Refractory Fiber Products Spraying Technology
Refractory fiber can also be called ceramic fiber, it is a kind of fibrous insulation fire resistant, corrosion resistant material.Developed in 1941, it can be used for paper, wire, rope, belt and other articles.
Refractory fibers are divided into amorphous (glassy) and polycrystalline (crystalline) types.Amorphous refractory fiber, including aluminum silicate, high purity silicate, aluminous silicate and high alumina refractory fiber.Polycrystalline refractory fiber, including mullite fiber, alumina fiber and zirconia fiber.(table 1) also has the highest allowable temperature classification according to the refractory fiber.
Refractory fiber is also a good infrared radiation material with good thermal power and infrared heating effect. The use of refractory fiber products can effectively save energy and is an ideal energy-saving and synergistic material.Production practice has proved that the application of continuous heating furnace refractory fiber can be energy saving more than 15%, can be used in intermittent industrial heating furnace energy saving more than 30%, at the same time can increase productivity and improve product quality, achieve light-duty furnace body structure, large-scale, comprehensive performance is good.
Refractory fibre soft, good elasticity, or the ideal sealing material, because of the insulation, sound attenuation, oxidation resistance, oil resistance and water resistance, construction is convenient, so in metallurgy, building materials, petroleum, chemical, shipbuilding, electric power, aerospace and other fields are widely used.
Polycrystalline refractory fiber is in the early 1970 s after amorphous refractory fiber developed a new type of high temperature heat insulation material, mainly used in working temperature higher than 1400 ℃ high temperature furnace, energy saving 25% ~ 40%.Multi-crystal refractory fiber can also be used as a composite reinforcing material and catalyst carrier.Multi-crystal refractory fibers can also be applied to the aerospace missile and atomic energy field.International has industrial production and application of polycrystalline refractory fiber are polycrystalline alumina fiber (Al2O380 % ~ 90%, SiO221 % ~ 20%), the polycrystalline mullite fibre (Al2O372 % ~ 79%, SiO221 % ~ 28%) and polycrystalline zirconia fibers (Y2O38 ZrO292 %, %), etc.
Energy problems have caused wide public concern all over the world. On the one hand, energy consumption is increasing year by year.
On the other hand, energy utilization rate is still very low, in our country this contradiction appears particularly outstanding.Furnaces in our country in terms of energy efficiency is only 50% ~ 60% in developed countries, the research and development of energy-saving materials has become the urgent task facing materials, refractory fiber because of its excellent thermal insulating properties as the development of energy-saving materials.
The research and development of foreign multi-crystal refractory fiber has been developed earlier, the production technology has matured, the technology is stable, and the comprehensive performance of fiber products has been applied in many fields.
As the main variety of multi-crystal refractory fiber, polycrystalline alumina fiber has excellent cost performance and great commercial value.Since the 1970s, many developed countries have invested a lot of energy in the development of polycrystalline alumina fiber.In the case of Britain's ICI company, the company has a history of more than 20 years to produce polycrystalline alumina fiber, the production of polycrystalline fiber using temperature is 1600 ℃.Foreign polycrystalline refractory fiber is not only used as high temperature insulation material, but also used as an enhanced material for advanced ceramics, metals and plastics.
Domestic polycrystalline refractory fiber mainly polycrystalline mullite fiber and polycrystalline alumina fiber is given priority to, in the late 1970 s, the luoyang refractory materials research institute and Shanghai second refractory plant started the development of polycrystalline mullite fiber.At present, the production of polymorite in China is made of aluminum chloride aqueous solution and metal aluminum powder.It is mainly used for using temperature is 1350 ℃ ~ 1400 ℃ ceramic veneers.By the luoyang refractory materials research institute of the development and production of polycrystalline alumina fiber (Al2O380 % ~ 95%) is mainly used in 1500 ℃ ~ 1650 ℃ high temperature furnace, the annual output of 80 tons.
The production of polycrystalline alumina fiber in China mainly adopts colloidal process, which is made into a solution of aluminum salt.
It is made into a spinning colloid, and then under certain conditions, it is made of fiber and heat treatment to obtain polycrystalline alumina fiber.Compared with foreign countries, the domestic polycrystalline refractory fiber still has a certain gap in technical level and product quality, and the production process and equipment are relatively backward.
Polycrystalline refractory fiber is a new high grade insulation material with great potential for development.The future development direction is to develop a series of high temperature and better use performance, which can meet various special requirements of polycrystalline refractory fiber related products.With polycrystalline refractory fiber as raw material to produce fiber castable, plastic and coating instead of refractory brick and not stereotypes refractories and other traditional refractories, can give full play to the polycrystalline refractory fiber material in the excellent properties of energy-saving, environmental protection, etc, and expand the use of the polycrystalline refractory fiber.
Fire resistant fiber with high temperature (1000 ~ 1400 ℃), resistant to vibration, heat, sound absorption and the advantages of light weight, has replaced brick structure and become refractory castable, heat preservation, heat insulation, sound insulation, fireproof material, in metallurgy, petroleum, chemical, machinery, building and other industries widely used.The construction technology of traditional refractory fiber mainly refers to the construction technology of refractory fiber products.It is difficult to construct the construction, the construction is difficult and the speed is slow, the quality control is difficult, the seam is much, the whole body is poor, the control worker labor intensity is big, the environment is bad.Fireproof fiber spraying technology is a new technology of fiber construction mechanization.The technology is to use the fiber spray gun, which is sprayed evenly through the diaphragm pump through the diaphragm pump, and the two are sprayed directly onto the work surface to form a three-dimensional network shape product structure.Overcoming the disadvantages of traditional construction technology is beneficial to the thermal efficiency of the advanced industrial furnaces.
Insulation refractory products made of refractory fiber as main raw materials are called refractory fiber products.Refractory fiber into amorphous (glass) and polycrystalline mass (amorphous) two broad categories: amorphous including silicate aluminum refractory fiber, high purity aluminum, chromium, aluminum silicate and high aluminum silicate refractory fibre;Polycrystalline refractory fiber includes mullite fiber, alumina fiber and zirconia fiber.Refractory fiber products of the highest use temperature for their products varieties of fiber, furnace atmosphere is different, generally in (1100 ~ 1500 ℃).
The combination of high temperature refractory materials has various properties.According to the chemical properties of the binding agent, it is divided into inorganic binding agent and organic binding agent.The inorganic binder mainly includes silicate, aluminate, phosphate, sulfate, chloride and sol.Organic binding agents include natural organics and organic compounds.The high temperature binding agent applied to refractory fiber spraying technology is sodium silicate.
Rock wool has good performance on heat preservation, heat insulation, low price, working temperature between (268 ~ 268 ℃).Can be used for the continuous working temperature below 600 ℃ furnaces and thermal insulation pipe lining.
The thermal conductivity of aluminum silicate was the lowest in the (250 ~ 300) kg/m3 conditions.Standard ordinary aluminum silicate fiber, alumina fiber coating is used to working temperature at 1000 ℃, 1200 ℃ respectively under thermal technology equipment, fire-resistant, heat insulation, thermal insulation layer, high aluminum with wrong composite fiber and contain wrong fiber coating applied to about 1300 ℃ high temperature furnaces.
The commonly used aluminum silicate series is a combination of heat and hardness.In the promise of working temperature range, ratio of binder composition, should help to form a binding chain network structure, and both need rapid coagulation, contraction after curing, and with a uniform, dispersion, mobility, the initial degree of reinforcement and the thermal state of sintering performance.Hot hard binder of refractoriness is not lower than 1750 ℃, the viscosity (6.0 ~ 8.0) x 10-3 pa s..