Papers by Keyword: Nano-Scale

Abstract: The performance prediction of C-S-H gel is critical to the theoretical research of cement-based materials. In the light of recent computational material technology, modeling from nano-scale to micro-scale to predict mechanical properties of structure has become research hotspots. This paper aims to find the inter-linkages between the monolithic "glouble" C-S-H at nano-scale and the low/high density C-S-H at the micro-scale by step to step method, and to find a reliable experimental verification method. Above all, the basic structure of tobermorite and the "glouble" C-S-H model at nano-scale are discussed. At this scale, a "glouble" C-S-H structure of about 5.5 nm3 was established based on the 11Å tobermorite crystal, and the elastic modulus ​​of the isotropic "glouble" is obtained by simulation. Besides, by considering the effect of porosity on the low/high density of the gel morphology, the C-S-H phase at micro-scale can be reversely characterized by the "glouble". By setting different porosities and using Self-Consistent and Mori-Tanaka schemes, elastic moduli of the low density and high density C-S-H ​​from that of "glouble" are predicted, which are used to compare with the experimental values of the outer and inner C-S-H. Moreover, the nanoindentation simulation is carried out, where the simulated P-h curve is in good agreement with the accurate experimental curve in nanoindentation experiment by the regional indentation technique(RET), thus the rationality of the "glouble" structure modeled is verified and the feasibility of Jennings model is proved. Finally, the studies from the obtained ideal "glouble" model to the C-S-H phase performance has realized the mechanical properties prediction of the C-S-H structure from nano-scale to micro-scale, which has great theoretical significance for the C-S-H structural strengthening research.

Abstract: Corrosion of carbon steel in CO₂ saturated NaCl solution contains the formation of FeCO₃, as a corrosion product. The protective property of the formed FeCO₃ scale layer to corrosion in brine solutions containing CO₂ was established as the possible cause of the corrosion rate decrease above 60 °C. In this study, formation of nanoscale FeCO₃ film as a corrosion product of X52 carbon steel in CO₂-Saturated 3% NaCl solution was investigated. Result showed that corrosion rate decreased after precipitation and formation of protective FeCO₃ film in high temperature and high bulk solution pH.

Abstract: This paper reports the outcome of the laboratory investigation conducted on new clay liners modified with kaolinite combined with various content of lime-treated, various content of bentonite and admixture of kaolinite adding with 3% nano-kaolinite for composition. The 3% nano-kaolinite was chosen based on earlier finding by S.V.Netethu (2013). The various content of lime-treated and bentonite adopted are 2.0%, 5.0%, 7.5% and 10.0% by total weight of the kaolinite. Compaction tests was performed on the resulted modified clay liner samples to evaluate the best percentage that gives optimum moisture content (OMC) and maximum dry density (MDD) . The best percentage of each bentonite and lime-treated are chosen and be added into kaolinite and the physical properties of samples are tested and compared to the other two samples which are kaolinite only and kaolinite added with 3 % of nano-kaolinite. Nano-kaolinite was produced using a mill machine and the sized of nano-kaolinite (1nm-100nm) were examined under Scanning Electron Microscope (SEM) machine.The addition of 3% nano-kaolinite to the kaolinite gives the best compaction result compared to bentonite or lime-treated. The value of dry density is increased to give the reduction of air voids, thereby reducing the hydraulic conductivity by concept. Based on the compaction test value, it clearly observed that admixture of kaolinite adding with 3% nano-kaolinite gives the best results from the other samples due to required less water to achieve maximum dry density of 1.39 Mg/m³ and 27.34% of optimum moisture content resulted positive effect in soil properties.

Abstract: The modifiers of nano-SiC and nano-TiN were added into the melt of ZGMn13Cr2 alloy, respectively. The effect of the additions on the microstructure and mechanical properties were investigated. Results show that the two kinds of nano modifiers both have refining effect and make the improvement of impact toughness and wear resistance.

Abstract: The experiment of mechanical characteristics of sliding contact in nano-scale was researched using nano-indenter. The displacement-friction curves with different loads and sliding velocities were given through the contact effect between diamond indenter and mono-crystalline silicon test-coupon. The three-dimensional AFM morphologies were obtained through scanning contact area by AFM. The research shows that the contact-force and friction increase along with the increment of loads, in condition of sliding with different loads. The friction increases along with the increment of sliding velocity, in condition of different sliding velocities. Otherwise, furrow destruction along with obvious plastic flow is generated with low sliding velocity (100μm/s). However, the oddments accumulate obviously on the verge of nick with high sliding velocity (above 100μm/s), and the phenomenon of oddments accumulating is more obvious along with the increment of sliding velocity.

