How much do you know about PVD process?
Development of vacuum coating technology
I. vacuum coating technology has not been developed for a long time. CVD(chemical vapor deposition) technology was applied to carbide cutting tools in the 1960s.As this technology needs to be carried out at high temperature (the process temperature is higher than 1000 C), the coating type is single and the limitations are large, so its initial development is not satisfactory.
II. By the late 1970s, PVD(physical vapor deposition) technology had emerged.After that, PVD coating technology developed rapidly in a short period of 20 or 30 years. The reason is that PVD coating film is formed in the vacuum sealed cavity, which has almost no environmental pollution problems and is conducive to environmental protection. Because it can get bright, shoal surface, on color, mature have 7 color, argent, transparent color, golden yellow, black, and by golden yellow arrive any kind of color between black, it may be said is multicolored, can satisfy adornment sex all sorts of need; And because of PVD technology, can easily get other methods difficult to obtain high hardness, high wear resistance of ceramic coating, composite coating, applied in tooling, mold, can make life doubled, better to achieve the effect of low cost, high yield;In addition, PVD coating technology has the characteristics of low temperature and high energy, and can be used to form a film on almost any substrate. Therefore, it is not surprising that the PVD coating technology develops rapidly due to its wide application range. With the development of vacuum coating technology, PCVD(physical chemical vapor deposition), mt-cvd (chemical vapor deposition at medium temperature) and other new technologies have also appeared today. Various coating equipment and various coating processes are emerging in an endless stream.
III. At the same time, we should be aware that the development of vacuum coating technology is seriously unbalanced.Due to the extremely harsh working environment of tools and molds, the requirements for film adhesion are much higher than that of decorative coating. Therefore, although decorative coating manufacturers have been around, but the production of mold coating manufacturers are not many. Plus tool, mold coating the lack of after-sales service, so far, most domestic coating equipment manufacturers can provide complete cutting tool coating technology (including pretreatment process, coating process, coating post-processing technology, detection technology, the application of coating tool and mould technology, etc.), moreover, it also requires technology personnel, in addition to the master of professional knowledge of coating, also should have solid knowledge of metal material and heat treatment, mould coating surface pretreatment before the selection of proper knowledge, cutting tool, mold coating as well as the technical requirements for computer use, if any links appear problem, Will give users the conclusion that the use effect is not ideal. All these seriously restrict the application of this technology in cutting tools and moulds.
IV. on the other hand, because the technology is a between materials science, physics, electronics, chemistry and other disciplines of emerging edge discipline, and applied to the cutting tool, die domestic production in the field of one of the few leading manufacturers, mostly walk is a introduction of advanced equipment and technology from abroad, it remains to be a process of digestion, absorption, therefore, at present in the field of domestic technical force is out of proportion to its development, urgently needs to catch up.
V. PVD (Physical Vapor Deposition) is composed of vacuum evaporation Deposition, vacuum sputtering Deposition and vacuum ion Deposition. We usually say PVD coating, refers to the vacuum ion coating; NCVM coating is commonly referred to as vacuum evaporation coating and vacuum sputtering plating.
VI. The basic principle of vacuum evaporation: in the vacuum condition, the metal, metal alloy and so on are evaporated and then deposited on the surface of the substrate. The evaporation method is commonly used to heat the resistance and bombard the plating material with the electron beam to evaporate into the gas phase and then deposit on the surface of the substrate. In history, vacuum evaporation is the earliest technology used in the PVD method.
VII. Basic principle of sputtering coating: under the vacuum condition filled with argon (Ar) gas, argon is glow discharge. At this time, argon (Ar) atoms ionize into argon ion (Ar). Under the action of electric field force, argon ion accelerates bombarding the cathode target material made of the plating material, and the target material will be deposited on the workpiece surface by sputtering. The incident ions in the sputtering film are generally obtained by glow discharge in the range of l0-2pa ~ 10Pa. Therefore, when the sputtering particles fly to the substrate, they are easy to collide with the gas molecules in the vacuum chamber, making the motion direction random and the deposited film easy to be uniform.
VIII. Basic principle of ion plating: under vacuum conditions, some plasma ionization technology is adopted to partially ionize the atoms of the plating material into ions. At the same time, many high-energy neutral atoms are produced, and negative bias is added on the substrate. In this way, under the action of deep negative bias, ions are deposited on the surface of the matrix to form a thin film.
