bluuebunny/crossref_metadata_2025 huggingface dataset:
Researches of a Novel 2D CMOS Thermal Based Accelerometer
Authors: Shen Chih Hsiung , Chen Shu Jung , Yang Yin Ting
Published: March 2009

Conventionally the accelerometer behaves like a spring – mass system and its structures
involve solid proof mass, which is allowed to move under acceleration conditions. In this paper, we
design and fabrication a novel thermal-bubble-based micromachined accelerometer with advantages
of minimum solid thermal conductance and high sensitivity successfully. The proposed accelerometer
based on thermal convection creates a tiny heated air bubble hermetically sealed inside the sensor
package cavity. Four thermopiles around the center heater serve as the temperature sensors to detect
two-dimension motion of the chip and also are adequately applied to the technology of inclinometers,
anemometers and flow meters. A new micro-link structure is also proposed to enhance the
construction of accelerometer with the micro heater and two pairs of thermopiles floating over an
etched cavity. The heater and the thermopiles are connected by network-like structure of micro-links,
which enhance the structure and greatly reduce the solid heat flow from the heater to the hot junctions
of thermopiles. The samples are fabricated by TSMC 0.35μm 2P4M CMOS process which is
provided by CIC with outstanding strong structures and uniform quality. Our design is proved to be
adequate for commercial batch production. We measure the output signal by inclining the sensor to
evaluate the performance of this accelerometer.
Oxidation Performance of High Temperature Mo-Si-B Alloys and Coatings
Authors: Perepezko John H. , Rioult F. , Sakidja R.
Published: March 2009

Mo-Si-B alloys are attractive due to their high temperature mechanical properties and
high melting temperature. The oxidation of multiphase alloys develops in two distinct stages. First,
there is a transient stage that corresponds to the evaporation of the volatile MoO3 and to an initial
high recession rate. The steady state stage of the oxidation begins when the slower forming
borosilicate layer becomes continuous and inhibits further rapid oxidation. Then, the oxidation rate
is limited by oxygen diffusion through the borosilicate layer. In order to inhibit the transient stage, a
coating strategy has been developed to capitalize on the interdiffusion reactions and to employ a
kinetic bias to modify interface reaction products in order to maximize the high temperature
stability and performance. In order to achieve a compatible interface coating together with enhanced
oxidation resistance, a pack cementation process has been adopted to synthesize metal-rich silicide
and borosilicide surface layers. The analysis of the enhanced oxidation performance indicates that a
strategy based upon the operating principles of interface reactions in multicomponent systems is
effective for developing stable and robust coating systems.
Phase Field Modeling of Interdiffusion Microstructure in Ni-Cr-Al Diffusion Couples
Authors: Mohanty R.R. , Sohn Yong Ho
Published: March 2009

Evolution of interdiffusion microstructures was examined in ternary Ni-Cr-Al solid-tosolid
diffusion couples using two-dimensional (2D) phase field simulation. Utilizing Cahn-Hilliard
and Allen-Cahn equations, multiphase diffusion couples containing of fcc-γ and B2-β solid solution
phases were simulated with alloys of different compositions and phase contents. Chemical mobility
as a function of composition with constant gradient energy coefficients was used in the simulation.
Simulated microstructures in γ+β/γ and γ+β/γ+β diffusion couples were compared with the
experimental microstructures reported in literature. As observed experimentally, the model
predicted the recession of γ+β region in the γ+β/γ couple and a stationary interface in γ+β/γ+β
couple. Concentration profiles developed across the diffusion couples demonstrated that the
interdiffusion occurs in the γ phase as well as in the γ+β region. Formation of single-phase γ and β
layers near the interface of γ+β/γ+β couples was also investigated using the volume fraction profile
obtained from the simulated microstructure.
Steam Oxidation of Advanced Steam Turbine Alloys
Authors: Holcomb Gordon R.
Published: March 2009

Power generation from coal using ultra supercritical steam results in improved fuel
efficiency and decreased greenhouse gas emissions. Results of ongoing research into the oxidation
of candidate nickel-base alloys for ultra supercritical steam turbines are presented. Exposure
conditions range from moist air at atmospheric pressure (650°C to 800°C) to steam at 34.5 MPa
(650°C to 760°C). Parabolic scale growth coupled with internal oxidation and reactive evaporation
of chromia are the primary corrosion mechanisms.
Alkali Induced Corrosion of 304-Type Austenitic Stainless Steel at 600°C; Comparison between KCl, K2CO3 and K2SO4
Authors: Pettersson J. , Svensson Jan Erik , Johansson Lars Gunnar
Published: March 2009

The influence of KCl, K2CO3 and K2SO4 on the initial stages of corrosion of 304-type
(Fe18Cr10Ni) stainless steel was investigated at 600°C in 5% O2 + 40% H2O. Small amounts of
salt (1.35 .mol K+/cm2) were added before exposure. The exposures were carried out in a
thermobalance. Exposure time was 24 hours. Reference exposures were carried out in 5% O2 and
in 5% O2 + 40% H2O. The oxidized samples were analyzed by SEM/EDX, XRD and IC. KCl and
K2CO3 are very corrosive towards 304L, producing thick non-protective scales. Corrosion is
initiated by the reaction of the potassium salts with the protective, chromium-rich oxide forming
K2CrO4. This depletes the oxide in chromia and converts it into iron-rich non-protective oxide. In
contrast, K2SO4 does not accelerate corrosion significantly.
Room Temperature Plastic Flow Localization in a Mn-Alloyed Austenitic Steel
Authors: Firrao Donato , Matteis Paolo , Mortarino Giovanni M.M. , Russo Spena P. , Scavino Giorgio , D'Aiuto F.
Published: March 2009

