Research on Multi-component Coatings of Chinese Tool Coating Materials

Due to the hardness of the substrate and the coating, the single-coated tool has a far difference in elastic modulus and thermal expansion coefficient, and the lattice type is also different, resulting in an increase in residual stress and a weak bonding force. Adding new elements to a single coating (such as adding CrY to improve oxidation resistance, adding Zr, V, BHf to improve wear resistance, adding Si to improve hardness and chemical diffusion) to prepare a multi-tool coating material, greatly improving the overall performance of the tool.

The most common multi-tool coatings are TiCN and TiAlN coatings. The TiCN coating combines the good toughness of the TiCTiN coating. The coating process can control the TiCN properties by continuously changing the CN composition, and can form different composition gradient structures, reduce the internal stress of the coating, improve the toughness, increase the coating thickness, and prevent Crack propagation reduces chipping.

TiCN coating technology continues to evolve. In the 1990s, new technologies for temperature chemical vapor deposition (MT-CVD) emerged, revolutionizing CVD technology. The MT-CVD technique uses organic acetonitrile (CH3CN) as the main reaction gas, and a TiCN coating is formed below 700 °C. This TiCN coating method effectively controls the formation of very brittle η phase (Co3W3C) and improves the wear resistance, thermal shock resistance and toughness of the coating. Studies have shown that the appropriate increase of ion beam bombardment in PVD deposition of TiCN coating can also significantly improve the hardness and wear resistance of the coating. In recent years, new coating materials based on TiCN (such as TiZrCN, TiAlCN, TiSiCN, etc.) have also appeared.

TiAlN coating material is currently used in one of the most widely used high-speed carbide tool coatings. TiAlN has high temperature hardness and excellent oxidation resistance. The coating composition is converted from Ti0.75Al0.25N to Ti0.5Al0.5N. The oxidation temperature of Ti0.5Al0.5N coating is 800 °C, and a layer of amorphous Al2O3 film is formed on the high-speed processing surface to protect the coating. At present, people will focus on improving the TiAlN coating to meet the increasing demand for applications such as oxidation resistance, thermal stability and thermal hardness. At present, CemeCon of Germany adopts high ionization sputtering technology (HIS®) to obtain advanced TiAlN coating. The coating has excellent adhesion to the substrate, avoiding the deposition of molten material in the form of droplets when using multi-arc ion plating technology. Surface phenomena, resulting in a very smooth and smooth surface coating. Balzers' newly developed X.CEED coating is also a single layer of TiAlN coating with excellent red hard oxidation resistance, and the coating has good bonding strength with the substrate even under severe conditions. Mitsubishi's MIRACLE coating contains Al-rich (Al,Ti)N coatings, which directly process hardened steel by greatly increasing the film's hardness and oxidation resistance.

The TiBN coating is based on TiNTiB2 to develop a multi-layer coating, which not only enhances the hardness of the TiN coating, but also maintains good toughness, avoids the brittleness of the BN coating TiB2 coating, and significantly improves the wear resistance and corrosion resistance of the coating tool. The friction coefficient is low. The bonding strength of the Ti-BN coating deposited by CHeau et al. on the sputtered Ti-B target was improved and the microhardness of 44 GPa was achieved. CemeCon develops a TiAlBN coating. Through the change of boron content, the process produces a so-called "real-time" phenomenon, that is, BN and B2N3 are formed by boron diffusion, thereby obtaining a lubricating film layer which is favorable for cutting. In addition, Hitachi has developed a TiBON coating with a low coefficient of friction at high temperatures.

TiN is added to the Si element to form a TiSiN multi-component coating, and its high temperature oxidation resistance is significantly improved compared to the single coating TiN. Hitachi, Japan developed a hard-cutting TiSiN coating with a 36GPa hardness of 1100 °C to start the oxidation temperature. In addition, Hitachi also replaced the Ti element with Cr to develop lubricity, which is more suitable for the processing of adhesive materials such as aluminum and stainless steel. The CrSiN coating and the quaternary have a super oxidation resistant AlCrSiN coating.

Another representative multi-component coating from Balzers replaces the Ti-alloy AlCrN coating with Cr, called G6. The coating has a microhardness of HV3200 and can be used at temperatures up to 1000 ° C. It has a toughness that exceeds that of titanium-based coatings (such as TiAlN). , TiCN), more suitable for interrupted cutting difficult material processing.

Chengdu Tool Research Institute has developed two series of high-performance multi-component composite coatings in China's first series of Ti-CNO-AlTi-CNB. It has excellent composite mechanical properties and excellent cutting performance. It is mainly used in automotive tools and Hertel series of comb combs. Other multi-coat materials include TiMoN, TiCrN, NbCrN, NbZrN and the like.


(Editor: Global Hardware Network)

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