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Sand production is a critical issue in petroleum wells. The critical total drawdown (CTD) is an essential indicator of the onset of sand production. Although some models are available for CTD prediction, most of them are proven to lack accuracy or use commercial software. Furthermore, the previous correlations have not studied the trend analysis to verify the correct relationships between the parameters. Therefore, this study aims to build accurate and robust models for predicting CTD using response surface methodology (RSM) and support vector machine (SVM). The RSM is utilized to obtain the equation without using any software. The SVM model is an alternative method to predict the CTD with higher accuracy. This study used 23 datasets to develop the proposed models. The CTD is a strong function of the total vertical depth, cohesive strength, effective overburden vertical stress, and transit time with correlation coefficients (R) of 0.968, 0.963, 0.918, and −0.813. Different statistical methods, that is, analysis of variance (ANOVA), F-statistics test, fit statistics, and diagnostics plots, have shown that the RSM correlation has high accuracy and is more robust than correlations reported in the literature. Moreover, trend analysis has proven that the proposed models ideally follow the correct trend. The RSM correlation decreased the average absolute percent relative error (AAPRE) by 12.7% compared to all published correlations' AAPRE of 22.6%–30.4%. The SVM model has shown the lowest AAPRE of 6.1%, with the highest R of 0.995. The effects of all independent variables on the CTD are displayed in three-dimensional plots and showed significant interactions. The authors would like to thank the Yayasan Universiti Teknologi PETRONAS (YUTP FRG Grant No: 015LC0-428) at Universiti Teknologi PETRONAS financial support. Open access funding is provided by the Qatar National Library. Scopus

Hydraulic fracturing is a widely employed well stimulation technique in which a synthesized fracking fluid is pumped into the well bore at high pressures to propagate fractures in rock formation matrix for hydrocarbon production. Proppant being one of the essential component of fracturing fluid is used to keep the hydraulically induced fractures open and conductive by acting as a mechanically strong support particle. Hydraulic fracturing operations are gradually shifting into deeper and low permeability (tight) formation at elevated temperature and pressure conditions at which conventionally used silica sand is becoming unviable as proppant due to its crushing. For resin-coated sand (RCS), temperatures greater than 60°C under high pressures, the glass transition temperature (Tg) threshold limit of polyurethane-based resin coating is reached at which this applied coating tends to soften that results reduction in the mechanical strength of the coated sand pack. Glass beads are also considered as good contestant for proppant that were selected in this study due to their high roundness and sphericity. They were drip coated with urethane resin incorporated with three different concentrations of 0.1 wt%, 0.5 wt% and 1 wt% carbon nanotubes (CNTs) and reduced graphene oxide (rGO) nanofillers, respectively. Crush test analysis by means of Universal Testing Machine (UTM) revealed significant improvement in the mechanical strength of coated glass bead proppants. 0.5 wt% loading of CNTs into urethane resin proved to be the best optimum concentration at which the mechanical strength of the coated glass bead improved by 84% along with 40% reduction in fines generation due to its containment within the applied coating. Crush test results also further revealed that nanofillers concentration loadings greater than the optimum threshold limit into urethane resin promoted their mutual agglomeration that resulted in profound reduction in mechanical strength of coated glass beads therefore resulting in more crushing and higher generation of undesired and detrimental fine particles.

Dye-Sensitized Solar Cells have emerged as solar technology for practical application as building-integrated photovoltaic (BIPV) due to low-cost processing, working ability in the ambient environment, and colour transparency. The colour transparency is inherited from the nanostructured mesoporous TiO2 and colourful dye. However, mesoporous TiO2 possesses poor electron transport properties due to multiple grain boundaries, resulting in undesirable recombination reactions that lead to the loss of photoconversion efficiency (PCE). Reduced graphene oxide (rGO) is incorporated in the TiO2 matrix to improve its electron transport properties. Nevertheless, rGO cannot give full benefit of graphene due to its defective structure, which promotes recombination. Therefore, here a solvent exfoliated high-quality graphene in mesoporous TiO2 photoelectrode having mixed phase composition anatase, rutile, and brookite phase is introduced. Graphene/TiO2 hybrid structures are produced with different graphene loading, and their structural, optical, and electron transport properties are thoroughly investigated. Electrochemical impedance spectroscopy (EIS) indicates that electron lifetime increases by 159%, electron diffusion length increases by 25%, while recombination rate reduces by 62.77% than the pure TiO2 at optimum graphene loading (0.0025 wt%). Consequently, an increase of 18.45% and 30.89% PCE is obtained relative to pure TiO2 and commercial paste, respectively.