IX. Process of ion plating: particles of the evaporator, as high-energy ions with positive charge, are attracted by the high-pressure cathode (i.e. the workpiece) and injected into the workpiece surface at a high speed.
X. The process of ion plating is as follows:
The evaporating source is connected to the anode and the workpiece is connected to the cathode. A glow discharge is generated between the evaporating source and the workpiece after a high voltage direct current of three to five thousand volts is applied. As inert argon gas is filled in the vacuum cover, part of argon gas is ionized under the action of discharge electric field, thus forming a plasma dark area around the cathode workpiece. The argon ions with positive charge, attracted by the negative high pressure of the cathode, violently bombarded the surface of the workpiece, causing the surface particles and dirt of the workpiece to be splashed out, so that the surface of the workpiece to be plated was thoroughly cleaned by ion bombardment. Then, the evaporator is connected to the ac power supply, and the evaporator particles melt and evaporate, entering the glow discharge area and being ionized. Positively charged vaporizer ions, attracted by the cathode, rushed to the workpiece together with argon ions. When the number of vaporizer ions on the workpiece surface exceeded the number of splashed ions, they gradually piled up to form a coating that adhered firmly to the workpiece surface. This is the simple process of ion plating.
Comparison of three coating methods:
PVD technology has four technological steps
(1) workpiece cleaning: turn on the dc power supply, argon conducts glow discharge as argon ion, argon ion bombards the workpiece surface, and surface particles and dirt of the workpiece are splashed out;
(2) gasification of the plating material: after the alternating current is connected, the plating material is vaporized and gasified.
(3) migration of plating ions: atoms, molecules or ions supplied by the gasification source will rush to the workpiece at high speed after collision and high-voltage electric field;
(4) deposition of atoms, molecules or ions of the plating material on the substrate: when the amount of evaporating material ions on the surface of the workpiece exceeds the amount of spatter ions, it gradually accumulates to form a coating firmly adhered to the surface of the workpiece.
After particle ionization of ion plating, the evaporation material has three thousand to the kinetic energy of five thousand electron volts, high-speed bombardment artifacts, not only deposit speed is fast, and able to penetrate the surface, forming a deep into matrix diffusion layer, interface diffusion depth of ion plating would be four to five microns, that is to say, than the ordinary vacuum coating diffusion depth deep dozens of times, even one hundred times, and adhered to each other so fast.
XI. Basic concept and characteristics of PVD coating
PVD is an abbreviation of "Physical Vapor Deposition". We now generally vacuum evaporation, sputtering coating, ion plating and so on are called physical vapor deposition.
The more mature PVD methods mainly include multi-arc plating and magnetron sputtering plating. Multi-arc plating equipment is simple in structure and easy to operate. Its ion evaporates the source to be able to work by the electric welding machine power supply power supply, its starting arc process is also similar with the electric welding, in particular, under certain craft pressure, starting arc needle and evaporates the ion source short contact, disconnects, causes the gas discharge. Due to the cause of arc coating is mainly by means of moving arc spot, the evaporation source for formation of molten pool on the surface, make the metal evaporated, the film layer is deposited on the substrate, compared with the magnetron sputtering, it not only has the target material utilization rate is high, high ionization rate, more metal ions film the advantages of strong adhesion. In addition, the color of multi-arc coating is relatively stable, especially when TiN coating is made, the same stable golden color can be easily obtained in each batch, making the magnetron sputtering method unmatched. The disadvantage of multi-arc plating is that when the coating thickness reaches 0.3 m, the deposition rate and reflectance are close to each other under the condition of low-temperature coating with traditional DC power supply, and the film-forming becomes very difficult. Moreover, the surface of the film begins to blur. Another disadvantage of multi-arc plating is that, as the metal is evaporated after melting, the deposited particles are larger, resulting in lower density, and the wear resistance is worse than that of magnetron sputtering film formation.
It can be seen that both multi-arc coating and magnetron sputtering coating have advantages and disadvantages. In order to give full play to their respective advantages and realize complementarity, a coating machine integrating multi-arc technology and magnetron technology came into being. In the process, a new method of multi-arc plating is presented, which USES magnetron sputtering to thicken the coating, and finally USES multi-arc plating to achieve the final stable surface coating color.
