[Zhongbo.com] Vacuum glass, a popular glass deep-processing product, due to its professional field and work nature, has unwittingly gone through 8 years in this "vacuum glass" industry, and it is quite involved. deep. In retrospect, all of this has been smoothly completed: during the period of schooling, we have been accumulating knowledge about the preparation and characterization of silicate materials, especially glass. After work, we continue to work on related glass materials and processing applications, which is inadvertent. The products involved in low-temperature sealing glass, energy-saving glass, etc., such materials have many important applications in electronic sealing and aerospace, but the gap between China and abroad is huge. It is the vacuum glass demand for low-temperature sealing glass. It is driven by low-temperature, lead-free and process optimization. Starting from sealing glass materials, further study and explore glass sealing technology, and gradually expand to glass sealing technology and equipment. ,product testing……. I believe that I am eager to learn. In just a few years, I have accumulated 30 years of knowledge, experience, and experience in the vacuum glass industry. I have studied it carefully, and even repeated it. Now it seems that there is a lot of work. extra. Perhaps thanks to the long-term research habits, I always try hard to make every detail and link clear. I really want to thank the predecessors of vacuum glass for their selfless support and the advantages of the building materials platform. As a science and technology worker, he has published some of his research conclusions or ideas in the form of scientific reports such as papers and patents. The scientific papers are rigorous, and the data, charts, analysis, and conclusions are relatively objective. But the analysis of industry technology is different, especially the future technology trend or market expectations are very complicated, too many cross-factors. However, based on a wide range of facts and technical status, rational knowledge of industry forecasts and technology upgrades is also expected. In 2018, I was fortunate to participate in the compilation and publication of the book "Vacuum Glass" edited by Professor Tang Jianzheng. At the same time, the first vacuum glass technology seminar was held. I think these events should be regarded as the nodes for the development of vacuum glass. The situation of China's vacuum glass industry Presenting new features, "difficult steps", "hundred flowers", "going forward" and "post-waves pushing forward waves" do not know whether it is appropriate, I believe that people in the industry will have a deep understanding. As a glass product with better energy-saving effect, vacuum glass has obvious performance and application advantages, which attracts more and more enterprises to participate in the research and development and industrialization of vacuum glass. Compared with tempered, hollow and other glass deep processing products, it can also be counted as high value-added products. After more than 20 years of research and development in China, vacuum glass has gradually developed a stable batch preparation and application, and has been verified by product performance and life. Throughout the 20 years of vacuum glass progress, the following work processes have been completed in China: (1) expansion from vacuum glass theory and laboratory preparation to industrial production, and application of many cases; (2) creation of tempered vacuum glass in China The upgraded product of laminated vacuum glass effectively improves the safety of vacuum glass; (3) Explore and implement the metallization sealing process of vacuum glass, and China's vacuum glass continues to lead the world. Despite this, vacuum glass has not yet entered the real stage of large-scale production and application due to its capacity, cost and inherent shortcomings. Materials are the basis of all industrial production, low temperature sealing solder, metal brazing, support materials and even high quality original glass and coated glass involved in vacuum glass, especially the choice of sealing materials also determines the sealing The route of the process, under the determined route, can develop and select effective equipment and production line configuration. Under the conditions of production technology and equipment, the rest is process control and product quality assurance. Therefore, a seemingly simple piece of vacuum glass involves a lot of materials, thermal, mechanical, and testing aspects. Because of the many vacuum glass processes, the previous process has a close correlation and influence on the subsequent processes and product quality. Therefore, process detail control in vacuum glass production is critical to quality. The direct benefit brought by the improvement of process detail control is the improvement of the yield, and the comprehensive yield can be controlled above 90%, which also becomes a prerequisite for cost reduction. When it comes to the cost of vacuum glass, especially in the large-scale application of building energy conservation, the price has become a hurdle, 500 yuan, 400 yuan ... or even lower terminal price to meet the market demand, from theoretical cost accounting Look, this is achievable. Talk about so much around vacuum glass, or return to the rational level, talk about several problems often encountered in vacuum glass manufacturing and marketing. (1) Debate between tempering and non-tempering This is also a discussion of the safety of vacuum glass. Within the scope of China's regional glass deep processing products, tempered glass is often equated with safety glass. Safety issues are always a big problem. Building glass safety is equally important. It is undeniable that the stress concentration of vacuum glass support points is an inevitable disadvantage of the vacuum glass structure itself. This is also the