Abstract: Multilayer structure with SnO2/Ag//SnO2 was prepared on glass substrates by sequential using RF/DC magnetron sputtering at room temperature. In order to estimate and compare with the experimental results in advance, EMP (Essential Macleod Program) simulation program was adopted. EMP simulation results suggested that the multilayered thin film of SnO2 (30 nm)/Ag (10 nm)/SnO2 (30 nm) exhibited the highest visible transmittance of 88.8 % at 550 nm, whereas experimentally measured transmittance showed 85.5 %, somewhat lower than simulation data. Even though most of films exhibit transmittance of about 88 % at 550 nm wavelength, there are some distinct differences between the experimental and simulated results. Sheet resistance (Rs) were almost constant and the lowest Rs value about 9.51 Ω/sq was acquired at the multi layers with the structure of SnO2 (30nm)/Ag (10nm)/SnO2 (30nm). However, the resistivity of the SnO2/Ag/SnO2 multi layer film increased systematically with increasing thickness of SnO2 layer from 30 to 50 nm. SnO2/Ag/SnO2 multilayer with 50 nm of SnO2 thickness resulted in a decrease of ΦTC due to decrease of transmittance. The highest ΦTC value of SnO2/Ag/SnO2 film was obtained at a SnO2 thickness of 35 nm.
Abstract: This study focused on the formation and growth of intermetallic compound (IMC) layer at the interfaces of pad finishes. The thickness of IMC layer, wetting angle, and defects such as floating IMC and voids formation after as reflow and isothermal aging were discussed. In this study, SAC237 (Sn: 99 wt.%, Ag: 0.3 wt.%, Cu: 0.7wt.%) reinforced with 0.01 wt.% of Multi-Walled Carbon Nanotubes (MWCNTs) were soldered on Electroless Nickel Immersion Gold (ENIG) and Immersion Tin (ImSn) pad finishes. Isothermal aging at 150°C for 400h, 800h, and 1200h were conducted after as reflow process. The IMC layer were analysed using optical microscope with image analyzer. The results shows the thickness of IMC layer for both ENIG and ImSn increased as the isothermal aging period increases. The increament was found from 1.49 μm to 1.73 μm for ENIG and 2.51 μm to 5.49 μm for ImSn. Floating IMC and voids formation were also observed on both pad finishes. Wetting angle for ENIG and ImSn varied from 16.21° to 36.85° and 24.27° to 34.41° respectively.
Abstract: In this paper, a series of magnetic Stearic acid (Sa)/Fe3O4/TiO2 nanocomposites were synthesized as a functional phase change materials through a two step methods; sol gel method followed by dispersion technique. Fe3O4/TiO2 nanocomposites were first synthesized by varying the molar ratio of Fe3O4:TiO2 from 1:1 to 1:5 followed by dispersing the synthesized Fe3O4/TiO2 nanocomposites in stearic acid (Sa). The structural properties were confirmed by X-ray diffractometer (XRD), while their chemical compositions were determined from energy dispersive X-ray (EDX). The molecular interaction were detected by Fourier transform infrared spectroscopy (FT-IR). Thermal storage capability such as latent heat and specific heat were detected by differential scanning calorimetry (DSC) while high thermal reliability of their phase change performance were detected by thermogravimetric analysis (TGA) experiment. The result shows that the incorporation of nanocomposites Fe3O4/TiO2 enhance the latent heat as well as heat capacity of phase change materials.
Abstract: Nanoparticles are used to study the rheological characteristics of drilling fluids. Nanoparticles have high surface to volume ratio, therefore only small quantity is required to blend in the drilling fluid. This research evaluates the performance of nanosilica and multi walled carbon nanotubes (MWCNT) as fluid loss additives in water based drilling fluid with various nanoparticles concentration and temperature. The results show that plastic viscosity, yield point and gel strength of drilling fluid increases as the concentration of nanoparticles increased. Drilling fluid with nanosilica gives the highest filtrate loss of 12 ml and mudcake thickness of 10 inch at 1 g concentration at 300°F. However, drilling fluid with MWCNT shows a decreasing trend in fluid loss and mudcake thickness. The results also show that xanthan gum containing 1 g of MWCNT gives 4.9 ml fluid loss and mudcake thickness of 4 inch at 200°F. After aging, plastic viscosity, yield point and gel strength of mud containing nanoparticles decrease significantly especially for 1 g of nanosilica and 0.01 g MWCNT. Fluid loss and mudcake thickness increased when the mud is exposed to temperature above 250°F. The results showed that xanthan gum with MWCNT gives a better rheological performance.
Abstract: Wettability alteration of rock by surfactant has been considered as feasible method for recovery of oil reservoirs by modifying the wettability of rock surface from oil-wet to water-wet condition. The impact of surfactant can be enhanced by adding nanoparticles. Cationic surfactant performed well in carbonate rock by forming ion pairs between cationic head and acidic component of the crude. Meanwhile, nanoparticles will form continuous wedge film between the liquid and solid surface. In this paper, Al2O3 and ZrO2 nanoparticles were used as enhanced oil recovery (EOR) agents. The impact of these two nanoparticles on contact angle and interfacial tension was studied. Besides that, adsorption Cetyltrimethylammonium Bromide (CTAB) surfactant on rock surface was also investigated. The results show a significant change in water-oil contact angle after application of surfactant and nanoparticles. Initial water-oil contact angle for 6 dolomites demonstrate oil-wet condition. Then, the dolomites were submerged in prepared solution for 48 hours. The result shows that, dolomites 2, 5 and 6 changes drastically to more water-wet condition with contact angle 56°, 40° and 47° respectively. For surfactant adsorption, the adsorption is very fast at the beginning. The adsorption rate after 5 minutes was 50 mg/g and after 60 minutes the adsorption rate was 310 mg/g. The adsorption rate slowed down after 60 minutes and after 180 minutes the adsorption rate was 315 mg/g in which the rate of adsorption achieve equilibrium. Nanoparticles retention test and Zeta potential shows that Al2O3 is more stable than ZrO2. The results for interfacial tension (IFT) also show a significant reduction. The IFT value reduces from 8.46 mN/m to 1.65 mN/m and 1.85 mN/m after the application of Al2O3 and ZrO2 nanofluids respectively