Carbon-free precision casting method for evaporative pattern by adopting high-temperature ceramic coating gasification empty shell

Abstract

The invention discloses a carbon-free precision casting method for an evaporative pattern by adopting a high-temperature ceramic coating gasification empty shell, which comprises the steps of coating preparation, specifically, uniformly mixing the following components in percentage by weight: 8-12% of Guilin No. 5 and 88-92% of bauxite to obtain a powdery coating mixture, adding 60-80% of water, and stirring for 30 minutes; drying the coating, specifically, coating the surface of the EPS pattern with the prepared coating in a brush coating or dip coating or shower coating mode, and conducting drying layer by layer, wherein the drying temperature ranges from 50 DEG C to 55 DEG C, the drying time of each layer is longer than 4 hours, and the thickness of the coating is 5-6 mm or 8-10 mm; boxing and placing in a furnace, specifically, placing the EPS pattern in an iron barrel or an iron box to be filled with dry sand with the particle size being 3-5 cm; and conducting in-furnace gasification, specifically, controlling the gasification temperature of the EPS pattern to be 700-800 DEG C and the gasification time to be more than 40 minutes to obtain a casting mold. Compared with a traditional investment precision casting method, the method has the advantages that the process is simplified, the casting cost is greatly reduced, the production process is few and pollution-free, energy is saved, emission is reduced, and the casting is easy to clean.

Description

technical field [0001] The invention relates to the field of lost foam casting, in particular to a carbon-free precision casting method for lost foam using high-temperature ceramic coating gasification hollow shell. Background technique [0002] Lost foam casting is an advanced process technology for light weight and high efficiency in the 21st century. There are more than 4,000 lost foam casting companies in China, of which more than 1,500 use dry sand under negative pressure to burn the air first and then pour the molten metal. The technology, such as the Chinese patent published with the publication number CN101690976A, is called lost foam casting, which uses high-performance coating negative pressure combustion, empty shell pouring air flow rate, and cold elimination of carbon defects. This method has a huge breakthrough compared with traditional solid casting. The carburization defects of steel lost foam castings have been relatively well controlled, but due to the limi...

AI Technical Summary

Problems solved by technology

[0002] Lost foam casting is an advanced process technology for light weight and high efficiency in the 21st century. There are more than 4,000 lost foam casting companies in China, of which more than 1,500 use dry sand under negative pressure to burn the air first and then pour the molten metal. The technology, such as the Chinese patent published with the publication number CN101690976A, is called lost foam casting, which uses high-performance coating negative pressure combustion, empty shell pouring air flow rate, and cold elimination of carbon defects. This method has a huge breakthrough compared with traditional solid casting. The carburization defects of steel lost foam castings have been relatively well controlled, but due to the limitations of the burnout time and the structure and size of the castings, it is generally difficult to completely burn out the polystyrene foam in the mold (Expanded Polystyrene, referred to as EPS), the burnout degree is mostly in the range of 80-90%, which means that the threat of slight carbon increase still exists. For high-demand castings, such as weapons, military industry, national defense equipment, high-speed rail, aviation, aerospace, etc. The special castings equipped cannot meet the needs, and the EPS shape can be quickly and completely gasified without carbon residues only at temperatures above 700°C

If the imitation investment model hollow shell method is adopted, and the investment casting water glass or silica sol coating is used, the process is cumbersome, the production cycle is long, the coating curing process is polluting, and the energy consumption is astonishing, because it needs to be heated at 1000-1100 ° C Roasting for more than 2 hours can ensure the air permeability of the shell shape, and this kind of coating is not easy to be sanded and cleaned, so the popularization and application is not popular, the gain outweighs the loss, and less slow difference cost

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