bluuebunny/crossref_metadata_2025 huggingface dataset:
Diamond Coated on Cobalt-Deficient Gradient Tungsten Carbide
Authors: Gou Li , Zhu Ji Lei , Ran Jun Guo , Yan Suang Feng
Published: March 2009

In order to improve the adhesion between diamond coatings and cemented tungsten carbide (WC-Co) substrates, the diamond coatings were deposited on one kind of cobalt-deficient gradient WC-Co by the microwave plasma chemical vapor deposition (MPCVD). Scanning electron microscopy, X-ray diffraction and Raman spectroscopy were used to characterize the diamond coatings. The results showed dense, well facet diamond coatings. The cobalt content at the surface of
substrate was measured by electron probe microanalysis. It was found that Co did not largely move to the surface as usual with deposition time increasing compared with the conventional tungsten carbide; The cobalt content at the surface of substrate after deposition (about 1 wt %) was lower than before (3.42wt%), which improved diamond coating’s adhesion against the tungsten carbide substrate.
Enhancement of Photovoltaic Effect of PLZT Ceramics by Compositional Optimization and Grain Size Control
Authors: Cheng Da Ming , Li Jing Feng
Published: March 2009

Lead lanthanum zirconate titanate, PLZT ceramics have drawn great attention in
microactuation because the Photostrictive Effect in it. In this study, compositional dependence of photostrictive effect in PLZT was investigated. The factual compositions were configurated quantitatively by XRF to characterize the deviation in the preparation process. Different sintering periods were designed in an attempt to obtain PLZT ceramics with the same grain size but different compositions to explore the intrinsic photostrictive effect in the PLZT system. With this method, the
maximum intrinsic photocurrent was obtained at 3.48/50.7/49.3, while the maximum intrinsic photovoltage was obtained at 3.44/52.73/47.27.
Effect of La2O3 and CeO2 on Nb2O5 Doped TiO2 Ceramic Varistors
Authors: Mi Jia , Tang Zi Long , Luo Shao Hua , Zhang Zhong Tai
Published: March 2009

The influence of La2O3 and CeO2 on a new class of polystalline ceramics with electrical properties based on TiO2 was investigated. The content of added La and Ce is in 1 at%, while that of the other addition is always maintained at a constant value. The disks were sintered at 13800C for 4 hours. La2O3 was found to precipitate at the grain boundaries, probably inducing electronic interface
states that can trap charges at the TiO2-TiO2 interface and lead to significantly increase the nonlinear behavior. The values for α (» 4.2) and V1mA(» 26 V) support that finding. It was found CeO2 that as a dopant did not strongly influence the nonlinear values of the systems as did La2O3, indicating that it could have formed a solid-state solution with TiO2 in the grains, but did not segregate sufficiently at the grain boundaries. In present work, impedance analyzer, X-ray spectrometer, and scanning electron microscope (SEM) were used.
Study on Gas Sensing Properties of WO3 Thin Films
Authors: Jiang Miao , Hou Feng , Xu Ting Xian , Xu Ming Xia
Published: March 2009

Tungsten oxide thin films were prepared by an inorganic-sol-gel dip-coating process, where the sol was obtained by adding citric acid, as chelating agent, to the ammonia solution of tungstic acid. The resultant thin films were a mixture of monoclinic and tetragonal phases of WO3 and, after being pretreated at 600°C and sintered at 650°C, the average grain size of the polycrystalline films was about 500 nm. The gas-sensing properties of WO3 thin films were tested at temperatures ranging from 500° to 600°C and in nitrogen gas containing 5vol% O2 or 5vol% H2. The WO3 sensors exhibited a good sensitivity and response speed at the temperature of 550°C.
Low Cost Fabrication and Performance of YSZ Electrolyte Thin-Substrate
Authors: Chen Da Ming , Liu Xiao Guang , Tong Jian Feng , Li Bao Wei
Published: March 2009

A new technique for the fabrication of yttria stabilized zirconia (YSZ) substrates using aqueous gel-casting has been developed. This technique has been used to fabricate planar thin-substrate YSZ fuel cells. A thin-substrate YSZ electrolyte with high density and low porosity was prepared by this method with 57vol% solid content slurry. The character of the technique was discussed based on the influence of dispersant and pH value on slurry. After sintering, the YSZ electrolyte thickness is between 100 and 200µm, and the electrolyte area is 100 × 100 mm2. The research shows that aqueous gel-casting allows fabricate thin YSZ substrate with high density and homogenous structure. The method is suitable for preparing thin-substrate electrolyte of yttria stabilized zirconia.
The Control of the Reactions of Strontium Hexaferrite Formation by the Molar Ratio of Precursors
Authors: Seyyed Ebrahimi S.A.
Published: March 2009

Strontium hexaferrite is one of the very important categories of magnetic materials with a wide range applications. One of the very critical parameters in the high temperature method of production of this material is molar ratio of iron oxide to strontium oxide. Although there could be found some reports on the effect of this parameter on the physical properties of the material in the literature but there are very few investigations about the role of this factor on the reactions occurred in the process. In this work the effect of different molar ratios of precursors on the reactions carried out for processing of strontium hexaferrite have been investigated by using thermal analysis techniques such as DTA/TG. Furthermore, the microstructure and the powder and bulk magnetic properties of the products have been studied by SEM, VSM and permeameter.
Microwave Dielectric Properties of Mn-Doped Ba4.5Sm9Ti18O54 Ceramics
Authors: Xu Jian Mei , Zhou Dong Xiang , Zhang Dao Li , Huang Guo Hua , Gong Shu Ping
Published: March 2009

