新型复式连通SiC/390Al复合材料的制备和性能

以空心多孔SiC泡沫陶瓷为增强体,用挤压铸造法制备了新型复式连通双连续相SiC/390Al复合材料,研究了泡沫陶瓷骨架筋的结构对复合材料的影响,以及复合材料中的界面对力学性能的影响.结果表明,SiC空心多孔泡沫陶瓷与390Al复合后形成了复式连通双连续相复合材料,具有独特的互穿式界面结构,材料界面的结合优异.随着复合材料界面结合的加强和泡沫增强体的复合韧化,复合材料的屈服强度、压缩强度和弯曲强度明显提高,韧性显著增强.     

双连续TiC/Fe复合材料的制备和性能

以聚氨酯海绵为前驱体,以TiC微粉为原料并添加少量还原铁粉、羰基铁粉及钛粉为烧结助剂,用有机前驱体浸渍法制备具有三维网络结构的TiC多孔陶瓷,研究了聚氨酯海绵的孔径、浆料涂覆次数等因素对TiC多孔陶瓷的孔隙率和孔棱直径的影响。在此基础上采用无压浸渗工艺将Fe基体与TiC多孔陶瓷复合,制备出一种双连续结构的TiC/Fe复合材料。分析了复合材料的物相组成,观察了其宏观结构与微观结构,并测试了复合材料内的硬度分布。结果表明,TiC多孔陶瓷的结构完整,孔隙率和孔棱直径可控;复合材料具有双连续结构,TiC与Fe结合良好,两相结合区的硬度呈梯度变化。     

三维连续网络结构陶瓷／金属复合材料的研究进展

总结了国内外三维连续网络结构陶瓷／金属复合材料及其多孔陶瓷预制件在制备工艺方面的研究现状,分析了各种工艺的特点,介绍了这种新型复合材料在力学性能、热学性能、摩擦磨损性能、减震性能等方面的研究成果,并展望了三维连续网络结构陶瓷／金属复合材料的应用前景及其发展趋势。     

不同陶瓷颗粒增强Cu基复合材料的制备及导电性能

以纯铜为基体,以WC、AlN、TiN、MgB2等具有不同导电性能与密度的陶瓷颗粒为增强相,采用球磨-冷压-烧结工艺制备了WCp/Cu、AlNp/Cu、TiNp/Cu和MgB2p/Cu系列复合材料.研究了制备工艺的不同环节对铜基复合材料导电性能的影响,讨论了不同陶瓷颗粒增强铜基复合材料的导电性能.结果表明相同制备工艺及体积分数条件下,以具有不同导电性能与密度的陶瓷颗粒作为增强相的铜基复合材料的导电性能相近,球磨、冷压、烧结、复压及复烧等工艺环节对铜基复合材料导电性能有不同程度的影响,提高铜基复合材料的致密度为提高其导电性能的关键.     

聚硅烷陶瓷先驱体研究进展

具有σ-共轭结构特点的聚硅烷有着特殊的性能及用途。概述了聚硅烷作为陶瓷先驱体在制备陶瓷纤维、多孔陶瓷、陶瓷基复合材料3个方面的应用研究进展,并针对目前存在的不足指出了今后的研究方向。     

MAX相陶瓷增强金属基复合材料:制备、性能与仿生设计

由于原子间存在共价键、金属键与离子键的混合键合状态,MAX相陶瓷兼具金属和陶瓷材料的性能特点,并且常与金属之间表现出良好的润湿性,有助于形成强界面结合,独特的层状原子结构使MAX相陶瓷表现出良好的断裂韧性、阻尼与自润滑性能。因此,作为金属基复合材料的增强相, MAX相陶瓷具有显著优势,本文着重介绍相关研究进展。目前,MAX相陶瓷增强金属基复合材料主要通过搅拌铸造、粉末冶金和熔体浸渗等途径制备,得到的复合材料表现出优于金属基体的强度、硬度与模量,同时还具备良好的耐磨、导电、抗电弧侵蚀等性能。此外,借助真空抽滤、冰模板等工艺可实现超细片状MAX相陶瓷粉体的择优定向排列,然后利用金属熔体浸渗多孔陶瓷骨架,可获得具有类贝壳结构的MAX相陶瓷增强金属基仿生复合材料,进一步提升材料的强韧性能。MAX相陶瓷增强金属基复合材料在承载、电接触等应用领域具有显著优势和广阔前景。     

