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排序方式: 共有177条查询结果,搜索用时 15 毫秒
51.
Mohamad Ali Fulazzaky Nurdin Ali Haryanti Samekto Mohd Imran Ghazali 《Metallurgical and Materials Transactions A》2012,43(11):4185-4193
Nitrogen ion implantation is one of the surface modification techniques used for increasing corrosion resistance of commercially pure titanium (CpTi). The nitrogen ion implanted CpTi in various doses markedly changes the corrosion resistance. Still the effect of nitrogen ion implantation on the CpTi at different energies needs to be verified. This study uses different methods to assess the CpTi surface properties after nitrogen ion implantation in various doses and energy. Surface hardness of the CpTi increases with an increase of the dose and decreases with an increase of the energy. The precipitation of the TiN increases with an increase of the nitrogen dose, and no formation of the Ti2N phase clearly appears. Corrosion resistance of the CpTi specimens can be upgraded to some extent after their surfaces are modified, implanting nitrogen ions at 100?keV by increasing dose. The optimum surface properties of the implanted CpTi are analyzed to contribute to materials science technology. 相似文献
52.
This study focuses on the effects of powder size and Ni–Al bonding layer on the electrochemical behaviour of plasma-sprayed Al2O3-13% TiO2 coating in fresh tropical seawater. The presence of the metallic bonding layer reduces the coating porosity and increases the surface roughness for both microparticle and nanoparticle coatings. The nanoparticle exhibits better corrosion rate of 1.9×10−6 mmpy compared to the microparticle coating, with a corrosion rate of 3.05×10−6 mmpy. However, the presence of the metallic bonding layer increases the corrosion rate for both micro and nanoparticle coatings. The corrosion mechanism for the coating with and without the metallic bonding layer is discussed in detail. 相似文献
53.
Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm2 using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si. 相似文献
54.
Molecular Weight Determination of Palm Olein Polyols by Gel Permeation Chromatography Using Polyether Polyols Calibration 下载免费PDF全文
Mohd Azmil Mohd Noor Vahid Sendijarevic Seng Soi Hoong Ibrahim Sendijarevic Tuan Noor Maznee Tuan Ismail Nurul ‘Ain Hanzah Norhayati Mohd Noor Kosheela Devi Poo Palam Razmah Ghazali Hazimah Abu Hassan 《Journal of the American Oil Chemists' Society》2016,93(5):721-730
Natural oil polyols have been intensively developed and successfully used for the production of various polymers, notably polyurethanes. The need to access the average molecular weight (MW) and the MW distribution (MWD) has led to the efforts to have a precise and reliable determination method. A series of commercial polyether polyols, with well‐defined MW, was used as a gel permeation chromatography (GPC) calibration standard to determine the MW of palm olein polyols. This GPC analysis was compared to the one calibrated against the commercially available polystyrene (PS) standards and to the number‐average molecular weight (Mn) obtained via vapor pressure osmometry (VPO) technique. For example, the Mn obtained for palm olein polyol E‐135 calibrated against polyether polyols was 2,537 Da, which was closer to the Mn via VPO (1,618 Da), than the Mn obtained using PS as calibration standards (3,836 Da). Hence, this GPC analysis using polyether polyols as calibration standards can offer reassured determination of MWD of palm olein polyols. 相似文献
55.
T. Haryati Y. B. Che Man H. M. Ghazali B. A. Asbi L. Buana 《Journal of the American Oil Chemists' Society》1998,75(7):789-792
The triglyceride (TG) composition of palm oil is normally determined by high-performance liquid chromatography (HPLC). The
HPLC chromatograms indicated a good separation of most of the TG components in the oil. The TG can be classified based on
either the TG groups, i.e., triunsaturated, monosaturated, disaturated, or trisaturated, or the number of double bonds, i.e.,
zero, one, two, three, or four double bonds. The more unsaturated the fatty acid, the greater the iodine value (IV). Therefore,
it is hypothesized that the IV of an oil can be determined based upon the TG composition of the oil. Based on the TG groups,
stepwise regression analysis showed that the areas of the disaturated, trisaturated, and triunsaturated TG peaks could predict
the IV with a coefficient of determination (R
2) of 0.990. The regression based on the number of double bonds yielded a good regression equation with R
2=0.992. The important variables were the peak area of the fatty acids that contained zero, one, two, and three double bonds.
This study concludes that the TG composition can be used to predict the IV of palm oil. The best prediction model is obtained
by using the number of double bonds in the TG as the independent variable. 相似文献
56.
57.
I. C. da Cunha Lima L. Loureiro da Silva M. A. Boselli X. F. Wang A. Ghazali 《Journal of Superconductivity》2003,16(2):283-287
It is shown that spin-polarized currents occur in metallic and ferromagnetic Ga1–x
Mn
x
As/GaAs multilayered structures, as a result of the magnetic interaction between holes and the Mn ions. The magnetic layers act as potential barriers for holes with spins aligned parallel to the layer magnetization, and as potential wells for the inverse spin polarization. In the case of currents in-plane, holes with spin parallel and antiparallel to this magnetization move in different regions. By choosing properly the magnetic and the nonmagnetic layers widths, a spin-polarized transport with a difference of an order of magnitude on the mobilities for each spin polarization is predicted to occur. Spin-polarized minibands are also shown to occur in a superlattice based on the same structure. We calculated the dependence of the spin polarization with the superlattice parameters, and we discuss how this polarization affects the Bloch miniband transport in such ferromagnetic superlattice. 相似文献
58.
We present results for the single-particle relaxation time of the spin-polarized two-dimensional electron gas in Silicon-MOSFET systems at zero temperatures. Spin-polarization is produced by the application of a parallel magnetic field. The single-particle relaxation time was measured with the Shubnikovde–Hass effect and is in good agreement with our theoretical results. 相似文献
59.
The reactivity of 4-nitrophenyl esters has been studied against an optically active microgel copolymer containing hydroxamic acid pendant groups. Saturation phenomena are observed in the kinetics consistent with formation of a complex followed by reaction of the ester in the complexed species. The polymer discriminates between R- and S-forms of a chiral substrate in both complexing and catalytic steps. The data are consistent with the existence of chiral spaces in the microgel bead which accept the chiral substrate. The selectivity of the polymer for the chiral substrate (α ~ 2) compares favourably with that shown by conventional chiral chromatographic supports. 相似文献
60.