The different amounts of manganese dioxide were doped to Ba4.5Sm9Ti18O54 (BST)ceramics. It was found that the doping sequence of Mn had serious influences on the microwave dielectric properties of the BST ceramics. When manganese dioxide was added before the mixtures were calcined, the dielectric properties of ceramics were poor and decreased with the increase of the
Mn content. When the Mn content was between 2.0wt% and 3.0wt%, the BST ceramics had no microwave characteristic. But adding manganese dioxide in a range of 0.0 to 1.0wt% after the mixtures were calcined enhanced the microwave dielectric properties of the BST ceramics. When the Mn content changed from 0 to 1.0wt%, the microwave properties of the BST ceramics increased, but the microwave properties decreased while the Mn content was over 1.0wt%. The ceramics with 3.0wt% Mn content had also no microwave characteristic. The optimum microwave dielectric properties were as follows: εr=76, Q·f=7280,τf=-3.6ppm/k.
Synthesis and Luminescence Properties of Yb3+/Ho3+ Co-Doped Lu2O3 Nanocrystalline Powders
Authors: An Li Qiong , Zhang Jian , Liu Min , Wang Sheng Wu
Published: March 2009

Yb3+ and Ho3+ co-doped Lu2O3 nanocrystalline powders were synthesized by a reversestrike co-precipitation method. The as-prepared powders were examined by the X-ray diffraction and transmission electron microscopy. The phase composition of the powders was cubic and the particle size was in the range of 30~50 nm. Emission and excitation spectra of the powders were measured by a spectrofluorometer and the possible upconversion luminescence mechanism was also discussed.
Preparation and Characterization of a New Phosphor Lu2O3:Eu3+
Authors: Chen Qi Wei , Shi Ying , Shi Jian Lin
Published: March 2009

Europium-doped Lu2O3 nanocrystalline powders were prepared via a novel solution
combustion route, with glycine as the fuel. The crystalline size and specific surface area of the combustion derived powders are strongly dependent on the glycine-to-nitrate ratio, which can control the combustion flame temperature. XRD, SEM, TEM and BET were used to characterize the phosphors and the photoluminescence was also investigated. Lu2O3:Eu3+exhibits narrow-band red emission extending from 580-700nm with a sharp peak at 611nm, corresponding to 5D0→7F2 transition of the Eu3+ ion.
Preparation and Characterization of Ordered Macroporous ZnO Films for Photonic Application
Authors: Fu Ming , Zhou Ji , Zong Rui Long , Li Bo , Li Long Tu
Published: March 2009

Wide band-gap semiconductor ZnO film with ordered face-centered cubic (FCC)
structure air holes was prepared by electrochemical process. The porous ZnO film was prepared in
zinc nitrate aqueous solution, using the indium tin oxide (ITO) substrate covered with synthetic opals as cathode by potentiostatic method. In order to improve the filling ratio of ZnO in the opal interstices, various potentials were applied to control the deposition speeds. The porous ZnO film was characterized by X-ray diffraction and Scanning Electron Microscope and a photonic band gap at about 568nm was observed by micro-region reflection spectrometer in ZnO inverse opals.
Preparation of Nanocrystalline Ba3(Ca1.18Nb1.82)O9-δ Powder with Sol-Gel Auto-Ignition Synthesis Process
Authors: Su Xin Tai , Yan Qing Zhi , Ge Chang Chun
Published: March 2009

Ba3(Ca1.18Nb1.82)O9-d (BCN18) powder was synthesized using a wet chemical method from mixtures of all water-soluble compounds including Ba, Ca and Nb-citrate. It has been found that NH4NO3 in the initial solutions plays an important role in controlling the enthalpy of low temperature combustion process as well as the gel decomposition temperature. Further steps include evaporating,
drying and calcinating. The obtained gels were characterized by TG-DSC, and the powder was characterized with XRD, TEM and BET. The experimental results have indicated that the heating temperature was only 800°C for synthesizing the powder and the average particle size was only about 40-50 nm. Furthermore it was found that a pure BCN18 phase with complexperovskite structure was formed at 800°C, which was about 800°C lower than that of the traditional solid-reaction method. So
it is more practical and more superior to the traditional solid-reaction method and the present wet-chemical method in alcohol salt system reported in literature.
Converting Industrial TiO2 into Titanate Nanotubes by Simple Sonochemical-Hydrothermal Processing
Authors: Li Jun Rong , Tang Zi Long , Zhang Zhong Tai
Published: March 2009

Slim titanate naotubes was prepared from industrial coarse TiO2 powder by simple
sonochemical-hydrothermal processing. The influences of ultrasonic irradiation on TiO2 precursors were investigated. The morphology and crystal structure of the products were characterized by TEM and X-ray diffraction, respectively. The typical products are long nanotubes around 8-10nm in out diameter. Both anatase and rutile TiO2 precursors can be transferred into titanate nanotubes in this
sonochemical & hydrothermal processing.
Development of BaTiO3 Based X7R Wafers for Single-Layer Capacitors
Authors: Yu Zhengbo , Krstić Vladimir D. , Ng Jack
Published: March 2009

Research on the development and characterization of X7R BaTiO3 dielectric wafers for high frequency single-layer capacitors has been carried out. Commercial BaTiO3 powders were processed and optimized in dielectric constant (er), dissipation factor (DF) and temperature coefficient of capacitance (TCC). The results indicate a strong effect of sintering temperature on dielectric properties as well as on mechanical properties of the BaTiO3. It has been shown that the highest dielectric constant is achieved at high sintering temperatures (>1400°C) and lowest TCC at lower sintering temperatures (<1300°C). By optimizing fabrication process e.g. dry pressing, cold isostatic pressing, sintering, and machining such as
grinding and lapping, BaTiO3 wafers of dielectric constant from 3400 to 3600, with a diameter approximately 50mm and thickness 150µm, have been manufactured successfully. The fabricated thin wafers exhibit the X7R capacitor characteristics of the dissipation factor (<3%) and temperature coefficient of capacitance (<±15%) in the temperature range of –55°C to 125°C.
Preparation and Utilization of Fine Expanded Perlite
Authors: Sodeyama Kenichi , Sakka Yoshio
Published: March 2009

