Investigation on gradient material fabrication with electron beam melting based on scanning track control

A new electron beam control system was developed in a general vacuum electron beam machine by assembling with industrial control computer, programmable logic control （PLC）, deflection coil, data acquisition card, power amplifier, etc. In this control system, scanning track and energy distribution of electron beam could be edited off-line, real-time adjusted and controlled on-line. Ti-Mo gradient material （GM） with high temperature resistant was fabricated using the technology of electron beam melting. The melting processes include three steps, such as preheating, melting, and homogenizing. The results show that the GM prepared by melting technology has fine appearance, and it has good integrated interface with the Ti alloy. Mo and Ti elements are gradually distributed in the inter.face of the gradient material. The microstructure close to the Ti alloy base metal is α ＋ β basket-waver grain, and the microstructure close to the GM is a single phase of β solid solution.     

TPR处理剂的研究

利用活性单体苯乙烯与氯丁橡胶、高苯乙烯热塑弹性体接枝聚合，所得产物稀释后用于ＴＰＲ（ＴｈｅｒｍａｌＰｌａｓｔｉｃＲｕｂｂｅｒ）粘接前的预处理，可明显提高剥离强度。     

The deposition of coke from methane on a Ni/MgAl2O4 catalyst

Temperature-programmed reaction techniques and Raman spectroscopy were used to characterize coke species deposited on a 5% Ni/MgAl₂O₄ catalyst for dry reforming of methane. The CH₄ temperature-programmed decomposition profiles showed that the ignited decomposition temperatures of CH₄ increased from 273 to 378 °C when MgAl₂O₄ replaced the catalyst support γ-Al₂O₃. The temperature-programmed oxidation, temperature-programmed hydrogenation and temperature-programmed CO₂ reaction profiles showed that there were three carbon species (i.e. C_α, C_β and C_γ) on the catalyst surface. Raman spectroscopy showed that C_γ was graphite-like carbon species, which was responsible for catalyst deactivation. The C_γ species was the most inactive species toward H₂ and O₂, while it was unexpectedly more active toward CO₂. The unique reactivity of CO₂ with different coke specie could be ascribed to the carbonate, bidentate and formate species formation on MgAl₂O₄ surface. These surface species enhanced the oxidation of C_γ species and thus contributed to the high stability of Ni/MgAl₂O₄ catalyst.     

3-氨基-4-氯苯甲酸十六酯的合成

以3-氨基-4-氯苯甲酸和正十六醇为原料，二甲苯为溶剂，对甲苯磺酸为催化剂酯化合成3-氨基-4-氯苯甲酸十六酯。采用傅里叶红外光谱（FTIR）、核磁共振光谱（NMR）的方法对产品的结构进行表征。考察了醇酸摩尔比、催化剂加量、反应物浓度对酯化率的影响。结果表明：醇酸摩尔比1.2:1，催化剂用量为总质量5%，反应物浓度65%，反应时间7 h，酯化率达96.20%，单程收率为73.91%。研究确立了产物提纯、提高单程收率和滤液去除催化剂后回收、重复使用的最佳系统工艺路线，单程收率提至78.90%，总收率为82.62%，产品的纯度高于使用标准。     

Crystal Chemistry and Phase Transitions in Substituted Pollucites along the CsAlSi2O6-CsTiSi2O6.5 Join: A Powder Synchrotron X-ray Diffractometry Study

The crystal structures for a suite of substituted pollucites with the compositions CsTi _x Al_{1– x} Si₂O_{6+0.5 x} , 0 ≤ x ≤ 1, have been determined from Rietveld analysis of powder synchrotron XRD data. Our results indicate that the pollucite end member (CsAlSi₂O₆) has a tetragonal structure (space group I 4₁/ a ), whereas all other compositions are cubic (space group Ia 3 d ). The increased symmetry for the titanium-substituted structures is presumably due to the incorporation of additional O²⁻ anions (needed for compensating the charge imbalance between Ti⁴⁺ and Al³⁺), which effectively holds open the expanded cubic framework. In situ cooling experiments of the substituted phase CsTi_0.1Al_0.9Si₂O_6.05 reveal a displacive transformation to the tetragonal structure at ∼230 K. This transformation is tricritical in nature and is analogous to the tetragonal-to-cubic transition in pollucite on heating.     

常温清洁铁系磷化液研究

为使磷化实现一级清洁生产,开发了一种用于钢铁表面涂装前处理的常温清洁铁系磷化液。该磷化液组分所有的成分均参加成膜反应生成磷化膜、水、沉渣或在磷化膜干燥过程中挥发。此磷化液不含亚硝酸盐和重金属,在5~40℃下浸渍磷化5~10 m in,在每平方米即可生成质量约为0.7 g的膜和耐CuSO4溶液点滴时间达90~140 s的彩色磷化膜。且磷化后可免水洗。     

Braking Behavior of C/SiC Composites Prepared by Chemical Vapor Infiltration

Carbon fiber-reinforced silicon carbide matrix composites have the potential to overcome the shortcoming of the currently used carbon/carbon friction materials in aircraft brakes. In this article, the carbon/silicon carbide (C/SiC) composites were prepared by chemical vapor infiltration method, and the brake disks with different densities and component content were finally obtained. The friction coefficient and friction stability can be significantly improved by increasing both material density and carbon content. When the density of C/SiC composite is 2.3 g/cm³, the coefficient of friction measured is 0.23, the coefficient of friction stability remains about 0.43, the liner wear rate is less than 9.3 μm/cycle, and the weight wear rate is less than 9.1 μm/cycle. The rapid increase of friction coefficient approaching the end of braking is mainly related to the increasing of surface temperature in a short time and the enhanced adhesion and abrasion of contact conjunctions and asperities. The C/SiC composites exhibited a good stability of braking against fading versus the braking number and surface temperature. The surfaces of C/SiC brake disks were covered with wear debris including the fragment of carbon fibers after the braking tests. The wear on the surfaces is significantly determined by cyclic mechanical and thermal stresses, which result in the micro-cracks in the SiC matrix, the thin flakes of the surface materials as well as the grooves.     

突发GMSK混和信号混合位置估计迭代算法

针对GMSK混合信号的混合位置估计问题,提出了一种基于参数估计与混合位置估计的迭代算法。混合信号混合部位和未混合部位在幅度和频率上存在明显差异,通过混合部位信号过零点和极值点得到混合的信号和幅度估计后,可以对采样点是否混合进行判断,同时混合起点对应着相对时延,当混合信号的相对时延较大时,利用未混合部位信号来进行迭代时,其估计精度更高。对混合起点估计的克拉美罗界进行了推导,仿真表明,本文算法估计精度高,所需的数据量小,适用于突发通信,且对参数变化不敏感,具有较强的鲁棒性,在高信噪比下混合位置估计精度接近克拉美罗界。     

神经网络在聚合过程中的应用

介绍了神经网络在聚合反应过程中的建模，预测、优化，控制和故障诊断及模式识别方面的应用，讨论了其优点和局限性，并分析今后神经网络的发展趋势。     

HDPE／MPA层状容器加工及其阻透性能的研究

本文讨论了HDPE/MPA层状容器的加工以及MPA用量和贮存时间对阻透性的影响,分析了透过滞后、气相和液相透过现象。