bluuebunny/crossref_metadata_2025 huggingface dataset:
Li2O-Al2O3-SiO2 Glass-Ceramics Used As Anodic Bonding Materials
Authors: Li Hong , Du Yun , Cheng Jin Shu , Wang Tian He
Published: March 2009

The glass-ceramics, whose coefficient of thermal expansion approximately matched to that of
silicon, were studied to replace conventional heat-resistant glass as substrate material for anodic bonding.
The basic glasses of the Li2O-Al2O3-SiO2 system with TiO2 and ZrO2 as nucleation agents were prepared
by melting technology, and the temperatures of nucleation and crystallization were determined. The
glass-ceramics were obtained by two-step heat-treatment method. The oriented crystallization of glasses
in gradient temperature field was studied. The crystal phases and microstructures of glass- ceramics were
analyzed. Effect of heat-treatment schedule on the coefficient of thermal expansion was discussed. The
results showed that the most of the main crystal phases of the samples were β-spodumene. The coefficient
of thermal expansion of sample was about 32.5×10-7/°C, which was approach to that of silicon.
Sterilization of E. Coli by Fe-Doped TiO2 Modified Photocatalytic Paint under Visible Light Irradiation
Authors: He Rong Liang , Wei Yi , Cao Wen Bin
Published: March 2009

Photocatalytic paint was prepared by adding Fe-doped TiO2 nanocrystalline powders into
self-engineered oxidation-resistant latex paint system. The UV-Vis diffuse reflectance spectroscopy was
used to characterize the light absorption properties of the paint. The colony counting method was used to
study photocatalytic sterilization ratio of E. coli under visible light irradiation. Effects of the kinds and
amounts of TiO2 powders added in the paint on the sterilization ratio under visible light irradiation with
fixed relative humidity were systematically investigated. The UV-Vis diffuse reflectance spectroscopy
indicates that the absorption thresholds of the Fe-doped TiO2 paint have red-shifted into visible light
region. The antibacterial experiment results show that the sterilization ratio of E. coli can exceed more
than 99% in less than 4 hours under 400-lux-visible light irradiation under RH of 55%.
Preparation of Molybdates with Antibacterial Property
Authors: Meng Yan Yan , Xiong Zhao Xian
Published: March 2009

A series of molybdates, Ag2Mo2O7 and AMoO4 (A = Zn, Co), were prepared as a new type of
inorganic antibacterial agent via wet chemical routes including hydrothermal synthesis and coprecipitation
reaction. The structure and morphology of the samples were characterized with X-ray diffraction
and scanning electron microscopy. The anti-bacterial properties of the molybdates against Escherichia
coli and staphylococcus aureus were examined, showing good antibacterial behavior.
Local Structures and Decomposed Phases of Laser-Melted ZrSiO4
Authors: Wang Wen Yan , Xie Jing Pei , Yan H. , Li Ji Wen , Li Luo Li , Hou Jin Ling
Published: March 2009

Behaviors of CO2 and pulsed YAG laser melting of ZrSiO4 have been investigated using
infrared (IR) spectroscopy. The laser-melted ZrSiO4 decomposed into binary oxides (ZrO2 and SiO2),
while other phases or complex ZrSiO4 tetrahedron networks are also observed. The local structures and
the phases of the quenched melts depend strongly on the quenching rate and melting conditions.
Monoclinic ZrO2 are found to be the main ZrO2 phase in the samples treated by CO2 laser, although
tetragonal ZrO2 was found near boundaries between the untreated and melted regions. High concentrations
of tetragonal ZrO2 were detected in the samples treated by pulsed YAG lasers. Observations indicate
that the formation of tetragonal ZrO2 is related to relatively high quench rates. Micro-IR data from areas
near the boundaries between the quenched melts and untreated zircon show systematic variations of local
structures and compositions. A small region with relatively low density between the untreated and melted
boundaries was observed, which consists of tetragonal ZrO2 or glassy ZrO2, and SiO2. Broad vibrational
bands occur in the wave number region where the characteristic frequencies of zircon are located. This
observation could indicate the possible existence of small amounts of glassy ZrSiO4 in the melt state of
zircon, although zircon tends to decompose above the melting point.
Analysis of Mechanisms of Spark-Plasma Sintering
Authors: Olevsky Eugene , Kandukuri S. , Froyen Ludo
Published: March 2009

Spark-Plasma Sintering (SPS) involves rapid heating of powder by electric current with
simultaneous application of external pressure. Numerous experimental investigations point to the ability
of SPS to render highly-dense powder products with the potential of grain size retention. The latter ability
is of significance for the consolidation of nano-powder materials where the grain growth is one of the
major problems. A model for spark-plasma sintering taking into consideration various mechanisms of
material transport is developed. The results of modeling agree satisfactorily with the experimental data in
terms of SPS shrinkage kinetics.
Preparation and Characterization of Citrate Sol-Gel Derived CaLa4Ti4O15 Microwave Dielectric Ceramics
Authors: Pei Jing , Yue Zhen Xing , Zhao Fei , Li Wei , Gui Zhi Lun , Li Long Tu
Published: March 2009

In this work hexagonal perovskite powders of CaLa4Ti4O15 were prepared by citrate sol-gel method. The calcined temperature was 1150oC, which is lower than that of the conventional solid method. Dense CLT ceramics were produced at sintering temperature of 1600oC. The crystal structures and microstructures were investigated by XRD, TEM and SEM, respectively. Compared with samples produced by solid method, the sol-gel derived CLT ceramics exhibited a near zero temperature coefficient of resonant frequency (τf ) of -6 ppm/oC, and other microwave properties , εr ~ 43, Q×f ~ 42000 GHz were also obtained. Moreover, the sintering temperature of the CLT ceramics could be reduced to 1400 oC by addition of B2O3-ZnO.
Monte-Carlo Simulation for the Grain Growth of Si3N4 during Sintering Process
Authors: Zhao Yu Hong , Zhang Yue , Zhang Da Hai
Published: March 2009

