Development of controlled fracture forming process for advanced functional materials

陶瓷、金属间化合物及其复合材料的近净成形是传统塑性加工方法无法解决的问题。粉末成形技术有时不足以产生具有均匀特性或均匀形状的高质量功能产品。通过我们三年的研究项目，开发了可控断裂形成过程在基础研究的基础上，我们发现：（1）Ni/SUS 316-α Al_2O_3复合丝材的直径可达10米，均匀性好，直径可达300 μ m;（2）从初始密度较低的α-Al_2O_3预烧坯开始，大部分CFFP受剪切断裂过程控制，断裂颗粒在压缩压力约束下重新排列和流动;（3）布线和板成形的平均临界压下率接近90- 95%，其中绿色质量密度为90- 92%T。D.初始粒径为0.9 μ m时，平均粒径为0.3 μ m;（4）CFFP诱导的显微组织控制使烧结温度降低100-200 ℃，晶粒长大得到抑制，最终致密度达到99%。D.因此，该生产技术应作为未来实现精细陶瓷无粘结剂、无玻璃近净成形和显微组织控制的候选成型方法。

New alternative near-net shaping is indispensable to deal with ceramic, intermetallics and their composite materials since the conventional plastic working cannot be applied to these types of brittle materials. Usual powder forming technologies are sometimes insufficient to yield good-quality functional products with homogeneous properties or uniform shapes. Through our three year research project have been developed the controlled fracture forming process (abbreviated by CFFP) for ceramic composite wires and plates.On the basis of the fundamental studies, we have found that(1) Ni/SUS316-alphaAl_2O_3 wires with uniform diameter of 300mum can be produced up to 10 meters,(2) starting from the lower initial density alpha-Al_2O_3 pre-sintered billet, most of CFFP is governed by the shear fracture process with the fractured particle rearrangement and flow under the compressive pressure constraint,(3) the average critical reduction both in wiring and plate forming approaches 90-95%, where the green density of mass becomes 90-92% T. D. and the average particle size 0.3mum for the initial particle diamete 0.9mum,(4) good sinterability is attained by CFFP-induced microstructural control : the sintering temprature can be lowered by 100-200ﾟC, the grain growith is surppressed, and final density reaches 99% T. D. and more.Hence, this productive technology should be recommended as the candidate future forming method to realize nearnet shaping together with microstructural control for fine ceramics without binders and glasses.