Structural characteristics and sodium penetration behaviors in anthracite cathodes: a combination study using Monte Carlo and molecular dynamics simulations

Daoush Walid M.,Li Jiaqi,Zhang Hongliang,Li Tianshuang,Xiao Jin 한국탄소학회 2020 Carbon Letters Vol.30 No.3

In aluminum electrolysis, sodium penetration into carbon cathodes is considered as the main cause of cell failure and ef�ciency loss, but the detailed mechanism is still not defnitely clear. Since the macroscopic properties of material depend on the microscopic structures, a large-scale atomistic model of anthracite cathodes was constructed to represent several important structural characteristics. Combined with Monte Carlo and molecular dynamics simulations, the adsorption and difusion behaviors of sodium were investigated, respectively. The results suggest that sodium adsorption mainly occurs in the larger micro-pores with the range of 10–19 Å, while it accords well with to type-I Langmuir adsorption model. The sodium is found to be preferentially adsorbed in arch-like structures with 5- or 7-membered rings or around heteroatom, especially oxygen. Moreover, the movements of sodium through carbon matrix mainly depend on the continuous difusive motion while most sodium particles tend to be trapped in voids with small mobility. The calculated transport difusion coefcient is equal to 6.132 × 10−10 m2 /s, which is in outstanding agreement with experimental results. This fundamental research would contribute to the understanding of sodium penetration mechanism and the optimization of cathode industry in the f

Electrical and mechanical properties of carbon nanotube reinforced copper nanocomposites fabricated by electroless deposition process

Daoush, Walid M.,Lim, Byung K.,Mo, Chan B.,Nam, Dong H.,Hong, Soon H. Elsevier 2009 Materials science & engineering. properties, micro Vol.513 No.-

<P><B>Abstract</B></P><P>Multiwalled carbon nanotube/copper (CNT/Cu) nanocomposite powders with different CNTs volume fractions were prepared by electroless Cu deposition on the CNTs. The CNTs underwent acid treatment, sensitization and electroless copper deposition on their surface respectively. The microstructure of the prepared CNT/Cu nanocomposites was investigated by SEM and HRTEM as well as by XRD analysis. Copper was deposited in a form of a layer on the CNTs surface. The CNT/Cu nanocomposite powders were sintered by spark plasma sintering. The microstructure of the sintered materials were investigated by SEM indicating that the CNTs were homogenous distributed in the copper matrix with good sinterability and porosity content lower than unity in case of 5 and 10vol.% of CNT/Cu nanocomposites and 2.9 and 3.5% respectively for 15 and 20vol.% CNT/Cu nanocomposites. The electrical conductivity, hardness and the tensile properties were measured for evaluating the sintered CNT/Cu nanocomposites. The electrical conductivity decreased by increasing CNTs volume fraction in copper matrix, but the hardness was increased by increasing CNTs volume fraction. The Young's modulus was increased and the elongation was decreased by increasing the volume fraction of CNTs in copper matrix. In addition, the yield strength of the sintered materials was increased by increasing CNTs volume fraction except in case of 20vol.% CNT/Cu composite the material was fractured before yielding.</P>

Microstructure and electrical properties of carbon short fiber reinforced copper composites fabricated by electroless deposition followed by powder metallurgy process

Daoush Walid M.,Alkhuraiji Turki S.,Khamis Moath A.,Albogmy Turki S. 한국탄소학회 2020 Carbon Letters Vol.30 No.3

Carbon short fbers/copper composites with diferent carbon short fber contents up to 15 wt.% as reinforcements are prepared to investigate the infuence of the carbon short fber surface coating on the microstructure, density, and electrical properties of the carbon short fbers/copper composites. The carbon short fbers were surface treated by acid functionalization followed by alkaline treatment before the coating process. It was observed from the results that coated type copper nanoparticles were deposited on the surface of the carbon short fbers. The surface treated carbon short fbers were coated by copper using the electroless deposition technique in the alkaline tartrate bath by using formaldehyde as a reducing agent of the copper sulfate. The produced coated carbon short fbers/copper composite powders were cold compacted at 600 MPa, and then sintered at 875 °C for 2 h under (hydrogen/nitrogen 1:3) atmosphere. A reference copper sample was also prepared by the same method to compare between the properties of pure copper and the carbon short fbers/copper composites. The phase composition, morphology, and microstructure of the prepared carbon short fbers/copper composite powders as well as the correspond�ing carbon short fbers/copper composites were investigated using X-ray difraction analysis (XRD) and scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS), respectively. The density and the electrical resistivity of the sintered composites were measured. It was observed from the results that the density was decreased; how�ever, the electrical resistivity was increased by increasing the carbon short fbers wt.%.

Fabrication and characterization of Copper/Silicon Nitride composites

Ahmed, Mahmoud A.,Daoush, Walid M.,El-Nikhaily, Ahmed E. Techno-Press 2016 Advances in materials research Vol.5 No.3

Copper/silicon nitride ($Cu/Si_3N_4$) composites are fabricated by powder technology process. Copper is used as metal matrix and very fine $Si_3N_4$ particles (less than 1 micron) as reinforcement material. The investigated powder were used to prepare homogenous ($Cu/Si_3N_4$) composite mixtures with different $Si_3N_4$ weight percentage (2, 4, 6, 8 and10). The produced mixtures were cold pressed and sintered at different temperatures (850, 950, 1000, $1050^{\circ}C$). The microstructure and the chemical composition of the produced $Cu/Si_3N_4$ composites were investigated by (SEM) and XRD. It was observed that the $Si_3N_4$ particles were homogeneously distributed in the Cu matrix. The density, electrical conductivity and coefficient of thermal expansion of the produced $Cu/Si_3N_4$ composites were measured. The relative green density, sintered density, electrical conductivity as well as coefficient of thermal expansion were decreased by increasing the reinforcement phase ($Si_3N_4$) content in the copper matrix. It is also founded that the sintered density and electrical conductivity of the $Cu/Si_3N_4$ composites were increased by increase the sintering temperature.

Application of Taguchi method in optimization of process parameters of ODS tungsten heavy alloys

Sayed, Mohamed A.,Dawood, Osama M.,Elsayed, Ayman H.,Daoush, Walid R. Techno-Press 2017 Advances in materials research Vol.6 No.1

In the present work, a design of experiment (DOE) technique using Taguchi method, has been applied to optimize the properties of ODS tungsten heavy alloys(WHAs). In this work Taguchi method involves nine experiments groups for four processing parameters (compaction pressure, sintering temperature, binding material type, and oxide type) with three levels was implemented. The signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were employed to obtain the optimal process parameter levels and to analyze the effect of these parameters on density, electrical conductivity, hardness and compressive strength values. The results showed that all the chosen factors have significant effects on all properties of ODS tungsten heavy alloys samples. The density, electrical conductivity and hardness increases with the increase in sintering temperature. The analysis of the verification experiments for the physical properties (density and Electrical conductivity) has shown that Taguchi parameter design can successfully verify the optimal parameters, where the difference between the predicted and the verified values of relative density and electrical conductivity is about 1.01% and 1.15% respectively.