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自蔓延高温合成Ti3AlC2 和Ti2AlC及其反应机理研究 总被引:17,自引:1,他引:17
以Ti,Al和C的粉体混合物为原料,在纯氩气气氛,25MPa压力,1600℃保温4h条件下,自蔓延高温合成了Ti3AlC2和Ti2AlCT,利用X射线衍射分析(XRD)和扫描电镜(SEM)等手段对反应产物进行了研究,提出了自蔓延高温合成Ti3AlC2和Ti2AlC应具备的条件,并探讨了Ti,Al和C自蔓延高温合成Ti3AlC2和Ti2AlC的反应机理,结果表明,Ti3AlC2和Ti2AlC能够由Ti,Al和C元素经高温自蔓延合成反应来制备,其制备的必要条件是需要极快的加热速率以防止铝熔化并且改变钛的转移路线,Ti3AlC和Ti2AlC综合了金属材料和陶瓷材料的优点,成功的应用自蔓延高温方法合成Ti2AlC2和TiAlC必将成为该类材料纯块体的合成和制备提供好的原料,从而这类材料的实际应用将起到极大的推动作用。 相似文献
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以TiC、Ti和Al粉为原材料,采用冷压预成型-热压辅助工艺原位制备Ti3 AlC2陶瓷.借助反应吉布斯自由能分析TiC-Ti-Al体系的合成机制,采用XRD和SEM分析工艺因素如升温速率、Al含量、烧结温度和压坯尺寸对原位合成Ti3 AlC2陶瓷的影响.结果表明,通过调控工艺,成功合成了高纯度Ti3 AlC2陶瓷,Ti3 AlC2具有典型的层状结构.该反应体系的最佳升温速率为:1000℃之前,20℃/min; 1000℃之后,10℃/min.用纳米TiC粉替代微米TiC粉,烧结温度由1450℃降至1350℃,且Ti3 AlC2的合成纯度更高.当采用大尺寸压坯时,发生了“热爆”现象,非平衡相较多,Ti3 AlC2的生成含量较低,且样品开裂严重.Ti3 AlC2的合成过程为:Ti与Al反应生成TiAl金属间化合物,接着TiAl与TiC反应生成Ti3AlC2. 相似文献
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Ti_3AlC_2陶瓷的热压合成 总被引:1,自引:0,他引:1
以TiC-Ti-Al为反应体系,采用原位热压技术制备Ti3AlC2陶瓷。借助XRD分析相组成,并对实验现象进行分析。结果表明,TiC的加入,避免了Ti和C粉之间强烈的放热反应。通过降低初始压坯尺寸抑制了"热爆行为",有利于合成高纯Ti3AlC2。用大压坯时,"热爆行为"明显,产物由Ti3AlC2、TiC和Ti3Al相组成,Ti3AlC2含量少;用小压坯时,未发生"热爆行为",产物由Ti3AlC2和TiC相组成,Ti3AlC2相含量较高。 相似文献
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分别以粉末钛粉、硅粉、石墨和钛粉、碳化硅、石墨为原料,采用热压烧结法制备了Ti3SiC2材料,借助XRD和SEM手段研究了原料体系和烧成温度对试样相组成、致密化程度和显微结构的影响,并分析了反应烧结机理。结果表明:(1)随着温度的升高,钛粉-硅粉-石墨体系较钛粉-碳化硅-石墨体系合成出的Ti3SiC2块体材料纯度更高;(2)钛粉-硅粉-石墨体系在烧结温度低于1300℃时,主要以Ti5Si3、TiC和残余的硅粉、石墨反应生成Ti3SiC2,在烧结温度为1300~1600℃时,主要以形成的液相Ti-Si(L)与TiC反应生成了Ti3SiC2;钛粉-碳化硅-石墨体系在1485℃液相出现之后,颗粒经历重排和溶解再析出的过程,在液相中生成Ti3SiC2。 相似文献
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Songlan Yang Zheng Ming Sun Hitoshi Hashimoto Toshihiko Abe 《Journal of the European Ceramic Society》2003,23(16):3147-3152
In this study, free 2Ti/2Si/3TiC powder mixture was heated at high temperatures in vacuum, in order to reveal the possibility for the synthesis of high Ti3SiC2 content powder. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the evaluation of phase identities and the morphology of the powder after different treatments. Results showed that almost single phase Ti3SiC2 powder (99.3 wt.%) can be synthesized by heat treatment with free 2Ti/2Si/3TiC powders in vacuum at 1210°C for about 3 h. The nucleation and growth of Ti3SiC2 within TiC particles was observed. The typical appearance of the formed Ti3SiC2 is equiaxed with particle size of 2–4 μm. Effects of temperature and heating time on the morphology and the particle sizes of the synthesized Ti3SiC2 powders are not obvious. 相似文献
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Near-fully dense Ti3Si(Al)C2/Ti5Si3 composites were synthesized by in situ hot pressing/solid–liquid reaction process under a pressure of 30 MPa in a flowing Ar atmosphere at 1580 °C for 60 min. Compared to monolithic Ti3Si(Al)C2, Ti3Si(Al)C2/Ti5Si3 composites exhibit higher hardness and improved wear resistance, but a slight loss in flexural strength (about 26% lower than Ti3Si(Al)C2 matrix). In addition, Ti3Si(Al)C2/Ti5Si3 composites maintain a high fracture toughness (KIC = 5.69–6.79 MPa m1/2). The Ti3Si(Al)C2/30 vol.%Ti5Si3 composite shows the highest Vickers hardness (68% higher than that of Ti3Si(Al)C2) and best wear resistance (the wear resistance increases by 2 orders of magnitude). The improved properties are mainly ascribed to the contribution of hard Ti5Si3 particles, and the strength degradation is mainly due to the lower Young's modulus and strength of Ti5Si3. 相似文献
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Fanyu Kong Xiaodong He Qianqian Liu Xinxin Qi Yongting Zheng Rongguo Wang Yuelei Bai 《Ceramics International》2018,44(10):11591-11596
