Cast-iron evaporative pattern coating and preparation method thereof

Abstract

The invention provides a cast-iron evaporative pattern coating and a preparation method thereof. The cast-iron evaporative pattern coating comprises 84 to 88 parts of high aluminum powder, 8 to 12 parts of perlite, 8 to 12 parts of sepiolite, 6 to 10 parts of styrene-acrylic emulsion, 2 to 3 parts of sodium bentonite, 2 to 5 parts of white latex, 0.1 to 0.4 part of carboxymethylcellulose, 0.2 to 0.6 part of additive, and 105 to 120 parts of water. The coating of the invention has the advantages of uniformity and smoothness and good air permeability, and is easy to overcome the problems that the casting is easy to spray back and the local carbon is deficient, and the strength is high under the high temperature condition, which can eliminate the sticky sand and the collapse of the casting surface.

Description

technical field [0001] The invention belongs to the field of lost foam casting, and in particular relates to a cast iron lost foam coating and a preparation method thereof. Background technique [0002] Lost foam casting is to bond and combine paraffin or foam models similar in size and shape to castings to form model clusters. After brushing refractory paint and drying, they are buried in dry quartz sand for vibration modeling, and poured under negative pressure to vaporize the model. , a new casting method in which liquid metal occupies the position of the model, solidifies and cools to form a casting. At present, the lost foam casting process mostly adopts the direct pouring method, without burning the mold before pouring, and without vibration during pouring, so the requirements for the strength and air permeability of the coating are relatively high. Ordinary lost foam coatings have low strength after painting, and empty shells often collapse during vibratory pouring. ...

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Problems solved by technology

However, after the coating is thickened, the gas permeability of the coating will be reduced, so that the gas generated by the combustion of the pattern cannot be discharged in time before the empty shell is poured, and the combustion of the pattern is not sufficient, resulting in defects such as slag inclusion and local carbon increase in the casting after pouring; In addition, after the coating is thickened, it will also cause the casting to dissipate heat slowly, which will reduce the grain size of the casting and affect the mechanical properties of the casting.

[0004] Another way is to reduce the particle size of the coating aggregate, and increase the strength of the coating by using small-grained aggregates intensively, but this will also reduce the gas permeability of the coating and cause the above-mentioned defects in the casting

[0005] Moreover, the existing lost foam coatings have defects such as easy reverse spraying, local carburization, and sand sticking on the surface of the casting under high temperature conditions, and box collapse.

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