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Electroless nickel plating for industrial applications

Number of visits: Date:2016-12-30 17:05

As the electroless nickel plating layer has excellent uniformity, hardness, wear resistance and corrosion resistance and other comprehensive physical and chemical properties, the technology has been widely used, it is almost impossible to find an industry does not use electroless nickel plating technology. It is reported that the proportion of electroless nickel plating in various industries is as follows: aerospace industry: 9%, automobile industry: 5%, electronic computer industry: 15%

Food industry: 5%, machinery industry: 15%, nuclear industry: 2%, oil industry: 10%, plastic industry: 5%, power transportation industry: 3%, printing industry: 3%, pump manufacturing: 5% Valve manufacturing industry: 17%, other: 6%. The application of electroless nickel plating in the world's industrialized countries has experienced unprecedented development in the 1980s, with an average annual net growth rate of 10% to 15%. The application of electroless nickel plating is expected to continue, with an average annual net rate of about 6% , And into the mature period of development. In the booming economy of East Asia and the southeast region, including China, chemical plating applications are on the rise stage, is expected to remain an unprecedented high-speed development.

First, the aerospace industry

The aerospace industry is one of the major users of electroless nickel plating. The more prominent examples are the Oklahoma Air Logistics Center, which since 1979 and Northwest Airlines have used electroless nickel plating to repair aircraft since 1983 Engine parts. Pratt & Whitney's JT8D jet engine has been discontinued, but so far there are still thousands of such engines used in the Boeing 727 and McDonnell Douglas DC-9 aircraft, because: a high-phosphorus, compressive stress Electroless nickel plating is used to repair the impeller of the JT8D six types of jet engines to ensure the re-use of this engine. In the aeroengine turbine or compressor blades, usually nickel-phosphorus alloy chemical plating thickness of 25 ~ 75um, to prevent gas corrosion, the fatigue strength of less than 25% lower than the chrome plating. Oklahoma Airlines Logistics Center uses ultra-thick layer of electroless nickel plating repair aircraft parts, plating thickness of 275 ~ 750um. The original use of electroplating process rework rate of 50%, the use of electroless nickel after the pass rate of 90% or more, showing significant economic benefits. Auxiliary generator (APU) on the aircraft by electroless nickel, its life increased by 3 to 4 times. Weighs 8.2 tons of the main bearing surface of the turbine engine by nickel plating 100um, to prevent the boot and shutdown caused by vibration damage. In order to reduce the weight of the aviation industry, the use of aluminum alloy parts, the electroless nickel plating surface after strengthening not only corrosion, wear, and welding, such as stroke engine piston head after electroless nickel plating to improve the service life. There are other titanium alloy parts, beryllium alloy are used low stress and compressive stress of the chemical nickel plating surface protection and other measures. Nickel + Thallium-Boron Ternary Alloy Electroless Plating (NTB) is designated as a surface hardening process for more than 160 parts of the Pratt & Whitney jet engine for abrasion and fretting wear, for example: NTB electroless plating Sealed in the jet engine spindle. The US Air Force asked the engine manufacturer to provide a 4,000-tactical cycle with a wear rate of 0.178 mm, which must be dismantled and repaired. The NTB electroless plating has significantly reduced the wear on the spindle seal, with a wear rate of about 0.008 after 4000 tactical cycles Mm. Aerospace system widely used metal light microscope, the matrix for the high strength, light weight beryllium or aluminum, by special chemical nickel plating surface strengthening, the phosphorus content of 12.2% to 12.7% of the electroless nickel can be polished to 9? , Such a high precision in the need for low inertia of the universe, with excellent performance. China's chemical plating industry, although the late start, but since the nineties through the unremitting efforts of scientific research units, now has a mature technology and experience in China's Luoyang has been built mechanical parts electroless nickel plating processing lines.

