Advanced Materials Research Vols. 79-82

Abstract: Controlling the shape of cBN has been met with limited success. This work mainly reports a hydrothermal route to synthesize cBN nanocubes with oriented growth along [100] direction. XRD, TEM and SEM are applied to characterize the structure properties. Regular cubes of cBN have perfect quality and good uniformity. The square symmetry illuminates that cBN cube is a single crystal bounded mainly by the less stable {100} facets. This special morphology is determined by the ratio(R) between the growth rates along [100] and [111] direction.

Abstract: Interface stability has been the subject of extensive investigation by the scientists working in the field of micron or nanometer materials for centuries and the control of the colloidal properties and stability of particle dispersions is of significant importance in the manufacture of high quality water-based dispersions or solvent-based systems. The waterborne dispersion of C.I. Disperse Yellow 64 requires the use of dispersant additives. By the reaction of C.I. Disperse Yellow 64 with poly(oxyalkylene)-amines, a series of dye-polyether derivatives, supposed to be used as dispersants for parent dye dispersions, was synthesized and subsequently characterized by amine titration, SEC and 1H NMR. The polyethers chosen are polyoxyethylene-polyoxypropylene diblock coploymers with different molecular weights and degrees of hydrophilicity/hydrophobicity in the backbones. The influence upon adsorption of dye-polyether derivatives on the dispersion behavior of parent C. I. Disperse Yellow 64 has been investigated. A range of experimental methods including adsorption isotherms, dispersion stability test, and particle size measurements were used to assess the dispersion effect of the dye-polyether derivatives. Adsorption of dye-polyether derivatives onto the parent dye surface is little affected by the molecular weight and increases with the increasing hydrophobicity of the polyether. The dispersion stability of the parent C.I. Disperse Yellow 64 dispersions has considerably been improved by the presence of all the dye-polyether derivatives. In particular, the dye-polyether derivatives exhibited excellent dispersive capacity for the dispersions even at a dye to dispersant weight ratio of 10:1, which largely reduced the dispersant demand compared with the commercial dye. This new strategy of the dye-polyether derivative as dispersant for its parent dye will result in significantly alleviating the environment pollution from dyeing effluent and is not only expected to be applicable to dispersion of other water-insoluble dyes in aqueous media, but also a new promising candidate for the stablization of micron or nanometer materials.

Abstract: The hybrid membranes have been prepared using polyethersulfone (PES) as membrane matrix material and cerium-loaded Y-zeolites (CeY) particles as adsorptive functional group for gasoline desulfurization. The structures of hybrid membrane have a significant influence on membrane performance and adsorption desulfurization process. In this study, the effects of dope composition and membrane formation conditions including coagulation bath composition and its’ temperature on membrane structures were investigated in detail. The SEM results showed that air-side surface of the membrane were a dense layer structure, cross-section of the membrane great changes of the structure present when change the dope composition and membrane formation conditions. From the SEM photos of membrane at glass-side, it can be seen that the inorganic particles were tightly held together within the porous polymeric matrix. The appropriate structures of inorganic/organic hybrid membrane adsorbents can be got by regulating dope composition and membrane formation conditions. The maximum adsorption capacity was 21.6mg S/g membrane, which should have the potential to be used for the deep desulfurization of gasoline.

Abstract: Fe3Al intermetallics with different Al contents were prepared by mechanical alloying and hot pressing. The phases and dry sliding wear behavior were studied. The results show that Fe3Al bulk materials are mainly characterized by the low ordered B2 structure. The wear resistance increased with increasing Al content, with the lowest volume loss of Fe-32Al and irregular value of Fe-30Al. There were obvious differences in wear mechanisms of sintered Fe3Al under different testing conditions. Under lower loads plastic deformation occurred on the wear surface and the wear performance is mainly particle abrasion, the characteristics of which are micro cutting and furrows. With higher loads, the stress concentration led to rapid crack propagation and eventually the fatigue fracture, which was characterized by brittle split of material.

Abstract: Accelerated carbonation is a new technology of materials preparation, which may have potential for the treatment of industrial solid residues and the sequestration of CO2, an important greenhouse gas. In this study, accelerated carbonation was used to recycle steelmaking slag and sequestrate CO2 to manufacture building materials. The experimental results show that the strength of specimens increases along with the increase of carbonation degree. Moisture content, carbonation temperature and curing time have significant effects on the degree of carbonation, and carbonated specimens have larger weight increase and compressive strength increases under the condition of moisture content 12.6%，reaction time 117 min and reaction temperature 361 K. The SEM and XRD analyses indicate that dogtooth like CaCO3 crystals appear on the surface of carbonated aggregate specimens. Strength and soundness test shows that steelmaking slag building materials have higher strength and eligible soundness after accelerated carbonation.

Abstract: The hot bands of non-oriented electrical steel were cold rolled by asymmetric rolling with speed ratio of 1.125 as well as conventional symmetric cold rolling to investigate the effects of cold rolling mode on through-thickness texture variation. Asymmetric rolling shows a marked weakening effect on α fiber (RD//<110>) running from {001}<110> to {112}<110> through sheet thickness, especially at the side contacting with faster roll. Asymmetric rolling increases {111}<112> component while decreases {111}<110> component through sheet thickness except for the surface layers. The through-thickness texture variation due to asymmetric rolling was explained in terms of shear strain distribution.

Abstract: Tensile and compressive deformation and damage behaviors of Al6XN super-austenitic stainless steels were examined at different strain rates. The deformation and fracture surfaces were characterized by scanning electron microscopy (SEM). It was found that the uniaxial deformation (tensile or compressive) behaviors of Al6XN stainless steel shows a low strain rate sensitivity over the range of 10-4s-1 - 10-2s-1. The tensile and compressive yield strengths measured are nearly comparable. The steel shows a good tensile plasticity. Dislocation slip deformation is the main characteristic of uniaxial deformation. All fracture surfaces induced by tensile deformation at different strain rates can be divided into two parts, i.e., fibrous zone and shear lip zone. The fibrous zone consists of dimples with a bimodal size.

Abstract: The temperature dependence of resistivity of liquid Bi33.3Ga66.7 and Bi12Ga88 alloys was measured. Anomalous negative deviation of electrical resistivity of liquid alloys was found near critical temperature. Analysis in terms of the calculating equation for resistivity of liquid alloy suggests that, besides SCC(0), the pseudopotential matrix element and alloy composition still serve as crucial factors in scattering function. That is, concentration-concentration fluctuation in the long-wavelength is not necessarily induced an increase of resistivity of liquid alloy near critical temperature.

Abstract: The mechanics behavior of connecting frame in aircraft composite cabin under static load is researched by three-dimensional finite element analysis. After obtaining the stress distribution, a progressive damage method is adopted to predict the structure strength of the connecting frame. The stiffness and strength are simulated. Furthermore, the damage onset and failure mode are described. The numerical results illustrate the analysis provides insight into the structural strength and distribution of stress and highlights areas requiring further structural design.

Abstract: The paper presents the results obtained when using Mannich bases (and derivatives) as corrosion inhibitors in saline environment, for different types of steels, with various alloying elements. The Mannich basis (ketonic combinations with naphtenic and nitrogen containing rings) were synthesized as such (polar) and as chlorhydrates (ionic) and used in corrosion experiments, in concentrations varying from 0….1300 ppm. The corrosion experiments were performed by potentiodynamic polarization studies. Based on the polarization curves, the corrosion current density and rate were calculated. The inhibitor efficiency was evaluated and based on these values the protection mechanisms was discussed.