Molding sands for glass matrix casting

Abstract

The invention discloses molding sands for glass matrix casting. The molding sands for glass matrix casting are prepared by performing mixing treatment on base sands and an adhesive. The base sands areprepared by the following components in percentage by weight: 50-65 percent of SiO2, 1-6 percent of Al2O3, 1-4 percent of ZrO2, 4-8 percent of K2O, 5-10 percent of Na2O, 1-5 percent of Ca2O, 6-10 percent of SrO and 6-10 percent of BaO, wherein the average particle size of the base sands is from 0.03mm to 2mm. By adopting the molding sands for casting provided by the invention, the base sands areobtained by CRT screen glass treatment, and the environmental protection problem of CRT screen glass recovery is solved; in addition, during crushing, a cleavage plane does not exist, the mechanical strength is high, and the thermal chemical stability is good, so that the production cost during casting production can be lowered, and the casting performance of the molding sands for casting is improved.

Description

technical field [0001] The invention relates to a molding sand for casting, in particular to a molding sand for glass matrix casting, which belongs to the technical field of casting materials. Background technique [0002] At present, the most commonly used casting sand is quartz sand. As an important casting auxiliary material, the sand consumption per ton of castings is more than one ton. The quality of castings produced by sand casting has a great relationship with the quality of casting sand. Modeling and core making The cost accounts for half of the cost of castings. Among the common casting defects, defects such as casting welding repair defects, cleaning work, sand holes, pores, peeling, and water leakage are basically caused by core-making factors, and waste products caused by the quality of casting sand The rate is about 6% ~ 10%. 60% of casting waste is caused by modeling and core-making factors. The quality of casting sand is not good, which will cause a lot of ca...

AI Technical Summary

Problems solved by technology

[0002] At present, the most commonly used casting sand is quartz sand. As an important casting auxiliary material, the sand consumption per ton of castings is more than one ton. The quality of castings produced by sand casting has a great relationship with the quality of casting sand. Modeling and core making The cost accounts for half of the cost of castings. Among the common casting defects, defects such as casting welding repair defects, cleaning work, sand holes, pores, peeling, and water leakage are basically caused by core-making factors, and waste products caused by the quality of casting sand The rate is about 6% ~ 10%. 60% of casting waste is caused by modeling and core making factors. The quality of casting sand is not good, which will cause a lot of casting waste

For quartz sand for casting, the disadvantage is that natural quartz sand is a crystalline crystal, and due to the anisotropy of the crystal, crystal cleavage will occur when it is broken, that is, it will break along the cleavage plane of the quartz crystal, resulting in broken quartz. The particle angle coefficient (the detection unit of the average grain shape of sand in the molding sand test, the smaller the angle coefficient is, the closer the sand shape is to a circle) is relatively large. Generally, the angle coefficient of the molding sand is required to be below 1.3, but the untreated quartz sand in actual production It is difficult to meet this standard for the angular coefficient. Excessively large angular coefficient will cause poor fluidity of the molding sand and a decrease in cracking performance, which is not conducive to the subsequent processing of castings. Moreover, due to the large specific surface area, too many auxiliary materials are added during the sand mixing process. It reduces the manufacturing cost and reduces the physical properties of the molding sand, which reduces the air permeability of the molding sand and increases the amount of gas generated, resulting in defects such as casting pores; and because the melting point of quartz sand is around 1750 degrees Celsius, and it is not compressible, it can be used When the casting temperature is low, the concession of the molding sand is not good, and the casting is prone to internal stress or cracking. The tighter the molding sand, the worse the concession. Sometimes adding sawdust to the molding sand can improve the concession, but adding too much Auxiliary additives further reduce the quality controllability of foundry sand and increase the risk of product quality

[0003] As an early audio-visual equipment, CRT has been widely used from the 1970s to the beginning of this century. At present, CRT has been basically replaced by liquid crystal and plasma display equipment, and the disposal of eliminated CRT equipment has become a big problem. , especially the display glass bulb of CRT equipment, as the main waste of CRT, its matrix is ​​glass, but due to the special performance requirements of CRT, strontium, barium, zirconium, cobalt, nickel and other types of glass are added to it. Therefore, it cannot be used as a glass raw material like flat glass or bottle glass, and it is treated as waste without corresponding harmless technical means.

CRT screen glass contains more than 60% of silica, as well as high melting point elements such as alumina and zirconia, and because the glassy substance does not have cleavage, it can be crushed and processed to achieve a nearly spherical angular shape coefficient. , and its refractoriness and expansion coefficient are close to quartz sand, so CRT glass has the potential to be used as raw sand for foundry sand. Because it comes from waste materials, its production cost is far lower than the mining cost of foundry quartz sand. And after treatment, better casting performance than quartz sand can be obtained. At present, the use of this aspect is still a blank field in China and the world.

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