About in the late 1980s, the emergence of hot cathode electron gun evaporative ion plating, hot cathode arc magnetron plasma coating machine, the application effect is very good, so that TiN coating tool quickly get universal application. Among them, the hot cathode electron gun evaporative ion plating, using copper crucible heating melting is gilded material, using tantalum filament to heat the workpiece, degassing, using the electron gun to enhance the ionization rate, not only can get the thickness of 3~5 m TiN coating, but also its adhesion, wear resistance are good performance, even by grinding method is difficult to remove. But these devices are only suitable for TiN coating, or pure metal film. For multi-coating or composite coating, it is difficult to adapt to high hardness material high-speed cutting and mold application diversity requirements.
CemeCon at present, some developed countries (such as Germany, the UK ART - TEER, Swiss Platit) on the basis of the traditional principle of magnetron sputtering, unbalanced magnetic field instead of the original balance of magnetic field, 50 KHZ medium frequency power supply to replace the original dc power supply, pulse power supply instead of dc bias, the auxiliary anode technology etc, make the magnetron sputtering technology is gradually mature, has large quantities of used on mould coating, is now stable production mainly include TiAlN, AlTiN coating, TiB2, DLC, CrN, China guangdong, jiangsu, guizhou, zhuzhou and other places have also introduced this kind of equipment, has the potential of catching fire.
XII. PVD flow chart
PVD machining characteristic
1) PVD film can be directly plated on stainless steel and hard alloy. The relatively soft zinc alloy, copper, iron and other die castings should be electroplated with chromium first, and then suitable for PVD plating.
2). Typical PVD coating processing temperature between 250 ℃ -- 450 ℃;
3) coating type and thickness determine the process time, the general process time is 3~6 hours;
4) PVD coating layer thickness of micron level, with thin thickness, average of 0.3 mu m ~ 5 microns, the decorative coating membrane layer thickness is commonly 0.3 mu m ~ 1 mu m, so it can be almost does not affect the original size of the workpiece raise all kinds of physical properties and chemical properties on the surface of the workpiece, and can maintain the workpiece size, need not again after plating processing;
5).PVD technology not only improves the bonding strength between the coating film and the substrate material, but also develops the coating composition from the first generation of TiN to the composite coating of TiC, TiCN, ZrN, CrN, MoS2, TiAlN, TiAlCN, tin-aln, CNx, DLC and ta-c, forming the surface effect of different colors.
6) the current available film colors are dark gold, light gold, brown, bronze, gray, black, grey-black, seven-color, etc. The color can be controlled by controlling the parameters in the plating process. At the end of the coating can be used to measure the color value of the relevant instruments, so that the color can be quantified, to determine whether the color plating meets the requirements.
The application of PVD coating technology is mainly divided into two categories: decorative plating and tool plating:
The purpose of decorative plating: mainly in order to improve the appearance of the workpiece decorative properties and color, at the same time make the workpiece more wear and corrosion resistance to extend its service life; This aspect mainly applies the hardware profession each domain, if the door window hardware, the lock, the bathroom hardware and so on industry.
The purpose of tool plating: mainly in order to improve the surface hardness and wear resistance of the workpiece, reduce the friction coefficient of the surface, improve the service life of the workpiece; This aspect is mainly used in various cutting tools, turning tools (such as turning tools, planer knives, milling cutters, drill bits, etc.) and other products.
Although the use of PVD coating technology can be plated out of high-quality film, but the cost of PVD coating process is actually not high, it is a very cost-effective surface treatment, so in recent years PVD coating technology is developing very fast. PVD coating has become the development direction of surface treatment in hardware industry.
XIII. PVD Advantage
1. Good adhesion of coating
Ordinary vacuum coating, the surface of the workpiece and coating almost no connection between the transition layer, as distinct. Ion plating, ion bombardment high-speed artifacts, able to penetrate the surface, forming a deep into matrix diffusion layer, interface diffusion depth of ion plating would be four to five microns, after ion plating of the specimen for tensile test showed that all the way to going to fracture, plating with matrix metal plastic elongation, without peeling or flaking off, visible how strong adhesion, membrane layer uniform, dense.
