撒砂层尼龙-氧化铝混杂纤维质量比对硅溶胶型壳性能的影响  

Effects of stuccoing layer nylon-alumina hybrid fibers mass ratios on the properties for silica sol ceramic shell

作　　者：陈义斯 芦刚 廖倚 毛蒲 陈晓 黄嘉俊 严青松 CHEN Yisi;LU Gang;LIAO Yi;MAO Pu;CHEN Xiao;HUANG Jiajun;YAN Qingsong(National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]南昌航空大学轻合金加工科学与技术国防重点学科实验室,南昌330063

出　　处：《复合材料学报》2023年第6期3449-3458,共10页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金(51861027);江西省研究生创新专项资金项目(YC2021-S672);南昌航空大学博士启动基金项目(EA202203058);轻合金加工科学与技术国防重点学科实验室开放基金(EG202103418)。

摘　　要：为优化高温合金精密铸造陶瓷型壳性能,采用“溶剂法”在刚玉砂中均匀掺入0.75wt%混杂纤维,制备不同质量比的短切尼龙纤维(Nsf)和氧化铝纤维(Asf)改性硅溶胶型壳。基于SEM观察型壳断口组织形貌,分析纤维分布及裂纹生长特征,揭示纤维和基体烧结演变及强化机制。结果表明,撒砂层引入纤维进一步提升了纤维在型壳内体积占比,型壳性能显著改善。柔性Nsf缠绕于刚玉砂粒表面,通过纤维拔出摩擦耗散载荷能量,同时Nsf烧失后形成原位孔隙增加透气性,故Nsf∶Asf为4∶1时型壳最佳湿强度、透气性、开气孔率分别为5.08 MPa、4.4、20.82%。此外,煅烧型壳基体易因脱水干燥萌生微裂纹,但裂纹扩展至Asf表面时发生分叉、偏转、增殖,证实立体互锁Asf网络结构减少连续裂纹产生,并抑制陶瓷颗粒剥离的沿晶断裂倾向。因此,Asf有效补偿Nsf烧失引起的强度损失,Nsf∶Asf为2∶3的样品烧结强度高达10.51 MPa,高温自重变形率仅0.82%。In order to optimize the properties of ceramic shell for superalloy investment casting,the 0.75wt%hybrid fibers were uniformly mixed in to the corundum sands via solvent method.Then,the short nylon fiber(Nsf)and short alumina fiber(Asf)modified silica sol shell were prepared with different fiber mass ratios.The microstructure of ceramic fracture was observed based on SEM,and the distribution patterns and crack growth characteristics of fibers were analyzed,which revealed the sintering behavior of fibers and matrix and further indicated the reinforcement mechanism.The results present that the properties of ceramic shell are significantly improved by a higher volume proportion of fibers in shell due to the stuccoing layer fiber addition.The flexible Nsf is wound on the surface of corundum sands,which dissipates the load energy by friction during the fiber pull-out process.Meanwhile,the Nsf is burned out and then form the in-situ holes in the matrix,which is beneficial to enhancing the permeability of shell.And the Nsf∶Asf=4∶1 sample shows the highest green strength,permeability and open porosity at 5.08 MPa,4.4,20.82%,systematically.In addition,the microcracks are easy to formed in the sintered ceramic shell because of the dehydration and drying However,the crack will be bifurcated,proliferated and deflected when it extends to the surface of Asf.The phenomena indicates that the interlock Asf network can effectively decrease the formation of continuous cracks,and further inhibits the ceramic particles striping and the intergranular fracture tendency for shell.Therefore,the Asf can effectively compensate the strength weaken caused by burned out Nsf.At last,the highest sintering strength of 10.51 MPa is obtained in the Nsf∶Asf=4∶1 sample,simultaneously,the high temperature self-loaded deformation rate of ceramic shell is only 0.82%.

关 键 词：混杂纤维 陶瓷型壳 精密铸造 纤维增强 高温合金 

分 类 号：V25[一般工业技术—材料科学与工程] TG242[航空宇航科学与技术—航空宇航制造工程] TB332[金属学及工艺—铸造]