检索结果-南通市图书馆

在线全文

cnki会议

学校读者我要写书评

暂无评论

燃烧合成(Ti,W)C的形成过程

稀有金属与硬质合金 2001年第4期29卷 1-6页

作者：李劲风张昭郑子樵徐协文浙江大学化学系浙江杭州310027 中南大学材料科学与工程系湖南长沙410083

研究了W /(Ti+W ) =0 .4 0 ,0 .5 4两种配比的Ti-W -C体系在不同反应条件下的燃烧合成产物相组成及燃烧块断面组织 ;结合燃烧前沿激冷淬熄法 ,分析了其燃烧前沿高温动态反应过程。研究表明 ,体系燃烧过程中存在两种反应模式。熔化 -溶... 详细信息

研究了W /(Ti+W ) =0 .4 0 ,0 .5 4两种配比的Ti-W -C体系在不同反应条件下的燃烧合成产物相组成及燃烧块断面组织 ;结合燃烧前沿激冷淬熄法 ,分析了其燃烧前沿高温动态反应过程。研究表明 ,体系燃烧过程中存在两种反应模式。熔化 -溶解 -析出机制 :燃烧高温使燃烧前沿Ti粉熔化 ,W、C溶解于熔融Ti中 ,而后 (Ti,W)C从Ti-W -C熔体中析出。扩散 -固溶机制 :当燃烧温度不足以使燃烧前沿Ti粉熔化时 ,C沿燃烧过程中形成的Ti颗粒裂纹快速扩散 ,与固态Ti核反应形成TiC ;同时通过C的扩散 ,W与C反应先形成W2 C ,然后转变成WC ;而后WC固溶至TiC中 ,形成 (Ti,W)C。

关键词：燃烧合成熔化-溶解-析出机制扩散-固溶机制碳化钛碳化钨石实合金

SYNTHESIS OF INTERMETALLICS BY MECHANICAL ALLOYING

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1995年第Z1期8卷 441-446页

作者： F. H.(Sam) Froes C. Suryanarayana and D. Mukhopadhyay (Institute for Materials and Advanced Processes (IMAP), university of Idaho,Moscow, ID 83.44-3.26, USA)C-G. Li(BlM, P.O. Box 81 , Beijing, 100095, P.R. china)K. Brand(On leave from Institut fur Werkst Univ of Idaho Moscow United States

Mechanical alloying (MA), a solid-state powder processing method, is a 'far from equilibrium' synthesis technique which allows development of novel crystal structures and microstructures, leading to enhanced physical and mechanical properties. The ability to synthesize a variety of alloy phases including supersaturated solid solutions, nanocrystalline structures, amorphous phases and intermetallic compounds themselves is discussed. No extension of solubility using MA has been observed in the intermetallics studied. Nanostructured grains were observed in all compositions. Long time milling generally resulted in amorphous phase formation in large part because of the increase in grain boundary energy/mole with reduced grain size; good agreement with the Miedema model for amorphization was obtained in the Al-Fe system. Generally an anneal was required to form the intermetallic after MA; however,intermetallics with a large negative enthalpy of formation were detected in the MA condition. A study of the hot isostatic pressing of γ-TiAl powders produced by MA demonstrated that full density can be achieved at least 400℃ below the normal temperature required for conventional powder, that is 725℃ or below. Nanometered sized grains (≤100nm)were observed after HIP'ing up to 850℃.

关键词： Intermetallics mechanical alloying hot isostatic pressing

IN SITU SYNTHESIS OF CATALYSTS WITH HIGH Ni DISPERSION AND THEIR DECHLORINAION ACTIVITY TO CHLORIBENZENE

在线全文

学校读者我要写书评

暂无评论

IN SITU SYNTHESIS OF CATALYSTS WITH HIGH Ni DISPERSION AND T...

Ⅻ International Symposium on Small Particles and Inorganic Clusters

作者： MAO Shu-Bing LI Dian-Qing Evans D.G DUAN XueKey laboratory of Science and Technology of Controllable Chemical Reactions Ministry of Education Beijing university of Chemical Technology Beijing 100029

＜正＞ Conventionally, supported metal catalysts are prepared by impregnating supports in aqueous solutions containing active metals. The properties of catalysts prepared by this method are not fully reproducible because of high surface tension of water. The most evident fact is to lead to inhomogeneity in distribution of the metal supported. Moreover, this inhomogeneity will be usually enhanced during the calcination process at high temperature.