2. Good wrapping and plating ability
In the case of ion plating, the evaporator particles move along the direction of the power line in the electric field in the form of charged ions. Therefore, wherever there is an electric field, a good coating can be obtained, which is much superior to the ordinary vacuum coating which can only be obtained in the direct direction. Therefore, this method is very suitable for the plating of parts on the inner hole, groove and narrow slot. Other methods difficult to plating parts. With ordinary vacuum coating can only be plated directly on the surface, evaporation particles, such as climbing ladder, can only follow the ladder; Ion plating, on the other hand, can be evenly wound around the back of the part and into the inner hole. Charged ions, on the other hand, can be transported to any place within the radius of the specified flight path, just like in a helicopter.
3.The coating is of good quality
The coating has compact structure, no pinhole, no bubble and uniform thickness. Even the edges and grooves can be plated evenly without forming metal nodules. Parts like thread can also be plated, with high hardness, high wear resistance (low friction coefficient), good corrosion resistance and chemical stability, film life longer; At the same time the film can greatly improve the appearance of the workpiece decorative performance
4.Cleaning process simplification
Existing coating process, most of the requirements of prior to the workpiece for strict cleaning, both complex and trouble. However, the ion plating process itself has an ion bombardment cleaning effect, and this effect has been continued throughout the coating process. Excellent cleaning effect, can make the coating directly close to the substrate, effectively enhance the adhesion, simplify a lot of cleaning before plating.
5. Wide range of plating materials
Ion plating is the use of high-energy ions bombarding the surface of the workpiece, so that a large amount of electrical energy on the surface of the workpiece into heat energy, thus promoting the surface tissue diffusion and chemical reaction. However, the whole workpiece, especially the core of the workpiece, was not affected by the high temperature. Therefore, this kind of coating process has a wide range of applications, and the limitations are small. In general, all kinds of metals, alloys and some synthetic materials, insulation materials, thermal materials and high melting point materials can be plated. Can be plated on the metal workpiece nonmetal or metal, also can be plated on the nonmetal or nonmetal, and even can be plated on plastic, rubber, quartz, ceramics and so on.
Application scope, advantages and disadvantages of two-color PVD technology.
Its application scope is:
1) carbon steel, alloy steel, stainless steel, titanium alloy and other metal materials;
2) the surface hardness of the metal material should be at least HV170.
Its advantages are:
Compared with the traditional magnetron sputtering monochrome PVD technology, the two-color PVD technology is more complex, more complex, and more difficult to produce, but it has excellent appearance effect. The surface hardness of both colors is above HV600.
The traditional magnetron sputtering monochrome PVD technology is to achieve the two-color effect. The technological measures taken are to carve out or grind out the laser in the region that needs to achieve another color on the basis of the whole PVD monochrome. The area that new treatment comes out can show the instinctive quality of the metal only, surface hardness namely the surface hardness of metal itself --
The surface hardness after PVD is above HV600).
Its disadvantages are:
1) the process is more complex than the traditional monochrome PVD, and the process is more complex and difficult to produce;
2) the production yield is low, about 65 ~ 70% (the yield of traditional monochrome PVD is generally 85 ~ 90%;
3) the price will be 50 ~ 60% higher than the traditional monochrome PVD;
4) due to the influence of technology and process, the production of two-color PVD has more restrictions and is greatly affected by the product structure, while the traditional monochrome PVD is almost unlimited
Modern coating equipment (uniform heating technology, temperature measurement technology, unbalanced magnetron splash, auxiliary anode, intermediate frequency power supply, pulse technology) modern coating equipment is mainly obtained by vacuum chamber, vacuum part, vacuum measurement part, power supply, process gas input system, mechanical transmission parts, heating and temperature measuring unit, ion evaporation or sputtering source, water system and other parts.
1 the vacuum chamber
Coating equipment mainly has continuous coating production line and single room coating machine two forms, because the mold coating heating and mechanical transmission part has higher requirements, and mold shape, size vary, continuous coating production line is usually difficult to meet the requirements, must use a single room coating machine.
2 Vacuum gain part
Vacuum acquisition is an important part of vacuum technology. Due to the requirements of high adhesion of the coating on the workpiece, the background vacuum degree should be better than 6mPa before the start of the coating process, and even up to 0.06mPa after the completion of the coating process. Therefore, it is very important to select the vacuum acquisition equipment reasonably to achieve high vacuum degree. As of now, there is no pump that can operate from atmospheric pressure all the way up to near ultra high vacuum. Therefore, the acquisition of vacuum is not a vacuum equipment and methods can achieve, must be used in combination with several pumps, such as mechanical pump, molecular pump system.
