不锈钢熔模铸造用镁基陶瓷型芯的研究

Study on Magnesium Based Ceramic Core for Stainless Steel Investment Casting

以氧化镁为主要原料,CaCO_(3)为矿化剂,添加木粉为造孔剂,采用压制成型工艺制备了不锈钢熔模铸造用陶瓷型芯。在氧化镁原料中加入CaCO_(3)矿化剂能促进陶瓷型芯的烧结,但加入量过多时,型芯的抗弯强度下降明显,而溶解溃散性的改善并不显著。加入5%CaCO_(3)矿化剂时,型芯具有较佳的综合性能。在此基础上,分别加入1%、3%和5%的木粉制备陶瓷型芯,随木粉加入量的增加,型芯的气孔率和溶解溃散性能明显提高,但也明显降低了型芯的抗弯强度。当木粉含量为5%时,型芯在醋酸溶液中溶解10 h的质量损失率达到70.12%,比未加木粉时提高了近40%,但抗弯强度下降了78%。采用添加木粉制备的陶瓷型芯浇注不锈钢试样,用浓度40%,温度80℃的醋酸溶液溶解去除型芯,添加5%木粉的型芯溶失最快,溶失速率为0.78 mm/h。本研究中型芯的溶解去除,醋酸溶液都是处于静止状态的,在实际应用中可以考虑采用搅动等方法增加溶液中的对流,促进型芯的溶解溃散。

The ceramic core for stainless steel investment casting was prepared by pressing process with magnesium oxide as main raw material,CaCO_(3)as mineralizing agent and wood flour as pore-making agent.Adding CaCO_(3)mineralizer to magnesia raw material can promote the sintering of ceramic core,but the bending strength of the core decreases obviously when the amount of addition is too much,and the improvement of dissolution and collapse is not significant.When 5%CaCO_(3)mineralizer is added,the core has better comprehensive performance.On this basis,the ceramic core was prepared by adding 1%,3%and 5%wood powder respectively.With the amount increase of wood powder,the porosity and dissolution and collapse performance of the core were significantly improved,but the bending strength of the core was also significantly reduced.When the content of wood powder is 5%,the mass loss rate of the core dissolved in acetic acid solution for 10 h reaches 70.12%,which is nearly 40%higher than that without adding wood powder,but the bending strength decreases by 78%.The ceramic core prepared by adding wood powder was cast with stainless steel samples,and the core was dissolved by acetic acid solution with a concentration of 40%and a temperature of 80℃.The core was dissolved the fastest when 5%wood powder was added,and the dissolution rate was 0.78 mm/h.In this study,the medium core was dissolved and removed,and the acetic acid solution was in a static state.In practical application,stirring and other methods can be considered to increase the convection in the solution and promote the dissolution and collapse of the core.