Recently, BTXT Rare Earth Materials Research Institute released its newest product: thermal insulation rare earth glass coating
"The heat-insulating rare earth glass coating can be directly applied to the glass surface, and it can quickly cool down within 3 hours, and the maximum temperature can be adjusted to 7-15 degrees, which can save energy by 25%-40%." said Dr. Yin Jian from Tianjin Branch of BTXT Rare Earth Research Institute.
Rare earth coating is the preparation and performance screening of ternary rare earth co-doped boride materials by BTXT Rare Earth Research Institute to prepare stable and high performance rare earth nano composite thermal insulation coating products.
"We have successfully developed more than ten kinds of rare earth nano thermal insulation slurry industrial preparation technologies. At present, the technology has published 2 domestic papers, applied for 3 domestic invention patents, and 1 appearance design patent." Lu, senior engineer of BTXT Rare Earth Research Institute Fei said that the coating is ahead of similar products such as glass film, low-E glass and insulating glass in the current market in terms of thermal insulation effect, convenience and stability.
Optimizing the insulation performance of glass is imperative
In the "13th Five-Year Plan for Building Energy Conservation and Green Building Development", it is proposed that by 2020, the energy efficiency of new buildings in China's cities and towns will increase by 20%, the proportion of green building area will exceed 50%, and 40% of building energy consumption will be consumed by glass doors and windows. Therefore, improving the thermal insulation performance of the glass is particularly critical.
As we all know, the heat energy on the earth's surface mainly comes from sunlight, and the spectrum of sunlight is mainly concentrated in the range of 200-2500nm, of which: the range of 200-400nm is ultraviolet, its energy accounts for about 5% of the total energy of sunlight, and the range of 400-720nm The inner part is visible light, whose energy accounts for about 45% of the total energy of sunlight, and the range of 720-2500nm is infrared, whose energy accounts for half of the total energy of sunlight.
Infrared rays are invisible to the human eye. Therefore, how to effectively block infrared rays and improve the heat insulation performance of glass without affecting the transmission of visible light is one of the most difficult points in domestic and foreign technology research and development. At present, the research and development of high-quality, high-permeability heat-insulating film is mainly concentrated in developed countries such as the United States and Japan. "Although there are many methods for blocking sunlight in the prior art, each has many problems." Lu Fei said.
Lu Fei explained the shortcomings of low-emissivity glass (Low-E), the most commonly used building insulation glass. This type of glass achieves the thermal insulation effect by coating the surface of ordinary glass. However, after extensive use of this type of glass on the exterior wall of the building, although it has good heat preservation and heat insulation properties for the building itself, it will reflect a lot of sunlight and cause a lot of light pollution problems.
People working in a light-polluted environment for a long time can cause loss of vision, dizziness, insomnia, heart palpitations, decreased appetite, and depression, which seriously affect people's physical and mental health. In addition, Low-E glass cannot obtain heat insulation on the surface of the glass through post-painting and other methods. In addition, due to the oxidation of the metal layer, the life of the surface layer is much lower than that of the glass itself, which makes Low-E glass unable to be It is used to upgrade the existing architectural glass.
In addition, colored glass absorbs visible light while absorbing heat. It will greatly sacrifice visible light transmittance while achieving heat insulation, and present obvious colors, which greatly limits its need for high visible light such as car front windshields. Through the application of the scene.
"At present, the most widely used infrared absorption material-cesium tungsten bronze material, has the best infrared absorption effect. However, it will exhibit photochromic phenomenon under ultraviolet radiation, and will interact with water and oxygen under heating conditions. An irreversible oxidation reaction occurs, generating tungsten trioxide and losing its infrared absorption properties." Yin Jian said.
A new thermal insulation coating comes out
From the above analysis, it can be seen that the thermal insulation principle of traditional Low-E glass and glass products is to achieve the thermal insulation effect by coating the surface of ordinary glass. After coating, Low-E glass can reflect far infrared rays with wavelengths above 2500nm. , But it can also cause pollution. Absorbing photons may be a better choice.
"We are also inspired by the phenomenon of localized surface plasmon resonance (LSPR), because the surface electrons of gold nanobelts with a certain aspect ratio can resonate with incident photons of a certain frequency, and strongly absorb the incident photons before passing through Adjusting the particle size and morphology of the material can achieve selective absorption of infrared photons, which can be made into infrared absorbing materials." Lu Fei said.
