Advanced Materials Research Vols. 189-193

Abstract: The concept of BrIM (Bridge Information Modeling) is proposed and the technical features of BrIM are briefly described. A bridge CAD system based on BrIM concept is developed under the graphic platform of AutoCAD using ObjectARX. Data interface between 3D solid geometric database and each stage of bridge lifecycle is introduced. The essence of BrIM is realized that all informations including geometric data and non-geometric data are stored in the only knowledge database and all informations of bridges in different stages, such as design, construction and service, are obtained in the only database.

Abstract: Effects of TiO₂ on the viscous characteristic of mold fluxes for the stainless steel were investigated by the rotary viscometer, TEM and XRD. The results showed that with the increasing amount of additive TiO₂, the viscosity and solidification temperature of mold fluxes could decrease gradually, and then increase rapidly. The viscosity and solidification temperature of mold fluxes were minimum of 0.30Pa.s (1300°С ) and 1198°С respectively, as amount of additive TiO₂ was 10mass%. The viscosity of mold fluxes could be decreased by the additive TiO₂ which played the role of network modifier, and could be increased by the precipitation of perovskite (CaTiO₃) crystals as amount of additive TiO₂ was more than the critical value. The growth of cuspidine and wollastonite crystals could be restrained, and the precipitation of perovskite and melilite crystals could be promoted by the additive TiO₂. In this study, the solubility of additive TiO₂ was more than 20mass% in mold fluxes at 1350°С .

Abstract: In this paper, a 3-D contact model for anisotropic rough surfaces based on 3-D statistically measurements is established and finite element contact analysis is conducted. The average height of the asperity (h), the average summit distances between two neighboring peaks of asperities (Sx and Sy) are selected as the characterized parameters of the rough surface. Finite element simulation results show that the normal contact pressure has an exponential relation with the normal deformation and an exact linear relationship between the normal deformation and the real contact pressure of the surfaces is obtained. At last, the normal contact stiffness of the joint interface is obtained empirically with the exponential relationship assumption.

Abstract: The permeated grinding wheel was a new kind of grinding wheel, which was permeated by the chemical additives and solid lubricant into the interior gaps of the grinding wheel. Therefore, the grinding wheel can form a lubrication film on the surface of the grinding wheel. This grinding wheel has some good features, such as lower grinding temperature, smaller grinding force, higher life of the grinding wheel, and can prevent the adhesion of chip onto the grinding wheel surface. The experimental results indicate that the ground surface quality and grinding efficiency have been remarkably improved for more hard-to-cut materials.

Abstract: In layer-by-layer EDM milling based on inner jetted dielectric, the dielectric inlet pressure is an important process parameter and has great influence on the machining characteristics. So, numerical simulation of the liquid-solid two-phase flow field in discharge gap is conducted. The simulation results of debris concentration reveal that the debris can be evacuated from the discharge gap in time, which increases the machining process stabilization and improves the machining efficiency. Finally, the effect of dielectric inlet pressure on material removal rate (MRR) and tool wear ratio (TWR) were also researched and discussed. The optimum inlet pressure, which maximized the MRR and minimized the TWR, was found through experiment.

Abstract: In order to research the adhesion of sputtering protective coating of Gd. Gd substrates was coated with 1Cr18Ni9Ti by means of DC magnetron sputtering technology. The characteristics of the film were investigated by scanning electron microscopy (SEM), EDS, SPM and the adhesions of film was tested by tension test. The results show that the films of 1Cr18Ni9Ti are distributed by means of islands when the sputtering was initiated and the grains are like thin fiber. After a few minutes, the films are smooth and perfect, the interferences between 1Cr18Ni9Ti and Gd join together strongly, and the largest strength of adhesion is 24.7MPa when the sputtering density is 966 w/cm2 and the sputtering time is 8 minutes.

Abstract: CrN and CrAlN coating tools were heated and heat-preserved in electric stove to make oxidation experiment. The results were obtained through SEM, EDX and XRD. The results are as follows: The oxidation of CrN and CrAlN coating is induced by the micro-holes which were formed by the diffusion of nitrogen atoms and chromium ions towards the coating surface under sufficient thermal energy. With the incorporation of Al, CrAlN coating showed stronger oxidation resistance as compared to CrN. The dense mixture of Cr₂O₃ and Al₂O₃ makes oxygen diffusion through the film difficult and then oxidation and decomposing are alleviated effectively, therefore CrAlN coating can remain high oxidation resistance and high hardness after high temperature which make this coating tool be competent for high speed machining of the hardworking materials. In addition, the failure of the coating is primary induced by oxidation and the different expansion coefficients between coating and substrate.

Abstract: Poly-γ-glutamic acid (γ-PGA) is a kind of water-soluble and biodegradable polymer, as a potential targeted biopolymer that can be refined from biomass directly. In this work, the effect of environmental parameters on γ-PGA formation by Bacillus licheniformis is investigated . The influence of culture temperature, pH and culture time on cell growth, γ-PGA production and molecular weight, polymer stereochemistry are determined. The γ-PGA yield is higher(30.13g/L) at culture temperature 37 , pH 7.0. Alteration of the medium pH, temperature, culture time and aeration had little to no significant effects on the product quality as measured by stereochemical composition. But alteration of the medium pH, temperature, culture time and aeration have obvious effects on the γ-PGA yield and molecular weight, increasing the biomass and γ-PGA yields. Under the optimal environmental conditions yields of γ-PGA in excess of 36g/L is obtained in submerged culture. Finally, the large-scale fermentation of γ-PGA production was successfully scaled up to a 100-l fermentor, with the highest γ-PGA productivity for over 57.5 g/l.

Abstract: A SiC ceramic coating for high temperature and anti-oxidation was prepared by high temperature reaction and PVD methods inside industrial synthetic furnace of SiC. Its phase composition and microstructure were characterized by using XRD, SEM,and its high temperature anti-oxidation property were studied by isothermal oxidation tests.The results showed that the coating is composed of mainly α-SiC and β-SiC,the coating is uniform, compact, perfect grain growth, without crack, closely with the C/C materials,the thickness is about 600μm. After 10h oxidation in air at 1773 k the weight loss of the coating was only 0.3%,which implies that the coating has excellent anti-oxidation ability.

Abstract: Friction is a phenomenon caused by relative motion, which can be used to absorb vibrational energy. The influence of friction on vibration responses of structures is complex due to the complicacy and nonlinear of the friction itself. In this paper, a 3-DOF spring-damper model with/without friction force was studied to expose how the friction governed the vibratory responses. Several popular friction models were reviewed and LuGre Model was used in this paper. The vibration properties under sine excitation and random were simulated by the Matlab Simulink Software. The results showed that friction absorbed vibration well and vibration damping was rapid. The characteristics of friction influence resulted from comprehensive functions of all factors, such as types of excitation, excitation amplitude and frequency and the location of friction.