impact of falling ball, pendulum test, and dispersion. The main reason for the mechanical properties of elastic impact can not be compared with the existing single-piece tempered, tempered hollow, laminated glass products. Therefore, there has been disagreement on the scientific and rational use of vacuum glass. One is to hesitate to use vacuum glass safely, and the other is to over-emphasize the safety of vacuum glass in the voice of vacuum glass manufacturers. I think this is all It is not a comprehensive and objective understanding of vacuum glass. The "Technical Regulations for the Application of Architectural Glass" clearly stipulates the safety of glass, that is, it is installed on architectural glass that is susceptible to collisions with human bodies or objects, such as floor-to-ceiling windows, glass doors, glass partitions, etc., in addition to safety glass. Protective measures, such as warnings, guardrails, etc. If you want to define the safety glass, I think that "safe glass is a kind of glass that is violently vibrated or impacted and not broken, even broken and not easy to hurt the glass" is a general summary. Therefore, in addition to improving the performance of vacuum glass, it is necessary to improve and optimize the use of vacuum glass. It should exert its advantages of energy saving and sound insulation within the scope allowed by relevant regulations. As a vacuum glass practitioner, it is still necessary to affirm the performance advantages of "tempered vacuum glass". The vacuum glass is prepared by using the tempered glass original sheet. If the original sheet glass can maintain a large surface compressive stress after the preparation, that is, maintaining the physical tempering characteristics, we can call it "tempered vacuum glass" for the time being. Since the strength and impact resistance of the physical tempered glass is greatly improved compared with the ordinary original sheet, the tempered vacuum glass also greatly improves the overall impact strength, wind pressure resistance, bending resistance and thermal shock resistance of the vacuum glass. At the same time, it has broken safety. In addition, in the mechanical design of the vacuum glass, the support spacing can also be appropriately increased to optimize the thermal insulation performance and visual effect of the vacuum glass. Therefore, even if there is controversy about “tempered vacuum glassâ€, there are still some flaws. In the case of technical and production conditions, it is still the direction that future products should adhere to. (2) Misunderstanding of performance and quality Vacuum glass is characterized by thermal and thermal insulation, so the performance indicators that are often of interest are the central thermal conductivity value (in this case, U value) and the weighted sound insulation. It is well known that the excellent thermal and acoustic insulation properties of vacuum glass benefit from the slit vacuum between the two glass sheets. The higher vacuum state effectively reduces the medium for heat transfer and sound transmission, which is easy to understand. According to the composition of the vacuum glass thermal conductivity, the research results show that the thermal conductivity of the residual gas decreases to a critical level when the vacuum in the vacuum chamber reaches 10-1 Pa, and the gas thermal conductivity dominates when the vacuum exceeds 10 Pa. Factor, vacuum glass loses its meaning. Therefore, we can use 10-2Pa as a standard vacuum for vacuum glass performance, and 10Pa as a critical vacuum for vacuum glass to completely fail. (Note: Of course, in actual production, in order to obtain a vacuum of 10-2Pa in the slit vacuum, the requirements for the vacuum pump, vacuum line or vacuum kettle body are still very high, and the vacuum of 10-4Pa production needs to be guaranteed.) Under the premise of a certain degree of vacuum, the heat transfer and absorption of vacuum glass mainly depends on the type of Low-E glass and the material and placement of the support. According to our experience, the vacuum glass made of ordinary white glass has a U value of 2.0Wm-2K-1 or more. When Low-E glass is used, especially after high performance off-line single silver and double silver Low-E glass. The U value of the vacuum glass can be easily reduced to less than 1.0Wm-2K-1, and can even be reduced to 0.5Wm-2K-1 through optimized structural design. What I want to point out here is that, according to the performance index of the existing large-scale ordinary Low-E glass in China, the vacuum glass U value prepared by using single silver product is between 0.6~0.8Wm-2K-1, which is a normal and credible level. And this level of products has basically met the needs of most high-end energy-efficient building doors and windows in China. Recently, I have seen many reports and promotional materials for vacuum glass. More or less, the heat transfer coefficient of vacuum glass has been over-emphasized. Many U-values ​​of glass samples have achieved 0.5Wm-2K-1 or lower. Of course it is very good. However, from the existing vacuum glass industrialization and application experience, vacuum glass quality control, vacuum life, mechanical life and other issues should be worthy of attention. The quality of vacuum glass has been discussed. The quality indicators should include thermal performance, mechanical properties, appearance, life and product performance, quality consistency and stability, which is difficult to achieve in production. These problems are actually related to all aspects of vacuum glass production, raw material selection, process steps, equipment accuracy, inspection procedures, etc. It is also very complicated to think about, and we have to do a lot of work. For example, 1) peripheral sealing materials, whether traditional low-temperature glass sealing or innovative metal sealing, the strength of the sealing material itself, gas