A fully austenitic steel containing 0.5 wt.% C and 22 wt.% Mn was recently proposed for the fabrication of automotive body structures by room-temperature sheet forming, the goal being weight reduction and better crash performance owing to its much higher yield stress and elongation (as compared to presently employed ferritic and multiphase steels). Full-thickness tensile specimens, cut from as-produced sheets, were polished and tested at different strain rates, and the macroscopic surface relief eventually induced by the plastic deformation was recorded with a video camera. Between 0.3 and 0.4 true strain, successive macroscopic deformation bands (forming about 45° angle with the tensile axis and involving the full specimen width) travel along the specimen, a new one being nucleated as the previous reaches one of the specimen heads, whereas the gage displacement vs. stress curve shows a series of steps, each corresponding to the transit of a band through the gage length, and the cross-head displacement vs. stress curve shows isolated stress peaks, each immediately preceding the nucleation of a new band. Afterwards, and up to rupture, a series of stationary deformation bands appear, most being immediately adjacent to the preceding ones, with the stress vs. strain curve showing a series of serrations with large stress drops. As the strain rate is increased from 0.0004 to 0.4 s-1, the overall flow stress slightly decreases and the mentioned plastic localization phenomena become less evident.
Hot Working of the ZEK200 Magnesium Alloy
Authors: Spigarelli Stefano , El Mehtedi Mohamad , Ricci P.
Published: March 2009

The high temperature workability of the ZEK200 Mg-alloy produced by Direct Chill casting (DC) was investigated by torsion testing between 200 and 450°C. The alloy exhibited a higher strength and a slightly lower equivalent strain to fracture than AZ31 and ZM21 produced by DC. The calculation of the constitutive equation gave a value of the activation energy for high temperature deformation close to 175 kJ/mol, in line with those calculated by following the same procedure in AZ31 and ZM21. Partial or complete recrystallization of the deformed structure was observed at 350 and 400°C respectively. Grain growth occurred after recrystallization in the samples tested at 450°C.
Development of Ultra-Fine Microstructure in Titanium via Powder Metallurgy for Improved Ductility and Strength
Authors: Eylon Daniel , Ernst William A. , Kramer Daniel P.
Published: March 2009

In an effort to produce an ultra-fine alpha titanium equiaxed grain structure, suitable for superplastic deformation processes, Armstrong-Process CP Ti powder, was consolidated into compacts with grain-size on the order of 2 to 3 microns. This powder has very fine dendritic-shaped particles with an inherent sub-micron grain-structure. In order to preserve as much as possible the fine powder microstructural scale, the compaction was accomplished by rapid-heating and short-hold VHP, using a procedure derived from a processing technique originally developed at the University of Dayton for producing nano-phase hard permanent magnets. It was modified to suit the titanium powder, and a range of parameters was experimented to produce a variation of microstructures. One set of compaction conditions resulted in the desired microstructure, and subsequent tensile testing demonstrated strength and ductility exceeding CP Ti Grade 3, due to the ultra-fine equiaxed alpha grain structure. The paper will discuss the various microstructures and the potential applications.
Interpretation of Profile and Intercept Counts in Microstructure Characterization
Authors: Saxl Ivan , Sklenička Václav
Published: March 2009

The results of intercept and profile counts are commonly interpreted as a suitable estimates of the mean grain size as represented e.g. by the grain density V. The term grain size is not explicitly defined even when some relation to grain volume and/or mean grain breadth (the mean Ferret diameter) is tacitly assumed. However, the intercept count L is directly related to the mean value of grain boundary area per unit volume SV and the profile count A is, under relatively general assumptions, directly related to the mean value of grain junctions per unit volume LV. Their relation to V can be generally written as V = c¢(A)3/2 = c²(L)3, but the coefficients c¢ and c² strongly depend on the structural characteristics like grain size dispersion, anisotropy etc. and their evaluation is far from being simple. Consequently, whereas the reliable estimates of SV and LV result from intercept and profile counts, the estimate of grain density based on them requires a careful consideration.
Guiding of a Slow Positron Beam with a Glass Capillary
Authors: Oshima Nagayasu , Iwai Y. , Kojima T.M. , Ikeda Tokihiro , Kanazawa Y. , Hoshino M. , Suzuki Ryoichi , Yamazaki Y.
Published: March 2009

Slow positron beam was injected into a non-tapered glass capillary which was tilted angle of θ from the beam axis by a movable stage. Beam profiles of the positrons transported through the capillary were observed with a phosphor screen combined with micro channel plates as a function of θ. Some fraction of positrons was deflected with the tilting angle of the capillary.
Photovoltaic Power Generation: The Impact of Nano-Materials
Authors: Peaker Anthony R. , Markevich Vladimir P.
Published: March 2009

Solar power is seen by many as a solution to the world’s energy problems. The earth receives 1.7x1017W from the sun compared to a total electricity generation capacity of 4.6x1012W (OECD prediction for 2010). However the average power density is low with a daytime average over the earth of 680Wm-2. This makes centralised generation problematic but distributed photoelectric generation by domestic and commercial users is a rapidly developing market. However typical commercially available modules have an energy conversion efficiency of less than 12%. Silicon cells with 24% efficiency have been produced in the lab while multi-junction tandem cells using different semiconductor materials (GaInAs, GaInP and Ge) to absorb different parts of the sun’s spectrum have reached 40%. This chapter describes some of the materials and device achievements so far and looks at possible ways in which higher efficiencies might be achieved with particular emphasis on nano-materials to use more of the solar spectrum efficiently. The possibility of using quantum slicing and multiple exciton generation to make more efficient use of high energy photons is considered and impurity band generation as a possible route to use low energy photons. One of the greatest challenges is to do this cheaply using semiconductors made from non-toxic abundant elements.
Correlation between Physicochemical and Electrical Properties of Hydrogenated Amorphous Silicon Doped with Boron: Effect of Thermal Annealing
Authors: Seba H.Y. , Cherfi R. , Hamadache Farida , Aoucher M.
Published: March 2009

