UA135599U - METHOD OF PREPARATION OF FILM-FORMING MATERIAL FOR CASTINGS - Google Patents

Abstract

A method of preparing a film-forming material for molds includes preparing an aqueous solution of caustobiolites containing humic substances and mixing it with liquid glass. As caustobiolites use carbonic reagent fraction of 0.1-0.5 mm with the number of insoluble organic components 5-20 wt. % by weight of water.

Description

The useful model belongs to foundry production, in particular to film-forming materials for non-stick coatings on the inner surface of casting molds, which prevent the formation of ingot defects when pouring steel in a casting mold.

There is a known method of preparing a non-stick coating, according to which caustobiolites, such as peat or lignite, are pre-neutralized with a saturated aqueous solution of sodium or potassium bicarbonate, brought to a paste-like state with water, after which the paste is heated to the beginning of boiling and cooled by introducing liquid glass in the volume, equal amount of paste (see author's certificate of the USSR Mo 1777975, IPC B22S 3/00, published on November 30, 1992).

The known method provides the possibility of using cheap and available raw materials - caustobiolites, and at the same time allows to achieve high thermal stability of this coating.

Disadvantages of the known method are the technological complexity of its implementation and the operational difficulties of coating the mold with a spray gun due to clogging of the outlet.

The closest analogue is the method of preparing a non-stick coating for casting molds, which includes preparing an aqueous solution of caustobiolites containing humic substances and mixing it with liquid glass | see stalemate. Mo 129332 of Ukraine, IPC В22С 3/00, publ. 25.10.2018). At the same time, humic peat extract, which is a purified aqueous solution of sodium humate obtained from lowland peat, is used as caustobiolite containing humic substances.

The use of ready-made humate peat extract when preparing the coating simplifies the process of preparing the coating. At the same time, the quality of the coating increases when it is applied with a spray gun without disturbing the process of painting the mold.

However, this method of obtaining a non-stick coating has a number of disadvantages, namely: the need to purify the aqueous solution of sodium humate from insoluble organic substances, which requires additional costs of humate peat extract during its production; insufficient protective properties of the coating due to the removal of solid particles, consisting mainly of cellulose and lignin, which does not ensure the formation of pulsed centers of lateral blowing, which prevent the contact of the pouring steel with the surface of the mold, and leads to the destruction of the working surface of the mold.

The basis of the useful model is the task of simplifying the method of preparing the film-forming material for castings and improving its protective properties.

The task is solved by the fact that in the method of preparing a film-forming material for castings, which includes the preparation of an aqueous solution of caustobiolites containing humic substances and mixing it with liquid glass, according to a useful model, how caustobiolites use a carbon-alkaline reagent of fraction 0.1-0, 5 mm with an amount of insoluble organic components of 5-20 wt. 95 from the mass of water.

The carbon-alkaline reagent is a loose powder, which is the product of the interaction of humic substances found in solid fuel (crushed lignite) with a concentrated solution of caustic soda, resulting in the formation of salt - sodium or potassium humate, depending on the alkali used in the technology. The carbon-alkaline reagent is used to treat drilling muds in order to reduce filtration rates, suppress and improve rheological properties.

The carbon-alkaline reagent contains soluble and insoluble organic parts: the soluble part is sodium or potassium humates, and the insoluble part contains a large amount of solid organic components - lignin and cellulose.

The proposed method is carried out as follows:

Pour 100 ml of water into a container with a stirrer, introduce the carbon-alkaline reagent in the given amount and fractional composition, mix for 30 minutes. Liquid glass with a volume of 100 ml is added to the resulting solution (density of liquid glass 1.4 g/cm3 GOST 13078-81). The resulting compositions are applied to a cast iron mold heated to 25076 using a spray gun with a hole diameter of 3 mm.

Well-known methods were used to evaluate the protective properties of the resulting film-forming material using a carbon-alkaline reagent: the adhesive strength was determined by the method of uneven separation of the film from the substrate under the action of a static load, when the load is applied only to part of the sample, spreading sequentially over its surface; water resistance - exposure of coating samples in water at a temperature of 20 C and a exposure time of 7 hours with further assessment of the condition of the materials; hardness of the coating - by the Shor method (pressing method); viscosity - on viscometer B3-4.

The table shows the protective properties of the non-stick coating according to the closest analogue and the film-forming material obtained by the proposed method, depending on its quality indicators.

As can be seen from the table, the film-forming material obtained by the proposed method and containing components within the stated limits is superior to the closest analogue in all controlled properties.

Table strength, N/m time unit. 4 p

The closest analogue: Extract and g

Humic // peaty, 140 13 0.05 40.0 mixed with liquid glass in a 1:1 ratio (Materials claiming it /|/Ї7711Ї111111111111Ї111111

EE viionyh WRITE NNYA NOYA NOYA solution, weight. 90 11111125... 171717117300 | (60 |4ЮХхсс05о0 | 300 11111205 7777777777771771111150.7.ЮЙ.| ЮЙЛ5 |. ю.009 | щ420

The coarseness of the carbon-alkaline reagent, mm with the content of the carbon-alkaline reagent 12.5 wt. In 711117117008777777777777171717111150..YUY.| 2 ЮюЮюЮюЯя2 юЮюЦ| 009 | 190 77771717171.y.70850....77777 1... 300 | 60 | 050 | 300

The use of a carbon-alkaline reagent fraction of 0.1-0.5 mm during the preparation of the film-forming material allows, without disrupting the coating technology, to ensure the formation of a gas layer between the film-forming material and the mold due to the combustion of solid organic components.

The fractional composition of the carbon-alkaline reagent is regulated by the technology of applying the film-forming material to the mold when using a spray gun and the amount of the gas phase.

When the size of the carbon-alkaline reagent is below 0.1 mm, the surface of the gas layer is insufficient to form a uniform coating of the mold. Partial welding of the metal to the form is observed. When the size of the carbon-alkaline reagent increases by more than 0.5 mm, the output hole of the spray gun is blocked and, therefore, the quality of the coating deteriorates.

The content of insoluble organic components in the carbon-alkaline reagent is below 5 wt. 95 leads to an increase in the bond strength of the film-forming layer with the mold and reduces its service life.

An increase in the amount of insoluble organic components in the carbon-alkaline reagent above 20 wt. 96 leads to a decrease in the bond strength of the film-forming material with the surface of the mold and, thereby, reduces the quality of the surface of the ingot.

Thus, a simplification of the method of preparation of the film-forming material for castings with an increase in its protective properties has been achieved.

Claims (1)

USEFUL MODEL FORMULA Coo) The method of preparing a film-forming material for castings, which includes the preparation of an aqueous solution of caustobiolites containing humic substances and mixing it with liquid glass, which differs in that, as caustobiolites, a carbon-alkaline reagent of a fraction of 0.1-0.5 mm with an amount of insoluble organic components is used 5-20 kg. 95 from the mass of water.