permeability, interface structure, etc. are to meet the requirements of vacuum glass; 2) support The material, microstructure, and layout of the material must meet the requirements of the vacuum glass mechanics and the glass's own load-resistance ability, especially not blindly increasing the support spacing, and not adding more risks to the inherent stress concentration disadvantages; 3) No matter what The sealing method or the non-sealing method reduces the loss of vacuum when the sealing state is closed. To ensure the effective vacuum in the vacuum chamber and the gas release amount in the late glass surface, the process specification of the vacuum glass must be strictly followed; 4) Strict Factory inspection and installation inspection, according to the current level, should be 100% full coverage qualitative inspection of vacuum glass factory and more than 5% U value sampling, of course, in the installation process will also cause glass failure and damage, at the project site The inspection is also essential. Having said that, what I want to express here is that the performance index does not mean the quality is good or bad, and the sample is not representative of the stability of the product. The future development of vacuum glass should not blindly pursue low U value, too high degree of tempering (surface stress), I believe that product quality and product life are king, vacuum glass itself should pay attention to this problem. (3) One-step method and two-step method (route dispute) Speaking of the dispute of the route or the structure dispute, it is very easy for people who understand the manufacture of vacuum glass to understand it. In fact, the material or process route is different. The structure and performance of the vacuum glass itself are similar. It has been said that the basic materials are the cornerstone of China's industrial technological progress. For vacuum glass, the choice of edge-sealing materials is especially critical. Different materials may correspond to different processes and different equipment and production processes are required. The "step" here mainly refers to the edge sealing process and the vacuum sealing process. If it is sequentially sealed, evacuated, and sealed in two devices, this is the usual two-step method, a typical one-step method. The representative process is that the pre-spliced ​​glass is edge-sealed in the vacuum chamber to simultaneously obtain an internal high vacuum state. Therefore, the single furnace used in the early stage of vacuum glass (enclosed air-sealing integrated furnace) and the later improved continuous production line (such as roller-type, tunnel-type kiln sealing directly into the vacuum chamber vacuum exhaust, sealing) The vacuum glass production in the same equipment and production line has also experienced three steps of high temperature sealing, medium temperature vacuuming and sealing, which can be regarded as the improvement and optimization of the two-step method. From another point of view, the one-step and two-step method in the appearance of vacuum glass may be the difference between the presence and absence of the suction port. The two-step method exists regardless of the position, structure and form of the suction port, and one step The vacuum glass without the suction port is slightly better in appearance. From the results, there is no essential difference between the one-step method and the two-step method, but I think there are still advantages and disadvantages. Judging from the simple one-step experiment, there are currently several problems that cannot be avoided: 1) The problem of the pores of the existing low-temperature glass sealing materials welded under vacuum environment, the vacuum softening and melting of the glass under vacuum will definitely cause the volatilization of the gas, more or less, which will cause the porosity of the edge sealing tape. Improve, even affect the air tightness and bonding strength, perhaps the metal sealing material performs much better under vacuum, but its wettability and interfacial properties are also different from the atmospheric atmosphere; 2) From the literature data of more vacuum glass, the desorption and exhaust of the glass surface is mainly based on heating, and the better baking temperature is about 300 °C. Therefore, when the process is feasible, the appropriate low temperature should be selected. Metal brazing material; 3) Many operations under vacuum are different from normal pressure. Poor visibility is likely to cause vacuum glass transmission and pressure counterweight errors, especially the lack of necessary heat convection and heat conduction during heating under vacuum, sealing the edges. The difficulty of heating efficiency, heating uniformity, and consistency. Of course, with the advancement of automation, control technology and vacuum technology, these problems will be gradually solved. In the previous glass cold working and vacuum glass preparation process, the one-step and two-step methods are the same, and even one-step method requires more pre-treatment work. In turn, the two-step method has many and many optimized modifications, such as single furnace, multi-body furnace, continuous line, automatic line, etc., tube seal, side seal, flat seal, etc., in comparison with the one-step method, if adopted The completely separate edge sealing and air extraction device involves the process of twice lifting and lowering the temperature of the glass, resulting in a slightly better energy consumption and lower efficiency. In addition, the vacuum pump line is used to evacuate the vacuum through the exhaust hood or the vent hole. The effect of molecular diffusion under slit vacuum requires a long time to obtain a qualified vacuum, which is also a key issue that restricts the production efficiency of vacuum glass. As mentioned above, with the advancement of various technologies and the modification of process