Nanostructured TiC/a-C coatings for low friction and wear resistant applications

Abstract

Closed-field unbalanced and balanced magnetron sputtering was used to deposit nanocrystalline TiC (nc-TiC)/amorphous carbon (a-C) nanocomposite coatings with hydrogenated or hydrogen-free a-C matrix, respectively. The contents of Ti and C in the coatings have been varied over the full range of interest (7-45 at.% Ti) by changing the flow rate of acetylene gas or the locations of substrates relative to the center of C/TiC targets. Different levels of bias and deposition pressure were used to control the nanostructure. The nanocomposite coatings exhibit hardness of 5-35 GPa, hardness/E-modulus ratio up to 0.15, wear rate of 4.8Â10 À17 m 3 /N m lap, friction coefficient of 0.04 under dry sliding and strong self-lubrication effects. The nanostructure and elemental distribution in the coatings have been characterized with cross-sectional and planar high-resolution transmission electron microscopy (HRTEM) and energy-filtered TEM. The influence of the volume fraction and size distribution of nc-TiC on the coating properties has been examined. D

Control of crystallinity in sputtered Cr–Ti–C films

“…Typically, the group IV metals Ti, Zr, and Hf form crystalline films although the carbide often is present as nano-sized crystallites in an amorphous carbon (a-C) matrix, depending of the C content. The properties of these nanocomposites are typically affected by the relative amount of a hard carbide phase in a softer a-C matrix [4][5][6][7]. For the 3d transition metals, the tendency to form amorphous films increases with increasing number of d-electrons in the metal and sputtered Cr-C and Fe-C films are therefore often amorphous [8][9][10][11].…”

Advanced characterisation of nanocomposite coatings

“…[1][2][3][4], and the possibility to develop self-adaptive coatings for tribological applications [5].…”

Atomic-scale microstructure underneath nanoindentation in Al-Cr-N ceramic films

“…As well, AFM images are also obtained at the micrometer level, only showing the surface morphologies of indentation impressions. [15][16][17][18][19][20][21][22][23][24][25] Comparing with optical and AFM images, SEM images have a better resolution of indentation impressions. However, little data has focused on the atomic-scale microstructure underneath the indenter, although the cross-section and surface morphologies with columnar or nanocrystalline structures have been broadly reported.…”