Applied Mechanics and Materials Vols. 313-314

Abstract: A new intercalation of Indium and zinc phthalocyanine(ZnPc) thin film is developed by using thermal co-evaporation technique. The exciton dissociation at the interface of Indium Tin Oxide(ITO) electrode and Indium doped ZnPc upon laser irradiation is observed through the transient photovoltage measurement technique in comparison with the interfacial exciton dissociation occurred at ITO/pristine ZnPc interface. The occurring transient photovoltage spike is regarded as the effect of exciton dissociation at ITO/In-doped ZnPc interface and depends on the amount of free carrier separation by built-in field or charge carrier concentration according to doping ratio. The experiments demonstrate the existence of exciton dissociation at ITO/In-doped ZnPc interface, the direction of charges transfer is that holes are injected to ITO, whereas electrons are left in bulk film. A thin insulating layer of 6 nm thick lithium fluoride(LiF) is inserted between ITO and In-doped ZnPc to prevent the exciton dissociation at ITO/In-doped ZnPc interface and insist on the phenomenon of interfacial exciton dissociation. Further photoelectron spectroscopy experiments prove that In-doped ZnPc is hole transport material.

Abstract: A new intercalation of indium and nickel phthalocyanine(NiPc) thin films is developed by using thermal co-evaporation technique. X-ray diffractometer(XRD) and optical absorption spectroscopy of In-doped NiPc suggest the crystal structure of In-doped NiPc is α-phase as same as that of pristine NiPc. Current-voltage characteristic of Shottky diode fabricated with In-doped NiPc thin film shows the enhancement of charge carrier concentration due to indium doping. Further photoelectron spectroscopy experiments prove that In-doped NiPc is hole transport material.

Abstract: Spring back in the process of sheet metal forming leads to deviations between design sizes and actual dimensions of stamping parts, to meet the precision requirements of deviations, the shape of die surface needs to be compensated in the opposite direction according to the predicted spring back by numerical simulation. In this article, the R S coordinate mapping method is used to revise coordinates of finite element nodes according to the predicted spring back, and the bi-cubic B spline surface interpolation method is applied to reconstruct die surface with CAD data format. An example shows that the algorithms are feasible and have some practical values.

Abstract: Emergenceof innovative technological deposition technique of spray pyrolysis enabled the enhancement of structural, optical, and electrical properties of Sn1-xCrxO2 (x=0.0, 0.02, 0.04, 0.06, 0.10, 0.15) transparent semiconductors thin films in the present study. To evaluate these properties, X-Ray diffraction (XRD) spectroscopy were usedto study the elemental component and the crystalline nature of the materials while the optical properties and structure of the samples were evaluated using UV—vis spectroscopy and field emission scanning electron microscopy (FE-SEM).Finding showed that the Cr-doped SnO2 films were tetragonal in shape. Transmission spectra of the deposited films showed high transparency of ~ 70-90% in visible region with optical edge of 3.7eVfor SnO2. Resistivity of pure tin oxide samples was 0.01 Ω-Cm and increases with increase in dopant level. The Hall voltage showed that the type of semiconductor changed with increasing of dopant.

Abstract: This paper presents the development of a nano geopolymer for sustainable concrete using fly ash synthesized by high-energy ball milling. In this paper, we report on our investigation of the effects of grinding on the binder properties and the optimization of the mix design for nano geopolymer paste. The research methodology consisted of synthesizing fly ash by using a high-energy ball mill to create nanosized particles and determining the formulation and mix proportions required to produce a nano geopolymer paste with the addition of an alkaline activator. The ratio of fly ash to alkaline activator and sodium silicate to sodium hydroxide were constant for the entire experiment which is 2.5. Ball milling was conducted for the total duration of six hours, during which particle size was reduced from 10 μm to 60 nm. The nano geopolymer were cured at temperature 70°C and then tested on 1st day and 7th day for compressive strength. Scanning electron microscopy (SEM) was used to characterize the shape, texture, and size of the milled fly ash.

Abstract: The development of asbestos free brake pad composites using different fillers was investigated with a intention to substitute asbestos which is known hazardous and carcinogenic. Mechanical and morphology studies were made to clarify the mechanism for compressive strength, hardness and wear rate behavior of different filler of brake pad which were prepared by compression molding of mixture of filler (palm slag, calcium carbonate and dolomite) with phenolic as binder, metal fiber as reinforcement, graphite as lubricant and alumina as abrasive. The result showed that palm slag has significant potential to use as filler material in brake pad composite. The wear rate of palm slag composite was comparable with the conventional asbestos based brake pad. The result also supported by SEM micrograph.

Abstract: Melt flow and casting solidification are essential parts of the permanent mold casting process and affect significantly the quality of castings．For this reason, accurate prediction of mold filling pattern and temperature field in permanent mold castings plays on an important role in producing sound castings. In this paper, the model filling and solidification of a box casting produced from an aluminum alloy is studied. Different casting processes are employed, simulated and optimized to obtain sound castings. Simulation results reveal that with appropriate gating system, pouring rate, cooling line, a smooth mold filling, reduced shrinkages and other defects are available and desired sound castings can be produced.

Abstract: Diluted magnetic semiconductor Zn_1-xMn_xO crystals were synthesized at 430°C for 24h by hydrothermal method. 3mol·L^-1KOH was used as the mineralizer, and the fill factor is 35%. The obtained crystals show a ZnO wurtzite structure, with positive polar faces{0001}, negative polar faces{000 }, p faces{ 011} and –p faces { 01 } exposed. The height of the crystal is 5-30 m and radius-height ratio is2:1. Mn atom concentration of 2. 6% (x=0.026) was determined using X-ray energy dispersive spectroscopy ( EDS). The crystals show low-temperature ferromagnetism with Curie temperature of 50K.

Abstract: The friction and wear characteristics of PES/metal matrix composite materials were tested by the ball-disc friction pair of UMT-2 friction and wear test machine. The plastic layer is composed of distinct components. The results showed that: the tribological properties of PES/metal matrix composites were improved significantly after added 5wt % of the LCP. With the increasing of PTFE the PES/metal matrix composite material friction coefficient and wear rate were decreasing when the load of 10N and rotating speed of 400rmp. But the friction coefficient and wear rate increased when the mass fraction of PTFE more than 22 wt %. The tribological properties were the best when the PTFE content was 18 wt % to 25 wt % in the plastic layer.

Abstract: In this paper , the ZnO crystal was synthesized using hydrothermal method through 24 hours^' reaction with 35 % filling factor at 430°C. When the mineralizer concentration is rather low (eg. lmol/L NaOH), only ZnO microcrystal is produced. The mineralizer concentration increases, the larger crystal was present. When 5 mol·L^-1 NaOH served as mineralizer, the extent of the synthesized crystal was nearly 500μm. The ZnO cryslals with length of 1500μm were present when 3ml·L^-1 KOH served as mineralizer. Respectively when 3mol·L^-1 NaOH and lmol·L^-1 KBr were used as mineralizer, the extent of the synthesized crystal was nearly 700μm , the diameter was 200μm and the exposed faces m { 100} , p { 101 } was complete , so we obtained the higher quality crystals. Besides the larger crystal, a great deal of microcrystal and nanocrystallites cluster was also present in the product.