钛合金棒材成形过程的有限元分析与试验研究

采用 MSC.Marc 三维大变形热力耦合弹塑性有限元软件和接触分析技术,对Φ7.5 mm 的钛合金棒材四机架连轧过程进行了有限元仿真.对轧件的宽展、应力分布、轧制力、轧制力矩进行了分析,并在模拟的基础上进行了试验验证.试验表明:本次轧制钛合金棒材所制订的试验方案是合理的.模拟与试验相结合,为产品工艺设计提供了科学依据,以达到减少试验次数,降低试验成本的目的.     

煅烧制度对Li4Ti5O12材料结构与电化学性能的影响

研究高温固相合成Li4Ti5O12的煅烧制度,探讨Li2CO3与TiO2反应生成Li4Ti5O12的机理.分别采用一段煅烧(于800℃保温10 h)、两段煅烧(于800℃保温2 h,于650℃保温8 h)、低温预烧(于650℃保温8 h,于800℃分别保温2,4,6和8 h)3种高温固相煅烧制度合成Li4Ti5O12.研究结果表明:与一段煅烧和两段煅烧制度相比,在低温预烧制度下,随着高温阶段保温时间延长,合成产物中TiO2杂相含量逐渐减少直至消失;原料经650℃低温预烧8 h,再于800℃保温6 h条件下所得产物纯度达95%,仅含有少量富锂杂相Li2TiO3,材料首次放电比容量高达170.1 mA·h·g-1.     

Effect of trace Ce and B additions on the microstructure of Nb-3Si-22Ti alloys

The effects of trace Ce and B additions on the microstructure Nb-22Ti-3Si alloys were studied. The microstructure of the alloys was observed by scanning electron microscope (SEM), and their phase compositions were analyzed with X-ray diffraction (XRD) and Electro-Probe micro-analyzer (EPMA). The distributions of the elements were detected by Spectrum analyzer. The interface of the phases in the alloys was investigated by transmission electron microscopy (TEM). The results indicated that two phases of Nbss and Nb3Si presented in Nb-22Ti-3Si, Nb-22Ti-3Si-0.2Ce and Nb-22Ti-3Si-0.2B alloys. The segregation of Ti at the interface between Nbss and Nb3Si was promoted and the volume fraction of silicides in the alloy increased with the trace B and Ce addition to the Nb-22Ti-3Si alloy respectively. And there was no single and definite orientation relationship between Nb3Si and Nbss in Nb-22Ti-3Si, Nb-22Ti-3Si-0.2Ce and Nb-22Ti-3Si-0.2B alloys. Compared with the Nb-22Ti-3Si alloy, the Nbss superlattice structure was found in Nb-22Ti-3Si-0.2Ce and Nb-22Ti-3Si-0.2B alloys.     

显微组织对近α钛合金BT-20疲劳裂纹扩展的影响

通过显微镜及电子背散射衍射试验对近α钛合金BT-20的篮网、双态和魏氏组织微观结构及晶粒尺寸进行测定,并采用拉伸与疲劳裂纹扩展试验进行力学性能以及裂纹扩展研究,讨论微观组织对裂纹扩展速率、路径和断口形貌的影响.结果表明,双态组织的强度和延伸率最好,魏氏组织最差;双态组织的断口为解理断裂,裂纹碰到大尺寸初生α晶粒时发生穿晶失效,形态呈直线状,从而具有较高的扩展速率;篮网和魏氏组织的断口形式为沿相界断裂,裂纹扩展路径在通过α晶粒集束边界时改变方向,路径呈曲线状,扩展速率相对较低,从而具有较好的耐裂纹性能.     

Valence electron structure analysis of refining mechanism of Sc and Ti additions on aluminum

The mechanism of the difference of refining effect between Sc and Ti adding to aluminum can not be explained substantially with traditional theory. Valence electron structures of Al-Ti and Al-Sc alloys have been studied by using the empirical electron theory of solids and molecules (EET). The covalent bond electron numbers and interfacial electron density differences are calculated. The conclusion is that, in the two alloys, different covalent bond electron numbers of nucleation particles, and different electron densities on the interface between the second phase particles and the matrix, fundamentally lead to the difference of refining effect between Sc and Ti adding to aluminum. Supported by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050003042)     

H0.8Ni0.4Ti1.6O4/TiO2纳米复合材料的合成及光催化性质

用固相合成法制备出K0.8Ni0.4Ti1.6O4,并用离子交换法制备出H0.8Ni0.4Ti1.6O4;通过C6H13NH2层间膨胀,TiO2粒子的插入和紫外光分解等反应,合成出一种新的层状光催化纳米复合材料H0.8Ni0.4Ti1.6O4/TiO2.X射线衍射和漫反射等表征结果表明:该样品的层间高度为0.37 nm,禁带能隙为3.35 eV和2.58 eV.用可见光范围(大于400 nm)的光照射30 min,0.4 g样品可使甲基橙溶液(20 mg/L)的降解率达到21.9%,而同样条件下,标准TiO2(P-25)仅为6.2%,表明所研制的层状纳米复合材料具有较高的光催化活性.     

CaCu_3Ti_4O_(12)的驰豫特性

利用固态反应办法制备了CaCu3Ti4O12(CCTO)陶瓷样品;从德拜弛豫理论出发,通过介电温度谱得到弛豫时间温度谱,计算了样品的弛豫激活能H.结果表明激活能与频率无关,而弛豫时间因子τ0则与频率有关,显示出样品的弛豫特性并非来源于激活能H,而是来源于弛豫时间因子τ0的分布.     

Mg掺杂对锂离子电池材料Li4Ti5O12性能的影响

以固相反应法合成了尖晶石型Li4Ti5O12电极材料,通过掺杂Mg以提高其导电性及综合性能.XRD 表征了材料的结构特征,并通过激光粒度分析仪进行了粒度分析;用循环伏安、充放电曲线和循环次数考察了掺杂产物的电化学性能;在0.1C的放电倍率下放电,Li4Ti5O12的首次放电容量为158 mAh/g,结果表明掺杂了Mg的LiTiO产品的电化学性能和循环性能得到了很大改善.     

利用双波长光源测量透明膜的厚度

介绍了用双波长测量透明膜厚度的原理及方法,并人出了实验结果。     

二[(R-R'-环己烯基)-甲基取代茂]二氯钛和锆化合物的核磁共振和红外光谱研究

The NMR and FT\|IR Spectra of ten (ηC 6H\-9CRR′ Cp)\-2MCl\-2 (M=Ti,Zr) were measured.The constructions of the compounds were identified by 1H NMR and 13 C NMR spectra.All complexes are bonded by M\|Cp through center of Cp.The vibration modes were reasonably assigned,absorption of ν s M\|Cp (A\-1) (M=Ti and Zr) vibration all appear in 310?cm -1 or so,while ν as M\|Cp (B) appear around 410?cm -1 and 360?cm -1 for Ti and Zr respectively.The influence of the center metal atoms and the substituents upon the NMR and FT\|IR spectra were discussed.