黄爱华
,
金鸣林
,
李和兴
,
房永征
材料导报
试验是以2种含不同QI的煤沥青为原料,采用变径反应管进行热转化反应制备有序性中间相的研究.试验采用偏光显微镜和扫描电镜(SEM)观察了原料各反应阶段的微观结构,考察了QI对热转化过程中中间相有序生长的影响,分析了热转化过程中软化点及族组分的变化.结果表明:少量的喹啉不溶物含量不会阻碍中间相有序的发展.高QI(2.03%)原料易生成镶嵌结构的中间相体,高温处理后样品呈轴状、短纤维、层片松散的石墨化焦结构;含低QI(0.11%)的原料能生成较好的、大区域的中间相体,域结构的中间相体在外力导向和内部裂解气流的作用下容易生成有序的半焦,高温处理后呈大区域、片层紧密、有序性强的细纤维焦结构.同时研究发现,在热转化过程中可通过测定软化点(SP)和TI含量来确定中间相转化程度.软化点约低于250℃、TI为75%左右时为初始中间相区域体形成阶段、半焦生成的前期.
关键词:
煤沥青
,
热转化反应
,
喹啉不溶物
,
中间相
刘勤
,
周善佑
材料研究学报
超塑性m-δ关系曲线可以分为m_L=m_(max)和m_L=m_(min)两大类型。均可由下面的C.L.(刘勤)m-σ方程表示:σ(%)=〔cε~(m-m_0)-1〕×100当σ=σ_0=0时,m=m_0≠0,C=C_0=κ_0/κ_0=1。当σ=σ_1(σ_(11),σ_(12),σ_(13),…,)时,m=m_1(m_(11),m_(12),m_(13),…),C=C_1(C_(11),C_(12),C_(13),…)=κ_1(κ_(11),κ_(12),κ_(13),…)/κ_0,当σ=σ_F时,m=m_F,C=C_F=κ_F/κ_0。对C 值进行“规划”,得到的C_1~(σ_O-σ_L)-(m_L=m_(max)),C_2~(σ_F-σ_L)-(m_L=m_(min)),C_3~(m_0-m_L)-(m_L=m_(max)和C_4~(m_F-m_L)-(m_L=m_(min))四种类型的“规划”方程分别对m_L=m_(max)和m_L=m_(min)型m-σ曲线适用。若m-σ曲线属简单的下降式,C 及其“规划”值均可近似地取1。否则,C-σ关系是应加以研究的问题。m 和k 值对σ值的效应可以分为动态(直接)和静态(间接)两种。最后的σ值是两种效应的综合结果。(注:m 和κ值见基本方程σ=κε~m)
关键词:
齐召庆
,
汪宏涛
,
薛明
功能材料
doi:10.3969/j.issn.1001-9731.2016.02.010
采用改进的非接触式混凝土收缩测定仪及标靶,研究了m(M)/m(P)比值(MgO与KH2PO4的质量比)对磷酸镁水泥石自收缩行为的影响,运用八通道微量量热仪、压汞仪、X射线衍射仪、扫描电子显微镜及能谱仪等分析手段,分析了m(M)/m(P)比值对磷酸镁水泥石自收缩的作用机理.结果表明,磷酸镁水泥石的自收缩呈现出3个阶段的特征,即早期的迅速收缩阶段、微膨胀阶段、收缩缓慢发展阶段.随着m(M)/m(P)比值的增大,由于磷酸镁水泥石的水化放热量降低,水泥石内部孔隙率增大,水化产物结晶度降低,水泥石结构疏松,所以,自收缩率减小.
关键词:
磷酸镁水泥
,
自收缩
,
m(M)/m(P)比值
Tesshu Miyahara
材料科学技术（英文）
Magnetic stripe is one of the major applications of magnetic materials. As a key component of the present card technologies magnetic stripes play reliable components for electronic data interchange in worldwide electronic payment systems such as financial cards, transit tickets and phone cards, etc. Magnetic stripes are available in various coercivity materials, widths, lengths, structures and colors with each types of transferable, lamination and pressure sensitive magnetic tapes of Deuton-M. Manufacturing process, structure and characteristics of Deuton-M magnetic tape and sheet are described.
关键词:
卞进田
,
孙晓泉
,
聂劲松
量子电子学报
doi:10.3969/j.issn.1007-5461.2008.02.019
为了得到2.7 μm波段可调谐激光辐射,设计了信号光单谐振荡KTP光参量振荡器(OPO),给出了KTP OPO II(B)类相位匹配方式下的角度调谐曲线、有效非线性系数.KTP晶体切割角为θ=62°,ψ=0°,有效非线性系数为-2.97 pm/V.利用该KTP OPO实现了2.6～2.8 μm波段范围可调谐激光输出,用脉宽为16 ns的基模高斯光束1.064 μm激光泵浦得到了最大能量578 μJ,能量转换效率达1.7%.
关键词:
非线性光学
,
可调谐红外激光
,
单谐振光参量振荡器
,
KTP
,
角度调谐
,
相位匹配
Journal of Physics-Condensed Matter
We investigated the stable (0001) surfaces of M(2)AlC (M = Ti, V and Cr) using the first-principles plane-wave pseudopotential total energy method. Four possible (0001) terminations were considered by breaking the M-Al and M-C bonds. The corresponding surface energies were calculated and compared. The Al-and M(C)-terminated (0001) surfaces demonstrated better stability than the C- and M(Al)-terminated surfaces by their much lower surface energies. In addition, the stability of surfaces was predicted under various chemical environments as a function of chemical potentials. We further investigated the character of surface relaxations. The electronic structures of the stable Al- and M(C)-terminated surfaces were analyzed.
关键词:
ab-initio calculations;ti3sic2 thin-films;electronic-structure;elastic stiffness;al;deposition;cr2alc;simulation;adhesion;solids