Hollow glass microspheres named expanded perlite have been prepared from perlite, but the size is usually above 20 µm. In the conventional preparation method, it is difficult to produce fine expanded perlite with particle size under 20 µm because the water contained in finely milled perlite particle, which is the origin of foaming, is evolved during heating process. A new fluidized sand-bedfurnace has developed and fine expanded perlite particles with particle size less than 15 µm and bulk
density under 0.5 g/cm3 are prepared successfully. Using the fine expanded perlite, lightweight composites with alumina and lightweight pottery are successfully prepared by colloidal processing and subsequent heating.
Effects of Rare-Earth Oxides on Dielectric Properties of X7R Ceramics for Base Metal Internal Electrode Capacitors
Authors: Chen Ren Zheng , Wang Xiao Hui , Zhao Jian Ling , Hao Jun Jie , Gui Zhi Lun , Li Long Tu , Zhang Li
Published: March 2009

The effect of rare earth oxides (Y2O3 and Dy2O3) on the microstructure and electrical properties of the X7R-type ceramics for base metal internal electrode multilayer ceramic capacitor (BME-MLCC) was investigated. As the amount of Y increased, the dielectric constants and the dielectric losses increased, while the temperature coefficient of capacitors (TCC) curve rotated in counterclockwise direction. On the contrary, the dielectric constants decreased with Dy, and the TCC
curve remained the same. The grain growth can be inhibited by the Dy2O3, concluded from XRD analysis. The different influences on dielectric properties between Y2O3 and Dy2O3 were discussed by defect chemistry. Y3+ acted as acceptor, performing B-site substitution, while Dy3+ showed the amphoteric behavior. By optimizing appropriate qualities of Y2O3 and Dy2O3, the most-compatible composition for BME X7R ceramics can be obtained.
Study of LSGM Slurry for Gel-Tape-Casting
Authors: Cheng Sheng , Gong Jiang Hong , Zhang Zhong Tai , Tang Zi Long
Published: March 2009

A novel process, gel-tape-casting, is employed to fabricate LSGM thin dense sheets in aqueous AM system. The influences of powder properties, dispersant and other additives were discussed and relevant processing parameters were also explored. The slurry of LSGM with a high solid loading about
33 vol.% was successfully obtained.
Co-Sintering of SDC / NiO-SDC Bi-Layers Prepared by Tape Casting
Authors: Li Hai Bin , Xia Chang Rong , Fan Xiao Hong , He Xi , Wei Xiaoliang , Meng Guang Yao
Published: March 2009

In the development of intermediate temperature solid oxide fuel cell (IT-SOFC), the anode supported thin electrolyte with higher conductivity than YSZ is an essential approach in recent years. In this work, we report our route that Ce0.8Sm0.2O1.9 (SDC) as electrolyte and porous NiO-SDC as anode substrate are prepared by a bi-layer tape casting and co-sintering process. The major effort was to adjust and control the shrinkage of the two material layers. It was found that only the specimens with less than 0.1% mismatching of the sintering shrinkage between two layers can result in the flat and crack free samples. In addition, high activity powders were the essential to obtain dense SDC electrolyte. Fuel cells with Sm0.5Sr0.5CoO3 as cathode were tested. The open circuit voltage (OCV)
and the power density of the cells confirmed the full densification of the SDC electrolyte on the anode support.
Influence of ZrO2 on Dielectric Properties of Ba1-xSrxTiO3 Ceramics
Authors: Xue Hao , Zhou He Ping , Ai Chen
Published: March 2009

Ba1-xSrxTiO3 ceramic (BST) was one of the promising materials applied in phased array antennas due to its excellent dielectric properties. Ba1-xSrxTiO3 ceramic was prepared by traditional solid state reactions. Effects of different amount of ZrO2 as additive upon the dielectric properties of BST were investigated. The analyzed results showed that, as the amount of ZrO2 increasing, the dielectric constant and temperature dependence of dielectric constant of this ceramic both decreased, while its dielectric tunability kept high value.
The Physical and Antibacterial Properties of Argentine-Doped TiO2 Film on Stainless Steel Substrate
Authors: Ding Xin Geng , Li Li
Published: March 2009

The aim of the present study is to investigate the physical properties and antibacterial performances of Ag+-doped TiO2 film on stainless steel and effects of surface oxidization. In the experiment, the surface of stainless steel was been oxidized by heat treatment (550°C, 1 hour) before the Ag+-doped TiO2 (anatase) film being formed by sol-gel method. Sample A (filmed after surface
oxidization), B (filmed without surface oxidization), C (only surface oxidization) and D (neither oxidized nor filmed) were respectively tested for corrosive resistance, abrasive resistance and adhesiveness, and the samples with different content of argentine was tested for antibacterial performance. Results: 1) Corrosion rates of sample A, B, C and D in 10% FeCl3 solution are respectively 1.65%, 1.87%, 2.02% and 3.28%, suggesting that the film has protected the stainless steel from the corrosion; 2) Scratching using a loaded (150 g) pin makes no crack on surface of sample A, while it results a slight scuffing on surface of sample B, suggesting that the surface oxidization has enhanced the abrasive resistance and adhesiveness of the TiO2 film, which may be due to the bridge-like function of the oxidation film; 3)Antibacterial performance is enhanced as the content of doping argentine increases, exceeding 90% when the argentine reached 3%, and the TiO2 film on the oxidized stainless steel performs better in antibacterial test than untreated one.
Study on Nano Film of TiO2 and ZnFe2O4 Composite Prepared by Dip Coating Method
Authors: Li Hong Yi , Ling Yun Han , Jiang Xing Jun , Bai Xin De
Published: March 2009

