Ask Chemicals Gmbh

Joerg Kroker

Xianping Wang

Christian Priebe

Sritama Kar

Gregory P Sturtz

Mark Stancliffe

Kathleen Lowe

Kathleen E Lowe

Douglas J Desmit

Casting of non-ferrous metals, especially aluminum and magnesium, can have problems with erosion, in which molten metal contacts the mold or core surfaces during the pouring process, resulting in the sand being dislodged. Binder systems addressing this issue often use bisphenol F epoxy resin. A binder system is provided in which a major portion of the epoxy resin component is a bisphenol epoxy resin that has been modified by incorporating oxazolidone rings into an epoxy backbone of the bisphenol epoxy resin, especially a bisphenol A epoxy resin. The modification is preferably achieved by reacting the diglycidyl ether of the bisphenol with a methylene diphenyl diisocyanate.

Erosion resistant foundry shapes prepared with an epoxy-acrylate cold-box binder

Defects can arise in a product of a metal casting process from reactions occurring at a metal-mold interface. A method that reduces the defects uses an organic binder system by introducing a separate third component to a two-part polyurethane-based binder system used in the cold box or no bake process. The third part is added only after the first two parts are mixed with a refractory molding material to provide a shapeable foundry mix. The third part is an alkyl silicate, such as tetraethyl orthosilicate ('TEOS'), an alkyl orthoformate, such as trimethyl orthoformate (TMOF) or triethyl orthoformate (TEOF), or combinations thereof.

Method for reducing metal-mold reaction

A molding material mixture for producing casting molds for metal processing, particularly for non-ferrous metals, such as aluminum or magnesium, is intended to reduce problems such as metal-mold reaction and/or shrinkage porosity defect. The free-flowing refractory molding material in the molding material mixture is coated with a mixture of inorganic salts exhibiting a eutectic melting point in the range of about 400 C to about 500 C, particularly in the range of about 420 C to about 460 C. Preferably this coating occurs by contacting the inorganic salt mixture with the molding material mixture at a temperature between 500 C and 700 C, in a manner that maintains the free-flowing nature of the coated product. One mixture of inorganic salts that is used is a mixture consisting of, by weight: 74% potassium fluoroborate; 15% potassium chloride; and 12% potassium fluoride. This mixture has a eutectic melting point of 420 C.

Molding materials for non-ferrous casting

A 'cold box' process for forming a foundry shape by curing a binder in a foundry mix operates by sequentially introducing a first vaporous curing catalyst to a pattern containing the formed foundry mix, followed by introducing at least a second vaporous curing catalyst. By arranging the amounts of the respective vaporous curing catalysts and the contact times, as well as by using the less active vaporous curing catalyst first, the total amount of curing catalyst used to effect the cure is reduced. Carrier gas may be used with the respective vaporous curing catalysts. Typically, the vaporous curing catalysts are tertiary amines having between three and six carbon atoms.

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Powell, OH, United States of America

Joerg Kroker