Based on the Potts model, the grain growth of Si3N4 in liquid phase sintering process was
simulated by Monte-Carlo method. A two-dimensional, square lattice is used to digitize the microstructure
and the components and grain orientation are distributed randomly. The periodical boundary
condition is applied. In the initial simulation, the grain growth and coarsening process driven by the
reduction in interfacial free energy within a complex system involving a liquid phase were investigated
with 32 orientations and different fraction of a liquid phase has been considered. Simulation was carried
out with 200×200 lattice. The effects of the liquid amount on the grain growth mechanism and
microstructures were discussed.
Mechanical Properties Evaluation of Ultra-High Temperature Ceramics
Authors: Bu Xiao Xue , Bao Yi Wang
Published: March 2009

Ultra-high temperature ceramics (UHTCs) have attracted increasing attention of material
scientists and engineers due to their promising application in reactive atmospheres such as monatomic
oxygen at high temperatures over 1600°C. However, the mechanical properties of this kind of ceramics at
ultra-high temperature are difficult to measure because of the temperature limits of the furnace and
fixture. In this work, an innovative measuring approach, trace analysis method, is presented for estimating
the ultra-high temperature mechanical properties. Various material parameters, including elastic
modulus, hardness, recovery deformation and energy dissipation capacity at ultra-high temperature could
be determined via a residual indent trace that was induced by a fast impact of a ceramic conical indenter
on the local area at high temperature.
Preparation and Characterization of Multilayered Mullite/Mo Functionally Gradient Materials
Authors: Chen Shu Heng , Wang Lin Jiang , Xie Xiang Li , Zhang Ye
Published: March 2009

Multilayered mullite/Mo cermet functionally gradient material (FGM) was fabricated through
a powder stacking process and sintering in vacuum up to 1500°C. The composition distribution, microstructure
and microhardness of the FGM were analyzed. The results indicated that the mullite/Mo FGM
was well densified with composite graded distribution and there was no new phase appeared. The microhardness
of the FGM increase from 467HV to 1543HV, the density from 2.919 to 7.106 g/cm3 as the
content of mullite increase from 20% to 80%. The relative density exceeded 90% as the content of mullite
reached 80%. Thermal shock test showed that the cracks passed through the joint without deflection.
Temperature Dependence of Raman Spectrum of Lead-Free Piezoelectric (Na0.5K0.5)NbO3-LiNbO3 Ceramics
Authors: Hotta Tatsuro , Kakimoto Kenichi , Ohsato Hitoshi
Published: March 2009

(Na0.5K0.5)NbO3-LiNbO3 (LNKN) is a lead-free ceramics, reported to show the maximum
piezoelectric property when the Li content is 6.0 mol%. The temperature dependence of the spectra was
measured for LNKN in the 4.0-8.0 mol% range of Li content by using Raman scattering. The stretching
and bending mode of NbO6 octahedron especially changed the form and/or frequency of the spectrum
with increasing Li content from 5.0 to 6.0 mol%. The range of this composition is corresponding to the
composition with the maximum piezoelectric property.
Preparation and Characterization of Relaxor-Based Ferroelectric Thick Films with Single Perovskite Structure
Authors: Fan Hui Qing , Chen Jin , Chen Xiu Li
Published: March 2009

Lead magnesium niobate-lead titanate (0.8Pb(Mg1/3Nb2/3)O3-0.2PbTiO3, PMN-PT) thick films in the thickness range about 75 μm have been successfully fabricated on Au-coated Al2O3 substrates by electrophoretic deposition (EPD). Non-aqueous colloidal suspensions suitable for EPD were prepared by mixing ultrasonically PMN-PT particles in ethanol with pH=6.0. The effect of EPD process parameters such as deposition voltage, deposition time and the specific deposition mass of PMN-PT particles were investigated. The EPD parameters were optimized in order to obtain crack-free, high-quality uniform ceramic films. The deposited pyrochlore-free PMN-PT thick films were sintered at 1000oC for 30 min, and the phase evolvement and the microstructure of the film were characterized by X-ray diffraction and scanning electron microscope.
Effect of Heating Time on the Structural and Electrochemical Properties of LiFePO4 by Molten Salt Method
Authors: Zou Zheng Guang , Li Xiao Min , Wu Yi , Long Fei , Yao Dong Ye
Published: March 2009

Well-crystallized LiFePO4 cathode materials were synthesized by NaCl-KCl molten salt
method. The effect of heating time on the structure, morphology and electrochemical properties of the
materials were studied in detail. Single olivine-type LiFePO4 phase was obtained, and the morphology
and particle size of the powders could be controlled by changing the synthesis conditions. It was shown
that LiFePO4 cathode material synthesized at 680°C for 3h with the salt content N=2 (defining the molar
ratio of NaCl-KCl/LiFePO4 as N) had a narrow particle-size distribution and spherical or quasi-spherical
shape. Meanwhile, the tap density of the cathode material reached the maximum of 1.501gcm-3. The
charge-discharge test indicated that the initial charge and discharge specific capacity reached 138mAhg-1
and 125mAhg-1 respectively at the current density of 0.3mAcm-2.
Effect of Doping Mode on the Photoluminescence Property of CaS:Eu Phosphor
Authors: Xia Yu Juan , Liu Wei Feng , Huang Fu Qiang , Wang Wen Deng , Lin Xin Ping , Liu Min Ling , Shi Jian Lin
Published: March 2009