This communication reports on the effect of thermal annealing on the physicochemical and electrical properties of boron doped amorphous silicon thin films deposited by reactive magnetron sputtering in a mixture of argon and hydrogen atmosphere. The IR absorption spectra of as prepared samples exhibit the peaks characteristic of Si-H, Si-B and B-H bonding vibrations. After annealing, our analyses revealed some modifications in the peak characteristic of B-H bonding, while no significant increase in Si-B peak intensity was observed. In other respects, electrical measurements showed an increase in the conductivity from 10-8 to 10-5 -1 cm-1 and a decrease in its activation energy from 0.57 eV to 0.33 eV after a successive annealing at temperatures varied between 150°C and 450°C. These results showed that boron doping becomes increasingly efficient after annealing, which could be assigned to the reduction in the content of hydrogen playing an important role in the passivation of boron atoms.
Formation of Rough TiO2 Thin Films on Glass and Porous Silicon by Sol-Gel Method
Authors: Benzekkour N. , Ghomrani F.Z. , Gabouze N. , Kermadi S. , Boumaour M. , Ferdjani K.
Published: March 2009

Substrate dipping in a composite sol-gel solution was used to prepare smooth and rough thin films of titanium dioxides (TiO2) on porous silicon (PS) and conductor glass. The fabrication process and optical measurements of these layers are presented. Sol-gel films were coated by dip-coating method on porous silicon layer. The characterizations of deposited layer were performed by spectral response, ellipsometry and spectrophotometry.
The results show that the optical and electrical properties of the structures strongly depend on the deposition conditions of TiO2.
In addition, the band gap energy Eg and refractive index of the structure can be easily varied depending on TiO2 thicknesses and calcination temperatures.
Finally, the electrical and optical parameters show a promising result in solar cells application and photocatalytic activity.
Characterization of Thin Layer SnO2/Glass by Neutrons Reflectometry
Authors: Khelladi Mohamed Fadel , Izerrouken M. , Kermadi S. , Tala-Ighil R. , Sali Samira , Boumaour M.
Published: March 2009

The thermal annealing behavior of the SnO2 thin films elaborated by sol-gel method has been studied by the neutrons reflectivity technique. From the fit of the experimental data using Parratt32 software program developed at HMI, Berlin, scattering length density, thickness and roughness are extracted. The obtained results show that the film thickness increases with the increasing annealing temperature, and the roughness is higher at 500 °C. Whereas, approximately, the same scattering length density is obtained after each annealing temperature.
Electrical and Optical Behavior of Al2O3/Porous Silicon/Silicon Structures
Authors: Gabouze N. , Ait-Hamouda Kahina
Published: March 2009

In this paper, a promising class of optical filters is introduced, based on Al2O3/PS/Si structure. The filters consist of thin layer of aluminium electrochemically oxidized in different aqueous solution, on porous silicon. The spectral sensitivity can be easily varied by Al2O3 thickness. This result is a consequence of refractive index variation of Al2O3 and PS layers, confirmed by ellipsometry measurements.
Functionality of Ti-O Thin Films Doped by Phosphorus: Wettability, Semiconductor Performance and Blood Compatibility
Authors: Wang Jin Biao , Yang Ping , Li Gui Cai , Yang Zhong Hai , Leng Yong Xiang , Sun Hong , Huang Nan
Published: March 2009

For an application as biomedical materials of high performance with a good biocompatibility, the Ti-O film on Si (110) wafer substrate has been synthesize by means of unbalance reactive magnetron sputtering method and modified by phosphorus ion implantation and succeeding vacuum annealing. X-ray diffraction (XRD) results indicated that such prepared Ti-O film had a rutile structure. X-ray photoelectron spectroscopy (XPS) analysis demonstrates the effect of P ion doping. The contact angle test and sheet resistance results showed that titanium oxide film and phosphorus-doped titanium oxide film became more hydrophilic and higher conductance after annealing. The morphology and roughness of the surface have been investigated using SEM. Antithrombotic property of the titanium oxide thin film was examined by platelet adhesion tests. The results showed that the undoped Ti-O films and the P implant and annealing at 900 °C Ti-O film had good blood compatibility.
Neovascularization of Porous Silk Fibroin Films(PSFFs) as Dermis Substitutes Implanted in Rats
Authors: Guan Guo Ping , Bai Lun , Zuo Bao Qi , Li Ming Zhong , Sun Zi Lin , Wu Zheng Yu
Published: March 2009

Neovascularization in biomaterials plays a key role in wound healing. In this paper, porous silk fibroin films (PSFFs) whose structure was optimized, as dermis substitutes, were implanted in the back skin of rats for recovery of dermis loss. Results showed that a thin layer of loose connective tissue had formed at the interface between PSFFs and subcutaneous tissues, in which abundant blood vessels could be observed at 24 h after surgery. Whereafter the newly formed connective tissue thickened and the number of microvessels in the tissue increased. Furthermore, a few microvessels could be seen in PSFFs at day 5, most of which were capillaries. By day 10, the density of microvessels in PSFFs increased to a peak while the percentage of capillary decreased. At day 23, both the density of microvessels and the percentage of capillary was almost equal to those of normal tissues. In summary, wound healing with PSFFs as dermis substitutes is the neovascularization process of PSFFs. The process includes three major steps: (1) new formation and growth of loose connective tissue into the pores of PSFFs, (2) proliferation and migration of fibroblasts and endothelial cells, and (3) formation of functional microvessels and their networks.
Influence of the Flux Ratio N2/Ar on the Formation of Mo-N Modification Layers on Ti6Al4V by Plasma Reactive Sputtering
Authors: Li Xiu Yan , Zhang Ying , Tang Bin , Xu Zhong
Published: March 2009

