CS257128B1 - The bonding of powder coating electrode mixes for manual arc welding - Google Patents

Abstract

The binder of powder coated electrode mixtures for manual arc welding according to the invention eliminates the difficulties of previously used binders of coated electrode mixtures based on sodium-potassium water ice during their drying. It consists of an aqueous solution of polyvinyl alcohol, which is added in an amount of 5 to 15% by weight of the coating mixture.

Description

BACKGROUND OF THE INVENTION The present invention relates to a binder of powder coating compositions of electrodes for manual arc welding.

So far, sodium, potassium or mixed sodium potassium aqueous glass is generally used as the binder of the electrode powder coating compositions. In its composition it contains a considerable amount of water, whether free or crystalline, which it enters into the electrode casing. This is removed from the electrode package by drying at a temperature of about 200 ° C followed by electron firing at a temperature of about 350 to 400 ° C. Almost all of the water in the waterglass is removed at these temperatures, but pores and cracks are formed in the package, which are the atmospheric moisture adsorption sites. the weld, the cracking of the weld in the root and the like. The wetness of the electrode packs is a very serious problem and is largely due to the presence of water glass. Therefore, the coated electrodes must be re-dried at 200 ° C for at least 1 hour before use, which is not appropriate for economic, but also practical.

These disadvantages are largely eliminated by the binder according to the invention, which consists of an aqueous solution of polyvinyl alcohol in an amount of 5 to 15% by weight. packaging composition.

By using a new binder of powder coated electrode compositions, the following advantages are obtained: the wetting of the coated electrodes is reduced by approximately twice that of the electrodes using waterglass as a binder coated with electrode blends. Furthermore, the welding properties of the electrodes are improved operatively, using a new binder, particularly from the point of view of arc burning, finer crayon drawing and easy slag removability. An economical advantage is that the electrodes are dried at a lower temperature of 150-200 ° C for 2 hours. In terms of electrode hygiene properties as well as poor manual arc welding, they are the same as electrodes using waterglass as a binder.

The following examples illustrate the invention. A 6.5% by weight aqueous solution of polyvinyl alcohol was used as a binder in the production of a basic electrode for manual arc welding. wt. electrode blend. The electrodes after manufacture from the package of the invention were subsequently dried for 2 hours at 170 ° C. The dried electrodes were exposed to 84% relative humidity for 5 hours in humidifying chambers. The increase in moisture of the electrode casing with respect to its dry weight stated in% was 0.492 wt%, while the electrode using aqueous glass as a binder-coating electrode mixture was 0.9845 wt%. In another case, the inventive binder has been used in the manufacture of coated electrodes for manual arc welding of high alloy CrNi materials, wherein an aqueous solution of polyvinyl alcohol in an amount of 14% by weight has been used. for an electrode packaging composition.

The electrodes after manufacture were subsequently dried at 170 ° C for 2 hours. After exposing the electrodes to 84% relative atmospheric humidity for 5 hours, the electrode had an increase of 0.35% by weight, while the electrode using aqueous glass showed an increase of 0.680% by weight.

Welding electrodes made with a binder package according to the invention have been subjected to a drop test according to ČSN 05 5010 Welding and Welding Electrode Welding Electrodes and in both cases the electrode casing complied with the drop test.

The aqueous solution of polyvinyl alcohol according to the invention is suitable as a binder for electrode hand blends for manual arc welding.

Claims (1)

Binder of powder coating compositions of electrodes for manual arc welding, characterized in that it consists of an aqueous solution of a polyvinyl alcohol flow in an amount of 5 to 15 washes. by weight of the packaging mixture.