Eu-doped CaS phosphors were prepared from sulfurization of CaCO3 in H2S gas without flux. The doping of Eu activator was conducted in two different modes: synchronous doping during sulfurization of CaCO3 and subsequent doping by vacuumly calcinning pure CaS and Eu2O3. Comparison of the as-prepared samples indicated that subsequent doping led to larger optimum Eu concentration and lower red emission intensity than synchronous doping. The different luminescence properties are ascribed to the different activator distributions in CaS host induced by different doping modes, and the uniform distribution resulted from synchronous doping is beneficial to the luminescence of the phosphor.
Enhancement of Blue Emission via Upconversion in Solid-State Synthesized Hexagonal NaYF4:Ln3+
Authors: Wu You Na , Cheng Chang Hua , Xiong Zhao Xian
Published: March 2009

Hexagonal NaYF4:Ln3+ (Ln3+=Yb3+ and Tm3+) was prepared via solid-state synthesis route. The synthesized powders were identified with X-ray diffraction patterns. Hexagonal phase was obtained by heating the powders at 550°C in reducing atmosphere, and the ions of Yb3+ and Tm3+ were completely incorporated into the lattice of hexagonal NaYF4 in the doping concentration range. Microstructure of the phosphor was observed by scanning electron microscopy (SEM). Intense blue (1G4→3H6, 1D2→3F4) and weak red (1G4→3F4) upconversion emission of Tm3+ ions with the energy transferred from Yb3+ ions were observed in the phosphor excited with a 980nm continuous wave laser diode. The intensity of blue emission was effectively enhanced by suitable doping of Tm3+ and Yb3+ ions, and strongest blue emission was obtained with the concentration of 0.2mol% Tm3+ and 40mol% Yb3+ doped.
Liquid Phase Sintering of Barium Titanate Ceramics for High Energy Density Capacitors
Authors: Huang Jia Jia , Zhang Yong
Published: March 2009

Several glass compositions with high electrical resistivity were developed and added to the
barium titanate ceramics. The glass additions were found to greatly increase the breakdown strength of
the composite ceramics which has a 0-3 connectivity. The electrical properties of the liquid phase sintered
ceramics are sensitive to the variations of the volume fraction and connectivity of the glass phase.
Corrective Effect of Average Grain Size on Grain Boundary Number of ZnO Varistors
Authors: Tu You Ping , Luo Feng Chao , He Jin Liang , Hu Jun
Published: March 2009

The average intercept length and related corrective method are proposed to calculate the
average grain boundary number. The average value of barrier voltage by direct measurement to single
grain boundary is 3.3V in literatures, but from our prepared ZnO varistor samples, the value of the average
barrier voltage by the average grain size is only 2.3 V. It is in the range from 3.24 to 3.38 V by the
proposed method, which is very close to the direct measured value 3.3V of the single grain boundary. The
introduced method to calculate average grain size has an obvious effect to correct the calculated barrier
voltage to near the actual one by direct measurement to single grain boundary.
Effect of B2O3 Doping on the Microstructure and Electrical Properties of ZnO-Based Varistors
Authors: Liu Feng Hua , Xu Gao Jie , Duan Lei , Li Ya Li , Cui Ping
Published: March 2009

B2O3 doped ZnO-Bi2O3-Sb2O3-based varistors were fabricated by conventional solid state reaction method. The structure and electrical properties were investigated by XRD, SEM and electrical measurements. The grain size obviously increases with increasing B2O3 content, while the content of Zn7Sb2O12 spinel on the grain boundaries gradually decreases, which implies that B2O3 doping inhibits the growth of Zn7Sb2O12 spinel. The density (ρ) of ZnO varistors increases with increasing B2O3 content (x) and reaches the maximum at x = 0.4 mol%. The sample with x ≈ 0.6 mol% sintered at 1150 °C exhibits the best performance, with nonlinear coefficient of 48 and leakage current of 4 μA.
Influences of Dopants on the Microstructural Nonuniformity of ZnO Varistors
Authors: He Jin Liang , Hu Jun , Luo Feng Chao
Published: March 2009

This paper systematically analyzes the microstructural nonuniformity of ZnO varistors when
Al2O3 dopants are added. The introduction of Al2O3 dopants leads to a decrease of ZnO grain growth rate
and correspondingly an increase of the microstructural uniformity of ZnO varistors. Both the average
value and the standard deviation of ZnO grain sizes decrease with the increase of Al2O3 content,
approximately in a log-linear relation. With detailed experimental results, this study provides quantitative
references for the practice of adding Al2O3 dopants to give ZnO varistors desired microstructural and
electrical characteristics.
XPS Research on SrTiO3-Based Voltage-Sensitive Material
Authors: Xu Yu Xing , Tang Zi Long , Zhang Zhong Tai
Published: March 2009

SrTiO3-based voltage-sensitive material was prepared successfully. The structure and
properties were investigated using scanning electron microscopy, X-ray diffraction and X-ray
photoelectron spectroscopy. It was observed that the average grain size was greater than 3μm and a cubic
perovskite structure was obtained. XPS analysis of oxygen indicated that there existed multiform
chemical state oxygen at the surface of the grain. Further researches shown that there were a few [AO12]
polyhedrons and many cation vacancies in the material discussed, which demonstrated that a lot of
oxygen volatilized and a well-known semiconductivity level was achieved.
Effect of the Combination of HTR and NTR Processes on the Magnetic Properties of Strontium Hexaferrite
Authors: Seyyed Ebrahimi S.A.
Published: March 2009

Hydrogen treatment and re-calcination (HTR) and nitrogen treatment and re-calcination (NTR) processes have marked effects on enhancement of the magnetic properties , particularly coercivity, of the strontium hexaferrite powder synthesized conventionally. This improvement is mainly attributed to finer structure obtaining after gas treatment. In this work, the effects of different combinations of these processes on the powder and bulk magnetic properties have been studied by using VSM and Permeameter. XRD and SEM techniques have also been used for characterization of the processes.
Field Emission Characteristics of Orthorhombic Boron Nitride Films
Authors: Li Wei Qing , Zhao Yong Nian
Published: March 2009