3 Vacuum measuring part
The vacuum measurement part of the vacuum system is to measure the pressure in the vacuum chamber. Like the vacuum pump, no vacuum gauge can measure the entire vacuum range, so many kinds of vacuum gauges have been made according to different principles and requirements.
4 Power supply
Target power supply mainly includes dc power supply (such as MDX) and intermediate frequency power supply (such as PE, PEII and PINACAL produced by AE company in the United States). The workpiece itself is usually supplied with a dc power supply (such as MDX), a pulse power supply (such as PINACAL+ produced by AE), or an RF power supply (RF).
5 Process gas input system
Process gases, such as argon (Ar), krypton (Kr), nitrogen (N2), acetylene (C2H2), methane (CH4), hydrogen (H2), oxygen (O2), etc., are generally supplied by cylinders, through the gas reducing valve, gas globe valve, pipeline, gas flowmeter, solenoid valve, piezoelectric valve, and then into the vacuum chamber. The advantage of this gas input system is that the pipeline is simple, bright, easy maintenance or replacement of cylinders. Each coating machine does not affect each other. There are also cases where multiple coating machines share a set of cylinders, which may be seen in some of the larger coating shops. Its advantage is, reduce gas cylinder to occupy dosage, unified program, unified layout. The downside is that the number of connections increases the chance of leakage. Moreover, the coating machine will interfere with each other, a coating machine pipeline leakage, may affect the quality of other coating machine products. In addition, when replacing cylinders, it is necessary to ensure that all the hosts are in a non-gas state.
6 Mechanical drive
Tool coating requires uniform thickness around the edge, so there must be three rotations in the coating process to meet the requirements. That is, while the large workpiece table is required to rotate (I), the small workpiece carrier table also rotates (II), and the workpiece itself can rotate simultaneously (III).
In mechanical design, usually in the center of the large workpiece turntable bottom for a large driving gear, surrounded by some small star gear meshing with it, and then use a fork to dial the workpiece rotation. Of course, when making the mold coating, it is usually enough to have two rotations, but the bearing capacity of the gear must be greatly enhanced.
7 Heating and temperature measuring part
When coating the work model, how to ensure the uniform heating of the plated workpiece is much more important than decoration coating heating. Die coating equipment are generally before and after two heaters, thermocouple temperature measurement and control. However, because the thermocouple clamps are different, the temperature reading cannot be the real temperature of the workpiece. There is a lot of ways to measure the actual temperature of a workpiece. Here is a simple Surface Thermomeer method. The thermometer works by expanding the spring at the bottom when the thermometer is heated, causing the needle to push the positioning needle to rotate until it reaches the maximum temperature. When the temperature drops, the spring contracts and the pointer rotates in the opposite direction, but the positioning pointer remains at the highest temperature. After opening the door, read the temperature indicated by the positioning pointer, that is, the highest temperature value once reached by the surface thermometer when it is heated in the vacuum chamber.
8 Ion evaporation and sputtering sources
The evaporation source of multi-arc plating is generally round cake shape, commonly known as round cake target. In recent years, rectangular multi-arc target has also appeared, but no obvious effect has been seen. The round cake target is mounted on the copper target seat (cathode seat), and the two are connected by ridges. There is a magnet in the target seat. By moving the magnet back and forth, the magnetic field intensity can be changed, and the moving speed and track of the arc spot can be adjusted. In order to reduce the temperature of the target and the target seat, the target seat should be continuously fed with cooling water. In order to ensure the high conductivity and thermal conductivity between the target and the target seat, the Sn gasket can be added between the target and the target seat. Magnetron sputtering coating generally USES rectangular or cylindrical targets,
9 water cooling system
Because in order to improve the ionization rate of metal atoms, each cathode target is designed to use large power output as much as possible, which requires sufficient cooling. Moreover, many kinds of coating in the mold coating, heating temperature is 400~500 C, therefore, on the vacuum chamber wall, the cooling of each sealing surface is also very important, so the cooling water had better use about 18~20 C chiller water supply. In order to prevent water droplets from precipitating out of the low-temperature vacuum chamber wall and cathode target in contact with hot air after opening the door, about 10 minutes before opening the door, the water-cooling system should be able to switch to the heating water state, and the hot water temperature is about 40~45 C.
