RU2464144C1 - Composition for making electrode coating binder - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention may be used in making electrodes for manual electric arc welding of carbon and low-alloyed steels. Proposed composition contains the following components, in wt %: potassium-sodium silicate - 30.0-40.0 and water making the rest. Additionally, it comprises sodium sulphate in amount of 1.0-2.5 wt % of potassium-sodium silicate weight.

EFFECT: high-quality binder with sufficient viscosity at low costs of liquid glass.

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Description

The invention relates to welding materials, namely to the composition of the binder electrode coatings, and can be used in the manufacture of electrodes for manual arc welding of carbon and low alloy steels.

Known binder of electrode coatings, including an aqueous solution of alkali metal silicate, which is used as an unclarified leaching product of opal cristobalite rock containing 18-22 wt.% Undissolved residue (Patent RU No. 2070498, B23K 35/365, publ. 20.12.1996) .

A disadvantage of the known binder is the length of the manufacturing process of the electrodes due to the presence in the liquid glass of sludge in suspension, as well as in harmful working conditions when working with alkalis.

The closest in technical essence is a composition for the manufacture of a binder of electrode coatings containing potassium-sodium silicate, water and soda ash in an amount of 1.5-2.5% by weight of silicate. To obtain a binder, the silicate block is decomposed with its simultaneous dissolution in water (Patent RU No. 2036764, B23K 35/365, publ. 09.06.1995).

A disadvantage of the known invention is the high cost of the electrodes due to the content of soda ash in the binder electrode coatings.

The present invention is to develop a high-quality composition for the manufacture of a binder of electrode coatings with viscosity in a given range and low cost of liquid glass.

The problem is solved in that the composition for the manufacture of a binder of electrode coatings containing potassium-sodium silicate and water, according to the invention additionally contains sodium sulfate in an amount of 1.0-2.5% by weight of potassium-sodium silicate in the following ratio of components of the composition, wt .%:

Potassium Sodium Silicate 30.0-40.0 Water rest

A new technical result achieved by the implementation of the developed composition is that the introduction of sodium sulfate in the binder allows one to produce liquid glass of different viscosity during one cooking, which allows the manufacture of electrodes of different grades for which glass of the required viscosity is required, excluding the laborious process of adjusting the liquid glass, giving the necessary adhesive ability to the electrode coating. The adhesiveness of the binder is its important property, characterizing the ability to provide the raw strength of the finished coating mass. For an approximate stickiness measure of liquid glass, the mass of the cord is taken from the coating compound of a fixed composition when it is extruded at a constant speed through an opening with a diameter of 6.0 mm in the bottom of the cylinder, and also determined by organoleptic method. The obtained adhesiveness of the binder provides the standard depth of dents allowed on the surface of the electrode coating obtained from the frames when drying the electrodes. Reducing the cost of the binder is achieved by reducing the amount of potassium-sodium silicate (since liquid glass has a low viscosity after melting) and reducing the consumption of electricity and steam (reduced time for melting glass blocks).

The resulting binder is characterized by the following indicators: viscosity 0.35-0.75 Pa · s. When the content of sodium sulfate in the binder is less than 1.0% by weight of potassium sodium silicate, the necessary viscosity and adhesiveness of the binder are not ensured, which leads to equipment malfunctions, production of electrodes with poor coating quality and low sticking ability of the electrode coating (coating mass) to the metal rod, as well as to cracking of the coating.

When the content of sodium sulfate in the binder in an amount of more than 2.5%, an increase in the sulfur content in the deposited metal is possible above the required normalized values (not more than 0.03-0.045%, depending on the brand of electrodes).

Obtaining a binder of the proposed composition is as follows.

A potassium-sodium silicate block of the ASKN-1 brand and water are charged into the autoclave in a ratio of 35%: 65%. The block cooking time is 75 minutes at a vapor pressure of 0.4 MPa. After cooking, the resulting liquid glass from the autoclave is discharged into consumable containers. The finished liquid glass has a viscosity of 0.25 Pa · s. Before draining the liquid glass, sodium sulfate is poured into consumables in an amount of 2.0% by weight of potassium-sodium silicate, necessary to obtain a given glass viscosity of 0.6 Pa · s. The composition of the electrode charge contains, wt.%: Marble - 50.0, talc - 1.5, ferromanganese - 6.0, ferrosilicon - 6.0, cellulose 1.5, mica - 2.0, fluorspar concentrate - 15.0 , quartz sand - 9.0, ferrotitanium - 9.0. Dry electrode charge is poured into the mixer of the coating, where it is mixed in a certain proportion with the obtained binder. The amount of binder is 23% by weight of the dry mixture, and the viscosity is 0.6 Pa · s. Next, the coating mixture is applied to the electro-lubricating press on metal rods with a diameter of 5.0 mm from steel grade Sv-08A GOST 2246-70. The finished electrodes are laid out on a frame and dried at a temperature of 20 ° C for 24 hours, and then calcined in a chamber electric furnace at a temperature of 350 ° C for one hour. The permissible moisture content in the electrode coating after calcination is 0.2%.

Then, the quality of the obtained electrodes is checked. The welding and technological properties of the electrodes, the mechanical properties of the weld metal and the chemical composition of the deposited metal comply with the requirements of regulatory documents. The test results of various variants of the inventive binder composition for the manufacture of electrode coatings are summarized in table.

No. The number of components of the composition of the binder, wt.% Electrode Quality Indicators Potassium Sodium Silicate Water Additionally - sodium sulfate (by weight of potassium sodium silicate) The viscosity of the binder, PA · s Chipping coating when the electrode falls on a steel plate, mm The sulfur content in the weld metal,% Dent depth on the electrode surface,% of the electrode coating thickness one thirty rest 1,0 0.35 17.0 0.017 21 2 35 - // - 2.0 0.60 12.0 0,021 17 3 40 - // - 2.5 0.75 10.0 0,025 fifteen four 25 - // - 0.6 0.27 22.0 0.012 52 5 45 - // - 3.0 0.87 9.0 0,032 eleven

The table shows that the binders for the manufacture of electrode coatings of the claimed composition (examples No. 1-No. 3) have optimal properties and allow you to obtain the necessary viscosity (in the range of 0.35-0.75 Pa · s) for the manufacture of electrodes for welding carbon and low alloy steels. The maximum allowable sulfur content in the weld metal for electrodes of this brand is 0.03%. Partial chipping of the electrode coating after falling onto a steel plate should not exceed 20 mm. The depth of dents on the surface of the electrodes should not exceed 50% of the thickness of the electrode coating. The binder compositions (examples No. 4 and No. 5) do not allow to obtain the required quality of the composition that meets the regulatory requirements for the quality of electrode coatings intended for welding.

Thus, when using the proposed binder composition for the manufacture of electrode coatings with the claimed ratio of components, a high quality of the finished electrodes is achieved.

The proposed binder composition for the manufacture of electrode coatings for welding carbon and low alloy steels is industrially applicable, it is used in steel rolling at the site of manufacture of welding electrodes and allows manual arc welding with finished electrodes.

Claims (1)

The composition for the manufacture of a binder of electrode coatings containing potassium sodium silicate and water, characterized in that it further comprises sodium sulfate in an amount of from 1.0 to 2.5% by weight of potassium sodium silicate, in the following ratio of components of the composition, wt. %:
Potassium Sodium Silicate 30.0-40.0 Water rest