Zinc ingot mold coating and preparation method

Abstract

The invention discloses a zinc ingot mold coating, and belongs to the technical field of non-ferrous metal casting. The zinc ingot mold coating is used for coating the surface of an inner cavity of the ingot mold during casting of zinc and zinc alloy. The zinc ingot mold coating is composed of 20%-30% of graphite powder, 7%-10% of zinc oxide, 10%-15% of sodium-based bentonite, 5%-7% of aluminum dihydrogen phosphate, 5%-8% of sodium carboxymethyl cellulose, 8%-10% of quartz powder and the balance water. The preparation method for the zinc ingot mold coating comprises the steps that, the graphite powder, the zinc oxide, the sodium-based bentonite, the sodium carboxymethyl cellulose and the quartz powder are put into the water with the temperature being not lower than 60 DEG C at first; and finally the aluminum dihydrogen phosphate is added. When the zinc ingot mold coating is used, the prepared coating is sprayed on the surface of the inner cavity of the ingot mold with the temperature being 60 DEG C-80 DEG C. According to the zinc ingot mold coating, using is convenient, on-line using can be achieved, the appearance color of a zinc ingot or a zinc alloy ingot is uniform after the coating is adopted, and the appearance quality defects of black spots, dark spots and the like are completely overcome.

Description

Technical field [0001] The invention relates to a zinc ingot mold coating and a preparation method thereof, and belongs to the technical field of non-ferrous metal casting. Background technique [0002] In the hydro-zinc smelting technology, after the electrolytic zinc plate is melted, the liquid zinc is poured from the melting furnace into the ingot mold to solidify into an inverted trapezoidal zinc ingot. The current zinc ingot molds are mostly economical cast iron materials. During production, the zinc ingot molds are fixed on the conveying mechanism of the automatic casting machine (such as linear automatic casting machine, disc automatic casting machine), and liquid zinc is poured in After the ingot mold is moved, the liquid zinc is dissipated from the mold wall to complete the crystallization process, and then the solidified zinc ingot falls into the stacking process when the ingot mold reaches the turning position. In the current production practice, the zinc liquid has t...

AI Technical Summary

Problems solved by technology

In the current production practice, the zinc liquid has the following defects when it solidifies and crystallizes in the ingot mold: ① Due to the good wettability of the mold wall of the ingot mold and the liquid zinc and zinc alloy, the zinc ingot often sticks when it is demolded. mold phenomenon, resulting in a rough appearance of the zinc ingot; ②due to the slow cooling rate of the bottom of the ingot mold during the cooling and crystallization of the zinc liquid, especially the highest temperature at the pouring position, the cooling rate of the zinc ingot pouring position is quite different from other positions, resulting in After solidification, there are large black spots and dark spots on the bottom and surface of the ingot at the pouring position; ③ During the pouring and cooling process, a certain degree of chemical reaction always occurs at the contact interface between the high-temperature molten zinc and the ingot mold, and the pouring process is also liquid zinc During the scouring process on the surface of the ingot mold, a thin layer of zinc-iron compound layer is formed on the surface of the ingot mold as time goes on, and part of the zinc-iron compound layer falls off, resulting in erosion and corrosion damage of the ingot mold and shortening the service life

Due to the casting process of this ingot, the graphite layer is in contact with the liquid metal, which can obtain an aluminum ingot with uniform appearance quality, avoid the color difference defect of the ingot, and the cooling rate can also meet the production cycle requirements of the automatic pouring machine; but the graphite The strength of the inner layer is low, and it is prone to cracks and fractures, resulting in partial damage to the graphite layer. The replacement of the damaged graphite inner shell in mass production will affect the stability and continuity of production

[0004] Drawing on the construction principle of metallurgical furnaces, people apply refractory coatings on the surface of zinc ingot molds, which eliminates the color difference and black spots of zinc ingots, and obtains the appearance of zinc ingots with uniform color; but the poor thermal conductivity of refractory coatings increases the zinc ingot. The thermal resistance of the ingot / mold wall interface significantly prolongs the solidification time, resulting in a decrease in production efficiency; in addition, the thermal expansion rate of the refractory coating is quite different from that of cast iron, which is commonly used as an ingot mold material, resulting in partial peeling of the refractory coating, while the remaining Part of the paint is firmly bonded to the surface of the ingot mold and is difficult to remove, eventually resulting in uneven inner cavity of the ingot mold

People also use volatile paint to coat the surface of the ingot mold. Although the ingot mold is protected and the service life of the ingot mold is prolonged, there are burnt objects of the volatile paint on the wall of the ingot mold, and the pouring The process causes environmental pollution due to the burning and volatilization of the paint, so the volatile paint is not suitable for the coating of zinc ingot moulds.