According to Lu Fei, the coating they made is based on rare earth compounds. On the one hand, because boron atoms have extremely strong electronegativity, they can form a strong force with rare earth elements, resulting in the final formation of rare earth nano thermal insulation materials. It has excellent acid and alkali resistance; on the other hand, in the formed rare earth nano boride material, the outer layer electrons of the rare earth element itself provide a large number of free electrons. When the photon of the incident light is excited, the free electron resonates with the incident photon , Which manifests as heat absorption capacity in the macroscopic view.
In addition, by adjusting the type and doping amount of rare earth elements, the wavelength range in which incident photons resonate can be further controlled. Using this method, the BTXT R&D team successfully developed a high-performance rare earth nanocomposite thermal insulation material with good weather resistance, which perfectly solved the problem of insufficient environmental stability of existing materials and the inability to absorb infrared spectra.
"The coating we developed has a red and ultraviolet barrier greater than 90%, a visible light transmittance greater than or equal to 70%, and its thermal insulation effect, convenience and stability are all ahead of the likes of glass film, Low-E glass and insulating glass. Products.” Wen Yongqing said. They have also done several experiments. Taking the comparison of the effects of LOW-E insulating glass and thermally insulating rare earth laminated glass as an example, under the same conditions, the double silver LOW-E insulating glass and thermally insulating rare earth The laminated glass is placed in front of the infrared lamp, the infrared heat value of double silver LOW-E insulating glass is 3417, the ultraviolet value of double silver LOW-E insulating glass is 4857, the blocking rate is 50%, and the infrared heat value of thermal insulation rare earth laminated glass It is 320, the ultraviolet value of the insulating rare earth laminated glass is 19.4, and the barrier rate is as high as 99.8%.
It can be seen that even the dual-silver LOW-E insulating glass with excellent performance on the market currently lags behind the single-layer RE laminated glass using heat-insulating rare earth technology in terms of heat insulation, sun protection and energy saving.
Coating application helps my country's green development
In November 2019, the Rare Earth Research Institute and CDYT Technology established a joint laboratory for thermal insulation rare earths to jointly promote the industrialization of new rare earth nano thermal insulation coatings. The preparation technology of new rare earth nano thermal insulation materials and coating industries has made breakthroughs.
"At present, we have built the first domestic pilot production demonstration line of rare earth nano thermal insulation slurry with a monthly output of 800 kg, which can save energy by 25%-40%." said Yang Jue, the general manager of CDYT Technology. The products are equivalent, or even better than foreign products. At the technical level, it has realized "curving overtaking", filling the gap of domestic insulation glass coating materials, and can completely replace imported products.
As we all know, solar thermal energy mainly exists through infrared radiation, and has the characteristics of high temperature to low temperature transfer.
Therefore, the outdoor high temperature in summer will rush indoors, causing the air conditioning load to increase, and red/ultraviolet rays can make the human skin feel hot; the coating can produce plasma resonance effect with light waves in the range of 200-400nm and 700-2500nm, radiating heat energy Can not penetrate the coating, it can achieve good heat insulation and sun protection performance. At the same time, because the radiant heat energy is blocked, the indoor temperature cannot rise rapidly and continuously, which reduces the air conditioning load, greatly saves air conditioning costs, and achieves energy saving. purpose.
In winter, the essence of indoor heat source heating is still infrared light, which is the internal vibration of particles propagating electromagnetic waves. Therefore, heating electromagnetic waves cannot effectively penetrate the heat-insulating rare earth coating (plasma resonance), and the heat source is left in large quantities. Indoors, the heating will heat up faster, the locking and heat preservation will be better, super energy saving.
The problem of building energy consumption is particularly severe in China. The total building area in our country is huge, and more than 90% of it uses ordinary glass. According to the calculation of China's energy-saving targets in 2010, an average of approximately 1.32 billion square meters of thermal insulation glass is added each year, and the market demand for rare earth nano thermal insulation materials is huge.
"After the product is launched, it can be widely used in energy-saving and environmentally-friendly automobiles and energy-saving architectural glass. It can effectively solve the problems of high internal temperature of automobiles and buildings and large energy consumption of air-conditioning.