三维网络多孔陶瓷/金属复合材料的研究新进展

三维网络多孔陶瓷/金属双(共)连续相复合材料(C⁴材料)具有各向同性和正向加合性质,在摩擦器件和制动元件、电子封装材料及散热器件、航空航天器件、光学仪表材料、运动器械等领域具有广阔的应用前景。本文较为详细地介绍了C⁴材料的各种制备技术,并对比了它们的优缺点,在此基础上,重点阐述了本课题组提出的原位反应无压浸渗新工艺和最新研究进展,并对C⁴材料的未来发展趋势进行了展望。     

PIP结合CVI制备氧化铝-莫来石陶瓷基复合材料

通过PIP结合CVI法制备了C纤维增初三维氧化铝-莫来石陶瓷基复合材料,采用CVD法制备了防氧化涂层,研究了复合材料致密化过程、复合材料的物相、微观结构、力学性能和抗氧化性能。结果表明,CVI能够将氧化硅引入到多孔氧化铝基体内部,1400℃处理后氧化硅与氧化铝完全反应生成莫来石,显著提高了仅以PIP法制备的多孔氧化铝基复合材料的力学性能,CVD制备的氧化硅涂层有效阻止了氧气的侵入,复合材料在1200℃大气环境下保温50h后,试样三点弯曲强度保持率为70％。     

耐高温、高强度隔热复合材料研究进展

新型航天飞行器大面积热防护系统中,外部的防隔热层和机体内部冷结构之间一般需要用耐高温、高强度的隔热材料进行连接。在高温工业领域,隔热材料需要同时发挥隔热、承重功能。具有耐高温、高强度、低热导率性能的隔热材料在航空航天、高温工业等领域具有广阔的应用前景。多孔陶瓷因为其独特的多孔结构,具有较高的孔隙率、较低的热导率,被广泛应用于隔热领域。但多孔陶瓷材料的高孔隙率导致其强度较低,因此,近年来除开发新型高强度多孔陶瓷材料外,主要从选择合适的增强纤维和制备工艺优化方面不断提高多孔陶瓷材料的强度。目前,以纤维为增强体的纤维增强多孔陶瓷基复合材料,或者以纤维为基体的纤维多孔陶瓷材料研究成果较为丰硕,在充分发挥多孔陶瓷低热导率优势的同时大幅度提高了材料的强度。在具有较低热导率的多孔陶瓷基复合材料中,纤维增强纳米孔气凝胶隔热复合材料具有独特的纳米孔结构,其孔隙率很高、热导率很低且具有一定的强度;纤维多孔陶瓷具有由纤维与粘结剂构成的微米孔,孔隙率较高,其热导率虽高于气凝胶隔热复合材料,但强度较高、耐温性较好;纤维增强氧化物陶瓷基复合材料强度很高、耐温性也较好,但孔隙率较低、热导率较高。本文归纳了国内外耐高温、高强度隔热复合材料的研究进展,分别对纤维增强气凝胶隔热复合材料、纤维多孔陶瓷隔热材料、纤维增强氧化物陶瓷基复合材料的制备方法与相关性能进行介绍,分析了耐高温、高强度隔热复合材料面临的问题并展望其前景。     

SiC泡沫陶瓷/Fe基双连续相复合材料的制备和性能

将SiC泡沫陶瓷氧化,用挤压铸造法制备SiC泡沫陶瓷/Fe基双连续相复合材料并对其退火,研究了制备工艺和SiC泡沫陶瓷的体积分数对其微观组织和力学性能的影响。结果表明,在1250℃氧化48 h后在SiC泡沫陶瓷表面生成了厚度为1 mm的SiO2反应阻挡层。在双连续相复合材料的制备过程中,SiO2反应阻挡层抑制Fe与SiC的化学反应,避免了脆性化合物Fe3Si的生成,改善了基体与增强体的界面,使复合材料的抗弯强度提高2倍,压缩强度提高18%。当SiC泡沫陶瓷的氧化时间增至72 h时,SiC泡沫陶瓷表面SiO2的厚度过大。SiO2与基体和增强体热膨胀系数不匹配,使复合材料内相界面间的残余应力增加,导致其性能下降。将SiC泡沫陶瓷/Fe基双连续相复合材料在600℃退火4 h,可降低复合材料中的残余应力,提高复合材料的性能。SiC的体积分数较低时,金属基体的桥接、偏转裂纹的作用比较大,复合材料的弯曲强度高,变形程度大。随着复合材料中SiC体积分数的增大,SiC骨架筋增粗,其承载能力加强,复合材料的压缩强度呈提高的趋势。     

