共查询到20条相似文献,搜索用时 108 毫秒
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以3TiO2 3C (4 x)Al为反应体系,用电场激发燃烧合成技术并使用合成中形成的液态Al对产物的渗透作用,制备出致密度为92.5%的Al2O3-TiC-Al复合材料,采用燃烧波峰淬熄法研究了原位合成Al2O3-TiC-Al复合材料的结构形成机理.结果表明:电场提供的焦耳效应可提高体系的绝热燃烧温度,从而可突破该体系只能在x<10 mol下发生SHS反应的热力学限制;在Al2O3-TiC-Al复合材料动力学过程中,首先Al粉熔融,进而加速与TiO2的反应生成Al2O3;然后Al与TiO2反应还原出Ti并与C反应生成TiC;液态Al的渗透将Al2O3和TiC颗粒粘结起来,形成致密的复合材料组织. 相似文献
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以天然钛铁矿为主要原料,采用燃烧合成技术制备了TiC-Al2O3/Fe3Al金属间化合物/陶瓷基复合材料.研究了预热时间和热处理对燃烧合成过程及产物的影响.研究结果表明:随着预热时间的延长,燃烧温度和燃烧波速率都增加,产物晶胞参数增大,合成更为完全,无序固溶相进行有序化转变的程度增大.当预热5min时,Fe3Al有序金属间化合物的量明显高于无序固溶相,但继续延长预热时间很难将无序相消除;在750℃下进行热处理,可以制备出以Fe3Al金属间化合物为主要成分的复合粉体. 相似文献
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自蔓延高温合成Al2O3-TiC/Fe-Al复合材料的研究 总被引:6,自引:1,他引:5
以天然钛铁矿为主要原料,采用SHS技术,通过铝热、碳热还原法合成了Al2O3-TiC/Fe-Al 金属间化合物/陶瓷基复合材料.研究了SHS合成过程中制坯压力、预热时间、稀释剂和碳源对SHS合成过程的影响.研究结果表明:制坯压力在40MPa时,燃烧温度与燃烧波速率出现最大值;随着预热时间的延长,燃烧温度和燃烧波速率都增加,产物中TiC和Al2O3晶体的晶格间距增大,合成更为完全,产物中只包含有TiC相、Al2O3相、Fe-Al相和α-Fe固溶相;稀释剂会降低燃烧温度和燃烧波速率,同时使产物的密度降低,且不利于合成产物的形成;与炭黑相比用石墨做碳源时,燃烧温度、燃烧波速率以及产物的密度都高,反映了碳源结构差异对燃烧合成的影响. 相似文献
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利用钛铁矿铝热碳热原位还原技术成功制备了Al2O3-TiC增强铁基复合材料。通过XRD,SEM和力学性能检测方法分析了钛铁矿原位合成和添加合成两种方式对Al2O3-TiC增强铁基复合材料的组织和力学性能的影响。结果表明:利用钛铁矿合成的铁基复合材料的增强相为Al2O3,MgAl2O4,TiC和Fe相,添加合成过程中会发生一些硬质相TiC被氧化的现象。钛铁矿原位合成Al2O3-TiC增强铁基复合材料的基体组织呈粗大的块条状分布;添加合成的复合材料的铁基体以块状均匀分布。制备的Al2O3-TiC增强铁基复合材料的性能比较优良。材料的最佳综合力学性能为抗弯强度937MPa,维氏硬度532。 相似文献
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回顾了国内外在定向金属氧化法制备Al/Al2O3陶瓷基复合材料方面的研究成果,详细讨论了合金成分、外敷剂、温度和气氛以及预形体对其反应机理和显微结构的影响,指出了今后定向金属氧化法制备Al/Al2O3陶瓷材料的研究重点和发展方向. 相似文献
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晶内/晶间复合型Al2O3/Ni纳米金属陶瓷显微结构和力学性能的研究 总被引:2,自引:0,他引:2
采用非均相沉淀法和热压工艺制备了Al2O3/Ni纳米金属陶瓷。在1450℃热压γ-Al2O3/Ni复合粉体得到相对密度>985的金属陶瓷。结果表明,Ni颗粒均匀分布在基体中,其中<100nm的Ni颗粒位于Al2O3晶内,100-300nm的分布在晶界,形成了晶内/晶界复合型纳米金属陶瓷。同单相Al2O3相比,Al2O3/Ni金属陶瓷的三点抗弯强度和断裂韧性分别增加了26%和795。分析了纳米金属陶瓷的增强增韧机制。 相似文献
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莫来石对氧化铝基陶瓷型芯的高温抗变形能力的影响 总被引:1,自引:0,他引:1
研究了在不同状态下,氧化铝基陶瓷型芯中莫来石的含量及其微观结构对氧化铝基陶瓷型芯高温抗变形性能的影响.结果表明,氧化铝基陶瓷型芯具有优良的热强性能归因于高温下莫来石柱状晶群的存在. 相似文献
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为了进一步提高金属陶瓷的力学性能及其刀具的高速切削性能, 研究了纳米增强金属陶瓷的显微组织特征和热冲击性能。扫描电镜和透射电镜分析表明: 组织中陶瓷相呈现典型的芯2壳结构特征; 芯为TiC 或Ti (C ,N) , 而壳则为( Ti ,Mo ,W) (C ,N) 固溶体。纳米增强金属陶瓷机制为细晶强化、弥散强化和固溶强化。热冲击实验表明: 随着热循环的进行, 材料中孔洞的数量、孔洞的尺寸以及微裂纹的尺寸随之增大; 同时, 热循环过程中出现的表面氧化、裂纹长大、偏转以及桥接现象也很显著。与常规Ti (C ,N) 金属陶瓷相比, 纳米增强金属陶瓷的抗热冲击性能明显提高。 相似文献
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Maksim Kireitseu 《Particulate Science and Technology》2002,20(3):209-223
Fracture of Al-Al 2 O 3 -diamond-containing composite coating was investigated using rheological models for principal Hertzian contact of a sphere and a plate. The crystallographic and morphologic texture was characterized and the fracture resistance was measured using fracture mechanics. A rheological model of the composite coating was proposed and confirmed by in situ experiments. Examination of the composite coating showed a hardness value of 25 GPa (about 25% higher than for an alumina-based layer) and fracture resistance (about 50% higher than for a single oxide ceramic layer) as compared to prior alumina-based coatings on a soft substrate. Experiments revealed ultimate stresses and stress-strain modes of the coating. Diamond nanoparticles improved fracture resistance of an alumina-based layer. It is also thought that the composite coatings will have higher thermal conductivity and thermal shock resistance than alumina-based layers. Such physical characteristics suggest a number of possible commercial applications for the composite coatings, particularly for wear-resistant and related applications. The higher hardness and toughness of the coatings make them very attractive as substitutes for alumina-based and other ceramic-based composite coatings in these applications.
