bluuebunny/crossref_metadata_2025 huggingface dataset:
First-Principles Study of Optical Properties of Single-Wall Silicon Nanotubes
Authors: Kou Xiao Jing , Zhu Chun Bo , Fu Jia Cai
Published: April 2010

The optical properties of two kinds of single-wall silicon nanotubes (sw-SiNTs) [(n, 0) and (n, n)] with small diameters are investigated by using the first-principles method. For these two kinds of nanotubes, the absorptive part  of dielectric functions exhibits a broad band from 4 to 8eV in the region of 4-11eV, which is attributed to the transition of the  band to the * and  bands. Particularly, another small peak (inter- band transition) at 1.2-2.3 eV in the low-energy region is also identified. In addition, the loss function of these nanotubes are calculated and discussed.
Study on Ferroelectric and Dielectric Properties of Zr-Doped Sr2Bi4Ti5O18 Ceramics
Authors: Hao Ji Gong , Xu Zhi Jun , Chu Rui Qing , Zhang Yan Jie , Chen Qian , Li Guo Rong , Yin Qing Rui , Chen Na , Cui Min
Published: April 2010

Zr-doped Sr2Bi4Ti5O18 (SBTi) bismuth layer-structured ferroelectric ceramics were prepared and studied. XRD patterns revealed that all the ceramic samples were single phase compounds. SEM images showed that dense microstructures with uniform gain size were obtained in all samples. The effects of Zr4+ doping on the dielectric, ferroelectric and piezoelectric properties of SBTi ceramics were also investigated. It was found that Zr4+ dopant gradually decreased the Curie temperature (Tc), enhanced the remnant polarization (2Pr) and decreased the coercive field (Ec) of SBTi ceramics. Furthermore, the piezoelectric properties of the SBTi ceramics were improved by enlarging the content of Zr. The SBTi ceramics with 4 mol% of Zr4+ dopant exhibited good electrical properties: d33 = 21 pC/N, 2Pr = 14.3 μC/cm2, Tc = 251°C, εr = 376, tanδ = 1.8%.
Ferroelectric Properties and Microstructures of Tb4O7-Doped Bi4Ti3O12 Thin Films
Authors: Mei X.A. , Chen Min , Cai A.H. , Su K.L. , Huang Chong Qing , Wan Z.M.
Published: April 2010

Tb4O7-doped bismuth titanate (BixTbyTi3O12 BTT) thin films were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique, and the microstructures and ferroelectric properties of the films were investigated. Microstructure studies indicate that all of BTT films with well-developed rod-like grains consist of single phase of a bismuth-layered structure without preferred orientation. The experimental results indicate that Tb doping into Bi4Ti3O12 results in a remarkable improvement in ferroelectric properties. The remanent polarization (Pr) and coercive field (Ec) of the BTT film with y=0.6 were 22 μC/cm2 and 85 kV/cm, respectively.
BaTiO3 Functional Ceramics Thin Film Prepared by Self-Assembled Monolayers
Authors: Tan Guo Qiang , Zhang Cheng , Miao Hong Yan , Ren Hui Jun , Xia Ao
Published: April 2010

BaTiO3 thin film was prepared by the self-assembled monolayers technique and liquid phase deposition. The effects of pH values and the deposition temperature on the formation of BaTiO3 film were studied. The results showed that the Si substrate was in the precursor solution with 0.025mol/L (AHFT/BN/BA=1:1:3) and pH= 1.5. At 45°C deposited for 8h and annealed at 600°C for 2h, the BaTiO3 film with higher crystalline was prepared on the functionalized Si substrate. XRD and SEM tests showed that the film deposited in the precursor solution with different pH values appeared BaTiO3 characteristic peaks on the surface of every crystal. As pH values increased to 1.5 from 0.5, the strength of the film diffraction peak increased. But the width of the peak became smaller and the crystalline increased. When pH value was 2, due to the self-polymerized deposition of [Ti(OH)6]2-, it was easy to form the larger particles on the substrate. When the deposition temperature was 45°C, the acicular BaTiO3 film formed with the regular order and homogeneous planeness on the substrate. When the deposition temperature was between 55°C and 60°C, the dewatering and polymerizing speed between [Ti(OH)6]2- ions was higher than that between [Ti(OH)6]2- and -OH. The adsorption of the film to the Si substrate was weakened. It was easy for the film to fall off.
Effects of Sintering Additives on the Microstructure and Mechanical Properties of Silicon Nitride Ceramics by GPS
Authors: Zhang Wei Ru , Sun Feng , Tian Ting Yan , Teng Xiang Hong , Ru Min Chao , Ding Yan
Published: April 2010

Silicon nitride ceramics were prepared by gas pressure sintering (GPS) with different sintering additives, including La2O3, Sm2O3 and Al2O3. Effect of sintering additives on the phase-transformation, microstructure and mechanical properties of porous silicon nitride ceramics was investigated. The results show that the reaction of sintering additives each other and with SiO2 had key effects on the phase-transformation, grain growing and grain boundaries. With 9MPa N2 atmosphere pressure, holding 1h at 1850°C, adding 10wt% one of the La2O3, Sm2O3, Al2O3, porous silicon nitride was prepared and the relative density was 78%, 72%, 85% respectively. The flexural strength was less than 500MPa, and the fracture toughness was less than 4.8MPam1/2. Dropping compounds sintering additives, such as La2O3+Al2O3, Sm2O3+Al2O3 effectively improves the sintering and mechanical properties. The relative density was 99.2% and 98.7% with 10wt% compounds sintering additives. The grain ratio of length to diameter was up to 1:8. The flexural strength was more than 900MPa, and the fracture toughness was more than 8.9MPam1/2.
SrTiO3 Functional Ceramics Thin Film Prepared by Self-Assembled Monolayers with the Liquid Phase Deposition Method on Silicon Substrates
Authors: Ren Hui Jun , Tan Guo Qiang , Miao Hong Yan , Song Ya Yu , Xia Ao
Published: April 2010

