Advanced Materials Research Vol. 645

Abstract: Overbased calcium sulfonate complex greases have excellent friction and wear properties and have been widely used in metallurgy and mining equipment. The effects and tribological performance of molybdenum dialkydithiocarbamate (MoDTC) and ionic liquid 1-(2-hydroxyethyl)-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([C2OHMim][NTf₂]), 1-(2-hydroxyethyl)-3-hexylimidazolium bis (trifluoromethylsulfonyl) imide ([C2OHHim][NTf₂s]), added in overbased calcium sulfonate complex grease as additives were investigated by using reciprocating ball-on-disk sliding friction tester. The results showed that the two kinds of additives with a certain range of concentration could improve the tribological properties of greases.

Abstract: In this paper, dialkyl dithiocarbamate molybdenum (MoDTC) as a friction reducing additive was used for compound synthetic lubricant. The tribological properties of MoDTC were investigated using the MFT-R 4000-high-speed reciprocating friction and wear tester. And the results showed that the PAO +10wt% PEG +0.3wt% MoDTC have the best friction reducing and anti-wear properties.

Abstract: To improve carboxymethylation reaction, chitosan as reactant was activated to change its morphology and compact structure. The crystallization properties of chitosan before and after activation were characterized by X-ray diffraction analysis. Different preparation methods were compared using activated, powdery or flake chitosan as reactants, respectively. And the influences of reaction time and temperature on the yield, the intrinsic viscosity and the degree of substitution of carboxymethyl chitosan were also investigated. We found that, the activation treatment changed the crystallization properties of chitosan, which greatly accelerated the subsequent carboxymethylation reaction; and higher yield of carboxymethyl chitosan with considerable intrinsic viscosity was obtained under the reaction conditions of a shorter time and a milder temperature.

Abstract: Capturing carbon dioxide (CO2) by forming hydrate is an attractive technology for reducing the greenhouse effect. The most primary challenges are high energy consumption, low hydrate formation rate, and separation efficiency. In order to solve the problem of slow formation rate of gas hydrate, the effects of sodium dodecyl benzene sulfonate (SDBS), hexadecyl trimethyl ammonium bromide (CTAB) and polyethylene oxide - polypropylene oxide - polyethylene oxide triblock copolymer (P123) on the formation of carbon dioxide hydrate have been investigated.The results show that CTAB, SDBS and P123 can reduce phase equilibrium point of CO2 hydrate. The lower pressure of hydration reaction system ,the larger induction time of CO2 hydrate reduction.Maximum promotion effect of SDBS was observed at 700 mg / kg which was comparable with that of CTAB at 300 mg / kg and P123 at 500 mg / kg. The study has a certain significance to improve the rate of hydrate formation.

Abstract: Doping magnesium ferrites (MgFe2 O4) with Mn, Co and Ni, which were synthesized by sol gel method using citric acid and polyvinyl alcohol (P VA) and calcined at 500oC, showed interesting electrochemical featur es based on their cyclic voltammetric (CV) characteristics using 5 µL ferrite – poly vinylidene fluoride in ethano l deposited on a screen printed carbon electrode (SPCE) in a mixture of 1.0 M KOH and ferricyanide solution recorded with a scan rate of 0.02 Vs -1. The Mn doped magnesium ferrite (x = 0.9) showed the most remarkable CV performance over other doped element (Co and Ni) and un-doped magnesiu m ferrites. The surface morphology of doped ferrites was studied by applying a field emissi on scanning electron microscope (FESEM) in conjunction with an energy dispersive X-ray spect roscopy (EDX) analysis. The results revealed that Mn posed the highest percentage on the surface ( ≈ 21.5 %), followed by Co (≈ 19.5%) and Ni ( ≈ 6.7%) with respect to x = 0.9 of M0.9Mg0.1Fe 2 O4 (M = Co, Mn and Ni) at 500oC calcination. The study showed the possibility of yielding semi conducting ferrites using own fabricated magnesium ferrite and its metal doping.

Abstract: Since CuInSe₂ (commonly called as CIS) materials has become one of most important photovoltaic materials, they are investigated with optical spectroscopies in this paper. The crystal structure, surface microstructure morphology and composition of the samples are analyzed in XRD and SEM with EDX, and the surface electronic state and optical properties of the samples are characterized in X-ray photoelectron spectroscopy (XPS) and Ultraviolet-visible Spectrum instruments. The results show that CIS phase is very uniform, some impurity phases appear in the samples， the atomic distributing percentages of the surfaces of bulk samples are very consistent in the composition ratio forming the crystal phases of the samples, and the atomic electrons are more active than ones in the relevant elements. Furthermore, the thin film of the sample has high solar energy absorptivity, and is suitable for to be manufactured as solar cell.

Abstract: Nanocrystallite powders of 5 wt% Sm3+ added Mg-Cd ferrite samples were prepared by oxalate co-precipitation method. XRD, SEM and FT-IR techniques were used for characterization of the samples. The XRD reveals cubic spinel nature with secondary phase (SmFeO3). The crystallite size lies in the range of 28.69 to 32.66 nm. All the Sm3+ ions added samples are humidity sensitive at low humidity range 40 to70 %RH. The electrical resistivity of Sm3+ ions added samples decreased by four orders of magnitude, when %RH increased from 40%RH to 90 %RH. The response and recovery time of all the samples are 160-290 sec. The shorter response time was observed for Sm3+ added Cd ferrite sensor.

Abstract: Dry shake screeds are characterized by high durability. It is a modern way of improving the mechanical and aesthetic properties of concrete floor surfaces. It is the so-called “wet-on-wet” method – i.e. a method of applying cement mixtures for floor screed. Stirred cement mixture is spread, in the prescribed thickness, onto the setting fresh cement mixture surface that was arranged and compacted before.

Abstract: The different nano-scale metal-organic frameworks MIL-53(Cr) were synthesized under solvothermal conditions.The experiment was used Cr(NO3)3.9H2O,terephthalic acid,HCl and H2O to react by adding a Sodium Dodecyl Sulfonate and octadecyl trimethyl ammonium chloride . It was characterized by XRD,HRTEM,and BET to obtain relevant information of compose,structure morphologies,and huge BET surface areas.

Abstract: The mechanical properties of concrete with composition of scrapped rubber tyre crumb replacing part of the fine aggregates were investigated. The testing method of the mechanical properties was executed according to . Many groups of crumb rubber concrete specimens are manufactured in different kinds of size and amount of rubber chips. The powder rubber and crumb rubber were mixed into C35 plain concrete, by the volume rations of 0%, 20%, 40 %, 60%, 80% and 100% of the fine aggregates, to investigate the influence of size and amount of rubber chips on the mechanical properties. The results of test indicate: the cubic compression strength, the tensile splitting strength and the strength of rupture decreased with the increase of rubber admixture. But there are some remarkable properties which is difficult to attain on ordinary concrete, such as better cracking resistance, better deformation property, minor density and so on.