XIV. Working steps of mould and die PVD
The basic process flow of die PVD can be summarized as follows: IQC pretreatment PVD FQC.
The main work of IQC(InQuality Control) is not only to check the quantity routinely and check whether the drawing is consistent with the real object, but also to carefully check the workpiece surface, especially whether there are cracks and other defects at the cutting edge. Sometimes for some of the cutting tools, the blade, in the body of the microscope observation, more convenient to find problems; In addition, the personnel of IQC should also pay attention to check whether the coating parts have plastic, solder with low melting point, etc., if these things are mixed into the coating process due to the omission of inspection, it will seriously release air in the vacuum chamber, which may cause the whole batch of products to be decoated, or even cause the original OK products to be scrapped, and the consequences will be unthinkable.
2 Pretreatment process (steam gun, sandblasting, polishing, cleaning)
The purpose of pretreatment is to purify or rough the surface of chemical parts.
Purification is to remove all kinds of surface contamination, preparation of clean surface. Purification by mechanical, physical, or chemical means, usually with a variety of purifying agents. Coarsening, as opposed to photoetching, aims at preparing rough surfaces to enhance the structural strength of the coating or coating decoration. We now have the main pretreatment methods: high temperature steam cleaning, cleaning, sandblasting, grinding, polishing and other methods.
High temperature steam washing
At present, PVD workshop commonly used high temperature steam cleaning equipment is steam gun. Its maximum operating temperature can reach 145 degrees, and the air pressure is around 3~5 bar. Because the mold often contains some small holes, threaded holes, often oil, residual coolant and other impurities in the hole, the conventional cleaning method is difficult to remove. At this point, the high temperature steam washing equipment can maximize its advantages. cleaning
XV. The cleaning procedures of die coating before each factory are as follows:
1. Ultrasonic wax removal 2. Over water 3. Ultrasonic oil removal 4. Over water 5. Ultrasonic replacement 6. Over water 7. Over pure water 8. This is because the decorative coating substrate is mostly stainless steel or titanium alloy, not easy to rust. In addition, decorative coating on watermarks, spots and other defects are absolutely not allowed. Therefore, decorative coating to the water quality requirement of the pure water is extremely high, and even to reach more than 15 m Ω. To ensure the high quality of cleaning, can be repeated cleaning, and in the high quality of pure water and ultrasonic immersion for a long time to get. However, die cleaning is different, especially some hot die steel, if like decorative coating to clean, will rust in a mess.
Because of the mould coating of the surface of the original state, in addition to some high standard lens mold, generally more decorative coatings are rough, therefore, on the surface of the coating after state requirements are not as high as decorative coating, this allows us to take water quickly, with dry, oil-free compressed air to blow dry, then the factory mold drying method to deal with strong winds. And those high standard mirror mold, are generally 136 stainless steel, can borrow decorative coating cleaning method.
In a word, the cleaning method before the die coating depends on the different materials used by the die, the surface state before the die coating is different, and not the same.
The following is a few materials rust from difficult to easy sort, for reference:
Stainless steel, hard alloy, metal ceramic alloy, DC53, high speed steel, 8407 have an automatic cleaning machine model CR288, made in Germany. The maximum cleaning capacity of this machine is 80KG, mainly used for cleaning tools, small parts, or small size of the mold. It has a total of three cleaning cylinder, the solution is tap water + cleaning agent, tap water, deionized water. In addition to the common ultrasonic, water washing, spray, swing, hot air drying and other functions, the machine is another advantage is the final set of vacuum steps, can make the moisture as soon as possible volatile.
Automatic cleaning machine memory ten kinds of technology, are preset by the supplier. One to nine can be used for different types of products, different surface state purification treatment. The tenth is used for cleaning agent.
Sand blasting is the use of compressed air to make abrasive strong erosion workpiece surface, so as to remove rust, carbon deposition, welding slag, oxide, residual salt, old paint layer and other surface defects. Sand blasting can be divided into dry sand blasting and wet sand blasting according to the conditions of abrasive use.