In this article, (NH4)2TiF6, SrNO3 and H3BO3 were used as raw materials to prepare the precursor solution with the ratio of AHFT/SN/BA=1:1:3. The thin films of SrTiO3 were fabricated on the functional silicon substrates (100) by self-assembled monolayers (SAMs) with the liquid phase deposition (LPD). This article also studied the effects of wet state and the deposition temperature of the precursor solution before and after the functionalization of silicon substrate on the thin film growth. The results indicated that after the immersion in OTS for 30min, the surface contact angle of the silicon substrate changed from 24.64° to 100.91°. The substrate appeared hydrophobic property and it was irradiated by UV light for 30min. Then the surface contact angle of the substrate decreased to 5.00°. The substrate appeared hydrophilicity. The concentration of the precursor solution was 0.025 mol/L, the deposition temperature was 40°C and the deposition time was 9h, which were all helpful to SrTiO3 crystallization. XRD and SEM were used to characterize the physical phase of thin film and surface morphology at 600 °C with annealing and heat retaining for 2h. The results indicated that the thin film prepared by the mono-crystal Si substrate was SrTiO3 thin film with better crystalline. On the crystal surfaces of (110), (100), (200) and (211), there appeared the obvious diffraction peaks. The SrTiO3 grains on the surface had the clear outline and were regular and long columnar crystals.
A Study on the Disk-Type Piezoelectric Transformer of Mg:LN Single Crystal
Authors: Zhang Ming Fu , Guo Huai Xin , Zhang Hai Liang , Xu Cheng Hai , Zhao Ye Quan , Han Jie Cai
Published: April 2010

In this study, a disk-shaped step-down piezoelectric transformer that consists of Mg:LN single crystals operating in the extensional vibration mode was proposed, and its characteristics wre investigated. This paper proposed the PT using ring/dot electrode which had an outer diameter of 22 mm, a narrow annular gap circle of 1.0 mm and a thickness of 1.0 mm. The transformer was poled along the thickness direction. The top surface was covered by two ring-shaped electrodes separated by a narrow annular gap, and the regions covered by the outer and inner ring electrodes serve as the output and input parts of the transformer, respectively. The bottom surface was fully covered with a gold electrode. Moreover, according to the physical equivalent circuit model of the latest invented vibration mode, PT of Mg:LN single crystals were fabricated and characterized. Finally, we investigated the gain under different load resistances and input voltage.
Synthesis and Identification of a Hyperbranched Polymer of Tris(8-hydroxyquinoline) Aluminum Linked with Ethylene Glycol
Authors: Song Bo , Xiang Jun Hui , Zhang Fu Shi , Xing Li , Liang Xiao Hong , Chen Shi Wei
Published: April 2010

In this paper the authors discribed the convergent synthesis of a novel hyperbranched polymer, tris(8-hydroxyquinoline) aluminum (Alq3) linked with ethylene glycol, and the indentification of the polymer by UV/vis spectra, photoluminescence spctra(PL),1H NMR spectra, element analysis (EA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), thermal gravimetric analysis (TGA), Cyclic voltammetry (CV), etc.. By introducing Alq3 into the hyperbranched polymer, which was connected with alkoxy chain, the electron injection and transport properties were improved. The maximum absorption peak of the polymer is 58nm blue-shifted, but the emission peak of the polymer is 32nm red-shifted to Alq3 in chloroform soltion. The optical energy band-gap estimated from the absorption edges is 2.845eV. These optical characters of it indicated that the operation, connecting Alq3 with ethylene glycol, could increase the energy band-gap but make the photos easier to transfer between the HOMO and LUMO energy levels.
Saturation Effect of Al(NO3)3 Dopant on Residual Voltages of ZnO Based Varistor Ceramics
Authors: Long Wang Chen , Hu Jun , He Jin Liang , Liu Jun , Luo Feng Chao
Published: April 2010

The additive of Al(NO3)3 was doped into ZnO varistors in order to reduce their residual voltages. Some of doped Al3+ enter the ZnO grains and infill into the vacancies of Zn2+ ions in the crystal lattice. Then, the resistances of ZnO grains decrease, which finally results in lower residual voltages of varistor samples. However, when most of Zn2+ vacancies inside the ZnO crystal lattice are filled with Al3+, redundant Al3+ ions inside ZnO grains will increase the grains’ resistances contrarily. In this paper, ZnO and Al(NO3)3 binary ceramics sintered at 1300 °C for 2, 4 and 8 hours were studied. The J-E curves of the investigated samples exhibit weak non-linear characteristics which may be due to the formation of grain boundary. Moreover, The resistivity dependence of ZnO ceramics on Al addition behaves as a U-type curve and the lowest resistivity of ZnO ceramics is obtained with doping 0.25mol% Al3+.
Preparation and Characterization of Different Metal Modified BaTiO3 Powders
Authors: Li J.L. , Hao S.E. , Wang C.Y. , Kong F.X. , Wang W.
Published: April 2010

BaTiO3 powders modified with Sm, La, Cu, Al, Zn were prepared by solid doping and gaseous penetration method and their components, structure, superficies and electric properties were characterized. The results show that the resistivity of the modified powders is decreased after both solid doping and gaseous penetration, and it is more obviously after gaseous penetration. Among all the metals being discussed, Sm has the most significant influence on decreasing the resistivity of modified powders. The room temperature resistivity of Sm-penetrated BaTiO3 powders is the lowest, which decreases from 8.3×1010Ω•m (pure BaTiO3 powders) to 1.65×105Ω•m. SEM investigation illustrates that the powders are in uniform grain size. No apparent pores and small grains are found. XRD analysis indicates that the doping process only leads to the changes of the peak width and intensity without new phases appearing, but characteristic peaks of Sm2TiO5, SmTiO3, and Ba10.37Sm17.08Ti36O108 can be detected after gaseous penetrated, which leads to the decrease of the resistivity of modified BaTiO3 powders.
Preparation and Dielectric Properties of 1-3 La Modified PZT/IPN Piezoelectric Composites
Authors: Zhu Z.L. , Tang Dong Yan , Zhang X.H. , Qiao Y.J.
Published: April 2010

