Advanced Materials Research Vols. 146-147

Abstract: Using TiO2 and ZrO2 as compound nucleation agent, serials Li2O–Al2O3–SiO2 (LAS) glasses containing different content of P2O5 were prepared by conventional melt quenching technique and subsequent converting to glass–ceramics. The influence of P2O5 content on viscosity of LAS glasses was investigated in the temperature range from the softening point to melting temperature. DSC was undertaken to analyze the change of characteristic temperature Tg, Tc and Tp. Thermal expansion coefficient (TEC) of matrix glass and glass-ceramic containing different P2O5 were measured. The results show introducing P2O5 effectively decreased the melting temperature and viscosity of LAS glasses. TECs of the matrix glass and glass-ceramic range from 4.1×10-6 °C -1 to 5.3×10-6 °C -1 and from -0.2×10-6 °C -1 to 1.2×10-6 °C -1, respectively. XRD analysis indicates that β-spodumene is the main crystalline phase in the P2O5 doped LAS glass-ceramics, resulting in the low thermal expansion coefficient of the glass-ceramics.

Abstract: The transformation of tempering for quenched steel corresponded to complicated process of phase transformation, and mechanical properties of quenched-and-tempered steel were related to the phase transformation. In practice, hardness test was adopted to judge whether the properties of tempered-parts qualified because of its facility. Numerous researches indicated that, there existed correlativity expressed by different function forms between tempering hardness of quenched-steel and its tempering parameters. However, considering physical metallurgy of tempering process, the adoption of double-exponential function would help to describe regularity of hardness changing more exactly for quenched-steel during tempering process. Additionally, results of hardness tests for isothermal tempering and molding/simulation researches have shown that, the model of double-exponential function, which can reflect decline law of tempering hardness for quenched-steel, would provide basis for optimization design of tempering parameters, performance prediction of tempered-parts, and energy-saving heat-treatment on tempering process.

Abstract: In order to improve the computing precision and computing efficiency of strength of woven composite material, the strength of woven composite material based on multi-scale finite element method (MsFEM) is simulated. The periodical boundary conditions are applied to the finite element method analyses to ensure stress continuous and strain continuous on boundary surfaces. The method can efficiently capture the large scale behavior of the solution without resolving all the small scale features by constructing the multi-scale finite element base functions that are adaptive to the local property of the differential operator. The characteristic difference between MsFEM and the conventional finite element method is attributed to base function. The applications demonstrate that the advantages of the multi-scale finite element method for numerical simulation of strength problem of woven composite material, i.e. significantly reducing computational efforts, and improving the accuracy of the solutions.

Abstract: C3S is one of the most important mineral phases in silicate cement clinker; alternative ions could be solidified into C3S crystal lattice. Therefore, the research on solid solution mechanism was studied, which was about C3S doped with ions, Meanwhile, the achievement of this paper could be taken as a guidance for cement clinker industry. The effect and solid solution mechanism of Co2O3 during C3S formation were studied by means of chemical analysis, XRD and phase diagram analysis. The results show that when Co2O3 additive was less than 1.5% in mass, the content of f-CaO increased with the increase of Co2O3, and the formation rate of C3S was accelerated by Co2O3; when Co2O3 addition exceeded 1.5%, the content of f-CaO decreased with the increase of Co2O3.By the least square method and defined f-CaO, the molecular formula that Co2O3 solidified in C3S could be deduced: (Ca3-0.86x Co0.86x) (Si1-0.14xCo0.14x) O5 (x=0.0209).

Abstract: The morphology and structure of Broussonetia papyrifera(BP) bast and fiber were investigated by SEM, OM, FT-IR and X-ray analysis, and chemical composition of BP bast was analyzed. The results show that the cellulose content in the BP bast can be as high as 63.76%. BP fibers arrange parallel in the bast, which are linked by pection. The cross-section of PB fibers are irregular round with lumens that are almost invisible in the completely mature fibers. The crystallinity of the fiber could reach 83.26%. Most impurities such as hemi-cellulose, lignin, pectin could be effectively removed by degumming, while cellulosic structure is not changed. BP fiber has good mechanical properties, but the single fiber is too short to spin alone.

Abstract: In the present work, rapidly solidified Al-21Si-0.8Mg-1.5Cu-0.5Mn alloys strips was prepared by melt-spinning method. The microstructures, phase and morphology characteristics of the experimental alloy were characterized by means of scanning electron microscopy, transmission electric microscopy. The results show that the microstructures are changed obviously compared with conventional condition. The nucleation and growth of primary silicon are suppressed and primary silicon can not deposited, meanwhile, α-Al phase is nucleated which prior to eutectic. The microstructures of the rapidly solidified alloys are composed of primary micro-nanostructure α phase and feather-needles-like (α+Si) eutectic which set in the α phase. The mechanism of formation for microstructures of melt-spinning Al-Si alloy have also been discussed.

Abstract: Electrospark deposition (ESD) is a promising process to produce hard and wear-resisting coating on metallic substrates. Fe–Cr–Ni–Si–Mo–W–B–Co–Al alloy rods were used as electrode to produce coatings onto a high carbon cast steel roll substrate. Different parameters were used and the coatings have an average thickness of～80 μm, which are metallurgically bonded to the substrate. The microstructures of the coating prevail in nanosized grains and amorphous structures. The primary phases of the coating contain C0.055Fe1.945，(Fe,Cr)7C3，Fe7Mo3 and Al0.99Fe0.99Ni0.99. The maximum microhardness value of the coating is about 1837.4 HV. The study reveals that Fe-based ESD coating has a better quality and has a high hardness on the cast steel roll.

Abstract: The tribological properties of a high base value sodium sulfonate-modified nano carbonate sodium as lubricating oil additive were introduced in this paper, and its antioxidant collaboration property with ashless antioxidant was evaluation by using pressure differential scanning calorimetry(PDSC). The results show that the product possesses good tribological properties, thermal stability, and a good synergistic antioxidation effect with ashless antioxidant, and mainly to increase oxidation free energy of base oil.

Abstract: A pulsed electric current (19 kHz, 0-8 volts) has been applied to a molten Fe-0.5C-1.5Mn alloy to investigate its effect on the microstructure and the distribution of carbon and manganese. It has been shown that the pulsed electric field can improve the microstructure from a coarse banded structure to a compact acicular structure by increasing the pulsed voltage from 4 volts to 8 volts. The pulsed electric treatment also has an effect on the C and Mn distribution with a tendency for C and Mn to migrate to the cathode.

Abstract: Cyclic plasticity and viscoplasticity of a nickel-chromium alloy have been described using the Chaboche unified constitutive model. Experiments have been developed to obtain the full cyclic stress-strain and stress relaxation data at 450°C. A step-by-step method has been used to obtain the initial material parameters, while a non-linear least-square approach has been used to obtain the optimised material parameters. Satisfactory results have been obtained for the simulation of the transient and steady state cyclic stress-strain and stress relaxation behavior.