TiO2 is one kind of semiconductor-based photocatalyst. TiO2 shows relatively high reactivity and chemical stability under ultraviolet (UV) light. However TiO2 is poor absorber of photons in the solar spectrum. In order to improve the absorption efficiency, the coatings of TiO2/ZnFe2O4, ZnFe2O4and TiO2
on ITO were prepared by dip coating method, their microstructure, surface properties, photocurrent and photo absorption are investigated in this paper. XRD results show that the phases on the composite coatings are mainly TiO2 and ZnFe2O4 and the main phase on ZnFe2O4 and TiO2 coatings is ZnFe2O4 and
TiO2 respectively, the SEM results show that the coatings of TiO2 and TiO2/ZnFe2O4 are distributed evenly on the materials surface and the AFM results show that the grain size is about 20nm. The experimental results also show that the absorption wavelength of composite coatings of TiO2/ZnFe2O4 is 454nm, which is larger than that of TiO2 coatings (370nm). Under the irradiation of Xe lamp light, a
photocurrent of 27µA/cm2 on the materials surface could be obtained.
The Properties of Antimony-Doped Tin Oxide Thin Films by the Sol-Gel Approach
Authors: Zhao Lan , Zhang Dao Li , Du Gang , Xu Jian Mei , Zhou Dong Xiang
Published: March 2009

Antimony-doped tin oxide thin films have a range of technical applications as conductive coatings, and sol-gel processing seems to offer some advantages over other coating techniques. In this study, the sol was prepared by sol-gel approach from SnO2·H2O and SbCl3 in alcohol. It was found that the heat-treatment temperature and doping level have strong influences on the microstructure and
composition of Sb: SnO2 films. The SnO2 crystals exist mainly as tetragonal rutile structure. The optimum heat-treatment temperature is about 450 ~ 500°C, and the film is composed with nanocrystals and nano-pores. Microstructure and the electrical behaviors of Sb-doped SnO2 thin films derived by sol-gel process were investigated.
Preparation of SrBi2Ta2O9 Ferroelectric Thin Films by Liquid Source Misted Chemical Vapor Deposition Method Using Inorganic Salt Solution
Authors: Ji Hui Ming , Gu Yan Fei , Meng Hui , Xu Ting Xian
Published: March 2009

A liquid source misted chemical vapor deposition (LSMCVD) system was used to deposit SrBi2Ta2O9 ferroelectric thin films on Pt/TiO2/SiO2/Si substrates using strontium nitrate, bismuth nitrate and fluorine tantalum acid as the starting ingredients. Citric acid, ethylene glycol, and ethylenediaminetetraacctic
acid were employed as chelating agents to form homogeneous and stable sol. A density, homogenous, crack-free and c-axis oriented SrBi2Ta2O9 thin films were prepared successfully and the resultant thin film exhibits the ferroelectric properties of 2Pr of 3.8 C/cm2, 2Ec of 60kV/cm at ±3.5 V,
respectively.
Effect of Process Conditions on Stability of Ni-ZrO2 Composite Electroplating Bath
Authors: Huo Wei Rong , Liu Jia Chen , Qu Yuan Fang , Du Hai Yan
Published: March 2009

For the nano-ZrO2 powders, it is difficult to disperse the particles in a highly concentrated electrolyte. Polymer MZN with composite structure was employed as a dispersant in this work. On the basis of having obtained the optimum quantity of dispersant MZN, the effects of process conditions on stability of Ni-ZrO2 composite electroplating bath were investigated via sedimentation experiments and SEM micrograph. The results showed that the charging sequence have a significant
influence on the stability of composite electroplating bath, and the optimum process conditions is that the stable aqueous suspension of 2.5g nano-powders in 100 ml water should be prepared at first by milling for 3 hours, and then the electrolytes were added in it. The well-dispersed composite electroplating bath was obtained, which made sure that the nano-ZrO2 smaller than 30nm was found
in the Ni matrix.
Microstructure and Microwave Dielectric Properties of Ba5(Nb1-xTax)4O15 (x = 0 ~ 0.5) Ceramics
Authors: Zhao Fei , Yue Zhen Xing , Zhang Ying Chun , Gui Zhi Lun , Li Long Tu
Published: March 2009

The Ba5(Nb1-xTax)4O15 (x=0~0.5) solid-solution ceramics with hexagonal perovskite structure were prepared by solid-state oxide route. The phases and structure of the sintered ceramics were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of composition and sintering temperature on the bulk density, microstructure and microwave dielectric
properties were also investigated. As the value of x increased from 0 to 0.5, the Q×f value increases from 36,049 to 49,493 GHz (at ~9GHz), whereas the dielectric constant (εr) decreases from 39.21 to 33.03 and the temperature coefficient of resonant frequency (τf ) decreases from 78.6 to 19.4 ppm/oC. The results
indicate that the microwave dielectric properties of Ba5(Nb1-xTax)4O15 ceramics can be easily modified in a large range by changing the relative content of Ta to Nb.
The Influence of Bi3+ on the Sintering of Cordierite Glass Ceramic
Authors: Wang Han Feng , Zhou He Ping
Published: March 2009

The effects of Bi3+ addition on the sintering performance and microstructural evolution of cordierite were analyzed in this paper. Cordierite powders were prepared by sol-gel processing. As nucleating agent, the Bi3+ additive was found to promote the phase transition from µ-cordierite to α-cordierite and decrease sintering temperatures. The effect of Bi3+ on the activation of cordierite can be attributed to the nucleation of cordierite. The doping of Bi3+ increased the expansion coefficient and dielectric constant. Too much Bi3+ will inhibit the cordierite crystallization and encourage anorthite crystallization.
Anelasticity and Strength in Zirconia Ceramics
Authors: Matsuzawa M. , Horibe S. , Sakai J.
Published: March 2009