关键词： Ni/γ-AlO3 catalysts hydrodechlorination LDHs in-situ synthesis

是否存在稳定的高原子序数原子?——狄拉克材料中的原子塌缩现象

在线全文

cnki会议

学校读者我要写书评

暂无评论

科学通报 2018年第7期63卷 601-605页

作者：刘海文王慧超王健北京师范大学物理学系高等量子研究中心北京100875 北京大学物理学院量子材料科学中心北京100871 量子物质科学协同创新中心北京100871

相对论量子力学预言当原子序数超过某一特定值时,原子会发生塌缩现象.然而这一重要理论预言仍未得到实验的直接证实.狄拉克材料中的准粒子满足相对论性方程,并且体系的精细结构常数远大于真空中取值,因而可以用来探究原子塌缩现象.最近... 详细信息

相对论量子力学预言当原子序数超过某一特定值时,原子会发生塌缩现象.然而这一重要理论预言仍未得到实验的直接证实.狄拉克材料中的准粒子满足相对论性方程,并且体系的精细结构常数远大于真空中取值,因而可以用来探究原子塌缩现象.最近在狄拉克半金属中发现一种全新的以磁场对数为周期的磁阻振荡,表明体系中准粒子存在原子塌缩现象和伴随出现的离散标度不变性.

关键词：原子塌缩离散标度不变性狄拉克半金属磁阻振荡

Study on Kinetics of Crystallization of Nanophase in Glass-Ceramics as Magnetic Disk Substrate

在线全文

学校读者我要写书评

暂无评论

Study on Kinetics of Crystallization of Nanophase in Glass-C...

Ⅻ International Symposium on Small Particles and Inorganic Clusters

作者： Sheng yu Jiang Jian cheng Zhang Wang Hua Yue Shen Xiao’an Zhou College of Material Science and Engineering, Shanghai university, Shanghai 201800, P.R.china

Glass-ceramics with nanophase have so excellent properties such as high mechanical strength, high elastic modulus, good surface roughness that the materials can be widely applied in magnetic storage substrate, microelectronics, biologic materials and so *** this paper, a multi-component system of Li2O-Al2O3.SiO2 glass-ceramics with ZrO2 and P2O5 as the nucleation agent was prepared. In order to enhance the properties of

关键词：

Benzene Clusters Dissociation in the Intense Laser Field

在线全文

cnki会议

学校读者我要写书评

暂无评论

Benzene Clusters Dissociation in the Intense Laser Field

Ⅻ International Symposium on Small Particles and Inorganic Clusters

作者： Hongtao Liu Shutao Sun Zichao Tangstate key laboratory of Molecular Reaction Dynamics Institute of Chemistry Chinese Academy of Sciences Beijing 100080

＜正＞ Field ionization of benzene clusters in the intense laser field is experimentally investigated using a femtosecond laser and reflection time of flight mass spectrometer. The dissociation products in intense laser field are obviously different from the products that benzene clusters were interacted by nanosecond laser. The femtosecond laser pulse width is 100 fs at λ=800

关键词：

在线全文

cnki会议

学校读者我要写书评

暂无评论

规整、均一纳米水滑石晶体的水热合成与表征

化学学报 2006年第22期64卷 2231-2234页

作者：郑建华田熙科俞开潮王龙艳杨超何明中中国地质大学材料科学和化学工程学院武汉430074 华中科技大学化学系武汉430074

采用一种简便的新方法,以Mg2+/Al3./CO23.摩尔比为6∶2∶1的比例在水热条件下合成了[Mg-Al-CO3.水滑石.获得的水滑石样品用XRD,FE-SEM,TEM,HRTEM,TG-DSC进行了物相、晶体形貌结构和热分析.用动态光散射原理分析了粒度分布,考察了水热合... 详细信息

采用一种简便的新方法,以Mg2+/Al3./CO23.摩尔比为6∶2∶1的比例在水热条件下合成了[Mg-Al-CO3.水滑石.获得的水滑石样品用XRD,FE-SEM,TEM,HRTEM,TG-DSC进行了物相、晶体形貌结构和热分析.用动态光散射原理分析了粒度分布,考察了水热合成的主要条件水热温度和时间对水滑石晶体尺寸及粒度分布的影响.结果表明,本法合成的水滑石具有均一、规整的六边形片状晶体形貌,片状晶体直径在3.0nm左右,片的厚度约20nm,纯水滑石相,粒度分布在80～420nm.水热温度和时间主要影响片状晶体的直径,而对晶体形貌影响不大;延长反应时间,升高水热温度可使六边形晶片长大.

关键词：水滑石水热合成晶体形貌粒度