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To improve the mechanical and tribological performance of Al alloy for pistons, a ~ 17 μm thick Ti-DLC multilayer coating composed of alternating Ti and Ti-DLC layers was designed and prepared on the Al alloy substrate by FCVA technology. The microstructure, mechanical properties, high temperature tribological properties and thermal conductivity of the coating were evaluated. The results showed that the added Ti atoms were embedded in the amorphous carbon structure in the form of TiC crystals to form a nanocrystalline amorphous composite structure. The tribological test demonstrated that the multilayer Ti-DLC coating exhibited excellent wear resistance at room temperature, benefiting from the high hardness, high toughness and superior plastic deformation resistance, namely hardness H (~18.1 GPa), Young's modulus E (~168.2 GPa), H/E (~0.11), H3/E2 (~0.21 GPa), and elastic recovery W e (~61.5%) values. At a high temperature test of 300 °C, the coating can maintain outstanding tribological properties with a low friction coefficient of ~0.12 and a low wear rate of ~2.69 × 10−7 mm3/Nm. The thermal conductivity of the multilayer Ti-DLC coating Al alloy substrate was about 30 W/(m∙K) lower than that of the untreated substrate under above 300 °C, which indicated that the multilayer Ti-DLC coating could reduce heat loss and improve fuel, and had the potential to be used as a protective coating for Al alloy pistons. [Display omitted] • Multilayer Ti/Ti-DLC coating was successfully prepared on Al alloy substrate by FCVA. • Microstructure, high temperature tribological performance and thermal conductivity of the coating were investigated. • Coating exhibited excellent wear resistance with low friction coefficient and low wear rate at 300 °C. • Coating showed low thermal conductivity and had the potential to be applied to Al alloy pistons. [ABSTRACT FROM AUTHOR]

• Ti 3 AlC 2 coatings were quickly prepared by FCVA and annealed at 800 °C for 1 h. • Ti 3 AlC 2 phase was formed in the coating at high C 2 H 2 flow rates (≥ 12 sccm). • Hardness and elastic modulus of coatings increased as the C 2 H 2 flow rate increased. • Ti 3 AlC 2 coatings showed high hardness and excellent corrosion resistance. Ti 3 AlC 2 MAX phases have attracted increasing attention due to their unique properties. However, high synthesis temperatures of Ti 3 AlC 2 bulk materials limit their further development. In this work, Ti 3 AlC 2 coatings were prepared by a two-step method with filtered cathode vacuum arc (FCVA) deposition at room temperature and annealing at 800 °C for 1 h. The structure and properties of coatings were investigated. The results showed that the formation of Ti 3 AlC 2 phase in the annealed coating depended on the C 2 H 2 flow rate during deposition. At low C 2 H 2 flow rates (≤ 9 sccm), almost no Ti 3 AlC 2 phase was formed. As the C 2 H 2 flow rate increased, the annealed coatings mainly exhibited Ti 3 AlC 2 phases, the texture of which transformed from (104) to (105) planes. Meantime, the hardness of Ti 3 AlC 2 coatings continuously increased to a maximum of 20.7 GPa, and the corrosion resistance first increased and then decreased with the increase of C 2 H 2 flow rate. [ABSTRACT FROM AUTHOR]

In order to improve the surface properties of Al alloy, TiAlN ceramic coatings composed of alternating TiAl layer and TiAlN layer were prepared by FCVA technology. The influence of N 2 flow rate on the microstructure, mechanical and tribological performance of multilayer TiAlN coatings was systematically studied. The results showed that the coating exhibited a multi-phase structure with mainly fcc TiAlN phase and a small amount of TiN and AlN phases. As the N 2 flow rate increased from 50 to 80 sccm, the preferred orientation varied from TiAlN (220) plane to (111) plane due to lattice distortion. The hardness and elastic modulus of multilayer TiAlN coatings first increased and then decreased with the increase of N 2 flow rate. However, the average friction coefficient and wear rate of multilayer TiAlN coatings exhibited an opposite trend to the hardness, H/E and H3/E2 values. The adhesion gradually decreased from 27.3 to 14.9 N due to the continuous increase of the compressive stress in the coating with the increase of N 2 flow rate. When the N 2 flow rate was 70 sccm, the coating showed the lowest average friction coefficient and wear rate, which was attributed to the highest hardness and the best resistance to cracking and plastic deformation. [ABSTRACT FROM AUTHOR]

TiSiN coatings have attracted extensive attention due to excellent performance in cutting tools, Marine engineering equipment and ship critical components. However, due to the many microparticles and micropores on the coating surface prepared by traditional PVD techniques, the performance of the coatings, especially corrosion resistance, is seriously affected. Therefore, the preparation of high quality TiSiN coatings is very important for the industrial applications. In this study, high-quality TiSiN coatings were prepared by FCVA technique. The effect of N 2 flow rate on microstructure, mechanical properties and corrosion resistance of TiSiN coating was investigated. The results showed that all TiSiN coatings presented smooth and compact microstructure without cracks. Meanwhile, TiSiN coatings had a nanocomposite structure of amorphous Si 3 N 4 encapsulated TiN crystallites and possessed a preferred orientation of TiN (200) plane. With the increase of N 2 flow rate, the grain size and hardness increased first and then decreased. When N 2 flow rate is 20 sccm, the hardness of TiSiN coating reached the maximum owing to the fine grain strengthening effect. Moreover, TiSiN coating deposited N 2 flow rate of 40 sccm had the best corrosion resistance, with the highest charge transfer resistance and pore resistance, which was primarily related to the best surface quality. • High quality TiSiN coating with smooth and compact microstructure were prepared by FCVA technique. • The effect of N 2 flow rate on the structure and properties of TiSiN coating were studied. • The excellent corrosion resistance was due to the good surface quality of TiSiN coating prepared by FCVA technique. [ABSTRACT FROM AUTHOR]