Advanced Materials Research Vols. 634-638

Abstract: Topography and wettability plays an important role to fouling release performance of a coating. Surface morphology and water contact angles (WCA) depending on time of three waterborne polyurethane (WPU) coatings were studied by laser scanning microscope and optical contact angle meter. The results show that WPU coatings with low hard segment content are consisted of hard segment domains, soft segment domains and crack-like non-cohesive regions. With increasing hard segment content, nanostructured micro-phase separated topography is easier to forming, and crack-like non-cohesive regions is reduced. A stable hydrophobic surface in the WPU system can be obtained by drying coating at 60C as well as adding hard segment content to improve fouling release performance of the coatings.

Abstract: A surface alloyed process that adopted ferrous-tungsten and carbon powders as reactants to in-suite synthesize WC reinforcement particles with the assistance of molten carbon steel was attempted in this paper. Results showed that the surface alloyed layer is dense and there are no obvious defects. Microstructures from surface to core are consisted of three different layers, i.e., the top surface alloyed layer, the interim transitional layer and the bottom matrix steel. There are no any WC particles formed in the surface alloyed layer which is consisted of dendrite matrix and inter-dendritical net eutectics and carbides. The net carbides have two types: one is WC or W2C; the other is M7C3. Few large metal tungsten particles are distributed at part bottom of the surface alloyed layer. The microstructure in the transitional layer is consisted of large amounts of pearlites and certain amounts of net carbides.

Abstract: TiBCN coatings were prepared by magnetron sputtering installed with two kinds of target materials (Ti and TiB2) in a mixed Ar, N2 and C2H2 ambient. The results showed that the TiBCN coatings could be successfully obtained by reactive sputtering with Ti and TiB2 dual targets. Raman spectroscopy indicated that TiBCN had similar spectra with DLC, which confirmed with high C content, in the wave range of 1000 ~ 2000 cm-1. The hardness of the coatings would decrease with an increase of N and the sp3 bond in the coatings. The friction coefficient against soda-lime glass ball was decreased from 1.3 of blank WC-Co substrate to 0.35 of the coatings in dry sliding condition.

Abstract: Surface hydrophobic modification of T-ZnOw was experimented with silane coupling agent KH-570(gamma-(methylpropyl acyloxy)trimethoxysilane). It was shown by FT-IR that the whiskers was modified by silane coupling agents molecular compounded with the Zn-OH of whiskers. The effect of grafted modification with KH570 on hydrophobicity of T-ZnOw was characterized with dispersion stability test in an organic solvent and measuring the contact angle between the whiskers on distilled water. The results showed that surface treatment of T-ZnOw with KH570 improves hydrophobicity of whiskers simultaneously, and the modified whiskers have much slower settling rates than the pristine whiskers in the liquid paraffin. The contact angle between the modified whiskers with distilled water is 137.75 degrees, which is a significant increase.

Abstract: Titanium carbide coatings were synthesized by reacting with titanium powders in NaF-NaCl based salt on surface of graphite at 1100-1400 °C in argon (Ar). The effect of temperature of heat treatment on TiC coatings properties was studied. Phase composition and microstructure of the TiC coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray spectroscopy (EDS). The “template-growth” mechanism plays a dominant role in the coating formation process.

Abstract: Dissolution of pyrite by chemical oxidation and bioleaching were studied with using short-term batch experiments. The results show that the rate of oxidative dissolution of pyrite increases with the increasing concentration of ferric in ferric sulfate solutions. With the corresponding in the bioleaching, the leaching rate of pyrite is markedly affected by the Eh of the solution. The ferric/ferrous ratio controls the relative rate of the oxidation reactions involved in the process. Additionally, the leaching rate of pyrite is controlled by the pH. The phase analysis of products indicated that S2- 2oxidation can produce S0 and SO2- 4under these conditions. On the basis of predecessors and using these species，the simplest expected oxidation mechanism is S2O2- 3regarded as the intermediate mechanism during the oxidation process.

Abstract: Through lab experiments and mathematical calculation of non¬¬-reaction nucleus model，dynamic study on lime carbonation has been carried out. The result revels that CO₂ transfer is the limit step of lime carbonation reaction；its activation energy is about 83.15kJ／mol

Abstract: Due to its influence on iron corrosion and involvement in dechlorination reaction, the concentration of H+ is crucial to the reactivity and efficiency of nanosized Pd /Fe. In this study, PCP dechlorination by smectite-templated Pd/Fe was studied and the effect of pH on PCP dechlorination was investigated in detail. The reaction rate constant is critically dependant on the reaction pH over the range 6.0~10.0. The dechlorination rate increases rapidly with decreasing the reaction pH value when the pH is 6.0~8.0. The rate change is up to 3.346 folds with decreasing of per pH unit while it decreases down to 0.3338 when pH is in the range 8.0~10.0. The reductive efficiency of zero-valent iron (ZVI) was further investigated by spiking excess PCP in the reaction system. The maximal reaction efficiency of ZVI for PCP dechlorination attains to 78% when pH is 9.0. The difference between the dechlorination rate and reductive efficiency with respect to reaction pH suggest that ZVI could not be effectively utilized to reduce PCP under acidic condition.

Abstract: The medium carbon steel (C: 0.26%, mass percentage) was deoxidized by Ti alloys, and its features of inclusion and microstructure were systemically studied through the scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS). The results show that the element of titanium in inclusions coexists with manganese, and no single-phase oxides of titanium are observed. Through the statistical analysis, it can be seen that the average size of Ti-contained inclusions is similar to the inclusions without the Ti, and the percentage of large inclusions (>5μm) is smaller in Ti-contained inclusions, which may reduce the harmful effect of inclusions. After etching in 3Vol% Nital solution, it’s found that the Ti-contained inclusions can act as nucleation sits for the intragranular acicular ferrite.

Abstract: Large number of available resource is in the copper slag, which includes oxides of copper and oxides of iron. The total iron in copper slag is usually above 35%, and iron element in copper slag are mainly distributed in olivine phase and magnetic iron oxide minerals. Because minerals in copper slag embedded with each other and the grain of minerals in copper slag are very small, so it is very difficult to recover iron from the copper slag by means of traditional separation technology. Based on the characteristics of copper slag, iron in copper slag can selectively be gathered to magnetite phase through the melted copper slag is processed, and the size of grain of magnetite grows up by adopting appropriate measure to control the reaction temperature. With magnetic separation technology, the magnetite (Fe3O4) can be gotten which contains more total iron.