composite rheology fracture stress indentation diamonds 相似文献
composite rheology fracture stress indentation diamonds 相似文献
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含氮金属陶瓷的发展现状及展望 总被引:7,自引:2,他引:5
综述了含氮金属陶瓷的最新进展,着重介绍了氮化钛等硬质相的基本性质,含氮金属陶瓷的显微结构特征,以及碳氮比、粘接相体积分数和添加不同碳化物对其机械性能的影响。 相似文献
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MAKSIM KIREITSEU 《Particulate Science and Technology》2013,31(3):209-223
Fracture of Al-Al 2 O 3 -diamond-containing composite coating was investigated using rheological models for principal Hertzian contact of a sphere and a plate. The crystallographic and morphologic texture was characterized and the fracture resistance was measured using fracture mechanics. A rheological model of the composite coating was proposed and confirmed by in situ experiments. Examination of the composite coating showed a hardness value of 25 GPa (about 25% higher than for an alumina-based layer) and fracture resistance (about 50% higher than for a single oxide ceramic layer) as compared to prior alumina-based coatings on a soft substrate. Experiments revealed ultimate stresses and stress-strain modes of the coating. Diamond nanoparticles improved fracture resistance of an alumina-based layer. It is also thought that the composite coatings will have higher thermal conductivity and thermal shock resistance than alumina-based layers. Such physical characteristics suggest a number of possible commercial applications for the composite coatings, particularly for wear-resistant and related applications. The higher hardness and toughness of the coatings make them very attractive as substitutes for alumina-based and other ceramic-based composite coatings in these applications. composite rheology fracture stress indentation diamonds 相似文献
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Ti(C,N)基金属陶瓷的研究进展 总被引:1,自引:0,他引:1
介绍了Ti(C,N)基金属陶瓷的晶体结构和高温力学性能,综述了其主要制备方法和研究进展,详细地分析了其冶金机理和相结构特点,并讨论了环型相的形成机理及缺点,最后指出了Ti(C,N)基金属陶瓷研究方向和提高其性能的基本途径,并认为系统考虑其相平衡、粉末冶金机制和加工工艺是制备性能优良的Ti(C,N)基金属陶瓷刀具和涂层的关键. 相似文献
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The preparation of thin films of cermets of gold in magnesium fluoride and the ellipsometric determination of the optical constants of the materials of the films are described. The results for materials of two compositions are compared with predictions based on the Maxwell Garnett expression for the complex refractive index of cermets in terms of the refractive indices of the constituents. It is shown that reasonable agreement between experimentally determined and theoretical values of the refractive indices of the cermets can be approached only if the restriction of the mean free paths of the conduction electrons in the gold particles is taken into account. 相似文献
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The ferromagnetic Al2O3-based cermets with different ratios of Co and Co–50Ni alloys were successfully prepared by combustion synthesis in thermal
explosion (TE) mode. The reaction process, microstructure, and magnetic property of cermets were investigated. The relative
density of cermets can be over 95% via uniaxial loading at the time of ignition when the cermets are hot and ductile. In Al2O3–Co cermets, β-Co and α-Co co-exist at room temperature with average size of less than 10 μm and disperse homogeneously in
the matrix, while in Al2O3–(Co–50Ni) cermets, the network-like Co–50Ni alloy can infiltrate into the boundary gaps of Al2O3 particles. The ferromagnetic Co and Co–50Ni alloys are responsible of the magnetic properties of Al2O3-based cermets. The saturation magnetization strongly depends on the magnetic characteristics and ratios of ferromagnetic
phases. Al2O3–(Co–50Ni) cermets have soft magnetic properties with high magnetic susceptibility and low coercive force. 相似文献