Erhöhung der Thermoschockbeständigkeit von Sinterglas und Keramik über das Verbundwerkstoffkonzept

Increasing the Thermal Shock Resistance of Sintered Glass and Ceramics by the Composite Materials Concept The thermal shock resistance of brittle materials such as glass and ceramics is one of their weaknesses. Pores and above all incorporated second phases in these materials alter these properties which are decisive for thermal shock behavior, and may therefore increase this behavior in a precalculable manner. The present paper will first theoretically demonstrate when and why porosity leads to an improvement in thermal shock resistance. The thermal shock resistance for porous borosilicate sintered glass and porous eutectic calcium titanate ceramic are calculated and compared to experimental values. They confirm

• that low porosities lead to an improvement in thermal shock resistance
• that the thermal shock resistance has a maximum at a certain porosity and
• that above certain porosities the presence of pores deteriorates the thermal shock resistance.

If one considers porous materials as a special case of composite materials then relations valid for composite materials can be transferred to porous materials (“composite material concept”) and viceversa. This is investigated using the examples of borosilicate sintered glass with incorporated antimony particles and eutectic calcium titanate ceramic with incorporated paladium particles. In the case of the glass-antimony composite material, improvements in thermal shock resistance of about 15% with 10 vol% antimony incorporation were calculated and confirmed experimentally, while for calcium titanate-paladium composite materials a 15% improvement in thermal shock resistance was already achieved with about 5 vol% of the metallic phase.     

高温隔热用微纳陶瓷纤维研究进展

陶瓷纤维具有密度低、强度高、耐高温、抗氧化和耐机械震动性能好等优点, 是空天飞行器、核能发电和化工冶金等热防护领域所需的关键高温隔热材料。传统陶瓷纤维直径粗(?>5 μm)、脆性大、热导率高, 在实际隔热领域应用中受到了极大限制。减小纤维直径, 制备微纳陶瓷纤维, 不仅有利于提高纤维力学性能, 还有望改善其高温隔热性能, 近年来引起了研究者的广泛关注。从微纳陶瓷纤维中影响热传输(气体热传导、固体热传导和辐射传热)的本征因素出发, 有针对地进行组成和结构优化, 进而改善其高温隔热性能, 是当前微纳陶瓷隔热纤维研究的重点方向。本文结合国内外研究现状, 在介绍微纳陶瓷纤维隔热机理的基础上, 按照纤维的组成和结构特点将目前微纳陶瓷隔热纤维分为三类, 即微纳陶瓷纤维气凝胶、中空/多孔微纳陶瓷纤维和复合微纳陶瓷纤维。对这三类不同特点的微纳陶瓷隔热纤维最新研究进展进行综述, 并展望了微纳陶瓷隔热纤维的未来发展方向。     

Theoretical and experimental considerations on the thermal shock resistance of sintered glasses and ceramics using modelled microstructure-property correlations

The thermal shock resistance of brittle materials such as glass and ceramics is one of their weaknesses. Pores and other incorporated second phases in these materials alter these properties which are decisive for thermal shock behaviour, and may therefore increase this behaviour in a precalculable manner. It has been theoretically demonstrated when and why porosity leads to an improvement in thermal shock resistance. The thermal shock resistance for porous borosilicate sintered glass and porous eutectic calcium titanate ceramic have been calculated and compared to experimental values. The results confirm that low porosities lead to an improvement in thermal shock resistance, that the thermal shock resistance has a maximum at a certain porosity, and that above certain porosities, the presence of pores deteriorates the thermal shock resistance. If porous materials are considered as a special case of composite materials, then relations valid for porous materials can be transferred to composite materials and vice versa (composite concept). This has been investigated using the examples of borosilicate sintered glass with incorporated antimony particles and eutectic calcium titanate ceramic with incorporated paladium particles. In the case of the glass-antimony composite material, improvements in thermal shock resistance of about 15% with 10 vol % antimony incorporation, were calculated and confirmed experimentally, while for calcium titanate-palladium composite materials, a 15% improvement in thermal shock resistance was already achieved with about 5 vol % metallic phase.Deceased.     

成型温度对多孔SiC陶瓷性能的影响

以包混工艺合成了核-壳结构的先驱体粉体,并引入少量Al<,2>O<,3>,SiO<,2>和Y<,2>O<,3>作为复合添加剂,通过模压成型、炭化和烧结工艺制备了多孔碳化硅陶瓷;研究了成型温度对样品的孔隙率、密度、热膨胀系数、抗弯强度和热震性能的影响.结果表明:成型温度对多孔碳化硅陶瓷的孔隙率、密度、抗弯强度及热震性能均...     

