Advanced Materials Research Vol. 716

Abstract: Zr1 Nb1 Sn0.2 Fe alloy exhibited the transition of the stress exponent from 6.5 to 7.5 in the lower stress region to 4.2 in the higher stress region. The reduction of stress exponent at high stresses in Zr1 Nb1 Sn0.2 Fe can be explained in terms of the dynamic solutedislocation effect. The temperature range of dynamic strain aging generally increases with increase of strain rate. The dynamic strain aging due to oxygen atoms observed in Zr alloys at temperatures between 300°C and 400°C during tensile test at the strain rate of 1 x10^-3/sec should occur below 300°C in creep because the creep rates (1 x 10^-6 and 1 x10^-8) are much lower. Since solute atoms which can act as mobile obstacles are Sn and oxygen, the solute-dislocation interaction for the strengthening of creep resistance at intermediate temperatures is likely caused by Sn atoms. Dislocation networks and pile-ups around the precipitates were observed at the applied stress of 80MPa. And dislocations were observed to be distributed more or less randomly at the applied stress of 120 MPa. The more homogeneous distribution of dislocation in the region of low stress exponent at 120 MPa is thought to be caused by the dynamic strain aging effect of Sn atoms.

Abstract: 3Dimensional Integration can solve many challenges which are being faced by modern planer integration. The major bottleneck of 3D-Integration are contamination and Copper surface oxidation which is the cause of the requirement of high temperature while bonding. Reduction of this high bonding temperature is the key challenge of 3Dimensional Integration. In this research work we investigate and compare the Copper surface protection characteristic of Self-Assembled Monolayer (SAM) of Alkyl Thiol having different Carbon chains (C₆,Hexanethiol and C₁₂, Dodecanethiol). We also study the thermal desorption of these SAM layers. SAM can minimize the oxidation of the Copper which acts as a bonding medium. By thermal desorption the pure Copper surface is brought back and exposed. Finally Copper-Copper thermocompression bonding is performed in different conditions and compared.

Abstract: Zinc Crystal Glaze has its limits in practical use of commercial glaze due to the sensitive firing schedule. In order to overcome these limits, and to improve the practical usage, this study is aimed to develop a stable zinc crystalline glaze. This study altered the quantity of nuclear formation of zinc crystal glaze in order to control the willemite (Zn₂SiO₄) formation in the glaze. The addition of ZrO₂ to zinc crystal glaze influences the quantity of nuclear formation and its preservation; thus ZrO₂ was used to control the optimal firing temperature and the size of the crystal formation in the glaze to find a zinc crystal glaze capable of withstanding various ranges of temperatures.

Abstract: Lanthanum-doped anatase TiO₂ coatings, which are composed of assemble crystalline of 50 nm diameter particles, when the percentage of dopant is 0.5 wt%, have been successfully fabricated by solgel dip-coating process on light leakage silica fiber (LSF) which length is 15cm and diameter is 125μm. This was achieved by adjustment of the lanthanum-doped solgel parameters such as molar ratio of precursors in lanthanum-doped TiO₂-sols, the ratio of titanium tetrabutoxide to polyvinyl alcohol, dip-coating velocity, drying duration in air, thermal treatment and number of cyclical time of the process. Titania nanocrystals were prepared at ambient temperature in a liquid media using titanium tetrabutoxide as precursor, and the crystallization of amorphous precursor was preceded by peptizing with acid and then refluxing for a periodic time in homothermal water-bath. The photocatalytic properties of the La-TiO₂ films had been testified by the photo degradation of methyl orange. The lanthanum-doped anatase TiO₂ thin films were characterized by XRD and TEM. The products show much improved photocatalytic activity that will be useful in the design of a novel antibacterial, deodorant and antipollution new photo reactor.

Abstract: Based on the experimental results from the hot compression tests of homogenized cast AZ61 Mg alloy, processing maps were constructed by superimposition of the instability maps over the power dissipation maps. The domain with the efficiency of power dissipation reaching a local maximum and flow instability region were identified in the processing maps. The processing map obtained at a strain of 0.6 exhibited only one domain with local maximum efficiency of power dissipation. The microstructure observations showed that variation in microstructure was related to the deformation condition, which was associated with the variation in efficiency of power dissipation.

