Advanced Materials Research Vol. 409

Abstract: Metal orthogonal cutting process involves complex geometry deformation and mate-rial characteristics as large thermal-visco-plastic ow include ductile damage. Simultaneously,the contact with friction occurs in the same zone. To build the nite element model for metalcutting, the nite element mesh will be severely distorted at the region with high gradientof stress/strain/temperature eld. In this paper, a Adaptive remeshing procedure which inte-grates the 3D OPTIFORM mesher, ABAQUS/Explicit solver and eld node-node eld transferalgorithm are proposed to solve these problems. The thermal-mechanical simulation for metalorthogonal cutting is realized to demonstrate our numerical simulation approach. Some simu-lation results are illustrated include continuous chip forming process, thermal-mechanical elddistribution and cutting force in di erent rank angles, cutting speeds and friction conditions.

Abstract: Oxide nanoparticles have tremendous technological applications in the present days in diverse fields. In this study, the surface modification and functionalization of hydrophilic silica (SiO₂) and zinc oxide (ZnO) nanoparticles were performed to obtain superhydrophobicity. Monodispersive nanoparticles of SiO₂ were prepared by Stöber process using tetraethoxysilane (Si (OC₂H₅)₄) as a precursor and ammonium hydroxide as a catalyst in a ethanolic solution. The surface modification of the silica nanoparticles were performed using fluoroalkylsilane (FAS-17: C₁₆H₁₉F₁₇O₃Si) molecules to obtain fluorinated silica nanoparticles of diameter varying from 50nm to 300nm. On the other hand, surface modification of zinc oxide (ZnO) nanoparticles was performed using stearic acid (C₁₈H₃₆O₂) molecules to obtain methylated ZnO nanoparticles. These functionalized nanoparticles were characterized both in the form of powder as well as thin films. The bonding characteristics of FAS-17 molecules with SiO₂ and stearic acid molecules with ZnO were investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Nanostructured thin films of these functionalized oxide nanoparticles exhibit superhydrophobicity with contact angles over 150° with water roll-off properties. Such functionalized oxides nanoparticles, therefore, can be easily incorporated in coatings and paints for various applications in emerging technologies like biomedical applications, anti-corrosion, anti-icing, drag reduction and energy consumption reduction.

Abstract: Monolithic and multilayered iron electrodeposits were successfully synthesized by the pulse plating electrodeposition method. Electron microscopy and Vickers microhardness measurements were used to investigate the microstructure and mechanical properties of the iron electrodeposits produced. Two types of monolithic iron coatings were produced, one with a coarse grained, columnar structure and the other with an ultra-fine grained structure. Hall-Petch type grain size strengthening was observed in these monolithic coatings. Multilayered iron coatings composed of alternating layers of coarse grained and fine grained structures were also produced. The hardness value of the multilayered coatings falls between the hardness values for the two types of monolithic coatings produced. This study has demonstrated the possibility of applying a multilayered structure design to tailor the microstructure and mechanical properties of electrodeposited iron coatings.

Abstract: Commercially available polycrystalline nickel (grain size: 30 µm) and electrodeposited nanocrystalline nickel (grain size: 30 nm) were analyzed for the effect of stress-induced heat generation during plastic deformation at room temperature. Tensile coupons in conformance to ASTM E8 standard were tested at a strain rate of 10^-1/s to record the amount heat dissipated using a high resolution infrared detector. The maximum temperature increases recorded for nanocrystalline and polycrystalline nickel close to sample fracture were 58°C and 70°C, respectively. Grain growth in nanocrystalline nickel due to stress-induced heat generation is unlikely since the maximum temperature during deformation is below the previously reported onset temperature for grain growth in nanocrystalline nickel.

Abstract: Pure nanostructured LaFeO₃ with crystallite size of around 13 nm and specific surface area of 48 m²/g were prepared using high energy ball milling. 0.4, 2 and 5 wt% of Pd was impregnated on synthesized LaFeO₃. TPD-O₂, TPD-CO and TPR-H₂ were performed to find the effect of Pd loading on perovskite oxide properties.CO gas sensing properties of doped and pure formulation were investigated. These results showed that 2 wt% Pd had optimum response ratio which had a maximum response ratio of 1200% with respect to 100 ppm CO in air at 140°C.

