bluuebunny/crossref_metadata_2025 huggingface dataset:
In-Vitro Bioactivity Characterization of Sodium-Potassium Mica and Fluorapatite Containing Glass Ceramics
Authors: Goller Gultekin , Cekli Can , Akin Ipek , Demirkesen Erdem
Published: March 2009

The aim of this study is to find out the crystallization behaviour and in-vitro bioactivity
character of machinable glass ceramics having different ratios of Na/K mica and apatite phases, to
ascertain the best machinable composition. In order to investigate the bioactivity behavior of the
samples the simulated body fluid (SBF) was prepared. Samples were removed from the solution
after 1 hour, 1 day, 1, 2, 3 and 4 weeks. FEG-SEM was used to characterize the morphology of
precipitation HCA layer on the surface depending on time. Molecular bonding characterization of
HCA layers were carried out by using Fourier Transform Infrared Spectroscopy (FTIR) technique.
The thin film X-ray diffraction (TF-XRD) analysis was used to characterize the variation of
chemical composition on precipitated layer by time. Optimum results were obtained by the
composition, containing 70wt% Na/K mica and 30wt% fluorapatite which had an average mica size
of 3-4 microns.
Surface Dissolution of Hydroxyapatite Prepared by Microwave Sintering
Authors: Seo Dong Seok , Kim Hwan , Hwang Kyu Hong , Lee Jong Kook
Published: March 2009

The aim of this study was to prepare dense hydroxyapatite (HA) by microwave sintering and to evaluate the dissolution behavior in distilled water. Commercially-obtained HA powders having Ca/P ratio of 1.67 were used as a starting material. The as-received powder of granular type consists of nano-sized particles. Microwave sintering was operated at 1200°C for 5 min with a heating rate of 50°C/min. Microwave sintering process reduced grain size of HA, compared with the case of conventional sintering. During the immersion in distilled water for 3-14 days, grain boundary dissolution occurred and the dissolution extended into the bulk following this path. As a result, particles were separated from the structure leaving micron-scale defects.
Microspheres Based on Hydroxyapatite Nanoparticles Aggregates for Bone Regeneration
Authors: Pataquiva Mateus A. Yovana , Ferraz M.P. , Monteiro F.J.
Published: March 2009

This study concerns the preparation and characterisation of microspheres associating
alginate and two different types of hydroxyapatite (HA), which are intended to be used as drug
delivery systems and bone regeneration matrices. Hydroxyapatite nanoparticles (HA-1 and HA-2)
were prepared using a chemical precipitation synthesis based on H3PO4, Ca(OH)2 and a surfactant,
SDS (sodium dodecylsulphate), as starting reagents. These two powders of nanoHA and alginate
were used to prepare two different types of microspheres. Both powders and microspheres were
characterised using FTIR, TEM, SEM, mercury porosimetry analysis and X-ray diffraction Results
show that pure hydroxyapatite (HA) and mixtures of HA/β-TCP in the nanometre range were
obtained from both HA syntheses. Microspheres with different characteristics were obtained from
these two types of hydroxyapatite.
Preparation of Nano-Sized Strontium Containing Tricalcium Phosphate Particles
Authors: Miao Shun Dong , Weng Wen Jian , Cheng Kui , Du Pi Yi , Shen Ge , Han Gao Rong
Published: March 2009

In this work, nano-sized strontium containing tricalcium phosphate (SrTCP) particles with different strontium content were prepared using co-precipitation method in an ice-water bath and then 800°C calcination. The AAS results show that the relative Sr/(Sr+Ca) ratios are consistent with the amount of strontium added in the initial solution but larger than the designed molar percentage. The TEM micrographs demonstrate the size of the SrTCP particles is in the region of 150-400 nm while the pure TCP particle is about 500nm. The SEM photographs show the morphology of the particles before and after incorporation of strontium and it is obvious that the particle size of SrTCP decrease with the increasing of strontium content.
Effect of New Dentifrice Containing Nano-Sized Carbonated Apatite on Enamel Remineralization
Authors: Jeong S. H. , Hong Suck Jin , Choi Choong Ho , Kim B.I.
Published: March 2009

The process of dental caries is dynamic and continuous, with periods of de- and remineralization of the tooth structure occurring over time. When the remineralization potential is superior to demineralization, the caries process can be stopped and early caries lesions can recover. Moreover, the remineralization potential will be increased if active components are added to a dentifrice. Therefore, the aim of this study was to re-evaluate the remineralizaton potential of a dentifrice containing nano-sized carbonated apatite using pH cycling, which simulates the oral environment. Artificial incipient caries was induced on bovine tooth specimens, which were treated with 4 dentifrices containing several concentrations of nano carbonated apatites with pH cycling. The remineralization effect was evaluated at each step by measuring the Vickers Hardness Number, and obtaining SEM and CLSM images of the enamel surface. The micro hardness of the enamel surface increased after the pH cycling treatment of the dentifrices. The dentifrice containing 5% n-CAPs showed the highest level of remineralization followed by 0%, 15% and 30%. One-way ANOVA indicated a significant difference in remineralization between the dentifrice containing 5% and 30% n-CAPs. SEM and CLSM also demonstrated observable differences in each step. From this study, the fluoride dentifrice containing 5% n-CAPs was effective in remineralizing an artificial incipient caries lesion. In conclusion, the dentifrice containing 5% nano carbonated apatites and 25% silica was the most effective in remineralizing early caries lesion.
Development of Poly(Vinyl Alcohol)-Collagen-Hydroxyapatite Nanohybrids for Tissue Grafting
Authors: Wang Xiao Min , Li Xu Dong , Zheng Gui Qiu , Wang Xiao Liang , Zhang Xing Dong , Gu Zhong Wei
Published: March 2009

