Water base casting coating for heavy casting and manufacturing method thereof

Abstract

The invention discloses a water base casting coating for a heavy casting and a manufacturing method thereof. The coating is composed of the following components according to proportion by weight: 65-75% of zircon powder, 20-30% of water, 0.8-2.5% of sodium bentonite, 0.1-0.6% of hydrophilic gaseous phase silica, 0.2-0.8% of waterborne polyurethane, 0.2-0.8% of polyvinyl alcohol, 0.6-2% of Water-based acrylic resin, 0.1-0.4% of butyl cellosolve, 0.1-0.3% of tributyl phosphate, 0.1-0.5% of ethylene glycol and 0.05-0.4% of isothiazolinone.The preparation method is advanced and feed compositions are effectively combined.The product features excellent technical indicators such as rheological behaviour, thixotropy, brushing property, suspension property, storage property, film-forming quality, brushing viscosity, thus being capable of meeting technical quality requirements in heavy casting production, in particular to the heavy casting which weighs more than 100 tons.

Description

Technical field: [0001] The invention relates to a casting coating, in particular to a water-based casting coating for large castings and a preparation method thereof. The coating is particularly suitable for the production of extra large castings weighing more than 100 tons. Background technique: [0002] As the basic industry of the country, the heavy equipment manufacturing industry plays a vital role in the national economy. Especially in thermal power, hydropower, nuclear power, military industry, steel, metallurgy, shipbuilding, petroleum, chemical, national defense and other heavy equipment manufacturing industries, large castings are the core components of these industries, and the quality requirements for large castings are particularly high. In the production of large castings, it is a very important process to apply casting paint on the working surface of the mold (core). Casting coating is a kind of refractory coating, and its main components are: refractory pow...

AI Technical Summary

Problems solved by technology

At present, the existing domestic water-based coating products cannot meet the technical quality requirements of large-scale casting production, especially the production of extra-large castings weighing more than 100 tons

For this reason, domestic also has numerous colleges and universities, scientific research institutes and enterprises to develop the required water-based casting coatings of large-scale casting production, but these water-based casting coating products of development are technically different from foreign products (such as the HOLCOFE produced by British Foseco Company). 110 water-based casting coatings), there is still a big gap, which cannot meet the technical quality requirements of large-scale casting production

Although the Chinese patent literature also discloses a name called "alcohol-based or water-based sand powder anti-penetration sticky sand casting coating" (publication number: CN1666828, publication date: September 14, 2005), its raw material components are complex and diverse, The batching and preparation procedures are complicated, the manufacturing cost is obviously high, and its technical performance indicators still cannot meet the technical quality requirements of large-scale casting production, mainly reflected in: 1. The performance of the brushing process is not good, and it is not suitable for large-scale casting production. Large area, multi-pass brushing operation

This is due to the improper selection of suspending agent, binder and other components or the improper collocation of each component, which makes the rheological properties of the coating unsatisfactory, resulting in poor process performance such as brushing, mainly manifested in the thixotropy of the coating ( Refers to the characteristics of some fluids that when shearing force is applied, its viscosity gradually decreases, and after the shearing force is removed, its viscosity gradually recovers) is poor, brushing in a thicker state (higher viscosity), The viscosity of the paint drops less when the brush moves back and forth, and the fluidity is still in a poor state. It feels sticky when brushed, and the resistance is large. When brushing a large area, it consumes a lot of physical strength of the operator, and the brushing efficiency is low; stop brushing. After that, the paint stops flowing in a short time, the paint film does not have enough time to self-levelling, and the dry paint film has heavy brush marks

If the viscosity of the paint is lowered and the paint is brushed, the brushability is improved, but when the brush is lifted from the container, the paint will be dipped less, and the paint will continue to drip down from the brush and drip on the painted film. The drip marks are formed; the paint tends to flow downward on the vertical surface and the surface with a slightly larger inclination, forming flow marks and a structure with a thin top and a thick bottom, and paint accumulation is prone to occur in the depressions of the sand mold (core); The thickness of the single-layer coating film is relatively thin. For the same coating thickness, additional brushing times are required to achieve it. It is not suitable for application in large-scale casting production.

2. The storability and stability of the paint are poor, and the viscosity is prone to drop during storage

Existing water-based paints mostly use sodium carboxymethyl cellulose, sodium alginate, hydroxyethyl cellulose, xanthan gum, etc. as thickeners. Corrosion ability is poor. During storage (especially in summer and autumn when the temperature is high), such organic thickeners are easily corroded and degraded by microorganisms such as bacteria even when the amount of preservatives is large, resulting in a large increase in viscosity. decline, and lead to deterioration of other properties of the coating

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