equipment, the two-step method will become more and more mature. When batch and continuousization are realized, the efficiency and cost problems will be solved. There is no essential difference between one step and two steps. At least at present, there should be no good or bad, but each needs improvement. It needs to be confirmed by practice. For enterprises or investors, choose their own technology sources, analyze their own technological advantages, evaluate the future investment scale, and clearly locate the product direction, step by step. (4) Development stage and bottlenecks I remember that at the vacuum glass seminar, some experts put forward the industry life cycle theory of glass products. I was very interested and deliberately went to understand it. The industry life cycle theory is developed on the basis of product life cycle theory. A research field in the economic sense is greatly concerned by economics and management researchers. The typical representative is the industry life cycle curve. The industry life cycle is divided by indicators such as market growth rate, demand growth potential, product variety, competitors, market share, barriers to entry, technological innovation, and user buying behavior. Stage. From this standard, vacuum glass is really young. I personally think that it is still in the transition period of the initial period and the growth period (see the typical characteristics and judgments of different stages). In the initial stage, the company always tries to attract customers' attention to its products. When the industry enters the growth stage, potential competitors are attracted and enter the product market, and market competition is intensified. Vacuum glass has been developed in China for more than 20 years. The basic theory, basic technology, product structure and application fields are basically mature. However, only a small number of companies are currently operating this emerging industry, and at the same time, higher product costs and Prices and smaller market demands also expose these startups to significant investment risks. In addition, in the initial stage, companies may also be in danger of bankruptcy due to financial difficulties. Therefore, such enterprises are more suitable for speculators than investors. During this period, the market growth rate was relatively high, demand growth was rapid, and technology changes were large. Users in various industries in the industry were mainly committed to opening up new users and occupying the market. However, there was a great technical uncertainty at this time. There is a lot of room for product, market, service and other strategies. There is not much information on industry characteristics, industry competition status, user characteristics, etc., and enterprises have low entry barriers. In the later stage of the start-up phase, with the improvement of production technology, the reduction of production costs and the expansion of market demand, the new industry will gradually shift from the high-risk and low-yield start-up period to the high-risk and high-yield growth period. The industrial life cycle plays an important role in corporate decision-making and government industrial policies. Only when a company defines the life cycle stage of the industry and the position of the industry value of the enterprise can a clear strategic positioning of the enterprise be made. For government decision-making, only by understanding the industrial life cycle, can we understand the law of industrial development, conduct industrial planning for each stage of the life cycle, and formulate industrial policies. Whether or not we can grasp the law of industrial life cycle is the key to the stable and rapid development of a country's economy. Of course, it is also the key to whether a company can grow and develop. In an industry, the development factors of an industry and a product are complex. Personally, the vacuum glass currently faces its own problems more than the external ones. These are the bottlenecks that restrict the development of vacuum glass. 1) From the perspective of technical process, several technical routes need to be shaped as soon as possible to improve maturity; the supporting equipment production line is also able to form a universal standardized production line while improving production efficiency, which will be the popularization of vacuum glass in the future. Key points (can you achieve the maturity of the current hollow line in the future?). 2) From the perspective of market application, the cost price is a hurdle. This requires the vacuum glass enterprise's own technological progress and management management improvement, and develops vacuum glass products that are suitable for ordinary buildings, energy-saving buildings, photovoltaic and home appliance industries, and realize cost and profit. A stable and stable business model. 3) According to the whole industry, vacuum glass is too small and too weak. Whether in technology or in market competition, enterprises should open up cooperation and seek common development, active, open and standardized exchange and cooperation, as well as industry, university and research and development. They are all breakthroughs that change the current stalemate. 4) For the appeal of the external environment and national policies, the big feeling here is the standardization problem in the field of building doors and windows in China. Once I received a 64-piece glass order, there are 22 sizes. It is really a joke. If it is always such a market demand, vacuum glass is really a disaster. (5) perception and vision A person's strength is meager, and the more he talks, it seems that he has no confidence. But after so many years, his feelings about vacuum glass are deep, and it is not easy to give up. Only by learning more and exploring more can he be more determined in chaos. 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