Poly(vinyl alcohol) (PVA) was introduced during in situ synthesis of hydroxyapatite (HA) in neutral collagen (COL) solution and final PVA-COL-HA nanohybrids were achieved via sequential steps including gelation by fibrillogenesis, freezing-thawing physical crosslinking, removal of unreacted residues and dehydration. This method is expected to endow the pure PVA with good bioactivity and meanwhile the presence of elastic PVA would improve the properties of COL-HA composites. The phase, microstructure and possible molecular interactions of the achieved PVA-COL-HA nanohybrids were analyzed by using X-ray diffraction, Fourier transform infra-red spectroscopy and scanning electron microscopy. The results indicate that the inorganic phase is poorly crystallized apatite with a nanometer size due to the confinement of organic macromolecules which forms a network structure.
Fabricating Hydroxyapatite–Silk Fibroin Nanocomposite by Bone Bionics
Authors: Cui Biao , Liang Lie Feng , Lu Xiao Ying , Weng Jie
Published: March 2009

In the present study, hydroxyapatite (HA) /silk fibroin (SF) nanocomposite containing 40
wt % of SF, was synthesized in an aqueous solution of CaCl2/(NH4)2HPO4 system containing SF to
mimic bone structure of nano HA crystallites in organic matrix. The experimental results show that
SF promotes the preferential growth of nano HA crystallites along the plane (002) which indicates the
interaction between nano HA crystallites and SF. The nanocomposite with nano HA crystallites
dispersed homogeneously in SF matrix possesses a compression strength of 97.6 MPa higher than
that of woven bone. The methodology has a great potential for designing and engineering of
biomaterials with improved biological properties. The novel nanocomposite may be used as bone
substitutes and tissue engineering scaffolds.
Magnetic Chitosan/Hydroxyapatite Nanocomposite via In Situ Hybridization Strategy
Authors: Li Bao Qiang , Jia De Chang , Zhou Yu , Hu Qiao Ling , Cai Wei
Published: March 2009

Magnetic hydroxyapatite/chitosan nanocomposites were prepared via in situ hybridization
strategy in the ambient condition. Magnetic hydroxyapatite/chitosan nanocomposites were
investigated by XRD, SQUID and TEM. XRD results indicated that the inorganic phases dispersed in
chitosan matrix were composed of magnetite and hydroxyapatite. The magnetic
hydroxyapatite/chitosan shown the behavior of superparamagnetism determined by SQUID, which
indicated the size of magnetite crystal were less than 30nm. The inorganic nanoparticles with size of
30-50nm were dispersed chitosan matrix homogeneously. In situ hybridization strategy provided a
simple and efficient route to synthesize the magnetic chitosan/hydroxyapatite nanocomposites in the
mild condition. The most important of in situ hybridization is that the processes of precipitation of
chitosan, synthesis of magnetite and hydroxyapatite, and compositing between three components
were completed in single step.
Synthesis of Hydroxyapatite in Polymeric Solutions for Organic-Inorganic Nanocomposites
Authors: Zheng Gui Qiu , Li Xu Dong , Wang Xiao Min , Yu Su Hong , Gu Zhong Wei , Zhang Xing Dong
Published: March 2009

Synthesis of hydroxyapatite (HA) in organic solutions has received extensive attention in recent years with an attempt to obtain HA of a nanometer level. In this preliminary study, we demonstrated that organic-HA nanocomposites could also be achieved with one step method via in situ mineralization and subsequent crosslinking of organic species. This design was realized through in situ synthesis of hydroxyapatite in poly(vinyl alcohol) and acrylic acid aqueous solution as an organic template. The aforementioned organic-inorganic nanocomposites were analyzed by using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electrical microscopy, thermal analysis. The comparative structural measurements were also conducted with the synthesized HA with absence of the organic template. The results indicated that the existence of organic species effectively inhibits the growth of calcium phosphate and that relatively pure HA can be obtained in sintered composite products. The present study provides a direct and versatile route for fabrication of nanocomposite biomaterials.
Preparation of Calcium Carbonate / Poly(Lactic Acid) Composite Membranes Containing Mercapto Groups
Authors: Tokuda Shingo , Obata Akiko , Kasuga Toshihiro
Published: March 2009

Mercapto group controls the adsorption and release of insulin, which is one of the
proteins for enhancing the osteoblast proliferation. Silicon-ion-species were reported to stimulate
the bone-forming ability of osteoblasts. The present paper describes doping with mercapto groups
and silicon-ion-species in a calcium carbonate/poly (lactic acid) composite membrane, which is
prepared by a sol-gel method using 3-mercaptopropyltrimethoxysilane. The membrane was
amorphous and showed high flexibility. A quantitative analysis by thiol-disulfide exchange reaction
using 2, 2-dipyridyl disulfide reagent showed that the amount of mercapto group existing on
membrane surface was estimated to be about 5.51μmol/cm2. A trace amount of silicon-ion-species
was released from the membrane after soaking in tris (hydroxymethyl) aminomethane buffer
solution at 37 oC. The membrane is expected to have high bone-forming ability.
Slip Casting Derived α-TCP/HA Biphasic Ceramics
Authors: Cheng Kui
Published: March 2009

