Advanced Materials Research Vols. 239-242

Abstract: This paper reviews the prospect and research history of the hierarchical porous oxides. Give some preparation methods and application of hierarchical porous oxides derived from wood templates. The selection of plant template, varieties of impregnating agents, different preparation processes and characterizations of compounds are discussed and analyzed.

Abstract: The inhibition effect of N,N-diethylammonium O,O'-di(4-Methylpheny)dithiophosphate (NOPP, [NH₂Et₂][(4-MeC₆H₄O)₂PS₂])against the corrosion of carbon steel in HCl solution was studied by weight loss measurements, electrochemical measurements, AFM and SEM techniques. The studies of weight loss measurements indicate that the NOPP acts as a good inhibitor for the corrosion of carbon steel in HCl solution. Polarization curves indicate NOPP is a mixed-type inhibitor. The adsorption of NOPP on carbon steel surface obeys the Langmuir isotherm, and the obtained standard free energy of adsorption suggests that the chemisorption takes place spontaneously.

Abstract: In order to get a clear picture for describing the growth process of plasma electrolytic oxidation coatings under escalating voltage waveform, the characteristics of PEO coatings formed at different reaction stages were systemically investigated. The morphology and corrosion resistance of the films were studied by scanning electron microscope and potentiodynamic polarization curves. The uniform, semi-transparent and better corrosion resistance of the oxide films on the magnesium electrode surface were formed owe to the extended anodizing time at the initial stage under escalating voltage mode. After sparking occurred, generated ceramic coatings were brokedown, melted, cooled and solidified continuously, so the ceramic coatings were uniform and dense. It also exhibited superior corrosion resistance.

Abstract: With different charging energies, the wire voltages and currents were measured when the molybdenum wire explosions occurred and the coatings were sprayed on the aluminum alloy substrates. The measured voltages and currents were brought into calculating the deposited energies of the molybdenum wires. And the coatings were characterized by observing their cross sections with a Scanning Electron Microscope and testing their thickness, surface roughness and hardness. The results revealed that when the charging energy was higher, the growth rate and value of the deposited energy would be larger, the coating became denser and smoother, and the average thickness and the surface roughness were smaller, while the average hardness firstly increased, and then decreased with the ascension of the charging energy.

Abstract: Novel microwave synthesis cationic hemicelluloses from sugarcane bagasse were obtained by quaternization with CHMAC using sodium hydroxide as a catalyst in microwave synthesis condition. The parameters including the dosage of hemicellulose/CHMAC, the microwave time and the microwave power were optimized and the extent of quaternization was measured by zeta potential. As paper additive, the effect of cationic hemicellulose on bleached bagasse was researched. Then pulp handsheet properties were studied. The results indicated that adding the cationic hemicellulose could increase paper mechanical strengths, and its effect was better than original bleached bagasse pulp. At the dosage of 0.8% on oven dried pulp, paper tensile index, tensile strength, breaking length, burst index and folding endurance can be increased by 43.79%, 36.95%, 33.11%, 17.35%, 33.33% respectively, much better than the paper without the cationic hemicellulose.

Abstract: The hybrid nanocomposite coatings were processed in solution using acid-catalyzed hydrolysis and condensation of precursors 3-Glycidoxypropyl trimethoxysilane (GPTMS) and Tetraethoxysilane (TEOS) forming self assembled nanoscale composite. Coating were applied by dipping 5083 aluminium alloy in sol-gel solutions at several stages and different aging times. Effect of GPTMS-TEOS sol's aging time on thickness, adhesion, and corrosion behaviour of hybrid organic-inorganic GPTMS-TEOS sol-gel coatings have been investigated. The results indicated that thickness of hybrid coatings increased but adhesion decreased with increasing aging time. Adhesion test and electrochemical polarization behaviour reveal that if the coating process was chosen correctly, the coating had a good adhesion strength and corrosion resistance.

Abstract: The flame retardant mechanism of magnesium hydroxide sulfate whiskers(MHSH) is analysed and MHSH and magnesium hydroxide are used to fill high-density polyethylene(HDPE) respectively. The mechanical and flame resistance properties of composite material (HDPE) were also studied in this paper contrastively. The tensile strength and elongation of the compound are increased 2.5% and 36% severally, while MHSH content in weight reaches 20%;at the same time, the oxygen index (OI) of composite materials varies from 17 to 24.2. In contrast, the tensile strength and elongation of the HDPE/ Mg(OH)₂ compound are decreased 6.4% and 48% respectively, OI being 19.6. To sum up, the results of tensile and flame tests of compound material showed the HDPE containing as-prepared whiskers had better overall properties，exceeding that of Mg(OH)₂.

Abstract: The magnetic properties of Fe-Ni alloy nanoparticles with particle size in the range 35-45 nm were prepared by almost simultaneously reducing Fe(II) and Ni(II) solution using hydrazine hydrate as a reducing agent in strong alkaline media for two hours at 80 °C. Chemical composition, crystal structure, morphology, thermal stability and magnetic properties of as synthesized Fe-Ni alloy nanoparticles were systematically characterized by means of XRD, TEM, TG-DSC and VSM. These results indicate that there is a vitally important relationship among particle size, particle morphology, and different mol ratio of FeSO₄ to NiSO₄. The saturation magnetization (M_s). and coercivity (H_c) strongly affected by the composition of Fe-Ni alloy nanoparticles. The hydrothermal reaction is a simple, effective, and low-cost synthetic method to prepare FeNi₃ alloy nanoparticles.

Abstract: To better understand the nature of reactive adsorption of thiophene on Ni/ZnO adsorbent, the effects of ZnO textural structure on the desulfurization activity were investigated. Flower-like ZnO materials were synthesized by hydrothermal homogeneous precipitation method and the corresponding Ni/ZnO adsorbents were prepared by incipient impregnation method. The analysis results showed that both the crystalline sizes and the BET surface areas of flower-like ZnO were better than that of commercial ZnO. The activity evaluations indicated that the Ni/ZnO adsorbents prepared with ZnO possessing a favorable textural structure exhibited good activity of removing thiophene. The evolutions of the main crystalline phases of Ni/ZnO adsorbents before and after reaction confirmed that ZnO played a crucial role in taking up S element and converted it into ZnS in the reactive adsorption process. It was concluded that ZnO with larger surface area and smaller crystal particles resulted in better desulfurization activity, which may be the main reason for the better activities of the Ni/ZnO adsorbents prepared with flower-like ZnO matterials.

Abstract: Agglomeration and poor distribution/dispersion of carbon nanotubes (CNTs) within the matrix remains a major problem in processing homogeneous CNT reinforced metal matrix nanocomposites. In this work, we examine the effect of processing on the dispersion of CNTs in Al6061 and Al2124 alloy based Nanocomposites. Three methods were used to prepare the nanocomposite powders. In the first, CNTs were mixed with the prealloyed powder through dry ball milling. In the second, CNTs were sonicated then the prealloyed powder was added followed by sonication of the mixture and wet milling. In the third, the CNTs were functionalized, sonicated, and then the prealloyed powder was added followed by sonication of the mixture and wet milling. The effect of functionaliztion, sonication and type of milling on the dispersion of CNTs was evaluated.