Advanced Materials Research Vols. 146-147

Abstract: Marshall test design methods are used to design TLA modified asphalt mixture and base asphalt mixture respectively, and their pavement performance is tested. The results showed that there is a transforming coefficient of 1.15 between OAC of TLA modified asphalt mixture and that of base asphalt mixture, and ultimate gradation of the TLA modified asphalt mixture is finer than previous gradation. TLA modified asphalt mixture has excellent high temperature stability, capacity of moisture-resistance damage and impermeability. So it can be applied to asphalt pavements engineering of expressway in China.

Abstract: In order to reveal the influence of acidic gas SO2 and CaO etc alkali substances which are contained in industrial furnaces smoke to the strength of PSA fiber, tests are made in different acid and alkali conditions, and the changes of its surface morphology were observed by scanning electron microscope (SEM). The results show that: PSA has better acid corrosion resistance than alkali corrosion resistance. Its acid corrosion resistance is similar to the domestic aramid. PSA is better than Nomex in the concentration of 5% H2SO4. Its alkali corrosion resistance is worse than domestic aramid. The retention rate of breaking strength drop to 60.80% and 69.52% respectively after treated in the concentration of 5% H2SO4 for 48 hours and in the concentration of 5% NaOH for 4 hours. The elongation rate decline to 68.14% and 40.22% respectively, and the elongation rate fell to 68.14% and 40.22% respectively. Therefore, the PSA must be dealt against corrosion when used in strong acid or alkali environment.

Abstract: Deformation mechanism maps at 0-883 K and shear strain rate of 10-10-10+6 s-1 were built from available rate equations for deformation mechanisms in pure magnesium or magnesium alloys. It can be found that the grain size has little effect on the fields of plasticity and phonon or electron drag, though it has important influence on the fields of power-law creep, diffusion creep, and Harper-Dorn creep in the maps within the present range of temperature, strain rate, and grain size. A larger grain size is helpful to increase the field range of power-law creep but decrease that of diffusion creep when the grain size is smaller than ~204 μm. Harper-Dorn creep dominates the deformation competed to diffusion creep in the grain size range of ~204-255 μm. The maps include only plasticity, phonon or electron drag, and power-law creep when the grain size is higher than ~255 μm, then the grain size has little influence on the maps. Comparison between the reported data for the Mg-Gd-Y alloys and the maps built from available rate equations, it can be conclude that the maps are an effective tool to predict or achieve a comprehensive understanding of the deformation behavior of the Mg-Gd-Y alloys and to classify systematically their discrepancies in the deformation mechanism. However, differences exist in the deformation mechanisms of the alloys observed by the reported data and that predicted by the maps. Therefore, refinement of the maps from the viewpoint of mechanical twining, DRX, and adiabatic shear are necessary.

Abstract: The research of micromechanism of stress evolvement is presented by analyzing fluctuation and change of surface stress in aluminum alloy thick plate with X-ray diffraction(XRD). From the micro view, a model of “rotation looping and shearing grain” was proposed to analyze and discuss the inhomogeneous distribution of micro-stress in location area, due to inhomogeneity of organization in material. The results present that the inhomogeneity of plastic deformation is direct cause lead to residual stress in plate, and complication of micro-stress distribution results from non-uniformity of organization.

Abstract: From microstructure and technical performance of different fibers, the variation and influence of the different fibers’ properties and parameters on cryogenic properties of matrix asphalt and asphalt mixture were researched and evaluated through BBR and cryogenic trabecular bending tests. Research shows that: the addition of fibers makes the matrix asphalt’s low temperature creep stiffness S increases, creep slope m decreases, namely the matrix asphalt cryogenic flexibility and stress relaxation ability are weakened; cryogenic anti-cracking ability of asphalt mixture is significantly improved through adding different fibers, the order of improving effectiveness: Dolanit AS fiber> ARBOCEL lignin fiber> Basalt fiber; while asphalt content is constant, with the increase of fiber content, the mixture maximum bending strain, strength, deformation of mixture firstly increase and then decrease, the optimal asphalt content of asphalt mixtures and optimal fiber content of three fibers are identified according to the above three indicators’ maximum. Research points out the existed problems that are scope of application and evaluation indicators in BBR test of SHARP, optimal asphalt and fiber content are fully recommended, it provides scientific guidance and practical foundation for actual project.