Biphasic α-tricalcium phosphate/hydroxyapatite (α-TCP/HA) calcium phosphate (BCP)
is prepared through a modified slip casting based method: α-TCP powders are dispersed in the HA
precursor solutions to form castable slurries, then the slurries are poured into round mold. After
curing, the slurries turn into cakes. Room temperature curing leads the cakes to contain α-TCP and
HA phases. Higher temperature heat treatment will result in the increase of HA content, while even
higher temperature will leads the cakes to be triphasic. Low temperature derived BCP have
particular microstructure with HA covers the surface of α-TCP powders, and these powders further
agglomerate into large blocks. After higher temperature treatment, β-TCP dominates the cake and
microporous structure is resulted.
Calcium Phosphate Coatings on Titanium Alloy via an Electrodeposition Method
Authors: Lopez-Heredia Marco A. , Weiss Pierre , Layrolle Pierre
Published: March 2009

Calcium phosphates coatings were deposited onto titanium discs via en electrodeposition method. Discs were blasted with calcium phosphate particles and etched in a mixture of sulfuric and fluoric acids. Temperatures from 25 to 80°C and current densities from 8 to 120 mA/ cm2 were used. Deposition times tested were between 10 and 120 min. The electrolyte consisted of a super saturated solution stirred at 250 rpm. The amount of magnesium (Mg2+) and carbonate (HCO3-) ions was varied from 0 to 1 mM. Coatings increased in thickness by increasing deposition time. The different amounts of Mg2+ and HCO3- affected the homogeneity and morphology of the coatings. Main factors affecting the deposition were temperature of electrolyte and current density.
Early Peri-Implant Osteogenesis with Functionally Graded Nanophase Hydroxyapatite/Bioglass Coating on Ti Alloys
Authors: Tan Yan Bin , Wang Xiang Hua , Wu Qiong Hua , Yan Wei Qi
Published: March 2009

Although compositional gradients could be manufactured for the functionally graded
coating that was showed to improve bonding strength between the coating and the substrate, the
biological efficacy of the graded coatings remained unclear. In this study, a functionally graded
nanophase hydroxyapatite/bioglass (n-HA/bioglass) coating was prepared on a titanium (Ti)
substrate for evaluating peri-implant osteogenesis in a canine model. The bone apposition and
osteointegration of n-HA/bioglass coating were investigated at the interface compared with plasma
spraying HA (PS-HA) coating. The results showed that the coating degraded gradually over time but
not as fast as PS-HA coating did, and that more active bone apposition appeared on the n-HA/bioglass
coating. The in vivo study indicated that an early osteogenesis and osteointegration at the interface
could be stimulated by the use of n-HA/bioglass coating in biological environment.
The Effects of Ion Beam-Assisted Deposition of Hydroxyapatite on the Osseointegration of Endosseous Implant Surface
Authors: Kim M.K. , Choi Jung Yoo , Jung Ui Won , Lee In Seop , Inoue T. , Choi Seong Ho
Published: March 2009

The aim of this study is to evaluate the effects of coating implants with hydroxyapatite
(HA) by an ion beam-assisted deposition (IBAD) method and to compare them with implants
prepared with machined and anodized surfaces. Twenty-four implants in this study were divided into
three groups; machined, anodized, anodized plus IBAD surface implants. Implant stability and
osseointegration were assessed by resonance frequency analysis (RFA) and histologic analysis. We
can conclude that implants coated by HA by IBAD demonstrate characteristics of contact
osteogenesis, but the research design does not permit conclusions regarding long-term treatment
outcome with implants. Further studies are needed.
Different Morphology of Hydroxyapatite Coatings on Titanium by Electrophoretic Deposition
Authors: Meng Xian Wei , Kwon Tae Yub , Kim Kyo Han
Published: March 2009

The objective of the present study was to define the optimal conditions and
characterizations of hydroxyapatite (HA) coatings on titanium by electrophoretic deposition (EPD).
The EPD processing parameters, such as deposition time, HA concentration level in the suspension,
and applied voltage are experimentally determined. A good packing, crack-free and uniform HA
coating on titanium was prepared. Then the coatings were sintered at 800 °C for 2 h. The sintered
coatings presented a very homogeneous polycrystalline structure free of cracks. The results show
that the application of EPD is an effective method in obtaining HA coatings with good properties.
Biomimetic Coating on Titanium Metal and Its Excellent Cell Proliferation
Authors: Yang Xiu Dong , Teng Li Zhao , Lu Jian , Wei Qing Rong , Wang Hui , Chen Ji Yong , Yang Bang Cheng
Published: March 2009

Biomimetic coating on roughed titanium plates were prepared in this work by a cathode deposition method in calcium phosphate solution electrolyte. The coatings of plate-like apatite crystals were deposited on the titanium plates under a constant potential of 2.0V for 60 min at 37. The coating crystals were identified to be carbonate-containing apatite (bone-like apatite) by X-ray diffraction and scanning electronic microscopy. The cell proliferation and adhesion of L929 cells on the titanium metal plates with biomimetic coating and the titanium plates with roughed-only were tested. The results showed that biomimetic coating on titanium surface can enhance the materials bioactivity. The study indicated that cathode method is potential to prepare biomimetic coating on titanium implants with excellent bioactivity.
Research on the In Situ Fabrication of Bioceramic Composite Coatings by Laser Cladding
Authors: Wang Ying Chun , Li Jian Guo , Zhou Yaohe
Published: March 2009

