Coated tools
Surface coating is applied to the tool (blade) substrate with good toughness, and a thin layer of materials with high hardness, high wear resistance, and high temperature resistance (such as TN, T; C etc.), so that the cutter (blade) has a comprehensive and good comprehensive performance.
The rapid development of coating technology has led to the widespread use of coated tools. In 1969, Krupp in Germany and Sandvik in Sweden successfully developed CVD coating technology and introduced TC coated carbide insert products by CVD method to the market. In the early 70s of the 20th century, United States R. Runshan and A. Raghuran developed the physical vapor deposition PVD process and introduced the PVD TN high-speed steel cutting tool product to the market in 1981. At that time, the CVD coating process temperature was about 1000°C, and it was mainly used for the surface coating of tungsten carbide tools (blades); The PVD coating process temperature is 500°C and below 500°C, which is mainly used for the surface coating of high-speed steel tools. Later, CVD and PVD coating technology developed rapidly, and great progress was made in coating materials, coating equipment and processes, and the development of multi-layer material coating technology, so that the performance of coated tools (blades) has been greatly improved. In the past, PVD coating technology was mainly used for high-speed steel tools, but in recent years, with the rapid development of PVD coating technology, it can also be successfully used for carbide tools (blades), accounting for half of the carbide-coated tools (blades). At present, coated high-speed steel tools and coated carbide tools (blades) are widely used, accounting for more than 50% of the total use of all tools.
1. Chemical Vapor Deposition (CVD)
In the past, tungsten carbide tool surface coatings were coated using a high-temperature chemical vapor deposition (HTCVD) process. In the deposition system of atmospheric pressure or negative pressure, pure H, CH, N, TiCL, AICL, CO, and other gases are evenly mixed according to the composition of the sediment according to a certain ratio, and then coated on the surface of the cemented carbide blade with a certain temperature (generally 1000~1050 °C), that is, TC, TN, TCN, AL, O, or their composite coatings are deposited on the surface of the blade. Until now, HTCVD is still the most used process method, in addition to HTCVD, there is also plasma chemical vapor deposition (PCVD) process, which is another method of coating on the surface of cemented carbide tools (blades), because the coating process temperature is low (700~800 °C), so the flexural strength of the blade is reduced. Because TC is closest to the linear expansion coefficient of the matrix material, a thin layer of TC is usually applied to the surface of the substrate first, and then TN, AL, 0, such as TC-TiNTiC-AL,O,TC-TiCN. TIN and so on.
Later, various countries developed a variety of different combinations of multi-layer coatings, which include: TiCN-AL, O, TiCN-TC TN, TCN. TC AL,O,,TICN ALO, TIN,TICN. TIC-AL,O, TIN,TICN. AL,O,-TCNTiC-TICN-TIN, TN-TICN-TIN, etc. It can be seen that TCN or TN has been used as the base layer more often in recent years, due to the improvement of the base carbide, such as the gradient structure. In addition, TN coating should not be used alone, because the hardness of TiN does not increase much compared to cemented carbide, and TN must be used in combination with TC, TiCN, AL,O, etc.
2. Physical Vapor Deposition (PVD)
In the early days, PVD coatings were all used "vacuum evaporation method", the film layer was often uneven, and the combination with the substrate was not strong enough, and then the "vacuum magnetron sputtering method" and "vacuum plasma plating process" and other processes were developed, and the effect was very good. At present, the latter two methods are mainly used for tool surface coating.
In the early years, PVD coating was only used for high-speed steel tools, and TN was used as the coating material. Later, the coating process was improved, a variety of coating materials and multi-layer coatings were developed, and a large number of applications were also obtained on tungsten carbide tools. The coating effect is much better than ever. TN coating materials are still in use, and the emerging coating materials are TAIN and AITIN, which are better used than TiN.
Europe has the highest level of PVD coating technology, ahead of other countries and regions. Well-known manufacturers include 0erlkonBalzers, PVT Plasma Vacuum Technology in Germany and Unimerco in Denmark. Their PVD coating equipment and technology are advanced, with a wide variety of coating materials, and good performance of coated knives and other products.