To prevent the potential cracking of gel fibers, La modified lead zirconate titanate (PLZT) ceramic fibers with diameter within 50µm were achieved by embedding into PLZT powders during the heat treatment. Then the 1-3 PLZT fiber/interpenetrating polymer network (IPN) piezoelectric composites were prepared by casting the IPN precursors onto the well aligned ceramic fibers. The influences of the heating temperatures and La amounts on the dielectric constant, dielectric loss with frequencies and piezoelectric constant of PLZT were investigated in detail. The morphologies of fibers and composites were observed by biological microscope. And also, the dielectric constant of PLZT fibers and PLZT fiber/IPN piezoelectric composites were detected.
Preparation and Luminescent Properties of Green-Emitting La(BO3,PO4): Ce, Tb
Authors: Dong Li Min , Zhuang Yan Li , Han Zhi Dong , Wu Ze , Zhang Xian You
Published: April 2010

Green phosphor of La(BO3, PO4): Ce, Tb was synthesized by means of sol-gel method and conventional solid state method. The thermal formation process was characterized by thermogravimetric analysis (TG) and (DTA). The effects of synthesis method and conditions on the crystal and morphological structure were investigated by (XRD) and (SEM). The results revealed that La (BO3, PO4): Ce, Tb phosphors with monocline structure and high purity were successfully prepared by sol-gel method. Compared with solid state method, the products synthesized by sol-gel method presented well developed crystal structure, small particle size, narrow size distribution and high luminescent performances. The product synthesized at 1050°C for 2h had better emission intensity.
NaAc Effect on the Anodization Formation of TiO2 Nanotube Arrays in Glycerol Based Electrolytes
Authors: Yin Yu Xin , Tan Xin , Hou Feng
Published: April 2010

Effect of NaAc on the anodic growth of TiO2 nanotube arrays is described. NaAc-added approach yields longer nanotubes relative to samples grown from NaAc-free electrolyte. And the growth rate of TiO2 nanotubes has pH independency in NaAc-added electrolytes. The key to achieve a high aspect ratio TiO2 nanotube arrays is to decrease the chemical dissolution rate at the mouth of the tube by adding NaAc as protective coating. Adsorption of Ac- species on the TiO2 surface is shown to markedly decrease the chemical dissolution rate of the tube mouth, resulting in longer nanotube length.
Investigation of the Reaction Time and the Process of Synthesis of GaN Nanopowders by Ammoniating Ga2O3
Authors: Xue Xiao Shuang , Wang Fen , Zhu Jian Feng , Yang Hai Bo
Published: April 2010

GaN nanopowders were synthesized by ammoniating pure Ga2O3 powders at 1000°C for different soaking time. The results show that the growth of GaN at this temperature is based on vapor-solid mechanism. The ammoniating reaction finished and the rearrangement process started when the soaking time is 0.5 h. When the soaking time is 1.5 h, the process of high-temperature aggradation transformed to thermal decomposition-re-crystallization process. Further increasing of soaking time, the fabricated GaN particles with large size aggregated by directional fixed nanorods are substituted by self-governed particles, which agglomerate as honeycomb. Photolumine- scence measurement (PL) test reveals that as prepared sample with 1.5 h possesses the best luminescent property.
Preparation and Characterization of Polycrystalline Cubic Boron Nitride (PcBN) Compacts by a Pressureless Sintering Process
Authors: Ren Zhen Huo , Zhang Rui , Wang Hai Long , Chen De Liang , Li Ming Liang
Published: April 2010

A novel cost-effective pressureless sintering method has been developed to prepare polycrystalline cubic boron nitride (PcBN) compacts. The effect of feldspar as sintering aids was analyzed in this paper. Various amounts of feldspar from 5 to 15 wt% were added to cBN powders, and the pressureless sintering was conducted at temperatures ranging from 900°C to 1200°C under an air atmosphere. The microstructure, phase, density and microhardness of the as-obtained PcBN compacts were measured and correlated to amounts of Si added and to sintering temperatures. The sample showed superior sintering behavior in comparison to those fabricated using hot pressed sintering. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that feldspar diffused homogeneously and tightly bonded with cBN. But hBN appeared when the sintering temperature even at 900°C, which dramatically affected the property of PcBN compacts. A PcBN compact with a relative density of 91% was obtained at 1100°C and its microhardness was as high as 1000HV.
Microwave Absorption of BaLa0.5Fe11.5O19/SiO2 Nano-Powders
Authors: Han Zhi Dong , Zhao Qing Rui , Dong Li Min , Wu Ze , Zhang Xian You
Published: April 2010

Nano-size BaM hexaferrites (BaLa0.5Fe11.5O19) were synthesized in the presence of SiO2 nano- particles by sol-gel method. The X-ray diffraction (XRD) patterns of ferrites annealed at above 900°C manifested that all the species had hexagonal crystal structure and no diffraction peaks of SiO2 found. Compared with BaLa0.5Fe11.5O19 powders, those synthesized in the presence of SiO2 nano-particles presented in smaller powder size, as proved by scanning electron microscopy (SEM). As a result, SiO2 nanoparticles promoted the formation of more homogeneous and finer ferrite crystal while the structure of hexaferrites consisted with that synthesized without SiO2 nano-particles. Microwave absorbing properties were evaluated. As a result, BaLa0.5Fe11.5O19/SiO2 showed good microwave absorbing properties with the maximum absorption more than 20dB.
Influence of Ca0.6Mg0.4Zr4(PO4)6 Coating on Alkali Corrosion Resistance of SiC Ceramic
Authors: Zhou Jian Er , Zhang Xiao Zhen , Peng Shi Jiang
Published: April 2010

