SU931270A1 - Pickup preventing coating for casting moulds and cores - Google Patents

Description

(5) ANTI-GRUNTING COATING FOR CASTING FORMS AND RODS

; ... . . 1 The invention relates to foundry, in particular, to non-stick coating compositions for foundry molds and cores.

Known nonstick coating containing zircon, water glass, bentonite and water JV.

The disadvantage of this coating is the need to dry it at 150200 0 for 20-30 minutes or prolonged air drying. 12-15 as well as cracking of the coating at high temperatures.

The closest to the proposed technical. And the achieved result is a nonstick coating containing, in wt.%: Zircon, a metal phosphate binder (aluminum phosphate). liquid glass and water (an aqueous solution of liquid glass density of 1.2) 51-59 C2.

The disadvantages of the known non-stick coating are its low heat resistance, poor covering power and insufficiently high anti-stick properties.

The purpose of the invention is to increase the heat resistance, improve the covering ability of the coating and improve the surface quality of the castings.

This goal is achieved by the fact that the nonstick coating for t1Tejn1 forms and rods, including zircon, liquid glass, metalphosphate binder, and water, contains alumhbromophosphate and, in addition, bentonite, in the following ratio of ingredients, wt.%:

Zircon - 68-70 Liquid glass 5-7 AlyumokhromfosFat1, 5-1,8

2-3

Bentonite Water

Rest

Alumochromophosphate, interacting with liquid glass, forms a strong and at the same time plastic film that can withstand thermal stresses and completely eliminate the cracking of the nonstick coating at high temperatures and prevent the formation of burns on the castings. The introduction of bentonite into the nonstick coating improves the covering power of the coating and also increases its sedimentary stability.

The preparation of the coating is carried out as follows. Liquid glass solution is tight. 1.2 Phosphate aluminum 20.8 22.5 20, i Sedimentation stability after 3 hours, not less than,% 96 96 Coating strength Q C abrasion, kg / mm Covering ability Chorus. Choir Chorus

First, a liquid composition is prepared, for which a previously prepared 2.5-3, aqueous solution of aluminum chromium phosphate is introduced into liquid glass, bringing its density to 1.5-1.17 g / cm. Zircon and presoaked bentonite are introduced into the resulting liquid composition to a coating density of 1.9-1.95 g / cm.

Nonstick coating on the surface of the molds and cores is applied with a brush or spray gun. The coating hardens in air for 2 hours.

The compositions and properties of the nonstick coating are shown in Tables 1 and 2.

Table 1

Claims (2)

56 23.5 18.2 21.5 95 97 97 90 l 544 Choir Chorus Choir Satisfied, Thermal stability (the presence of cracks after a crack. A crack. A crack. T calcined with no no no n 2 h) The quality of the surface of the castings, flatness,% Density , g / cm 1.90 1.9 1.93 An increase in the amount of aluminum-chromophosphate in the coating of more than 1.8 masD leads to coagulation of liquid glass and the formation of burns on the castings, and a decrease in its content in the coating of less than 1.5 wt. | causes cracking of the coating at high temperatures. When the content in the coating is less than 2 wt. bentonite, its sedimentation stability decreases and the covering power deteriorates, and with a bentonite content of more than 3 wt.%, these properties increase slightly, but the cleanliness of the casting surface deteriorates. The use of the present invention will improve the heat resistance, the sedimentation stability of the coating, improve its covering ability and eliminate scorching. on the surface of steel castings. Claims of Invention Non-stick coating for casting molds and cores, including non-stick splitting, crackling. filament no no no pops. It has 15 fins and 1.90 1.95 1.93 1.6 zircon, water glass, metal phosphate binder and water, characterized in that, in order to improve heat resistance, improve coating color of the coating and improve the quality of the surface of castings, it contains as a metalphosphate binder, alumochromophosphate and additionally bentonite in the following ratio of ingredients, wt. |: Zircon68-70 Liquid glass Alumochromophosphate1, 5-1.8 Bentonite2-3 WaterOstalal Sources of information taken into account during examination Vashchenko KI, Drob zko V.N. Production of non-stick castings in sand molds. M., Mechanical Engineering, 1978, p. 130. 2. USSR author's certificate in accordance with ff, cl. B 22 C 3/00, 1979.