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Electron microscopy, x-ray diffraction analysis, and micro-and nanohardness measurements were used to investigate the interrelations between the fine structure and the variations in strength properties of nanostructured and nanocomposite Ti-Si-B-N coatings with high oxygen and carbon contents. It has been shown that under the conditions of low-temperature (Т = 200°C) coating deposition, a two-level grain structure forms with {200} texture and grains 0.1-0.3 μm in size fragmented into subgrains 15-20 nm in size. As the silicon content is increased, textureless coatings with the crystal phase grain size less than 15 nm and high amorphous component or coatings of amorphous-crystalline structure are produced. At coating deposition temperatures of 400-450°C, a nanocomposite structure with a grain size d = 10-15 nm and no texture is observed. For all test compositions and conditions of coating production, a Ti 1-x Si x N crystal phase with the lattice parameter a = (0.416-0.420) ± 0.001 nm has been detected. For optimum coating compositions and synthesis conditions, the hardness is over 40-50 GPa. It has been supposed that superhardness can be attained with multiphase grain-boundary interlayers of thickness more than 1 nm.

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