SU529882A1 - Nonstick coating for casting molds and cores - Google Patents

Description

eight

Voda1O-13

Distin-sillimaniteOther

 Magnesitochromite (.Oj) is introduced into the coating in powder phase form and has the following chemical composition (wt.% T S

,

A “, OZ

8-12

Sa

S i O g2-4

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M O OST

Magnesitochromite has a high melting point (233 ° C) and a low coefficient of ",,,,, - .-) - IIIJ. - -. f

thermal expansion rate $% (l 90 10). , the introduction of magnesitochromite in. A composition of 2% in the amount of 2O-32% in combination with ssten-sillimaniton at the temperature of pouring steel forms a new phase, thereby ensuring the achievement of the goal set by JQ.

Magnesitochromite is produced by grinding magnesite to titicogram: k1fpi-

529882

cha (GOST 1O888-64) in ball mills to a fraction of 10O -JI5Q microns.

The preparation of the coating and its application to the surface of the foundry molds of the m and rods is carried out by the usual methods used in the foundry industry,

Pr im. 50 l of water, 4O kg of sulphite-yeast sconce, ki, 30 kg of submixed liquor and dry-mix agitator are added to the mixer with the dry components: 55O kg of distane-sillimanite, 25Ocg of powdered magnesite-chromite, then 2O kg of bentonite. After stirring for 10-15 minutes, the rest of the water (60 liters) is introduced, and stirring is continued for another 15-2 minutes.

In tab. 1 shows the formulations of the proposed coating.

The physicomechanical and technological properties of the coating of different composition are given in Table. 2

Table 1

Table 2 - . -; --- - When using the proposed coating, burns on castings are not observed. Increasing the amount of magnesite-chromite over 32% is not economically feasible, and reducing it to less than 2O% reduces refractoriness and impairs the quality of castings. The use of the proposed coating will allow to increase labor productivity and reduce labor intensity and the cost of manufacturing castings. The inventive non-stick coating for casting molds and cores, including kyanite-sillimanite, sulphite-yeast mash, podmilny lye, bentonite and water, characterized in that

Continued table. 2 NIN refractoriness and heat resistance of the coating and also improve the surface quality of castings, it is further soderzhitmagnezitohromit ingredients in the following ratio (wt.%): Sulfite-yeast Magnezitohromit20-32 brazhka2-4 Podmylny schelok2 - 4 Bentonit1-2 water-13 Kyanite-sillimanite Other Sources of information taken into account in the examination: 1, KM Tkachenko et al. Nonstick coatings for molds and cores. M.jMa Tire Engineering, 1963, p. 47. 2. Avt.Sv. No. 380390, cl. In 22 s. Z / oo 1971.