| 摘要 |
<p>Prodn. of a casting mould or core involves mixing a finely-divided inert refractory material and a binder and allowing the mixt. to harden. The binder consists of a water-soluble polymeric carboxylic acid (I), a finely-divided inorganic material (II), which reacts with (I) by leaching ions from it and forming a cement, water in an amt. of under 5% of the total wt. of the mixt. and min. 25 wt.% w.r.t. (I), tartaric acid, phosphoric acid and/or finely-divided MgO as modifier. (I) is pref. a polymer, esp. a homopolymer of acrylic acid. (II) is pref. a (fluoro)aluminosilicate glass. The sand left after casting contains no toxic constituents and can be recovered or dumped without the danger of environmental pollution. Tartaric acid retards wetting and improves the properties of the end prod., whilst the other modifiers also improve the properties, esp. the strength with phosphoric acid and the hardness with MgO.</p> |
