The development trend of foundry industry in the future is green casting. It is the raw sand of casting auxiliary material that enterprises rely on to improve product quality, reduce production pollution, reduce casting costs and improve benefits. Fused Ceramic sand has become a new favorite in the casting process with a series of advantages such as less binder addition, high air permeability and high sand strength. This article mainly introduces the properties of green casting auxiliary material Fused Ceramic sand and its application in casting.
In the foundry production process, 20million tons of waste sand are discharged every year due to the use of natural silica sand or artificially broken silica sand, and silica dust is prone to produce silicosis and endanger the health of workers. Therefore, it is urgent to develop artificial special casting sand, and Fused Ceramic sand has become a new favorite because of its series of advantages.
Introduction to Fused Ceramic sand
Preparation and physicochemical properties of Fused Ceramic sand
Fused Ceramic sand is a kind of smooth sand obtained from calcined bauxite ore raw material, which is melted into liquid by electric arc furnace at high temperature, then blown into the air by strong wind, and then naturally balled by liquid surface tension.
The particle size of Fused Ceramic sand for casting is generally between 0.053 mm and 3.53 mm. The main chemical composition of Fused Ceramic sand is aluminum oxide (AI203) and silicon dioxide (SiO2). The typical chemical composition of Fused Ceramic sand is shown in Table 1. Because the mineral phase of fused Ceramic sand is mainly corundum and mullite, its refractoriness is generally ≥ 1800 ℃, and it is a kind of high hardness aluminum silicon refractory.
Fused Ceramic sand has high bulk density, high hardness and nearly spherical shape. It has unique advantages in terms of re-use and EPC filling sand in the casting process.
Fused Ceramic sand has high fire resistance and is suitable for casting steel, cast iron and other materials. In addition, due to its low thermal expansion rate, fused Ceramic sand can reduce casting defects such as casting veins and cracks caused by high thermal expansion rate in the casting process.
Characteristics of Fused Ceramic sand
1) Fused Ceramic sand has a fire resistance of more than 1800 ℃, good high-temperature chemical stability, and a pH value of about 7.7. It is a neutral material and can be used in the production of cast steel, cast iron and various non-ferrous alloys by various processes such as clay sand, self-hardening sand, sodium silicate sand, hot (cold) core box, shell mold, etc.
2) Fused Ceramic sand is an electrofusion material with compact texture and better durability than other artificial sand.
3) The expansion rate of Fused Ceramic sand after heating is about 1/5 of that of silica sand, which is roughly the same as that of staggered sand and slightly lower than that of chromite sand. As a molding material, Fused Ceramic sand can effectively prevent the expansion defects of castings such as veins.
4) The Fused Ceramic sand grain shape is nearly spherical, with good fluidity, small specific surface area, less amount of binder added, and low gas generation of mold and core sand. It can also make cores with complex shapes.