Non-elastic strain behavior was investigated for several different zirconia ceramics and a possible mechanism for anelasticity was discussed. Anelastic strain was detected in zirconia ceramics irrespective of the crystallographic phase and its productivity depended on the particular kind of dopant additive. It was found that the anelastic properties could be significantly influenced by the level of oxygen vacancy in the matrix, and that the anelastic strain might be produced by a slight shift of ionic species. In order to investigate the effect of anelasticity on mechanical properties on zirconia ceramics, the tensile strength was investigated for a wide range of strain rates. The obviously unique strain rate dependence was observed only in the materials having anelastic properties. It was assumed that anelasticity could be
efficient at improving the tensile strength.
Wear Behaviors of UHMWPE against LTD-Free Zirconia/Alumina Composites
Authors: Lee Myung Hyun , Seo Won Seon , Kim Hwan , Lee Kwon Yong , Kim Dae Joon , Lee Deuk Yong
Published: March 2009

The sliding wear behavior of ultra high molecular weight polyethylene (UHMWPE)
was examined on four different compositions of novel low temperature degradation-free zirconia/alumina (Z/A) composite material used for a femoral head in total hip joint replacement. The wear of UHMWPE pins against these Z/A composite disks were evaluated by performing the linear reciprocal sliding and repeat pass rotational sliding tests for one million cycles in a bovine serum. The novel low temperature degradation (LTD)-free tetragonal zirconia polycrystal (TZP)/alumina
composite (90(5.3Y, 4.6Nb)-TZP/10Al2O3) induced the less wear amount of UHMWPE than the other Z/A composites. Linear reciprocal motion wore more the UHMWPE pin than did repeat pass rotational motion for all disk materials. It was observed that few transfer film on the sliding track of Z/A composite disks and the matching contact surfaces of pins had relatively less scratch. Getting rid of transfer film, there is no change of surface roughness on the sliding track of Z/A
composite disks. This novel Z/A composite (90(5.3Y, 4.6Nb)-TZP/10 Al2O3) demonstrates the potential as an alternative material for the femoral head in total hip replacement.
16 Year Review of Hydroxyapatite Ceramic Coated Hip Implants - A Clinical and Histological Evaluation
Authors: Buchanan James M.
Published: March 2009

Traditionally implants for hip arthroplasty are secured with bone cement. Problems have been encountered with cement fixation with loosening and osteolysis attributed to the reaction to particulate cement material and also polyethylene debris from wear. Cementing techniques have been improved and the Swedish Hip Register [1] demonstrates that the revision rates have been reduced with improved cementing techniques. However, uncemented hip arthroplasty is now having a revival. In particular, bioactive materials are being used and this paper presents the results of a consecutive series of hip arthroplasties carried out over a total period of just 16 years. All the patients are included, including primary and revision hip arthroplasty.
Patients are assessed using the Harris Hip Score [2]. 13% of the hips scored less than 80 on the Harris Hip Score but only 9.4% scored poor pain scores. These represent the results of poor hip arthroplasty, of which an even smaller percentage are related to failed HA hip arthroplasty.
A Comparative Study of Bioceramics In Vitro and In Vivo
Authors: Leng Yang , Xin Ren Long , Chen Ji Yong
Published: March 2009

Bioactive calcium phosphate (Ca-P) formation in bioceramics surfaces in simulated body fluid (SBF) and in rabbit muscle sites was investigated. The examined bioceamics included most commonly used bioglass®, A-W glass-ceramics and calcium phosphates in orthopedic and dental applications. The Ca-P cyrstal structures were examined with single crystal diffraction patterns in transmission electron microscopy, which reduced possibility of misidentifying Ca-P phases. The
experimental results show that capability of Ca-P formation considerably varied among bioceramics, particularly in vivo. Octacalcium phosphate (OCP) was revealed on the all types of bioceramics in vitro and in vivo experiments. This work leads us to rethink how to evaluate bioactivity of bioceramics and other orthopedic materials which exhibit capability of osteoconduction by forming direct bonding with bone.
Cell Behaviour of Calcium Phosphate Bone Cement Modified with a Protein-Based Foaming Agent
Authors: Engel Elisabeth , Asin L. , Delgado J.A. , Aparicio C. , Planell Josep A. , Ginebra M.P.
Published: March 2009

Calcium phosphate cements (CPC) are being applied as bone regeneration materials. New methods are being developed to create macroporosity, in order enhance the angiogenesis, bone colonization and biodegradation of the material. In this study the effect of the incorporation of albumen as foaming agent in an a-tricalcium phosphate (a-TCP) cement, in terms of the surface roughness and in vitro cell response, was studied. The addition of albumen to CPC cements
increased the surface roughness of the cements. Cell cultures, using MG63 osteoblasts, were performed and showed that cell attachment was not affected by the presence of albumen. However, cell proliferation was significantly increased in the albumen-containing cements.
Effect of the Composition in β-TCP-MCPM Bone Cement Containing Dense ß-TCP Granules
Authors: Oh Kyung Sik , Kim Soo Ryong
Published: March 2009

Effect of the starting compostion was studied in bone cement containg coarse b-tricalcium phosphate (b-TCP) granules which was very dense and round. With respect to the mixing ratio between b-tricalcium phosphate and monocalcium monophophate (T:M), the properties such as setting time, density and compressive strength were measured. The properties of bone cement prepared from normal powdery b-TCP was strongly dependent on the initial mixing ratio (T:M). Though the compressive strength as well as density was maximum at T:M = 6:4, small departure of compostions from T:M=6:4 resulted in drastic decrease of compresive strength. On the contrary, in the specimens from granular b-TCP, compressive strength was much less deependent on the initial mixing ratio. Range of optimum compressive strength covered from T:M=6:4 to 8:2. Therefore,
granular groups provided more degree of freedom to control other properties such as setting time while maintaing its compressive strength.
Calcium Phosphates as Fillers in Struvite Cements
Authors: Driessens F.C.M. , Boltong M.G. , Wenz R. , Meyer J.
Published: March 2009

