Ti-Ti5Si3复合梯度多孔材料孔结构调控基础

In view of the limitations of the properties of titanium, to improve the filtration accuracy of the titanium separation membrane from 0.5 microns to 0.02 microns, it is necessary to break through a lot of key technologies, including the refinement of particle size of raw materials and the improvement of fast cooling sintering process, and so on. In addition, the properties of the ceramic has many excellent performances, such as acid and alkali resistance, high temperature resistance, etc., but its brittleness and ceramic filters under the same precision conditions having lower permeability, are the problems in the practical applications in the urgent to be solved. The asymmetric metal-ceramic composite gradient porous membrane material can solve the problems encountered in the above practical application. In the study of such materials, it was found that Ti5Si3 gradient layer and Ti porous support layer is difficult to achieve co-sintering. At present, there is no research with the metal-ceramic gradient porous interlayer material and provide a control theory related to the research results of this preparation process. Therefore, this project aims to reduce the stress concentration at the interface by the compressive stress between the sintering expansion and the rigid die of the film through the limited sintering of the material interface, to solve the problems of sintering deformation and cracking. To work for the production of industrial products, the pore structures of metal-ceramic gradient porous material will be referred; and the basic issues of how to design and control this kinds of pore structure will be detailed studied.

鉴于金属钛自身特性的限制，要把现有非对称微孔钛金属分离膜的过滤精度从0.5微米提高到0.02微米，需要突破很多关键性技术，其中包括原材料粉末粒度的细化及快速冷却烧结工艺的改进等。此外，陶瓷自身特有的物性使其具有诸多性能优点，诸如耐酸碱、耐高温等，但其自身脆性及陶瓷基体同等精度条件下较低的透过性能是其在实际应用中亟待解决的问题。非对称金属-陶瓷复合梯度多孔膜材料可以很好的解决以上实际应用过程中遇到的难题。在研究该类材料的过程中，发现Ti5Si3梯度膜层与Ti多孔支撑层间很难实现共烧结。目前，还没有与金属-陶瓷梯度多孔层间原料匹配及工艺控制理论相关的研究成果对这一制备工序进行适当指导。因此，本项目拟通过材料界面的受限烧结、以膜层自身烧结膨胀与刚性模之间的压应力抑制界面处应力集中，解决烧结变形及开裂等问题；研究金属-陶瓷梯度多孔材料孔结构的设计与控制基础问题，指导工业化产品生产。

过滤分离是微孔金属膜材料的主要用途之一，而钛及其合金多孔膜材料因优异的力学及抗腐蚀性能，已得到了广泛应用。鉴于金属钛自身特性的限制，要把现有非对称钛金属微孔分离膜的过滤精度从0.5微米提高到0.02微米，需要突破很多关键性技术。非对称金属-陶瓷复合梯度多孔膜材料可以很好的解决以上实际应用过程中遇到的难题。Ti5Si3具有高熔点、高硬度、低密度、耐腐蚀等诸多优异性能，对其开展多孔膜材料的制备及性能表征研究，具有一定的理论意义与实际应用价值。本项目旨在通过研究Ti-Ti5Si3梯度复合多孔材料原料及工艺参数与孔隙性能之间的关系，揭示梯度金属-陶瓷多孔材料孔结构形成与演化规律，建立金属-陶瓷孔径梯度多孔材料制备技术原型，指导梯度金属-陶瓷多孔材料制备与孔结构表征。.本项目首次采用限域内原位反应烧结工艺制备了Ti-Ti5Si3复合梯度多孔材料。通过SEM对多孔材料孔结构进行分析，发现：制备的Ti-Ti5Si3复合梯度多孔材料基体孔隙尺寸为10～50 μm；膜层孔隙尺寸为0.1～0.3 μm，厚度1～3 μm，且膜层孔隙为连通孔。对梯度多孔膜层进行了XRD、EDS及XPS分析，确定了原位反应生成的多孔膜层物相成分主相为Ti5Si3相，次相为TiSi相、TiO2相。在原位反应烧结过程中，石英管内壁对金属钛多孔生坯产生烧结压应力，此应力有利于生坯表面原位反应的进行。由于Ti-Si系金属间化合物中Ti5Si3相化学性质最稳定，如果烧结过程中原位反应进行充分，最终获得的多孔膜层成分将是富钛硅化物Ti5Si3相。此外，还深入探讨了限域原位反应烧结工艺制备Ti5Si3复合梯度多孔膜的孔结构成形机理。通过本项目的研究，将为后续进行其他合金掺杂来提升和改善Ti5Si3复合梯度多孔膜综合性能的研究提供基础理论依据，也将促进高精度钛基梯度多孔膜材料的实用化。