尼龙66纤维混杂刚玉砂对复合纤维型壳性能的影响

为了解决硅溶胶型壳在搬运、脱蜡过程中易开裂的难题,在撒砂材料中混杂尼龙66(PA66)纤维作为常温增强材料和成孔剂,制备不同PA66纤维质量分数的型壳。探究PA66纤维质量分数对型壳抗弯强度、透气性和气孔率的影响规律,并分析PA66纤维对型壳性能的影响机制。研究表明, PA66纤维大幅度提高了型壳的常温抗弯强度和透气性。随着PA66纤维质量分数的增加,型壳的常温抗弯强度和透气性均增大,焙烧后抗弯强度先增大后减小。当PA66纤维质量分数为0.75wt%时,综合性能达到最佳,焙烧后抗弯强度达7.94 MPa,与未混杂纤维的试样相差不大,但其常温抗弯强度达到4.80 MPa,比未混杂纤维的试样提高了32.21%,透气性和气孔率也增加至4.2和22.77%,比未混杂纤维的试样分别提高了90.91%和13.35%。

Effects of polyamide 66 fibers added to corundum sands on properties of composite shell

In order to solve the problem that the silica sol shell is easy to crack during handling and dewaxing, Polyamide 66(PA66) fibers were mixed into sand material as reinforcing material at room temperature and pore former to prepare composite shell with different PA66 fiber contents. The effects of PA66 fiber content on the flexural strength, permeability and porosity of the composite shell were investigated. The mechanism of PA66 fiber affecting the properties of silica sol shell was analyzed. The research shows that the mixing of PA66 fiber significantly improves the flexural strength and porosity of the composite shell at room temperature. With the increase of PA66 fiber content, the flexural strength and permeability of the composite shell increase at room temperature, and the flexural strength increases first and then decreases after baking. When the mass fraction of PA66 fiber is 0.75wt%, the flexural strength after roasting of the composite shell is 7.94 MPa, which is not much different from that of the composite shell without PA66 fiber. But its normal temperature flexural strength reaches 4.80 MPa, which is 32.21% higher than that of the composite shell without PA66 fiber. The permeability and porosity also increase to 4.2 and 22.77%, which are 90.91% and 13.35% higher than that of without PA66 fiber respectively.