Ca0.6Mg0.4Zr4(PO4)6 coating was used as environmental barrier coatings (EBC) to improve the alkali corrosion resistance of SiC ceramic at high temperature. A new sol-gel based process has been developed for preparing high quality and thick C0.6M0.4ZP coating on SiC ceramic with once deposition. The prepared C0.6M0.4ZP coating on SiC ceramic is homogeneous and dense, and shows a thickness of about 200 μm when sintered at 1400 °C for 3h. The effectiveness of C0.6M0.4ZP coating in improving the alkali corrosion resistance of SiC ceramic was evaluated based on the SEM microstructural analysis, mass change and flexural strength measurements after being subjected to alkali Na-salt attack at 1000 °C for 96 h. Significantly improved alkali corrosion resistance was confirmed for SiC ceramic using C0.6M0.4ZP coating as EBC.
Structure and Dielectric Properties of (Gd0.4Sm0.5Yb0.1)2(Zr1-xCex)2O7 Ceramics
Authors: Liu Ling , Xu Qiang , Wang Fu Chi
Published: April 2010

Complex rare-earth zirconates (Gd0.4Sm0.5Yb0.1)2(Zr1-xCex)2O7 (x=0, 0.3, 0.4) powders were synthesized by co-precipitation method. XRD and SEM results revealed that the complex rare-earth zirconates with single pyrochlore structure were prepared and no other phases existed among the grains. The dielectric properties of these compounds were investigated at low and microwave frequencies. It was found that they have intermediate dielectric constants and low dielectric loss in the whole frequency region, and they show the dielectric permittivity with weak frequency dependence. Substituting Zr4+ by Ce4+ leaded to smaller permittivity. Meanwhile, the dielectric contant values increase with increasing in the r(A3+)/r(B4+) value in the pyrochlore-type phase region, which can be explained by the increase in the degree of ordering of oxygen vacancy. This new series of pyrochlore type oxides would be potential candidates for electronic ceramic applications and microwave frequency components.
Thermal Conductivity of Sm2Zr2O7-Carbon Nanotube Composite
Authors: Liu Xiao Xiao , Xu Qiang , Cai Hong Nian
Published: April 2010

CNT (carbon nanotube) was purified by acid washing method and then dispersed in alcohol. Sm2Zr2O7-CNT composite powders containing different amounts of CNT were synthesized by corprecipitation method and hot-press sintering were selected to prepare the composites. The density and thermal conductivity of the samples were tested. The micro-morphology and phase structure of composites were characterized by field emission scanning electron microscope and X-ray diffraction, respectively. Based on these experiments and theoretical analyses, the influences of carbon nanotube on the micro-morphology, phase structure and thermal conductivity of Sm2Zr2O7-CNT composite were revealed. Results showed that the carbon nantube uniformly dispersed in Sm2Zr2O7 matrix and the thermal conductivity of composites varied with the different amounts of CNT. In this article, the variation of thermal conductivity can be explained by the comprehensive evaluation of Sm2Zr2O7, CNT, pore and the heterogeneous interfaces thermal resistance between matrix and additives.
Spraying Distance and Oxidation Resistance of Electrothermal Explosion Sprayed MoSi2-Based Coatings
Authors: Hou Shi Xiang , Liu Zong De , Liu Dong Yu , Zhao Li Ping
Published: April 2010

Intermetallic compound MoSi2 is useful for protective coatings against high-temperature oxidation. In this study, MoSi2-based coatings were prepared using electrothermal explosion ultra-high speed spraying methods. The spraying distance from electric exploding chamber to substrate are 5mm, 10mm, 15mm and 20mm, respectively. The microstructures, phase structures and hardness of the coatings were investigated by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Vickers hardness tester, respectively. The result indicates that MoSi2 primary phase is synthesized. When spraying distance is 10mm, the coatings have density microstructure, submicron grains and high microhardness. The bonding of coating-substrate is metallurgical. The oxidation resistance of Mo-Si-Al coating is higher than that of Mo-Si coating.
Structure and Properties of Ductile Iron Strengthened by Laser Surface Alloying
Authors: Xu Jing , Wang Wen Yan , Xie Jing Pei , Li Ji Wen , Wang Ai Qin
Published: April 2010

The wear resistance, corrosion resistance, high temperature resistance layers were prepared on the surface of ductile iron via laser alloying process, using the mixed ponder of sub-micron carbides power as starting materials. The microstructures of the different laser alloying layers were characterized by XRD, SEM, EDS, TEM. The microhardness and wear resisitance of the laser alloying layers were examined. The results reveal that the flat alloyed coating combines metallurgically with the substrate. the laser area was composed by alloyed zone ,heat-affected zone and matrix zone. The alloyed zone was composed mainly by ledeburite and carbide, while martensite and retained austenite were contained in the heat affected zone, there is no significant change in the Matrix zone. Under conditions that the laser power, spot diameter remain unchanged, with in 400 ~ 1000 mm/min scanning speed, the hardness of alloyed coating increases with increasing scanning speed. The weightlessness of the alloyed samples under the dry sliding friction is one-sixteenth of ductile iron. The wear resisitance of the alloyed coating has improved significantly.
Friction and Wear Characteristics of Laser-Clad Nano-Lubricating Coating
Authors: Wang Wen Yan , Xu J. , Xie Jing Pei , Yan H. , Wang A.H.
Published: April 2010

