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Very warm glass of water with the performance characteristics of the old sand regeneration research

Author: WangJiNa
Tutor: FanZiTian
School: Huazhong University of Science and Technology
Course: Materials Processing Engineering
Keywords: Sodium silicate sand Heating Freeze Performance Characteristics Reproducibility Regeneration Modified silicate Hardening process
CLC: TG221
Type: PhD thesis
Year: 2009
Downloads: 233
Quote: 3
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Silicate sand toxic and tasteless, environment-friendly, experts believe that the 21st century is most likely to achieve the green sand casting, but to achieve silicate sand-based green water glass sand casting must address the regeneration problems. This paper studies the role of very warm water glass sand performance characteristics start pilot testing a very warm glass of water with dry sand and reclaimed sand regeneration performance; hardening process from the modified silicate and discusses two aspects of improvement in water glass Sand reclamation performance. Systematic study of the role of very warm water glass sand physical morphology and chemical composition. The results showed: under heat, heat temperature of 320 ℃ ~ 520 ℃, the sodium silicate sand adhesive membrane rupture of a large area, sodium silicate binder from the room temperature crystalline and amorphous composite structure into a single amorphous structure is conducive to stripping regeneration, as non-crystalline material than crystalline materials brittleness; freezing conditions, the freezing temperature of -10 ℃ ~ -40 ℃, the aqueous sodium silicate binder membrane surface will produce bubbles and ice crystals, water glass sand can also be achieved in the remaining amorphous binder changes and improve sand reclamation stripping ratio. The first real test of the role of very warm water glass sand-like mechanical properties, derived sodium silicate sand reclamation to the membrane mechanical conditions established to measure the old sand renewable mathematical relationship. Sand can get a better regeneration, the residual film could be damaged or larger can be removed by friction, the key is the old sand residual film on the mechanical properties of the size itself, that is its elasticity modulus E and the yield strength σ_s size. E / σ_s, the greater the residual film is greater the extent of the damage, the more easily regenerated sand. First practical process the water temperature measured at different mechanical properties of glass sand sample E / σ_s value to direct the reaction membrane mechanical properties of the binder. When sand samples were 320 ℃ ~ 520 ℃ heating, or sand samples -10 ℃ ~ -40 ℃ frozen, the sand kind of E / σ_s value larger than the adhesive film is easily removed collision or friction , sand renewable better. Frozen case, the moisture content of the sand samples and freezing temperature on the mechanical properties of sand samples greater impact. When a certain moisture content, the lower the freezing temperature, the sand sample E / σ_s larger values; freezing temperature is constant, the moisture content of about 10% of the sand sample of E / σ_s maximum value. Invented a water glass sand \Optimized process parameters \) and 120 ℃ ~ 520 ℃ \Liquid nitrogen cryogenic refrigeration and freezing the use of natural renewable water glass sand are feasible. Liquid nitrogen frozen water glass sand (temperature -40 ℃), the regeneration rate of up to 40% Tuomo; natural air frozen water glass sand (temperature -10 ℃ ~ -15 ℃), the regeneration rate of about Tuomo 32%. Experimental study of the regeneration process temperature on the properties of sodium silicate sand regeneration. Sodium silicate sand after 320 ℃ ~ 520 ℃ after the heat treatment, can make re-bonding properties of the reclaimed sand (strength, time, etc. can be used) greatly improved, but serious deterioration collapsibility; but after about -40 ℃ \Frozen - machinery \And non-heat treated reclaimed sand general mechanical dry compared: 320 ℃ ~ 520 ℃ \However, residual strength is also increased by about 35%, collapsibility deterioration; -40 ℃ \intensity decreased by 20%, collapsing better. Research and analysis of the high-temperature water glass sand silicate system response mechanisms proposed modified silicate material selection principles, chose solid mineral powder, liquid and nano-composite oxide powder and other materials on sodium silicate as modifier modified and the original sand Study. The results showed that: sand by the water glass and the original solid mineral powder additive compound with the corresponding modification, sodium silicate sand temperature strength increased by 30% to 40%, residual strength decreased 60% to 70%; liquid sodium silicate compound on change better resistance, strength at room temperature, about 16% of cases, the residual strength is decreased by about 78%; nano-oxide powder of the modified sodium silicate is not satisfactory; using solid mineral powder and liquid compound-modified modified The sodium silicate sand than ordinary glass sand has better cycling performance. Study tested the microwave curing process on the sodium silicate sand reclamation and reuse performance. Microwave hardening water glass water glass sand in addition is 1.5%, slightly higher than the 3% sand temperature strength dosage of sodium silicate ester cured sand-like, high-temperature strength of only residual ester cured sand sample of 1/7, collapsibility very Well, help to improve the sodium silicate sand reclamation and reuse performance; however microwave hardening silicate sand hygroscopic material requirements of the mold is higher. For microwave heating water glass sand mold materials require a higher issue, microwave reheating invented a new method of silicate sand, greatly reducing the microwave heating water glass sand mold material requirements, can be an ordinary wooden mold and plastic mold, improve the efficiency of microwave heating, microwave heating water glass sand process to make practical application to a major step forward. Experimental study of ultrafine powder hardening process for sodium silicate sand reclamation and reuse performance. When the powder is added in an amount of 25% of sodium silicate, the use of ultra fine powder particle size of 5μm, sodium silicate is added in an amount of 3% of the water glass sand sample temperature strength than the powder particle size of 70μm, sodium silicate added in an amount of 5% of the sand sample increased by 27%, the residual strength was reduced by about 85%; powder, sodium silicate sand hardened sodium silicate modulus of sensitivity is not high, the modulus of 2.7 using sodium silicate sand samples and the mold number of 2.3 water glass sand samples 24h strength less, but high modulus (2.7) silicate sand kind of residual strength ratio low modulus (2.3) silicate sand samples decreased by about 60%. Therefore ultrafine powder hardening process can be greatly improved water glass water glass sand sand collapsibility and reproducibility.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Casting > Casting of raw materials and preparation > Molding material
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