It has the characteristics of general fibers, such as softness, elasticity, and certain tensile strength. It can be further processed into various products such as paper, thread, rope, belt, blanket, and felt; and It has high temperature resistance and corrosion resistance properties that ordinary fibers do not have. As a refractory and heat-insulating material, it has been widely used in metallurgy, chemical industry, machinery, building materials, shipbuilding, aviation, aerospace and other industrial sectors. In 1941, the Central Research Institute of Babcock & Wilcox Co. in the United States discovered that by blowing the stream of kaolin melt with compressed air, a fiber similar in shape to asbestos was obtained. Later, in 1954, the patent for the production equipment and process of this fiber was announced and officially put into production. In the early 1960s, the United States developed the production process of refractory fiber products and spread the technology to Japan and Europe. In the mid-1960s, various countries began to use refractory fiber blankets and refractory fiber wet felts instead of refractory bricks as industrial furnace linings, and successively developed new varieties such as high-purity aluminum silicate fibers and high-aluminum refractory fibers. In the 1970s, polycrystalline fiber was successfully developed and developed rapidly. In 1974, the British Imperial Chemical Industries Ltd first built a semi-industrial experimental device for the production of polycrystalline alumina fiber. In 1979, it was completed with an annual output of 500-700t. . industrial production line. In the 1980s, Japan developed mullite fiber containing 80% Al2O3, and the United States also produced mullite fiber containing 72% Al2O3. The scope of use has expanded from heat treatment furnaces to high-temperature fields such as heating furnaces.
China began to trial-produce aluminum silicate refractory fibers in the early 1970s and successfully used them in industrial furnaces. In the 1980s, great progress was made in basic fiber theory, new product development, and promotion and application. Three types of polycrystalline refractory fibers have been successfully developed: Al2O3 72%, Al2O3 80%, and Al2O3 95%. ZrO2 polycrystalline fiber was also successfully developed in the laboratory. Refractory fibers are divided into two categories: amorphous (glassy state) and polycrystalline (crystalline state). Amorphous refractory fibers include aluminum silicate, high-purity aluminum silicate, chromium-containing aluminum silicate and high-aluminum refractory fibers. Polycrystalline refractory fibers include mullite fiber, alumina fiber and zirconia fiber. (Table 1) There are also classifications based on the maximum allowable use temperature of refractory fibers.
Characteristics
Refractory fiber is also a good infrared radiation material, with good thermal capacity and infrared heating effect. The use of refractory fiber products can effectively save energy and is an ideal energy-saving and efficiency-enhancing material. . Production practice has proven that applying refractory fiber to continuous heating industrial furnaces can save more than 15% of energy, and using refractory fibers in intermittent industrial heating furnaces can save more than 30% of energy. At the same time, it can increase productivity and product quality, and achieve lighter and larger furnace structures. , good overall performance.
Refractory fiber is soft and elastic, and is an ideal sealing material. Due to its insulation, silencer, antioxidant, oil and water resistance properties, and easy construction, it is widely used in metallurgy, building materials, petroleum, chemical industry, shipbuilding, and electric power. , aerospace and other fields are widely used.
Polycrystalline refractory fiber is a new type of high-temperature insulation material developed in the early 1970s after amorphous refractory fiber. It is mainly used in high-temperature kilns with operating temperatures above 1400°C and can save 25% of energy. %~40%. Polycrystalline refractory fibers can also be used as composite reinforcement materials and catalyst carriers, with good application effects. Polycrystalline refractory fibers can also be used in aerospace missiles and atomic energy fields. The polycrystalline refractory fibers that have been industrially produced and applied internationally mainly include polycrystalline alumina fiber (Al2O3 80% ~ 90%, SiO2 21% ~ 20%), polycrystalline mullite fiber (Al2O3 72% ~ 79%, SiO2 21% ~ 28 %) and polycrystalline zirconia fiber (ZrO292%, Y2O38%), etc.
Energy issues have attracted widespread attention from all over the world. On the one hand, energy consumption is increasing year by year.
On the other hand, energy utilization is still very low. This contradiction is particularly evident in our country. protrude. The energy utilization rate of thermal kilns in my country is only 50% to 60% of that in developed countries. The research and development of energy-saving materials has become an urgent task facing the material field. Refractory fiber has become an energy-saving material due to its excellent thermal insulation properties. development hot spots.
The research and development of foreign polycrystalline refractory fibers started early, the production technology has become mature, the process is stable, and the comprehensive performance of fiber products is superior, and it has been applied in many fields.
As the main variety of polycrystalline refractory fiber, polycrystalline alumina fiber has excellent cost performance and huge commercial value. Since the 1970s, many developed countries have invested a lot of energy in the research and development of polycrystalline alumina fibers. Take the British company ICI as an example. The company has a history of producing polycrystalline alumina fibers for more than 20 years. The polycrystalline fibers produced can be used at temperatures up to 1,600°C. Foreign polycrystalline refractory fibers are not only used as high-temperature insulation materials, but also as reinforcing materials for advanced ceramics, metals and plastics.
Domestic polycrystalline refractory fibers are mainly polycrystalline mullite fibers and polycrystalline alumina fibers. In the late 1970s, Luoyang Refractory Materials Research Institute and Shanghai Second Refractory Materials Factory began to produce polycrystalline refractory fibers. Development of mullite fibers. At present, the domestic production of multi-grade mullite mostly uses aluminum chloride aqueous solution and metal aluminum powder as raw materials, and is produced by the colloid method. Mainly used for ceramic veneers with operating temperatures of 1350°C to 1400°C. Polycrystalline alumina fiber (Al2O3 80%~95%) developed and produced by Luoyang Refractory Materials Research Institute is mainly used in high-temperature kilns of 1500℃~1650℃, with an annual output of 80 tons.
my country's manufacturing of polycrystalline alumina fibers mainly uses the colloid process. The aluminum salt is made into a solution, heated and shrunk.
It is made into a spinning colloid, and then fiber is formed under specific conditions. and heat treatment to obtain polycrystalline alumina fibers. Compared with foreign countries, there is still a certain gap in the technical level and product quality of domestic polycrystalline refractory fibers, and the production technology and equipment are also relatively backward.
Polycrystalline refractory fiber is a high-grade new thermal insulation material with great development potential. The future development direction is to develop a series of polycrystalline refractory fiber-related products with higher operating temperatures and better performance that can meet various special requirements. Polycrystalline refractory fiber is used as raw material to produce fiber castables, plastics and coatings to replace traditional refractory materials such as refractory bricks and unshaped refractory materials. It can give full play to the excellent performance of polycrystalline refractory fiber materials in terms of energy saving and environmental protection, and expand Application scope of polycrystalline refractory fiber.