Ti6Al4V alloy is promising biology material with outstanding properties of low density, high specific strength, and exceptional corrosion resistance. However, one of its disadvantages is the poor tribological property. In this paper Mo-N hard surface modification layers were formed on Ti6Al4V at 900°C substrate temperature by plasma reactive sputtering. The flux ratio N2/Ar is an important parameter and its influence on the composition, structure and hardness of the Mo-N layers is studied. The Mo-N layers are duplex layers, composed of diffusing layer and surface coating. The component of Mo and N elements in the diffusing layer changes gradually which can enhance the load-bearing capacity to the coating and ensure the durability of the coating. With the increase of the flux ratio N2/Ar, the content of N element in the Mo-N layers increases. The Mo-N layers were polycrystalline γ- Mo2N with (200) plane oriented parallel to the substrate surface. The surface hardness of the formed layers is in the range HK1330-1430. The hardness of the Mo-N layers increases with the increase of the flux ratio N2/Ar and the reason is that the content of N element in the Mo-N layers increases.
Study on the Preparation and Micro Structure of the Mg Containing Porous HA with Ultra-Fine Grain
Authors: Li Xing Yi , Meng Xiang Cai , Liu Guo Quan , Yuan Shi Dan
Published: March 2009

The Nano-HA powder were synthesized by chemical precipitation with Ca(H2PO4)2•H2O and Ca (OH)2 and porous HA was prepared by sintering with magnesium as pore-creator. Nano-HA powder and porous HA were characterized by wide angle X-ray diffraction, transmission electron microscopy(TEM), scanning electron microscopy (SEM), SEM in combination with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy. The experimental results show that HA powder synthesized by chemical precipitation is nanometer powder. Magnesium was ideal pore-creator for preparation of porous materials. The grain size of porous HA was sub-micron and MgO which existed in the grain boundary of HA as a second phase particles that played the roles of inhibiting the HA grain growth.
Preparation and Characteristics of Gradient Silk Fibroin/Hydroxyapatite Porous Composites
Authors: Xu Wei Wei , Liu Jian Bing , Li Ming Zhong , Lu Shen Zhou , Luo Miao Liang
Published: March 2009

The gradient silk fibroin (SF)/ hydroxyapatite (HA) porous composite used for the scaffold of cartilage-bone tissue regeneration was prepared with SF powder and HA powder by layer-by-layer mould pressing method and granular NaCl as porogent. The characteristics were performed by Electron Microprobe and Energy Dispersive Spectometer (EDS). It indicated that the distribution of SF and HA presented linear gradient along the thickness direction in the materials. The porosity of composites increased with NaCl content increasing, while the density decreased. As the result of mechanical properties measurement, the bending strength and compressive strength decreased with NaCl content increasing. Compared the mechanical properties between gradient material and non-gradient material, it indicated that bending strength of gradient SF/HA porous material was higher than non-gradient SF/HA porous material’s.
Effect of Si Content on the Synthesis of Ti3SiC2 Bulk Material by Pressureless Sintering
Authors: Kuang Ying Huan , Ngai Tungwai Leo , Hu Chang Xu , Li Yuan Yuan
Published: March 2009

Ti3SiC2 is a bioinert material. The combination of high fracture toughness, excellent corrosion resistance and easy machinability make it a new class of potential biomaterials for orthopedic applications, dental implants, and fixation devices for the bone. In this paper, effect of Si concentration on the sintering of Ti3SiC2 bulk material was reported. Ti3SiC2 bulks were fabricated by pressureless reactive sintering of powder compacts made of Ti, Si and graphite powders. Nearly pure Ti3SiC2 bulk was obtained by reactive sintering of the powder compact, with a nominal composition of 3:1.1:2 in molar ratio of Ti:Si:C, at 1500 °C for 120 minutes. TiC, a non-preferable impurity was avoided by the appropriate addition of excess Si (relative to stoichiometric composition of 3:1:2 in Ti3SiC2). However, too much Si will result in the formation of significant amount of TiSi2 and SiC in the sintered Ti3SiC2. Microstructure of the prepared Ti3SiC2 bulks was analyzed by scanning electron microscope. Phase constituent analysis was carried out by x-ray diffraction. Effect of Si content on the density of sintered samples was also studied.
Surface Hydrophilicity Improvement of RGP Contact Lens Material by Oxygen Plasma Treatment
Authors: Yin Shi Heng , Wang Ying Jun , Ren Li , Zhao Lian Na , Chen Hao , Qu Jia
Published: March 2009

Oxygen plasma was employed to treat a fluorosilicone acrylate RGP contact lens material (Boston EO) in order to improve surface hydrophilicity. X-ray photoelectron spectroscopy (XPS) was applied to characterize the surface chemical state. The surface morphology and hydrophilicity were investigated by scanning electron microscope (SEM) and contact angle measurement respectively. The surface contact angle measurement indicated an evident improvement of surface hydrophilicity after plasma treatment. XPS results indicated that the incorporation of oxygen and the transform of -Si-CH3 into hydrophilic -Si-O after plasma treatment were the main reasons for surface hydrophilicity improvement. SEM showed some decrease of surface roughness under moderate plasma condition. But plasma with higher power would etch the material surface.
Surface Modification of Fluorosilicone Acrylate RGP Contact Lens by Low-Temperature Ammonia Plasma
Authors: Ren Li , Zhao Lian Na , Yin Shi Heng , Wang Ying Jun , Chen Hao , Qu Jia
Published: March 2009

