Research on Multilayer Coating of Chinese Tool Coating Materials
Multi-layer coating research of Chinese tool coating materials With the development of coating technology, single-layer multi-component coatings are gradually replaced by multi-layer composite coatings. Depending on the properties of the different coating materials and the cutting conditions, different coating combinations are applied to give the superior performance of the various coatings. More research and better application are double-layer coatings and multilayer composite coatings with layers between 3 and 7.
The TiC/TiN double layer coating combines the high hardness and high wear resistance of the TiC coating, and has good chemical stability and high resistance to crater wear of the TiN coating. Since TiC has a thermal expansion coefficient closer to the substrate than TiN, the residual stress of the coating is small, it is firmly bonded to the substrate, and has high crack propagation resistance, so it is often used as the bottom layer of the multilayer coating. The Al2O3 coating has many excellent properties, but the bonding strength of Al2O3 to the substrate is poor. Depositing a layer of TiC or TiN (such as TiC/Al2O3, TiN/Al2O3) on the substrate can improve the bonding strength of the Al2O3 coating. Other two-layer coatings include TiN/CBN, Al2O3/CBN, TiC/TiBN, and Al2O3/Ti2O3.
There are many combinations of three-layer coatings, such as TiC/TiCN/TiN, TiC/TiCN/Al2O3, TiC/TiN/Al2O3, TiC/Al2O3/TiN, TaC/TiC/TiN, TiN/TiC/TiN, and TiCN/TiC/ TCN, etc., are all based on the advantages of each single coating combined according to different cutting conditions. The most common is the TiC/TiCN/TiN coating, which is the same as the TiC/TiN coating and has better cutting performance than the single TiC and TiN coatings. Most tool coating manufacturers have coating grades of this combination, such as CA9443, CA9721 from Carmet, and KC210 and KC250 from Kennametal.
The addition of an Al 2 O 3 layer to the TiC/TiCN/TiN coating combination results in a more modern coating. For example, Sweden's Sandvik Coromant's new GC2015 grade tool on CIMT2005 is a composite coating with TiCN-TiN/Al2O3-TiN structure, in which the underlying TiCN has high bonding strength with the matrix and good wear resistance. The multilayer structure of TiN/Al2O3 is both wear-resistant and inhibits the crack propagation. The surface TiN has good chemical stability and is easy to observe the wear of the tool. Japan's Fujitsu has developed a new coating called SG, which has a structure of TiN/TiCN/Ti. The coating has a high bonding strength with the substrate, and the surface layer is a Ti-based extraordinary film layer with excellent heat resistance. Sweden's Seco Tool Company uses the new MT-CVD TP3000 blade coating inner layer of TiCN to have strong bonding strength and strength, and the middle Al2O3 as an effective thermal barrier can support higher cutting speed. The outer TiCN guarantees resistance to the rake face and flank wear, and the outermost layer of golden yellow TiN makes it easy to distinguish the wear state of the insert.
Other multi-layer coating combinations are TiC/TiCN/TiN/Al(O,N)/TiN coatings from Widia, Germany, TiC/extraordinary ceramic/Al2O3 coatings from U.S. Mitsubishi Metals, U66; /Wesson's TaC/TiC/Al2O3/TiN combination coating of 680 blades, TiC/TiCN/TiN/ceramic composite coating of StamasterSr17 blade by Tizit Metal Processing Company of Austria.
(Editor: Global Hardware Network)
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