Xiao Li Zhang

The Effects of Sintering Temperature on the Properties of Mg-Mn-Zn Ferrites

The present work shows the results of investigation on the effects of sintering temperatures of (Mg0.25Mn0.1Zn0.65)Fe2O4 ferrite on its sintered density, initial permeabilty, resistivity and microstructure. To achieve better sintered density and initial permeabilty, the sintering temperature should be ≥1200oC. However, the higher sintering temperature results in larger the grain size, which causes the reduction of the resistivities of Mg-Mn-Zn ferrites. Furthermore, the resistivities of samples are environmental temperature sensitive, and possibly possess the similar function of NTC thermistor over the testing range 25-225oC.

The Effects of SnO2 Doping on the Electrical Properties of ZnO Varistors

The SnO2 doping can increase the nonlinear coefficients of ZnO varistors, the highest α value is achieved at the 0.75 wt% doping level samples sintered at 1150oC. The improved I-V nonlinearity may be attributed to the donor behavior of Sn4+ ions. The SnO2 doping can enhance the ZnO grain growth that lower the breakdown field of doped samples.

The Electrical Properties and Impedance Analysis of ZnO Varistors Doped with Different Cu2O Contents

The Cu2O addition deteriorates the electrical properties of ZnO varistors, which is a good agreement with similar findings on Ag2O additions. The best fitted impedance analysis reveals that the Cu2O addition increases grain resistance and lowers the grain boundary resistance, results in low nonlinearity and higher leakage current of ZnO varistors.

The Thermally Stimulated Current (TSC) Technique on Evaluating Degradation of ZnO Varistors

Thermally stimulated current (TSC) is a simple and effective test technique to study the thermal activated charge, electron trap and activation energy of dielectric and semiconducting materials. It is well known that the addition of glass frits can improve the degradation property of ZnO varistors. An activation energy of 0.45 eV has been found on the ZnO varistors with/without glass frits after the DC degradation by using TSC method. The tested quantity of thermal activated charges, QTSC, may represent the numbers of migrated zinc interstitials. ZnO visitors doped with glass frits have less QTSC. Experiment indicates that TSC test is a convenient method to evaluate the degradation behavior of ZnO varistors.

Laser Processing Speed vs Morphology of Glazing Ceramics

Laser processing glazing ceramics is a new application of laser technique. This article presents the study of laser processing speed of glaze cladding. It found that the laser processing speed affected the morphology of glaze cladding significantly. Within the experimental conditions, rise of processing speed can decrease the depth of melted zone and the width of glaze cladding, vice versa.

The Effects of B2O3 Addition and Sintering Temperature on the Electrical Properties of SnO2 Based Varistors

SnO2 based varistor ceramics, as new type of varistor materials, have attracted increasing interest around the world. However, the effect of B2O3 addition on novel SnO2 based varistors is still unclear. In this paper the effects of B2O3 addition on the electrical properties and sintering temperature of the SnO2-Co2O3-Ta2O5 system were investigated. The experiments revealed that addition of trivalent boron can improve the densification of SnO2 based ceramics. The samples doped with 0.025mol% B2O3 had the highest sintering density. However between 0mol% to 0.1mol% B2O3 addition region there was little effect on non-linearity and breakdown field of SnO2-Co2O3-Ta2O5 system. Obviously, the sintering temperature had a predominant influence on the SnO2-Co2O3-Ta2O5 system; the samples sintered at 1400°C were superior to those sintered at 1350°C.

The Effect of Parameters of Laser Processing on the Morphology of Glaze Cladding

Laser processing ceramic materials is a new application of laser technique. This paper presents the study of laser processing parameters of glaze cladding. It found out that the parameters of laser processing affected the morphology of glaze cladding significantly. Within the experimental conditions, rise of output power or drop of processing speed can increase the depth of melted zone and the width of glaze cladding, vice versa.

The Optimum Microstructure of Reheated X80 Bend Pipes

Bend pipes are key points in construction of pipeline. The world well known second west east pipeline project will use X80 pipeline steel in whole line. So the study on X80 grade bend pipe is very important and timely. Here , a series of experiment were done to optimize the microstructure of X80 bend pipes, and corresponding reheating technics were studied. By compare with current standard used in china, the CVN toughness and shearing area and strength were discussed. By this research, the optimum reheating program for X80 grade bend pipes were gained.

Shrinkage Properties of Wool Treated with Ionic Liquid and Chitosan Biopolymer

In order to improve the shrinkage resistance of wool fabrics, a new method that combine ionic liquid and chitosan was researched in this paper. Wool fabric was first pretreated with 1 - butyl - 3 - methyl bromination imidazole([Bmim]Br）, and subsequently was treated with chitosan. Pretreatment temperature and time, and chitosan concentration of post-treatment were studied in this paper. Results showed that wool fabrics treated with [Bmim]Br at 80°C for 2 hours and post-treated in 1.0% chitosan acetic acid solution exhibit good shrinkage resistance. In addition, SEM images of ionic liquid treated wool fiber indicates that the scales have been destroyed, and the surface is covered with a layer of film after post-treated with chitosan.