Hydroxyapatite(HAP) has excellent osteoconductive properties. By controlling the Ca/P
ratio better biphasic calcium phosphate ceramics can be produced than pure HAP ceramics. β-
calcium pyrophosphate(β-Ca2P2O7) is a new biodegradable ceramic material and its biological
response is quite similar to HAP. Obtaining HAP and other bioactive calcium phosphate ceramic
coatings has been a popular research field in the past. In our research a new bioceramic composite
coating was obtained by laser cladding with pre-depositing mixed powders of CaHPO4·2H2O and
CaCO3 directly on the metal substrate. Its main constituents are HAP and β-Ca2P2O7. The
microstructure of the coating consists of minute granular HAP that is distributed among the
overlapped club-shaped or needle-like β-Ca2P2O7. The hardness distribution in the cladding layer is
even and its value is much higher than that in the substrate. There is a bonded structure of the
epitaxial planar growth between the substrate and cladding layer, and both a typical cellular
microstructure in the middle and an equiaxed microstructure at the top of the cladding layer.
Preparation of Bioactive Tantalum Metal via Anodic Oxidation Treatment
Authors: Yang Bang Cheng , Gan L. , Li Zhen Sheng , Huang Y. , Qu Yang , Zhang Xing Dong
Published: March 2009

After the Tantalum metal was subjected to the anodic oxidation at suitable voltage in
2M H2SO4 solution, tantalum oxide with rhombic or amorphous structure formed on the metal
surface. The Oxide showed apatite formation ability in simulative body fluid at 6d. It meant the
anodic oxidation treatment ia an effective method to accelerate the bioactivity of tantalum metal.
Preparation of Merwinite with Apatite-Forming Ability by Sol-Gel Process
Authors: Ou Jun , Yin Guang Fu , Zhou Da Li , Chen X. C. , Yao Ya Dong , Yang Wei Zhong , Wu Bo Lin , Xue Ming , Cui Jun , Zhu Wen Feng , Kang Yun Qing
Published: March 2009

Merwinite powders were synthesized by a sol-gel process. The bioactivity in vitro of merwinite was
investigated by soaking the powders in simulated body fluid (SBF), the growth of hydroxyapatite(HAp) on the
surface of the powder was evaluated in various time. It was found that hydroxyapatite was formed after soaking
for 14 days. The results indicate that merwinite possessed apatite-formation ability might be a potential candidate
biomaterial for hard tissue repair.
FGF-2/Calcium Phosphate Composite Layer to Resist Bacterial Infection
Authors: Sogo Yu , Ito Atsuo , Mutsuzaki Hirotaka , Oyane Ayako , Onoguchi M. , Ichinose Noboru , Sakane Masataka , Ochiai Naoyuki
Published: March 2009

A FGF-2-apatite composite layer (FGF-AP layer) was formed on the surface of Ti screws
in a supersaturated calcium phosphate solution supplemented with FGF-2. By an in vitro study
using fibroblastic NIH3T3 cells, it was confirmed that FGF-2 was immobilized in the layer without
complete denaturation although the composite layer was formed at 37°C. When Ti screws with the
FGF-AP layer were percutaneously implanted in the proximal tibial metaphysis of 16 rabbits, no
osteomyelitis was observed in any rabbits although a FGF-2-free AP layer allowed osteomyelitis in
some cases in our previous study. These results suggest that a FGF-AP layer formed on Ti screws is
useful for resisting bacterial infection during external fixations.
Hydroxyapatite Formation on Alumina Surface Modified by Aluminoxane
Authors: Bertran Celso A. , Bertazzo S. , Almeida L.L. , Souza Jr. A.V.
Published: March 2009

The surface of alumina discs (γ phase) was modified by the reaction between the Al-OH groups on the surface of alumina and oxalic acid, resulting in carboxylatoaluminoxanes. The alumina discs with modified surface were soaked in SBF for 6 hours, promoting an intense precipitation of calcium phosphate. The formation of evenly distributed calcium phosphate crystals controlled by the alumina surface, achieved in this work, has the potential to significantly modify the bioinert behavior presented by this material.
The Synthesis and Initial Studying Anticoagulant Property of O-Doped DLC Films by DC-MFCVAD
Authors: Wen Feng , Huang Nan , Sun Hong , Jing Feng Juan , Zhao An Sha
Published: March 2009

O-doped Diamond-Like carbon (O-DLC) films were prepared by direct magnetic filtered
cathodic vacuum arc deposition (DC-MFCVAD) under different O2 gas flow at room temperature
(R.T.). Raman spectra were used to characterize structure of films. The wettabilities of the O-DLC
films also were investigated by contact angle measurements using four common liquids. For
studying films’ interaction with blood, platelet adhesion experiment in vitro was done to
characterize anticoagulant property of the O- DLC films from an aspect. Furthermore, ultraviolet
spectrophotometer was employed to measure the optical band gap of the synthesized films. All of
the results showed that O-DLC films have good anticoagulant property, oxygen doping can prevent
graphite-like tendency of DLC films and increase band gap in a way, this kind of film materials
may be become a new candidated biomaterials.
Behaviors of Platelets Adherent on Si-N(H) Surface Prepared from Ammonia Plasma-Implanted Silicon
Authors: Wan Guo Jiang , Huang Nan , Zhao An Sha , Yang Ping , Chu Paul K.
Published: March 2009

Ammonia implanted silicon was performed by using plasma immersion ion implantation
(PIII) to form a silicon nitride films. Blood compatibility of the prepared samples was investigated
by platelets adhesion testing. It showed less activation i.e. lower thrombosis risks occurs on the
prepared silicon nitride films than control silicon sample. The enhanced blood compatibility of the
material is attributed to the modified surface properties such as hydrophilicity from thermodynamic
adsorption perspective, which is related to surface chemical bonding states achieved by PIII
process.
Fabrication and Mechanical Properties of Dense/Porous β-Tricalcium Phosphate Bioceramics
Authors: Zhang Fa Ming , Chang Jiang , Lu Jian Xi , Lin Kai Li
Published: March 2009

