The hottest PVD coating can prolong the service li

2022-08-21
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PVD coating can prolong the service life of tools

Abstract: physical vapor deposition (PVD) technology is often used on cutting tools to prolong the service life of tools and improve their hardness. Of course, different applications have their own specific coatings, which can achieve the best application effect. In general, AlTiN (aluminum titanium nitride) is a common tool coating. For some special processing materials, Al2O3 coating can achieve better results

1 introduction

in the machining process, the cutting tool will bear several aspects of damage, such as cutting heat, high pressure, wear and thermal oscillation. The temperature of the cutting edge will exceed 1000 C. This extreme heat will destroy the binding force of each component of the tool material and other components, and may also cause harmful chemical reactions between the tool and the processed material. Wear is a process that always occurs in the cutting process: the contact surface between the tool and the processed material will bear a pressure greater than 140bar (2000psi). Thermal oscillation: rapid heating and cooling of cutting tools are very common in the machining process; During the cutting process, the blade is heated, and when the blade leaves the cutting surface, the blade is cooled. Mechanical oscillation often occurs when machining intermittent surfaces. According to the specific operation and the low noise of the machined workpiece, mechanical oscillation sometimes plays the role of turning. Adhesion wear often occurs when the processed material adheres to the surface of the tool (forming chip nodules)

2 AlTiN coating

in order to solve the above adverse factors in the cutting process, many cutting tools have deposited a layer of AlTiN coating by arc deposition technology in PVD equipment. AlTiN coatings are mainly used in dry high-speed machining, and have many advantages, such as high hardness (HV> 30gpa), good wear resistance, good high temperature oxidation resistance (850 C), and low thermal conductivity

3 alumina Al2O3 coating

special coating is required in some applications, such as alumina coating. For example, the alumina coating on the cemented carbide blade has the advantages of anti crescent depression and anti thermal cracking. Alumina coated blades are usually deposited by CVD (chemical vapor deposition), but there are some disadvantages: because they are deposited at high temperature (1000 C), the embrittlement of cemented carbide will affect the application of blades in metal cutting, especially in milling. PVD coating of alumina brings many advantages because of its low deposition temperature range (generally between 350 C and 600 C). In particular, high temperature stability, chemical stability and low thermal conductivity are the characteristics of its superior to other coatings. In the milling of stainless steel or the cutting of difficult cutting materials, the aluminum oxide coating of PVD shows better performance than the traditional PVD coating unless forced by the government

by analyzing the interface microstructure of AlTiN coating and alumina coating, alumina coating is well combined with face centered cubic lattice AlTiN. The structure analysis shows that the alumina coating is Amorphous Chromium structure in phase. The grain size is about 5 ~ 10nm. The initial cutting test was to use standard SP12 blades for dry milling crmo4 steel

4 hybrid coating equipment

PVD coating equipment using hybrid coating technology: cathode arc evaporation technology and magnetron sputtering technology are mixed in one process. The hybrid technology combines the advantages of PVD hard film, excellent wear resistance, low friction coefficient and low chemical activity. As a bonding layer, arc coating provides necessary wear resistance to the whole coating; Alumina coating has temperature and chemical stability

before deposition, the processed workpiece is heated to the process temperature, and the system is pumped to the base pressure. The workpiece is then etched by argon ions or metal ions. Then the arc layer is deposited, and the aluminum oxide coating on its top is obtained by sputtering under the conditions of metal target and argon oxygen mixture gas. In addition, alumina coating can also be used as a separate coating in some special cases. The alumina coating is deposited by a specially designed sputtering cathode combined with an optimized design system of process gas. The closed-circuit magnetic field formed by the electromagnetic induction coil forms a plasma with high ionization rate near the workpiece, so as to achieve the required coating performance. The advantage of this technology is that the process is easy to control, and the stability of the deposition process is conducive to achieving the best indoor air quality. The deposition rate (0.5 m/h) can fully meet the needs of industrial production

5 conclusion

tool coatings deposited by arc technology, such as AlTiN coating, can further improve the application performance of tools. The next development of tool coating technology should be a hybrid technology based on arc technology and sputtering technology. It is the combination of these two technologies that forms the basis for a new breakthrough in tool application performance. However, most primary plastic products used in packaging are not recycled

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