Struvite or magnesium ammonium phosphate MgNH4PO4 has been proposed as
active component in setting surgical cements. The usual formulation is one in which the magnesium component in the powder is either magnesium hydrogen phosphate trihydrate or trimagnesium phosphate or a mixture of these two compounds. As the cement liquid a concentrated solution of diammonium phosphate is taken. To make the cement attractive as a bone substitute material a calcium phosphate filler is generally incorporated. Thus such materials are a type of pseudo calcium phosphate cements. This study was intended to find out which calcium phosphate and which magnesium compound are the most suitable.
In the first series of experiments a mixture of 12 g Mg3(PO4)2 and 4 g MgHPO4.3H2O was used as the magnesium component in the powder. To that powder 30 g of either precipitated hydroxyapatite PHA or CaHPO4 or CaHPO4.H2O or b-TCP or a-TCP was added. The cement liquid was a 3.5 M solution of (NH4)2HPO4. At specific liquid/powder ratios L/P suitable setting times were obtained for the different formulations. However, the compressive
strengths after immersion of the cements in 0.9% saline solution at 37°C varied over a large range. The best formulation was that with a-TCP which reached a compressive strength of 57 MPa after 18 h of immersion.
In the second series of experiments 20 g of Mg3(PO4)2 was used as the magnesium component in the powder. Again 30 g of either of the above mentioned calcium phosphates was used as filler and again a 3.5 M solution of (NH4)2HPO4 was used as the cement liquid. At the appropriate L/P ratios the respective setting times were longer than in the first series of experiments but all five formulations appeared to result in good compressive strengths varying from 41 MPa for the formulation with b-TCP to 67 MPa for the formulation with PHA.
In the third series of experiments 30 g a-TCP was taken as the calcium phosphate in
the powder. As magnesium components mixtures of Mg3(PO4)2.8H2O and MgHPO4.3H2O and Mg3(PO4)2 were used. Again the cement liquid consisted of a 3.5 M solution of (NH4)2HPO4. The formulations with Mg3(PO4)2.8H2O had the shortest setting times and the lowest compressive strengths, whereas those with Mg3(PO4)2 had the longest setting times and the highest compressive strengths. Therefore, it is advantageous to use Mg3(PO4)2 as the
magnesium component.
Effect of Silica Content in the PMMA/Silica Nano-Composite on the Mechanical Properties and Growth Behavior of Calcium Phosphate Crystals during Cell Culture
Authors: Rhee Sang Hoon , Lee Yong Keun , Lim Bum Soon
Published: March 2009

The effect of silica content in the PMMA/silica nano-composite on the mechanical
properties and the growth behavior of apatite crystals were investigated. The PMMA/silica nano-composites with different silica content were synthesized through the sol-gel reaction with triethoxysilane end-capped PMMA and tetraethyl orthosilicate (TEOS). The compressive strength showed its maximum value when the content of TEOS was 20 wt% while the elastic modulus showed
its maximum value when the content of TEOS was 60 wt%. The growth behavior of the apatite crystals following the cell culture showed different response according to the silica content. As increasing the TEOS content, the shape of the apatite crystals changed from globule-like structure to fiber-like one.
Chemical and Morphological Properties of Calcium Phosphate Coatings Deposited Using the Electrostatic Spray Deposition (ESD) Technique
Authors: Leeuwenburgh Sander C.G. , Wolke Joop G.C. , Schoonman J. , Jansen John A.
Published: March 2009

The recently developed Electrostatic Spray Deposition (ESD) technique was used in order to deposit calcium phosphate (CaP) coatings onto various substrates, since this technique enables deposition of inorganic thin films with a variety of morphological and chemical properties. In the present study, the relationship between various deposition parameters and the physicochemical
properties of deposited coatings was investigated in order to be able to deposit CaP
coatings with defined chemical and morphological properties using ESD.
The results showed that the chemical characteristics of the coatings were determined by both the composition of the precursor solutions (solution acidity, absolute and relative precursor concentrations) and apparatus-related parameters, such as the liquid flow rate and the nozzle-tosubstrate distance. By varying these parameters, several crystal phases and phase mixtures were
obtained (carbonate apatite, carbonated hydroxyapatite, a/b-tricalciumphosphate, monetite, b/g-pyrophosphate, metaphosphate, calcite/calcium oxide). Coating morphology was also shown to be strongly dependent on several deposition parameters. A wide range of coating morphologies was obtained, varying from relatively dense to highly porous, reticular coating surface architectures.
A Fast Biomimetic Method for Nanocrystalline Hydroxyapatite Coatings
Authors: Bigi Adriana , Boanini E. , Bracci Barbara , Facchini A. , Panzavolta Silvia , Segatti F. , Sturba L.
Published: March 2009

We employed a slightly supersaturated solution (Ca/P) with an ionic composition simpler than that of simulated body fluid (SBF) to obtain a fast biomimetic coating on Ti6Al4V substrates.
The results of thin film X-ray diffraction, FTIR, SEM, TEM-ED investigations indicate that hydroxyapatite (HA) nanocrystals are laid down in a few hours on the susbstrates. The amount of deposition increases with the immersion time. Furthermore, the thin layer of HA deposited after 3 h soaking in Ca/P solution acts as a catalyst for the further deposition of apatite from SBF.
Use of Wollastonite in a Biomimetic Method to Promote Apatite Formation on a Co-Cr-Mo Alloy
Authors: Cortés-Hernández Dora A. , Medina Ramírez A. , Escobedo-Bocardo José C. , López M.A. , Almanza-Robles J.M.
Published: March 2009