陶瓷-金属复合材料在防弹领域的应用研究

陶瓷-金属复合材料具备高硬度、高强度、高韧性以及低密度的优点,已被广泛应用于防弹领域.介绍了几种陶瓷-金属复合装甲形式及其相应特点,重点论述了陶瓷-金属功能梯度装甲的研究进展,并对其前景和当前的工作重点进行了讨论.     

SiC泡沫／Al双连续相复合材料连续性的研究

运用挤压铸造法制备了SiC泡沫／Al双连续性复合材料，研究了SiC泡沫、复合压力和合金成分对复合材料连续性的影响。结果表明，SiC泡沫陶瓷的加入阻碍了基体合金流动，降低了复合材料的连续性。随着复合压力的增加，复合材料的连续性逐渐增强，当压力为150MPa时，复合材料的连续性最好。随着含硅量的增加，基体合金的热膨胀系数逐渐降低，基体和增强体之间的热膨胀匹配增强，复合材料中残余应力降低，复合材料的连续性增强。     

Al2O3-5 wt% Al composites by ICP sintering of synthesized precursor

Microstructure developments during the milling of Al₂O₃-5wt% Al composite powder in an attritor and subsequent sintering of the precursor by inductively coupled argon plasma are presented. After 4 h of milling the precursor contained tubular ceramic-metal and uniform ceramic regions. With an increase in the milling period the ceramic-metal regions broke into smaller and almost globular regions, and the smaller regions became dispersed in the ceramic regions. After 8 h of milling the composite powder had a stable microstructure and contained 0.25–0.35 m clusters. The sintered composite was > 99.7% dense and its microstructure consisted of ceramic-metal regions which were dispersed in the matrix of a ceramic region. The sizes of ceramic grains in ceramic-metal regions and the ceramic regions were 0.3–2.2 and 0.8–1.8 m, respectively. Many ceramic grains in ceramic-metal regions were separated by 30–100 nm wide metal layers. The microstructure of the ceramic-metal region showed many features of interpenetrating phase composites. The Knoop and Vickers microhardnesses of the composites at 5–10 N loads were 410–450. Under 10 N loads in Knoop and Vickers microhardness tests the crack length was 11±3 and 3 ± 0.5 m, respectively. The crack propogation mechanisms in the indented areas are discussed.     

Experimental and numerical research on high‐temperature thermal insulation performance of lightweight porous ceramic/nanomaterial composite structure

The thermal protection structure of hypersonic vehicles must meet the design requirements of high efficiency and light weight, and its heating surface must also be able to withstand thermal erosion by high‐speed and high‐temperature airflow. In this paper, a light‐weight porous ceramic material and a lightweight nanoscale thermal insulation material with excellent thermal insulation performance are combined to form an integrated thermal protection structure. Experimental study and numerical simulation of the structure's high‐temperature thermal insulation performance are carried out. The experimental results show that a composite sheet made from a 20 mm‐thick lightweight porous ceramic material and a 10 mm‐thick nanomaterial exhibit a temperature drop of 85 % between its back surface and front surface in four thermal environments (1200, 1000, 800 and 600 °C) at 1800 s. This indicates excellent thermal insulation performance of the composite sheet. In addition, the operating temperature limit (<1000 °C) is obtained through high‐temperature thermal performance tests on single‐layer nanomaterial sheets and scanning electron microscopy results. This provides an important basis for determining and optimizing the thickness ratio of the two materials in composite structure.     

碳化锆陶瓷复合材料的制备、显微组织与性能

碳化锆(ZrC)陶瓷复合材料具有熔点高、密度低、耐烧蚀的优点, 在超硬、航天防热、新能源等领域应用前景广阔。本文概述了ZrC金属陶瓷和复相陶瓷、纤维增强ZrC复合材料的制备方法。着重介绍了粉末烧结、先驱体转化、反应浸渗等工艺的应用, 并讨论了不同制备工艺下复合材料显微组织的特点。在总结两类材料力学性能和烧蚀性能的基础上, 分析了各自的影响因素, 并指出ZrC金属陶瓷和复相陶瓷韧性低, 纤维增强ZrC复合材料烧蚀层易剥落的问题。最后总结展望了ZrC陶瓷复合材料相关研究的发展趋势。