RU2478019C1 - Non-stick thermostable paint for sand and metal moulds (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to foundry production. The non-stick thermostable paint contains filler, bentonite and water. The filler is zircon powder and chromite powder, with the following content of components, wt %: zircon powder 25-35, chromite powder 40-50, bentonite 2.5-4.5, water - the balance. In another version of the paint, the filler is powdered disthene-sillimanite and olivine, with the following content thereof, wt %: disthene-sillimanite 35-45, olivine 30-35. In another version of the paint, the filler is magnesite and chromite, with the following content thereof, wt %: magnesite 20-35, chromite 45-55.

EFFECT: high quality of the cast surface owing to high thermostability of the paint.

3 cl, 2 tbl, 1 ex

Description

The invention relates to foundry technology, in particular to non-stick heat-resistant paints for sand and metal forms applied to the inner surface.

In the manufacture of foundry molds, the role of paints is crucial, because its effect affects the formation of the surface quality of castings (surface cleanliness, structure, physical and mechanical properties, including strength and size of the allowance for machining), as well as the operational resistance of metal molds. The main technological problem of using these paints is to provide high heat resistance and hiding power, providing high surface finish of castings and elimination of surface defects.

State of the art

From the patent literature, widespread use of heat-resistant coatings based on the following materials is known: distensillimanite and bentonite (AS USSR No. 1380846), zirconium dioxide with industrial oil (US Pat. No. 2297300), aluminum phosphate concentrate with graphite (US Pat. No. 2159164) and zircon powder with bentonite (US Pat. RF No. 2355505) - prototype.

General requirements for heat-resistant coatings are as follows:

- high heat resistance, ensuring a clean surface of the casting;

- high viscosity;

- high sedimentation stability;

- good hiding power;

- lack of toxic components.

The disadvantage of the prototype is the lower heat resistance of the paint and the low quality of the surface of the casting.

The technical result achieved by the invention is to increase the heat resistance of the paint and the surface quality of the casting surface.

SUMMARY OF THE INVENTION

Non-stick heat-resistant paint for foundry sand and metal molds contains a mixed filler based on mineral powders, a binder - bentonite and water, characterized in that a mixture of mineral powders - zircon and chromite, is used as filler, with the following components, wt.%:

 zircon 25-35  chromite 40-50  bentonite 2.5-4.5  water rest

Non-stick heat-resistant paint for foundry sand and metal molds contains a mixed filler based on mineral powders, a binder - bentonite and water, characterized in that a mixture of mineral powders - distensilimanite and olivine is used as filler, with the following components, wt.%:

      distensilimanite 35-45       olivine 30-35       bentonite 2.5-4.5       water rest

Non-stick heat-resistant paint for foundry sand and metal molds contains a mixed filler based on mineral powders, a binder - bentonite and water, characterized in that a mixture of mineral powders - magnesite and chromite, is used as filler, with the following components, wt.%:

      magnesite 20-35       lame 45-55       bentonite 2.5-4.5       water rest

Bentonite as a binder provides high strength. When the bentonite content is below 2.5%, the homogeneity is violated and the opacity is deteriorated, while the coating strength decreases. The overestimation of the content of bentonite leads to friability of the coating and its destruction. In tables 1 and 2 shows the compositions and basic properties of the proposed paint in comparison with the prototype.

The presence in the paint composition of powdered mixtures of fillers in an amount of 70-75% helps to obtain a coating with high heat resistance and improve the surface quality of castings. The combination of various fillers in the paint composition provides a wide range of thermophysical / dilatometric, physico-chemical properties, adhesive interaction, which contributes to the almost complete elimination of surface defects, with the exception of mixed blockages.

When the content of chromite powder in the claimed composition of paints var. Nos. 1 and 3 significantly improve the surface quality of the casting by reducing the roughness of both castings from stainless steels (var. 1) and castings from manganese steel (var. 3).

When the content of the filler mixture in the claimed paint composition is lower than 70%, it decreases its heat resistance, which leads to a deterioration in the surface finish of castings and an increase in roughness, and when the content of the filler mixture is higher than 75%, the sedimentation stability of the coating decreases, which leads to delamination of the paint. In addition, the hiding power of the paint and the uniformity of the application of the paint layer to the mold are deteriorated.

An example of the use of the proposed paint

Pre-ground powdered filler, as well as bentonite in the declared amounts, are mixed in a roller type mixer. Water is added to the mixed dry mixture, followed by aging. The viscosity of the suspension is checked on the sample taken. All materials used for the preparation of paint are not toxic.

The prepared paint is applied to the surface of the mold by spraying. The properties of the obtained castings using the composition of non-stick heat-resistant paint declared in the invention met all the quality requirements for the technical specifications.

table 2 Properties of non-stick heat-resistant paint Name of the physical and mechanical characteristics of the paint Quality indicators of paint Low content Suggested composition Completed Content Prototype Viscosity according to VZ-4, C 12.5 fourteen fourteen fourteen fifteen 11.5-12 Sedimentation stability,% 86 95 95 95 97 80-85 Surface quality of castings (defects) according to a 5-point system 3.0 (satisfactory) 5.0 (exc.) 5.0 (exc.) 5.0 (exc.) 4.0 (choir) 2.0-3.0 (mediocre) Abrasion resistance kg / mm ² 1,5 2.0 2.0 2.0 1,6 0.8-1.2

Claims (3)

1. Non-stick heat-resistant paint for foundry sand and metal molds containing filler, bentonite and water, characterized in that as a filler it contains a mixture of zircon and chromite powders with the following components, wt.%:
zircon powder 25-35 chromite powder 40-50 bentonite 2.5-4.5 water rest 2. Non-stick heat-resistant paint for foundry sand and metal molds containing filler, bentonite and water, characterized in that it contains a mixture of distensilimanite and olivine as the filler in the following components, wt.%:
distensilimanite 35-45 olivine 30-35 bentonite 2.5-4.5 water rest 3. Non-stick heat-resistant paint for foundry sand and metal molds containing filler, bentonite and water, characterized in that as a filler it contains a mixture of magnesite and chromite powders with the following components, wt.%:
magnesite powder 20-35 chromite powder 45-55 bentonite 2.5-4.5 water rest