Covalent Functionalized-Multi wall carbon nanotubes (CF-MWCNTs) and Covalent Functionalized-graphene nanoplatelets (CF-GNPs) with hexagonal boron nitride (h-BN) were suspended in distilled water to prepare the hybrid nanofluids as working fluids inside the Flat Plate Solar Collector (FPSC). Different concentrations of the hybrid nanoparticles were considered and Tween-80 (Tw-80) was used as a surfactant. The stability and thermophysical properties were tested using different measurement tools. The structural and morphological properties were examined using FTIR, XRD, UV–vis spectrometry, HRTEM, FESEM, and EDX. The thermal efficiency of FPSC were tested under different volumetric flow rates (2 L/min, 3 L/min, and 4 L/min), whereas the efficiency of the collector was determined based on ASHRAE standard 93-2010. As a result, the most thermal-efficient solar collector improved up to 85% with hybrid nanofluid as the absorption medium at 4 L/min flow rate. Increment in nanoparticles’ concentrations enhanced thermal energy gain and resulted in higher fluid outlet temperature.

Bubble point pressure (Pb) is essential for determining petroleum production, simulation, and reservoir characterization calculations. The Pbcan be measured from the pressure-volume-temperature (PVT) experiments. Nonetheless, the PVT measurements have limitations, such as being costly and time-consuming. Therefore, some studies used alternative methods, namely, empirical correlations and machine learning techniques, to obtain the Pb. However, the previously published methods have restrictions like accuracy, and some use specific data to build their models. In addition, most of the previously published models have not shown the proper relationships between the features and targets to indicate the correct physical behavior. Therefore, this study develops an accurate and robust correlation to obtain the Pbapplying the Group Method of Data Handling (GMDH). The GMDH combines neural networks and statistical methods that generate relationships among the feature and target parameters. A total of 760 global datasets were used to develop the GMDH model. The GMDH model is verified using trend analysis and indicates that the GMDH model follows all input parameters' exact physical behavior. In addition, different statistical analyses were conducted to investigate the GMDH and the published models' robustness. The GMDH model follows the correct trend for four input parameters (gas solubility, gas specific gravity, oil specific gravity, and reservoir temperature). The GMDH correlation has the lowest average percent relative error, root mean square error, and standard deviation of 8.51%, 12.70, and 0.09, respectively, and the highest correlation coefficient of 0.9883 compared to published models. The different statistical analyses indicated that the GMDH is the first rank model to accurately and robustly predict the Pb 2022 American Chemical Society. All rights reserved. The authors would like to give their sincerest thanks to the Universiti Teknologi PETRONAS for supporting this study under YUTP-Grant cost center 015LC0-105. Scopus

The oil formation volume factor is one of the main reservoir fluid properties that plays a crucial role in designing successful field development planning and oil and gas production optimization. The oil formation volume factor can be acquired from pressure-volume-temperature (PVT) laboratory experiments; nonetheless, these experiments' results are time-consuming and costly. Therefore, many studies used alternative methods, namely empirical correlations (using regression techniques) and machine learning to determine the formation volume factor. Unfortunately, the previous correlations and machine learning methods have some limitations, such as the lack of accuracy. Furthermore, most earlier models have not studied the relationships between the inputs and outputs to show the proper physical behaviors. Consequently, this study comes to develop a model to predict the oil formation volume factor at the bubble point (Bo) using an adaptive neuro-fuzzy inference system (ANFIS). The ANFIS model was built based on 924 data sets collected from published sources. The ANFIS model and previous 28 models were validated and compared using the trend analysis and statistical error analysis, namely average absolute percent relative error (AAPRE) and correlation coefficient (R). The trend analysis study has shown that the ANFIS model and some previous models follow the correct trend analysis. The ANFIS model is the first rank model and has the lowest AAPRE of 0.71 and the highest (R) of 0.9973. The ANFIS model also has the lowest average percent relative error (APRE), root mean square error (RMSE), and standard deviation (SD) of -0.09, 1.01, 0.0075, respectively. The authors express their appreciation to the Universiti Teknologi PETRONAS for supporting this work under the YUTP-Grant cost center 015LC0-098. They also especially thank COREOR, Petroleum Engineering, Universiti Teknologi PETRONAS, for supporting this work. Scopus

Polyaniline (PANI) is an attractive alternative to platinum counter electrode for dye-sensitized solar cell (DSSC) due to its exceptionally low-cost. However, deposition of PANI film over FTO (Fluorine doped tin oxide) glass surface is very difficult. Here, we demonstrate a novel approach to grow PANI via in-situ polymerization on a porous few-layer graphene (FLG) support which has been prepared by simple solvent exfoliation method and deposited on FTO glass by tape casting. The existence of PANI on few-layer graphene is verified by scanning electron microscopy (SEM) images/energy-dispersive X-ray spectroscopy (EDX) mapping, Raman spectrum, X-ray photoelectron spectroscopy (XPS). While, the presence of PANI in the form of emeraldine salt is confirmed by Fourier transformation infrared spectroscopy (FTIR) and UV-Vis absorbance spectroscopy. DSSC based on Gr/PANI and Pt counter electrode (CE) exhibited photoconversion efficiency (PCE) of 3.58% and 3.97% respectively, under one sun at 1 cm2 active area. Electrochemical impedance spectroscopy (EIS) reveals that Gr/PANI based symmetrical cells exhibited higher double layer capacitance than Pt based symmetrical cells, believed to be attributed to higher catalytic active sites. However, Gr/PANI and Gr CEs displayed higher charge transfer resistance and Warburg impedance compared to Pt CE, resulting in superior PCE performance for Pt DSSC. Although the PCE of DSSC with Gr/PANI CE could not exceed the DSSC with Pt CE, but its optical properties and photovoltaic performance are comparatively good for consideration as the alternative.

