An extended structure zone diagram is proposed that includes energetic deposition, characterized by a large flux of ions typical for deposition by filtered cathodic arcs and high power impulse magnetron sputtering. The axes are comprised of a generalized homologous temperature, the normalized kinetic energy flux, and the net film thickness, which can be negative due to ion etching. It is stressed that the number of primary physical parameters affecting growth by far exceeds the number of available axes in such a diagram and therefore it can only provide an approximate and simplified illustration of the growth condition?structure relationships.

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A structure zone diagram including plasma based deposition and ion etching - eScholarship

http://liu.diva-portal.org/smash/get/diva2:504302/FULLTEXT01

Strain evolution during spinodal decomposition of TiAlN thin films

Phase stability and oxidation resistance are main objectives when synthesising hard and protective coatings for applications requiring also high thermal stability. Even though TiAlN is a well-studied and nowadays widely used high performance coating, the demand for further optimisation is omnipresent. Recent investigations on quaternary compounds demonstrate that the alloying of Ta to TiAlN films not only results in enhanced phase stability, but also in a significantly increased oxidation resistance. In this study we address thermal investigations of reactive cathodic arc evaporated coatings and elucidate the diverse performance of monolithically grown TiAlN, TaAlN, TiAlTaN, and a multilayered architecture of TiAlN and TaAlN layers. Subtle variations of the bilayer period between 30 and 38 nm were realised by varying the arc current at the TaAl cathode. Our research demonstrates that the quaternary Ti 0.45 Al 0.36 Ta 0.19 N and the multilayered TiAlN/TaAlN coatings feature enhanced mechanical properties and thermal stability as compared with their monolithically grown constituents Ti 0.54 Al 0.46 N and Ta 0.89 Al 0.11 N. All coatings synthesised exhibit as-deposited hardness values of 32 ± 1 GPa, but only the quaternary Ti 0.45 Al 0.36 Ta 0.19 N and the multilayered TiAlN/TaAlN coatings demonstrate pronounced age-hardening with peak hardness values of 37 ± 2 and 35 ± 2 GPa for annealing temperatures of ~ 1000 and 1100 °C, respectively. Complementary X-ray diffraction and differential scanning calorimetry confirm their enhanced phase stability. Even though, also the multilayered design shifts the formation of wurtzite-structured AlN to higher temperatures, only quaternary Ti 0.45 Al 0.36 Ta 0.19 N could withstand ambient air oxidation at 850 °C for 20 h. This is based on the ability of forming a nearly single-phased dense protective mixed oxide scale, having an outermost Al-rich composition. Approximately 70% of this quaternary nitride remained unaffected from oxidation. With the present study we conclusively demonstrate that thermomechanical properties of cathodic arc deposited TiAlN coatings can significantly be enhanced by either forming a quaternary compound or sophisticated architectural design with tantalum, both allow for wide-ranged industrial applications.

Thermal stability and oxidation resistance of arc evaporated TiAlN, TaAlN, TiAlTaN, and TiAlN/TaAlN coatings

The study involved the investigation of the effect of the thickness of the adhesion layers (0.3 and 0.7 μm) and the wear-resistant layer (2.0, 4.0, 6.0, and 8.0 μm) on the microhardness, adhesion bond strength, and performance properties of the ZrN-(Zr,Al,Si)N coatings. The scratch-test method was applied to study the adhesion bond strength to the substrate and coating failure patterns. The study revealed an effect of the coefficient kwa, determining the effect of the thicknesses of the wear-resistant and adhesion layers of the coating on the value of the critical load LC2. The study investigated the wear patterns and mechanisms for the specified coatings and the tool life of tools with these coatings in turning. An effect of the coefficient kwa which is the adhesion and wear-resistant layer thickness ratio on the tool life and a difference in the wear pattern dynamics for tools with these coatings with wear-resistant layers of equal thickness and adhesion layers of different thicknesses was revealed. The study also determined the chemical and phase composition of the coatings.

