The influence of Ti plasma etching pre‐treatment on mechanical properties of DLC film on cemented carbide

Abstract

The pre-treatment of substrate surface had been a key part of DLC film preparation to improve mechanical and tribological properties. Ti plasma etching pre-treatment was investigated in this paper as a new effective surface pre-treatment method to substitute transition layer. This pre-treatment used high-energy Ti plasma to impact substrate surface. Ti plasma etched the substrate to a depth of 407 nm and increased the roughness from 1.36 to 40.39 nm. A trace layer of substrate, together with cobalt, oxides, and other impurities, was removed. Ti plasma broke some top WC crystals and combined with the free carbon ions separating from the substrate. A DLC film was deposited on the etched surface. Compared with DLC films deposited on the untreated substrate and Ti transition layer, the DLC film on the Ti plasma etched substrate had best adhesion strength of 34.14 N. The three DLC films had the same sp 3 bonding carbon content, but Ti plasma etching treatment could promote the formation of sp 3 bonds on the interface of substrate and DLC film. This DLC film had low friction coefficient of 0.12 and low wear rate of 5.11 Â 10 À7 mm 3 / mÁN. In summary, Ti plasma etching pre-treatment could significantly improve the adhesion of DLC film and keep its excellent tribological properties.

Structure and mechanical properties of diamond‐like carbon films prepared by pulsed laser‐induced cathodic vacuum arc technique

“…The Ti interlayer exhibits a dense and compact columnar structure from a partially enlarged zone on the bottom left corner of Figure 6C. increases to 0.019 μm at 330 V. It is found that the higher the sp 3 content is, the smaller the surface roughness is. The deposition process is the dynamic balance of surface growth and surface damage.…”

“…The physical structure and sp 3 /sp 2 ratio of DLC films were characterized using a Renishaw Raman imaging microscope equipped with a 514 nm line of an Argon ion (Ar + ) laser. The laser power on the sample was approximately 2 mW and accumulated for 20 s. X-ray photoelectron spectroscopy (XPS, PHI5000 Versa) was used to analyze the C1s core level spectra and sp 3 working in contact mode. The collection area and pixels of the images were 2 Â 2 μm and 256 Â 256 points.…”

“…[29][30][31] The relative concentration (at%) of all the DLC films is summarized in Table 1. It is found that the sp 3 ions is adverse to the formation of the sp 3 bond. 15 The DLC deposited at 280 V is observed to have the highest sp 3 content; while further increasing arc voltage, the sp 3 content is decreased.…”

“…Diamond-like carbon (DLC) films, transition metal nitride and carbide films that are prepared on cutting tools and drillings have been applied to improve their properties. [1][2][3][4][5] However, the DLC films, especially, tetrahedral amorphous carbon (ta-C) films, have attracted considerable interest in properties comparable with those of nitride and carbide films, such as high hardness, low friction coefficient, excellent wear resistance, and anti-affinity with wear debris. [6][7][8][9] Among the many preparation methods for DLC films, the filtered cathodic vacuum arc (FCVA) technique is an effective and common method.…”

“…[13][14][15][16] The ion energy has a proportional relation to the fraction of sp 3 ; the optimal range is between 50 to 240 eV. 17 The substrate temperature would affect the transformation from sp 3 to sp 2 ; it is observed that the DLC films began to become more sp 2 fraction as a threshold deposition temperature value of 150-200 C. 16,18 It is suggested that the processing parameters should be controlled in a suitable range to improve the expected properties. The properties of the DLC films prepared by the PLICVA technique are outstanding and have attracted much attention.…”