Preparation method of high performance precoated sand

Abstract

The invention relates to a preparation method of high-performance precoated sand, and belongs to the technical field of casting modeling. According to the preparation method, calcium stearate is added, calcium powder is added to increase the density of a sand core, so that the sand grains are arranged more densely, and the strength of a model (core) is improved; at the core making temperature, resin and the calcium stearate are successively softened and melted, the calcium stearate is uniformly distributed in the precoated sand to form an interpenetrating network, the flexibility of the resinis improved, the deflection of the shell model (core) is increased, and thus the thermal toughness is further increased; in the preparation method, silicon nitride has good mechanical properties, goodthermal shock resistance, low temperature creep and stable structure, the silicon nitride is a covalent compound with high bond strength and can form an oxide protective film in air, so that the silicon nitride further has good chemical stability, and the silicon nitride and silicon carbide can form strong bond; and a refractory filler composed of silicon nitride powder, fly ash, alumina powder and silicon carbide powder is added into the precoated sand to enable the high temperature resistance time of the precoated sand to be prolonged.

Description

technical field [0001] The invention relates to a preparation method of high-performance coated sand, which belongs to the technical field of casting molding. Background technique [0002] Coated sand refers to the molding sand or core sand that is covered with a layer of solid resin film on the surface of the sand grains before molding. The commonly used laminating process has two processes: cold method and thermal method. The cold method is to dissolve the resin with ethanol, add the raw sand for mixing and grinding, and the ethanol volatilizes during the sand mixing process, and then add the curing agent hexamethylenetetramine to coat the two on the surface of the sand grains to obtain coated sand. Due to the extremely low production efficiency of the cold film coating process, the thermal method is widely used at present. The key point of the process is that in the sand mixer, the raw sand preheated to a certain temperature is contacted with thermoplastic phenolic resin...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention: Aiming at the problems of low high temperature resistance and short high temperature heat resistance time of the current coated sand, a preparation method of high performance coated sand is provided

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