Attempt to increase the mechanical properties of porous bioceramics, a dense/porous
structured β-TCP bioceramics that mimic the characteristics of nature bone were fabricated.
Experimental results show that the dense/porous structured β-TCP bioceramics demonstrated
excellent mechanical properties with compressive strength up to 74 MPa and elastic modulus up to
960 MPa, which could be tailored by the dense/porous cross-sectional area ratio obeying the rule of
exponential growth. The interface between the dense and porous bioceramics is connected
compactly and tightly with some micropores distributed in the matrix of both porous and dense
counterparts. The dense/porous structure of β-TCP bioceramics may provide an effective way to
increase the mechanical properties of porous bioceramics for bone regeneration at weight bearing
sites.
Fabrication and Characterization of Bioactive Composite Scaffolds Based on β-TCP-BG-PLA for Bone Tissue Engineering
Authors: Zhao Na Ru , Wang Ying Jun , Chen Xiao Feng , Ning Cheng Yun
Published: March 2009

In this study, the bioactive composites based on β-tricalcium phosphate (β-TCP),
bioglass (BG) and poly lactic acid (PLA) were prepared. The microstructure, degradability and
reaction products of the scaffold soaked in a simulated body fluid (SBF) at 36.5°C for different days
were characterized through scanning electron microscopy (SEM), energy-dispersive X-ray analysis
(EDS), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and induced
coupled plasma spectroscopy (ICP). The weight loss and strength decrease with the time were tested.
The results showed that at the same porosity, the degradability of the scaffold samples decreased as
followed: β-TCP/BG/PLA>β－TCP/BG>β－TCP.The materials had highly bioactive response
ability to the Simulate Body Fluid (SBF) and promptly induced a bone like HA layer on the surface
of the scaffolds when immersed in the SBF.
Study on Tissue Engineering Scaffolds of Silk Fibroin-Chitosan/ Nano-Hydroxyapatite Composite
Authors: Wen Guang Wu , Wang Jing , Li Mu Qin , Meng Xiang Cai
Published: March 2009

The porous scaffolds of silk fibroin-chitosan /nano-hydroxyapatite (SF-CS / n-HA) were fabricated through the freeze- drying technique. Component, structure and morphology of scaffolds were studied by infrared (IR), X-ray diffusion (XRD) and scanning electron microscope (SEM), and the mechanical properties of the scaffolds were measured. The simulated body fluid (SBF) experiments were conducted to assess the bioactivity of the scaffolds. Results indicate that chemical binding is formed between HA and organics, the macropore diameter of the scaffolds varies from 150 to 400μm. The porous scaffolds with interconnected pores possess a high porosity of 78%-91% and compressive strength of 0.26 -1.96MPa, which can be controlled by adjusting the concentration of organic phases and prefreezing temperature. In the SBF tests, a layer of randomly oriented bone-like apatite crystals formed on the scaffold surface, which suggested that the composite material had good bioactivity. Studies suggest the feasibility of using SF-CS /n-HA composite scaffolds for bone tissue engineering.
Porous and Bioactive Alumina Ceramics for Bone Grafts and Tissue Engineering Scaffolds
Authors: Su B. , He X. , Dhara S. , Mansell J.P.
Published: March 2009

An environmentally friendly direct foaming method was investigated to produce porous alumina ceramics. Egg white protein was used as a binder and foaming agent. The microstructures show that pores are interconnected with pore size of a few hundreds μm and pore window size of ca. 50 μm. The compressive strength of alumina foam is up to 100 MPa depending on porosity. Bioactivation of alumina was carried out using an alkaline solution treatment. Hydroxylation of alumina was achieved using 5M NaOH at 80°C for 4 days. In vitro assessments of the alumina in a human osteoblast cell-like cell (MG63) culture showed that the bioactivated alumina foams exhibited better cellularity and alkaline phosphatase (ALP) activity compared to untreated alumina foams. The results indicate that it is possible to improve the osseointgration of alumina ceramics by structural and surface modifications and to extend the applications of biocompatible alumina ceramics in biomedical implants and tissue engineering scaffolds.
Modelling Failures of Thermal Barrier Coatings
Authors: Karlsson Anette M.
Published: March 2009

Thermal barrier coatings are commonly used in high temperature parts of gas turbines, to protect the underlying metal substrate from deterioration during high temperature exposure. Unfortunately, the coatings fail prematurely, preventing the design engineers to fully utilize their implementation. Due to the complexity of the coatings, there are many challenges involved with developing failure hypotheses for the failures. This paper reviews some aspects of the current stateof- the-art on modeling failures of thermal barrier coatings, focusing on mechanics based models (such as finite element simulations) where the material physics is incorporated (such as oxidation and diffusion).
Flaw Tolerant Ceramic Laminates with Negligible Residual Stresses between Layers
Authors: Bueno S. , Baudín Carmen
Published: March 2009

Ceramic laminates can be designed to combine high strength with flaw tolerance. In this paper, the designing approach based on the mechanical response of residual stresses free biological layered structures is revised. The main design tools are analysed and different ceramic-ceramic systems combining stiffness, high strength and flaw tolerance with thermo-mechanical stability are described. Two main approaches have been used depending on the relative toughness of the layers and the interfaces between them. Laminates constituted by layers separated by weak interfaces, to originate crack deflection and delamination along the interface, show high thermal shock resistance but limited resistance to shear stresses and, thus, to wear. Laminates with strong interfaces that combine stiff and high strength external layers with flaw tolerant internal ones are appropriate for wear applications. In this group of materials, the combination of layers with the same phase composition and different microstructures avoids residual stresses due to thermal expansion mismatch, but the attainment of such microstructural differences implies the co-sintering of layers with large differences in the green state. The generation “in situ” during sintering of the desired microstructural differences represents an interesting alternative in terms of processing for this group of materials.
Ceramic Layer Composites in Advanced Automotive Engineering and Biomedical Applications
Authors: Gadow Rainer
Published: March 2009