Orthorhombic boron nitride (o-BN) films with various thickness (150, 220 and 300nm etc.) are
prepared on Si(100) substrate by radio frequency plasma enhanced pulsed (Nd:YAG) laser deposition
(RF-PEPLD) in Ar-N2 gas system. The films are characterized by Fourier transform infrared spectroscopy
and atomic force microscopic. The field emission characteristics of the BN thin films are measured in an
ultrahigh vacuum system. A threshold electric field of 8V /6m and the highest emission current density of
157.5mA/cm2 at an electric field of 20V/6m are obtained for the 150nm-thick BN film and a threshold
electric field of 18V / 6m and the highest emission current density of 332.9mA/cm2 at an electric field of
52 V/6m are obtained for the 220nm-thick BN film. The results show that the threshold electric field
increases with increasing thickness of the films, while the withstand voltage characteristic of the BN films
also increases with increasing thickness of the films. The Fowler-Nordheim plots show that electrons
emitted from BN to vacuum by tunneling through the potential barrier at the surface of BN thin films.
Formation of Regular Hexagonal Dislocation Network in Chemical-Furnace Sintered Alumina
Authors: Meng Fan Cheng , Fu Zheng Yi , Wang Wei Min , Zhang Qing Jie
Published: March 2009

Polycrystalline alumina was prepared at high temperature and high pressure from combustion
reaction plus mechanical pressure. The defect structure in the sintered alumina was investigated by
transmission electron microscopy and a regular hexagonal dislocation network was found. Diffraction
contrast technique revealed that the regular hexagonal network on the (0001) plane was composed of
three dislocations with Burgers vectors: 1/3[1210], 1/3[ 2110] and 1/3[1120]. The formation process of
dislocation network was discussed.
Rheological Behavior of Modified Starch-Alumina Oxide Suspensions
Authors: Huang Yun , Chen Ling , Ye Jian Dong , Li Xiao Xi , Zhang Xi Mei , Ju Chen Hui
Published: March 2009

A modified starch was employed to be the pore former in the in-situ consolidation forming
process of porous alumina ceramic. In order to prepare ceramic slurry with high dispersion, high
stabilization and high solid volume loading, the effects of modified starch content, dispersant content,
alumina solid volume loading, pH value of the slurry and ball milling time on the rheological behavior of
alumina ceramic slurry were investigated. The results indicated that the viscosity of the slurry increased
with the modified starch content, alumina solid volume loading and ball milling time. When the pH value
of the slurry was 9.0, the modified starch-alumina slurry exhibited high fluidity. The modified
starch-alumina slurry was a pseudoplastic fluid exhibiting shear thinning behavior. The slurry possessed a
desirable plasticity to enable shape forming when adding 50 vol% modified starch and 1.0 wt% dispersant
to the alumina slurry at pH 9.0 after 14 h ball milling treatment.
On the Sintering Activation Energy of α-Al2O3
Authors: Shao Wei Quan , Chen Shaou , Li Da , Qi Ping , Wan Yong , Zhang Yong Cheng
Published: March 2009

The sintering activation energy of high-purity alumina powders with different particle sizes was evaluated under non-isothermal condition. It was found that, during sintering, the activation energy for the lower temperature stage is higher than that for higher temperature stage. The value of the activation energies for the powder compact with larger particle size was higher than that for the powder compact with smaller particle size. If the selected temperature interval for calculation was narrow enough, the evaluated activation energy values varied with the increasing temperature continuously.
Synthesis Processes of Nano Alumina Abrasive
Authors: Li Zi Cheng , Li Zhi Hong , Zhang Ai Ju , Zhu Yu Mei
Published: March 2009

Synthesis processes of nano alumina abrasive precursor using precipitation method and sol-gel method were investigated in this study. Using pressureless sintering, the nano alumina abrasive was prepared. Mechanical properties of the samples were measured by using single particle compressive strength tester. The microstructures of them were examined by using field emission scanning electron microscopy (FESEM). The results indicated that the performance and microstructure of the samples are greatly relative to the synthesis processes. Compared with samples prepared by precipitation method, the samples prepared by sol-gel method have higher compressive strength, smaller grain size and more uniform microstructure. The average grain size of the alumina abrasive was below 100nm.
Effects of Mn Doping on Dielectric Properties of BSTN Ceramics
Authors: Cheng Xin , Zhou Zong Hui
Published: March 2009

The effects of Mn doping on the phase composition and dielectric properties of
(1-x)BaO·xSrO·0.7TiO2·0.3Nb2O5 (BSTN) composite ceramics was investigated. The results showed
that the dielectric constants of 0.7BaO·0.3SrO·(0.7-z)TiO2·0.3Nb2O5·zMnO2 (BSTNM) composite
ceramics basically decreases as the content of doped MnO2 increases at the same applied frequency, while
tanδ decreases when value z≤0.01 but increases when value z>0.01. The phase transition temperature of
tungsten bronze phase in BSTNM composite ceramics increases with the increase of value z.
Phase Composition, Mechanical and Thermal Properties of (MgO)0.1-x(YO1.5)x(ZrO2)0.9 and (MgO)0.1-x(CaO)x(ZrO2)0.9 Ceramics
Authors: Fan Chuan Gang , Xu Lan , Yan Jie Rong , Zheng Cui Hong , Li Jia Mao
Published: March 2009

