; 33; 34]. Conventional ball-on-disc equipment was used to measure the coefficient of friction (COF) and to determine the sliding wear rate (WR) of the coatings. ASTM G-99 is followed for the wear test. The stress analysis was carried out using the \"sin\({}^{2}\)\(\varphi\)\" method. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Coating** & **TiCrN I** & **TiCrN II** & **TiCrN III** & **TiCrN IV** & **TiCrN V** & **TiCrN VI** \\
**Parameters** & **(T1)** & **(T2)** & **(T3)** & **(T4)** & **(T5)** & **(T6)** \\ \hline Ti Current (A) & 175 & 175 & 175 & 175 & 175 & 100 \\ Cr Current (A) & 80 & 100 & 125 & 150 & 175 & 175 \\ Cathode Speed (rpm) & 11 & 11 & 11 & 11 & 11 & 11 \\ Vacuum Pressure (mbar) & \(10^{-6}\) & \(10^{-6}\) & \(10^{-6}\) & \(10^{-6}\) & \(10^{-6}\) & \(10^{-6}\) \\ Heat Treatment (\({}^{\circ}\)C) & 450 & 450 & 450 & 450 & 450 & 450 \\ Bias & 50 & 50 & 50 & 50 & 50 & 50 \\ Voltage (V) & & & & & & \\ \end{tabular}
\end{table} 
Table 1: Coating parameters for TiCrN thin film deposition.