Second, the automotive industry

Solve the use of ethanol, gasoline mixed fuel problem is one of the development trend of the automotive industry, the use of mixed fuel, in addition to performance problems, but also produced a fuel system corrosion problems. In Brazil, the use of ethanol as fuel, the application of electroless nickel plating technology to protect zinc die castings, such as carburetor from corrosion has become a process specification. In the United States, when widely used methanol or methanol and gasoline mixed fuel, the automotive industry is bound to apply electroless nickel as a vaporizer, fuel pump system surface protection means. Differential planetary gear is an important part of the car, coated with 25um thick electroless nickel layer to improve wear resistance, and some car manufacturers in the shaft using polytetrafluoroethylene composite electroless nickel plating process, this compound The coating has a certain hardness, but also a good lubrication performance, improve the service life of the shaft. The automotive industry utilizes the advantage that electroless nickel plating is very homogeneous and is protected by chemical plating on complex parts such as gears, heat sinks and injectors. Coated with about 10um of the electroless nickel plating layer of aluminum radiator has a good brazing. The size of the electromechanical plating on the gear is very easy to maintain at ± 0.3 to 0.5 μm. And if the use of electroplating process, you must also be processed after plating to achieve a qualified range of work. The electroless nickel plating on the injector can provide good resistance to corrosion and wear of the fuel. Often, fuel corrosion and wear can lead to the expansion of the injection hole, so the fuel injection increases, so that the engine horsepower beyond the design standards to speed up the engine damage. Electroless nickel plating can effectively prevent the corrosion of the injector, wear, improve the reliability of the engine and service life.

Third, the chemical industry

Chemical Industry Application Study Electroless nickel plating technology replaces expensive corrosion resistant alloys to solve corrosion problems in order to improve the purity of chemical products, protect the environment, improve operational safety and the reliability of production and transportation, so as to obtain more favorable technical and economic competitiveness. Electroless plating is widely used in the protection of inner walls of large reaction vessels. Originally very interesting application examples are: 1955 US General Transportation Company (GATX) using chemical plating tank to protect the inner wall, to prevent caustic alkali corrosion. Today, electroless nickel plating technology has made great progress, can be in a variety of chemical corrosion environment to provide reliable protection. The most widely used electroless nickel plating is the valve manufacturing industry. Steel ball valve, gate valve, rotary valve, check valve and butterfly valve, etc., by high phosphorus electroless nickel plating 25 ~ 75um, can improve the corrosion resistance and service life. Chemical pump with the effect of electroless nickel plating is also significant. In the caustic alkali corrosion conditions of the valve, should be coated with phosphorus content of 1% to 2% of low phosphorus electroless nickel plating. Because the corrosion rate of the low-phosphorus electroless nickel plating layer is about 2.5um under the caustic alkali corrosion condition, it is better than that of the phosphorous or high phosphorus electroless nickel plating layer. Electroless nickel layer in the strong oxidizing acid, such as concentrated nitric acid, concentrated sulfuric acid and other media is not corrosion. Although the corrosion rate in hydrochloric acid is lower than that of austenitic stainless steel, corrosion resistance is still insufficient. Therefore, it is not preferable to use an electroless nickel plating layer for the above-mentioned strong acid medium, or a medium which may be hydrolyzed to produce the above strong acid. Carbon steel fasteners plated with 25 ~ 50um thick high phosphorus electroless nickel plating layer, instead of stainless steel fasteners, not only to overcome the austenitic stainless steel stress corrosion cracking problem, but also save a lot of costs. Production of low density polyethylene pressure vessel inner wall 25um to prevent iron contamination and consequently the resulting discoloration of polyethylene. If the use of stainless steel construction, the price is about twice the chemical plating method.