The presented work compared the etching behavior between combustion synthesized Ti3AlC2 (SHS-Ti3AlC2) and pressureless synthesized Ti3AlC2 (PLS-Ti3AlC2). Because the former had a more compact structure, it was harder to be etched than PLS-Ti3AlC2 under the same conditions. When served as anode material for Li-ion batteries, SHS-Ti3C2 showed much lower capacity than PLS-Ti3C2 at 1?C (52.7 and 87.4?mAh?g?1, respectively) due to the smaller d-spacing. Furthermore, Potentiostatic Intermittent Titration Technique (PITT) was used to determine the Li-ion chemical diffusion coefficient () of Ti3C2 in the range of 10?10 ??10?9 cm2 s?1, indicating that Ti3C2 could exhibit an excellent diffusion mobility for Li-ion. 相似文献
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Pressureless sintering in vacuum was applied to synthesize Ti3SiC2 from elemental powders of Ti, Si and C. Based on the phase compositions and purities of the products obtained by X-ray diffraction, the elemental powders composition and sintering condition were optimized. It was found that the sample sintered at 1450 °C for 240 min from a mixture of 3Ti/1.75Si/2C (molar ratio) contained Ti3SiC2 with the volume fraction as high as 93%. It was proposed that loss of Si through gaseous vaporization and contamination of C might be the main obstacles against obtaining high-purity material by this way. 相似文献
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The effect of Al2O3 on mechanical properties of Ti3SiC2/Al2O3 composite fabricated by SPS was studied systematically. The results show that the hardness of the Ti3SiC2/Al2O3 composite can reach 10.28 GPa, 50% higher than that of pure Ti3SiC2. However, slight decrease in the other mechanical properties was observed with Al2O3 addition higher than 5–10 vol.%, which is believed to be due to the agglomeration of Al2O3 in the composite. 相似文献
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以三元碳化物陶瓷Ti_3AlC_2为原料,在500°C~1000°C温度范围内氯化制备具有纳米孔结构的碳化物衍生碳(Ti_3AlC_2-CDC)。高温氯化制备得到的Ti_3AlC_2-CDC由无定形碳和石墨组成。氯化温度越高,石墨化程度越明显,石墨有序度越高。Ti_3AlC_2-CDC的结构与前驱体Ti_3AlC_2的层状结构保持一致。但随着温度升高,Ti_3AlC_2-CDC会逐渐裂解为单片层或多片层。采用N2吸附技术研究了700°C、800°C和1000°C下制备的Ti_3AlC_2-CDC的孔隙结构特征,通过分析试样的吸附等温线特征和孔径分布探讨了温度对CDC孔结构的影响。 相似文献
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Porous Ti3AlC2 ceramics were fabricated by reactive synthesis. The process of fabrication involved five steps: (i) the pyrolysis of stearic acid at 450 °C; (ii) the decomposition of TiH2 at 700 °C, which leads to the conversion of TiH2 to Ti; (iii) the solid–liquid chemical reaction of solid Ti and molten Al at 800–1000 °C, which converts the mixture to Ti–Al compounds; (iv) the newly synthesized Ti–Al compounds that react with surplus Ti and graphite to form ternary carbides and TiC at 1100–1200 °C; and (v) reactive synthesized ternary carbides and TiC that yield porous Ti3AlC2 at 1300 °C. 相似文献
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Yongqiang Tan Sigong Li Xiaochun Han Jiaxiang Xue Tong Liu Xiaosong Zhou Shuming Peng Haibin Zhang 《Ceramics International》2019,45(5):5448-5453
TiO2 was selected as effective sintering aid for pressureless sintering of Ti3AlC2 ceramics in this study. The addition of only 5?wt% TiO2 largely promotes the densification and nearly dense Ti3AlC2 ceramic was obtained by pressureless sintering at 1500?°C. Significant strengthening and toughening effects were observed with the addition of TiO2. High Vickers hardness, flexural strength and fracture toughness of 3.22?GPa, 298?MPa and 6.2?MPa?m?1/2, respectively, were achieved in specimen pressureless sintered with 10?wt% TiO2. Additionally, the addition of 5?wt% TiO2 had no deleterious effect on the excellent oxidation resistance of Ti3AlC2 ceramic under 1200?°C water vapor atmosphere, while addition of 10?wt% TiO2 accelerates the oxidation rate by two orders of degree. 相似文献