Current situation and development of brazing and d

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Current situation and development of brazing and diffusion welding at home and abroad. At present, the production of brazing materials belongs to the non-ferrous metal industry, while welding electrodes belong to the ferrous metal industry. Although there are great differences between the two industries, they also have a lot in common. Brazing and diffusion welding technology, among the 23 professional committees of the former China Welding Association (now adjusted to 13), is one of the most active and potential professional fields in recent years

since the "7th National Welding academic conference" held by the Chinese welding society in Qingdao in 1993, the brazing Committee has held the 7th, 8th and 9th National brazing and diffusion welding technology exchange conferences in Jinhua City, Zhejiang Province, Dayong City, Hunan Province and Yangzhong City, Jiangsu Province in 1994, 1995 and 1996 respectively, especially the 10th National brazing and diffusion welding technology exchange conference held in Wuxi, Jiangsu Province in October 1998, More than 100 papers have been received. Nearly 300 papers were received at the four sessions, including 51 papers at the seventh session in 1994, 58 papers at the eighth session in 1995 and 68 papers at the ninth session in 1996. In 1998, there were more than 100 articles in the tenth session. While the number of papers has increased year by year, the number of participants has increased from session to session. In 1994, there were more than 80 people in the seventh session, in 1995, in the eighth session, there were more than 80 people, in 1996, there were more than 100 people in the ninth session, and in 1998, there were more than 150 people in the tenth session. At the same time, the 47th Annual Meeting of the International Welding Society (IIW) was held in Beijing in 1994, and the academic conferences held by the welding Committee of the Chinese Institute of electronics in 1994 and 1995, the total number of papers submitted by the authors of brazing and diffusion welders in China reached 113. These statistics fully show that the research and application of brazing and diffusion welding technology in China are playing an increasingly important role in national economic construction

the research and application of brazing technology in foreign countries are also paid more and more attention by brazing workers. In particular, in recent years, more than 30 welding technical standards have been drafted and formulated by ISO, the International Electrotechnical Society and other international organizations, including as many as 25 standards related to brazing, nearly 10 officially issued in, and more than 10 are under revision and formulation. Especially in recent years, foreign brazing materials and brazing equipment have continuously entered the Chinese market. On the one hand, we have a deeper understanding of the latest research results of foreign brazing technology, and at the same time, it has promoted the research and development of brazing technology in China

1 brazing and diffusion welding technology of aluminum

brazing of aluminum and its alloys is one of the most studied and rapidly developed research fields in recent years. Because the heat dissipation components of various air conditioners and heaters are made of pure aluminum or aluminum alloy, and the application of various strengthened aluminum alloys in the national defense industry is growing at a very high rate of development. The premise for the application of these aluminum alloys is to solve the brazing problem first and have the supporting solder as the guarantee

the research and application of brazing technology for aluminum and its alloys in China are mainly aimed at aluminum radiators, aluminum stainless steel dissimilar materials, microwave devices, aluminum alloy door frames and other products

Harbin Welding Institute has researched and developed a material for brazing A1 at about 500 ℃. At present, production tests are being carried out. Once the problem of mass production cost is solved, the market prospect will be very broad

Beijing University of Aeronautics and Astronautics and Peking University proposed a flux and filler metal suitable for brazing aluminum and dissimilar joints between aluminum and other metals, and developed a liquid organic flux, a solid flux and Sn Zn me solder. The construction period of the project is expected to be 10 months. Some of the flux solder Market equipment have excellent brazing activity, corrosion resistance and processability at 10~500 mm/min, It has reached or exceeded the level of some of the best manufacturers in the world, and has been applied in the brazing of some radiators and refrigerator cold chambers. However, it has not yet formed industrialization or commercialization, and needs further research and development

in terms of A1 mg welding scooter, the year 2000 was a great exhibition. In Zhejiang and Guangdong, the consumption reached about 2000 tons. Only the welding wire manufacturers made huge profits

