Microstructure of Nanostructured WC-Co Coating Prepared by Thermal Spraying

Nanostructured WC-Co coatings were produced with Atmospheric Plasma Spraying (APS) and Low Pressure Plasma Spraying (LPPS). Microstructure characteristics and phase compositions of the coatings were studied by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The microstructure compositions were analyzed with EDS. During APS deposition the existence of oxygen causes the decarburization of the coating, and the coating was composed of melted area and the WC/12Co powder. Besides WC phase, there was W2C phase. However in the coating deposited by LPPS the content of oxygen was so low that there were a limit degradation of the WC/12Co powder. The coatings were made up of compact block and loosen porosity area. There were large quantities of nanostructure WC grains and a small quantity of microstructure WC grains presented in the coating. Besides WC phase, a little W2C and WC1-x or Co6W6C phases occured. Consideration of the characteristics of the highly porous, spherical-shell morphology of nano-WC/12Co power, heterogeneous melting and localized superheating of the power were two main factors which caused the microstructure and phase composition of nano-WC-Co coatings.     

Static Stiffness Analysis of a New Type 6-DOF Micro-manipulation Robot

A 6-DOF micro-manipulation robot based on a 3-PPTTRS mechanism is proposed in this paper. Its static stiffness is an important index to evaluate load capacity and positioning accuracy. However, it is insufficient to consider the static stiffness only when the robot is in its initial pose. The stiffness in different positions and poses in its work space must be analyzed also. Thus a method to analyze the relationship between static stiffness and poses in the whole work space is presented. A static stiffness model is proposed first, and the relationship between structural parameters and static stiffness in different poses is discussed. The static stiffness analysis provides foundation for structural parameter design.     

Quantum theory analysis of the action micromechanism exerted on bioparticles from laser microbeams

The effect of laser microbeam trapping the bioparticles has been appfied widely in the biology .However the micromechanism of the acting that realizes the laser-microbeam trapping bioparticles is still lacking. In this paper ,the act microchenism of the gradiant force of laser microbeam for the bioparticles is analysed by means of quantum theory ,The result accords with our experiment.     

The effects of PMD and PDL on the performance of OOK and DPSK systems

Using multiple importance sampling （MIS） technique, the optical communication system performance affected by polarization-mode dispersion （PMD） and polarization-dependent loss （PDL） is simulated numerically. The power penalties and system outage probabilities are obtained for optical communication systems with on-off keying （OOK） or differential phase shift keying （DPSK） modulation. The simulation results show that DPSK always performs better than OOK. When the system has moderate PDL （about 1.5 dB）, it is necessary to compensate effectively the fiber PMD in order to enhance the system tolerance to the PMD and PDL. However, the efficiency of PMD compensation will degrade rapidly when the PMD of the whole optical link drops into the low value.     

Regulations and Practice on Flue Gas Denitrification for Coal-Fired Power Plants in China

In China, according to the relative up-to-date regulations and standards, the maincontrol measure for NOX emission of coal-fired power plants is, in principle, low NOXcombustion. However, in recent years, more and more newlyapproved coal-fired plantswere required to install flue gas denitrification equipment. This article expounds if fluegas denitrification is necessary from several aspects, including constitution of NOX, itsimpact to environment, operation ofdeNOXequipment in USA, as wellas the differencei...     

7—氨基头孢烷酸中残留N，N—二甲基苯胺的HPLC分析

采用反相高效液相色谱的外标法 ,分离测定 7-氨基头孢烷酸中残余溶媒N ,N -二甲基苯胺的含量 ,用C1 8色谱柱( 2 0 0mm× 4.6mm ,5 μm ) ,以甲醇 :水 ( 70 :30 )为流动相 ,检测波长 2 5 4nm。方法的线性相关系数为 0 .9990 ,回收率平均值 97.8% ,标准偏差 1.2 %。本方法可准确用于 7-ACA残媒的分析测定。     

PRECIPITATION SELECTIVITY AND GROWTH OF PEROVSKITE PHASE FROM TITANIUM BEARING BLAST FURNACE SLAG

The effects of transformation of slag composition and additive agents on the morphology, the precipitation behavior, the crystal growth, and the volume fraction (VF) of perovskite (CaO·¤TiO_2) crystal in the Ti-bearing blast furnace slags were investigated. As the morphology of perovskite is dispersed in molten slags, the crystal growth mechanism of the melting of fine dendrites and the coarsening of large grains exist throughout the solidification of molten slags. With the increase of CaO and Fe_2O_3 content, VF of perovskite obviously increases. However, high basicity leads to the viscosity of slag, which results in the reduction of the average equivalent diameter (AED). The experimental results showed that the presence of the additives CaF_2 and MnO efficiently decreased the viscosity of the slags, and obviously improved the morphology of perovskite and promoted its growth.     

Mechanical Properties on Ni3 Al Intermetallic Compound-SiC Composite Material Generated by SHS Method

0 Introduction The Ni3 Al intermetallic compound is of great interest because of its corrosion-resistance, and high melting point. However, it is difficult to make the intermetallic compound using the ordinary method.     

谷氨酸发酵过程中发酵液发红原因的研究

<正> 前言 目前国内使用的谷氨酸生产菌种,在正常的发酵条件下,谷氨酸发酵液的颜色是土黄色、或浅黄色;但当发酵异常时,往往会出现发酵液发红的现象,给提取带来一定的困难影响提取收得率和降低谷氨酸质量。关于谷氨酸发酵过程中为什么会产生发酵液颜色发红的现     

Petroleum Discoveries and Exploration Prospect in China＇s Major Petroliferous Basins

Up to now, there are 29 oil- and gas-bearing basins with recoverable oil and gas reserves in China. However, most of the reserves were mainly discovered in parts of the 29 basins, which played an important role in China＇s petroleum exploration and development. Based on the data statistics and analyses of reserves and resources, the current situation of oil and gas discoveries and the resources potential in these major basins are discussed in the paper. The so-called major oil- and gas-bearing basins here are the basins with cumulative recoverable oil （excluding condensate oil） reserves of more than 50 million tons or cumulative recoverable gas （excluding dissolved gas） reserves of more than 50 billion cubic meters.