Advanced Materials and Engineering Structural Technology

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作者: Min Jung Kim, Dong Bok Lee
摘要: The nickel-iron-chromium-based alloy, Incoloy alloy 800, was corroded at 600, 700 and 800 °C for 10-70 h under 1 atm of total pressure in three different atmospheres, viz., 1 atm of N2, N2/H2O, and N2/H2O/H2S-mixed gases. The corrosion rates always increased with addition of H2O and, much more seriously, with the addition of H2S gas. In N2 and N2/H2O gases, oxidation prevailed. In N2/H2O/H2S gases, sulfidation dominated. The corrosion resistance increased in the T22 steel displayed better resistance to oxidation and sulfidation than Fe-2Mn-0.5Si steel, owing to the presence of Cr. Strong enrichment of Cr and the presence of Ni and Fe were noticeable in the inner scale. Chromium sulfidized to FeCr2S4 in N2/H2O/H2S gases, which was responsible for the enhanced sulfidation resistance of T22 compared with Fe-2.0Mn-0.5Si steel.
作者: Francesca Scalisi, Cesare Sposito
摘要: The potential for architecture offered by natural materials in terms of comfort, reduction of embodied energy and energy-saving in the operational phase, dictates in-depth research that might highlight advantages and contribute to improving their characteristics. This research focuses on earth bricks and, in particular, a type of brick made from unfired clay, known as adobe. The aim of the research is to verify improvements in performance of adobe with the aid of nanotechnology. The adobe mixture was prepared with water, soil (from Sicily) and LAPONITE® as a stabilizer. The adobe bricks were subjected to tests of resistance to compression and flexion, resistance to abrasion, capillary absorption of water and resistance to impact. The results may be deemed positive, in particular those relating to resistance to compression. Further research will be necessary, especially with regard to problems of water absorption.
作者: Wei Liang Shi, Xiu Ting Wei, Wei Zhang, Zhi Gang Wang, Chuang He Dong, Shuai Li
摘要: Carbonous material always promotes the development of human being’s civilization. The diamond-like carbon (DLC) is one of the new kinds of materials. In the past fifty years, DLC has reached the level of semi-industrialization. From the unintentional discovery of DLC to the booming study all over the world, and then to the wide use in various fields, DLC has become a symbol of the era. In order to study the relationship between the structure and properties of DLC, researchers have been working on its classification and puting forward its theoretical model. Preparation technologies of DLC have been improving continuously. Nowadays there are some popular technologies such as the unbalanced magnetron sputtering technology, the electron cyclotron resonance radio frequency technology, the femtosecond laser technology, and the meshed plasma immersion ion deposition technology. The application field of DLC has expanded from simple life products to the field of machinery precision cutting tools, precision molds, medical devices and implants, and the aerospace field. Although DLC has developed a lot in the area of industrial application, there are some problems about its connection between technological parameter and performance. In this paper, the development history, structure, preparation methods, development status and the research prospects of DLC coatings are introduced in detail.
作者: Xiao Qian Fu, Yang Li, Zhi Ming Li, Chun Wei Zhang, Xiao Hui Wang
摘要: To characterize the properties of the as-grown AlxGa1-xN material for producing high property AlxGa1-xN photocathode in ultraviolet (UV) detection, the Ar+ sputtering and X-ray photoelectric spectroscopy (XPS) scan are performed. XPS spectra indicates that although processed with chemical solutions, AlxGa1-xN still contains large amount of carbon and oxide on the surface, which can be completely removed by Ar+ sputtering within few minutes. Ga3d and Al2p curves show that there are other compounds of Ga and Al on the surface but both become very concentrated when sputtering continues. The proportion of Al increases and that of Ga decreases gradually from surface to AlN bulk, which testify the graded band gap profile of the AlxGa1-xN sample. There is always a very slight amount of oxygen in the AlN layer, which is regarded as native element during material growth. At the interface of AlN and sapphire, an abrupt transition appears which can influence the properties of the AlxGa1-xN photocathode when it works with the transmittance mode
作者: Xiang Xiao, Hong Li, Jun Tie, Jing Lu
摘要: We study structural, stability, electronic and magnetic properties of zigzag-edged BC2N nanoribbons (ZBC2NNRs) with H-termination in the view of first principles calculations. Four kinds of edge arrangements are considered, labeled as B-C, N-C, N-B, and C-C. Interestingly, we find these four types of H-terminated ZBC2NNRs have various electronic structures. The half-metal and semi-metal are obtained depending on the edge atom alignment. The B-C and N-C ZBC2NNRs with H-termination are half-metals with antiferromagnetic (AFM) ground states. The magnetic moments of the antiferromagnetic (AFM) state always prefer to locate at the ribbon edges. However, the N-B and C-C ZBC2NNRs show spin-unpolarized semi-metallic behaviors at ground states. Our results suggest that the H-terminated ZBC2NNRs can be a promising candidate material in nanoelectronics and nanospintronics.
