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Mechanical　Property　and　Microstructure　of　Oxide　Dispersion　strengthened　Nickel-base　superalloy　MA758

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Rare Metals 1997年第1期16卷 46-52页

作者：沙维 the queen's university of belfast 英国

The mechanical property and microstructure of a mechanically alloyed (MA) oxide dispersion strengthened (ODs) nickel base superalloy MA758 were investigated by compression testing and microscopy techniques. It was found that the yield strength of the as extruded fine grain material is significantly dependent on temperature, droping from 880 MPa at 560℃ down to 15 MPa at 1160℃. The yield strain also drops with temperature, from 0.037 at 560℃ to 0.024 at 1160℃. The second part of the current research has revealed large amount of strings of Al 2O 3 particles forming after high temperature annealing in air, aligned along the extrusion direction. Upon annealing in vacuum, such particles do not formed, though Ti/Cr nitrides and carbides are present in small quantities. This phenomenon explains the observed weak transverse mechanical property in several ODs alloys.

关键词： Mechanical properties Metals and alloys Microstructure

Recrystallization　in　Oxide　Dispersion　strengthened　Nickel－base　superalloy　MA760

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Rare Metals 1996年第2期15卷 87-94页

作者：沙维 the queen's university of belfast 英国

The recrystallization behavior of a mechanically alloyetl oxide dispersion strenghened Nibase superalloyMA760 (Ni-19.51 %Cr-6%Al-3. 4 1 %W-1. 19%Fe-1. 02 %Y_2O_3 (wt%)) has been investigated by using acombination of microscopy, ealorimetry and hardness measurement techniques. It has been found that recrystal-lization occurs at very high temperatures and has a very fast kinetics. Recrystallization onset temperature in-creases with increasing heating rate, while recrystallized grain size decreases. The effects of pre-anneal havebeen found to be reducing the stored energy for recrystallization and the subsequent recrystallized grain size. Toexplain all these experimental observations, a model has been proposed considering grain boundary Junction pin-ning during the initial stage of recrystallization process.

关键词： Annealing Metals and alloys Microstructure

Modification of Recrystalization Grain structure of Ytria Dispersion strengthened MA956 Alloy by Pre-deformation

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Rare Metals 1997年第3期16卷 28-34页

作者：沙维 the queen's university of belfast 英国

The effects of cold deformation on recrystallization characteristics of a mechanically alloyed yttria dispersion strengthened alloy (Fe 20%Cr 4.5%Al 0.5%Ti 0.01%C 0.5%Y 2O 3 (wt%)) are studied. Experimental techniques employed include optical and transmission electron microscopy (TEM), differential scanning calorimetry (DsC), and laser processing methods. In addition, a recrystallization grain growth model is presented to explain the observed reduction of recrystallized grain aspect ratio as a result of cold forging.

关键词： Deformation and fracture Metals and alloys Microstructure

Identification of the active sites and mechanism for partial methane oxidation to methanol over copper-exchanged CHA zeolites

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science China Chemistry 2020年第6期63卷 850-859页

作者： Yu Mao P.Hu school of Chemistry and Chemical Engineering The Queen’s University of BelfastBelfastUK

To make methane a suitable energy carrier and transport less costly,it is an urgent and challenging task for us to convert methane to liquid under mild conditions *** this study,we explored partial methane oxidation to methanol by density functional theory(DFT)calculations using a hybrid functional(HsE06)with van der Waals(vdW)*** stabilities of different active sites over ssZ-13 and sAPO-34,two CHA type zeolites,are thoroughly investigated by ab initio molecular dynamics(AIMD)simulations and ab initio thermodynamics *** possible active sites,namely[CuOHCu]2+,[Cu(OH)2Cu]2+,[CuOCu]2+and[CuOH]+,are identified ***-to-methanol reaction mechanisms are further studied upon these most stable active sites,among which[CuOCu]2+and[CuOH]+are proved to be *** migration of species among zeolite pores are also discussed,which accounts for the activity on[CuOH]+*** concept may represent a more complete picture of catalytic reactions over zeolites in general.