Sand management is essential for enhancing the production in oil and gas reservoirs. The critical total drawdown (CTD) is used as a reliable indicator of the onset of sand production; hence, its accurate prediction is very important. There are many published CTD prediction correlations in literature. However, the accuracy of most of these models is questionable. Therefore, further improvement in CTD prediction is needed for more effective and successful sand control. This article presents a robust and accurate fuzzy logic (FL) model for predicting the CTD. Literature on 23 wells of the North Adriatic Sea was used to develop the model. The used data were split into 70% training sets and 30% testing sets. Trend analysis was conducted to verify that the developed model follows the correct physical behavior trends of the input parameters. Some statistical analyses were performed to check the model’s reliability and accuracy as compared to the published correlations. The results demonstrated that the proposed FL model substantially outperforms the current published correlations and shows higher prediction accuracy. These results were verified using the highest correlation coefficient, the lowest average absolute percent relative error (AAPRE), the lowest maximum error (max. AAPRE), the lowest standard deviation (SD), and the lowest root mean square error (RMSE). Results showed that the lowest AAPRE is 8.6%, whereas the highest correlation coefficient is 0.9947. These values of AAPRE (20% AAPRE). Moreover, further analysis indicated the robustness of the FL model, because it follows the trends of all physical parameters affecting the CTD.

The data in this article present the effective parameters of experimental ultrasonication process on the dispersion stability of graphene nanoplatelets (GNPs) grafted with a natural polymer of Gum Arabic (GA). These datasets are supporting the article “Natural Polymer Non-Covalently Grafted Graphene Nanoplatelets for Improved Oil Recovery Process: A Micromodel Evaluation” [1]. The datasets were gained during experiments conducted at various dwell time (30, 60, 90 and 120 min) at constant power amplitude (60%) of sonication for preparing the stable GA-GNP/brine solutions aiming cost-effective and green agent solution for chemical enhanced oil recovery (C-EOR). The GA-GNPs dispersion data was verified using particle size analyser and UV–Vis measurements. The optimized time and power amplitude parameters of the sonication process were utilized for preparing stabilized samples of GA grafted GNPs in regarding to research work on Natural Polymer Non-Covalently Grafted Graphene Nanoplatelets for EOR. The dispersion stability of GA-GNPs nanofluids at reservoir conditions of high salinity and high temperatures (HSHT) was further demonstrated in the measured data through the sedimentation of nanoparticles. © 2020 Universiti Teknologi Petronas, UTP Ural Federal University, UrFU: 015ME0-064 Authors are expressing their thankful remarks to Universiti Teknologi PETRONAS (UTP) - Malaysia and Ural Federal University (UrFU) – Russia for supporting the research under International matching research grant, UTP; CS: 015ME0-064 and Act 211 Government of the Russian Federation; contract № 02.A03.21.0006. The first author, in particular, is grateful to UTP for supporting his PhD study under Graduate Assistance (GA) scheme.

Covalent functionalization (CF-GNPs) and non-covalent functionalization (NCF-GNPs) approaches were applied to prepare graphene nanoplatelets (GNPs). The impact of using four surfactants (SDS, CTAB, Tween-80, and Triton X-100) was studied with four test times (15, 30, 60, and 90 min) and four weight concentrations. The stable thermal conductivity and viscosity were measured as a function of temperature. Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) and Raman spectroscopy verified the fundamental efficient and stable CF. Several techniques, such as dispersion of particle size, FESEM, FETEM, EDX, zeta potential, and UV-vis spectrophotometry, were employed to characterize both the dispersion stability and morphology of functionalized materials. At ultrasonic test time, the highest stability of nanofluids was achieved at 60 min. As a result, the thermal conductivity displayed by CF-GNPs was higher than NCF-GNPs and distilled water. In conclusion, the improvement in thermal conductivity and stability displayed by CF-GNPs was higher than those of NCF-GNPs, while the lowest viscosity was 8% higher than distilled water, and the best thermal conductivity improvement was recorded at 29.2%.