Effect of adhesion and the wear-resistant layer thickness ratio on mechanical and performance properties of ZrN - (Zr,Al,Si)N coatings

Influence of carbon contents on the structure and tribocorrosion properties of TiSiCN coatings on Ti6Al4V

This paper presents the physical mechanism behind the phenomenon of self-layering in thin films made by industrial scale cathodic arc deposition systems using compound Ti–Si–C cathodes and rotating substrate fixture. For the as-deposited films, electron microscopy and energy dispersive X-ray spectrometry reveals a trapezoid modulation in Si content in the substrate normal direction, with a period of 4 to 23 nm dependent on cathode configuration. This is caused by preferential resputtering of Si by the energetic deposition flux incident at high incidence angles, when the substrates are facing away from the cathodes. The Ti-rich sub-layers exhibit TiC grains with sizes up to 5 nm, while layers with high Si-content are less crystalline. The nanoindentation hardness of the films increases with decreasing layer thickness.

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Layer formation by resputtering in Ti–Si–C hard coatings during large scale cathodic arc deposition

Ti–Si–C–N thin films were deposited onto WC-Co substrates by industrial scale arc evaporation from Ti3SiC2 compound cathodes in N2 gas. Microstructure and hardness were found to be highly dependent on the wide range of film compositions attained, comprising up to 12 at.% Si and 16 at.% C. Nonreactive deposition yielded films consisting of understoichiometric TiCx, Ti, and silicide phases with high (27 GPa) hardness. At a nitrogen pressure of 0.25–0.5 Pa, below that required for N saturation, superhard, 45–50 GPa, (Ti,Si)(C,N) films with a nanocrystalline feathered structure were formed. Films grown above 2 Pa displayed crystalline phases of more pronounced nitride character, but with C and Si segregated to grain boundaries to form weak grain boundary phases. In abundance of N, the combined presence of Si and C disturbs cubic phase growth severely and compromises the mechanical strength of the films.

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Ti-Si-C-N thin films grown by reactive arc evaporation from Ti3SiC2 cathodes

The microstructural evolution of Ti1-xSix cathode surfaces (x=0, 0.1, 0.2) used in reactive cathodic arc evaporation has been investigated by analytical electron microscopy and x-ray diffractometry ...

/pdf/characterization-of-worn-ti-si-cathodes-used-for-reactive-2fyr6tyee1.pdf

Characterization of worn Ti–Si cathodes used for reactive cathodic arc evaporation

The influence of the Ti–Si cathode grain size on cathodic arc processes and resulting Ti–Si–N coating synthesis has been studied. 63 mm Ti–Si cathodes containing 20–25 at.% Si with four dedicated grain size of ~ 8 μm, ~ 20 μm, ~ 110 μm, and ~ 600 μm were fabricated via spark plasma sintering or hot isostatic pressing. They were evaporated in 2 Pa nitrogen atmosphere in an industrial-scale arc deposition system and the Ti–Si–N coatings were grown at 50 A, 70 A, and 90 A arc currents. The composition and microstructure of the virgin and worn cathode surfaces as well as the resulting coatings were characterized using optical and electron microscopy, X-ray diffraction, elastic recoil detection analysis, X-ray photoelectron spectroscopy, and nanoindentation. The results show that the existence of multiple phases with different work function values directly influences the cathode spot ignition behavior and also the arc movement and appearance. Specifically, there is a preferential erosion of the Ti5Si3-phase grains. By increasing the grain size of the virgin cathode, the preferential erosion is enhanced, such that the cathode surface morphology roughens substantially after 600 Ah arc discharging. The deposition rate of the Ti–Si–N coating is increased with decreasing grain size of the evaporated Ti–Si cathodes. The droplet number density and the droplet shape of the coatings are influenced by the arc movement, which is also shown to depend on the cathode grain size.

Influence of Ti–Si cathode grain size on the cathodic arc process and resulting Ti–Si–N coatings

The microstructure evolution and compositional variation of Ti3SiC2 cathode surfaces during reactive cathodic arc evaporation are presented for different process conditions. The results show that p ...

/pdf/microstructure-evolution-of-ti3sic2-compound-cathodes-during-5arfmdl6vh.pdf

Jianqiang Zhu

Papers

Layer formation by resputtering in Ti–Si–C hard coatings during large scale cathodic arc deposition

Ti-Si-C-N thin films grown by reactive arc evaporation from Ti3SiC2 cathodes

Characterization of worn Ti–Si cathodes used for reactive cathodic arc evaporation

Influence of Ti–Si cathode grain size on the cathodic arc process and resulting Ti–Si–N coatings

Microstructure evolution of Ti3SiC2 compound cathodes during reactive cathodic arc evaporation