The reason and prevention mehtod of the nodularization degeneration occuring in the surface layer of nodular iron castings produced with furan resin sand mould was introduced. Since the sulfonic acid was used as the hardening catalyst (hardener)of the furan resin,the sulphur it contained would penetrate into the surface layer of the casting at the high temperature and combine with magnesium,and as the result,the content of the nodularizing-active magnesium reduced and therefore the nodularization degeneration was caused. By decreasing the LOI of the reclaimed sand from 5.0% to 3.5%, using the low-sulphur G-51-Ⅱ and G-18-Ⅱ hardening catalyst to reduce the sulphur content of the furan sand,and adopting anti-sulphur penetration coating,the degeneration problem has been successfully solved and the qualified castings were produced.%介绍呋喃树脂砂球铁件表层球化不良的原因和防止方法.由于呋喃树脂砂采用磺酸做固化剂,其所含的S在高温下渗进铸件表层并与Mg化合,使起球化作用的w(Mg)量降低,因而引起球化不良.通过降低再生砂的酌减量(由5.0％降至3.5％),采用型号为G-51-Ⅱ和G-18-Ⅱ的低S固化剂、FQ10防渗S涂料,降低了型砂中的w(S)量,成功解决了铸件表层球化不良的问题.
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