The FTO/TiO2 interface plays a crucial role in the performance of dye-sensitized solar cells (DSSCs). The uneven microstructure morphology of FTO (fluorine-doped tin oxide) glass surface and high porosity of TiO2 layer produce tiny gaps and voids at the FTO/TiO2 interface that breaks the connectivity, leading to an increase in the recombination process. In the current work, a dual functional passivating layer is introduced by the combination of the graphene/TiO2 compact layer. The excellent mobility and flexibility of graphene is capitalized using its layer to fill the voids in the FTO surface, which can consequently reduce the charge transfer resistance at the interface, while the added TiO2 compact layer avoids direct contact with the electrolyte thus reducing the recombination. Graphene was synthesized by the facile solvent exfoliation method with the assistance of the probe sonication process. The parameters of sonication were optimized to achieve high-quality concentrated graphene inks (0.177–0.51 mg/ml). Raman spectroscopy and transmission electron microscopy (TEM) revealed that the graphene obtained is of a few-layer type. Electrochemical impedance spectroscopy (EIS) analysis indicated that the incorporated compact layer of graphene/TiO2 was capable of accelerating the charge transfer and reducing the recombination process at the FTO/TiO2 interface. Consequently, the photoconversion efficiency (PCE) for the device (1 cm2 active area) with double-coated graphene layer under one sun irradiation (AM 1.5) was found to be 49.49% higher than the conventional one.

Thermal management of electronics is a great challenge to achieve optimum performance. Nano materials provide a pathway to increase thermal conductivity but nano particles uniform dispersion in the matrix is very difficult. This study focuses on dispersion of functionalized multi-walled carbon nano tubes in copper to improve thermal conductivity of copper. Copper/Carbon Nano Tubes (CNTs) composites were developed via powder injection moulding. Feedstock was compounded using Z-blade mixer and defect free green parts were produced by injection moulding. Binder was removed by solvent and thermal means followed by sintering in argon at 1050 ℃. Thermal conductivity and reliability tests were performed on sintered nano composite specimen at various temperatures. Results showed good dispersion of CNTs in copper and thermal conductivity measured was 550–580 w/m.k. A decrease of 27–37% in thermal conductivity was recorded during thermal cycling of sintered composite and the reduced thermal conductivity value is still 80% higher than pure copper.

Apparent and plastic viscosities are two of the significant rheological properties of drilling fluid. Monitoring the apparent and plastic viscosities during drilling operations is essential to prevent various drilling problems and achieve successful drilling operations. Due to the constraints associated with experimental measurements, a reliable prediction is regarded as an excellent alternative for quick assessment of the apparent and plastic viscosities. There were many attempts taken to develop models to predict the apparent and plastic viscosities. However, the published models' main problems are their lack of accuracy and limitation of the parameters included. Therefore, this work presents new statistical-based empirical correlations for the prediction of apparent and plastic viscosities. The developed correlations relate the apparent viscosity and plastic viscosity to some variables, viz. bentonite, nanoclay concentration, nanosilica concentration, and temperature. Published data were utilized, and Response Surface Methodology (RSM) was used to obtain the mathematical relation between the variables and responses and describe the variables' interactions. ANOVA then validated the correlations, F-statistics test, fit statistics, and Pareto chart standardised effects. The validation has shown that the RSM models were more robust with high accuracy. The influence of the independent variables on the apparent and plastic viscosities of the drilling fluids was established in response surface plots (3D), and the interaction between variables in the system was found statistically significant. The results show that the RSM model's performance is accurate, reliable, and can, hence, be used for precise prediction of apparent and plastic viscosities.

Low stability of the colloidal suspension and the agglomeration phenomena of nanoparticles are the main challenges that restrict nanofluid applications in enhanced oil recovery at reservoir conditions. In this study, graphene nanoplatelets (GNPs) grafted with Gum Arabic (GA) were successfully prepared and evaluated as a cost-effective agent for chemically enhanced oil recovery. The physical and morphological properties of the GA-grafted GNPs (GA-GNPs) were characterized using Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, thermal gravimetric analysis, and transmission electron microscope. GA-GNP powder was prepared and dispersed in high-salinity brine of 30,000 ppm as the base fluid with concentrations of 0.01, 0.05, and 0.1 mg/ml. Investigation results showed that the developed nanofluids exhibited good stability at high salinity and temperature. A reduction in the value of oil–brine interfacial tension (IFT) by 61.0% in the presence of GA-GNPs was observed. The contact angle was remarkably changed from 108° to 20° (81.0% reduction) after dispersing 0.05 mg/mL of GA-GNPs in the brine, which indicates that the wettability of glass slices was altered from oil- to water-wet. After flooding GA-GNP-based brine in the glass micromodel, an augmentation in the oil recovery of approximately 15% and 19% was observed for 0.01 and 0.05 mg/ml of GA-GNPs, respectively. Hence, the wettability alteration plays a more important and effective role than IFT in improving oil recovery with even ultralow concentrations of GA-GNPs. The viscosity of the brine was remarkably improved by 63% after adding 0.05 mg/ml of the prepared GA-GNP powder, which in turn reduced the fingering phenomena during flooding noticeably. These findings indicate that the GA-GNP-based nanofluids can significantly improve the mobility of the residual oil from the porous media to the production well with high efficiency of oil displacement at reservoir conditions.