(MgO)0.1-x(YO1.5)x(ZrO2)0.9 (MYZ) and (MgO)0.1-x(CaO)x(ZrO2)0.9 (MCZ) ceramics were
prepared and their phase composition, bulk density, flexural strength, and thermal shock resistance were
characterized. There was an abrupt change of c/(c+m) from 29% to 75% as 0<x<0.01 for MYZ, and a
change of c/(c+m) from 42% to 88% appeared as 0.02<x<0.03 for MCZ (the c and m representing the
content of the cubic and the monoclinic phases respectively). When x=0.01~0.05, the resulting MYZ
specimens had the resembling c/(c+m) at about 75%, and a thermal shock resistance of more than 5 times
(1100oC⇔25oC) appeared for x=0.03~0.05 specimens. However for MCZ, only specimen of x=0.01
with c/(c+m) of 33% had a thermal shock resistance more than 5 times.
Preparation and Characterization of Zirconia-Based Multi-Phase Nanocomposite
Authors: Yang Yong Shun , Liu Yi Ran , Chen Guo Qing
Published: March 2009

ZrO2 (3Y)-CaO-SiO2-TiO2 powders with excellent chemical homogeneity were synthesized by
heating the alcohol-aqueous salt solutions. The powders have good dispersion, with particle size of
11~15nm and no hard agglomeration. The nanocomposite powders were hot-pressed in vacuum. The
obtained zirconia-based multi-phase nanocomposites were characterized by using XRD and SEM, as well
as relative density testing. The results demonstrated that, even though the sintering temperature was as
low as 1250°C, a high relative density of 97.5% was achieved. The superplastic compressive tests of the
as-sintered specimens demonstrate that this material behaves good deformability at 1350~1500°C, at
which the maximum extrusion pressure is lower than 35MPa.
Preparation of RBSC Green Bodies by Gel-Casting
Authors: Liu Hai Lin , Chen Yu Feng , Wang Hua , Tang Jie
Published: March 2009

In this paper, green bodies of RBSC were prepared through the gel-casting process. The effects
of monomer concentration and ratio of MBAM to AM on the strength and microstructure of the green
bodies were studied. When the monomer content increased from 10wt% to 20wt %( relative to water in
the slurry), the flexural strength increases efficiency. However, the flexural strength decreases when the
monomer content was above 20wt%. Similarly, when the ratio of MBAM to AM increased from 1/19 to
1/9, it had the same effects on the flexural strength of green bodies. It was found that silicon carbide
particles were packaged by the carbon particles with gel. When the monomer content was 20wt% and the
ratio of MBAM to AM was 1/9, the green body showed the best homogeneous microstructures and its
flexural strength achieved 8MPa.
Electrical Characteristics and Microstructures of (Gd, Dy)-Doped Bi4Ti3O12 Ceramics
Authors: Cai Y.H. , Mei X.A. , Chen Min , Su K.L. , An W.K. , Liu J.
Published: March 2009

The electrical properties of Bi3.25Dy0.75Ti3O12 (BDT) and Bi3.25Gd0.75Ti3O12 (BGT) ceramics were investigated. The current-voltage curve of the BGT sample exhibits a negative differential resistance behavior, whereas that of the BDT sample exhibits a simple ohmic behavior. The impedance spectrum of the BDT and BGT samples indicate that both consist of semiconducting grain and moderately insulating grain boundary regions. XRD, SEM and EPMA analyses reveal crystalline phase characterized by a Bi-layered perovskite structure of Bi4Ti3O12 and the distribution of every element is uniform. Both BDT and BGT samples exhibit randomly oriented and plate-like morphology.
Oxidation and Corrosion of Silicon Nitride at 1200°C and 1500°C
Authors: Blugan Gurdial , Wittig Daniela , Zinz Sieglinde , Graule Thomas , Kübler Jakob
Published: March 2009

The effect of different sintering additives on the high temperature oxidation and corrosion
behaviour of Si3N4 ceramics is investigated. A corrosion furnace was set up which allows testing of
ceramic discs at test temperatures upto 1500°C. It was possible to conduct tests under ambient oxygen
conditions, or with increased water vapour as well as testing with corrosive gases such as HCl or SO2.
Si3N4 was prepared with MgO, Al2O3, Y2O3 and Al2O3+Y2O3 sintering additives. These discs were
subjected to different oxidation and corrosion test conditions at temperatures of 1200°C and 1500°C for
upto 128 h. The effects that the different corrosion enviroments have on the corrosion resistance of the
Si3N4 materials are presented.
Ablation Performance and Surface Texture of the Nitride Composites Reinforced by the Braided Silica Fibers
Authors: Jiang Yong Gang , Zhang Chang Rui , Cao Feng , Wang Si Qing , Li Bin
Published: March 2009

Braided silica fibers reinforced nitride composite (SFRN), which was prepared by the polymeric precursor infiltration and pyrolysis (PIP) process with the precursor polyborosilazane (PSBZ), was a new typed microwave transparent material with high mechanical and ablation resistance performance for high-temperature application. The thermal ablation performance of the SFRN was evaluated by the ablation equipment with the kerosene and liquid oxygen as the heating source. The ablation surface texture of the SFRN including macrostructure and roughness were measured by Three-dimensional Macrostructure and Contour Scale System (TMCSS). Results showed that there are no concurrent observation of thermal delaminations or cracks and the specimen remains intact. The SFRN has an excellent thermal shock resistance and good ablation resistance with the linear recession rate of 0.038mm/s. The ablation surface texture of the SFRN can be well illuminated by the TMCSS. And the ablation performance will be improved by enhancing material density and homogeneous intertextures.
RIBAD Deposition of TiN on Magnesium Alloy
Authors: Abela Stephen , Grech Maurice
Published: March 2009