关键词： DFT heterogeneous catalysis methane-to-methanol CHA zeolites

Identification of Crystalline Phases in Toothpaste byPowder Diffractometry

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Rare Metals 1996年第2期15卷 128-131页

作者：沙维 the queen's university of belfast 英国

The abrasive crystalline phases in Colgate Regular, Aquafresh , and Macleans tcothpaste were identifiedby X-ray powder diffractometry to be calcium ortho-phaphate hydrate (CaHPO_4 . 2H_2O),calcite (CaCO_3) ,and aragon... 详细信息

关键词： Toothpaste Phase identification X-ray diffraction techniques

Identifying the general trend of activity of non-stoichiometric metal oxide phases for CO oxidation on Pd(111)

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science China Chemistry 2019年第6期62卷 784-789页

作者： Ziyun Wang P.Hu school of Chemistry and Chemical Engineering Queen's University Belfast

Oxidation state changes under reaction conditions are very common in heterogeneous catalysis. However, due to the limitation of experiment and computational methods, the relation between oxidation state and catalytic activity is not clear. Herein, we obtain the most stable structures of palladium oxide films with different oxidation states on palladium metal surfaces using density functional theory calculations and a state-of-the-art optimization method, namely the particle swarm optimization. These structures clearly show the process of palladium oxide film formation on metallic surfaces. Using CO oxidation as a model reaction, we find that the activities increase first and then decrease with the increase of oxidation states, peaking at Pd_4O_3. Our findings offer an understanding of the phase transformation and the activity of non-stoichiometric phases.

关键词： DFT non-stoichiometric oxide CO oxidation

CRYsTALLIsATION KINETICs AND PHAsE TRANsFORMATION BEHAVIOUR OF ELECTROLEss NICKEL-PHOsPHORUs DEPOsIT WITH 6-9wt% PHOsPHORUs CONTENT

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Acta Metallurgica sinica(English Letters) 2001年第6期14卷 419-424页

作者： K.G. Keong, W. sha and s. Malinov (school of Civil Engineering, The queen’s university of belfast, belfast BT7 1NN, UK) school of Civil Engineering The Queen’s University of Belfast

Crystallisation kinetic and phase transformation behaviour of the electroless nickel-phosphorus deposit with 6-9wt% phosphorus content were studied. The deposit was heated in the differential scanning calorimetry (DsC) apparatus to 300℃-800℃ at 20℃/min, followed by the X-ray diffraction (XRD) analysis. The sequence of crystallisation process was: mixture of amorphous and microcrystalline nickel phases → intermediate metastable, f. c. c. nickel and stable N13P phases → f. c. c. nickel and stable Ni3P phases. Preferred orientation of nickel {200} plane was developed after the heating processes. Activation energy of crystallisation process was determined from the DsC analyses at 5-50℃/min. Crystallisation temperatures were found increased with increasing heating rate.

关键词： coating crystallization nickel phase transitions phosphorus X-ray diffraction

Achieving accuracy and efficiency at the same time: a new kinetic Monte Carlo approach for complicated catalytic systems

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science China Chemistry 2018年第12期61卷 1479-1480页

作者： Yu Mao P.Hu school of Chemistry and Chemical Engineering The Queen's University of Belfast

Rational design/screening of more active,more selective,and less expensive catalysts has long been an important target in heterogeneous catalysis [1].In recent decades,the advances of density functional theory (DFT)calculations allow us to theoretically evaluate the activity of *** shown in Figure 1(a),kinetics serves as the link between the atomic-scale properties obtained by DFT and turnover frequency (TOF)of catalysts.

关键词： Achieving accuracy efficiency kinetic Monte Carlo complicated catalytic systems

Photocatalytic OH radical formation and quantification over TiO_2 P25:Producing a robust and optimised screening method

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Chinese Chemical Letters 2018年第6期29卷 773-777页

作者： Caitlin Buck Nathan skillen Jeanette Robertson Peter K.J.Robertson school of Chemistry and Chemical Engineering Queen's University Belfast school of Biological sciences Queen's University Belfast Medical Biology Centre

The development of photocatalytic technology has grown significantly since its initial report and as such,a number of screening methods have been developed to assess activity. In the field of environmental remediation, a crucial factor is the formation of highly oxidising species such as OH radicals. These radicals are often the primary driving force for the removal and breakdown of organic and inorganic contaminants. The quantification of such compounds is challenging due to the nature of the radical,however indirect methods which deploy a chemical probe to essentially capture the radical have been shown to be effective. As discussed in the work presented here, optimisation of such a method is fundamental to the efficiency of the method. A starting concentration range of coumarin from 50 mmol/L to 1000 mmol/L was used along with a catalyst loading of 0.01 g/L to 1 g/L Ti TiO2 to identify that 250 mmol/L and 0.5 g/L Ti TiO2 were the optimum conditions for production. Under these parameters a maximum production rate of 35.91 mmol/L（Rmax= 0.4 mmol/L OH＊ min-1） was achieved which yielded at photonic efficiency of 4.88 OH＊moles photon-1 under UV irradiation. The data set presented also highlighted the limitations which are associated with the method which included; rapid exhaustion of the probe molecule and process inhibition through UV light saturation. Identifying both the optimum conditions and the potential limitations of the process were concluded to be key for the efficient deployment of the photocatalytic screening method.

关键词： Photocatalytic screening OH radical quantification Coumarin Environmental remediation Method optimisation