高分散超细Mo(W)-Cu复合粉体及近净成形过程研究

In order to resolve the processing difficulty and high cost of high performance and complex shape Mo(W)-Cu alloys, the project put forward a new research idea that is use gel-casting technology to directly prepare high performance Mo(W)-Cu alloys and parts with superfine or nano powder as raw material. The ultrafine/nano Mo(W)-Cu composite powder is obtained combined the mechanochemical and co-reduction methods, and the preparation mechanism is studied systematically. After the action mechanism among the powders and dispersant or other organic reagent are analyzed and clarified, the powder dispersion law in the slurry and the rheological behavior are explored. Through the effects of the powder characteristics and process parameters on its forming process and densification in microwave sintering are researched, the rapid densification rule of the superfine Mo(W)-Cu composite powder is revealed under the comprehensive action of the temperature field and the microwave field, focused on solving the problem of forming and densification process of homogenization. On this basis, the relate theory and technology of gel-casting of ultrafine/nano grain Mo(W)-Cu alloy are established. The results not only has an important role in the gel-casting technology itself to develop and expand the application areas, also has an important role in promoting the wide application of the Mo(W)-Cu alloys, and thus has important theoretical significance and application value.

针对高性能、复杂形状Mo(W)-Cu合金难加工成形及高成本的难题，项目提出以超细/纳米复合粉末为原料，采用凝胶注模成形技术直接制备高性能Mo(W)-Cu合金及零部件的研究思路。在系统研究机械力化学-共还原制备超细/纳米Mo(W)-Cu复合粉末的原理基础上，分析该粉体相互间及粉体与分散剂等有机物间的作用机制和分散规律，探索其浆料的流变行为，揭示原料及工艺参数对其成形过程和微波烧结中致密化过程的影响，重点解决超细Mo(W)-Cu合金复合粉末的均匀成形及快速均匀致密化等难题，建立超细/纳米Mo(W)-Cu合金凝胶注模成形的相关理论及技术基础。研究成果不仅对凝胶注模成形技术本身的发展和扩大应用领域具有重要作用，也对Mo(W)-Cu合金的广泛应用具有重要的促进作用，因而具有重要的理论意义和应用价值。

Mo(W)-Cu合金具有优良的性能，广泛应用于电工电子及航空航天等领域。传统方法制备的Mo(W)-Cu合金致密度低、成份结构不均匀、性能差。针对高性能、复杂形状Mo(W)-Cu 合金难加工成形及高成本的难题，项目在超细/纳米Mo(W)-Cu复合粉末制备基础上，结合凝胶注模成形技术直接制备高性能Mo(W)-Cu 合金及零部件。研究了球磨及还原工艺对纳米Mo-Cu 复合粉末的结构及性能的影响，分析了其还原热力学及机理，制备了晶粒约为20~65nm且具有“壳核”结构的纳米Mo-Cu 复合粉末，建立了钼壳形态及结构的调控方法；通过引入凝胶注模工序而发展的高浓度球磨-凝胶固相共还原工艺，则可有效避免粉体在制备过程中的团聚，降低还原温度，提高粉体分散性，制备的W-Cu复合粉末分散度高、均匀性好、平均粒径仅490 nm，粒径分布较窄，易于实现大批量低成本生产。针对Mo-Cu粉体特点，设计了非水溶性凝胶体系，即以正辛醇为溶剂，甲基丙烯酸羟乙酯为单体，1，6-己二醇二丙烯酸酯为交联剂，过氧化苯甲酸叔丁酯为引发剂，N,N-二甲基苯胺DMA为催化剂；在分析各种分散剂分散机理和分散效果之后，优选兼具静电阻止及位阻效应的silok-7050作为分散剂；研究了分散剂、单体及固相体积分数等因素对浆料流变行为及其固化过程影响规律，建立了可控固化手段，以保证浆料的顺利注模及坯体均匀性。研究了纳米Mo(W)-Cu复合粉末的致密化过程及其结构和性能的变化规律，得到了最佳的烧结工艺，制备了致密度为99.21%，硬度、抗弯强度、电导率、热导率及热膨胀系数分为229.1 HV、837.76 Mpa、24.97×106 Sm-1、176.57 Wm-1K-1、8.04×10-6 K-1，结构均匀，性能优良的纳米钼铜合金，并建立了其主烧结曲线，计算出其表观致密化激活能为317.2 kJ/mol。纳米Mo(W)-Cu复合粉末的微波烧结可轻易实现快速致密，节约70%的烧结时间和能耗，得到致密度为98.1%的钼铜合金。研究成果不仅保证了高分散纳米Mo(W)-Cu复合粉末和高性能Mo(W)-Cu合金的低成本规模制备，促进其在现代技术的广泛应用，同时也丰富了金属粉末凝胶注模成形相关理论。