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In this work, the competitive relationship between the double amorphous phases is systematically investigated to increase the high-temperature wear resistance of the self-lubricating TiAlSiCN coating. These double amorphous phases combine the SiN x phase with high-temperature resistance and the C-related phase with a low friction coefficient. An increase in the Si content facilitates the change in the phase composition. The resultant coating exhibits an adhesion strength of 153 N, a friction coefficient of 0.24 and a hardness of 25.24 GPa upon generation of the TiAlN(C), the SiN x and the C-related phase. In this case, the TiAlSiCN coating achieves long-term self-lubrication at high temperatures with the titanium alloy friction pair. This mechanism stems from the SiN x phase replacing the portion of the easily oxidized amorphous C-related phase, which yields an enhanced high-temperature wear resistance. The cutting distance of this TiAlSiCN is 120% higher than that of the TiAlCN during the high-speed cutting of the titanium alloy. This outcome provides an effective solution for high-temperature applications of self-lubricating coatings. • Long-term self-lubricating is remained in TiAlSiCN coating by optimal Si content. • Synergistic effect of amorphous SiN x and C-related phase is solved in TiAlSiCN. • Tool life of TiAlSiCN improved 225% by comparing with that of TiAlN. [ABSTRACT FROM AUTHOR]

Tool coatings with a high coefficient of friction (COF) form a built-up edge between the tool and the piece of work when cutting titanium alloy, creating a high cutting temperature, decreased tool life, and lowing the cutting quality. TiAlN/WS self-lubricating composite coatings with high adhesion were prepared via the multilayer growth of WS with low COF and TiAlN with high wear resistance. The TiAlN/WS coating had high adhesion (135.4 N), low COF (0.261), and unchanged hardness (14 GPa). The low COF and high wear resistance originated from the self-lubricating wear-resistance debris at the micron scale with TiAlN coated with amorphous WS. The coating reduced the adhesive wear. By comparing the machining results of the TiAlN/WS coating with those of the TiAlN coating, the flank wear was 45.9% lower for the same cutting length, the machining speed increased from 41 m/min to 100 m/min, the cutting length was over 200% higher at the same flank wear of 0.3, and the self-lubricating composite coating showed good results under dry cutting conditions. Therefore, this coating provides a method for use in high-speed and environmentally-friendly machines for difficult-to-cut materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The TiAlCN coating with high adhesion (156 N) and low friction coefficient (0.231) was deposited. • The TiAlCN coating can form a special structure of nano-crystalline wrapped by C-related amorphous phase by adjusting the C/N ratio. • The TiAlCN coating reduces wear and inhibits the adhesive wear during high-speed cutting titanium alloy. The cutting temperature will be significantly increased while cutting high reactive titanium alloy due to the large friction coefficient of the traditional TiAlN coated tools. The tool could also easily appear adhesive wear and thereby reduce the service life. In this work, TiAlCN coatings with high adhesion and low friction coefficient were deposited by changing the C 2 H 2 and N 2 flow rates and using medium-frequency magnetron sputtering. Compared with the TiAlN coating, the hardness of the TiAlCN coating increases up to the value of 20.36 GPa, the toughness is improved by about 230%, the adhesion reaches the value of 156 N. However, the friction coefficient is only 0.231. This performance improvement is attributed to the special structure of (Ti,Al)(C,N) nano-crystalline wrapped by a C-related amorphous phase that is formed in the coating. The structure can be formed by adjusting the C/N ratio to make the C atom content exceed the solid solubility but the C/N ratio does not reach saturation. This kind of TiAlCN coating reduces the wear and inhibits the adhesive wear during the high-speed cutting process of titanium alloy. The cutting distance is also increased by 50% compared with the TiAlN coating. [ABSTRACT FROM AUTHOR]

In order to satisfy the requirements of tool coatings for high speed cutting of titanium alloy, it is necessary to add Si element into TiAlN-based tool coating to enhance the hardness of the coating, but it will reduce the adhesion and the cutting performance. In this paper, the gradient TiAlSiN coating is deposited with out-of-plane Si gradient distribution by magnetron sputtering. By this way, the hardness of the coating can maintain that of the non-gradient TiAlSiN coating by more than 70%, which is 147% higher than that of the TiAlN coating. Meanwhile, the adhesion increases by 300% compared to the adhesion of the non-gradient TiAlSiN coating and reaches to 100 N. The gradient TiAlSiN coating has a 75.4% higher cutting distance than that of the non-gradient TiAlSiN coating when cutting titanium alloy. This study provides a method to further improve the adhesion of titanium alloy cutting tool coatings. • Gradient structure improves adhesion of coating while maintaining hardness. • Adhesion of gradient TiAlSiN coating increases by 300% than that without gradient. • Cutting distance increases by 75.4% due to Si gradient in TiAlSiN coating. [ABSTRACT FROM AUTHOR]