SU850258A1 - Protective coating for ingot moulds and stools - Google Patents

Description

54) PROTECTIVE COATING FOR PALLETS AND PICTURES

one

The invention relates to foundry. production, in particular, to zgiditnymi coatings for pallets and molds when casting steel from above.

One of the drawbacks when casting steel from above is the welding of ingots to pallets and molds and the deterioration of the quality of metal products and the disruption of process flows between steelmaking and rolling production. The use of protective coatings is most effective for eliminating ingot ingots from pallets and molds.

A protective coating for pallets and molds is known, containing kyanene-sillimanite concentrate, zircon concentrate and the bond 1.

However, this refractory mixture has insufficient strength properties.

The closest in technical essence and the achieved result to the proposed is a coating, including a refractory filler, (diatomaceous earth), bentonin, water glass and water t.l However, the known coating does not provide the required durability of pallets and molds. In addition, the coating has poor sedimentation resistance.

The purpose of the invention is to increase the durability of pallets and molds.

To achieve this goal, the protective coating comprising a refractory filler, liquid glass and bentonite contains, as a fire-retardant filler, a kyanite-sillimanite concentrate in the following ratio of ingredients, wt.%:

Distin-sillimanite concentrate 32-37

15

43-58 liquid glass

Bentonite 10-20

The distyl-sillimanite concentrate and bentonite are introduced with a particle size of 0.10-45 KW, and the kyanite-sillimanate concentrate is introduced in the following composition, wt%:

A120z50

FeO0.70

3102.39.80

25

ZrOi7

CaO0.20

MgO0.40

Ti021.30

 ) 0.05

HiO 0.10

thirty

Disten-sillimanite concentrate with a content of less than 57 wt.% And Zr02 more than 1.3 wt.% Was previously considered technical by marriage and was not used for its intended purpose. It has been established by research that the kyanite-sillimanite concentrate, which had previously gone to waste (with a content of A below 57 wt.% And ZrO. Above 1.3 Bec.%) J can be used as a filler, i.e. Disten-sillimanite concentrate with a content instead of 57 wt.% and with a content of 45 instead of 1.3 wt.% has better refractory properties and, accordingly, is cheaper.

Bentonite in combination with dis.ten-forces lymanite concentrate has good sedimentation properties and unlimited resources. Bentonite TU-14-8-50-72 has a refractoriness, a volume weight of 1.20-1.30 g / cm and a mixture of bentonite with a distane-sillimanite concentrate when bonding liquid glass dramatically improves the sedimentation stability.

Distin-sillimanite concentrate in the amount of 32-37 wt.% (Optimally 34 wt.%) Has sufficient strength and provides the necessary refractoriness, good continuous coating of the working surface of the pallet, which protects against welding and destruction.

Dishen-sillimanite concentrate in an amount of less than 32% and more than 37% by weight is not suitable for use in the first case due to low refractoriness, and in the second case due to the fact that it does not provide solidity and uniformity of the coating and the necessary fluidity to implement the mechanized method application. Use as a bonded liquid glass with a density of 1.161, 20 g / cm (GOST 8264-56) in an amount of 58-43 wt.% (Optimally 50 wt.%) Provides a good crown ability of the mixture with the working surface, i.e. provides receiving a continuous covering in the mechanized way. After being coated, the mixture dries quickly. The work surface is smooth and smooth, white. Liquid glass in an amount of less than 43% and more than 58% by weight is not suitable, since in the first case the coating density is insufficient, in the second case the coating is uneven, thick, does not pass through the hoses — nozzle, or clogging system.

To improve the quality and reduce the cost of coating, and

Improvement of sedimentation stability and heat resistance additionally introduced bentonite in the amount of 1020 wt.% (optimally 16 wt.%). Bentonite in an amount of less than 10 and more than 20 wt.% Is not suitable; in the first case, the mixture is ineffective; in the second, it becomes thick, the hoses - nozzles (the tube often clogs them) pass badly through the system, the surface of the coating is uneven (bubbles

The density of the mixture is 1.35-1.65 g / cm- (optimal is 1.5 7 / cm). Such density gives the possibility of mechanizing the operation of applying the mixture to the working surface. Densities less than 1.35 and more than 1.65 g / cm are unsuitable; in the first case, the density is insufficient, a thin layer; in the second case, the coating does not pass well through the hose-nozzle system, the coating is uneven. The system is often heavily clogged.

To achieve the indicated density, a fraction with a particle size of 0.10-0.45 mm of kyanite-sillimanite concentrate and bentonite is required. With a fraction of 0.10 mm and more than 0.45 mm, they are not suitable; in the first case, Pors Lok is prone to caking; in the second case, the mixture passes badly through the hose-nozzle system.

Coating compositions and characteristics of their properties are given in Table. 1 and 2.

The coating is prepared using existing technology, i.e. The preparation of a coating based on distane-sillimanite concentrate and bentonite with the addition of liquid glass is carried out in a propeller-type red binder at a speed of 45 rpm. In order to maintain the coating components in a constantly suspended state, the mixing must be carried out continuously. The coating is applied to the working surface of the pallets and molds having a temperature of 120-250 s. The marking is made through a glass with a channel diameter of 60-100 mm. During the casting period, the metal boiling semi-calm and calm. The temperature of the metal to be cast is 1570-1630 ° C. The coating on the working surface of the pallets is applied with a spray gun at 5 atm. Compressed air or with a special machine.

The present invention allows to increase the sedimentation stability of the coating and the durability of the pallets and molds, eliminate the weld ingots and improve the surface quality of the castings.

Table 1

Density, g / cm 1.89 1.65 1.35 1.31

Drying time, min

at

The thickness of the coating1, 2 ty, mm

Fire resistance, since 1730

Sedimentation stability through

3-5 3-5

3-5 2-3 2-3 2-3

1.0 1.0-2.0 1.0-2.0 1.0-2.0 1730 1730 1730 1730

0.60 No No - No 0.10

Claims (2)

121 128 128 128 .121 785025 Claims The protective coating for pallets and molds, including refractory na. Full body, water glass and bentonite, characterized in that, in order to increase the stability of the pallets and molds, it contains a kyanite-sillimanite concentrate as a refractory filler in the following ratio of ingredients, wt.%: 88 Disthen-sillimanite concentrate 32-37 Liquid glass 43-58 Bentonite 10-20 Sources of information | taken in 1 name during examination Copyright Certificate of the USSR 632468, cl. B 22 C 3/00, 1976. 2. Accented for Japan W 53-99036, cl. 11A 213, 1978.