Melt Infiltration Process
Melt Infiltration Process
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熔渗工艺
DOI：
10.1002/9783527622412.ch5
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
B. Heidenreich
中科院分区：
文献类型：
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作者：
B. Heidenreich
CMC材料在高温以及中低温下提供了独特的性能组合，这是任何其他材料如金属或单片陶瓷所无法实现的。然而，CMC材料也是非常昂贵的材料，这是由于高的原材料和工艺成本。通过在已有的CVI和PIP/LPI工艺基础上增加熔体浸渗工艺，可以部分消除这些缺点。MI工艺的特点是使用低成本的基质前体和碳纤维，在某些情况下，甚至不必涂覆，以及加工时间短。SiC基体在一个单一的工艺步骤中几乎同时在部件的整个体积中形成，并且不需要多个渗透循环来致密化C纤维和SiC纤维增强的CMC。因此，即使是非常大的、形状复杂的薄壁轻质结构以及非常厚壁的部件也可以在近净成形技术中实现。
与衍生自CVI和LPI的CMC材料相比，基于MI的C/SiC、C/C-SiC和SiC/SiC材料提供显著更低的开孔率，从而导致更高的剪切强度和热导率。然而，C/SiC和C/C-SiC的较低的拉伸强度以及SiC/SiC材料的有限寿命由基体中的游离Si引起，在高温下长期使用时对纤维的侵蚀仍然是一个挑战。
经过20多年的发展和在首次航空航天应用中获得的操作经验，MI-CMC材料刚刚走出实验室，成为工业市场的高性能产品。典型的应用领域是航天器的TPS结构，火箭推进、燃气轮机和核反应堆的热结构，热稳定结构和摩擦材料。C/SiC汽车制动盘的批量生产是CMC技术的突破和重要里程碑，为C/SiC和C/C-SiC材料在其他工业领域的进一步应用提供了很大的潜力。
未来的发展将不仅集中在低成本工艺和材料性能的改善以及环境屏障涂层上，还将集中在提供设计和模拟工具以及令人信服的非破坏性评估方法上。有了后者，科学家和工程师应该能够可靠地计算寿命以及损坏和故障行为，这是CMC组件在非常有前途但具有挑战性的安全关键应用领域中未来应用的基本先决条件。
CMC materials offer a unique combination of properties at high as well as at medium and low temperatures, which can not be achieved by any other materials like metals or monolithic ceramics. However, CMC materials are also very expensive materials due to high raw material and process cost. These drawback could be cut down partially by adding melt infiltration as an economically manufacturing process to well established CVI and PIP / LPI. MI processes are characterised by the use of low cost matrix precursors and carbon fibres, which, in some cases, even do not have to be coated, as well as by short process times. The SiC-matrix is build up almost simultaneously in the whole volume of the part in one single process step and no multiple infiltration cycles are needed to densify C- as well as SiC fibre reinforced CMC. Therefore, even very large, complex shaped and thin walled lightweight structures as well as very thick walled components can be realized in near net shape technique.
Compared to CMC materials derived from CVI and LPI, MI based C/SiC, C/C-SiC and SiC/SiC materials offer significantly lower open porosities, leading to higher shear strength and thermal conductivity. However, lower tensile strength of C/SiC and C/C-SiC as well as limited lifetime of SiC/SiC materials caused by free Si in the matrix, attacking the fibres in long term use at high temperatures are still a challenge.
After more than 20 years of development and of gaining operational experiences in first aerospace applications, MI-CMC materials have just found their way out of the laboratories into high performance products for industrial market. Typical application areas are TPS structures for spacecraft, hot structures for rocket propulsion, gas turbines and nuclear reactors, thermally stable structures and friction materials. The introduction of C/SiC automotive brake disks in serial production is a breakthrough and an important milestone in CMC technology, offering a high potential for further applications of C/SiC and C/C-SiC materials in other industrial areas.
The further development will not only be focused on low cost processes and the improvement of material properties and environmental barrier coatings, but will also concentrate on providing design and simulation tools in combination with convincing, non destructive evaluation methods. With the later, scientists and engineers should be able to reliable calculate lifetime as well as damage and failure behaviour, which is a basic prerequisite for future applications of CMC components in very promising, but challenging, safety critical applications fields.