Structure–performance relations in nanocomposite coatings

Solid particle erosion mechanisms of protective coatings for aerospace applications

“…However, as illustrated in Figure 2.7, under a critical grain size an inverse Hall-Petch effect can be observed because of grain boundary slipping [46]. One of the most studied nanocomposite systems is composed of nano-crystalline TiN in an amorphous SiN matrix [42,[47][48][49][50]. For such as system, Veprek et al [49] demonstrated that maximum hardness is achieved at the percolation limit of the amorphous phase in the threedimensional network of nanocrystalline grains (typically between 5 and 10 nm in size).…”

Near-edge X-ray absorption fine structure studies of Cr1−xMxN coatings

“…Transition metal nitrides (i.e., CrN, TiN etc) have been found to show superhardness (hardness > 40 GPa) with suitable doping (i.e., Si, Al etc.) [14][15][16]38]. The Si or Al dopant significantly modifies the microstructures of the binary compounds from closely-packed columnar grains into nanocrystalline structures embedded in an amorphous matrix [14][15].…”

“…large band-gap [2][3][9][10][11], high surface acoustic velocity [2], corrosion resistance [2], oxidation resistance [12], excellent chemical and thermal stability as well as mechanical robustness [13]. Recently, superhardness (hardness, or H > 40 GPa) has been obtained in TiN, and CrN by Si doping [14][15][16]. It is believed that the addition of Si changes the microstructures of the binary compounds from closely-packed columnar grains into nanocrystalline structures integrated in a Si 3 N 4 amorphous matrix [14][15].…”

“…Recently, superhardness (hardness, or H > 40 GPa) has been obtained in TiN, and CrN by Si doping [14][15][16]. It is believed that the addition of Si changes the microstructures of the binary compounds from closely-packed columnar grains into nanocrystalline structures integrated in a Si 3 N 4 amorphous matrix [14][15]. Superhardness [17] has also been reported in CrN with a suitable amount of Aldoping.…”

Factors governing the mechanical behaviour of CrSiN coatings: Combined nanoindentation testing and transmission electron microscopy

“…Chromium nitrides (CrN) have attracted considerable attention owing to their good combination of mechanical and thermal properties [1,2] compared to other nitrides of transition metals, such as TiN [3]. More recently, superhardness (hardness > 40GPa) has been achieved in titanium nitrides by the addition of Si that changes the microstructure from closely packed columnar TiN grains into TiN nanocrystals embedded in a Si 3 N 4 amorphous matrix [4,5]. Such extremely high hardness is attributed to the combined effects of the fine grain size together with the strong interfacial bonding between the TiN nanocrystals and the surrounding amorphous phase.…”