A.V. Bondarev

Structure and properties of nanocomposite Mo—Si—B—(N) coatings

Coatings in the Mo—Si—B—(N) system are obtained using the magnetron sputtering method. Control of nitrogen and silicon content in the coatings is carried out using various gaseous Ar + N2 mixtures and variation of the number of Si segments in the area of MoSiB target erosion. The structure of coatings is studied using methods of scanning and transmission electron microscopy, X-ray analysis, infrared and optical emission spectroscopy, and Raman spectroscopy. Mechanical and tribological properties of the coatings are determined using methods of nanoindentation, scratch-testing, and tribological testing at temperatures of 25, 500, and 700°C. The oxidation resistance of coatings is studied. It is established that coatings with maximum Si and N content possess the best properties: hardness of 32 GPa, elastic recovery of 66%, low friction coefficient at high temperatures, and heat resistance up to 1200°C.

Structure and properties of tribological coatings in Cu-B system

The effect of B additions on the structure and mechanical and tribological properties of Cu coatings produced by magnetron sputtering from mosaic targets has been investigated. It has been shown that the introduction of B results in structure refinement of the coatings. The hardness, elasticity modulus, elastic recovery, and plasticity index of Cu-B coatings have been determined. It has been established that the introduction of 7–15 at % of boron favors a decrease in the coefficient of friction and reduced wear. It has been shown that high tribological characteristics of coatings in the Cu-B system are connected with the formation of solid H3BO3 lubrication on the coating surface.

Superhard Nanostructured Ceramic–Metal Coatings with a Low Macrostress Level

The macrostressed state of (Ti,Al)N–Cu and (Ti,Al)N–Ni ceramic–metal coatings obtained by the arc-PVD method has been studied using X-ray diffraction and by measuring the radius of curvature of a coating–base composite sample (Stoney’s method). It is established that the presence of a tough metal phase favors significant reduction in the level of macrostresses in these structures as compared to those in (Ti,Al)N ceramic coatings, the absolute values of which decrease from 4.7–4.3 to 0.17–0.32 GPa. At the same time, both Ti–Al–Cu–N and Ti–Al–Ni–N coatings retain high hardness of 43 and 51 GPa, respectively, versus 29 GPa for Ti–Al–N coatings. The obtained results give grounds to suppose that the high hardness of the ceramic–metal coatings studied is determined by their nanocrystalline structure rather than by compressive macrostresses.

Hard wear-resistant TiAlSiCN/MoSeC coatings with a low friction coefficient at room and elevated temperatures

TiAlSiCN and TiAlSiCN/MoSeC coatings are fabricated by magnetron sputtering of segmented SHS and compacted powder targets. The structure and composition of coatings are investigated by X-ray phase analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and glow-discharge optical emission spectroscopy. The TiAlSiCN coating is based on the fcc phase with crystallite size <15 nm; the crystallite size decreases under sputtering of TiAlSiCN and MoSeC segments in a ratio of 3: 1 and crystallites amorphized at a ratio of 2: 2. The MoSe2 phase is also found in TiAlSiCN/MoSeC coatings. According to the results of nanoindentation, the hardness of TiAlSiCN coatings is 40 GPa and that of TiAlSiCN/MoSeC coatings is 28 and 12 GPa at ratios of 3: 1 and 2: 2, respectively. The friction coefficient of TiAlSiCN coatings at room temperature is 0.75, it decreases to 0.05 after the introduction of MoSeC, and wear resistance of coatings increases as well. A low friction coefficient (<0.1) under tribological tests of TiAl-SiCN/MoSeC coatings with continuous heating is invariable up to 300°C.