Abstract: Layered perovskite (RNH₃)₂PbI₄ (R = organic cation), which contained the fullerene derivatives, [ethyl-3-tert-butoxycarbonylaminopropyl (1,2-methanofullerene C₆₀)]-61,61-di carboxylate iodide (EAF-I) and di [3-tert-butoxycarbonylaminopropyl (1,2-methanofullerene C₆₀)]- 61,61-dicarboxylate diiodide (DAF-I₂) in the organic layers were fabricated and compared with previously reported perovkite compound containing N-methyl-2-(4-aminophenyl)-fulleropyrrolidine iodide (AmPF-I). Because the solvent solubilities of EAF-I and DAF-I₂ to N,N-dimethylformamide (DMF) were higher than AmPF-I, the film processability of EAF-I and DAF-I₂ was improved compared with AmPF-I. The X-ray diffraction patterns proved the construction of the perovskite structure in (EAF)₂PbI₄ and (AmPF)₂PbI₄ cast films. EAF was well-organized and closer-packing than AmPF in the perovskite structure. For the diamine-type fullerene, DAF-I₂, it is difficult to form layered structure by spin-coated or cast methods. New sharp X-ray diffraction peaks were observed for DAF-I₂ films dipped in PbI₂ solution. The intercalations and formation of perovskite structure of (DAF)PbI₄ were studied.

Abstract: Preparation of nanostructured superhydrophobic surfaces requires both an optimum roughness and low surface energy. Application of a direct voltage between two copper plates immersed in a dilute ethanolic stearic acid solution transforms the surface of the anodic copper electrode to superhydrophobic due to the formation of micro-nanofibrous low surface energy flower-like copper stearate as confirmed by scanning electron microscope (SEM). Nanostructured superhydrophobic aluminum surfaces have also been prepared by electrodeposition of copper films on aluminum surfaces followed by electrochemical modification by ethanolic stearic acid. The X-ray diffraction (XRD) analyses confirmed the formation of copper films on aluminum substrates. The electrodeposited copper films are composed of microdots of copper whose density increases with the decrease of deposition potential as observed by SEM. The deposited copper microdots on aluminum substrates were electrochemically modified to low surface energy copper stearate nanofibres to obtain superhydrophobicity. The copper films deposited at potentials above-0.6 V did not exhibit superhydrophobic properties. However, the copper films deposited at potential-0.6 V and below exhibited superhydrophobic properties with water drop rolling-off those surfaces.

Abstract: Polythiophene derivatives containing a phosphonate ester group, poly [3-(3-diethyl-phosphonate) propoxythiophene] (PEPPT), were synthesized by Rieke and oxidative polymerization methods. These PEPPTs were soluble in polar organic solvents such as methanol, DMF, and chloroform. The head-to-tail ratio of PEPPT (Rieke) was estimated to be 98 % by ¹H NMR spectroscopy, while that of PEPPT (Oxidative) was estimated to be 53 %. The maximum absorption peak of PEPPT (Rieke) was observed at 596 nm, which was 46 nm longer than that of PEPPT (Oxidative) in CHCl₃ solutions. This result suggests that the planarity of PEPPT (Rieke) is higher than that of PEPPT (Oxidative) due to the high regioregularity of the side chains. The estimated band gap of PEPPT was 1.60 eV for Rieke-synthesized derivatives. The XRD peak of PEPPT(Rieke) was observed at 5.14º (17.2 Å) and that of PEPPT (Oxidative) was not clearly observed, suggesting that PEPPT(Rieke) has self-organized properties to form a layered structure.

Abstract: All-printed electronics as a mean of fast processing and achieving ultra-low-cost electronic devices has attracted great interest in recent years. Inkjet printing has excelled as the most promising technique by which the circuit components can be directly drawn on the specific area in one step. Furthermore, the low temperature reduction processes can be achieved by exploit the low-melting point characteristic of nanometallic particles. The inkjet printing technique to deposit silver nanoparticles (3.39±1.21 nm) capped by saturated 3-Mercaptopropionic acid onto silicon substrate was studied. The silver patterns were tested for its functionality as circuit components like conductor, resistor and capacitor. All components can be produced simply by thermal annealing of an inkjet printed patterns under an atmosphere of 90% N₂-10% H₂ at 300°C for 1 hr.

Abstract: A strong push has been observed in the automotive industry to replace current components with high-performance and lightweight materials such as aluminum alloys. Novel monolithic materials such as bulk nanostructured materials, cannot always offer the best performance in hostile environments and often have high manufacturing costs. This has required the development and engineering of processes to allow nanostructured surface functionalization of conventional materials. This processing strategy, similar to the metal-ceramic joining approach, exploits the advantages of both materials while reducing overall manufacturing costs. Spark Plasma Sintering (SPS) will be evaluated as potential a method for manufacturing a nanostructured Al-Si cladding. This novel coating method has a significant advantage over traditional processes in that it forms metallurgical bonds at both the interface and throughout the deposited layer to produce a coating with isotropic properties. The objective of this work is to create a nanostructured eutectic Al-Si feedstock powder and simultaneously consolidate and clad the powder onto a forged aluminum substrate using Spark Plasma Sintering. Results show that after mechanical milling, the aluminum grain size was refined to 47nm. The results also show that SPS is capable of sintering the powder in extremely short sintering times while maintaining nanostructure, and that the heating rate has a large effect on increasing densification rates. Mechanical properties of the resultant coating were also investigated.