Advanced Materials Research Vols. 194-196

Abstract: Based on the experiment, the author has made the finite element analysis of three steel-plate shear walls with concrete filled steel tube columns. The calculation results are very close to test results. It proof that the means of making models in this paper is reasonable and the results of the calculation are faithful. All of the study show that the materials used in the three walls have good seismic behavior.

Abstract: Underground subway RC structures suffered significant damage during many earthquakes, so it is important to study the seismic behavior on RC subway structure. The shaking table model test is made of the Beijing typical subway station structure. In this article, the test is introduced briefly; then, the acceleration history curves are analyzed. By the test, it is found that the interaction exits between structure and soil. Under the low intensity earthquake, the underground structure will exert a very small influence on soil and vibrates with soil; under the high intensity earthquake, the soil will exert a large thrust on the underground structure and the relative displacement exists between them. Moreover, At the bottom of the structure side wall, the peak acceleration is larger than it in soil around the place, and at the top and middle of the structure side wall, the peak accelerations are smaller than them in soil around the place; with the depth increase, decrease the peak value, the excellence frequency and its amplitude of the acceleration time history.

Abstract: Electrochemical impedance spectra (EIS) of two kinds of damage rate samples in natural seawater were measured and the relations between coating resistances and phase angles at high frequencies were analyzed. The results indicated that for the coating systems studied, the variation of phase angles at 14 kHz with immersion time was very close to the variation of coating resistance, hence may qualitatively reflect the coating with artificial defect degradation. This approach contains no error in calculation and the special phase angle parameters could be extracted easily from the EIS measured data. These phase angle parameters may be used as quick measurements to evaluate coating with artificial defect performance.

Abstract: Rock creep is a hot topic and key point in engineering geology. Based on renormalization group theory, the rock creep instability of micro-mechanism can be described as follow: with the expanding and interaction of micro-cracks and the main fault forms, which leads to failure. Comparing with the similarity of rock creep and rock compression process, and combining results of rock creep process, it is shown that there a distinct pertinence between different stages of rock creep. The relationship characteristics of different evolutionary stages can be used to provide scientific foundation for rock creep.

Abstract: During oil-drilling, the fractures of drill tool thread and piercement of drill pipe upset transition are very common in drill pipe failure as an object of petroleum and metallurgical researchers home and abroad. The classical fracture mechanics can only resolve the static fracture problem of oil country tubular goods (OCTG), but not resolve drill pipe failure under dynamic load. It is well known that the API 5D just prescribes strength criterion of drill pipe material but fracture toughness of drill pipe material. So, it is important to study dynamic fracture toughness of drill pipe material and present appropriate toughness criterion, which can not only optimize the drill string structural design, but also reduce fracture failure of drill string. On the basis of presenting main test means of dynamic fracture toughness and referring to the Charpy V test, the new impact experiment instrument is developed. Numerical and experimental comparisons show that the repeated dynamic fracture toughness tested by the impact experiment instrument is more accurate than one time impact, which can better show material characteristic and provide a reliable way to distinguish material characteristic, in the meantime, the correlations between dynamic fracture toughness of drill pipe material and failure of drill pipe is obtained.

Abstract: The swelling and water-retention capacity of bentonite in saline water are the important application properties of bentonite as the raw material of GCLs. In this paper, the swelling volumes and the filter loss of six kinds of Na-bentonite samples hydrated with different concentrations of NaCl, CaCl₂, and MgCl₂ solutions were investigated. In addition, the ion-exchange properties of raw materials, the morphology and structure analysis of the samples soaked in the salt solution were discussed. The results show that the water-retention capacity of bentonite decreases with the increase of salt concentration in aqueous solution; And at the same mass concentration, the water-retention capacity in MgCl₂ solution decreases most, followed by CaCl₂ and the least is NaCl. The water-retention capacity of bentonite in saline water is related with ENa⁺. The larger the ENa⁺ is, the better the chemical resistance of bentonite is.

Abstract: Perovskite relaxor ferroelectric PMN ceramics, Pb (Mg_1/3Nb_2/3O₃), have been fabricated using a two-stage process employing a corundum-type Mg₄Nb₂O₉ as a key precursor. The 100% perovskite PMN ceramics was revealed by X-ray diffraction analysis. The SEM image of the PMN ceramic shows irregular shape PMN grains on the porous surface. The surface chemical composition of the PMN ceramics could be characterized by X-ray photoelectron microscopy technique. The XPS results indicate most of the elements consist of more than one chemical species. The important of XPS studies here can reveal small amount of species which could not detected by XRD.

Abstract: An expeditious evaluation for photocatalyst is set up (or established) in this study. The optical transmittance of the methyl blue solution is measured, and a relationship between the transmittance of solution and its concentration is established. The performance of a photocatalyst can be evaluated via the distinct change of methyl blue solution. The TiO₂ films performed as a photocatalyst were prepared using sol-gel method and then annealed by rapid thermal annealing (RTA). The samples were illuminated with a high-pressure mercury lamp for exciting photocatalytic reaction. The result shows that TiO₂ photocatalyst degraded the methyl blue solution up to 97.8%.

Abstract: During materials manufacturing process will cause defects occasionally, if the defects located at near surface of material where the testing is not easy to implement. When the defects was stress by outside loading, it will grow up even become fracture, if the material apply ultrasonic testing then can increase material security to ensure structural safety. Practice material defect shape is variable and need complex product procedure. In this study, using wire cutting method to make practice defects specimen instead of the real flaws material, the specimen was made of medium carbon steel and aluminum alloy, defects away from the surface is 2-4 mm, defect shape including round shape hole and square shape hole, bore diameter was 1-3 mm. Using ultrasonic straight beam probe and delay line probe, straight beam probe have 5 MHz and 10 MHz frequency, and delay line probe have 5 MHz, 10 MHz frequency too, finally, compared the relationship between the accuracy and depth of flaws, pore size, flaw shape, material of specimen. Research results demonstrate that accuracy didn’t relate to the flaw shape, flaw size, depth of flaws and material of specimen. The accurately of 10 MHz delayed probe shown the depth of flaw smaller, the measurement than other probes.

Abstract: During the process of sewage treatment, some by-products are generated and among them, the sludge stands out, because of the largest volume and mass generated, and for containing heavy metals in its composition. Sludge is generally disposed of through land filling and spreading on reclaimed land. It has resulted in seriously contamination. It is necessary to improve the method of the disposal of sludge. Balanced with the environmental and economic benefit, the disposal of sludge, the economy and the environment can be optimized so as to realize the sludge stabilization, sludge reduction and sludge reutilization.