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Ahmad M.,Bahauddin Zakariya University | Ahmad M.,Zhejiang University | Ahmed E.,Bahauddin Zakariya University | Hong Z.L.,Zhejiang University | And 4 more authors.
Applied Surface Science | Year: 2013

Copper doped ZnO nanoparticles embedded on multi-walled carbon nanotubes (CNTs) were successfully synthesized using a facile, nontoxic sol method. The resulting visible light-responsive Cu-doped ZnO/CNTs composites were characterized using powder X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM), transmission electron microscope (TEM), scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS) and Brunauer Emmett Teller (BET) surface area analyzer. Optical properties of Cu-doped ZnO/CNTs nanocomposites, studied using UV-vis diffuse reflectance spectroscopy and photoluminescence spectroscopy (PL), which exhibited extended light absorption in visible light region and possessed better charge separation capability, respectively as compared to Cu-doped ZnO, pure ZnO and ZnO/CNTs composite. The photocatalytic activity was tested by degradation of methyl orange (MO) dye under visible light irradiation. The results demonstrated that Cu-doped ZnO/CNTs nanocomposites effectively bleached out MO, showing an impressive photocatalytic enhancement over ZnO, commercial ZnO, Cu-doped ZnO nanoparticles and ZnO/CNTs nanocomposites. Chemical oxygen demand (COD) of textile wastewater was also measured before and after the photocatalysis experiment under sunlight to evaluate the mineralization of wastewater. The significant decrease in COD of the treated effluent revealed a complete destruction of the organic molecules along with color removal. This dramatically enhanced photoactivity of nanocomposite photocatalysts was attributed to greater adsorptivity of dyes, extended light absorption and increased charge separation efficiency due to excellent electrical properties of carbon nanotubes and the large surface area. © 2013 Elsevier B.V. All rights reserved.

Afzal M.,University of Engineering and Technology Lahore | Ajmal M.,University of Engineering and Technology Lahore | Nusair Khan A.,Institute of Industrial Control System | Hussain A.,Pakistan Institute of Lasers and Optics | Akhter R.,Pakistan Institute of Lasers and Optics
Optics and Laser Technology | Year: 2014

Tungsten carbide cermet powder with 12%Co was deposited on stainless steel substrate by air plasma spraying method. Two types of coatings were produced i.e. thick (430 μm) and thin (260 μm) with varying porosity and splat morphology. The coated samples were treated with CO2 laser under the shroud of inert atmosphere. A series of experimentation was done in this regard, to optimize the laser parameters. The plasma sprayed coated surfaces were then laser treated on the same parameters. After laser melting the treated surfaces were characterized and compared with as-sprayed surfaces. It was observed that the thickness of the sprayed coatings affected the melt depth and the achieved microstructures. It was noted that phases like Co3W3C, Co3W9C4 and W were formed during the laser melting in both samples. The increase in hardness was attributed to the formation of these phases. © 2013 Elsevier Ltd.

Mansoor M.,Institute of Industrial Control System | Kinloch I.,University of Manchester | Derby B.,University of Manchester
Key Engineering Materials | Year: 2010

The production of substrates coated with carbon nanotubes (CNTs) in well-defined patterns is desirable for sensor applications. In the present work, nickel based catalytic inks were prepared and printed on silicon substrates using inkjet delivery. Subsequently, the substrates were subjected to calcination and chemical vapour deposition for the growth of aligned CNTs. Scanning electron microscopy, transmission electron microscopy and Raman spectroscopy were used to characterize the CNTs. Various concentrations and formulations of ink preparations were studied to investigate the effect of these parameters on the growth and structure of the CNTs.

Ahmad Z.,Zejiang University | Akbar S.,Institute of Industrial Control System | Farooque M.,Institute of Industrial Control System | Ul Haq A.,Mohammad Ali Jinnah University | Yan M.,Zejiang University
Philosophical Magazine Letters | Year: 2011

Magnetic and microstructural properties of Nb-doped Al-Ni-Co-Cu-Ti-Fe permanent magnets were studied in terms of various processing conditions and niobium concentration. Optimization in magnetic properties can be obtained by controlling microstructures and adopting proper processing thermal cycle temperature, holding time, cooling rate, and magnetic field strength. Niobium addition up to 1.0 wt% leads to the refinement of the microstructure, promotes shape anisotropy, and improves magnetic properties. The best magnetic properties in 8.33Al-15.33Ni-34.67Co-3.9Cu-5.4Ti-1.0Nb-Fe magnets are obtained as coercive force (Hc) of 1.53 kOe (121.80 kA/m), remanence (Br) of 7.98 kG (0.79 T), saturation magnetization (Bs) of 19.0 G (1.90 T), and magnetic energy ((BH)max) of 4.35 MGOe (34.62 kJm3). These magnets are attractive for future applications due to their good magnetic properties, better machineability, and economical processing. © 2011 Taylor & Francis.

Nusair Khan A.,Institute of Industrial Control System
Key Engineering Materials | Year: 2010

Titanium aluminides intermetallic compounds have received great attention during the past decade, since they have the potential, in aircraft and automotive engines, to replace the high density Ni-base superalloys However, these intermetallics possess poor oxidation properties at high temperatures. Previous studies showed that protective alumina scale formation on ?-TiAl can be obtained by small additions (around 2 at.%) of Ag. In the present study, a number of cast Ti-Al-Si alloys were investigated in relation to transient oxide formation in air at 1300oC. After various oxidation times the oxide composition, microstructure and morphology were studied by combining a number of analysis techniques. The TiAl-Si alloys appear to form Al Ti and Si oxides. However, the formation of silicon oxide at the interface of base metal and scale slows down the oxidation rate significantly.