Nickel-based nano self-lubricating coatings were deposited on medium carbon steel by laser. The microstructure and tribological properties of the typical coating containing 10wt % nano-hBN powders were investigated using SEM incorporating EDS, and high temperature tribo-tester, respectively. It was found that the cladding layer and substrate was good metallurgical bonding. Dry sliding frictional tests suggested that the composite coating containing about 10wt % hBN powders has lower friction coefficient than that of pure Ni60 cladding at room temperature with a load of 40N and a speed of 2m/s, as well as 400°C with a load of 20N and a speed of 2m/s. The wear resistance of Ni60-hBN coating is about 10 times than that of Ni60 coating. The SEM analysis of the abrasion morphology found that wear mechanism of self-solid lubrication coating was adhesive wear, and wear mechanism of the cladding layer of non-lubricant was adhesive wear with abrasive wear.
Plasma Enhanced Microarc Oxidation on the Surface of Al–Cu–Mg Alloy
Authors: Li Shu Hua , Zhang Long , Tan Cheng Wen
Published: April 2010

Alumina coatings were synthesized on Al–Cu–Mg alloy substrates through the Plasma enhance microarc oxidation (PMAO) route. Different oxidation times namely 1, 3, 5, 10, 20 and 30 minutes were employed and the coated samples were subjected to coating thickness and surface roughness measurements. Phase composition of the surface layers of the coatings was evaluated through X-ray diffraction. In addition, influence of the oxidation time on the kinetics of the coating formation, surface roughness and microhardness were investigated.
Wear-Resistant Properties of TiC/Fe Ceramic Composite Coating on Steel Plate via Combustion Synthesis
Authors: Zhao Hong , Yang Shi Wei , Qiao Ying Jie , Zhang Xing Hong
Published: April 2010

The highly dense TiC/Fe ceramic coating was fabricated on Q235 steel surface by self- propagating high-temperature synthesis combined with pseudo hot iso-static pressing. The wear-resistant properties were examined by means of ball-on-disk contact wear test. The microstructure of TiC/Fe cermets coating was investigated. The results show that TiC/Fe cermets coating has an excellent wear-resistant property. There is little mass loss after 1200s under 30N loading under the condition of dry sliding wear testing. The major wear mechanisms are described by the following stages: sticking friction, grain abrasion and stripping of hard phase.
Effects of Content of Al2O3 Particles and Heat Treatment on Corrosion Resistance of Ni-P-Al2O3 Composite Coatings
Authors: Lu Jian Hua , Sun Wan Chang , Zhu Ming , Tan Ming Feng , Zhou Quan
Published: April 2010

Ni-P-Al2O3 composite coatings with the uniform distribution of Al2O3 particles were prepared by adding Al2O3 particles into Ni-P plating solution and adopting optimum plating process. The morphology and microstructure of the coatings were investigated by using SEM, EDS and XRD. Being immersed in 10 vol.% H2SO4 solutions, the corrosion resistance of Ni-P-Al2O3 composite coatings was tested. The results show that when the solubility of Al2O3 particles in plating solution is 8 g/l, the corrosion resistance is best. Comparing with as-plated Ni-P-Al2O3 composite coatings, the corrosion resistance of heat-treated Ni-P-Al2O3 composite coatings decreases by raising the temperature to 300°C and then increases by raising the temperature to 450°C.
Effect of Pulsed Substrate Bias on Evolution of Surface Morphology and sp3 Hybridization Degree of Ag-DLC Films in a Mid-Frequency Dual-Magnetron Sputtering
Authors: Yu Xiang , Yang Yi Yong , Wang Cheng Biao
Published: April 2010

In this work, we have investigated the influence of the pulsed substrate bias voltage on the evolution of the surface morphology and sp3 hybridization degree of Ag containing diamond-like carbon (Ag-DLC) films deposited by using a mid-frequency dual-magnetron sputtering system. The unipole substrate bias voltage at 0 V, -60 V, -100 V and -150 V, respectively, was employed on AISI 440 substrate with the duty ratio uniformly set at 70%. The surface morphology was observed by AFM and the hybridization degree of the DLC films was performed respectively using Raman Spectroscopy and Rockwell C indenter. In these samples, the surface morphology and sp3 hybridization degree of Ag-DLC films show a certain dependence on the pulsed substrate bias applied. The evolution tendency of the surface morphology is found different with that of the sp3 hybridization degree of the DLC films under action of the pulsed substrate bias. These phenomena imply that the energetic particles may induce a balance between recombination of the particles and change of the internal stress in the DLC films.
Influence of Target Current on the Structure of Ti-Doped DLC Films
Authors: Wang Cheng Biao , Fu Zhi Qiang , Yue Wen , Peng Zhi Jian , Yu Xiang , Lin Song Sheng , Dai Ming Jiang
Published: April 2010

Ti-doped DLC films were synthesized from C2H2 and Ti by ion beam deposition and magnetron sputtering, and the influence of Ti target current on the structures and the friction coefficients of Ti-doped DLC films were studied by SEM, AES, XPS, a ball-on-disk friction tester. The Ti content in Ti-doped DLC films is below 1at% when Ti target currents rise up to 3.5 A; but when Ti target current exceeds 3.5 A, Ti content in the films is obviously increased with increasing Ti target current. Ti-doped DLC films have a smooth dense surface with several particles dispersed in it and the surface morphology deposited with different Ti target currents is similar. With the augment of Ti target current, the ratio of sp3-C to sp2-C is almost a constant first, and then an obvious rise followed by an abrupt decrease is found; but only when Ti target current is above 5A, the ratio of TiC-C to sp2-C is obviously increased with Ti target current. The lowest friction coefficients are obtained for the Ti-doped DLC films with the highest ratio of sp3-C to sp2-C and a low ratio of TiC-C to sp2-C.
Microstructure and Erosion Behavior at Elevated Temperature of Thermal Sprayed Fe-Al/WC Coating
Authors: Tian Bao Hong , Liu Yong
Published: April 2010

