Advanced Materials Research Vol. 815

Abstract: The corrosion behavior of commonly-used steels in the oil-containing and alcoholic sewage from gas field was studied combined with polarization curves, electric impedance spectrum (EIS), dynamic corrosion weight loss test, scanning electron microscope (SEM) and energy spectrum (ES) of corrosion products. It was shown that corrosion rate increased with the sequence of 316L, 16Mn, 20#, L360 and 20R steels, and 316L steel was corroded more slightly than 16Mn, 20#, L360 and 20R steels. There were some spot corrosion pits on the surface of L360 and 20R steels. A higher Chromium content of 316L steel led to a stronger corrosion resistance. Ferrous carbonate was the mainly corrosion product on the surface of the four steels. While the corrosion product on the surface of L360 and 20R steels was poor adhered and easy to fall off, and formed some corrosion pits on the steels surface.

Abstract: Prepare Ni60A on the H13 steel matrix in thermal spraying. Then, the alloy layer is treated with electron beam in multichannel lapping. Microstructure, the direction of grain growth, the situation of crack initiation on surface modification are analyzed and researched by optical microscope,electron scanning microscope,energy disperse spectroscopy. Experimental results show that the alloy layer which is scan with an electron beam is fuse together with the steel matrix. The organizations of the strengthened layer are dendritic crystal and columnar crystal. Moreover, the grain refinement is well done. Some microcosmic or macroscopic crack appear in the scan regions.

Abstract: So as to decrease the cost and time of the development, it is significance to solve the section instability problem of diameter-expanded conductor during the design stage. The solution is developing a finite-element simulation program for the study of section stability; however, a proper modeling method is not necessary. In this paper, the parametric study on simulation modeling of diameter-expanded conductor is carried out and through the investigation, analysis and verification; a kind of test method has been designed for the study. After a series of test under different tensions, the numbers of sheave, the position of strand jumping, the section states and the indentation states have been gotten. At last, a parametric finite-element program for strand jumping prediction has been simulated and the result shows that the code developed is reliable based on the comparison of the calculated results and the measured ones.

Abstract: Our team proposes the design concept of layered composite electrode materials. Change the single substrate of traditional electrode material by using thermal pressing diffusion welding to synthesize sandwich structure electrode substrate of titanium cladding aluminum. Only Al₃Ti phase is obtained in the composite interface. First-principles calculations have been used to calculate the formation enthalpy and binding energies, and the respective order of their value are as follows: AlTi₃2Ti3Ti,AlTi₃2Ti3Ti. AlTi₃ near Fermi surface is zero and it has good conductivity. It has the strongest bonding capability and stability. Practical application of this new anode in the field of hydrometallurgy has good conductivity, strong adaptability.

Abstract: To diagnose the arc erosion type and improve arc erosion resistance of Ag/LSCO (Ag/La_0.5Sr_0.5CoO_3-δ) contacts, making and breaking experiments were carried on Ag/LSCO(12) contacts prepared by both traditional powder metallurgy method and a modified one in this work. Arc erosion and morphological characters of this two kinds of Ag/LSCO(12) samples were investigated and the erosion mechanisms were also discussed. The results are that seven types of arc erosion morphologies of Ag/LSCO(12) contacts were classified as the lump region, the cauliflower region, the framework structure, holes and cavities, cracks, spongy region and the vestiges of fusant spreading. There are intrinsic links between these morphological characters. The spongy regions and vestiges of fusant spreading on the contact surface of Ag/LSCO(12) prepared by the new method indicates that its resistance to arc erosion is superior to the contacts prepared by traditional method.

Abstract: The oxide layer formed and removed on the surface of the grinding wheel has a significant influence on the grinding quality of ultrasonic-ELID multiplicate grinding. In this paper on the basis of the principles of electrochemical and ultrasonic vibration, the mechanisms of oxide layer formation and remotion were analyzed. Then, the predictive modeling of oxide layer thickness was proposed. The effects of main factors on the oxide film thickness were simulated and analyzed theoretically. The simulation results show that the layer thickness decreases with the decrease of the duty ratio or the grain volume ratio or the ultrasonic frequency ,and the increase of the electrode gap during the composite grinding process.

Abstract: Polyimide (PI) was chosen as the matrix of the composites, barium titanate/polyimide (BT/PI) nanocomposite films were prepared with in-situ polymerization. The morphology of the samples was obtained by SEM. The factors affecting the dielectric properties are discussed. When the mass fraction of BT is 70%, the dielectric constant will be 19.32, and loss 0.00254 (at 10³ Hz). The optimal solvent content and ultrasonic time were 9.2 ml and 30 min respectively. TG analysis shows that the film is stable below 500°C. The AC breakdown strength were 42 MV·m^-1 and 64 MV·m^-1 for 70% BT/PI and 60% BT/PI respectively, and corresponding energy storage density were 0.17 J·cm^-3 and 0.30 J·cm^-3 respectively.

Abstract: In the field of communication direction finding by using antenna array, multi path effect arouses great attention. It not only increases the number of arriving waves, but the multi arriving signals are coherent. In order to solve the problem brought by multi path effect, much more elements are needed for multi arrival direction estimation after cancelling coherence processing which also requires more elements by spatial smoothing method. The method of frequency domain process is used in this paper to reduce the coherence between signals. The principal reason is that there is various wave distance difference between the multi arriving waves. The phase lag is not the same for different arriving path. Therefore we can adopt wide band receive process. The spatial vectors for different frequency component are not coherent, so it needs less elements for the array in the same case. The simulation results prove it is practical.

Abstract: The study is based on wind power tower drum with Q345E low alloy steel weld detection of magnetic memory method, combining with the characteristic of X-ray photos of magnetic memory formation mechanism and made a detailed analysis. By doing this, it aims to show that increasing scan device on the number of channels, can to a certain extent, improve the accuracy of detection. Magnetic memory method is proved to be able to predict the nondestructive testing artifacts of the early damage and the possibility of micro crack germination to some extent. It shows that the weld seam can be quickly found dangerous parts by using the magnetic memory test full scan, coupled with the X-ray testing technology for defects, and it also can be further qualitative and quantitative and significantly improve the detection efficiency.

Abstract: A new method for synthesizing magnetically responsive Fe₃O₄@UA@AA nanoparticles have been reported in this paper. The superparamagnetic Fe₃O₄@UA nanoparticles were prepared via carboxyl-functionalization of 10-undecenoic acid and Fe₃O₄@UA@AA made by a polymerization of 10-undecenoic acid on the surface of nanoparticles with acrylic acid. Thus the magnetic nanoparticles were functionalized with carboxylic groups. The compositions of as-prepared nanoparticles were characterized by FTIR, TGA, TEM, VSM and conductivity titration. Under optimized experimental conditions, Fe₃O₄@UA@AA nanoparticles with diameter of about 20 nm and 0.437mmol/g of carboxyl groups and 65 emu/g of saturation magnetization were prepared successfully.