SU761446A1 - Mixture for producing heat-insulating material - Google Patents

Description

The invention relates to compositions of insulating mixtures on liquid glass and can be used in industry for lining induction heaters.

Known heat-resistant concrete for lining induction heaters, including, wt.%:

A mixture of finely ground magnesite with 5% sodium silicofluoride 30

Small chamotte filler 25

Large chamotte filler 29

Liquid glass with a density of 1.37 16 [1]

Known refractory concrete has high mechanical strength, fire resistance and low solidification temperature of 20 ° C. However, due to the presence of a large amount of chamotte filler, its thermal conductivity is relatively high and equals 0.9-1.2 ——-.

m ° C

Known mixture comprising the components in the following ratio, wt.%:

Mineral fiber 60-70

Liquid glass with a modulus of 2.6 and a density of 1.1-1.3 g / cm ³ 30-40 [2]

The disadvantages of this mixture are:

- low mechanical strength (5–10 kg / cm ² ), due to a relatively small percentage of the binder, which makes it unstable to abrasion and weighing 2

loads typical of the inductors lining;

- high temperature of hardening 130-150 ° C, due to the absence in 5 of the composition of this mass of hardener of liquid glass. This temperature leads to fading textolite screeds and electrical insulation turns of the inductor.

The closest in composition and achievable result to the proposed is a mixture for the manufacture of insulating material, including mineral fiber, liquid glass and nepheline

sludge [3].

5 The disadvantage of this mixture is not high enough compressive strength of the material obtained from it when the latter is heated to 1100 ° C.

The purpose of the invention is to increase the compressive strength of the material after heating it to 1100 ° C.

This goal is achieved by the fact that the mixture for the manufacture of insulating material, including mineral fiber 5, liquid glass and nepheline sludge, contains the specified components

The following amounts, wt.%:

Mineral fiber 30-50

) Liquid glass 45-55

Nepheline slurry 5-15

761446

The technology for preparing the heat-insulating mixture for the lining of the inductor consists in the fact that at first the crushed mineral fiber is thoroughly mixed with nepheline sludge, then water glass is introduced and mixed again.

The inductor is molded into the resulting mixture in a formwork by thrombing or on a vibrating table. The molded inductor is allowed to stand for 5-6 hours, then the formwork r'asbprayut and the inductor is dried for 10-12 hours in a drying cabinet at a temperature of 80 ° C.

For testing, samples were prepared of different compositions of the proposed mixture, as well as samples from the mixture by source [3].

Table 1

Components, weight. % Mix by source [3] The proposed mixture sample sample one 2 3 one 2 3 four five Mineral fiber Styrofoam Granules Nepheline Sludge Liquid glass 15 five 74 6 ten 3 79 eight five 2 83 ten thirty · 15 55 35 12 53 40 ten 50 45 7 48 50 five 45

table 2

Mixture by source [3] The proposed mixture Indicator Unit sample sample dimensions one 2 3 one 2 3 four five Bulk weight g / cm ⁸ 0.32 0.42 0.55 0.64 0.58 0.52 0.47 0.41 Compressive strength at 1 = 20 ° С kg / cm ⁴ 48 67 86 60 55 50 42 thirty Coefficient of thermal conductivity W 0.095 0.14 0.2 0.3 0.25 0.2 0.17 0.14 m ° C Strength at KG 6 _ eight eleven 58 55 48 40 thirty compression after heating to P00 ° C cm ⁴

As can be seen from the table. 2, the proposed Yu mixture is somewhat inferior in its properties after solidification to the mixture according to its source [3]. However, after heating the samples to a temperature of 1100 ° C, the mixture according to the source [3] reduces its strength properties eight times (due to the burning of polystyrene foam and dehydration of nepheline sludge), while its compressive strength becomes six times less than the compressive strength of the proposed mixes. In addition, in the place of the burnt polystyrene foam in the mixture according to the source [3], cells were formed, the dimensions of which were 5–20 mm, and through holes were observed on the samples up to 20 mm thick.

Therefore, the mixture according to the source [3] cannot be used as the lining of the inductor due to the fact that it does not meet the requirements for the latter (compressive strength of at least 30 kg / cm ² after heating to 1100 ° С, absence of cells and through holes).

15

20

25

thirty

Claims (1)

Claim Mixture For the manufacture of thermal insulation material, including mineral fiber, liquid glass and nepheline sludge, characterized in that, in order to increase the compressive strength of the material after heating it to 1100 ° C, it contains these components in the following amounts, wt.%: Mineral fiber 30-50 Liquid glass 45-55 Nepheline slurry 5-15