A Fe-Al/WC composite coating was fabricated by using high velocity arc spraying (HVAS) and cored wire. The elevated temperature erosion behaviors of the coating were investigated with a grit blasting type erosion tester. The coating microstructure and eroded surface morphologies were analyzed by energy dispersion spectroscope (EDS), X-ray diffraction (XRD), scanning electron microscope (SEM) , transmission electron microscope (TEM) and image analyzer. The effects of incidence angle and test temperature on the erosion behavior were determined.
Photocatalysis and Hydrophilicity of Y3+ Doped TiO2 Thin Films
Authors: Xu Wen Yuan , Luo Ming Biao , Wei Lu Bin , Liu Yun Hai , Lin Hai Lu
Published: April 2010

Y3+ doped TiO2 coatings were successfully prepared on glass slide substrates. The phase structure, optical properties，microstructure and surface properties of the coatings were characterized by using XRD, FT-IR, UV-vis and SEM. The photoinduced super-hydrophilicity and photocatalytic activity of the films were evaluated by the water contact angle measurement and photocatalytic oxidation of Rhodamine B in air, respectively. The results indicated that the doping of Y3+ into TiO2 could improve the hydrophilicity and photocatalytic activity, and TiO2 thin films doped with Y3+ at 2-4 at.% and heat-treated at 450 oC were of super-hydrophilicity. The optimal Y3+ content for the photocatalytic activity was 4 at.% and larger film thickness was helpful to reduce the contact angle of the composite films.
ZrO2 Thin Films Prepared by Self-Assembled Method
Authors: Xia Ao , Tan Guo Qiang , Miao Hong Yan , Song Ya Yu , Bo Hai Yang
Published: April 2010

Octadecyltrichlorosilane (OTS) was prepared on glass substrate to form self-assembled monolayer (OTS-SAM). The OTS-SAM was then UV-irradiated to endow the film with good chemisorption ability. Zirconia films were formed on silanol SAM by the LPD method. The phase structure and surface configuration of the zirconia films were studied by XRD and SEM respectively. The XRD results indicate that the as-deposited ZrO2 thin films are pure tetragonal phase after being annealed at 500°C for 1 h. SEM images show the zirconia film is uniform, but not very compacted.
Microstructure and Properties of Interface High-Speed Steel Reinforced by In Situ VC /35CrMo Compound Roll
Authors: Li Yan , Wei Shi Zhong , Xu Liu Jie , Xu Chun Wei , Long Rui
Published: April 2010

The high-speed steel (HSS) reinforced by in-situ VC /35CrMo compound roll was produced by electromagnetic semicontinuous casting. The element distribution and the structure morphology of the interface were analysed, and the mechanical properties were tested. The results indicate that the thickness of diffusion layer is around 50μm. The microstructure of the diffusion layer is pearlite, and next to the diffusion layer, the microstructures are ferrite and pearlite at the alloyed steel side. There are in-situ VC particles in martensitic matrix. At the high-speed steel side. The microhardness of HSS and 35CrMo is about 700HV and 250HV, respectively, and that of diffusion layer is near 350HV, which is between that of HSS and 35CrMo. The impact toughness is 100 Jcm-2. On the basis of the experiment, the interface of compound roll prepared by electromagnetic semicontinuous casting obtains good microscopic structure and mechanical properties, which are the results of the metallurgically bonded interface.
Interface and Wear Resistance of High Frequency Induction Remelted Ni-Based WC Coating
Authors: Zhang Hong Xia , Luo Cheng , Zhao Hong Li , Hu Shu Bing
Published: April 2010

Ni-based WC composite coatings conducted on the surface of 45 steels by free spraying followed with high frequency induction remelting were investigated. The influences of induction remelting time on properties of the coating were discussed. The wear resistance of the coating and the elemental diffusion cross the interface between the coatings and the substrate were analyzed. The compositions and microstructure of the coating before and after a wear test were characterized by scanning electron microscope with energy dispersive X-ray microanalysis. The results indicate that a coating which is free from crackers and pores composed of Ni-based solid solution and dispersed tungsten carbide is obtained by free spraying and induction remelting. The interface is a white lamellar zone. The mutual diffusion of iron and nickel in the interface proves it’s an atomic bonding between the substrate and the coating. The wear mechanisms of the coated sample are abrasive wear and microplowing. The wear resistance of Ni-based WC composite coatings is superior to that of quenched high carbon steels.
Effect of Pigmentation on Strength of Dental Y-TZP/Porcelain Bilayered Structure
Authors: Yi Yuan Fu , Wang Chen , Wen Ning , Wang Xiao Ling , Yang De Sheng , Tian Jie Mo
Published: April 2010

The purpose of this study was to investigate the effect of pigmentation on the flexural strength of dental Y-TZP/porcelain layered structure. KaVo™ Everest zirconia substructures was pigmented by dipping presintered blocks in coloring solution, and colored TZ-3YS zirconia substructures were fabricated by adding pigments before isostatically pressing. Specimens were made in monolithic or bilayered forms. The bending strength was tested. XRD and SEM with EDX were used to analyze the characteristics of the surface structure. Experimental results showed that there were significant differences of bending strength in both zirconia systems between white and colored monoclinic materials, which also in bilayered structures. Pigmentation has no apparent effects on the bonding strength between veneering porcelain and zirconia. Both coloring methods are appropriate when the concentration of pigments is under deliberate controlled.
Effects of Veneering Porcelain Type on Bending Strength of Dental Y-TZP/Porcelain Bilayered Structure
Authors: Deng Bin , Liu Hong Chen , Yi Yuan Fu , Wang Chen , Wen Ning , Tian Jie Mo
Published: April 2010