The chemical sand consolidation methods involve pumping of chemical materials, like furan resin and silicate non-polymer materials into unconsolidated sandstone formations, in order to minimize sand production with the fluids produced from the hydrocarbon reservoirs. The injected chemical material, predominantly polymer, bonds sand grains together, lead to higher compressive strength of the rock. Hence, less amounts of sand particles are entrained in the produced fluids. However, the effect of this bonding may impose a negative impact on the formation productivity due to the reduction in rock permeability. Therefore, it is always essential to select a chemical material that can provide the highest possible compressive strength with minimum permeability reduction. This review article discusses the chemical materials used for sand consolidation and presents an in-depth evaluation between these materials to serve as a screening tool that can assist in the selection of chemical sand consolidation material, which in turn, helps optimize the sand control performance. The review paper also highlights the progressive improvement in chemical sand consolidation methods, from using different types of polymers to nanoparticles utilization, as well as track the impact of the improvement in sand consolidation efficiency and production performance. Based on this review, the nanoparticle-related martials are highly recommended to be applied as sand consolidation agents, due to their ability to generate acceptable rock strength with insignificant reduction in rock permeability.

Hydraulic fracturing is one of the stimulation techniques that has been used to increase the hydrocarbon flow in unconventional reservoirs. Proppants are normally used to maintain the fracture conductivity and increase the permeability to oil. Due to high closure stress of the fractured formation, the conventional or uncoated proppants are easily crushed. Therefore, this project aims to increase the compressive strength of proppants by coating it with urethane based nanocomposite. Glass beads and fracking sands are coated with urethane resin and mixed with reduced graphene oxide (rGO) and carbon nanotubes (CNTs) respectively. Analysis testing using optical microscopy (OM) was conducted to study the morphology and microstructures of the coated proppants before and after crush test. Results showed remarkable improvement in proppants compression strength up to 41% and 35% after adding only 0.5% of CNTs and 0.1% of rGO respectively to the urethane resin coating. Therefore, it is recommended to utilize this material for coating the proppant with the optimized concentration to prevent pore plugging and proppant from flowing back, achieving the objective and solving both problem statements.

Noncovalent functionalized graphene nanoplatelets (GNPs) were successfully prepared with Gum Arabic as exfoliation solvent via an ultrasonication-assisted process to produce a highly dispersed material under high salinity and high temperature conditions. The implementation of the functionalization groups was validated with Fourier transform infrared spectroscopy and Transmission Electron Microscopy. The functionalized graphene nanoplatelets with Gum Arabic were dispersed in 3 wt.% high salinity brine with various concentrations to prepare Gum Arabic-GNP/brine nanofluids. The dynamic viscosity of the produced nanofluid at different concentrations was higher than that of crude oil at a high temperature (90 °C) and a high shear rate (1000 L/s). The functionalized graphene with Gum Arabic altered the wettability of sandstone from oil to water and changed the contact angle from 108° to 21° at 0.1 wt.%. Moreover, the value of contact angle reduced to 87% with presence 0.1 wt.% of GA-GNPs. These results are demonstrating that the GA-GNPs nanofluids could improve the mobility of the residual oil from the porous media to the production well with high efficiency of oil displacement.

In the attempt of preparing multi-walled carbon nanotube (MWCNTs), covalent functionalisation (CF-MWCNTs) were applied. The stable thermal conductivity was measured as a function of temperature. A number of techniques, such as FTIR, FESEM and UV-vis spectrophotometer were employed to characterise both dispersion stability and morphology of functionalised materials. By using ultrasonic test time, the highest stability of nanofluids was achieved at 60 minutes. As a result, the thermal conductivity displayed by CF-MWCNTs was higher than distilled water. In conclusion, improvement in thermal conductivity and stability displayed by CF-MWCNTs was higher, while the best thermal conductivity improvement was recorded at 31%.

This paper introduces an innovative alternative for spark sintering, in which contactless plasma sintering (CPS) is accomplished by means of plasma arc. In this arrangement, arc current will not pass through the sample to be sintered allowing sample to not contact the arc plasma electrodes. Consequently, this method provides continuous sintering. SiC whiskers was chosen to characterize sintering parameter. The SiC refined by ball-milling to promote densification. Characterization of Silicon Carbide (SiC) were carried out with Field Emission Scanning Electron Microscope (FESEM) and X-Ray Diffraction (XRD). The effect of the sintering-agent Fe addition on the sintered SiC-Fe composites were investigated based on the microstructure, densification.

