(北京航空航天大学 材料科学与工程学院，北京 100091)
摘 要: 在精密铸造中，型芯的性能直接影响铸件内腔的精度及性能。氧化钙对熔融钛具有良好的高温稳定性，且在铸造后具有良好的易脱除性能。本文作者建立了热力学模型，对氧化钙陶瓷型芯的烧结初期进行模拟，并进行浇铸实验以验证氧化钙型芯在钛合金精密铸造中的低化学反应活性和无污染特性。根据型芯在900~1 600 ℃烧结范围内的烧结收缩量，计算出相应的吉布斯自由能以及烧结平衡常数。通过热力学方程 ，得到此温度区间内烧结反应的 =240 998 J/mol， =150.7 J/(K？mol)；计算得出的最低烧结温度与实际结果吻合较好。TC4合金浇铸实验验证了氧化钙型芯的强度满足钛合金浇铸要求并且其对铸钛界面无污染的优良特性。
关键字: 氧化钙；钛合金；精密铸造；陶瓷型芯；烧结模型
（School of Material Science and Technology, Beihang University, Beijing 100091, China）
Abstract:In precision casting, the ceramic cores can directly influence the casting’s properties and internal precision. The calcium oxide has an excellent chemical inertness to the melting titanium and the cores can be easily removed after casting. The CaO ceramic cores’ thermodynamic model was established to analyze its initial-sintering stage. Casting experiment was also designed to prove the cores’ low activity and contaminate. The model was established through the sintering shrink between 900 ℃ to 1 600 ℃, using formula , calculating the enthalpy and entropy of the sintering progress ( =240 998 J/mol, =150.7 J/(K？mol)). The theory sintering temperature fully agrees with the real sintering temperature. The experiment also verifies that strength is enough for titanium casting and its low activity satisfies the surface requirement of titanium alloy without any contamination.
Key words: CaO; titanium alloy; precision casting; ceramic core; sintering model
