Coatings of AlN, TiN and nanostructured multilayer AlN/TiN have been deposited by reactive sputtering on sapphire, tungsten carbide (WC) and stainless steel substrates. The microhardness, adhesion and formation of cracks under indentation tests, were investigated. It was found that the adhesion of coatings on steel was higher, than on WC for all investigated samples. Nanostructured multilayer AlN/TiN films have the best adhesion and fracture toughness both on the hard (WC) and on the soft (stainless steel) substrates if compared with that for AlN and TiN "single layer" coatings. The effect of γ-radiation on mechanical properties of transparent AlN films was investigated. After the exposure of γ-radiation (10<sup>6</sup> Gy) the microhardness of AlN has increased by 33%. No debonding or destruction of AlN films under irradiation was observed.
Multilayer coatings of (Ti, Al) N<SUB>x</SUB>, (Ti, C)N<SUB>x</SUB> and (Nb, C)N<SUB>x</SUB> with bilayer thickness of 0.8 - 8 nm have been deposited by reactive sputtering on stainless steel substrates. Vickers microhardness measurements in the load range of 3.10<SUP>-3</SUP> to 1 N were performed using a self- adjusting tester. It has been shown that in order to obtain the true hardness of multilayer coatings on a softer substrate, the indentation depth should not exceed about 10% of the coating thickness. Indentation criteria for polycrystalline, amorphous and nanostructured multilayer coatings are compared. The obtained criterion for multilayer coatings is close to that for amorphous films.
Solid state bonding of metal with oxide at room temperature have been studied. The properties of Al/SiO<SUB>2</SUB>, Al/glass, Al/MgO, Mg/SiO<SUB>2</SUB>, In/glass interfaces as well as to ascertain the mechanism of formation of interfaces. Structure, composition and mechanical properties were investigated using auger-spectroscopy (AES), secondary-ion mass-spectrometry (SIMS), electron microscopy and precision microindentation. The results showed marked adhesion not all over contact area but only at zones of the maximum shear stress. The effect of mechanoactivation is considered from the viewpoints of both structure formation and physico- chemical interaction of nonequilibrium systems. As a result of relaxation, formation of a narrow metal/O reaction zone spreading in the metal and being characterized by oxygen concentration gradient occurred. The reaction zone exhibits high hardness and brittleness in comparison with those of pure metals.