Advanced Materials Research Vols. 415-417

Abstract: With the development of high-rise buildings, the requirement to the performance of steels for high-rise buildings keeps on increasing. Besides high strength and high toughness possessed by general structural steels, the steels for high-rise buildings should possess low yield ratio, excellent welding performance, fire-resistant performance and Z-direction performance. These performance characteristics of the steels for high-rise building were introduced and its development trend was pointed out.

Abstract: Hot compression test of coiled tubing steel is performed on Gleeble3500 at 1123K—1373K and strain rate from 0.001 to 5s-1. The hot deformation behavior of coiled tubing steel was characterized using processing map developed on the basis of the dynamic materials model. The processing map gives the flow instable region and the flow stable region in which the process of dynamic recovery (DRV) and the dynamic recrystallization (DRX) occur. In the processing map, the variation of the efficiency of the power dissipation is plotted as a function of temperature and the strain rate. According to the processing map, the coiled tubing steel is rolled by The Thermo-Mechanical-Control-Process (TMCP), and finally it is obtained that the yield strength and tensile strength of coiled tubing steel are 565MPa and 685MPa respectively, and the elongation percentage is 32.1%.

Abstract: Against data dispersion processing of electronic component life, this paper introduced the unascertained theory to eliminate variable data, which avoid the missing and distortion of information, and we can get more accurately data through small sample. By choosing different neighborhood radius to control the final results this method improved the anti-interference ability of the data variation, and optimized the stability of the data.

Abstract: The Self-Assembled (SA) films of glutamic acid derivatives were prepared on the iron surface. Electrochemical impedance spectroscopy (EIS) and polarization techniques were used to investigate the protection abilities of these films against iron corrosion in 0.1 M H2SO4 solution. The results of EIS and polarization curves indicated that films of the glutamic acid derivatives were able to protect iron from corrosion effectively.

Abstract: Research is tested by the ways of microwave reduction-weak magnetic separation for recycling niobium and iron based on the preparation concentrate of rough niobium. Reduction is performed in 4 temperatures which are 700°C、750°C、800°C and 850°C for the ore, then weak magnetic separation test is taken in 4 current which are 0.6A、0.8A、1.0A and 1.2A, for the purpose of analyzing effect of magnetic current on the dressing index. The results show that, in these 4 types of temperature, hematite in the ore is well reduced to magnetite. At the temperature of 850°C, part of magnetite will be further reduced to FeO. The more the magnetic current is, the higher preparation concentrate producing rate and the iron yield are, but the purity may be a little going down. The higher the reducing temperature is, the more obvious the purity will be; the yield of Nb₂O₅ in tailing ore falls down with the rising up of the magnetic current, and the purity is a little bit going up. The higher the temperature of reduction is, the more obvious the yield falls. Considering the dressing index of both preparation concentrate and tailing ore, the best dressing index should be proceeding in the current of 1.2A, at the temperature of 750°C, yield and grade of the preparation concentration iron are 91.34% and 54.66% respectively, and yield and grade for Nb₂O₅ in tailing ore are 70.63% and 7.12% respectively.

Abstract: The martensite start temperature (Ms) of a Fe-0.40%C-1.87%Mn-1.65%Si alloy with bainite and martensite dual phases was studied. The phase transformation dilation curves were measured and Ms temperatures of deformed and non-deformed specimens were obtained. Finally the effect of bainitic transformation upon Ms was investigated. The results show that bainitic phase transition affects the Ms and the increase of transformation results in the decrease of Ms. The mechanical stabilization of austenite due to ausforming is partially eliminated by bainitic transformation, which weakens the effect of ausforming on Ms.

Abstract: 0.95 (Na_0.5Bi_0.5)TiO₃-0.05 BaTiO₃ (NBT-BT3) compositions with excess x wt% Bi₂O₃ (NBT-BT3-x, with x=0, 1, 2, and 3) are sintered at 1200°C. When excess Bi₂O₃ is added, the NBT-BT3-1 ceramic displays the largest grain sizes, after which the grain sizes apparently decrease as more excess Bi₂O₃ is added. The lattice constants of calcined NBT-BT3 powder and NBT-BT3-x ceramics are calculated by the Rietveld full-pattern refinement method using the XRD standard pattern of ICSD-154041 and the measured XRD patterns of NBT-BT3-x ceramics. The refined values are compared with the measured XRD patterns to determine the cause of the distortion in the NBT-BT3-x ceramics. We show that NBT-BT3-1 ceramic has the minimum lattice constant a and maximum lattice constant c. The effects of excess Bi₂O₃ content on the dielectric properties of NBT-BT3-x ceramics are also discussed.

Abstract: Description of crack initiation behavior under thermo-mechanical fatigue (TMF) of modern high chromium steel is prerequisite for design optimization of steam turbine components. In this paper a phenomenological method which envelopes the synthesis of stress-strain hysteresis loops according to cycle counting methods and the individual assessment of creep fatigue damage is extended to TMF with superimposed creep. Recalculation of such service-type experiments on specimen of rotor steel 10CrMoWVNbN shows acceptable results for deformation description and lifetime estimation.

Abstract: Three-dimensional reticulated structure silicon carbide ceramics foam is used as filter element materials of diesel exhaust particulates filter. According to the flow state of diesel exhaust, adopting Navier-Stokes equation calculating analysis and combining with experimental results, the backpressure formula of diesel exhaust filter whose element is silicon carbide ceramics foam is determined. The calculation data agree with the experimental results very well.

Abstract: The barium-excessive BaTiO₃ ceramics with BN addition for laminated positive temperature coefficient (PTC)thermistors are fabricated. The tape casting technique and reduction/reoxidation process are employed into the fabricating procedure. The influences of BN additive on ceramic characteristics are discussed. The addition over 5% leads to rectangular and abnormal large grains. The 5% BN-doped ceramics shows a resistivity of 233 Ω•cm and PTC jump of 3.4 orders of magnitude. The charge carrier density in grain bulk and acceptor state density at grain boundaries are evaluated. The correlation of BN doping amount with room temperature resistivity, PTC jump, reoxidation effect as well as charge carrier and acceptor state density are investigated.