Analysis of Advantages and Disadvantages of Alkaline Phenolic Resin Melted Ceramic Sand

In the production of steel castings, in addition to using silicon sand as the casting sand, special sand such as zirconium sand, chromite sand, fused ceramic sand (ceramsite) and olivine sand can also be used as the casting sand.


Advantage of Ceramic Sand

Fused ceramic sand is characterized by rounded grain shape, low thermal expansion rate and high fire resistance. It is an artificial spherical sand produced by melting bauxite raw materials with electric arc and atomizing with strong airflow, also known as Ceramic Sand. The main chemical components are Al2O3 and SiO2, with a small amount of Fe2O3 and TiO2, trace K2O and CaO, etc. The main mineral compositions are mullite and corundum, and the fire resistance is generally ≥ 1 800 ℃.


Advantages of Ceramic Sand Alkaline Phenolic Resin Sand

The process of Ceramic Sand Alkaline Phenolic Resin Sand for the production of steel castings has the following advantages: ① significantly reduce the amount of binder added by 30% - 50%, and the amount of resin added is controlled at 0.8% - 1.3%; ② Improve sand (core) precision and reduce machining allowance; ③ The casting surface quality is greatly improved and the surface roughness is reduced (the roughness is close to 50μm) ; ④ Reduce sand fall and cleaning workload (over 60%); ⑤ Reduce the emission of waste gas and sand to realize green production; ⑥ Improve the working environment, reduce dust, and reduce the probability of pneumoconiosis.


Ceramic Sand Alkaline Phenolic Resin Sand Can Cause Problems

However, because alkali is contained in the basic phenolic resin, sintering and crust formation problems exist in the process of basic phenolic resin melting ceramic sand. The ceramic sand near the casting is hard and not easy to be broken. When the old sand is regenerated, these hard shells have to be screened out, which reduces the reuse rate of old sand. Therefore, the key to further promote the process is to study the formation mechanism of sintered shell layer in the process of basic phenolic resin melting ceramic sand and put forward corresponding solutions.


The sintering problem in the process of basic phenolic resin fused ceramic sand is mainly caused by the formation of sintering necks between ceramic sand to bond the sand together under high pouring temperature or long-time high temperature. Sinter necks are mainly formed by accumulation and growth of surface elements of ceramic sand to concave angles between ceramic sand, where K and Si elements are easier to diffuse to concave angles. Alkaline phenolic resin introduces a high content of K alkali on the ceramic sand surface, which reduces the liquidus temperature of silicate and further promotes the formation of sintering neck.


Promotion of solutions

Chemical method plus thermal method regeneration technology is a new method developed in recent years [9], which can effectively reduce the content of alkali substances in molding sand. The basic principle is to uniformly mix the old alkali phenolic resin sand with the composite release agent (mainly acid, inorganic salt and water), heat at 250~500 ℃ to make the molding sand surface film react with the release agent, exchange ions, remove K and Na ions in the film, and finally further increase the heating temperature to 600~900 ℃ to remove the resin film. The chemical method with thermal method regeneration technology can greatly reduce the residual K, Na and other alkaline substances deposited on the surface of old sand.


Ceramic Sand Manufacturer

Sanmenxia Qiangxin Foundry Material Co., Ltd. is a specialized enterprise engaged in R&D, production and sales of casting auxiliary materials. Its main products include Ceramic Sand and resin-coated Ceramic Sand. The company's new molding material Ceramic Sand, known as "fused ceramic sand for foundry", has the advantages of high fire resistance, low expansion rate, high strength, low crushing rate, round particle shape, good collapsibility, etc. It is known as the green new casting material in the 21st century in the industry.