ABSTRACT
Toughness .........................................................................................384 7.3.3 Classication of Coatings According to Mechanical Properties
and Important Ratios ........................................................................ 386 7.4 Hard Coatings with Low Effective Young’s Modulus E* and High Ratio
H/E* ≥ 0.1 .....................................................................................................387 7.4.1 Control of H/E* Ratio by Deposition Parameters Used in the
Formation of Coating ........................................................................ 389 7.4.2 Control of H/E* Ratio by Addition of Selected Me Element in
Coating .............................................................................................. 391 7.4.3 Control of H/E* Ratio by Energy E Delivered to the Growing
Coating .............................................................................................. 391 7.4.3.1 Effect of Substrate Heating ................................................ 392 7.4.3.2 Effect of Ion Bombardment of Growing Coating .............. 393
7.4.4 Control of H/E* Ratio by Combined Action of Deposition Parameters, Added Elements, and Energy E .................................... 395
7.4.5 Highly Elastic Multielement Compound Coatings with H/E* ≥ 0.1 ..... 399 7.5 Hard Coatings Resistant to Cracking ........................................................... 401
7.5.1 Methods Used for Assessment of Resistance of Coating to Cracking ..... 401 7.5.1.1 Indentation Test and Fracture Toughness ..........................402 7.5.1.2 Bending Test ...................................................................... 414
7.5.2 Design of Hard Flexible Coatings Resistant to Cracking ................. 419 7.6 Flexible Multifunctional Coatings ................................................................ 423
Nanocomposite coatings represent a new generation of materials [1-41] and references therein. They are composed of at least two separated phases with nanocrystalline (nc-) and/or amorphous (a-) structure or their combinations. The nanocomposite materials, due to very small (≤10 nm) grains and a signicant role of boundary regions surrounding individual grains, exhibit enhanced or even completely new unique properties compared with the conventional materials composed of larger (≥100 nm) grains. New properties of the nanocomposite materials are caused by the increase of the ratio of the grain surface S and its volume V, and occur when the ratio S/V > 0.1. The high ratio S/V (>0.1) results in the dominance of the grain boundary regions increasing with decreasing grain size d, reduced action of the grain volume, stopping of the generation of dislocations, and the promotion of new processes such as the grain boundary sliding or the grain boundary enhancement due to an interatomic interaction between the atoms of neighboring grains. It means that dramatic changes in properties and behavior of the nanocomposite materials compared with that of the conventional materials are the result of (1) the strong
7.6.1 Two-Functional Tribological Hard nc-TiC/a-C Nanocomposite Coatings ............................................................................................424