Abstract: A Newly Designed Cross-Shaped Electrode Tool and the Use of Excimer Irradiation to Assist in Micro-Electrochemical Etching (μ-ECE) Is Presented. It Is a Precise Surface Treatment Method for the Nanoscale Removal of Defective Indium-Tin-Oxide (In2O3SnO2) Conductive Nanostructure from Optical PET-Diaphragms (PET) of Digital Paper Touch-Panels. in the Current Study, 172nm Excimer Irradiation Is Used to Boost the Electrolytic Action of the Cross-Shaped Electrode Tool. Scoring of the PET Surface Is Eliminated and the Workpiece (PET) Feed Rate Can Be Higher with a Consequent Reduction in Production Costs. when Excimer Irradiation Is Used the In2o3sno2 Thin-Films Are More Easily Broken up and the Nano-Particles Escape from the PET Substrate Quickly and Cleanly. The Required Machining Time Is Shortened if Excimer Irradiation Is Used before the Electrochemical Removal Processing (μ-ECE) of the In2O3SnO2 Layer.

Abstract: This study used the nanoindenter to perform indentation tests on copper bulk and nano copper film in order to discuss the mechanical properties of pure copper at the nano scale. This study tested 7 levels of load, ranging from 20 to 200 μN (load increment at 30 μN) for the indentation tests on copper bulk and nano copper film specimens. Results showed that the load was roughly proportional to the residual depth, in the case of flat nano copper film, while the relationship between the load and the residual depth was not significant in the case of unsmooth copper bulk. Moreover, the hardness of both the copper bulk and the nano copper film would increase along with increasing load, while the Er value change trends of both the copper bulk and the nano copper film specimens differed with increasing load.

Abstract: In nano scale, the degradation failure mechanism for CMOS device such as hot-carrier injection, breakdown of thin oxides, electro-migration and NBTI (Negative Bias Temperature Instability) induced damage become a major reliability concern. Physics-of-Failure method is used in lifetime prediction of nano scale CMOS, which integrates loading condition, package, geometry and material with time-to-failure. Common lifetime models for these mechanisms are described and a method to estimate lifetime of nano-scale CMOS device, with simulation based on Physics-of-Failure. Through Failure Mode, Mechanism and Effect Analysis, failure mechanism and lifetime models are clarified and selected, as well as structure, material, processing parameters and environment conditions. Stress analysis, which includes electrical stress by EDA and thermal analysis by FEA (Finite Element Analysis) are carried out to acquire parameters in lifetime model. Damage accumulation algorism and competing theory are utilized to predict lifetime of the device. This method will help CMOS device design engineers better understand the failure mechanisms in nano-scale and take design-for-reliability measures.

Abstract: Nano-scale hydroxyl magnesium silicate was synthesized successfully by using hydrothermal method. The composition of as-prepared powder was proved chrysotile which adheres to monoclinic crystal system (a kind of hydroxyl magnesium silicate) by using X-ray Diffraction (XRD) technology. The morphology and microstructure of chrysotile powder were characterized by using scanning electron microscope (SEM) and transmission electron microscope (TEM). Nano-particles and nano-rods were observed in SEM micrograph. Moreover, smaller-size nano-particles and nano-fibres were observed by using TEM. Based on results of SEM and TEM, the growth mechanism of chrysotile powder under hydrothermal conditions was discussed.

Abstract: The corrosion behavior of a nanocrystalline (NC) low carbon steel (LCS) surface film deposited on a conventional polycrystalline (PC) LCS by magnetron sputtering was studied in 0.5 M H2SO4 solution using impedance and potentiodynamic polarization techniques. The corrosion inhibiting effect of a non toxic organic compound (methionine) and synergistic KI additives was also studied. Microstructure characterization by X-ray diffraction and atomic force microscopy revealed no phase changes due to nanoprocessing and the grain size of the NC surface layer was ~ 40 nm. Electrochemical results show that both the PC and NC surfaces underwent active corrosion with no transition to passivation in the potential range studied. Surface nanocrystallization however increased the corrosion susceptibility of low carbon steel more than two-fold, leading to a decrease in interfacial impedance and an increase in the kinetics of the anodic reaction. Methionine inhibited the corrosion of both specimens with comparable inhibition efficiencies. Iodide ions synergistically increased the inhibition efficiency of methionine on both specimens. This synergistic effect was more pronounced for the bulk steel and has been discussed vis-à-vis the more positive surface charge on bulk steel surface at the corrosion potential compared to the nanocrystalline surface.