The purpose of this study was to investigate the effect of different veneering porcelain types on the flexural strength of dental Y-TZP/porcelain layered structure. KAVO™ Everest zirconia ceramics were selected as substructure. To forming Y-TZP/porcelain bilayered structure, a leucite based veneering porcelain was fired on the zirconia substructures by slip-casting technique with dentin washbake, and two nano-fluorapatite based veneering porcelain was fired on the zirconia substructures either by slip-casting or pressed-on technique with or without liner coverage. Bending strength was tested according to ISO 6872 standard, and the veneered surfaces of fracture samples were analyzed by SEM. Experimental results showed that for covering KaVo™ zirconia core material, conventionally applied veneering slurry-porcelain combined with liner or wash firing has significant higher bending strength than pressed-on porcelain. SEM showed that the main failure type at the interface was adhesive.
Bonding Strength Between Zirconia Core and Different Veneering Ceramics
Authors: Hu Yi Wen , Zhang Xin , Wu Yin , Si Wen Jie
Published: April 2010

Zirconia ceramics are now widely used in dental restorations. The veneering porcelain chipping happens sometimes in zirconia-porcelain all-ceramic system. The objective of this study was to evaluate the bonding strength between the zirconia core and various commercial veneering ceramics. The shearing and bending methods were used to evaluate the bonding strengths of zirconia core and four veneering ceramics. Meanwhile, as surface treatment will play an important role for the bonding strength, the influence of 3 kinds of surface treatment was investigated. The results indicated that both the shearing and bonding strengths of Cercon ceram kiss is better. Moreover sand blasting is the most useful method of surface treatment.
Influence of Background Color on the Chromatic Value of Four All-Ceramic System Core Materials
Authors: Shao Long Quan , Wen Ning , Zhang Wei Wei , Liu Qi , Tian Jie Mo
Published: April 2010

This study aims to investigate the effect of background color on the chromatic value of four all-ceramic system core materials at clinically appropriate thicknesses. Disc specimens with 15 mm in diameter and thicknesses ranging from 0.5±0.01mm In-Ceram zirconia core, Cercon base zirconia core, and Cercon base color zirconia core) to 0.8±0.01mm (Empress II) were fabricated. A colorimeter (CIE- 1976-Lab) measured the chromatic value of all samples placed on a high-noble metal-ceramic alloy and a visible light-cured dental composite resin (A2 color) background, after which the color difference was calculated. The color difference of Empress II samples was more than 1.5 among different background color groups, while that of Zirconia was less than 1.5. The influence of background color on the Empress II dentin was visible, such that it could be used on a tooth color post. Meanwhile, the influence of background color was invisible for the three kinds of Zirconia core materia1s, such that the materials developed excellent color-masking abilities and could be adapted for use on any color background.
Effects of Presintering Temperature and Heating Rate on the Physical and Mechanical Properties of Alumina-Glass-Composites
Authors: Liu Jie , Shao Long Quan , Yi Yuan Fu , Deng Bin , Zhang Wei Wei , Dong Li Min , Liu Hong Chen , Tian Jie Mo , Wen Ning
Published: April 2010

Objective: To study the effects of presintering temperature and temperature rise speed on the physical and mechanical properties of alumina-glass-composite (AGC). Methods: AGC was prepared respectively under the condition that presintered at 1400°C and 1450°C as well as two kind of temperature rise speed. The properties were measured, including density, thermal expansion coefficient, three-point bending strength, fracture toughness, modulus of elasticity and Vicker’s hardness of AGC. Results: With the increasing of presentering temperature and the temperature rise speed, density of AGC decreased, bending strength, fracture toughness, modulus of elasticity increased markedly. There was no difference between three-point bending strength and fracture toughness of AGC that was made by two temperature rise speed to 1450°C. Bending strength of AGC that was made by lower temperature rise speed to 1400°C was the lowest. The Vicker’s hardness of the 1450°C groups was higher than that of the 1400°C groups. Conclusion: Both presintering temperature and the temperature rise speed can influenced the properties of AGC, but the effect of presintering temperature was the most.
Size Dependent Stiffness of Composite Ceramic with Partial Debonding Interphase
Authors: Liu Xie Quan , Li Bao Feng , Zhao Lei , Zhong Guo Hui
Published: April 2010

The partial debonding interphase has large influence on the behaviors of composite ceramic. The emerging cause of partial debonding interphase is interpreted and the interaction between particles and partial debonding interphase is accounted for determining the equivalent eigen strains by using the four phase model method. Then the effective stiffness of composite ceramic is estimated. The results show the effective stiffness is associated with the stiffness of the matrix and particles, the volume fractions of particles and partial debonding interphase, the subtending angle and thickness of partial debonding interphase.
Induction of Hydroxyapatite Particles Formation on PEGDA-Based Hydrogels by Nanobacteria
Authors: Tan Guo Xin , Ning Cheng Yun , Zhang Shu Jiang
Published: April 2010

