Advanced Materials Research Vols. 1061-1062

Abstract: The impact of CO₂ partial pressure ,fluid producing rate and corrosive medium on the CO₂ corrosion regularity of N80 steel and the inhibition efficiency of imidazoline inhibitor are investigated respectively through simulation of the actual working environment in the mined-out space of mechanical oil production wells by using high temperature and pressure reactor. According to the results, the corrosion rate of metals increases with CO₂ partial pressure but the inhibition efficiency of the inhibitor is hardly affected when CO₂ partial pressure in the scope of 1~3MPa. The increase of the fluid producing rate will accelerate the corrosion of metals and the inhibition efficiency will decline. With corrosion inhibitor applied, metals corrode slower in the liquid phase than in the gas in the initial stage, but latterly the corrosion rate is gradually higher than that in the gas phase.

Abstract: Alternating traveling magnetic field (TMF) was introduced to agglomerate the inclusions with a density smaller than surrounding melt. Primary silicon particles precipitating from the solidification process of hypereutectic Al-Si alloy was regarded as inclusions need removing. Results indicated that alternating TMF was more effective to promote the inclusions to agglomerate into clusters than downward TMF. The effect of alternating TMF to agglomerate the inclusions increases with the increase of current and frequency. There exists the best alternating time to get the best agglomeration effect. In this study, 10s is the best alternating time.

Abstract: Samples of duplex stainless steel were plasma nitrided at different atmosphere proportion and nitriding time. The hardness and the corrosion resistance of the untreated and various plasma treated samples were characterised by a variety of analytical techniques. The results show that plasma nutriding at low temperature can improve hardness of duplex stainless steel and its corrosion properties at the same time. Declining the atmosphere proportion of ammonia and argon can effectively prevent the nonuniformity of hardness of nitriding layers and extension of nitriding time is conducive to enhance the hardness and thickness of nitriding layer. In addition, the corrosion peoporties of duplex stainless steel nitrided increase when the nitriding time improves, but its corrosion resistance rises slowly after nitriding for 9h.

Abstract: The electrochemical behavior of Fe-Cr-Mo codeposition was investigated by using linear scanning. The deposition potential of Fe2+ shifted negatively after adding glycine and additive W, while the deposition potential of Cr3+ had no obvious change, then the purpose of codeposition was achieved. Induced codeposition occurred after adding molybdate into the solution, at last alloy coating of good appearance was obtained.

Abstract: Because of high purity aluminum’s excellent performance in the electronics industry, it has become more and more popular. Aluminum purification technology is the key to the development of high-purity aluminum, in this paper, through self-purification equipment and directional solidification method to explore the effect of k₀ to the element purification rate during the produce of high-purity aluminum. Found that when k₀ is less than 1, the smaller the value is, the better the purification is.

Abstract: The Mg-doped (Ba_0.97Ca_0.03)(Ti_0.96-xZr_0.04Mg_x)O₃ piezoelectric ceramics were prepared by conventional sintering technique. Influences of MgO doping content on the phase structure and dielectric, piezoelectric, and ferroelectric properties were investigated. The XRD patterns suggested that a morphotropic phase boundary (MPB) crossing pseudocubic and tetragonal symmetries occurs at the compositions containing 0.5~0.7 at.% Mg. Because of such transitional behavior, the piezoelectric coefficient (d₃₃), electromechanical coupling coefficient (k_p), and remanent polarization (P_r) were enhanced to peak values, 327 pC/N, 37.2%, and 15.79 μC/cm², respectively. However, the dielectric constant (ε_r) showed a decreasing tendency with raising Mg content.

Abstract: In this paper, the effects of different sintering temperature on the microstructure and piezoelectric properties of Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3(PNZZT) ceramic samples were investigated. The Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3 ceramics materials was prepared by a conventional mixed oxide method. In the period of the experiment, the relationship between crystallographic phase and microstructure were analyzed by X-ray diffraction(XRD) and scanning electron microscopy(SEM) respectively. The XRD patterns shows that all of the ceramic samples are with a tetragonal perovskite structure. Along with sintering temperature increased and the x is 0.03, the grain size gradually become big. Through this experiment, it has been found that when the x is 0.03 and sintered at 1130°C for 2 h, the grains grow well, the grain-boundary intersection of the sample combined well and the porosity of the ceramics decreased, an excellent comprehensive electrical properties of the Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3 samples can be obtained. Its best electrical properties are as follows: dielectric constant (ε) is 1105, dielectric loss(tg) is 0.017, electromechanical coupling coefficient (Kp) is 0.287, piezoelectric constant(d33) is 150PC/N

Abstract: In order to investigate the fabrication of pyrochlore Gd₂Zr₂O₇, Gd₂O₃ and ZrO₂ were used as raw materials in the process. Pyrochlore Gd₂Zr₂O₇ were fabricated by high temperature solid state reaction at 1100 – 1600 °C under atmospheric pressure for 72 h. XRD and SEM studies were exploited to characterize the crystal structure and microstructure of the synthetic samples. The results revealed that Gd₂Zr₂O₇ with a single pyrochlore structure was fabricated successfully at 1500 °C. The microstructure of the sample was uniform and dense, and the grain size was in the range of 1 - 3 μm.

Abstract: (K,Na)NbO₃(KNN)-based lead-free piezoelectric ceramic could be fabricated by ordinary solid sintering method.This paper reported preferable properties of solid solutions (1-x)(Na_0.535K_0.480)NbO₃-xLiNbO₃ (x=0.050,0.055,0.060,0.065 and 0.070 successively) all sintered at 1060°C.The nonconservation of charge suppressed negative effects caused by evaporations of K&Na and doped Li occupied A sites in ABO₃ perovskite structure lattices led to the intensification of lattice distortion.XRD result showd phase transition from coexistence of orthorhombic and tetragonal symmetry to tetragonal.Polymorphic phase boundary could be observed when 0.050≤ x≤ 0.060.Coexistence of orthorhombic and tetragonal phases brought improvements of piezoelectric coefficient d₃₃ and electromechanical coupling factor kp,whose top values were 162 pC/N and 28.1% in this paper. Positive correlation between the Curie temperature and Li content proved that a distorted crystal lattice needed more energy to accomplish its phase transition from tetragonal to cubic than a normal one.

Abstract: In order to improve the thermal conductivity of silicone, we prepared silicone/carbon nanotube array (CNTA) composite by immersing the CNTA into silicone solution and cured at 110 °C. The thermal conductivity of silicone and silicone/CNTA composite was measured by laser flash method at 30 °C, 60 °C, 90 °C, 120 °C, which are usually the operating temperatures. It was found that the thermal conductivity of silicone/CNTA composite increased with the temperature until achieved the plateau near 90 °C. The maximum thermal conductivity of silicone/CNTA composite is 0.674 W/mK, which is 220% higher than that of neat silicone. The excellent thermal conductivity makes the composite a promising thermal interface material.