Advanced Materials Research Vols. 154-155

Abstract: Montmorillonite was introduced into the multicomponent epoxy resin by using the intercalation polymerization. Intercalation effect of epoxy/montmorillonite composite system and the influence of the addition of montmorillonite on the glass transition temperature (Tg), mechanical properties and barrier of H2S to coating under high temperature and pressure conditions were investigated. The results showed that it was easy to intercalate epoxy resin into the organic montmorillonite layers, and the interlayer spacing of Montmorillonite was further swelled. In addition, the epoxy/montmorillonite nanocomposite coating with intercalated/ exfoliated structures were prepared. Compared to pure epoxy coating, the heat resistance and mechanical properties of epoxy/montmorillonite nanocomposite coating were slightly improved, and the barrier efficiency to H2S was substantially increased under high temperature and pressure oil-gas environment.

Abstract: For producing more colorful soybean /flax blended yarns and fabrics and to evaluate the dye-ability of the blends yarn, two types of reactive dyes, containing mono- and bi-functional reactive groups, were studied. On basis of a number of experiments, influences of time and temperature, alkali dosage, addition of promoter are analyzed, the optimum conditions to soybean/flax fibers with Reactive Yellow K-R and Reactive Yellow B-4RFN are defined. Results of performance test indicate that both K-type reactive dyes and B-type reactive dyes have good colorfastness and levels, especially for light to moderate color, and B-types is better than K-types. The colorfastness of the dyed yarns can meet the general requirements.

Abstract: In this article, the effects of galvanizing process parameters, especially cooling rate, on the microstructures of coating was investigated. The microstructures of Al-Zn-Si coating were analyzed by the following methods: surface microstructure, cross-section microstructure, thickness and composition of alloy layer by SEM and its accessories, distribution of each element along depth by glow-discharge emission spectrometer, micro-area elemental distribution image analysis of each element distribution on surface and cross-section by electron probe, crystallization orientation by X-ray diffraction instrument. The results showed that coating was made up of aluminum-rich dendrite, interdendritic zinc-rich phase and alloy layer, that cooling rate affected depth of alloy layer in Al-Zn-Si coating directly, that zinc concentrated in the surface layer of coating and silicon in the alloy layer, while the coating has larger depth it also concentrated in the surface layer, that aluminum-rich dendrite has preferred orientation in the solidification process.

Abstract: Analytical models are presented for investigation of cure dependent stiffness of woven fiber composites. A linear-like correlation is adopted between the material properties and resin degree of cure. Fiber undulation model takes into account the fiber continuity and undulation and has been adopted for plain weave fiber mats geometry modeling. The analysis is performed on a unit cell, which is a representative of the entire fiber mat lamina. The classical laminate theory (CLT) is applied to determine stiffness constants in the infinitesimal region of the composites unit cell. The theoretical models can prediction the changes of stiffness matrices with the degree of cure. A case studies show that the elements of the stiffness matrices showed exponential increase with the resin degree of cure.

Abstract: In this paper, the calculation formulas of the asperity’s deformation related with the surface contact pressure are deduced by using the simplified contact model. Firstly, we assume that the rough surface is composed of a set of cones as asperities, and the cones are arranged in different ways along two directions. Secondly, according to the mechanical analysis of a rigid conical punch on a half-space, the theoretical relationship between the average pressure of the micro contact area and the property parameters of a conical punch is obtained. Meanwhile, the calculation formula of the average pressure is given under the reasonable assumptions, which is related with the asperity’s deformation and the contact pressure. Finally, combining two theoretical relationships above, the quantitative analysis method for micro asperity’s deformation of two rough surfaces in contact is provided by using the average pressure as a connection bridge.

Abstract: The growth morphology and structure of deposits during the initial stages of amorphous Ni-P electrodeposition was studied using atomic force microscopy (AFM), X-ray diffraction (XRD) and transmission electron microscope (TEM). Combined electrochemical and surface analytical measurements showed that the electrocrystallization process follows a three-dimensional instantaneous nucleation and growth mechanism. The structure of the Ni-P deposits progressively changed from polycrystalline to amorphous state with increasing electroplating time. Additional electrodeposition was carried out on amorphous carbon film at potential -650mV (SCE) for 5s in the same bath for plating Ni-P alloy. It was confirmed that the formation of crystal Ni at initial stage of electroplating Ni-P amorphous alloy was not caused by the epitaxial relationship between the crystal Ni and the crystal substrate and there was a nucleation process in the electrodeposition of amorphous alloy.

Abstract: The microstructures and properties of Sn3Ag2.8Cu and Sn3Ag2.8Cu-0.1Ce solder alloys were investigated by means of OM, SEM and EDX and compared to that of Sn37Pb. The results show that the wettability of Sn3Ag2.8Cu-0.1Ce is more favorable, Sn3Ag2.8Cu exhibits poorer wetting behaviour compared to that of Sn37Pb solder; the conductivities of Sn3Ag2.8Cu-0.1Ce and Sn3Ag2.8Cu soldesr are almost 20 percent and 8 percent higher than that of Sn37Pb respectively; the fractography of tensile specimen of Sn3Ag2.8Cu is smooth and light, and is a quasi-cleavage fracture mechanism, whereas that of Sn3Ag2.8Cu-0.1Ce is dark and rough, and has a fibrous pattern, and is a ductile fracture mechanism; the fractography of Sn3Ag2.8Cu-0.1Ce includes more compact and more uniform dimples than that of Sn3Ag2.8Cu, this is cause of the trace amounts of Ce refining the microstructure; brazing with the Cu substrate, the diffusion layer of Sn3Ag2.8Cu solder with Cu substrate includes more irregular IMC compared to Sn3Ag2.8Cu-0.1Ce and Sn37Pb..

Abstract: Directional solidification continuous casting (DSCC) processing is steady directional growth process of Cu crystal. It was influenced by seven parameters, and very easy to be broken for some disturbance. Therefore, random crystals grew. In this paper, location of liquid-solid interface Z was set as control object. And correction disturbance closed-loop control was set as general control planning in DSCC processing. Then fuzzy control was selected as control mode. And control algorithm was designed. The closed-loop control process in DSCC processing was simulated. The simulation results showed that control object could return to safe rang even existing random disturbance. And the control process had good stability. Designed fuzzy control device could satisfy DSCC process requirement.

Abstract: Weld quality control is of great importance in tailored blank laser welding for the purpose of making products at a high quality and high productivity. In general, the controllable parameters are only indirect data on features of the final weld to be made. In this paper, direct correlation between weld concavity and weld process parameters including weld gap and torch offset are discussed based on theoretical analyses and experiments. A direct control model is established according to the analysis of reasons causing weld concavity. This model will improve the quality of laser welding process by accurately controlling the weld geometry in real time.

Abstract: A series of experiment were performed to test the tribological properties of Si3N4 ceramic pair lubricated by emulsions of alkane. The experiment results showed that all alkane are very efficient lubricator for Si3N4 ceramic pair. The straight chain alkanes can perform better than branched paraffin or polycyclic saturated hydrocarbon. When added the liquid paraffin with chlorinated paraffin or Oleic acid, the lubrication property become poor. But added with silicone oil emulsion，the lubrication improve further. Base on the molecular structure of reagents, the causative mechanisms is investigated.