TiN coatings were produced by depositing a series of Ti layers and subsequently ion
implanting 80 keV nitrogen ions. TRIDYN FZR software simulation was used to estimate the
maximum Ti layer thickness which could be successfully transformed to TiN by ion implantation.
The chemical profile of these coatings was achieved by conducting a series of EDS measurements
across coatings, sectioned at shallow angles. It was found that the structure of the RIBAD TiN films
produced changes significantly with the implanted nitrogen ion dose. Their hardness and wear
resistance were found to increase rapidly as the post implantation time was increased up to 230
minutes, reaching a maximum of 27GPa and 2.5x10-12 mm3m-1N-1 respectively. On the other hand,
the electrochemical corrosion resistance of TiN coated magnesium substrate was inferior to that of
the untreated substrate material. The results suggest that the coating developed is attractive as a
topcoat of a duplex coating; having as underlay a corrosion protective film. In a separate study, it
has been shown that such coatings could be ion beam sputtered titania or alumina.
Molecular Dynamics Studies on the Growth and Structural Properties of Hydrogenated DLC Films
Authors: Zhang Yu Jun , Dong Guang Neng , Mao Jun Hong , Xie You Bai
Published: March 2009

The novel frictional properties of hydrogenated DLC (Diamond-like Carbon) films have
been reported for nearly ten years. But up to now, researchers still haven’t known the exact
mechanism resulting in the super-low frictional performance of hydrogenated DLC films. Especially
they have little knowledge on the molecular configuration and structural properties of these kinds of
films. In this paper, CH3 radicals with different impact energies are selected as source species to
deposit DLC films on diamond (100) by molecular dynamics simulation. Results show hydrogenated
DLC films can be successfully obtained when impact energy is in an appropriate scope that is no less
than 20eV. The depositing processes involve impinging diamond surface and bonding procedure.
Some atoms, instead of bonding with substrate atoms, fly away from the diamond surface. Only
suitable impact energy can improve the growth of the film. Within 30eV to 60eV, the maximum
deposition ratio is attained. In addition, when carbon atoms act as the deposition sources, the
deposition ratio is relatively higher. Furthermore, the authors find that species with higher
concentration of carbon atoms in deposition sources lead to a better deposition rate. Carbon atoms are
more reactive than hydrogen atoms. Then the relative densities of DLC films are calculated. The
density curves indicate that the structures of the films vary obviously as the impact energy augments.
The average relative density is generally monotone increase with the increment of impact energy. The
hybridization of carbon atoms greatly affects the properties of hydrogenated DLC films. The
transition between sp2 and sp3 will result in the graphitization and reduce the frictional coefficient
when DLC films are used as tribo-pair in friction.
Effect of Plasma Sprayed Ceramic and Cermet Coatings on Wear-Out Failure of High Temperature Ball Valve
Authors: Liu Lin , Gu Bo Qin , Chen Ye
Published: March 2009

Three kinds of coating materials, namely Cr2O3 ceramic, Al2O3-TiO2 ceramic and WC-Co
cermet, were screened and sprayed on the surface of valve ball by plasma spraying technology, and
two kinds of brush plating materials, namely high speed nickel and nickel tungsten, were also
screened and brush plated on the surface of valve seat by electrical brush technology. The
microstructure and morphology of the plasma sprayed coatings were analyzed by means of scanning
electron microscopy. The tribological properties of the plasma sprayed coatings sliding against the
high speed nickel and nickel tungsten layers were investigated on a pin-on-disc friction and wear
tester. The microhardness, thermal shock property and bonding strength of the coatings were also
tested. The results indicate that the sealing pair composed of the valve ball with the plasma sprayed
coating of Al2O3-TiO2 and the valve seat with the brush plating layer of nickel tungsten has the best
combination property.
Structure of Alumina Layer on the Damage Resistance of Multilayered CVD Coating under Repeated Impact Loading
Authors: Zhu Xiao Dong , Dou Hai Lin , Ban Zhi Gang , Liu Yi Xiong , He Jia Wen
Published: March 2009

Repeated impact test is an appropriate way to evaluate coating properties of metal cutting
tools since the cyclic impact loading applied in the test simulates the interrupted cutting process. For
hard CVD coatings with multi-layered structure, the alumina is usually of the lowest toughness and
adhesion, and relatively easy to fail in the metal cutting. In the present paper, multilayered coatings
consisting medium temperature TiCN, Al2O3 and TiN were deposited by chemical vapor deposition
(CVD) on the tungsten carbide/cobalt substrate and evaluated using scratch adhesion test and repeated
impacted test. The phase structure of alumina layers are α or )κ as usually applied in cutting tools, and
the grain size for the α phase one is varied from one micron to four microns. The scratch and
indentation test results show that the alumina layer of κ phase is easy to remove under the quasi-static
loading, implying brittleness and low adhesion. The repeated impact test results reveal lower impact
resistance for the κ phase alumina, and only adhesive failure can be found, which differs to that of the
α phase one. The coarse grained α-Al2O3 layer shows similar adhesion compared to the fine grained
α- Al2O3 in scratch test. The failure mode of the coating with coarse grained α-Al2O3 layer in the
repeated impact test is primarily impact wear. No cohesive failure can be found at all load levels, and
this leads to higher impact life than that of the fine grain one. It was shown that the relatively low
adhesion of bottom TiCN layer may not affect the impact resistance.
Microstructure and Properties of Surface Coating for Cr12MoV Steel Treated by TD Salt-Bath Vanadizing Process
Authors: Yang Ming Bo , Tang Li Wen , Yang H. , Zhao Wei Lin
Published: March 2009