Nanobacteria is a tiny structure with size varying 80 to 500nm, commonly occurring in clusters and producing a biofilm which contains carbonate or hydroxyl apatite. In this study, the bioactive synthetic hydrogel materials were prepared with polyethylene glycol diacrylate (PEGDA) and 2-hydroxyethyl mathacrylate (HEMA) by UV photo-polymerization. Bone marrow mesenchymal stem cells (BMSCs) were seeded onto hydrogel surface for five days. The BMSCs cell adhesion on hydrogels was confirmed by SEM to evaluate the biocompatibility of the materials. It was found groups of nanoparticles on the hydrogel surface and the particles were analyzed by SEM. The particles were analyzed for its inorganic chemical constituents using energy dispersive X-ray microanalysis (EDS). The predominant components were found to be calcium (24.40%) and phosphorus (13.98%). The most likely source of cell culture contamination by such organisms is bovine serum albumin (BSA) used as supplement in culture media. Nanobacteria in BSA may be the important factor which accelerated hydroxyapatite crystal growth on hydrogels. It is important to study the biomineralization in biological system and has potential application in biomaterials science and biotechnology.
Influence of Y2O3 Additive on Transparent of ALON Ceramics
Authors: Jiang Hua Wei , Du Hong Bing , Tian Ting Yan , Wu Hong
Published: April 2010

Transparent ALON ceramics with the ultra-fine -ALON spinel powder were prepared by hot-pressing. The powder was prepared by carbothermal reduction method. The optimum condition was hot-pressing between 1850°C to 1920°C for 3 ~ 5 h under 35 MPa. We got transparent samples 70 × 3 mm with in-line transmittance above 70% in the range from the visible to infrared wavelength. The effect of additive contents on transparency and the relation of microstructure and transparency have been discussed in this paper. The transmittance is good when the Y2O3 sintering additive content is 1.5wt%. The sample density is about 99% of its theoretical density. We also measured the flexural strength, elastic modulus and other mechanical properties of ALON.
Preparation of Aluminum Oxynitride Spinel γ-ALON Powders and Transparent Ceramics
Authors: Sun Cheng Gong , Niu Jin Ye , Wang Chong Hai , Zhou Chang Ling , Feng Bao Lin , Fan Jie , Wang Yan Yan , Hao Jian Shan
Published: April 2010

With AlN, Al2O3 and Al powders as starting materials, ALON powders were prepared by high temperature solid state reaction at 1650°C, 1750°C and 1850°C respectively. Nitrogen gas at 1atm was selected as reaction atmosphere. X-ray diffraction analysis and scanning electron microscope analysis were carried out for the as-prepared ALON powders. In this paper, single-component γ-ALON porous materials were obtained at temperatures below 1800 degree with void ratio more than 75%, which is prone to be grinded to powders less than 1μm and applicable for the preparation of transparent ceramics. Aluminum oxynitride spinel γ-ALON transparent ceramics were successfully obtained with the as-prepared ALON powders. The volume density of the transparent ceramics was 3.67g/cm2, which is 99.3 percent of the theoretical density of γ-ALON materials. The bending strength of the transparent ceramics was 296MPa and the transmittance was about 75% in the wavelength range of 1.2 to 5.3μm.
Thermoluminescence and Optical Stimulated Luminescence Studies of Sapphire
Authors: Zhang Hai Liang , Zhang Ming Fu , Han Jie Cai , Yang Hai , Xu Cheng Hai , Guo Huai Xin
Published: April 2010

Sapphire crystals grown by an improved Kyropoulos-like method were irradiated by gamma rays and electrons in this paper. Thermoluminescence (TL) and optical stimulated luminescence (OSL) properties of sapphire were studied. TL glow curves of sapphire were varied within the room temperature to 500°C at a heating rate of 10min•s-1. The OSL spectra wavelength covered were from 200nm to 700nm. There was a new peak at 220°C, which was produced by the irradiation of gamma rays and electrons. Two broad bands at 330nm and 410nm were found in the luminescence spectra, which were due to transitions of two charge states of an anion vacancy defect, corresponding to F+ and F color centers, respectively.
Crystallization Behavior of a New Transparent Glass-Ceramics
Authors: Wang Shu Ming , Kuang Feng Hua , Yan Qing Zhi , Zhang Qing Chun , Ge Chang Chun
Published: April 2010

In this article we present a new kind of large grain transparent glass-ceramics obtained by the method of crystal growth from a homogenous glass, the simultaneous variation of the glass matrix and crystalline compositions during the crystallization results in the high transparency of this kind of large grain, high crystalline volume glass-ceramics, which have suitable refractive indexes between respective phases. The nucleation and crystallization behaviors of this kind of glass-ceramics have been investigated. The optimum heat treatment schedule for the glass was determined by means of DSC, XRD and SEM. The desirable optical property, such as laser characteristics etc, of this new kind of glass-ceramics can be further developed by doping with transition metals or rare-earths.
Preparation of Foam Glass Ceramics from Phosphorus Slag
Authors: Xu Ben , Liang Kai Ming , Cao J.W. , Li Y.H.
Published: April 2010

Phosphorus slag could be used to prepare wollastonite glass ceramics. With the aid of incorporated foaming agent, foam glass ceramics can be obtained via the sintering of the slag-based glass. After the glass powder reacted with graphite, macro-size pores with homogeneous distribution were formed. The level of porosity of the fabricated foams was controlled by varying heat treatment temperature and amount of foaming agent. It was found that the preferential processing parameters for producing foam glass ceramics were foaming temperature of 1000°C with holding time of 10 min and 1 wt. % of graphite. In this case, the porosity reached about 80%. The results show that dominant crystalline phase is wollastonite, and the high compression strength results from the crystallization of glass during sintering process.
Effect of Pore-Forming Processing on the Gas Permeability and Flexural Strength of Porous SiC Ceramics
Authors: Fan Lei , Wang Hong Jie , Jin Zhi Hao
Published: April 2010

The porous SiC ceramics were prepared by two methods of pore-forming. The gas permeability and flexural strength of the porous SiC ceramics prepared by different ways were investigated. The porous SiC ceramics prepared by particle stacking have evenly pore distrubution; the gas permeability was greatly increased with the particle size increasing while the porous SiC ceramics were kept a higher flexural strength. The pore-former also can be used to form large pores to increase the gas permieability. However, these unevenly distribution large pores lead to a deterioration in flexural strength.