SU1558610A1 - Composition of exothermal mixture - Google Patents

Abstract

The invention relates to exothermic mixtures designed to relieve thermal stresses in welds, to heat the profits of castings and the joined and weldable parts prior to welding and welding. The purpose of the invention is to create an exothermic mixture for obtaining from it flexible (with a bend angle of * 98 5 °) extended products using the slip method casting, realized in a semi-closed volume under conditions of limited access of air. An additional oxidizing agent — asbestos (10–20 wt.%) And silicate binder — a silica sol or its mixture with sodium silicate at a ratio of 1: 2 to 2: 1 — is introduced into the exothermic mixture including metal fuel, iron oxide and silicate binder. . The mixture contains 3-10% binder. Magnesium or its alloy with aluminum is introduced as a metal fuel. Along with asbestos oxidant in the mixture is iron scale, which is introduced into the mixture in an amount of 20-60 wt.%. 3 hp f-ly, 2 tab.

Description

The invention relates to exothermic mixtures designed to relieve thermal stresses in welds made by electric arc and gas welding to heat, weld, and weld.

The purpose of the invention is to create an exothermic mixture for the production of flexible extended products from it by the slip casting method, which can be used in semi-closed volumes under conditions of limited air access.

In the exothermic mixture, chrysotile asbestos Mg6 (Si4Of) H20 is used as an additional oxidizing agent as the cheapest and most common in nature. In the mixture, magnesium is oxidized by silicon oxide, water vapor and oxygen from the scale. A general form of the reaction scheme can be represented by the equation

16Mg + Mg6 (Si4Ofl) -H40 + PeE04 - - 22MgO - + 4Si + 3Fe + 4HC

According to the formula of chrysotile asbestos Mg6 (Si4HC) HgO mon consists of 43.3% SiO, 43.6% MgO and 13.1% H20, and if magnesium oxide is inert with respect to magnesium, then silica and water are active

As the silicate binder in the proposed composition, Si02 silica sol or its mixture with sodium silicate is used. This allows obtaining more durable samples, but at the same time the bend angle is reduced. The introduction of magnesium / aluminum alloy into the mixture makes it possible to increase the efficiency of the mixture by adjusting the heat release over time. The mixture is highly flammable, has a higher calorific value, 5 forms well, gives loose, easily removable slags. The mixture stably burns in a layer with a thickness of about 5 mm and above.

The exothermic mixture is prepared as follows (composition 3). For the preparation of 100 g of the mixture, 40.0 g of magnesium powder, 17.0 g of chrysotile asbestos, and 40.0 g of iron oxide are taken and poured into a container with 0.5 l of water. After mixing, add 3 g of silica silica (18% Si04, 0.4% Na40) and mix again. Then water is removed and sheets are obtained which are dried in air for 2-3 hours, and then they give the required shape and dry at 60 ° C for 2 hours. The moisture content of the product is not more than 2%. Samples are flammable.

The proposed composition makes it possible to manufacture stretched products with a bend angle of 10-30 and to improve the calorific value by 600-1000 J / g. The products ignite and burn easily in a layer 5 mm thick.

When this mixture is burned, no compounds harmful to human health or the environment are formed.

To heat complex profiles or pipes, an exothermic mixture layer on the profile surface is formed from a wet mixture. When it is necessary to heat the surface with a slight curvature, pre-dried flat plates are used, which

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five

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five

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five

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possess necessary flexibility with a bend angle 15-40.

In tab. Figures 1 and 2 present the data on the bend angle for flat plates.

dried to a residual moisture content of 2%.

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The proposed composition of the exothermic mixture can be used to heat pipes and other curved parts, complex profiles with a small radius of curvature, in structures with variable wall thickness, etc. and allows heating in a semi-closed volume under conditions of limited access of oxygen to the air.

Claims (4)

1. The composition of the exothermic mixture containing metallic fuel, iron oxide, silicate binder, characterized in that, in order to ensure production. from a mixture of flexible extended elements by the method of slip casting and using the mixture in a volume with limited air access, the composition additionally contains chrysotile asbestos, which serves as an additional oxidizing agent, and, as a silicate binder, is a silica sol in the following ratio of components, wt.%: Metal fuel Iron scale Chrysotile asbestos Silica sol 2. The composition of pop. 1, differing by HI and the fact that it contains magnesium as a metallic fuel. 3. The composition of pop. 1, characterized in that it contains magnesium alloy with aluminum in a 1: 1 ratio as a metal fuel. 4. The composition according to claim 1, characterized in that it additionally contains sodium silicate as a binder, introduced by silica sol in a ratio of 1: 2 to 2: 1. 15; 0, - 60.0. 20.0, - 60.0 10.0 - 20.0 3.0 - 10.0 Table 1 0.4 0.38 0.55 10.5 0.47 27.2 23.0 18.0 0.38 16.0 1990 1990 0.5 Easy to fire 30 flames 255 28 3380 3380 0.5 Easy to flame 5900 25 23 0.5 Effortlessly 25 flames from stopin 20 25 12,900 0.5 Ignites by stopping 20 15 18 11,800 0.5 From stop it is difficult to detect (there are failures) Magnesium alloy with aluminum (1: 1) 15 Iron oxide-i on 62 Asbestos 20 Sol SiOЈ 3.0 or a mixture of sol sodium 1: 2 3.0 or a mixture of SiOj sol: sodium silicate 3: 1 3.0 magnesium alloy with aluminum (1: 1) 40 Iron scale on Asbest AO 15 Sol SiOf 5 or mixture Sol SiOj: sodium silicate 1: 2 5 or mixture Sol 0.67 3.8 0.73 3.3 table 2 2666 0.5 Fire 23 varies 25 2900 7740 0.5 Inflamed 21 15 13970 0.5 Inflamed by 15 from sgopi 12 14 2000 0.5 Ignites - varies from stopin 18 15