Carbon nanotubes (CNTs) with its exceptional thermal and mechanical properties hold the promise of delivering high performance nanocomposite materials. To utilize CNTs as effective reinforcement in metal nanocomposites, appropriate dispersion and robust interfacial adhesion between individual CNT and metal matrix have to be certain. This work presents a novel combined technique of nanoscale dispersion (NSD) of functionalized multiwalled carbon nanotubes (MWCNTs) in copper (Cu) matrix composite followed by powder injection molding (PIM). MWCNTs contents were varied from 0 to 10 volume fraction. Evidences on the existence of functional groups and microstructural analysis of the fabricated nanocomposites were determined using TEM, EDX, FESEM and FTIR. Thermal conductivity and elasticity measurements were also performed. The results showed that the impurities of the pristine MWCNTs such as Fe, Ni catalyst, and the amorphous carbon have been significantly removed after sonication process. FESEM and TEM observations showed high stability of MWCNTs at elevated temperatures and uniform dispersion of MWCNTs in Cu matrix at different volume fractions and sintering temperatures (950, 1000 and 1050 � C). The experimentally measured thermal conductivities of Cu/MWCNTs nanocomposites showed remarkable increase (11.25% higher than pure sintered Cu) with addition of 1 vol.% MWCNTs, while the modulus of elasticity (Young’s modulus) of Cu/MWCNTs nanocomposites sintered at 1050 � Cf or 2hw asincreased

The performance of the micro-chip is affected by overheating and hence reduces the efficiency of electronic devices. The development of high thermal conductivity material can solve problems associated with dissipation of heat from the micro-chips. Thermal conductivity for carbon nanotubes (CNTs) are in the ranges of 1200-3000 W/moK which considered as the best candidate material for heat sink applications. This research investigates the fabrication of CNTs reinforced copper composites using powder metallurgy method. Copper powder and CNTs were ball milled to prepare mixtures and compacted at 600 MPa to fabricate test samples. The compacted test samples were sintered in argon atmosphere at 850oC. Sintered density of CNTs/Cu composites was measured and compared with theoretical density. Density data showed that 98% sintered density was achieved. Optical and scanning electron microscopic (SEM) examination of sintered compacts showed good grain growth, however porosity was also noted in sintered samples. Field emission scanning electron microscopy (FESEM) showed well dispersion of CNTs in copper matrix and interfacial bonding between copper particle and CNTs. In this experiment, the addition of 2 % vol. CNTs in copper matrix showed 9% increase in thermal conductivity approximately compared to thesintered pure copper.

Carbon nanotubes (CNTs) reinforced copper (Cu) matrix nanocomposites prepared via advanced fabrication method is presented. Functionalization and ultrasonication processes have been applied to enhance the dispersion of purified CNTs and creates sidewalls groups that have the potential to bond CNTs to the metal matrix. The main part of this approach was metal injection molding (MIM) technique, which is a combination of powder metallurgy and plastic injection molding technique. Preparation of MIM feedstock required a melting and mixing process of binder system (polymers) with the solid loading, which has been carried out using a twin screw rotor machine. This machine provides a viscous media of the molten binder with high shear forces that allow the additives (carbon nanotubes/copper powder) to be mixed properly and exfoliate the CNTs clusters with uniformdispersion inside the Cu matrix. Subsequently, to prove our expected results, observation tests of TEM, SEM, FESEM and CNTS were employed and discussed literally.

Uniform dispersion of carbon nanotubes (CNTs) in metal composites has been by far the most significant challenge in the field of CNT-reinforced metal matrices. This work presents a new dispersion and fabrication technique of Carbon nanotubes (CNTs) reinforced copper (Cu) matrix nanocomposites. A combination of nanoscale dispersion of functionalized CNTs in low viscose media of dissolved paraffin wax under ultrasonication treatment followed by powder injection molding (PIM) technique was adopted. CNTs contents were varied from 0 to 10 vol.%. TEM, EDX, FESEM and Raman spectroscopy analysis were used for materials characterization. Information about the degree of purification and functionalization processes, evidences on the existence of the functional groups, effects of ultrasonication time on the treated CNTs, and microstructural analysis of the fabricated Cu/CNTs nanocomposites were determined. The results showed that the impurities of the pristine CNTs such as Fe, Ni catalyst and the amorphous carbon have been significantly removed after purification process. Meanwhile, FESEM and TEM observations showed high stability of CNTs at elevated temperatures. It also showed an excellent homogeneous dispersion of CNTs in Cu matrix and led to a strong interfacial bonding between Cu particles and individual CNTs.

