采用线膨胀系数可控ZrO2-TiO2陶瓷模具的钛合金高精度超塑成形

对线膨胀系数可控的ZrO2-TiO2陶瓷模具及钛合金高精度超塑成形进行了系统研究。探讨了TiO2体积分数和相对密度对ZrO2-TiO2陶瓷的线膨胀系数的影响规律,并引入相对密度修正模型——Turner模型来准确预测复合陶瓷材料的线膨胀系数。采用压痕法检测了与TC4钛合金等膨胀系数的ZrO2-TiO2陶瓷模具的超塑成形精度。在925℃下,利用ZrO2-TiO2陶瓷模具进行超塑成形,其使用性能良好。结果表明:ZrO2-TiO2陶瓷的线膨胀系数随TiO2体积分数的增加而减小,随相对密度的增加而增加。采用线膨胀系数优化的ZrO2-TiO2陶瓷模具,成形精度误差大幅降低,不超过0.1%,且陶瓷模具具有足够的热机械性能进行超塑成形,使用性能优良。

High Precision Superplastic Forming of Titanium Alloy Using ZrO2 -TiO2 Ceramic Die with Controllable Linear Expansion Coefficient

The ZrO2-TiO2 ceramic die with controllable linear expansion coefficient(LEC) and the high precision superplastic forming were studied.The influence of TiO2 fraction and relative density on linear expansion coefficient of ZrO2-TiO2 ceramic was analyzed.The Turner model was modified and the relative density was introduced into the model.The forming accuracy of ceramic die with the similar LEC to TC4 titanium alloy was measured.The ZrO2-TiO2 deep cylinder ceramic die was fabricated and its performance was evaluated by the superplastic forming experiment at 925℃.The results show that the LEC decreases with the increment of volume fraction of TiO2 and increases with the rising of relative density.The modified Turner model more accurately predicted.Using the ZrO2-TiO2 ceramic die with optimal LEC,the forming accuracy deviation significantly reduced and not exceed of 0.1%.The ceramic die owns enough sufficient thermal mechanical properties and excellent performance.