Light weight engineering and composite technologies are key strategies in modern product development in mechanical engineering as well as in biomedical applications, where innovation is driven by novel material concepts and surface functionalities. Designed or customized surface properties by advanced coating technologies are an important discipline in this context. Ceramic, metallurgical and cermet layers can be manufactured in a most appropriate way by high energetic thermokinetic deposition techniques like plasma spraying, electric arc and last not least by supersonic flame spraying (HVOF). These technologies perform high deposition rates, high flexibility to use various materials and their combinations and applications in micro to macro scale products. The final properties of the coatings and layer composites do not just depend on the properties of the combined materials but, as in the case of ceramic coated light metals, are distinctly affected by the occurring residual stresses and their interaction with operational load stresses. With respect to the complex geometries of most components, their dimensional and positional tolerances a further strong influence of the robot kinematics of the plasma or HVOF torches during coating manufacturing is observed. By combining the expertise in materials and manufacturing engineering coatings and composites with high performance and reliability can be achieved. This is shown in the development of functionally coated cylinder liners and crankcases for ultra light weight engines as well as for ceramic coated bioinert and biodegradable substrates in medical surgery. It will be shown that cast engine block bores can be directly coated by using an automated HVOF process, obtaining improved coating results. The internal coating process by hypersonic flame spraying is a superior technological alternative to the APS process for high quality cylinder liner and engine crankcase applications. The applications of such ceramic and cermet coatings are not limited to automotive and biomedical applications, i. e. for wear and friction properties or biomedical compatibility, but can be used for tailored thermophysical, electrophysical or catalytic properties in various technical systems.
Glass-Alumina Functionally Graded Materials Produced by Plasma Spraying
Authors: Cannillo Valeria , Lusvarghi Luca , Manfredini Tiziano , Montorsi M. , Siligardi Cristina , Sola A.
Published: March 2009

The present work was focused on glass-alumina functionally graded materials. The
samples, produced by plasma spraying, were built as multi-layered systems by depositing several
layers of slightly different composition, since their alumina and glass content was progressively
changed. After fabricating the graded materials, several, proper characterization techniques were set
up to investigate the gradient in composition, microstructure and related performances. A particular
attention was paid to the observation of the graded cross sections by scanning electron microscopy,
which allowed to visualize directly the graded microstructural changes. The scanning electron
microscopy (SEM) inspection was integrated with accurate mechanical measurements, such as
systematic depth-sensing Vickers microindentation tests performed on the graded cross sections.
Strain Mismatch in Ceramic Multilayers: Determination by Strength Measurements
Authors: Pascual Javier , Chalvet Francis , Lube Tanja , de Portu Goffredo
Published: March 2009

In asymmetrical 3-layer laminates with constant overall and inner layer thickness, the
residual compressive stresses in the two outer layers are not longer the same: compression is higher
in the thinner layer.Therefore, it can be expected that the strength also depends on the outer layer
thickness. Experimental evidence of this behavior was found by measuring the bending strength of
asymmetrical tri-layers. A value of the thermal expansion mismatch was determined by fitting the
theoretical expression to the experimental data.
Development of FGM Monomorph Actuator for Impedance Pump Application
Authors: Chen Yan Hong , Li Tao , Ma Jan , Boey F.Y.C.
Published: March 2009

In the present work, the FGM monomorph actuator was developed and applied in the
impedance pump. The actuator was fabricated using electrophoretic deposition (EPD). Two starting
materials, pure PZT and doped PZT, were mixed to form four different compositions. The actuator
was then fabricated by sequential deposition of the four compositions layer by layer on the substrate
and followed by sintering to full density. The actuator shows both piezoelectric property and
microstructural gradient across the layers. The actuator is able to achieve a bending displacement of
nearly 2 mm at resonant frequency. It has been successfully applied to the impedance pump as the
actuating component. The pumping action comes from the periodic compression by the actuator to
induce a net flow. Maximum flow was observed at the resonant frequency of the actuator. A flow rate
of about 9 ml/min was generated.
Mechanical Performance of an Animal-Based Silk/Polymer Bio-Composite
Authors: Cheung Hoi Yan , Lau Alan Kin Tak
Published: March 2009

There has been a concern over many years on the usage of existing metallic and ceramicbased
biomaterials for implant design and development due to the necessity of conducting
operations for patients to remove and maintain implants after they complete their desired functions.
Recently, the development of biodegradable polymers like poly(glycolic acid), poly(lactic acid),
and their co-polymers etc. have emerged and provided an entirely new concept to tackle this
problem as these polymers can be fully or partly degraded or resorbed by the human body, i.e. an
extra operation for removing the implants can be avoided, which can highly alleviate the hard
feeling of the patients that come from psychological and physiological pressures. Natural fibres
have been well recognized as potential micro-reinforcements for the enhancement of mechanical,
thermal and structural properties of biodegradable polymer composites, without generating any
harmful by-products and adverse effects during their degrading process to the patients. These
natural fibers can be mainly classified depending on their origin into two categories; they are (i)
plant-based and (ii) animal-based natural fibers, like spider and silkworm silks.
Since the last decade, silkworm silks have been used as reinforcements for fabricating biocomposites.
However, no comprehensive study, particularly on the correlation between the
mechanical properties of the composites, and fiber orientations and configurations has been done to
date. In this paper, an in depth study on the mechanical properties of silk/epoxy composites with
different fiber contents and orientations, through experimental approach and fractographic
examinations will be conducted. Tensile property tests for all silk/epoxy composite samples will be
performed. Failure samples will be examined by using scanning electron microscope (SEM) to
investigate the failure mechanism of the composites.
Finite Element Analysis of Vibration Damping for Woven Fabric Composites
Authors: Nakanishi Yasumasa , Matsumoto Kin'ya , Zako Masaru , Yamada Yukiko
Published: March 2009