In the paper the microstructure and properties of surface coating for Cr12MoV steel
treated by TD (Thermal Diffusion) salt-bath vanadizing process are investigated. The research
results indicate that after treated by the TD salt-bath vanadizing at 1223K for 5h and followed by oil
quenching, and aged at 453K for 2h, the Cr12MoV steel could obtain a surface coating whose
thickness is about 11.4um. The coating is mainly composed of vanadium carbide, and its thickness
and microstructure are uniform and compact, respectively. At the same time, the coating obtained
exhibits super-high surface microhardness, 2586HV. Then the wear resistance property of
Cr12MoV steel is improved drastically. In addition, the research results reveal that the effect of TD
salt-bath vanadizing treatment on the surface roughness of Cr12MoV steel is not obvious.
Electrodeposited Ni/Al2O3 Composite Coating on NdFeB Permanent Magnets
Authors: Zhang Hui , Song Yong Wei , Song Zhen Lun
Published: March 2009

NdFeB permanent magnets are highly susceptible to corrosion in various environments. A
new composite coating electrodeposited on NdFeB magnets was investigated in this paper. The Ni
matrix film was firstly electrodeposited on NdFeB surface from watts nickel electrolyte, and then
Ni/Al2O3 composite coating was successively electrodeposited on the Ni film. The microstructures of
electrodeposited Ni coating and Ni/Al2O3 composite coating were observed by scanning electron
microscopy (SEM). The corrosion behavior of Ni coating and Ni/Al2O3 composite coating in 3.5wt%
NaC1 solution was studied by polarization curves and electrochemical impedance spectroscopy
(EIS). The results showed that the Ni coating and Ni/Al2O3 composite coating could both provide
adequate protection to NdFeB substrate. But the free corrosion potential of Ni/Al2O3 composite
coating was more positive and the passivation region was more obvious when compared with Ni
coating. Meantime, the capacitance loop diameter of Ni/Al2O3 composite coating was significantly
larger than that of Ni coating ,which suggested that the anticorrosion resistance of Ni/Al2O3
composite coating was better than electroplated Ni coating.
Anodic Alumina Oxide Template with Branched Structure Formed in Phosphoric Acid
Authors: Wang Hui , Wang H.W. , Zeng P.
Published: March 2009

Anodic alumina oxide (AAO) templates with multi-branched structure were fabricated in a
phosphoric acid. Atomic force microscope (AFM) was utilized to investigate the unstable growth of
porous oxide film in initial stage. The morphologies of cross-section of AAO templates at different
current density were also studied with FESEM. The results show that the acquired AAO templates are
of multi-branched structure with large size. The diameter of pores on outer surface ranges from 150 to
220 nm, and the width of branches from 100-120 nm. This structure can be due to the unstable growth
of AAO film in initial stage. Besides, the structure of AAO template is sensitive to the current density
and the order degree decreases with the increase of current density: at 1.0A/dm2, most of tubes are not
straight and some divided into two branches; at 2.0A/dm2, all tubes grow disorderly and form net-like
structure. In this electrolyte, different types of structure of AAO templates can be acquired by
adjusting current density, which may be used for the synthesis of new types of nanowires with
improved mechanical properties.
Study of Corrosion Performance of Electroless Ni-P Coating with Molybdenum Disulfide Nanoparticles
Authors: Hu Xian Guo , Cai Wen Ju , Wan Jiu Cong , Xu Yu Fu , Sun Xiao Jun
Published: March 2009

The electroless nickel-phosphor coatings containing molybdenum disulfide nanoparticles
were prepared and analyzed in this paper. The effects of incorporation of MoS2 into the Ni-P coating
on the morphology of the coating surface and corrosion properties were also studied. Corrosion tests
were conducted inside a salt spray box with NaCl solution (5.0 wt%). The corrosional surfaces were
studied and analyzed through optical microscope, X-ray spectrometer (XRD) and scanning electron
microscopy (SEM). The investigation on the relationship between heat-treatment and the corrosion
resistance of the coatings showed that the corrosion resistance of the composite coating became worse
because of the occurrence of transformation from non-crystalline to crystalline, and then increased the
metastable intergradation of the composite coating. Meanwhile, the experimental results also showed
that corrosion resistance of the coating containing MoS2 was higher than that of steel substrate. The
corrosion mechanism of the composite coatings was mainly ascribed to the formation of micro-cell
around the nanosized MoS2 particles, and the active ion like Cl- destroyed the surface film and
induced the corrosion towards the inside part of coating.
Microstructure and Properties of Brush Electroplated Nano-SiC-Al2O3/Ni Composite Coating
Authors: Yang Hua , Dong Shi Yun , Xu Bin Shi
Published: March 2009

This paper investigated the effect of nano-SiC particle on microstructure and
properties of brush electroplated nano-Al2O3/Ni composite coating. Three kinds of coatings,
such as pure nickel coating, nano-Al2O3/Ni composite coating and nano-SiC-Al2O3/Ni
composite coating, were fabricated on 1045 steel substrate. Before deposited, Zeta potential of
nano-particles in the solution was examined. The results show Zeta potential of the
nanoparticles in the nano-Al2O3/Ni electrolyte is negative, but that of the nanoparticles in
nano-SiC-Al2O3/Ni electrolyte is positive when the pH value of electrolyte is about 7.5. Energy
dispersive spectroscopy (EDS) results show Al element content in the nano-Al2O3/Ni coating is
5.65%, while the content of Al and Si elements in nano-SiC-Al2O3/Ni coating is 5.63% and
4.86% respectively. It confirms that nano-SiC particle co-deposited in the composite coating
while nano-Al2O3 particle content keeps constant. The microhardness of nano-SiC-Al2O3/Ni
coating exhibits the highest, while the pure nickel coating is the lowest. And surface
morphology of nano-SiC-Al2O3/Ni coating is the most smooth and compact among the three
coatings. The wear test results reveal that wear resistance of nano-SiC-Al2O3/Ni coating is 1.7
times of that of nano-Al2O3/Ni coating, and 2.3 times of that of pure nickel coating. The above
results show the nano-SiC particle services a strengthening effect on the combination
performance of nano-SiC-Al2O3/Ni coating.
Microstructure and Abrasion Resistance Mechanism of CrB Particles Reinforced MMC Coating
Authors: Deng Hua Ling , Li Guang Long , Song Yun Jing , Xiao Shi Rong
Published: March 2009