Abstract: FeS solid lubrication duplex layer was prepared on the surface of 45 steel by ion nitrocarburizing-ion sulphurizing process. The sulphide grains in micron and nano scale and holes distributing equably on the duplex layer. The n-Al2O3 particles in liquid paraffin oil were set into the holes in micron and nano scale of the duplex layer by using vacuum dipping process to prepare the n-Al2O3/FeS solid lubrication duplex layer. Friction and wear performances of the n-Al2O3/FeS solid lubrication duplex layer were investigated to be excellent under different loads and temperatures. The causes are as follows: the solid lubrication function of FeS solid lubrication duplex layer, the “micron nano bearing” function of the nanoparticles embedded in the micron nano pores of FeS solid lubrication duplex layer, and oil lubrication are integrated by nanoparticles/FeS solid lubrication duplex layer and exert synergic lubrication function under high temperature and over loading condition. so the coefficients of friction and volume loss of the n-Al2O3/FeS solid lubrication duplex layer under load 60N and temperature 150°C are 10% and 31.3% lower than those of the FeS solid lubrication duplex layer lubricated by the n-Al2O3 additive, respectively.

Abstract: High-resolution electron backscatter diffraction (EBSD) in scanning electron microscope and transmission electron microscope (TEM) were used to investigate the microstructure of Fe-32%Ni alloy processed by large strain multi-axial forging. The samples were compressed with loading direction changed through 90º from pass to pass at temperature of 500°C and a strain rate of 10-2/s. The results show the microstructure evolution is characterized by full development of almost equi-axed fine grains, not well-developed grain boundaries accompanied by high dislocation density and the existence of extensive extinction contours in the vicinity of grain boundaries, and the structure characteristics indicate that the grain boundaries are in a non-equilibrium state with high internal stresses.

Abstract: Stress in the interface of contacts was calculated applying finite element software/ABAQUS, with which the Ruiz fretting damage parameter was obtained and the location for crack formation was found. A new model for predicting fretting fatigue life has been presented based on friction work. The rationality and effectiveness of the model were validated according to the contrast of experiment life and predicting life. At last influence factor on fretting fatigue life of aerial aluminum alloy LY12CZ was investigated with the model. The results revealed that fretting fatigue life decreased monotonously with the increasing of normal load and then became constant at higher pressures. At low normal load, fretting fatigue life was found to increase with increase in the pad radius. At high normal load, however, the fretting fatigue life remained almost unchanged with changes in the fretting pad radius. The bulk stress amplitude had the dominant effect on fretting fatigue life. The fretting fatigue life diminished as the bulk stress amplitude increased.

Abstract: the wearing of the rolling bearing is actually associated with both randomness and fuzziness. In this paper, we analyze the fuzziness of the experimental data of the wearing life of the rolling bearing and discuss its fuzzy subsets, membership function and fuzzy identification. We take the wearing life of the 102 rolling bearing for example, study the normal fuzzy set and three-parameter Weibull fuzzy set and conduct the identification for the probability distribution. In particular, we also develop an innovative method to identify the experimental data of the wearing life of the rolling bearing.

Abstract: The temperature of thermohydrogen treatment for the testing workpieces respectively was 650°C,750°C,850°C. By turning testing workpieces of different hydrogen content Ti6Al4V alloy, measuring cutting force and surface roughness as well as observing chip morphology, the effect of themohydrogen treatment temperature on machinability of Ti6Al4V alloy has been studied. Results of this experiment indicate that machinability of Ti6Al4V alloy improves with increasing the temperature of thermohydrogen treatment at the range of experimental temperature.