The estimation method of the damping properties for woven composites has proposed. The
proposed method has been applied to the plain woven composites. From these results, it is recognized
that the computational damping properties have agreed with the experimental ones. Next, the effect of
angle of fiber bundle on material damping of plain woven composites has investigated. The results
show that the damping ratio is highest at angle of 45 degree.
Adhesion Issues in PBO/Epoxy Composites
Authors: Liu J. , Gao Shang Lin , Mäder Edith , Bianchi A.D. , Herrmannsdörfer Thilo , Zherlitsyn S. , Zvyagin B.S.A. , Wosnitza J.
Published: March 2009

The high performance of poly p-phenylene-2,6-benzobisoxazole (PBO) fibre in
mechanical properties and environmental resistance provides great potential applications as
reinforcement fibres for composites. However, poor adhesion between PBO fibre and matrix is found
because of the chemically inactive and/or relatively smooth surface of the reinforcement fibre. Here,
we report the surface modification of PBO fibres by O2 and NH3 plasma treatments. The surface
energy and roughness are increased for both sized and extracted fibres after plasma treatments. The
sized fibre shows marginal improvement in interfacial adhesion and no change in fibre tensile
strength because of the barrier effect of the sizing layer. For the extracted fibre, the plasma treatments
cause reduction in both interfacial adhesion and the tensile strength, which is sensitive to plasma
treatment conditions as revealed by a bimodal Weibull statistical distribution analysis. The fibre
surface roughness is increased and more surface flaws are induced, which could result in coarse
interface structures when the treated fibre surface has no adequate wetting and functional groups.
Mechanical Behaviours for Textile Composites by FEM Based on Damage Mechanics
Authors: Kurashiki Tetsusei , Nakai Hiroaki , Hirosawa Satoru , Imura Makoto , Zako Masaru , Verpoest Ignaas , Lomov Stepan
Published: March 2009

To make an expansion of composite consumption ever widening with use at demanding
and safety critical applications, it is important to establish the evaluation technique of the strength,
the safety, etc. To reach the goal with a useful reliable technique, we have developed a numerical
simulation program on damage development of composites based on damage mechanics. The
following points are the keys to simulate the mechanical behavior; (1) The generation technique of
FE model with yarns and matrix, (2) The classification of anisotropic damage mode based on damage
mechanics, (3) Multi-scale modeling by Mesh superposition method. In this paper, the numerical
technique and the results of multi-scale analysis of woven composites are described.
Mechanical and Thermal Behavior of a Polymer Composite Reinforced with Functionalized Carbon Nanotubes
Authors: Wong Ka Keung , Shi San Qiang , Lau Alan Kin Tak
Published: March 2009

Although many studies have been conducted in the past few years on the possibility of
using carbon nanotube (CNT) to improve the performance of polymer-based materials, some of the
results were contradictory and lack of coherence. Thus, the in-depth understanding of CNT
composites is required. In this paper, single-walled carbon nanotubes (SWNTs), which were
functionalized by sonicating with nitric and sulfuric acids, will be used to fabricate a SWNT/epoxy
composite. There are two reasons for functionalizing the SWNTs, they are (i) to improve the
dispersion of the SWNTs in polymer, and (ii) to improve the interfacial bonding properties between
the SWNTs and polymer matrix. Tensile property test and micro-hardness test will be carried out to
examine the mechanical properties of the composites with different SWNT contents.
Thermogravimetry Analysis (TGA) will be used to evaluate the thermal properties of the composites.
Scanning Electron Microscope (SEM) will also be used to investigate the failure mechanism of the
composites after tensile test. A comparison of the composites with functionalized and
non-functionalized SWNTs will be given to elaborate the effect of nanotube functionalization.
Characterisation and Object-Oriented Finite Element Modelling of Polypropylene/ Organoclay Nanocomposites
Authors: Dong Y. , Bhattacharyya Debes , Hunter P.J.
Published: March 2009

Although much research work has been conducted on the production and characterisation
of polypropylene/organoclay nanocomposites, the effects of nanoscale fillers with respect to actual
morphology through numerical modelling have been rarely addressed. This paper describes a
unique development from fabrication and experimental characterisation to the numerical modelling
of polypropylene/organoclay nanocomposites based on the real mapping of nano/microstructures.
Twin screw extrusion is used with a two-step masterbatch compounding method to prepare such
nanocomposites with organoclays (ranging between 1wt% and 10wt%) and maleated polypropylene
(1:1 weight ratio). The material characterisation using X-ray diffraction (XRD), scanning electron
microscopy (SEM) and dynamic mechanical analysis (DMTA) are conducted and mechanical
properties are determined by tensile, flexural and impact tests. Finally, computational models are
established by using an innovative object-oriented finite element analysis code (OOF) to predict the
overall mechanical properties of nanocomposites.
Spark Plasma Sintering of CBN-WC-10Co Composites
Authors: Shi Xiao Liang , Shao Gang Qin , Duan Xing Long , Yuan R.Z.
Published: March 2009

