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以水玻璃为粘结剂的熔模铸造壳型通常采用氯化铵作硬化剂,但由于氯化铵放出氨气,严重地恶化了劳动条件。近年来各地都试验和推广用结晶氯化铝代替氯化铵作硬化剂。 用结晶氯化铝作硬化剂的优点是:壳型常温和高温强度高,因而壳型尺寸稳定性好,铸件精度高;硬化过程不产生有害气体,改善了劳动条件;氯化铝溶液在工艺过程中变化缓慢,无需频繁的化验和补加新料;结晶氯化铝也有一些缺点,如渗透硬化速度慢,易产生粘砂;壳型残留强度大,脱壳困难。
Molten cast glass with water glass as a binder typically uses ammonium chloride as a hardener, but ammonium chloride releases ammonia and severely deteriorates working conditions. In recent years all over the test and promotion of crystalline aluminum chloride instead of ammonium chloride as a hardener. The advantages of using crystalline aluminum chloride as a hardener are that the shell type has high room temperature and high temperature strength and thus has good shell size stability and high casting precision; the hardening process does not generate harmful gases and improves working conditions; the aluminum chloride solution is used in the process Slow changes in the process, without frequent testing and additional new material; crystalline aluminum chloride also has some shortcomings, such as penetration hardening slow, easy to produce sticky sand; shell residual strength, shelling difficult.