玻璃纤维增强硅溶胶型壳的强度及高温自重变形

Strength and High-Temperature Self-Loaded Deformation of Glass Fiber-Reinforced Shell for Investment Casting

为了提高熔模铸造硅溶胶型壳的强度及高温抗变形能力,采用玻璃纤维来增强硅溶胶型壳。将玻璃纤维加入到制壳涂料中,制备硅溶胶型壳试样。对不同纤维加入量条件下所获得的纤维增强型壳试样的常温强度、焙烧后的抗弯强度、高温自重变形量的变化规律进行研究,并利用SEM观察型壳试样断口形貌。结果表明,随着玻璃纤维加入量的增大,其抗弯强度显著增大,高温自重变形量先增大后减小。当纤维加入量为0.6%时,试样的常温抗弯强度达到最大值4.61MPa;纤维加入量为1.0%时,高温自重变形量减少约24%。制壳涂料中加入0.2%~1.0%的玻璃纤维后,增强型型壳焙烧后强度提高至少12%。断口SEM形貌分析结果表明,纤维增强硅溶胶型壳试样的失效主要是由于硅溶胶凝胶膜的断裂、玻璃纤维拔出及脱粘等综合作用所致。

In order to improve the strength of silicon sol shell for investment casting process,glass fiber was mixed into the slurries to prepare the sol silicate shell samples.The properties such as bending strength of green shell,fired strength and self-loaded deformation at elevated temperature were investigated,and the fracture surface of shell samples were observed by SEM（scanning electron microscopy）.The results show that the green strength of shell specimens with glass fibers is increased,and the selfloaded deformation at elevated temperature is firstly increased and then decreased.The shell specimen reinforced with 0.6%fibers addition reaches the highest green strength of 4.61 MPa,and the self-loaded deformation at elevated temperature has a decrease of about 24% with the 1.0%fiber addition.The fired strength of shell sample with the concent of 0.2%~1.0%glass fiber is increased more than 12%.It is found by SEM that the failure of the fiber-reinforced shell specimens at the applied load is attributed to breakdown of silicon sol films and pulling-out and debonding of fibers in the shell.