316L stainless steel is widely used in various industries due to low cost, ease of availability and exceptional combination of mechanical properties along with corrosion resistance as compared to the other available metal alloys. In powder injection molding, debinding is very critical step and improper debinding can change the final properties dramatically. In the present study, affects of debinding on mechanical properties of powder injection molded 316L stainless steel were studied. The prepared feedstocks were molded according to MPIF 50 standard using vertical injection molding machine (KSA100). The plastic binder was removed at 450°C from the molded test samples using two different furnaces i.e. commercial and laboratory furnace followed by the sintering in vacuum, hydrogen, mixture of H2 and N2 (9:1) and nitrogen at 1325°C for 2hr with post sintering cooling rate 3°C/min . Test samples debound in commercially available furnace showed 97% densification and higher mechanical properties. The corrosion resistance was reduced due to presence of residual carbon during thermal debinding. The presence of carbon and formation of carbides and nitrides were confirmed by XRD and microstructural analysis. The results showed that the test samples debound in commercial furnace showed brittle behavior due to the presence of carbides and nitrides. Test samples sintered in N2 showed 96.3% density and tensile strength 751MPa. This value of strength is twice as compared to the sample debound in laboratory furnace followed by the sintering in vacuum. The achieved mechanical properties in vacuum sintered samples were comparable to the wrought 316L stainless steel (according to ASTM standard).

Drilling fluid which is also known as drilling mud is a crucial element in oil and gas exploration process as it used to aid the drilling of boreholes into the earth. Among other functions, drilling fluid needs to carry drill cuttings to the surface of the well, support the walls of the well bore, provide hydrostatic pressure to prevent formation fluids from entering into the well bore, cool and lubricate the drill bit, prevent drill-pipe corrosion, facilitate the attainment of information about the formation being drilled, and create a thin low-permeability cake that protects permeable production formations. Water-based mud (WBM) is the most common drilling fluid used in oil industry. WBM is an expensive complex chemical system that is usually mixed with filtration-loss-prevention additives such as clay, lignite, or organic polymers, with bentonite clays being very common to control the fluid-loss during drilling process. These traditional additives are able to give an average fluid loss of 7.2 mL over 30 min and leaving a filter cake ∼280 μm thick. Graphene, as a single layer of graphite which is also considered nano-additive, has become the subject of much research interest for its unique materials properties. A pristine graphene monolayer has a theoretical surface area of 2965 m2/g and has been shown to form a membrane impermeable even to helium gas. This work presents the recent progress of using nano-materials such as graphene as an additive in WBM. Most recent report showed that graphene has the potential to decrease the fluid loss by ∼15–20% (due to its large surface area with very thin 2D layer, only 1 atom thick) compared to that of WBM with conventional additives, and to reduce the filter cake thickness up to ∼20–50 μm, which in turn can help to increase the oil production rate. In addition, adding graphene to WBM solutions is expected to lead to greater shear thinning and higher temperature stability compared to clay-based fluid loss additives.

The microstructure of photoelectrode plays a crucial role in the performance of Dye Sensitized Solar Cells (DSSCs). The uneven morphology of FTO (Fluorine doped tin oxide) glass and high porosity of TiO2 layer will produce defects such as tiny gaps, pores and cavities in FTO/TiO2 interface which allows for direct penetration of the electrolyte to the surface of FTO, leading to the recombination of electrons. To address this issue some work has been conducted to functionalize FTO glass with graphene because of its exceptional mobility and transparency. However, this approach is not feasible as graphene nanosheets is economically quite expensive. Therefore, in the current study, graphene nanosheets is replaced with graphene nanoplatelets (GNPs) in order to modify the FTO/TiO2 interface by providing conducting bridges to photo-injected electrons and impede the excessive penetration of the electrolyte. The conversion efficiency for GNP modified interface was found to be 2.32 % (active area of 1 cm2), which is...

Austenitic Stainless Steel Has a FCC Structure at Room Temperature and the Temperature Range of the Austenite Phase Depends upon its Composition. 316L SS Is Widely Used in Medical, Marine, Industrial, Sporting and Aerospace Applications due to its Excellent Combination of Mechanical Properties and Corrosion Resistance. this Study Presents the Defects Observed during Optimization of the Processing Parameters for the Fabrication of Powder Injection Molding (PIM) of 316L SS Parts. in this Study, Five Formulations of Feedstock Containing 60-71vol% of Metal Powder Were Prepared Using a Wax-Based Binder. Green Samples Were Injection-Moulded, Followed by Binder Removal by Solvent and Thermal Means. Paraffin Wax (major Binder) Was Extracted at Various Temperatures in Order to Determine the Solvent Extraction Temperature. the Thermal De-Binding Was Performed Successfully at a Temperature of 450°C by Varying the Heating Rate from 1°C/min -10°C/min. SEM Results Showed Complete Removal of the Plastic Binder. Test Samples Were Sintered at Various Temperatures and Atmospheres. the Defects Observed during Solvent Extraction Were Swelling, Cracks and, at the Thermal De-Binding Step, Collection of Binder, Swelling and Holes. Sintered Samples Showed a Loss of Dimensional Control. these Types of Defect Were Considered to Be due to Inappropriate Heating Rates, Temperature and Dwell Time at each Process Step.