Nanocomposite WC-10Co powder produced by spray pyrolysis-continuous reduction &
carbonization technology and cubic boron nitride (CBN) plated with titanium by vacuum vapor deposit
were used, and this paper adopted spark plasma sintering (SPS) process to prepare CBN enhanced
ultrafine WC-10Co cemented carbide cermets composite material. The microstructure and mechanical
properties of CBN-WC-10Co composites were investigated. The results show that CBN-WC-10Co
composites consolidated by spark plasma sintering can reach 95.0 % relative density, and transverse
rupture strength (TRS) is 1050 MPa, the average grain size of cermets matrix is less than 420 nm, and
CBN-WC-10Co composites with excellent properties are achieved. The CBN still remains very good
crystal shape after 1240°C spark plasma sintering, and there is not obvious clearance between CBN plated
with titanium and the cermets matrix, the coated titanium layer can not only improve the thermal stability
of CBN, but also increase the properties of CBN-WC-10Co composites.
Comparison of Spark Plasma Sintering and Hot Pressing of MgAlON
Authors: Huang Qing , Zhang Hou Xing , Huang Yong , Li Hai Feng , Wan Zhi Jian
Published: March 2009

MgAlON ceramics were prepared by spark plasma sintering (SPS) and hot pressing (HP), respectively. It was found that SPSed MgAlON samples had a single MgAlON phase with almost no open pore while HPed MgAlON had a minor AlN phase. The strength of SPSed samples is higher than 500MP, being much higher than that of the HPed samples. The experimental results revealed that that SPS was a rapid and reliable process for the further development of MgAlON.
Tape Casting of Ba0.7Sr0.3TiO3 for Tunable Microwave Devices
Authors: Ai Chen , Xue Hao , Zhou He Ping
Published: March 2009

In this work, tape-casting technique was employed to prepare Ba0.7Sr0.3TiO3 films for lens
antenna system. Effects of slurry properties on the tape casting procedure were investigated and the
thickness, tensile strength and the surface roughness of the tapes were studied. The structure, morphology
and the dielectric properties of the films were analyzed.
Electrophoretic Deposition Ba0.65Sr0.35TiO3 Thick Films for Tunable Microwave Devices
Authors: Xue Hao , Ai Chen , Zhao Wei , Zhou He Ping
Published: March 2009

Pure barium strontium titanate (Ba0.65Sr0.35TiO3) and MnO2-modified barium strontium titanate (Ba0.65Sr0.35TiO3-MnO2) thick films were fabricated by electrophoretic deposition technique. The structures and morphologies of the films were analyzed. The dielectric measurements were conducted on metal-insulator-metal capacitors using platinum as the bottom electrodes and gold as the top electrodes. The dielectric constants and dissipation factors of Ba0.65Sr0.35TiO3 and Ba0.65Sr0.35TiO3-15wt% MnO2 thick films were measured at a frequency of 1 MHz. The tunabilities of 12.5% and 9.3% were obtained for Ba0.65Sr0.35TiO3 and Ba0.65Sr0.35TiO3-MnO2 thick films under an applied electric field of 15 kV/cm, respectively. The dielectric properties of the present thick films were suitable for tunable microwave device applications.
Microstructure and Mechanical Properties of Ce-Y-TZP Ceramic Composites for Ceramic Plunger and Ball Valve
Authors: Zhang Bao Qing , Lin Xu Ping , Ma Jing Tao
Published: March 2009

Microstructure and mechanical properties of CeO2/Y2O3/ZrO2 ceramics were investigated
using ultrafine CeO2/Y2O3/ZrO2 powder as the starting material. The structures of CeO2/Y2O3/ZrO2
containing 8~12mol% CeO2 were composed of tetragonal phases. They exhibited an extremely high
bending strength (950 MPa) and fracture toughness (12MPa·m1/2). The structural details of CeO2/Y2O3/
ZrO2 were studied by TEM, SEM and XRD. The effects of the structure on mechanical properties were
discussed. Plungers and ball valves by the CeO2/Y2O3/ZrO2 ceramics have higher wear resistance and
corrosion resistance than metal. Their service life is about 6 ~ 10 fold more than that of metal.
Microstructures and Mechanical Properties of Nano-Composite Ti(C,N)-Based Cermets
Authors: Liu Wen Jun , Zheng Yong , Xiong Wei Hao
Published: March 2009

Several nano-composite Ti(C, N)-based cermets were produced by vacuum sintering and
subsequently heat-treated with hot isostatic pressing (HIP) in Ar. The influence of nano powder additions
on the microstructures and properties of cermets has been studied It was found that, with increasing nano
powder additions, the microstructures became finer and even, the amount of small grains with inner-rim,
outer-rim and those with “white core-gray rim” increased. When nano TiC and TiN additions accounted
for 20wt% of the amount of TiC and TiN, the samples exhibited the best properties. Some nano particles
were found to distribute at (along?) the grain boundaries of cermets, which strengthened the grain
boundaries and improved the mechanical properties of Ti(C, N)-based cermets.
Ablated Transformation and Dielectric of SiO2/SiO2 Nanocomposites Dipped with Silicon Resin
Authors: Cao Mao Sheng , Jin Hai Bo , Li Jin Gang , Zhang Liang , Xu Qiang , Li Xiang , Xiong Lan Tian
Published: March 2009

SiO2/ SiO2 nanocomposites dipped with silicon resin was ablated and the physical state and
phase transformation were characterized. Trace impurity in raw material and compound obtained by
chemical reaction were analyzed. Moreover, the high-temperature dielectric properties were investigated.
On the basis of above, it is found that the impurity carbon and silicon carbide are the key factors
influencing dielectric properties.