Environment-friendly precoated sand for high-strength castings and preparation method thereof

Abstract

The invention relates to environment-friendly precoated sand for high-strength castings and a preparation method thereof. The precoated sand comprises the following raw materials of, in parts by weight, 100 parts of raw sand, 4-8 parts of a binder, 1-2 parts of a curing agent, 0.1-1 part of a lubricant, and 0.1-0.5 part of a refractory particle, wherein the raw sand is a mixture of silica sand andceramic foundry sand, and the binder is modified phenolic resin. According to the method, the precoated sand raw sand are designed, the phenolic resin is modified, the refractory particles are added,the modified phenolic resin and the mixture of the silica sand and the ceramic foundry sand are fully mixed, so that the effect of the binder is effectively exerted; the ferroferric oxide refractoryparticles are mixed into the mixture of the silica sand and the ceramic foundry sand, the problem that the casting size is changed due to expansion in the casting process is inhibited, the precoated sand is fully ensured to be used at a higher temperature, the precoated sand has higher strength and better liquidity, the shape of the sand core can be ensure to be complete and compact, so that the surface of an inner cavity of the casting is smooth and free of burrs.

Description

technical field [0001] The invention relates to the field of coated sand materials, in particular to an environment-friendly coated sand for high-strength castings and a preparation method thereof. Background technique [0002] Resin-coated sand for foundry (referred to as coated sand) refers to the molding sand or core sand whose surface has been covered with a layer of solid resin film before molding and core making. Coated sand is generally made of foundry raw sand, thermoplastic phenolic resin, latent curing agent such as urotropine, and lubricant such as calcium stearate through a certain coating process. When the coated sand is heated, the resin coated on the surface of the sand grains melts, and under the action of the curing agent, the molten resin rapidly transforms from a linear structure into an infusible body structure, so that the coated sand is solidified and formed. [0003] Commonly used lamination processes include cold and thermal processes. The cold me...

AI Technical Summary

Problems solved by technology

[0004] Chinese patent CN108380814A discloses a regenerated coated sand for casting iron mold parts, including the following components in parts by weight: 100 parts of coated sand waste sand; phenolic resin, the amount of phenolic resin added is the amount of coated sand waste sand 1.0-1.4%; liquid silane, the amount of liquid silane added is 0.03-0.08% of the amount of coated sand waste sand; urotropine aqueous solution, the amount of urotropine added is 10-12% of the amount of phenolic resin , wherein, the weight ratio of urotropine and water is 1:4; calcium stearate, the addition amount of calcium stearate is 2-5% of the amount of phenolic resin, but its heat resistance is poor, easy to collapse , and the surface roughness of the mold made by it is relatively large, and it is easy to stick sand on the casting