Current situation of wear-resistant castings
Wear-resistant castings (mortar wall, broken wall) are widely used in the abrasive wear conditions of mining, building materials, construction and other industries, and are usually produced by sodium silicate sand and resin sand process. Using sodium silicate sand molding process for production has many disadvantages, such as large amount of binder, difficult regeneration of old sand, poor recycling performance, and large discharge of solid waste such as molding sand; There are some problems in the production of resin sand molding process, such as toxic and harmful gas emissions, poor sand mold concession, large amount of molding sand solid waste emissions, VOC terminal treatment costs and comprehensive application costs.
What is Fused Ceramic Sand?
Fused ceramic sand, that is, spherical ceramic sand for casting, is an artificial spherical refractory particle of aluminum silicon system, which is formed by high-temperature melting of special and first-class high aluminum ore clinker in an electric arc furnace and blowing with compressed air. Fused ceramic sand has the advantages of uniform chemical composition, high fire resistance, good spherical and ball milling toughness, and stable thermal expansion rate (linear expansion). In the molding process, the binder has the advantages of low dosage, good collapsibility, strong wear resistance, easy collection and screening.
What is inorganic binder?
Inorganic binder is an aqueous solution of aluminosilicate prepared by autoclave (different from ordinary sodium silicate and modified sodium silicate). It has the advantages of non-toxic, odorless and smokeless in the casting industry, and can effectively reduce environmental protection costs and comprehensive application costs. The addition of inorganic binder is low, and the gas emission is only 1/10 of that of resin. It is environmentally friendly, and it can reduce the emission of waste gas and harmful gases greatly.
It is one of the casting materials with a wide range of applications. The addition amount of inorganic binder supporting products (curing agent and flocculant) is only 10% ~ 15% of that of inorganic binder, and more than 50% of the components are inorganic materials, which are applied in the form of two components. Flocculants are catalytic and adjusting materials, which are added in proportion according to the actual application situation. The hardening mechanism is water loss hardening and chemical hardening.
Application of fused ceramic sand wear resistant castings
The Mohs hardness of ceramic sand is grade 8-9, which is similar to the wear-resistant material brown corundum, and it is spherical. According to the microstructure observation, the bonding nodes and bonding bridges are mostly located at both ends of the ball, and the main material is adhesive residue, with a density of 0.8 ~ 0.9. By increasing the friction force and friction time, the production efficiency of sand regeneration can be effectively improved, and the fused ceramic sand will not be broken and worn under relative circumstances. In the molding process, because the ceramic sand has good fluidity, it can reduce the influence of the poor fluidity of the wet sand after mixing the binder, and at the same time ensure the compactness of the mold by using the vibration platform, which can reduce the amount of binder, improve the hardening strength and improve the production efficiency.
Using ceramic sand to improve the use of wear-resistant castings
The molding sand process of fused ceramic sand + inorganic binder + mechanical dry process sand recycling has the advantages of recyclable molding sand, low emissions of solid waste and toxic and harmful gases from used sand, and low comprehensive application cost, achieving the goal of reducing pollution, saving resources, and reducing energy consumption for foundry enterprises. It not only improves the production environment of the workshop, but also reduces the investment in environmental protection equipment.