The technological parameters of sand blasting mainly include gun distance, inclination Angle, rotating speed, moving speed, stroke, round trip times, sand blasting time and sand blasting air pressure. The parameters we have used are gun range: 30~70mm; Angle of 30 ~ 70? C; The rotating speed of the clamping table is 10~30; Round trip times: 3~9 times; Sand blast pressure: 1.8~3.5 bar, etc. In the specific operation, the upper and lower limits are selected according to the degree of dirt on the workpiece surface, the hardness of the workpiece, the geometry of the workpiece surface and other factors. The abrasive we choose in the dry sandblasting machine is glass beads, suitable for spraying some hardness medium materials, such as oil steel, mold, etc. In the liquid sandblasting machine selected abrasive alumina, high hardness, suitable for some high hardness of the material, such as hard alloy material. Abrasive size is also important for die coating. If the abrasive size is too large, the workpiece surface is too rough; If the particle size of abrasive is too small, and will reduce the impact force, or even embedded in the workpiece surface, cleaning is difficult to remove, so that the workpiece coating adhesion is reduced. For this reason, some European countries, on the die coating before blasting abrasive particle size used to do A careful study, strict enough to ensure that more than 85% of the grain size in the A, B point range before use. In contrast, China's abrasive suppliers are still lack of consensus in this regard, we also rarely do this test.
PVD coating process (heating, ion cleaning, coating, cooling, process gas, air pressure, temperature, sputtering power) FQC
1. Function Quality Control 2. Function Quality Control 2. The content of FQC mainly includes methods of appearance inspection, layer depth inspection, adhesion inspection, wear resistance inspection, corrosion resistance inspection and simulation test. I plant the main application of the current appearance inspection, layer depth inspection and adhesion inspection.
As most of the products we come into contact with are not allowed to do destructive inspection, we will put in the sample with each batch when coating. When you do a depth test and a adhesion test, in most cases, you're actually checking the sample with the batch. Since it is difficult to agree between the sample and the product in terms of raw materials, heat treatment status, clamping position, etc., there will be certain error between the detected result and the actual value of the product. Sometimes there may be considerable error, can only be used as a reference. Of course, when necessary, we can also make simulation parts to achieve the purpose of accurate measurement.
Open the door for the product, the surface should be carefully checked for cracks, coating, loose and other defects. For knives, knives, also need to carefully examine the state of their blades under the microscope.
Layer deep check
There are many methods for depth inspection, such as microsection metallography, X-ray examination, optical test with monochromatic light as the light source, ball mill test and so on. The layer depth inspection of die coating is carried out on a ball mill. The method is to use a steel ball with a diameter of 10mm to test the surface rolling grinding, and then measure the relevant data of the grinding marks under the microscope, and put it into the formula to calculate the depth of the layer.
This kind of layer depth examines the characteristic of the method is: convenient and applicable, error is largo. But this error applied to die above the impact will not be too large. Interested colleagues may also refer to the relevant literature.
There are a lot of adhesion inspection methods, each factory according to the characteristics of their products, have developed the corresponding test methods. Among them, there are two authoritative methods. One is to do indentation test with conical diamond head on rockwell hardness tester, observe under the microscope, and judge the adhesion of the coating by the number of cracks around the indentation. This method has high requirements for the shape of the diamond head. It not only strictly requires the center point to be in the center of the circle, but also requires the roundness of the diamond cone to be very regular. Unfortunately, at present, China does not have its national or industry standards; Another method is the scratch method, some of our coating launched earlier scientific research departments, is also the use of this method, there are special national industry standards for query.
Besmear after processing technology of jig (sandblasting, painting fat technology) detection technology (binding force test, the deep layer of detection, acid corrosion) coating stripping technology (TiAlN/TiN stripping technology, CrN/DLC/CrAlTiN stripping technology, the surface of the cemented carbide coating stripping technology) application technology of the coated tools (in the proper selection of coating, coating tool used correctly
Coating on the tool optimization is very big, because the high speed cutting machining than the traditional cutting temperature is higher, the application of coating, can play its role in high temperature, oxidation resistance and hardening materials. For example, chromium nitride (CrN) coatings reduce friction coefficients and improve finish and chip removal.
XVI. Specification of main technical requirements
1. Double-color PVD matching selection is conducted between traditional and conventional colors such as black, silver, gold and common rose;
2. Two-color PVD pairing on or between 3D surfaces is not allowed;
3. Two-color PVD design can be carried out on 2D plane structure;
4. As far as the current technical conditions are concerned, it is limited to common and regular colors, such as black, silver, gold and common rose. Two-color PVD matching selection is conducted between traditional and conventional colors such as black, silver, gold and common rose.
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