This research presents the effects of temperature and cooling rate on mechanical properties of powder injection molded 316L Stainless steel. Steel powder and binder were mixed together to produce the feedstock. The green samples were produced by injection molding and debinded. Brown test samples were sintered in vacuum at 1325°C, 1360°C and 1380°C for 2h with two heating and cooling rates 5°C/min and 10°C/ min. The test samples sintered at 1325°C achieved maximum sintered density. The higher cooling rate improved the strength of the sintered test samples. The maximum sintered density of 96% and tensile strength of 503MPa was achieved and these results are comparable to the wrought 316L stainless steel (according to ASTM standard).

Metal injection molding (MIM) technology is known for its ability of producing near net shape components. This study presents the results of flow behavior of multi-walled carbon nanotubes (MWCNTs) reinforced copper composites mixes. The solid loadings in the copper mixes were investigated in the ranges of 55-61 V% using a binder. Copper mixes and copper/MWCNTs were compounded using a Z-blade mixer for homogenous dispersion of solids in the binder. Results identified a mix containing 59 V% copper suitable for substitution of MWCNTs. The flow properties were measured using a capillary rheometer in the shear rate range expected to occur during metal injection molding. An increasing trend in viscosity of the copper mixes with powder loading was noted. Copper/MWCNTs composite mixes showed viscosity more than 1000 Pa.s perhaps due to addition of MWCNTs and increasing trend in viscosity of copper/MWECNTs was recorded. The results of flow data showed that all copper composite mix containing up to 10 Vol.% MWCNTs were successfully injection molding and test samples were produced.

— In this study, the flow behavior of multi-walled carbon nanotubes (CNTs) reinforced copper matrix feedstocks isp resented. The solid loadings in the copper feedstock were investigated in the ranges of 55-61 Vol. % using binder. Pure copper (Cu) and Cu/CNTs feedstocks were compounded using internal mixer machine for homogenous dispersion of solids in the binder. The flow behavior was measured using a capillary rheometer in the shear rate range expected to occur during powder II.injection molding. An acceptable increasing trend in viscosity of the copper feedstock with powder loading was recroded. Cu/CNTs composite feedstocks showed viscosity more than 1000 Pa.s which is most probably due to the addition of CNTs and increasing trend in viscosity of Cu/CNTs was noted as well. The results also identified that the feedstock containing 59 vol. % copper was most suitable for substitution of CNTs in Cu feedstock.

Predictions are reported for mixed convection using various types of nanofluids over forward-facing double steps in a duct. The continuity, momentum and energy equations are discretized and the simple algorithm is applied to link the pressure and flow fields inside the domain. Different types of nanoparticles Al2O3, CuO, SiO2 and ZnO, with different volume fractions in range of 1-4% are investigated to identify their effects on the heat transfer and fluid characteristics. Numerical investigations are conducted using finite volume method. The results indicate that SiO2 -water has the highest Nusselt number followed by Al2O3-water, CuO -water and ZnO-water. The Nusselt number increases as the volume fraction increases but decreases as the nanoparticles diameter increases.

The tensile properties of short fiber reinforced composites are enhanced if fiber alignment in the load direction is achieved. Powder injection molding provides partial alignment of fibers in molded parts and shows a skin-core effect. The objective of this study was to align fibers completely in flow direction and reducing skin-core effect in green samples. This objective was achieved by changing the type of flow during molding by changing sprue geometry in a way that diverging flow is developed in it. This diverging flow was converted to converging flow when feedstock entered mold cavity and generated shear to align fibers. This sprue modification was helpful in aligning short fibers in flow direction and eliminating skin-core effect.

Powder injection molding (PIM) offers an attractive method for producing smart and intricate shapes components. PIM process is cost effective and equally applicable for metals and ceramics. Debinding process is the most critical step among all PIM steps and any residual during debinding can change the composition of sintered product resulting change in final properties. In this research work, the injection molded samples were thermally debound and sintered in various atmospheres. The results showed that the sintered samples with improper thermal debinding resulted the carbide formation at the surface and across the grain boundaries that caused to increase the roughness value.

The thickness of photoanode is crucial as it adsorbed a large amount of dye molecules that provide electrons for generation of electricity in dye sensitized solar cell (DSC). Thus, in order to realize the practical application of DSC, study on various thickness of photoanode need to be carried out to analyze its effect on the electrochemical behavior of dye sensitized solar cell. To enhance the conversion efficiency, an additional layer of TiO2 using TiCl4 treatment was deposited prior to the deposition of the photoanode (active area of 1cm2) with the thickness of 6, 12, 18, 24, and 30 µm on fluorine doped tin oxide (FTO) glass substrate. The resulting photoanode after the soak in N719 dye for more than 12hrs were used to be assembled in a test cell in combination with liquid electrolyte and counter electrode. The fabricated cells were characterized by solar simulator, ultraviolet-visible spectroscopy (UV-VIS), and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) was used t...