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通过自蔓延高温合成结合准热等静压法(SHS/PH IP) 制备出了致密的TiC2Al2O3-20Fe 金属陶瓷。研究了延迟时间、高压持续时间、压力等工艺参数对金属陶瓷密实度的影响, 分析了金属陶瓷的相组成、微观组织及性能。结果表明, 燃烧合成过程中气体的排放和液相的存在是合成密实材料的关键, 通过优化工艺合成了密实度为97. 7% 的TiC2Al2O3-20Fe 金属陶瓷。金属陶瓷由TiC、Al2O3 和Fe 粘结相组成。粘结相Fe 与Al2O3 之间界面光滑,Fe 与T iC 之间有一较薄扩散层。TiC2Al2O3-20Fe 金属陶瓷的抗弯强度和抗压强度分别为890M Pa 和18. 4 GPa。 相似文献
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研究了反应物起始条件对非化学计量碳化钛SHS过程燃烧动力学的影响。用燃烧波淬火法分析了燃烧产物组织形成过程,并计算了SHS过程的激活能。 研究SHS—准热等静压工艺表明,制备非化学计量碳化钛基金属陶瓷时,存在一有利于致密化的最佳施压滞后时间。增大外加压力有利于提高最终产物密度,直到压力大于160MPa后产物密度不再增大,施加压力的保持时间超过1.5min后,延长时间亦不能增加最终产物密度。 在C/Ti=0.42~0.50范围内,用SHS—准热等静压工艺制备了致密化的非化学计量碳化钛基金属陶瓷。金属陶瓷经800℃、0.5h处理后,其中的非化学计量碳化钛相发生有序化转变,金属陶瓷的抗弯强度增大。 根据材料设计知识,添加Ni、TaC、Mo有效地细化了金属陶瓷晶粒,提高了金属陶瓷性能。并且添加Mo使粘结相由α-Ti(hcp)转化为β-Ti(bcc),提高粘结相变形能力。在C/Ti=0.45时,同时添加7wt%的Mo和4wt%TaC的复合作用使金属陶瓷抗弯强度达884.0MPa,硬度HRA87.3。 自蔓延高温合成的非化学计量碳化钛基金属陶瓷,具有较好的红硬性和优良的耐腐蚀性能。 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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以Al粉、TiO_2粉、C粉和稀土La_2O_3粉为原料,利用放热弥散法原位合成稀土La_2O_3质量分数为0.3%的AlTiO_2-C晶粒细化剂,压制压力分别为80,85,88,90kN和92kN,研究不同压力制备的细化剂对ZL101合金细化效果的影响。采用X射线衍射仪、扫描电镜及能谱仪研究压制压力对Al-TiO_2-C细化剂相组成和显微组织的影响。利用MATLAB软件提取特征值评价Al-TiO_2-C细化剂对ZL101合金的细化能力。结果表明:压制压力为90kN时,Al-TiO_2-C细化剂组织中Al_3Ti呈圆块状数量明显增多,尺寸均匀,形核颗粒TiC和Al_2O_3数量有所增多,此种组织的细化剂对ZL101合金具有最好的细化效果。 相似文献
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以Al-SiO_2为反应体系,通过烧结反应原位合成了(Al_2O_3+Si)_p/Al复合材料。研究了第二相含量、烧结时间以及热锻压等工艺对(Al_2O_3+Si)_p/Al复合材料的第二相形貌、尺寸及分布的影响,探讨了原位合成(Al_2O_3+Si)_p/Al复合材料的生成机制。研究表明,Si相含量随着第二相含量的增多而增多且与Al和Al_2O_3相界限相对明显;随着烧结时间的延长,Si相面积相对减小,Al_2O_3相的数量相对增加;锻压后,Si相和Al_2O_3分布更加均匀且尺寸减小。复合材料在液相烧结的过程中,高温下的液相粘性流动以及在原位反应时发生的颗粒重排与固相的溶解和沉淀对材料的致密化产生了较大的作用,当烧结温度达到1000℃时,Al_2O_3颗粒数量、分布情况都得到明显地改善。 相似文献
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利用低放热Al-TiO2反应体系部分取代高放热Al-CoO反应体系,并加入适量的稀释剂Al2O3吸收反应热量,通过热爆燃烧合成结合致密化工艺制备了铁磁性Co(Ti)-Al2O3金属陶瓷。研究表明,Co(Ti)-Al2O3金属陶瓷中随着Al-TiO2体系的增加,燃烧反应温度降低,金属相尺寸减小,分布更均匀,同时在金属相与基体之间形成过渡区域,提高了界面结合。Co(Ti)-Al2O3复合材料的饱和磁化强度随着金属Co含量增加而增加,最高可达到37.2849Am2/kg,而矫顽力在3997.6~5615.4A/m范围内变化,介于软磁体和硬磁体之间。 相似文献
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A. K. Chaubey B. K. Mishra N. K. Mukhopadhyay P. S. Mukherjee 《Journal of Materials Science》2010,45(6):1507-1513
Magnesium reinforced in situ TiC particulates was successfully synthesized by utilizing the self-propagating high temperature
synthesis (SHS) process. The result showed that preform temperature and compact density have effects on the SHS reaction.