In order to improve the surface hydrophilicity and the resistance to protein deposition of fluorosilicone acrylate RGP (rigid gas permeable) contact lens, low temperature ammonia plasma treatment was used to modify the lens surface. The changes of surface structures and properties were characterized by contact angle analyzer, X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). Effects of exposure time and plasma generating power on surface properties of the RGP contact lens were investigated. The surface contact angle measurements showed a great improvement of hydrophilicity after plasma treatment. XPS analysis indicated that the oxygen content and the nitrogen content increased remarkably after ammonia plasma treatment. Furthermore, the content of the hydrophilic group O-C=O/N-C=O on the surface increased and the content of the hydrophobic group CF2 decreased after plasma treatment. AFM results showed that ammonia plasma could lead to surface etching.
The Targeting Magnetic Induction Heating of Nano-Carbon Iron Composite
Authors: Chen Jin , Zhang Hai Yan , Li Li Ping
Published: March 2009

A nano-carbon and iron composite--carbon coated iron nanoparticles produced by carbon arc method can be used as a new kind of magnetic targeting and heating drug carrier for cancer therapy. It presents an special nanostructure of iron nanoparticles in inner core and nano-carbon shells outside. The nano-carbon shells have a high drug adsorption ability because of its high surface area and its inner core has great effect of targeting magnetic heating. Magnetic induction heating effect of pig liver injected mixed liquids with different concentration carbon coated iron particles in physiological saline indicates that the more quantity of nanoparticles used, the higher temperature it is. Magnetic induction heating effect of the pig liver was compared in the case of filling method and injection method (both were containing 0.3g carbon coated iron nanoparticles). The iron nanoparticle in its inner core has good effect of magnetic induction heating, the temperature can go up to 51 °C in the case that carbon coated iron nanoparticles mixed with physiological saline were distributed uniformly in pig liver. And the temperature can go up to 46°C in the case that carbon-coated iron nanoparticles was injected in a certain section of pig liver. It is obvious that injected one is much better than that of filled, but they are all enough to kill the cancer cells.
Adhesion Strength of Sol-Gel Derived FHA Coating on Laser Gas Nitrided Pure Ti
Authors: Wang San Jun , Yang Sen , Wang Ming Run
Published: March 2009

Fluor-hydroxyapatite (FHA) films were deposited on titanium and laser gas nitrided titanium substrates using sol-gel technique respectively. Typical apatite structures were obtained for all coatings after dipping and subsequent heat treatment from 600°C to 800°C. The obtained films were uniform and dense, with a thickness of 5 μm. The 3-D TiN dendritic structure fabricated on the surface of Ti plate using laser gas nitriding technique in advance should be help anchor the HA/FHA coating and improved the interfacial adherence significantly compared with the naked titanium surface.
The Segregation of Chemical Composition in NiTi Shape Memory Alloy Melted by VIM in Lime Crucible
Authors: Yuan Zhi Shan , Feng Zhao Wei , Wang Jiang Bo , Miao Wei Dong , Li Chong Jian , Liu Wei
Published: March 2009

Binary NiTi shape memory alloy cast ingots with large scale size are produced by using vacuum induction melting (VIM) in lime crucible, the oxygen and carbon contents are less than 500ppm. Usually, oxygen was introduced into the melts by the dissolution of lime during melting, resulting in higher content of oxygen over 500ppm. VAR + VIM ingot metallurgy is prone to produce materials with a good chemical homogeneity. However, it is difficult for one single melting of NiTi by VIM in the lime crucible. So in the present paper, the segregation of chemical composition and the consistency of transformation temperature in NiTi alloys in as-casted condition along the cross-section area on edge and center, in homogeneization-treated condition, and in as-forged condition along the longitudinal-section area on head and tail, are measured and analyzed by differential scanning calorimetry (DSC), OM, SEM, and XRD, to indicate the chemical homogeneity in microscopic and macroscopic scale.
A Ni/Surface-Modified Diamond Composite Electroplating Coating on Superelastic NiTi Alloy as Potential Dental Bur Design
Authors: Zhou Hui Min , Li Qing Fen , Li Li , Zheng Yu Feng
Published: March 2009

Dental diamond bur is now a regular rotary tool, with its head made of diamond particles embedded into nickel coating, and its shank made of stainless steel. There are strong demands from the dentist on prolongation of usage life and avoiding of breakage. To solve this problem, on the one hand, since diamond is hard to be wetted under the condition of normal temperature and pressure due to the high interfacial energy between diamond and general metals and alloys. Diamond particles coated with titanium layer was used for the preparation of composite electroplating with the intention of improving the interfacial adhesion between diamond and metal matrix; on the other hand, superelastic biomedical NiTi alloy was used as the substrate to improve the flexibility and prevent the breakage. In this study, the optimal preparation parameters of Ni/surface-modified diamond electroplating were determined by orthogonal test, and the bonding conditions between the diamond particles and the NiTi alloy substrate were studied by scanning electron microscope. Further performance comparison of Ni/modified and Ni/un-modified diamond composite electroplating was conducted on a pin-on-disc wear machine under the dry sliding condition, and the material removal volume was used as the evaluating criterion of wear resistance. The results showed that the binding strength between diamond particles and NiTi alloy substrate could be enhanced, as well as the wear resistance, which may give direction on the future design of dental bur.
Microstructure and Shape Memory Properties of Biomedical Ti-(40-65) Ta (wt. %) Alloys
Authors: Ma Yun Qing , Jin Wan Jun , Yang Shui Yuan , Zhang Jin Bin , Huang Yi Xiong , Liu Xing Jun
Published: March 2009