Four, oil and gas

Oil and natural gas is one of the important markets for electroless nickel plating. Oilfield oil and oil pipelines are widely used in electroless nickel plating. Typical oil and natural gas industry corrosive environment for the underground salt water, carbon dioxide, hydrogen sulfide, the temperature up to 170 ~ 200 ℃, accompanied by sediment and other abrasive erosion, etc., corrosion environment is quite bad. Low carbon steel oil and gas pipelines in such a harsh conditions, only 2 to 3 months of life. After 50 ~ 100um thick high-phosphorus electroless nickel layer protection, the corrosion rate reduced to a considerable degree of Hastelloy. Taking into account the expensive corrosion-resistant alloy, from the performance and price ratio, carbon steel pipe with electroless nickel plating to protect the technical and economic performance of the best. Pump shell, impeller and outlet piping and other oil and gas pump parts, according to different corrosion environment, the chemical nickel plating thickness of 25 ~ 75um range, anti-corrosion effect is excellent. Pumping pump Electroless nickel plating is an ideal application example: In the West Texas oil field, the electroless nickel plating pump, life of up to 4 years, the same protection of the pump life of not more than 6 months. Electroless nickel plating is resistant to wear and tear, and because of the high degree of uniformity of the electroless nickel plating layer, the pump barrel can be made into a single piece, which significantly improves the quality of the pump and reduces the production cost. In the oil field, high phosphorus electroless nickel plating is also widely used in oil and water separation device heater surface to prevent corrosion, plating thickness is usually 25 ~ 75um. Oil and oil piping valves, pipe joints, pipe hoop, etc. are also used to protect the nickel plating.

Fifth, food processing industry

The food processing industry provides a huge potential market for the application of electroless nickel plating; it is called a potential market because there is an obstacle to the widespread use of chemical nickel plating in the food industry. For example, in the United States, FDA (US Food and Drug Administration) for the application of electroless nickel plating in the food industry has yet developed a regulatory standard; usually, for the application of electroless nickel layer in direct contact with food, FDA to take a case Processing to be approved. The reason is mainly because the classic chemical bath formula containing toxic lead, cadmium and other heavy metal ions as a stabilizer reason. However, many modern electroless nickel plating solutions do not use heavy metal ions as stabilizers; it is clear that this barrier will soon be removed. At present, food packaging machinery is not in direct contact with food parts, such as: bearings, rollers, conveyor belts, hydraulic systems and gears for the chemical nickel plating in the food industry in the typical application. In the food processing process, will involve salt water, nitrite, citric acid, acetic acid, natural wood smokes, volatile organic acids and other corrosive media and other issues; food processing temperature range of 60 to 200, the production environment relative humidity High; in such conditions, food processing equipment, there are metal corrosion, fatigue and wear and other issues. In the case of contact with food metal surface, the traditional protection method is electroplating hard chrome; However, in the chloride ion acidic medium, the chrome plating layer corrosion resistance is not good; however, electroless nickel plating in the plating capacity, high corrosion resistance , Anti-stick, mold release, etc. has obvious advantages. Nickel is used in contact with food parts of the chemical nickel plating is one of the successful examples of application; other in the food inflatable canning machine, screw feeder, spices pot, food mold, baking pan, drying oven, bread insulation furnace The higher the use of electroless nickel plating on food machinery.

Six, mining industry

Mining industry environmental conditions are bad, underground machinery inevitably contact with salt water, mineral acid, to be tested by corrosion and wear. Therefore, mining machinery requires surface protection. Mine roof support system, the commonly used hard chromium plating as a hydraulic pillar anti-corrosion wear-resistant protective layer. However, due to the surface of the hard chrome cracks, porous, often used because of corrosion so that the hydraulic pillars were killed and unable to move. This problem of high pressure hydraulic cylinders is more serious. In the high-pressure work, the coating is stretched, making the high stress hard chromium layer cracks further intensified. In this case, the use of 25um thick compressive stress of high-phosphorus electroless nickel plating layer to do protection, when the hydraulic pillars by high-pressure drawing, the electroless nickel layer will not crack, and can withstand the underground coal mine corrosion and wear The In some open-pit mining production, such as the use of phosphate rock for fertilizer, high pressure pumps and jet nozzles are used. At this point, the corrosion and erosion problems are severe, but the application of corrosion resistant wear-resistant electroless nickel plating It can prevent premature damage to mechanical parts.