作者: Alexey Zaikovskii
摘要: The carbon material was synthesized by the plasma-arc method at the buffer gas pressure of 3 Torr. The material has physical properties different from the properties of the material synthesized at pressure of 25 Torr and higher. The low pressure of buffer gas leads to formation of materials consisting of carbon nanoparticles with average size lower than 10nm. The nanoparticles have form of carbon globules, which consist of the graphite-like structure. This structure is the composition of the stacked, twisted and closed nanofragments of graphene. The dominating interlayer distance in the structure is 0.4 nm. The dominating size of crystallinity La is 2.7nm. The graphite-like structure allows to enhance the electrical conductivity in compare with the material synthesized at buffer gas pressure of 25 Torr and higher. Nevertheless the conductivity of the material is significantly lower than the conductivity of pure graphite because of the contact resistance arising from the presence of the outer layer of amorphous carbon on some globules and the presence of the globules of fully amorphous carbon.
作者: Muhammad Aidil Ibrahim, Nur Atikah M. Jani, Oskar Hasdinor Hassan, F. Abdullah, T.I.T. Kudin, Ab Malik Marwan Ali, Muhd Zu Azhan Yahya
摘要: Graphene is a material that has been heavily investigated in many researches due to its beneficial characteristics such as large surface area, low manufacturing cost, high electro conductivity and incredible mechanical strength. Applying the graphene in water-based solvents however can cause agglomeration due to its hydrophobic properties. Researchers have composited the graphene with other materials in overcoming its hydrophobicity. In this research, graphene was nanocomposited with thionine to make it disperse well in water-based solvents while preserving its intrinsic properties. The nanocomposition process involves mixing of both graphene oxide with thionine and were reduced by hydrazine hydrate while reflux heating. The produced mixture was then filtered to obtain the Thionine-Graphene nanocomposite. The obtained sample was then characterized to confirm the composition of both graphene and thionine. Fourier transfer infrared spectroscopy was operated to investigate the chemical bonds and hence concluding the presence of both graphene and thionine in the sample. The preservation of the intrinsic properties of graphene was also investigated through observing the absence of functionalized graphene bonds. Post-investigation reports that the chemical bonds from both of the materials, graphene and thionine were detected confirming the successfulness of the nanocomposition.
作者: Ahmad Fairoz Aziz, Khuzaimah Nazir, S.F. Ayub, N.I. Adam, Muhd Zu Azhan Yahya, Ab Malik Marwan Ali
摘要: 0.5 wt.% of N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD) was introduced into polymer electrolytes based on 30% poly(methyl-methacrylate) grafted natural rubber (MG30) in order to reduce the aging factor of MG30. The polymer electrolyte without 6PPD was used as control. All samples were prepared by using solution cast techniques. The effect of 6PPD in the electrolytes was analysed by using TGA, DSC and FTIR. TGA and DSC results revealed the thermal stability of MG30 electrolytes with 6PPD have higher thermal stability but lower glass transition temperature value. FTIR studies confirmed the existence of LiTF in the sample and prove the occurrence of polymer-salt complexation. Deconvolution techniques analysis on FTIR spectra shows the electrolyte sample with 6PPD display more ion dissociation which reflects to higher ionic conductivity.
作者: Sohail Yasin, Nemeshwaree Behary, Anne Perwuelz, Jin Ping Guan, Guo Qiang Chen
摘要: The organophosphorus compound N-methylol dimethyl phosphonopropionamide (MDPA) is extensively used for durable flame retardant (FR) treatments for cotton fabrics. For optimum finishing treatment, MDPA is used with the Trimethylol melamine (TMM) or dimethylol dihydroxyethylene urea (DMDHEU) for cotton fabric treatments. The amino resins TMM known to pose severe toxic problems such as; breathing problems, headache and most importantly, cancer. In the production, consumption and eventually in the disposal phase of FR with TMM treated cotton fabrics, the release of TMM and toxic emissions cannot be ignored. In this study, mineralization and degradation of the organophosphorus FR compound from the cotton fabric using Advanced Oxidation Process (AOP) was successfully employed. The kinetics of degradation of FR substance from the cotton fabric was studied. The rate of degradation of the FR substance from the cotton fabrics was observed with chemical oxygen demand (COD). The kinetic rate constant equations and characterization of the mineralization and degradation of the FR substance by the AOP reaction was developed with the COD values. The organophosphorus FR on the fabric found to follow the first-order of kinetics of degradation from the cotton fabric.