- Time of issue:2020-08-27 00:00:00
1. Industry Description: Glass is a silicate non-metallic material formed by the main material of silica and other chemical substances through melting and mixing. The production process is: mixing quartz sand, sodium carbonate, feldspar, limestone and other chemical materials; melting them into liquid in an industrial furnace under a high temperature; further processing and cooling. Common glass, according to its production technology, functions, material and application fields, can be classified in different ways. But, during the production process of the glass, silicon carbide rods, silicon molybdenum rods, molybdenum electrodes and other tungsten molybdenum materials are widely applied in the sintering circle, the difference of glass components leads to the need of different sintering temperature, so requirements to silicon carbide rods, silicone molybdenum rods and tungsten molybdenum products used as heating materials are different.
2. Industry Classification:
① Quartz glass: The content of SiO2 is more than 99.5%. With a low coefficient of thermal expansion, high temperature resistance, good chemical stability, an UL-light and infrared light permeability, high founding temperature and large viscosity, quartz glass is difficult to shape and is often used in semiconductor, electric light source, optical communication, laser and other technologies and optical instruments.
② High silica glass: The content of the main component SiO2 is about 95% to 98%. High silica glass contains a small amount of B2O3 and Na2O, and its nature is similar with that of quartz glass.
③ Soda-lime glass: The sintering temperature of such glass is relatively low. Its main component is SiO2 and it also contains 15% Na2O and 16% CaO. Due to the low cost and the nature of being easy to shape, it is suitable for mass production. The output of Soda-lime glass accounts for 90% of practical glass. It can be used for making glass bottles and pots, sheet glass, vessels, light bulbs, etc.
④ Lead silicate glass: The main components are SiO2 and PbO. Lead silicate glass has a unique high reflective index, a high volume resistance, and a good wettability with metal. It can be used to make light bulbs, vacuum tube stems, crystal glassware, flint optical glass, etc. It also contains a large amount of PbO lead glass that can block X-rays and γ-rays.
⑤Aluminosilicate glass: The main components are SiO2 and Al2O3. The softening and deformation temperature is high. It can be used to make discharge bulbs, high temperature glass thermometers, chemical combustion tubes and glass fiber.
⑥ Borosilicate glass: The sintering temperature of the glass is relatively high. Its main components are SiO2 and B2O3. With good heat resistance and chemical stability, this glass is used to make cooking utensils, laboratory equipment, metal soldering seal glass, etc. Borosilicate glass takes B2O3 as the main component, has a low melting temperature and can resist to corrosion from sodium steam. Borate glass containing rare earth elements has a high reflective index and a low dispersion and is a new kind of optical glass. Phosphate glass takes P2O5 as the main component, has a low refractive index and a low dispersion, and is used in optical instruments.
3. Specific Application: According to the different components of glass, the temperature needed during the firing and melting circles of the production of different kinds of glass is different, ranging from 1,200 to 1,700℃. Silicon carbide rod (silicon carbide electrical heating element), as a common heating element in the glass industry, features a working temperature range of 800 to 1,400℃, so it is suitable for the production and processing of low-temperature glass. Because the operating temperature range of silicon molybdenum rod (molybdenum disilicide electrical heating element) is 1,200 ~1,800℃, for most special high-grade glass, the temperature required in the highest sintering temperature area of the industrial furnace is over 1,600℃, silicon molybdenum rod becomes an necessary heating material. In the mean time, since the internal environment of the industrial furnace used to sinter glass is harsh, the silicon dioxide protective film formed on the surface of silicon carbide rods and silicon molybdenum rods will be destroyed more rapidly, which will directly affect the service life of the rod body.
Good and bad silicon carbide rods and silicon molybdenum rods are intermingled in the Chinese market. Different sizes of manufactories use different processes and make different silicon carbide rods and silicon molybdenum rods of different quality and many products perform generally in the glass industry. Therefore, for the glass industry, to choose the prosper silicon carbide rods and silicon molybdenum rods as heating materials is particularly important for the control of the production process and product quality. Songshan silicon carbide rods and silicon molybdenum rods feature large density, high heating temperatures, as well as special treatment to the rod body with the production technique, so the rod body has a strong resistance to acid, alkali and other harsh environments. Especially Songshan hot bending silicon molybdenum rods with high density, high temperature and high performance three advantages perform rather well when being used in the glass industrial kiln and have a long service life, and due to which, it is favored by many well-known glass manufacturers at home and abroad.
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