Seven, military industry

Electroless nickel plating technology has been widely used in military applications, highlighting examples of electroslag nickel protection on aircraft carrier ejection hoods and rails. The working environment of the ejection machine is very bad, the high-temperature airflow of the aircraft when the aircraft flush the track, ejection when the huge force, marine weather conditions corrosion, making the ejection system can only use 6 to 12 months. Now the surface treatment process is: the correct pretreatment of the ejection hood, after plating nickel, electroless nickel 100um, and then electroplated cadmium 12.5um, and passivation of chromic acid. This composite coating protective layer, with good wear and anti-micro-vibration wear performance, ejection system life can be extended to 14 to 18 years, that is, an increase of 18 times. Military trunks for years have been protected by electroless nickel plating to prevent corrosion and wear of road mud and brine. Tank rearview mirror made of aluminum, refined grinding, the electroless nickel plating as a corrosion-resistant wear-resistant protective layer. Technical requirements Rearview mirrors have a reflectivity of 80% in the visible spectrum, and the electroless nickel plating is easy to meet these optical requirements. Aluminum Radar Waveguide Plated with 25um thick electroless nickel plating to prevent land and sea corrosion. Electroless nickel plating uniformity, to meet the technical requirements of a variety of waveguide.

Eight, electronics and computer industry

Electroless nickel plating is the most widely used in the electronics and computer industries, covering virtually every electroless nickel plating technology and process. Many of the new electroless nickel plating processes and materials have been developed in light of the needs of the electronics and computer industry. In terms of technical performance, in addition to resistance to wear and tear, but also has a welding, non-proliferation, electrical properties and magnetic properties and other requirements. Some countries have established regulations: electronic equipment must be shielded to prevent electromagnetic and radio frequency interference. Electronic equipment on the plastic shell on the copper, and then electroless nickel, such a bimetallic coating, is recognized as one of the most effective way to shield. Electroless nickel plating is one of the key steps in the manufacture of computer thin film hard disks. Mainly in the fine processing of 5086 magnesium aluminum surface plating 12.5um thick nickel-phosphorus alloy layer for the follow-up vacuum sputtering magnetic recording film to prepare. The electroless nickel plating layer has a phosphorus content of 12% wt (atomic percent about 20.5%). The coating must be low stress and compressive. Heated at 250 ° C or 300 ° C for 1 h, while maintaining a non-magnetic property, i.e., the remanence is less than 0.1 × 10-4T. The coating must be uniform and smooth, and any defects and protrusions on the surface shall not exceed 0.025um. Because of the high technical requirements, it is necessary to use high-quality and high-clean special chemical plating solution, automatic plating control equipment and high cleanliness of the workshop environment. Computer thin film hard disk Electroless nickel plating is a typical representative of high-tech electroless nickel plating, occupying a very important market share. Electroless nickel plating technology in the microelectronic device manufacturing industry is growing rapidly. It has been reported that Xerox has adopted selective nickel-phosphorus alloy electroless plating in the interconnection of ultra-large-scale integrated circuit multilayer chips and via-hole leveling processes; its products have passed anti- Shear strength, tensile strength, high and low temperature cycle and the electrical properties of the test. Practice shows that the application of electroless nickel plating technology to improve the microelectronic device manufacturing process technology and product reliability and reliability.

Nine, other industry

Injection molding machine, die-casting mold, and other models are mechanical, light industry, a wide range of products. As the mold geometry is complex, when the use of electroplating method to strengthen the mold surface, in order to make all sides can be plated, you must design and installation of complex auxiliary anode and hanging; Dimensional accuracy and surface roughness requirements; Moreover, the electroless nickel plating layer has a low coefficient of friction and outstanding mold release performance, making it one of the most cost-effective mold surface treatment technology. Casting models and core boxes are usually cast iron or cast aluminum parts, in the course of the use of abrasive wear, scrapped quickly. After the use of electroless nickel-nickel surface protection, the casting model and the quality of the core box on the grade, significantly improve the service life. Textile machinery speed is very high, all kinds of fiber yarn for the mechanical parts of the wear and tear is very serious. Electroless nickel plating, especially artificial polycrystalline diamond composite electroless plating technology, has successfully solved the problem of wear of textile machinery parts. Printing machine on a variety of rollers and components, using 25 ~ 50um thick electroless nickel layer protection to prevent printing ink and white liquor corrosion. The uniformity of the electroless nickel layer ensures the dimensional accuracy of the printing roll without the need for post-plating machining. Some medical devices such as surgical wrenches, dental drill and medical molds have been replaced by electroless nickel plating on original metal plating.

------ Zhengzhou Light Research Alloy Technology Co., Ltd. can provide aerospace and other applications of electroless nickel plating, improve product performance and service life.

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