Recently Ni-free Ti-based shape memory alloys have been actively studied for biomedical applications in order to replace Ti-Ni alloys which bear the possibility of Ni-hypersensitivity. In this paper, The Ti-(40-65) Ta (wt. %) alloys have been studied with regard to their microstructure, mechanical and shape memory properties, as well as the effect of heat treatment on their shape memory behaviors. The results show that Ti-40wt. %Ta exhibits single orthorhombic structure (''), Ti-55wt. %Ta mainly '' and a little BCC structure (β), and Ti-65wt. % Ta mainly β and a little '' at room temperature. The tensile strengths of Ti-Ta alloys are all over 550 MPa, and the elongations over 17%. The Young’s modulus of Ti-Ta alloys ranges from 66 to 75 GPa, which are closer to the modulus of human bone as compared with that of Ti-6Al-4V alloy. The maximal shape memory strain of 3.32% was obtained in Ti-55wt. %Ta alloy quenched at 1273 K followed by aging at 723 K for 10min. The obtained results will be beneficial for developing Ti-Ta alloys for biomedical applications.
Study on the High Performance Coal Gangue Foam Concrete
Authors: Yu Xin Gang , Wang Hong Fei , Li Yue Xiang , Gong Yi , Li De Jun , Ye Jian Xiong , Shu Dong , Wei Ming
Published: March 2009

The high performance coal gangue foam concrete with the dry density less than 440kg/m3, the thermal conductivity less than 0.085W/(m•K) and the compressive strength over 2.0 MPa was prepared. The microstructure of the coal gangue foam concrete was analyzed by SEM. The hydrates of the coal gangue foam concrete were detected by XRD, and the temperature stability of the coal gangue foam concrete was analyzed by DTA and DSC.
Photocatalytic Degradation of Organic Dye on Sulfated Nanosize TiO2 Sensitized by H2O2 under Visible irradiation
Authors: Zou Jian , Gao Jia Cheng , Wang Yong
Published: March 2009

Nano-TiO2 synthesized by hydrolysis of TiCl4 demonstrated high reactivity in presence of peroxide hydrogen under visible light (λ>420nm).The nano-TiO2 powders were characterized by XRD, Uv-Vis, FT-IR. The results showed that the TiO2 nanocatalyst sensitized with peroxide hydrogen could absorb visible light up to 550nm, and Vis absorption could be extended to 600 nm for the sulfated TiO2 .Photocatylytic degradations of methyl orange and methylene blue were above 90% for sulfated TiO2 in 180min. The inorganic sulfate species absorbing on the surface of titania were mainly responsible for the high activity of the TiO2 under visible light regions．
Study of High Co Superhard High Speed Steel Surface
Authors: Li Zhong Hou , Liu Sha Sha , Cheng Zhi Yong
Published: March 2009

Cobalt- superhard high speed steel layer has been formed on the surface of low alloy steel 20Cr2V by tungsten-molybdenum-cobalt plasma surface alloying and following plasma carbonizing. After plasma surface alloying, a homogeneous and dense surface alloying layer was formed, thickness of which is 200μm. Composition, microstructure and properties of the alloying layer were investigated. Contents of W, Mo, Co, Cr, V and C in the surface layer reach 8%,5%, 6% ,4%,1.5% and 1.5% or so respectively. The concentrations of alloy elements basically meet the requirements of high cobalt type superhard high speed steel. Constituent phases of the surface layer were martensite, M7C3 ,M2C and Cr3C2 carbides and μ phase after quenching treatment. The advanced gradient superhard high speed steel possesses not only high surface hardness, high anti-temper softening ability but also enough toughness.
Photocatalytic Activity of TiO2-C Composites under the Visible Light
Authors: Li Jin Huo , Zhu De Gui , Xue Zong Yue , Guo Shuang Quan
Published: March 2009

TiO2-C composites of high photocatalytic activity were in-situ fabricated with nano-TiO2 powders and resins. The composites were characterized by differential scanning calorimetry and thermal gravimetric analysis (DSC-TG), X-ray diffraction (XRD), UV-Vis diffuse reflection spectrum (DRS), transmission electron microscope (TEM) and scan electronic microscopy (SEM). XRD results indicated that the composites consist of carbon and anatase phases. UV-Vis DRS showed that composites not only have a good performance in the ultraviolet region, but also have a very good performance in the visible light region. Photocatalysis degradations of methyl orange with purity nano-TiO2 and TiO2-C composite were tested by lighting of visible light. After methyl orange liquid was lighted by visible light for 1 hour, the decolorization ratio of methyl orange can be up to 96.3%( reactive brilliant red X-3B:98.7%) with TiO2-C powders, while it was only 34.7% (reactive brilliant red X-3B:66.9%) with purity nano-TiO2 powders. In-situ fabricated carbon can change the width of energy band of TiO2 and adsorb methyl orange and reactive brilliant red X-3B molecules. The former accelerate the absorption of visible light, and the later raise the decomposition rate of methyl orange and reactive brilliant red X-3B. All of these can improve photocatalytic activity of TiO2-C composites under the visible light.
Experimental Study on Solar Photovoltaic System with Compound Parabolic Concentrator
Authors: Yang Dang Qiang , Yang Chang Min , Yuan Jin She
Published: March 2009