The CrB Particles Reinforced MMC Coating was prepared by using high velocity arc
spraying (HVAS) method. Through a series of experiments, including metallographic, SEM and
EPMA investigation, the microstructure and composition of the coating were analyzed in details.
Additionally, the abrasion resistance mechanism of the coating was studied through field test and
observation on the abrasion surface of the coating under the SEM. The results show that the
microstructure of the coating is characterized by typical compact laminated structure composed of
successive metal matrix and hard particles mainly of borides of chromium and oxides of chromium.
The abrasion resistance mechanism of the coating lies in two aspects. One is that the hard particles
scatter evenly and dispersedly in the coating, which can reinforce the coating and play a barrier role
to hinder the movement of the abrasion particles. The other is that the metal matrix with well
ductility and toughness make a buffer action to the impact caused by the abrasion particles, thereby
the waste rate of the coating can be greatly slowed down. The results also show that the hardness,
shape and quantity of the reinforced particles have magnificent influence on the abrasion resistance
of the coating made in this paper.
Electrical Conducting Coating on Glass Substrate Deposited by Wire Exploding Spray Coating Method
Authors: Yang Jia Zhi , Liu Zhong Yang , Xu Dong Wei , Liu Tian Jie
Published: March 2009

An electrical conducting copper coating on the glass substrate is deposited by means of
wire exploding spray coating (WESC). The coating system basically consists of a high voltage pulsed
power supply and a coating chamber. A pulsed voltage is produced by the power supply upon the
metal wire in the coating chamber. The whole process is under taken at atmosphere pressure and room
temperature. The coating is more uniform when a higher discharging voltage is applied, which means
more energy is deposited into the copper wire in the identical time, so the wire will be destructed more
efficiently. A 20 kV discharging voltage is applied in this paper for the balance of coating quality and
harmless to the glass substrate.
The coating samples are analyzed by a series of tests. The SEM photograph shows that the copper
particles penetrate deeply into the glass substrate, which results in a strong adhesion of the coating,
and the thickness of the coating is about 400 to 500 μm after sprayed three times. The electrical
conductivity of the copper coating is about 1.837*104 1-1·m-1 tested by a Kelvin electric bridge, and
the 50 Hz withstand voltage of the glass tube before and after the spray coating is about 40 kV and 38
kV, respectively, with no obvious decrease.
Study on Wear Resistance of Plasma Sprayed Coating Remelted by Laser
Authors: Liu Y.J. , Wang Y.S. , Yang Xi Chen
Published: March 2009

In order to improve the wear resistance of the surface of thick copperplate, a coating of
alloy powder is produced on the surface of the thick copperplate with the method of laser remelting
plasma sprayed coating. The value simulation of temperature and the experimental results show that,
it is difficult to produce ferronickel coating with large area and crackfree on thick copperplate for
laser cladding technique. Using transsonic plasma heat spraying method to fix the alloy powder on the
surface of thick copperplate, a sprayed coating can be produced, which has certain adhesion strength
to the copperplate. In order to prevent crack produced in large area laser remelting coating, a method
with band-like and point-like remilting area at intervals of same distance has been taken. The surface
appearance and roughness of the coating produced by plasma spraying are compared with that of the
coating produced by plasma spraying and remelted by laser, micro organization analysis and wear
resistance comparison experiments are taken to the specimen. The microstructure photos show that
the coating of the plasma heat sprayed is mainly made up by grains, with a great deal of pores existing.
After laser remelting, microstructure of the coating is more compact, and the most of pores
disappeared, so the strength of the boundary between the remelted coating and the copperplate is build
up and the coating with large area and crackfree on thick copperplate is performed by the method of
laser remelting plasma spraying coating in large amount of point-like remilting areas
The experiment result shows that the wear resistance of laser remelting plasma heat sprayed coating
enhances 3 times more than That of the unremelt coating, and about 14 times compared with the
copperplate, and the wear resistance of the surface with point-like laser remelting area is between that
of plasma heat sprayed coating and that of the laser remelting coating, it depends on the ratio of the
remelted part to the whole in area, however, the wear resistance increases with the value of the ratio
Tribological Behavior of Nano-Silicate Mineral Powder as Lubrication Oil Additive
Authors: Zhang Bo , Xu Bin Shi , Xu Yi , Wang Xiao Li , Zhao Yang
Published: March 2009

The tribological behavior and the mechanism of nano-silicate mineral powder as
lubrication oil additive were researched in the article. The tribological behavior of nano-silicate
mineral powder with mass ratio 0.6% in lubrication oil 50CC was tested and compared with the
lubrication oil 50CC’s by friction wear testing machine. The surface morphologies and elementary
compositions of grinding cracks were analyzed by Scanning Electron Microscope (SEM) and Energy
Dispersive Spectrometer (EDS).The results showed that the friction coefficient is decreased 37.5%,
and the lost mass of the upper proof sample reduces 68.75%, the down’s reduces 86.7%, after adding
nano-silicate mineral as lubrication oil additive, by comparison to lubrication oil 50CC’s. Under the
lubrication oil which has been putted nano-silicate mineral as additive, there is a repairing layer
whose material is different from basal body material on the grinding cracks; in addition, Si, Mg and
other elements are deposited on the repairing layer. These state that nano-silicate mineral as
lubrication oil additive possesses superior behavior of wear resistance, antiwear and self-repairing
effects.