Quddos A.,Institute of Industrial Control System | Hussain S.M.,Institute of Industrial Control System | Hafiz-Ur-Rehman,Institute of Industrial Control System | Abbas T.,Institute of Industrial Control System
Key Engineering Materials | Year: 2010

Polymer composites are used in numerous applications. In spite of this fact, new developments are still under way to explore in other field of application of these materials and to tailor their properties for more extreme condition. A particular emphasis is focused on fillers content is summarized. Some steps towards the functionally graded materials are illustrated. The FT-IR spectroscopic studies revealed the information about curing of epoxy with fillers. It was observed that mechanical properties like tensile strength, hardness etc get enhanced up with filler contents. The effect of the different formulations were investigated and discussed for optimum process condition.

Afzal M.,University of Engineering and Technology Lahore | Ajmal M.,University of Engineering and Technology Lahore | Nusair Khan A.,Institute of Industrial Control System
Tribology Transactions | Year: 2013

Tungsten carbide (WC-Co) coatings are extensively utilized in tribological environments. WC-12%Co coatings had been produced by utilizing an air plasma spraying system. The coatings were produced at different spraying distances, which affected the microstructure and the formation of different metallurgical phases of the coating. The six coating systems produced at 80- to 130-mm standoff distances were then characterized using scanning electron microscopy, X-ray diffraction (XRD), and a tribometer for wear rate and coefficient of friction (COF). The properties of the coatings were correlated with the microstructure, formation of different phases, and residual stresses of the coating. It was observed that the spraying distance from 100 to 110 mm resulted in optimum wear properties. © Society of Tribologists and Lubrication Engineers.

Ahmad Z.,Zhejiang University | Ahmad Z.,Institute of Industrial Control System | Ma T.,Zhejiang University | Tao S.,Zhejiang University | Yan M.,Zhejiang University
Journal of Magnetism and Magnetic Materials | Year: 2012

The Fe 63B 23Nd 7Y 3Nb 3Cr 1 nanocomposite magnets in the form of sheets have been prepared by copper mold casting technique. The phase evolution, crystal structure, microstructural and magnetic properties have been investigated in the as-cast and annealed states. The as-cast sheets show magnetically soft behaviors which become magnetically hard by thermal annealing. The optimal annealed microstructure was composed of nanosize soft magnetic α-Fe (1929 nm) and hard magnetic Nd 2Fe 14B (4555 nm) grains. The best hard magnetic properties such as intrinsic coercivity, jH c of 1119 kA/m, remanence, B r of 0.44 T, magnetic induction to saturation magnetization ratio, M r/M s=0.61 and maximum energy product, (BH) max of 55 kJ/m 3 was obtained after annealing at 680 °C for 15 min. The annealing treatment above 680 °C results in non-ideal phase grains growth, which degrade the magnetic properties. © 2011 Elsevier B.V. All rights reserved.

Rehman S.U.,National University of Sciences and Technology | Khan M.,National University of Sciences and Technology | Nusair Khan A.,Institute of Industrial Control System | Imran Khan M.,Ghulam Ishaq Khan Institute of Engineering Sciences and Technology | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

Microstructural analysis, evolution of phase transformation temperatures and shape memory properties for Ti50Ni15Pd 25Cu10 high temperature shape memory alloys were investigated in solution treated and aged conditions. It is shown that aging at 600 °C for 3 h resulted in the formation of two types of fine precipitates i.e. TiPdCu and Ti2Pd. It is observed that due to the formation of these precipitates, martensite start temperature under stress free and constrained (500 MPa) conditions are decreased by 32 °C and 29 °C respectively. Recovery ratio of 76% obtained for solution treated sample increased to 94% at 500 MPa for the 600 °C aged sample; resultantly the irrecoverable strain is decreased by 18%. Training for 5 thermal cycles was carried out under stress free condition resulted in the decrease of thermal hysteresis by 5 °C for the solution treated sample, whereas thermal hysteresis of the aged sample remained stable. Similarly thermomechanical training cycles at 500 MPa demonstrated an improvement in the recovery ratio by 14% and 5% for solution treated and 600 °C aged samples respectively. Aging at 600 °C for 3 h and thermomechanical training greatly improved the cyclic stability and shape memory properties of Ti50Ni15Pd 25Cu10 high temperature shape memory alloys. © 2014 Elsevier B.V. All rights reserved.

Mansoor M.,Institute of Industrial Control System | Lu J.,University of Technology of Troyes
Key Engineering Materials | Year: 2010

In the domain of incremental nanotechnology, surface mechanical attrition treatment is a technique which can transform superficial structure of a material to nanocrystalline without changing the chemical composition. This study is a part of the development and implementation of the technique by using ultrasonic vibrations. The material used is pure titanium in rolled and annealed condition. The nanocrystalline structure is characterized using X-ray diffraction (XRD), and transmission electron microscopy (TEM). The measured grain size is in the order of 5∼60 nm. A correlation in the results of XRD and TEM is also discussed.

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