It is observed that when the compact density was below 68% of the theoretical density, no SHS reaction occurred. However,
with an increase in density from 68 to 72%, the successful thermal explosion reaction was observed in the Mg melt. Besides
this, the effect of preheat temperature on the fabrication of Mg/TiC composite was extensively studied and found that the
preheat temperature below 300 °C failed to give rise to SHS reaction. However, the preheat temperature of 450, 500, and 550 °C
favors the reaction inside the liquid melt, but the temperature of 600 °C leads to the ignition reaction in the preheating
furnace itself. SEM and EDX study confirms fine distribution of TiC in the matrix. 相似文献
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K. L. Stepanov L. K. Stanchits Yu. A. Stankevich 《Journal of Engineering Physics and Thermophysics》2011,84(1):179-206
The hydrodynamic and radiation processes accompanying explosions of chemical explosives and fuel-air mixtures have been considered.
Computer modeling of the radiation from a fire ball of explosion and a flame of diffusion combustion of a hydrocarbon fuel
has been performed. The dependences of the heat flux density from the region occupied by explosion and combustion products
on its temperature and geometric characteristics have been determined. Thermal load distributions on targets of different
orientations in the vicinity of the energy release zone have been obtained. A comparison of the thermal parameters on radiation
detectors with the criteria of thermal affection of people and ignition of combustible materials has been made. 相似文献
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自蔓延高温合成油气管的耐蚀性研究进展 总被引:2,自引:0,他引:2
介绍了自蔓延高温合成陶瓷内衬复合管的特点和制备原理以及提高复合管内衬陶瓷层耐蚀性的途径 ,同时还介绍了自蔓延高温合成不锈钢内衬复合管工艺。自蔓延高温合成不锈钢内衬复合管的耐蚀性比普通钢管高 10倍以上。展望了自蔓延高温合成内衬复合管在油气管上的应用前景 相似文献
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放射性废物的SHS固化处理研究及应用 总被引:2,自引:1,他引:1
采用自蔓延高温合成技术(SHS)固化处理放射性废物是固化方法新的研究方向。分析探讨了SHS固化处理方法的固化机理、研究现状及固化特点。SHS固化具有工艺简单、能量利用效率高、处理过程快速、成本低廉等优点,可针对不同类型的放射性废物选择合适的反应体系,进行产物设计,可直接应用到废物处置点或实现废物就地处置。介绍了近期笔者采用铝热剂自蔓延高温合成固化处理爆炸过程产生的有毒物质和受锕系核素污染的砂土及时两种形态的核废物的模拟固化实验研究。 相似文献
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Some properties of titanium diboride (TiB2) obtained by explosive mechanochemical synthesis and self-propagated high-temperature synthesis (SHS) have been investigated. The properties of zirconium diboride (ZrB2) obtained by SHS have also been studied. There is a general opinion that explosive mechanochemical synthesis proceeds by a SHS mechanism. For that reason, it is of interest to compare the properties of a product synthesized from the same reagents, by both mechanochemical synthesis and SHS. In order to elucidate the peculiarities of mechanochemical synthesis, the changes in shape and size of the titanium particles occurring during their mechanical treatment up to the moment of synthesis have been examined. Titanium and zirconium powders with particles differing drastically in shape and size have been used for the synthesis of TiB2 and ZrB2 by SHS. It has been shown that irrespective of the difference in properties of the reagents, the products obtained have some common properties characteristic of the synthesis method and important with respect to the practical applications of the borides of titanium and zirconium. 相似文献
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在材料的自蔓延高温合成(SHS)过程中,反应物与产物之间,各种结构层次(宏观、微观、晶体结构等)上的转变过程—结构宏观动力学,对材料制备具有决定意义。本文分别在宏观结构和微观结构两个层次上研究了Al-TiO_2自蔓延高温合成系统的结构宏观动力学。结果表明:在宏观结构上,随着样品尺寸加大,如工艺控制不当会出现三种主要的宏观结构缺陷:气孔增加,偏析加剧、宏观裂纹。材料的显微结构,是由燃烧波内一种非均匀网络状过渡组织转变而来的。 相似文献
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Inder Pal Singh Kapoor Manisha Kapoor Gurdip Singh Udai P. Singh Nidhi Goel 《Journal of hazardous materials》2010,173(1-3):173-180
Nitrate and perchlorate salts of 2,4,6-trimethylaniline have been prepared and characterized by X-ray crystallography and gravimetric analyses. Their thermal decomposition has been studied by TG, TG–DSC and ignition/explosion delays. It has been observed that proton transfer from substituted anilinium ion to nitrate and perchlorate ion regenerate amine, HNO3 and HClO4 in condensed phase at higher temperature, where oxidation–reduction between amine and acids leads to ignition and explosion. The kinetics of thermal decomposition was evaluated by applying model fitting as well as isoconversional methods. The values of calculated activation energy of nitrate and perchlorate salts are 77.9 and 118.2 kJ mol?1 respectively. The possible pathways of thermolysis of these salts have also been proposed. 相似文献
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R. Sh. Gainutdinov 《Journal of Engineering Physics and Thermophysics》2006,79(4):741-745
A conjugated problem of heat conduction for two hollow cylinders that are in close contact, with one consisting of a reagent,
has been solved analytically. The problem has been solved by the backward method under boundary conditions of the first kind.
The critical conditions of thermal explosion were investigated as functions of the parameters of a reagent and of an inert
body. An engineering method for determining the critical conditions of a thermal explosion is suggested.
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Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 4, pp. 110–113, July–August, 2006. 相似文献