2 development and current situation of brazing materials since the reform and opening up, with the high-speed development of China's home appliance industry (especially the refrigeration industry, including refrigeration equipment, such as refrigerators, air conditioners and their three-way and four-way valves), automobile industry and electronic industry, brazing technology has been applied more and more widely, especially the annual sales volume of air conditioners in China reached 5million units in 1997 and 6.5 million units in 1998, It is expected to reach 8million sets in 1999. In recent years, wuyongning research group of Institute of nutrition and food safety of China Center for Disease Control and prevention has found that more than 12million sets of breast milk samples were tested in 12 provinces, making the output of brazing materials increase by 20% ~ 30% every year. It is estimated that the annual output of air conditioners in China will reach 15million ~ 20million sets in the next few years, Galanz recently announced that it had invested heavily in the field of air conditioning production. Therefore, the output of brazing materials will increase significantly in the application of air conditioners. It also summarized the long trend of the use of carbon fiber composites in automobiles, aircraft and other fields. The difference between the production of brazing materials and electrodes is that the technical key of electrodes mainly lies in the formula, the key of solder production lies in the production process, and the key of flux production lies in the formula and production process

2.1 the research and development institutions of brazing materials are increasing, and the manufacturers are increasing year by year

2.2 the number of research papers has increased year by year, and the level of papers has improved

2.3 the variety of solder increases, and the annual output of solder increases year by year

2.4 progress has been made in the standardization of brazing materials

2.5 significant progress has been made in the research and production of brazing materials (great progress has been made in the research and development of silver free and low silver solder; great progress has been made in the research and application of low tin solder and lead-free solder; new breakthroughs have been made in the processing and forming technology of solder.)

great progress has been made in solder forming technology in recent years. It mainly includes the following aspects:

(1) the new breakthrough of "amorphous" technology

the high alloying of solder makes some solder unable to be processed into wire or strip by conventional methods, which limits the application range of these solder. In the mid-1970s, the "amorphous" technology has moved from laboratory to industrial application in industrial developed countries, opening up a new processing way for brazing filler metals that cannot be processed by conventional methods. China just started research in the mid-1970s. From 1978, when the first national seminar on amorphous materials was held, to the mid-1980s, it took about 7 years for China to apply amorphous solder to production. In recent years, there has been a breakthrough in the winding technology. It has the capacity of medium and small batch production, and can produce 100mm wide and 0.03 ~ 0.05mm thick foil strips. At present, there are more than 30 varieties of brittle solders in five categories, including Ni based, Cu based, Cu-P, A1 based and Sn Pb, which can be produced by "amorphous" technology. Harbin Welding Research Institute has successfully made ag-cu-a1 medium temperature aluminum solder into 0.1 ~ 0.2 × 20mm thin strip, used for brazing aluminum and aluminum with PTC ceramics

(2) successful development of tape bonding filler metal. This technology has been successfully developed in China. By selecting new adhesives and improving the manufacturing process, the adhesion and warranty period have been improved. It is especially suitable for large-area brazing of Ni based high-temperature solder

(3) breakthrough progress has been made in the processing and forming technology of Cu-P series brazing filler metals

cu-p series brazing filler metals have good brazing process performance, but they are very brittle at room temperature. They have been used as cast rods for a long time, which brings a lot of inconvenience to the brazing work. After years of research, it can be drawn into ф 0.5 wire. At present, this processing technology is gradually mature. Many solder manufacturers can produce Cu-P series solder wires. The breakthrough of this processing technology widens the market for the application of Cu-P series solder

(4) many achievements have been made in the research and production of paste solder

soft solder paste for SMT technology and paste solder for brazing have been successfully developed by many units in recent years, and a small number of products have been put on the market. The market prospect of this field will also be very broad, because no matter the mobile, computer or refrigeration parts industries that are widely used, paste solder is widely used, and a large number of them are imported from abroad at present

3 development of brazing process and equipment

(1) arc brazing; (2) Transient liquid phase brazing; (3) Infrared brazing; (4) Vacuum brazing; (5) DC resistance brazing

(6) diffusion brazing; (7) High frequency brazing; (8) Microelectronic brazing (laser soldering, reflow soldering and wave soldering); (9) Brazing automation

4 conclusion

with the rapid development of welding technology, brazing and diffusion welding technology has become one of the most widely used connection technologies. With the continuous development of home appliance industry, microelectronics industry and communication industry, the research of brazing and diffusion welding technology will enter a new development period, especially the development of brazing materials will face a new development opportunity. (end)

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