In a broad sense, our understanding of glass fiber has always been that it is an inorganic non-metallic material, but with the deepening of research, we know that there are actually many types of glass fibers, and they have excellent performance, and there are many outstanding The advantages. For example, its mechanical strength is particularly high, and its heat resistance and corrosion resistance are also particularly good. It is true that no material is perfect, and glass fiber also has its own shortcomings that cannot be ignored, that is, it is not wear-resistant and prone to brittleness. Therefore, in practical application, we must make use of our strengths and avoid our weaknesses.
The raw materials of glass fiber are simple to obtain, mainly discarded old glass or glass products. The glass fiber is very fine, and more than 20 glass monofilaments together are equivalent to the thickness of a hair. Glass fiber can usually be used as a reinforcing material in composite materials. Due to the deepening of glass fiber research in recent years, it plays an increasingly important role in our production and life. This paper mainly studies the production process and application of glass fiber, and introduces the properties, main components, main characteristics, material classification, production process, safety protection, main use, safety protection, industry status, and development prospect of glass fiber.
Melting point: 680℃
Boiling point: 1000℃
Glass fiber also has an extremely superior feature, that is, its tensile strength is very large. The tensile strength is 6.3~6.9 g/d in the standard state and 5.4~5.8 g/d in the wet state. Such excellent properties make glass fiber often Can be used universally as reinforcing material. It has an A density of 2.54. Glass fiber is also very heat-resistant, and it retains its normal properties at 300°C. Fiberglass is also sometimes widely used as a thermal insulation and shielding material, thanks to its electrical insulating properties and its inability to corrode easily.
1.2 Main ingredients
The composition of glass fiber is relatively complex. Generally, the main components that are recognized by everyone are silica, magnesium oxide, sodium oxide, boron oxide, aluminum oxide, calcium oxide and so on. The diameter of the monofilament of glass fiber is about 10 microns, which is equivalent to 1/10 of the diameter of the hair. Each bundle of fibers is composed of thousands of monofilaments. The drawing process is slightly different. Usually, the content of silica in glass fiber accounts for 50% to 65%. The tensile strength of glass fibers with aluminum oxide content over 20% is relatively high, usually high-strength glass fibers, while the aluminum oxide content of alkali-free glass fibers is generally about 15%. If you want to make the glass fiber have a larger elastic modulus, you must ensure that the content of magnesium oxide is greater than 10%. Because of the glass fiber containing a small amount of ferric oxide, its corrosion resistance has been improved to varying degrees.
1.3 Main Features
1.3.1 Raw materials and applications Compared with inorganic fibers, glass fibers have superior performance. It is more difficult to ignite, heat-resistant, heat-insulating, more stable, and tensile-resistant. But it is brittle and has poor wear resistance. It is used to make reinforced plastics or to strengthen rubber. As a reinforcing material, glass fiber has the following characteristics: (1) Its tensile strength is better than other materials, but its elongation is very low. (2) The elastic coefficient is more suitable. (3) Within the elastic limit, the glass fiber can extend for a long time and is very tensile, so it can absorb a large amount of energy in the face of impact. (4) Since glass fiber is inorganic fiber, inorganic fiber has many advantages, it is not easy to burn and its chemical properties are relatively stable. (5) It is not easy to absorb water. (6) Heat-resistant and stable in nature, not easy to react. (7) Its processability is very good, and it can be processed into excellent products in various shapes such as strands, felts, bundles, and woven fabrics. (8) Can transmit light. (9) Because the materials are easy to obtain, the price is not expensive. (10) At high temperature, instead of burning, it melts into liquid beads.
1.4 Classification According to different classification standards, glass fibers can be divided into many kinds. According to different shapes and lengths, it can be divided into three types: continuous fibers, fiber cotton and fixed-length fibers. According to different components, such as the alkali content, it can be divided into three types: alkali-free glass fiber, medium-alkali glass fiber, and high-alkali glass fiber.
1.5 Production raw materials In actual industrial production, in order to produce glass fiber, we need alumina, quartz sand, limestone, pyrophyllite, dolomite, soda ash, mirabilite, boric acid, fluorite, ground glass fiber, etc.
1.6 Production methods Industrial production methods can be divided into two categories: one is to melt glass fibers first, and then make spherical or rod-shaped glass products with smaller diameters. Then, it is heated and re-melted in different ways to make fine fibers with a diameter of 3-80 μm. The other type also melts the glass first, but produces glass fibers instead of rods or spheres. The sample was then pulled through a platinum alloy plate using a mechanical drawing method. The resulting articles are called continuous fibers. If fibers are drawn through a roller arrangement, the resulting articles are called discontinuous fibers, also known as cut-to-length glass fibers, and staple fibers.
According to the different composition, use and properties of glass fiber, it is divided into various grades. The glass fibers that have been commercialized internationally are as follows:
1.7.1 E-glass It is borate glass, and people also call it alkali-free glass in daily life. Because of its many advantages, it is the most widely used. It is currently the most widely used, although it is widely used, but it also has inevitable shortcomings. It easily reacts with inorganic salts, so it is difficult to store in an acidic environment.
1.7.2 C-glass is also called medium alkali glass in actual production. Its chemical properties are relatively stable and its acid resistance is good. Its disadvantage is that the mechanical strength is not high and the electrical performance is poor. Different places have different standards. In the domestic glass fiber industry, there is no boron element in medium alkali glass. But in the foreign glass fiber industry, what they produce is medium alkali glass containing boron. Not only the content is different, but also the role played by medium-alkali glass at home and abroad is also different. The glass fiber surface mats and glass fiber rods produced abroad are made of medium alkali glass. In production, medium alkali glass is also active in asphalt. Because of its very low price, it is widely used, and it is active everywhere in the wrapping fabric and filter fabric industry.
1.7.3 Glass fiber A glass is also called high alkali glass in production, it belongs to soda silicate glass, but because of its water resistance, it is generally not produced as glass fiber.
1.7.4 Glass fiber D glass It is also called dielectric glass, which is generally the main raw material of dielectric glass fiber.
1.7.5 The strength of glass fiber high-strength glass is 1/4 higher than that of alkali-free glass fiber, and its elastic modulus is higher than that of E-glass fiber. Due to its various advantages, it should be widely used, but Because of its high cost, it is currently only used in some important fields, such as military industry, aerospace and so on.
1.7.5 Glass fiber AR glass is also called alkali-resistant glass fiber. It is a pure inorganic fiber and is used as a reinforcing material in glass fiber reinforced concrete. Under certain conditions, it can even replace steel and asbestos.
1.7.6 Glass fiber E-CR glass is an improved boron-free and alkali-free glass. Because its water resistance is nearly 10 times higher than that of alkali-free glass fiber, it is widely used in the production of water-resistant products. Moreover, its acid resistance is also very strong, and it occupies a dominant position in the production and application of underground pipelines. In addition to the more common glass fibers mentioned above, scientists have now developed a new type of glass fiber. Because it is a boron-free product, it satisfies people's pursuit of protecting the environment. In recent years, there is another kind of glass fiber that is more popular, which is the glass fiber with double glass composition. In the current glass wool products, we can perceive its existence.
1.8 Identification of glass fiber The method of distinguishing glass fiber is very simple, that is, put the glass fiber in water, heat it until the water becomes open, and keep it for 6-7 hours. If it is found that the warp and weft directions of the glass fiber become less compact, then It is high alkali glass fiber. According to different standards, there are many classification methods of glass fibers, which are generally divided from the perspectives of length and diameter, composition and performance.