Abstract: Physisorption of hydrogen molecules in metal-organic frameworks (MOFs) provides a promising way for hydrogen storage, in which the van der Waals (vdW) interaction plays an important role but cannot be described by the density functional theory (DFT). Using the vdW density functional (vdW-DF) method, we perform ab initio calculations for the MOF-5 crystal with one or multiple H₂ adsorbed in its primitive cell. It is found that the binding with the organic linker is much smaller than with the metal oxide corner, which limits the H₂ loading. We show that this can be improved significantly (from 5.50 to 10.39 kJ/mol) by replacing the H atoms of the organic linker with F atoms which causes extra electrostatic interaction.

Abstract: Fabrication of ultra shallow junctions with low contact resistances is desired to advance current CMOS technology. The low Boron activation on Group V for ultra shallow junction formation will makes the chip fabrication works effectively. SilvacoTCAD (Technology Computer Aided Design) manages simulation tasks and analyzing simulation results when ultra-shallow junction formation is using low-boron activation on Phosphorus, Antimony and Arsenic.A stimulate process like implantation, diffusion and dopant activation and epitaxial growth in different semiconductor materials has been analyzed as well as investigate the effects of energy of boron ion beams on ultra shallow junction formation.As a result, the electrical characteristics of NMOS structure by obtaining graph of I_D V_GS and I_D V_DShas been studied when there are variations in junction length (X_j), and gatelength (L_g).

Abstract: Technical practice uses a lot of cutting tools made of different materials. According to selecting workpiece have to be defined technological conditions. For all selected technological conditions is important prescribe parameters for machining. The basic parameters for every cutting process are cutting speed, feed and cutting depth. These technological conditions are defined by means of calculation or by means of mechanical engineering tables. Specification of tool wear by means of calculation is very difficult. Very important cutting tool property is its durability. Durability of cutting tool defines lifetime of this cutting tool and it determines its suitability for select technological operation. Technical science defines a lot of different factors, that they may be cause of shorter cutting tool lifetime. For increase cutting tool durability is necessary maximally possible elimination of these factors. Determination of cutting tool durability is very important, because provides comprehensive information how to determine appropriate technological conditions for selected cutting tool. In engineering is for determination of cutting tools durability used T-v_c dependence. The article describes process how to create the durability dependence for cutting tool made of cutting ceramic (Al₂O₃) by means of T-v_c dependence in machining process of C45.

Abstract: The theory and practice in engineering industry is not the same. Wise people say that practice is the only well-mastered theory. The most important part of new discovery is successfully realized experiment. Every experiment has inputs and outputs. Inputs are defined before experiment and they are accurately determined and described. Outputs have to be measured and described after experiment. It is very difficult to describe and express parameters that are base of experiments. Tested parameters and theirs dependencies are very often described by means of graphs, tables or definitions. Lot of parameters and their dependencies in engineering practice are not described by means of formula. Very important and often used standard ISO in engineering practice is standard ISO 3685. This standard includes characteristics for various cutting materials. The main part of this standard is T-v_c dependence for cutting materials. One of the cutting materials contained in standard ISO 3685 is sintered carbide. There are instructions obtained in standard ISO 3685 for creation of T-v_c dependence. The article describes differences between T-v_c dependence for sintered carbide and standard ISO 3685.

Abstract: The welding spot of Ultra-high strength steel of 22MnB5 and common steel of St16 were the investigative objects, the intermediate frequency inverter & electric servo welding system was used to weld the sheets. Electrical measuring test method was used on spot-welded joint under tensile-shear load to determinate the strain of different positions, including the strain of weld nugget, the stain around the nugget and the base metals strain near the weld nugget. The deformation regularity of spot welding joints surrounding and base metal were analysed according to the data. The test provided a reference for the numerical simulation of spot welding model. Test results show that the strain distribution on spot welding joint is not uniform, the strain of the weld nugget center is relatively small, large deformation exists mainly in the heat affected zone. That is to say, the area near the spot-welding joint heat affected zone is prone to yield. The base metal area near the weld nugget is mainly affected by tensile strain, and the strain increases with the increasing of the load. The force condition of the specimen is complicated around the nugget, the relationship between the load and the strain is erratic. The strain of the weld nugget will gradually change from axial compressive strain to axial tensile strain. The strain of spot welding specimen made of dissimilar materials (22MnB5& ST16) is negative, and almost linearly.