The photovoltaic system with compound parabolic concentrator was designed and fabricated based on the performance of polycrystalline-silicon solar cells with back surface field structure. The performance of the system was investigated on site. The experimental results showed that the effective concentration ratio is to be 2.5 and the output power of the system can be increased approximately by 2 times compared to that of the flat plate system. The prototype modules with CPC can provide a potential possibility in power production application, and can reduce the cost of photovoltaic electricity.
Antibacterial Behavior of Ag-Ce-TiO2 Composite Films in the Different Irradiations
Authors: Zhang Tie , Zhu Dong Bin , Wang Chun Guang , He Xin
Published: March 2009

An Ag-Ce-TiO2 composite film was prepared by incorporating Ag in the Ce-TiO2 films with an impregnation method through photoreduction. The bactericidal activity of the Ag-Ce-TiO2 composite film and the effect of deposition of silver and doping cerium in the different irradiations on the antibacterial performance were assessed against Escherichia coli (E. coli). TIhrough characterization of X-ray diffraction (XRD), X-ray photoelectronic spectra (XPS) and UV/VIS diffusive reflectance spectra (DRS), it was found that the Ag-Ce-TiO2 composite film was composed of predominant anatase titania, cerium oxides (in the form of Ce2O3/CeO2) and silver nanoparticles. Moreover, the bactericidal activity of the Ag-Ce-TiO2 composite film and the effect of deposition of silver and doping cerium in the different irradiations on the antibacterial performance were assessed against Escherichia coli (E. coli). The results show that the Ag-Ce-TiO2 composite film has much higher antibacterial efficiency than that of glass and pure TiO2 film either in the room light or in the dark. Therefore, this composite film is promising in applications of antimicrobial and self-clean technologies.
Investigation on Wear- and Corrosion Resistance of TiN Films by CVD
Authors: Wang Chao , Zhou Chungen
Published: March 2009

TiN films have been deposited on K211 super alloy substrates by chemical vapor deposition (CVD) using a gaseous mixture of TiCl4, NH3, and Ar as carrier gas between 400 and 700°C. The films were characterized by means of scanning electron microscopy and energy dispersive spectrometer. In this paper, the wear and corrosion resistance of TiN coatings have been investigated by abrasive experiments and corrosion tests. It was shown that coated samples demonstrated significantly higher wear resistance than those uncoated by weight loss measurements in the test procedure. Under the conditions of the corrosion experiments, substrates with TiN coatings showed better corrosion resistance than uncoated samples and stainless steel.
Directly Synthesis of Polymeric Nano-Composite from Waste Solid Absorbents of Treating Styrene Monomer-Containing Waste Gas
Authors: Huang Wu Jang , Chang Ling Yin , Wu Hsiu Hsien , Liou Yan Jia
Published: March 2009

This study aimed to synthesize polystyrene (PS)-TiO2 nano-composite from the waste solid absorbent directly, so that the waste TiO2/PS solid absorbent could be used as nano-materials. TiO2 powder with a particle size of 12 nm was used for the solid absorbent. The TiO2 packed scrubbing tube was used for treating synthetic waste gas that contained styrene monomer. Experimental results confirmed that the concentrations of styrene in synthetic waste gas can be reduced by 62% after the activation of photocatalyst, and the lifetime of activated TiO2 catalyst is over 2 hours. From the NMR and DSC spectra of obtained products, PS is actually grafted on the surface of TiO2. The glass transition temperature of obtained PS in TiO2/PS solid absorbent is 100oC.
Study on the Tribological Properties of Low-Power Plasma-Sprayed Al-Cu-Cr Quasicrystalline Coating
Authors: Fu Ying Qing , Zhou Feng , Yang De Ming , Li Nan Xiang , Gao Yang
Published: March 2009

Al-Cu-Cr quasicrystalline coatings were prepared by low power plasma spraying with axially-fed powder systerm. The Al65Cu20Cr15 powders were deposited on AISI 1045 steel substrate at the power ranged from 4.0 to 5.5 kW. The effects of H2/Ar flow ratio on the phase composition, microstructure and tribological properties of the as-sprayed coatings were investigated. The XRD results showed that the feedstock powders and as-sprayed coatings contained a predominant icosahedral quasicrystalline phase I-Al65Cu24Cr11 and three minor crystalline phases, including a body-centered cubic α-Al69Cu18Cr13, a monoclinic θ-Al13Cr2 (i.e. Al83Cu4Cr13) and a hexagonal ε-Al2Cu3. A qualitative analysis on the XRD patterns indicated that the volume fraction of any crystalline phase (α, ε or θ) in the coatings increased, while the quasicrystalline I-phase decreased with the rise of hydrogen (H2) content in the working gas. However, as increasing the plasma power, the friction and wear resistance of the coating were improved under the same dry sliding wear test conditions. The improvementincrease of the wear resistance may be attributed to the high hardness of quasicrystal.
Effect of Trace Element Erbium on Corrosion Resistance Properties of Al-Zn-Mg-Cu Alloy
Authors: Wang Xu Dong , Nie Zuo-Ren , Lin Shuang Ping , Su Xue Kuan , Xing Ze Bing
Published: March 2009

The intergranular corrosion and stress corrosion cracking resistance of Al-Zn-Mg-Cu alloy with trace Er addition were studied by means of such methods as stress corrosion cracking and intergranular corrosion test in GB-T7998-2005 and HB5254-83. The microstructures were observed by optical microscope and scanning electron microscope (SEM). The results show that alloys with trace Er addition have been improved on intergranular corrosion and stress corrosion cracking resistance, but corrosion resistance of alloys can be descending when Er addition exceed 0.4%.
Thermodynamic Research on Solution Properties of Al-Er Alloys
Authors: Zhan Chun Yao , Wang Wei , Tang Zhen Lei , Nie Zuo-Ren
Published: March 2009

