Papers by Keyword: Optical Microscope

Abstract: Thin films of Nickel-doped ZnO have been prepared by sol-gel spin coating process. The doping concentration of Ni by weight has been adjusted as 0%, 2% and 5% .In order to examine the effect of doping on the optical properties , ZnO thin films has been characterized by UV-Vis spectroscopy, this shows Nickel doping affects the transmission in regards to the thin films and the band gap. The observed value of gap energy for 2% of Ni by weight is 3.25eV; also, the urbach energy value of “EU” is contrast with the values of energy gap.For ZnO powder nanostructures, we studied the microstructural and morphological properties, it have been characterized by optical microscope and first-principals computing. The ZnO replicas were clearly observed, the band structure and density of states of phase of crystal ZnO computed using Ab Initio methods, confirmed that pure ZnO is a direct band gap semiconductor for B3 phase, whose phase B3 is of ZnS type Blende.

Abstract: This work presents the structural and microstructural properties of zinc oxide (ZnO) powders, for that, we used X-ray diffraction (XRD), Optical microscope as characterization methods. Powder X-ray diffraction data confirm a hexagonal crystal structure formation with space group p63mc of ZnO. By Rietveld refinement, we have determined the microstructural parameters with the c axis of the preferential orientation, the ZnO replicas were clearly observed under an optical microscope. Band structure and density of states of the phase of crystal ZnO computed using Ab Initio methods, confirmed that pure ZnO is a direct band gap semiconductor in hexagonal wurtzite structure.

Abstract: There has been a significant increase in the use of composite materials to reinforce metallic structures. Such an increase has been especially noted in marine and underground applications, where there is a higher corrosion impact. Whilst there have been several attempts to investigate the mechanical properties of several synthesized composite materials, few of these have analyzed the corrosion of such composite materials at different weight ratios. The aim of this paper is to explore the best weight ratios of a graphite/Zinc composite matrix that would yield the lowest corrosion rate for a variety of applications. The research is validated using experimentation based on six additives of graphite (1wt%, 2.5wt%, 4wt%, 6wt%, 8wt%, and 10wt%), which are used as reinforcements for a range of weight ratios. The additives were prepared using the powder metallurgy method. The corrosion rate for all specimens used was carried out at the room temperature of 27 °C. Analysis results showed that 1wt% of graphite additive has the highest corrosion resistance compared to other weight ratios tested. This has been verified by examining the microstructure of the composite using an optical microscope for 12h, 24h, and 48h of immersion time in a 1M HCl acid solution.

Abstract: CIPP renovation methods are often used for renovation of sewers and water mains. They can also be used for renovation of gas and product pipelines. However, the presence of chemicals in these pipelines cannot be excluded. For this reason, the ability of CIPP liners to resist chemicals should be examined. This paper deals with problematics of influence of chemicals (acids and bases) on CIPP liners. Visual changes can be observed using an optical microscope. Structural changes are evident from the results of short-term bending tests.

Abstract: The developing of Composites Metallic Matrix for Aluminum (AMMCs) is one of the leading engineering applications requirements because of the excellent mechanical characteristics low weight with high strength for this metal. This research investigated the impact of ZnO particles on the Compressive strength, Hardness, and Wear characteristics of Al metallic matrix composite manufactured by method stir casting. The strengthening added different weight percent (0, 2, 4, 6, 8 and 10) % ZnO. The microstructure of specimens is the analysis by an optical microscope and determines the compressive strength, hardness, and wear characteristics which increase with an increased weight percentage of ZnO. The increase in the percent of Brinell hardness is (15%), (25%), (35%), (40%), and (50%) for aluminium reinforced with 2, 4, 6, 8, 10 wt. % ZnO particles specimens respectively. Finally, it could be found that the volume loss was drastically reduced by raising the amount of zinc oxide, thus exceeding the composite minimum amount, which represents the total percentage of zinc oxide (10 percent).

Abstract: Photonic jet microscopy is a technical field of microscopy applying photonic jet phenomenon to increase the resolution of objects or area of objects being observed. Mostly it is used in optical microscopy as the demand of visual observations are increased, especially for the micro-metric biological objects. In addition to our previous works inoptical assessment of observing a micrometric object under a microsphere using an optical microscope, now we made the electromagnetic assessment. It concludes if smaller microsphere magnifies greater than bigger microsphere. Therefore, applying photonic jet microscopy for visual observation is getting closer.

Abstract: In present scenario, nanocomposites are playing an imperative role in most of the industrial application due to their outstanding performances with good mechanical properties. The aim of this research is to study the effect of tool rotational speed and traverse speed on micro structural and hardness properties of fabricated surface nanocomposites of Al-Al₂O₃. By varying tool rotational and traverse speed at a constant volume percentage the surface nanocomposites were produced by applying one pass of friction stir processing. A clear view of material flow and defect characterization in the stir zone were studied. Optimum condition of tool rotational speed of 1120 rpm and tool traverse speed of 16 mm/min was obtained to produce a defect free surface nanocomposite. Microstructure observations were carried out through optical microscope and micro hardness test were conducted by using Vickers micro hardness tester. From the phase volume fraction analysis, it was observed that the Al₂O₃ nanoparticles were well dispersed in the stir zone. It was found that, the tool speed and traverse speed had a significant impact on microstructure properties as well as mechanical properties of the fabricated surface nanocomposite. From the final results it was found that a mixture of dynamically restored ultra fine grins with a mean size of ~80 nm and the average micro hardness value of 130HV were achieved through a fabricated aluminium Al₂O₃ nanocomposite.

Abstract: Cu-Al-Be Ternary alloys are prepared by ingot metallurgy route, which exhibits parent phase or Austenite phase at high temperature and Martensite phase at low temperature and also exhibits shape memory effect upon quenching to lower temperature. The Cu-Al-Be SMA was in the range of 10-12wt% of Al and 0.4-0.5 wt% of Be is chosen for present study and different amount of quaternary element is added to the ternary alloy. The variation in shape memory effect, transformation temperature and microstructure is studied by using bend test, differential scanning calorimeter and Optical microscope.

Abstract: Copper based shape memory alloys are the alloys prepared with the combination of 66-88 wt% of copper, 10-14 wt% of aluminum, 0.3-0.6 wt% of beryllium and 0.1-0.4 wt% of manganese in the induction furnace through ingot metallurgy. The prepared SMAs is subjected to homogenization, it was observed that the samples exhibits Beta phase at high temperature and shape memory effect after going through step quenching to a low temperature. Microstructure and Shape memory effect was studied with the help of optical microscope and bend test respectively. It was seen that with increase in wt % of manganese the shape memory effect also increases.

Abstract: In the present study, the corrosion behaviour of the Al2219, Boron carbide and Graphite has been investigated. The Aluminium Metal Matrix Hybrid Composites were fabricated by two step stir casting technique. Corrosion tests were carried out with the natural sea water (3.5 wt % NaCl) according to standard procedure. The tests were conducted at room temperature by cyclic polarization technique for a definite time interval. After the test, material loss was calculated by weight loss method. The surface morphology of the specimen before and after corrosion was studied using the optical microscope images. The test result reviles that, the corrosion rate of the composite was greater than the base alloy, but the corrosion of the hybrid composite is the most compared to the alloy and monolithic composite.