SU969417A1 - Sand for making semipermanent molds - Google Patents

Description

in addition, carborundum and ammonium fluoride in the following ratio of inh rediapton, wt.%: Corundum 10-15 Glins refractory 8-18 Carborundum 12-45 Refractory phosphate ores zapushchee 12-16 Amorium fluoride; Ionium 0.2-0.9 Graphite powder Remaining At the same time, as a phosphate refractory binder, the mixture contains one-substance aluminum phosphate with a density of 1.5-1.55 g / cm-or al, mochromo calcium phosphate, or aluminum-chromophosphate. The carborundum in the mixture has a high quality — a highly refractory material; it has high heat resistance, hardness, thermal conductivity, and an insignificant linear coefficient of thermal thermal expansion. a thin film consisting of S i 0. However, this disadvantage is significantly reduced by nshp-1ch in a mixture of corundum, clay, and phosphate, which are looking for a carborundum from a thin film about oxidation. Therefore, in molding compounds containing graphite, the danger of intense oxidation is eliminated or localized by protecting its surface with a complex of corundum, clay, carborundum and phosphate. Therefore, with a long-term high-temperature effect, the grains of graphite protected by glaze. And carborundum give the casting molds high performance properties. This makes it possible to increase the number of castings from one form and, naturally, reduce the cost price of the form. Graphite has a significant residual porosity, which requires a slightly increased binder consumption (aluminum phosphate, therefore, aluminum phosphate is taken by 1–4% more in molding sand compositions where the content of graphite powder is higher or lower by the corresponding percentage low content of graphite in the molding mixture. The effect of graphite on niio4HocTb (both wet and dry slightly, as well as on thermal physical and plastic properties. Monosubstituted aluminum phosphate (LFS) With an awn of 1.5–1.55 g / cm, aluminum-chromium-phosphate of a chrom-peak plant (lHrKFS), aluminum-chromophosphate of the Aktyubinsk plant of chromic compounds. raw j and after drying, heat resistance, thermophysical properties are identical to those of these characteristics at APS. At the same time, both APS and AHRFS, AHrKFS have high textures (above-) that retain high mechanical, thermochemical properties and heat resistance, G ins in refractory moldable mixture acts as a plasticizer and a stabilizer and the content largely determines jointly with corundum and phosphate / green strength and strength after TepMoo6pafSoTKK. In the presence of orthophosphoric acid or phosphates, it does not undergo the usual structural transformations, as a result of which it retains its adhesion properties, even at sufficiently high temperatures. The content of clay and corundum in the molding mixture is selected depending on the mass of the mold, because the more massive the shape, the higher the cheese should be, which, to some extent, the clay provides. Therefore, in the manufacture of forms it is necessary to take the upper value of clay (up to 18 wt.%). If the form is not massive, its clay content should be closer to the lower limit; (up to 8 wt.%). Accordingly, it is necessary to increase or decrease the percentage of corundum, which gives the form, especially its working surface, an increased hardness. At the same time, the strength properties of the form and its thermophysical properties change insignificantly. To ensure the mixture sets after pressing, it is necessary to take ammonium fluoride closer to the top one. its content limit (up to 0.9 wt.%). Introduction to the mixture of 0.2: 0.4 wt.% Fto-. crista ammonium provides an opportunity to increase the durability of the molding mixture up to 24-30 hours. As the content of ammonium fluoride increases, the strength of cheese slightly increases, and it does not increase, and is dry. No changes in the thermophysical properties of the form were observed in 1 depending on the percentage of ammonium fluoride. In tab. Tables 1 and 2 respectively show examples of formulating mixtures containing boundary values of the ingredients and their properties. The mixture according to the invention is prepared by runners, for which dry components are mixed in and mixed for 5 minutes, and then the phosphate binder is poured in a thin stream, without stopping the runners, and mixed for 10 minutes. Ready blend-out mixture; It takes at least one hour so that a preliminary interaction of phosphate with other materials takes place. Samples are prepared in special molds under a specific pressing pressure of 100 kgf / cm — and subjected to heat treatment at 270–300 ° C. Ia are then transferred into a furnace and crushers. under high temperature conditions (100Q C) during

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The use of the invention increases the amount of removal of castings in one form by more than 50, increases the resistance to abrasion, against the long-term high-temperature force effect of the casting on the form. All this also makes it possible to improve the quality of castings, to reduce the costs of non-cost manufacturing of products, an example of about 10-15%.

1 rafit ground electrolyte Alumochromcal phosphate of single-substituted phosphate dumophosphate ,,. , 52 g / cm Apyumochromophosphate Ammonium Fluoride

Property Durability when tested for compression, cheese, kgf / cm Durability at I, compressive test after heat treatment at, 256.03 339.14 338.19 kgf / cm 39.5 34.4 0.6

JP, a b l c a 2

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S.

". ВШШ". ". К | 3.859.7.7 4.8 19D 34.3 14 14 0.2 0.9 0.6 3.5633.859 338.19 27.81 339D4

20-35

20-35

,

244.76

319.27

0.98 0.69

Claims (2)

48 48 Claim 1. Blend for manufacturing semi-permanent casting molds, including graphite powder, corundum, refractory clay, phosphate compound, which, in order to increase the vitality of the mixture, reduce the heat treatment temperature in the first stage to 270-300 C and preserving the durability of the forms after heat treatment in the second stage, the mixture as a phosphate compound 35 contains a phosphate melt Binder and additionally carborundum and ammonium fluoride at the following ratio of ingredients, wt.%: 10.0-15.0 Bark nd Clay fire 8, 0-18,0 resistant Continued table. 2 20-35 20-35 20-35 20-35 " 84.80 301.17 319.27 284.80; 0.21 0.84 0.69 0.21 48 48 48 48 common aluminum No. 12.0-45.0 Carborundum Refractory phosphate 12.0-16.0 binder Fluoride 0.2-0, 9 Ammonium Graphite Residual powder 2. The mixture according to claim 1, is different in that it contains monosodium phosphate with a density of 1.5-1.55 g / cm L and aluminum-chromium calcium phosphate, or hummochromophosphate as the tuplaque phosphate binder. Sources of information that are considered in the examination 1. The author's certificate of the USSR 486844, cl. In 22 C 1/00, 1974. 2. Authors certificate USSR 601073, cl. On 22 of 1/18, 1975.