Wollastonite ceramics was used in a biomimetic method to promote apatite formation on a Co-Cr-Mo alloy (ASTM F-75). The metallic samples were initially chemically treated in a 5M NaOH aqueous solution. The treated samples were immersed for 7 days in SBF on a bed of wollastonite and then immersed 7 or 14 days in 1.5SBF. For comparative purposes no wollastonite was used during the first 7 days in some tests. A homogeneous bonelike apatite layer was formed on the samples immersed in SBF on the wollastonite bed. The morphology and the Ca/P ratio of the layer were closely similar to those observed on the existing bioactive systems. A thinner homogeneous bonelike apatite layer was formed on the samples immersed in SBF and 1.5SBF without using wollastonite. However, the morphology and the Ca/P ratio of this layer differs slightly to that observed on the existing bioactive systems. The immersion of the samples during the first days in SBF on a wollastonite bed improves significantly the quality and thickness of the bonelike apatite layer.
Apatite Patterning by Using Electrophoretic Deposition
Authors: Yamaguchi Seiji , Yao Takeshi
Published: March 2009

Electrophoretic deposition (EPD) was applied to forming apatite pattern. A pattern of holes was formed on a polytetrafluoroethylene (PTFE) board and a porous PTFE film was superposed on the PTFE board. Wollastonite particles were deposited on the PTFE film by EPD and wollastonite pattern was obtained. Then apatite was induced at the wollastonite deposited region by soaking in a simulated body fluid.
Formation and Evolution of Hydrated Surface Layers of Apatites
Authors: Eichert Diane , Combes Christèle , Drouet Christophe , Rey Cristian
Published: March 2009

Nanocrystalline apatites exhibit a very fragile structured hydrated surface layer which is only observed in aqueous media. This surface layer contains mobile ionic species which can be easily exchanged with ions from the surrounding fluids. Although the precise structure of this surface layer is still unknown, it presents very specific spectroscopic characteristics. The structure of the hydrated surface layer depends on the constitutive mineral ions: ion exchanges of HPO4 2- ions by CO3
2- ions or of Ca2+ by Mg2+ ions result in a de-structuration of the hydrated layer and modifies its spectroscopic characteristics. However, the original structure can be retrieved by reverse exchange reaction. These alterations do not seem to affect the apatitic lattice. Stoichiometric apatite also shows HPO4 2- on their surface due to a surface hydrolysis after contact with aqueous solutions. Ion exchange is also observed and the environments of the surface carbonate ions seem analogous to
that observed in nanocrystalline apatites. The formation of a hydrated layer in aqueous media appears to be a property common to apatites which has to be taken into account in their reactivity and biological behavior.
Preparation of Poly(Lactic Acid) Composite Hollow Spheres with an Open Channel
Authors: Maeda Hirotaka , Miura Noriko , Kasuga Toshihiro , Nogami Masayuki
Published: March 2009

Novel hollow spheres for bone fillers incorporating cells were prepared using composites consisting of poly(lactic acid) and calcium carbonates. An open channel of ~800 µm in diameter was easily formed using a chemical etching method to provide a pathway to the interior of the sphere. Cells could migrate through the open channel into the interior of the sphere. Bonelike apatite coating on the surface of the sphere was prepared by soaking in calcium chloride solution to supply excess
Ca2+ ions on the surface and subsequently by soaking in simulated body fluid. The hollow spheres with an open channel may be one of the great potential candidates as novel bone fillers combined with a cell-delivery system.
Zinc-Containing Calcium Phosphate Ceramics with a (Ca+Zn)/P Molar Ratio of 1.67
Authors: Sogo Yu , Ito Atsuo , Fukasawa Koshiro , Sakurai Tokoha , Ichinose Noboru , LeGeros Racquel Z.
Published: March 2009

Zinc-containing calcium phosphate ceramics with a (Ca+Zn)/P molar ratio of 1.67
(ZnHAP ceramics) were synthesized to clarify the main phase for zinc release. ZnHAP ceramics with a zinc content at or more than 0.20 wt% contained zinc-containing tricalcium phosphate. The ion activity product of monophasic ZnHAP ceramic containing at or less than 0.13 wt% of zinc corresponded to that of pure HAP ceramic. The presence of tricalcium phosphate (TCP) phases was
necessary condition for ZnHAP ceramics to release zinc. The coexistence of TCP phases in the ZnHAP ceramics meant that a phase with a (Ca+Zn)/P molar ratio higher than 1.67 also coexisted. Although the phase was assumed to be zinc oxide, zinc was not concentrated anywhere in the ZnHAP ceramics including grain boundaries.
Biodegradation of Porous Alpha-Tricalcium Phosphate Coated with Silk Sericin
Authors: Takeuchi Akari , Ohtsuki Chikara , Kamitakahara Masanobu , Ogata Shinichi , Tanihara Masao , Miyazaki Toshiki , Yamazaki Masao , Furutani Yoshiaki , Kinoshita Hisao
Published: March 2009

Porous a-tricalcium phosphate (a-TCP) ceramics are attractive as a novel
bioresorbable material for bone repair, since they can be easily fabricated through conventional sintering of b-TCP at high temperature. However, the solubility of a-TCP is too high to keep its body until the bone defect is repaired completely. Coating of the a-TCP porous body with organic polymer is a way to reduce the degradation rate. In the present study, biodegradation of a-TCP porous body coated with silk sericin was evaluated in vivo. Bone repair at the defect made in rabbit tibia was nearly completed after 4 weeks. Higher density of cortical bone was estimated for a-TCP coated with sericin than for mere a-TCP. The a-TCP porous body coated with sericin is expected as a material that show less degradation than mere a-TCP, and may result in suitable bone repair.
Porous Hydroxyapatite with Tailored Crystal Surface Prepared by Hydrothermal Method
Authors: Ioku Koji , Kawachi Giichiro , Yamasaki Nakamichi , Fujimori Hirotaka , Goto Seishi
Published: March 2009

