February 17, 2022
The coating tool is prepared by coating a thin layer of refractory metal or nonmetal compound with good wear resistance (also can be coated on ultra-hard material blades such as ceramic, diamond and cubic boron nitride) on the surface of tungsten carbide or high speed steel (HSS) substrate with good strength and toughness by vapor deposition method. The coating acts as a chemical and thermal barrier, reducing the diffusion and chemical reaction between the tool and the workpiece, thereby reducing the wear of the matrix. Coating tool has high surface hardness, good wear resistance, stable chemical properties, heat resistance and oxidation resistance, small friction coefficient and low thermal conductivity characteristics, cutting than uncoated tool life increased 3~5 times more than, improve the cutting speed of 20%~70%, improve processing accuracy 0.5~1 level, reduce tool consumption cost 20%~50%.
Coated cutting tools have become the symbol of modern cutting tools, in the tool used in more than 50%. Various cutting tools used in machining, including turning tool, boring tool, drill, reamer, broach, tap, thread comb, rolling head, milling cutter, forming tool, gear hob and gear shaper, etc., can be coated to improve their performance.
The coating material must have high hardness, good wear resistance, stable chemical properties, no chemical reaction with the workpiece material, heat resistance and oxidation resistance, low friction coefficient, and solid adhesion with the matrix and other requirements. Obviously, a single coating material is difficult to meet the above requirements. Therefore, the hard coating materials have been only coated with a single TiC, TiN, Al2O3 at first, into the development of thick film, composite and multiple coatings in a new stage. The newly developed TiCN, TiAlN, TiAlN multilayer, ultra-thin, ultra-multilayer coatings are combined with TiC, TiN, Al2O3 and other coatings, and the new anti-plastic deformation matrix has made great progress in improving the toughness of coatings, the bonding strength between coatings and substrates, and improving the wear resistance of coatings. The technology of coating diamond film on carbide matrix has been broken through and the performance of cutting tool has been improved comprehensively.
TiN is the most mature and widely used hard coating material, but the bonding strength between TiN and the matrix is not as good as TiC coating, the coating is easy to peel off, and the hardness is not as high as TiC, and the film is easy to be oxidized and ablated when the cutting temperature is higher. TiC coating has high hardness and wear resistance, oxidation resistance, but its brittle, impact resistance. TiCN has the advantages of TiC and TiN. It can control TiCN properties by continuously changing the composition of C and N during the coating process, and form a multi-layer structure of different components, which can reduce the internal stress of the coating, improve the toughness, increase the thickness of the coating, prevent the expansion of cracks, and reduce the edge breaking. TiCN based coating is suitable for processing ordinary steel, alloy steel, stainless steel and wear-resistant cast iron, and the material removal rate can be increased by 2~3 times.