Summary

Some technological results for the synthesis of superhard nanocomposites are presented in Table 1. First of all, the coatings achieve microhardness greater than or equal to 40 GPa owing to a resultant optimal nanostructure. The bilayer repeat periods vary usually within a narrow range from 0.5 to 17 nm; the ratio of thickness of the first phase (h1) to the bilayer repeat period (A) amounts to 0.3-0.4 predominantly. The exceptions are the nanolayered composites of TiN/Ti, HfN/Hf, WN/W, and TiN/NbN where hTiN/A reaches approximately 0.5, TiN/TaN where hTiN/A = 0.34 — 0.64, and NbN/TaN where the maximum microhardness is achieved when hNbN = hTaN and the bilayer repeat period is 0.64. The microhardness data vary approximately as the inverse square root of the bilayer repeat period (A) [572]. Their microhardness follows the Hall-Petch strengthening mechanism as applied to nanolayered composites [494].

Some tribological results, which have been achieved, are presented in Table 2. Certain nanolayered composite

Table 1. Summary of the technological characteristics for the synthesis of superhard nanolayered composites.

Composition (type) of nanolayered coating

Maximum microhardness (GPa)

Range of

Coating thickness (Um)

Deposition conditions

Temperature of substrate (°C)

Method

Pressure (Pa)

Composition (type) of nanolayered coating

Maximum microhardness (GPa)

Coating thickness (Um)

Temperature of substrate (°C)

Method

Pressure (Pa)

TiN/VN

0 0

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