型芯抗弯强度的影响因素及空心型芯的制备技术

采用不同工艺制备了精密铸造用型芯及强度试样,并对型芯的抗弯强度及型芯、铸件合格率进行了研究.研究结果表明,1 100℃下烧结的型芯抗弯强度及型芯的成品率均高于1 050℃烧结型芯的抗弯强度及型芯的成品率.室温下经低温强化型芯的抗弯强度高于“高温+低温”复合强化型芯的抗弯强度,而单独进行高温强化的型芯的抗弯强度最小.在1 350℃下,经高温强化和低温强化型芯的抗弯强度均高于9 MPa.硅溶胶高温强化型芯在1 350℃下的抗弯强度远低于采用硅酸乙酯进行高温强化的型芯.采用硅溶胶高温强化1 100℃烧结出的空心型芯,具有较好的抗弯强度及退让性的组合,而且其成品率较高,同时该工艺可提高铸件的合格率,降低铸件裂纹率.

Influencing Factors of Core Bending Strength and Preparation Technology of Hollow Core

By using of different techniques,we manufactured core and the strength test specimen for precision casting,and researched the bending strength of core and the qualified rate of cores and castings.The results show that the bending strength and yield of core sintered at 1 100 ℃ are higher than those sintered at 1 050 ℃.The bending strength at room temperature of core with low temperature strengthening is higher than that with high and low temperature composite strengthening;bending strength of core with only high temperature strengthening is the lowest.The bending strengths at 1 350 ℃ of the cores with high and low temperature strengthening respectively,were both more than 9 MPa.The bending strength at 1 350 ℃ with silica sol high temperature strengthening is much lower than that with ethyl silicate high temperature strengthening.The hollow cores sintered at 1 100 ℃ with silica sol high temperature strengthening possess well combination of bending strength and deformability,and higher yield,which improve the qualified rate of the casting and reduce the crack rate of castings.