Porous plates of hydroxyapatite (Ca10(PO4)6(OH)2; HA) with about 0.5 to 5 mm in thickness and porous HA granules of about 40 µm to 1 mm in size with tailored crystal surface were prepared by the hydrothermal vapor exposure method at the temperatures above 105 °C under saturated vapor pressure of pure water. Porous HA plates with about 75 % porosity prepared at 120 °C were composed of rod-shaped crystals of about 20 µm in length. Porous HA granules prepared at 160 °C were also composed of rod-shaped crystals of about 20 µm in length with the mean aspect ratio of 30. These crystals were elongated along the c-axis. Rod-shaped HA crystals were locked together to make micro-pores of about 0.1 to 0.5 µm in size. Both of materials were nonstoichiometric HA with calcium deficient composition. These materials must have the advantage of adsorptive activity, because they had large specific crystal surface and much micro-pores.
Confined Compression of Bone Substitute Granules
Authors: Long Marc , Martin Charles , Cooper Mike
Published: March 2009

This study investigated the strength of several bone graft substitute (BGS) granular products under compression in a confined fixture characteristic of packing into a contained surgical bone defect. The compressive strength values for columns of granules made of tricalcium phosphate (TCP, dense), calcium carbonate / hydroxyapatite (CC/HA, porous) and ultraporous TCP (TCPu, ultra porous) were 2063.8 ±177.6N, 115.3 ±7.4N, and 40.5 ±8.3, respectively. As a result of
their higher strength, the TCP granules did not appreciably reduce in volume after packing. The CC/HA and TCPu granules appreciably reduced in volume after packing, with the final packed volumes being 68% and 41%, respectively, of their original volumes. Based on these results the TCP synthetic bone substitute granules are better able to resist crushing and retain their original volume and osteoconductive capacity during packing in a bone defect than the other BGS granules tested in this study. These properties give the dense granules with a six-arm, interlocking shape superior robustness during handling and implantation compared to other BGS scaffolds produced by porous granules, morsels or blocks, while producing a comparable osteoconductive, resorbable scaffold with interconnected porosity.
Improvement of Bioactivity of Hydroxyapatite Ceramics by Adding Glass
Authors: So Kazutaka , Fujibayashi Shunsuke , Neo Masashi , Nakamura Takashi , Anan Yukiko , Ogawa Tetsuro , Kokubo Tadashi
Published: March 2009

In this study, we examined in vivo performance of newly developed hydroxyapatite (HA)ceramics, which is obtained by sintering the HA powder mixed with CaO·MgO·SiO2-based glass at 1000°C (liquid phase sintering). Bioactivity of this glass-containing HA was evaluated compared with the control HA by mechanical test and histological examination. The glass-containing HA showed higher bone-bonding strength than the control HA throughout the experimental period. Light
microscope and backscattered scanning electron microscope (SEM) showed that the both kinds of implants bonded directly to the bone. High bioactivity in vivo, especially in the early period after implantation, of this newly developed HA was confirmed, which is one of the essential requirement for optimal bone substitutes.
In Vitro Behavior of Yttrium Silica Sol-Gel Microspheres
Authors: Cacaina D. , Viitala Reeta , Jokinen Mika , Ylänen Heimo O. , Hupa Mikko , Simon S.
Published: March 2009

Biodegradable silica microspheres containing neutron activable yttrium cations were
investigated as a potential material for in situ radiotherapy of cancers. The sol-gel method used for preparing the microspheres allows obtaining at relative low temperatures materials of high purity and homogeneity, with controlled rate of biodegradability. The influence of yttrium on the biodegradability of the silica microspheres was studied in a simulated body fluid (SBF). The chemical durability of the microspheres was investigated under in vitro conditions and the
concentration of yttrium released from the microspheres was determined.
Drug Loaded Porous Hydroxyapatite and Its In Vitro Release
Authors: Kim Y. , Song B.G. , Kim Soo Ryong , Kim Kwang Jin
Published: March 2009

Porous hydroxyapatite coated with mesoporous silica has been utilized as the matrix for controlled drug delivery. TEM observation confirms the pore size of mesoporous silica scatters about 50 Å. Porous hydroxyapatite was coated with mesoporous silica via sol-gel process. Ibuprofen and was loaded into the pores of mesoporous silica, and controlled release profiles were studied by soaking the samples in a simulated body fluid using a UV-VIS spectrophotometer.
Indirect Cytotoxicity Evaluation of Silver Doped Bioglass Ag-S70C30 on Human Primary Keratinocytes
Authors: Lohbauer U. , Jell G. , Saravanapavan Priya , Jones Julian R. , Hench Larry L.
Published: March 2009

Bioactive gel-glasses, such as the silver-doped Ag-S70C30 glass, can be used to modify the inflammatory response in a local body compartment such as in acne lesions and in nonhealing dermal wounds. In this study, the cytotoxicity of soluble silver, calcium and silica ions on human epidermal keratinocytes was investigated by measurements of mitochondrial activity (MTT assay) and neutral red dye uptake (NR assay). Ag-S70C30 extracts were prepared by soaking glass powder in complete culture medium at concentrations of 1 mg/ml and 2 mg/ml (mg of glass powder per ml of culture medium). Silver concentrations for both
concentrations of approximately 1 ppm were detected by inductive coupled plasma analysis (ICP). No negative effect on the cell viability was measured for an initial gel-glass concentration of 1 mg/ml and for the two shortest extraction times at a concentration of 2 mg/ml. Based on the results from MTT/ NR assays, a pH rise of approximately one unit had no negative effect on the NHEK-A cell viability. This preliminary study on keratinocyte viability merits future investigations on silver bioglass as a novel antimicrobial wound healing agent.