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The CrAlC coating has broad application prospects as a high temperature protective material due to its unique properties. However, it is difficult to control the properties of CrAlC coating due to the multiphase structure produced by thermally induced solid-reaction. In this paper, the CrAlC coating was prepared by filtered cathodic vacuum arc (FCVA) technology. In order to elucidate the relationship between the phase structure evolution and the properties, the structure, mechanical and electrochemical properties of the CrAlC coating before and after annealing were systematically investigated. The results illustrated that the CrAlC coating changed from amorphous structure to crystalline structure after annealing, and the phase composition varied with the increases of annealing temperature. As the annealing temperature increased from 700 °C to 800 °C, the content of Cr 23 C 6 and Al 4 C 3 increased. However, with further increasing the annealing temperature to 900 °C, the content of Al 4 C 3 gradually decreased, and the Cr 23 C 6 phase was transformed into Cr 7 C 3 and Cr 3 C 2 phases. In addition, the hardness and corrosion resistance of the coating first increased and then decreased with the increase of annealing temperature. When the annealing temperature was 800 °C, the CrAlC coating had the highest hardness (18.28 GPa) and the best corrosion resistance with the smallest corrosion current density (8.54 × 10-9 A/cm2). [Display omitted] • CrAlC coatings annealed at different temperatures were prepared. • A multi-phase structure dominated by Cr 23 C 6 with little Al 4 C 3 and Cr 3 C 2 was formed. • Increasing annealing temperature causes hardness to increase first and then decrease. • Cr 23 C 6 significantly improved the electrochemical corrosion resistance of the CrAlC coating. [ABSTRACT FROM AUTHOR]

The CrAlC coating has broad application prospects as a high temperature protective material due to its unique properties. However, it is difficult to control the properties of CrAlC coating due to the multiphase structure produced by thermally induced solid-reaction. In this paper, the CrAlC coating was prepared by filtered cathodic vacuum arc (FCVA) technology. In order to elucidate the relationship between the phase structure evolution and the properties, the structure, mechanical and electrochemical properties of the CrAlC coating before and after annealing were systematically investigated. The results illustrated that the CrAlC coating changed from amorphous structure to crystalline structure after annealing, and the phase composition varied with the increases of annealing temperature. As the annealing temperature increased from 700 °C to 800 °C, the content of Cr 23 C 6 and Al 4 C 3 increased. However, with further increasing the annealing temperature to 900 °C, the content of Al 4 C 3 gradually decreased, and the Cr 23 C 6 phase was transformed into Cr 7 C 3 and Cr 3 C 2 phases. In addition, the hardness and corrosion resistance of the coating first increased and then decreased with the increase of annealing temperature. When the annealing temperature was 800 °C, the CrAlC coating had the highest hardness (18.28 GPa) and the best corrosion resistance with the smallest corrosion current density (8.54 × 10-9 A/cm2). [Display omitted] • CrAlC coatings annealed at different temperatures were prepared. • A multi-phase structure dominated by Cr 23 C 6 with little Al 4 C 3 and Cr 3 C 2 was formed. • Increasing annealing temperature causes hardness to increase first and then decrease. • Cr 23 C 6 significantly improved the electrochemical corrosion resistance of the CrAlC coating. [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]