Mixing enthalpy of Al-Er binary alloys system has been calculated based on Miedema model, in which a new interaction parameters Li proposed by George Kaptay was considered: Li=h0i.exp(－T/τ0i ), which are used to indirectly calculate the activity of Er in Al-Er alloys and some other thermodynamic properties, such as excess Gibbs energy and excess entropy at 1073K. Firstly the interaction parameter between Al and Er is worked out, then formation ability of alloy solution is analyzed. The results showed that interaction parameter vs temperature can be taken as the form of LAl-Er=－240.29 exp(－T/2000) kJ/mol, which indicates that Al and Er atoms have a great tendency to form intermetallic compound of Al3Er during solidification. The Er concentration shows a negative deviation from Rault’s law, mixing enthalpy, excess Gibbs energy and excess entropy are all negative in the whole range of concentration, which reveals that Al and Er could dissolve each other up the liquidus line.
Effect of Sr and Nd on Microstructure and Mechanical Properties of AZ91-1Si Alloy
Authors: Zou Zhi Wen , Xiong Shou Mei
Published: March 2009

In present work, trace elements Sr and Nd were added into AZ91-1wt%Si alloys. The alloys were cast into a permanent mould and then machined into test bars. The microstructure and mechanical properties at room temperature of the specimens were investigated. Results showed that complicated Chinese script Mg2Si phase decreased in size with the increase of Sr addition. When Sr addition increased to 0.1wt%, the Mg2Si phase was changed from Chinese script shape into uniform polygon shape completely. At the same time, mechanical properties improved due to the morphology modification of the Mg2Si phase. An intermetallic compound containing Mg, Al, Nd and Si was found when Nd was added to the alloy. Remarkable modification on the shape and distribution of the Mg2Si phase was observed because of the intermetallic compound, which leads to a great change in mechanical properties. The grain refinement mechanism of Sr and Nd elements on the Mg2Si phase was discussed.
Mechanical Properties and Microstructure of AM140 Magnesium Alloy
Authors: Li Yong Jun , Zhang Kui , Li Xing Gang , Zhao Xin , Mi Xu Jun
Published: March 2009

The homogenization treatment, hot extrusion, and annealing treatment are carried out to study the effects of these processes on the mechanical properties and structure of AM140 magnesium alloy. The parameter of homogenization treatment (420°C× 24h) determined by DSC and metallurgical photo is sufficient which ensures the eutectic phase melt into magnesium matrix greatly. The Rm, Rp0.2 and A of billets after hot extrusion are 355MPa, 305MPa and 3.5% respectively. The variation of structure and mechanical properties during the process of aging is also studied by optical observation and tensile strength .
Preparation and Property of the Environment-Friendly Anodizing Oxidation Coating of AZ31 Magnesium Alloy
Authors: Liu Yu Ping , Zhang Ding Fei , Chen Chang Guo , Shen Ying Ping , Zhang Jian Gang
Published: March 2009

This paper deals with an environment-friendly anodizing oxidation process for AZ31 magnesium alloy. Good anti-corrosion anodizing oxidation coating was prepared on the surface of AZ31 magnesium under 10 mA/cm2 constant current at 20°C after 20 min. The anodic film of AZ31 was ivory-white, dense, uniform, compact and porous structure. The anodic film of AZ31 mainly consisted of MgO, Mg2SiO4.According to Tafel curve and EIS,the anodic film of AZ31 had better anti-corrosion property than the substrate AZ31. This anodic film could increase the anti-corrosion property of AZ31 effectively.
Thermal Analysis on Vacuum Synchronous Reduction for the Preparation of Mg-Sr Alloy
Authors: Li Lei , Peng Xiao Dong , Wang Dong Ya , Xie Wei Dong , Wang Shou Cheng , Xu Xiao Ke , Wei Qun Yi , Su Zhong Hua
Published: March 2009

Mg-Sr alloy was prepared by the vacuum synchronous reduction method at a temperature of 1100°C. The phase composition of the reaction product and slag was analyzed by XRD. Results showed that Mg17Sr2 and α-Mg were formed in the product while Ca2SiO4 and Sr2SiO4 existed in the slag. DSC-TG curves obtained from thermal analysis of the reduction process indicated that vacuum was an essential condition in the preparation of Mg-Sr alloy by synchronous thermal reduction method when temperature was below 1200°C.
Effect of Plasma Interface Treatment and Cathodic Electrophoretic Coating on Mg Alloys
Authors: Zhang Jin , Li Ren Yu , Yu Qing Song
Published: March 2009

In this study, plasma treatment using Ar and H2 and plasma polymerization with trimethylsilane (TMS), were carried out to create the interface film systems with a structure of Mg/plasma interlayer/cathodic electrophoretic coating (E-coat) for a magnesium (Mg) alloy AZ31B. The interface adhesion of the coating system was evaluated using N-methylpyrrolidinone (NMP) paint removal test and ASTM tape test conducted under dry and wet conditions. Plasma TMS film could stick the Mg substrate more strongly than E-coat.The surface of samples with different interlayer treatment after NMP test has been observed by SEM. The potentiodynamic study performed on the E-coated samples showed a noticeable reduction of corrosion current, three orders of magnitude less than bare Mg. Salt spray test also was done to confirm the resistance corrosion of E-coat. It was found that plasma interface treatment has the ability of increasing the adhesion of E-coat on Mg alloy more or less, thus restrict access to damaging species that exist in Cl- aqueous environments.