bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Weld Tip Geometry on Ultrasonic Welding of Aluminum Alloy
Authors: Watanabe Takehiko , Nishihara Kosuke , Sasaki Tomohiro
Published: January 2010

Authors ultrasonically welded A6061 aluminum alloy sheet using two types of weld tips with the different contact face geometry, and investigated the effect of the weld tip geometry on the performance and the interface structure of welds. One type of tip has a cylindrical contact face without knurl, which is called C-tip in this study. The other type of tip has flat contact face with knurl, which is called K-tip in this study. The strength of the joints welded using C-tip was higher than that welded using K-tip and the C-tip could stably produce the higher strength joint.
Intelligent Control of Arc Welding Dynamics during Robotic Welding Process
Authors: Chen San Ben , Wang W.Y. , Ma H.B.
Published: January 2010

This paper presents a sequential research works on visual information acquirement and intelligent control of arc weld pool dynamics and seam formation during pulsed GTAW (Gas Tungsten Arc Welding) in robotic welding process. The visual information acquirement methods are focused in computer vision sensing, image processing and characteristic extraction of the weld pool surface from the single-item pool images by particular algorithms for robotic welding process. Based on acquired visual characteristics of weld pool and established neural network and knowledge models for predicting dynamical characteristics of weld pool during robotic welding, corresponding control methods, such adaptive control, self-learning and other composite intelligent control strategies are developed to control welding pool dynamics during pulsed GTAW by welding robot. Some experiments and applications of intelligent control methods in welding robot systems are shown in the paper.
Interfacial Behavior of Dissimilar Friction Welded Nodular Cast Irons with Low Carbon Steels
Authors: Mitelea Ion , Crăciunescu Corneliu Marius , Gugu R.
Published: January 2010

Welding of dissimilar materials is frequently accompanied by structural and technological difficulties and not always successful. The knowledge resulting from dissimilar welding experiments can be used to further identify directions and suitable technological parameters for optimal results.
This paper report on the difficulties encountered on friction welding of nodular cast irons with low alloyed steels, due in principle to the low deformation capacity and the microstructural differences.
It was shown through experiments that low friction times and high axial pressure leads to a significant plastifiation of the cast iron, while the low alloyed steel remains practically undeformed. The early (premature) plastifiation of the cast iron leads to a radial expulsion of the base structure associated with a continuous transport of the graphite nodules in the joint plan. As a result, a new graphite film forms which hinders a metallic contact between the parts and a welded joint.
Qualitative and quantitative electron microscopy observations reveal carbon and alloying elements diffusion phenomena on the interface of the dissimilar materials to be joined.
Microstructure of Bonding Interface in Explosively Welded Metal/Ceramic Clad
Authors: Ii Seiichiro , Iwamoto Chihiro , Satonaka Shinobu , Hokamoto Kazuyuki , Fujita Masahiro
Published: January 2010

Bonding interface in aluminum (Al) and silicon nitride (Si3N4) clad fabricated by explosive welding has been investigated by transmission electron microscopy (TEM). The nanocrystalline region was clearly observed at the interface between Al and Si3N4. Electron diffraction pattern and energy dispersive X-ray spectroscopy (EDS) measurements across the interface revealed that this nanocrystalline region consist of the only aluminum.
Three-Dimensional Characterization of Fatigue Crack Propagation Behavior in an Aluminum Alloy Using High Resolution X-Ray Microtomography
Authors: Zhang Hui , Qu Peng Cheng , Sakaguchi Yuuji , Toda Hiroyuki , Kobayashi Masakazu , Uesugi Kentaro , Suzuki Yoshio
Published: January 2010

Synchrotron X-ray microtomography was used to investigate the three-dimensional fatigue crack propagation behavior of an aluminum alloy. Local crack growth rates along specimen thickness were calculated. Crack observation revealed that crack propagation was retarded in three regions where there exist overlapping crack segments. Crack growth retardation was found to occur in these crack overlapping regions due to stress shielding. Observation of crack propagation process indicated that one of the overlapping crack segments initiated from the twisted crack. Crack tip opening displacement was measured and it was found that crack opening was larger in single planar crack region than that in crack overlapping region.
Effect of Plastic Anisotropy on the Predictive Capacity of Flaw Assessment Procedures
Authors: Alexandrov Sergei
Published: January 2010

The limit load is an essential input parameter of flaw assessment procedures. The present paper deals with an effect of plastic anisotropy on its value. An upper bound solution for three-dimensional deformation of a highly under-matched welded specimen subject to tension is proposed. The base material is assumed to be rigid, and the weld material obeys Hill’s quadratic yield criterion for orthotropic materials. It is demonstrated that it is crucial to account for both plastic anisotropy and three dimensionality of deformation in limit load calculations for flaw assessment procedures.
Study on Very High Cycle Fatigue Fracture of High Strength Steel with CFB/M Complex Microstructure
Authors: Yu Y. , Bai B.Z. , Gu Jia Lin
Published: January 2010

The influence of production conditions and Nb microalloy on the very high cycle fatigue (VHCF) behaviors of different Carbide-free bainite/martensite (CFB/M) steels was studied, which include steels produced in laboratory and steelworks. Results show the Nb-microalloy can strengthen the microstructure including the soft bainite plate and improve the VHCF property evidently. In addition, the high purity of steels can avoid inclusion induced crack initiation, but can not improve the VHCF property unless the microstructure possesses favorable uniformity. The critical inclusion size is suggested to be 10-15μm and the CFB/M complex microstructure may be less sensitive to inclusions than other high strength steels.
Failure Analysis of a Hammer Drill Shaft under Complex Loading Paths and Severe Environmental Conditions
Authors: Manohar Priya A.
Published: January 2010

This paper describes the failure investigation of a tubular shaft that is part of a hammer drill assembly. The failure investigation was particularly challenging as the fracture surfaces were completely damaged during and subsequent to the failure process. However, careful examination of the component and its assembly revealed many clues that pointed to the root causes of failure. It was determined that the shaft was subjected to impact, fatigue, bending and torsional loads simultaneously at elevated temperatures. The basic failure mode was identified as a combination of torsional fatigue and rotating bending fatigue failure that originated on the inside diameter of the shaft. The root causes were determined to be operational overload in combination with rough machining marks on the bore surface and higher than necessary operating torque required to overcome the dry adhesive friction in the system. The preventative measures recommended were many-fold including improving surface finish on the bore diameter, reducing dry sliding friction, decreasing the overall level of dynamic loads by appropriate design changes and adding a surface strengthening heat treatment
The Dual Nature of Precipitates in Al-Mg-Si Alloys
Authors: Andersen Sigmund J. , Marioara Calin D. , Vissers René , Torsæter Malin , Bjørge Ruben , Ehlers Flemming J.H. , Holmestad Randi
Published: January 2010

Precipitates in Al-Mg-Si-(Cu) alloys all contain a similar hexagonal arrangement of Si-atoms. Precipitates come and go but their inner Si ordering appears to vary little throughout the precipitation process. In order to improve understanding of precipitation and the related material properties, it is becoming increasingly clear that this includes a good understanding of the hexagonal Si-network, its relation to the precipitates and the Al matrix. Previous studies have revealed that adding Cu atoms to the ternary system, causes the Si network to twist slightly in the matrix about its hexagonal axis, favoring different precipitates. Here we investigate these two rotations. It is shown they can be viewed as a mirror of the network itself about a {310} Al plane. Since precipitates are coherent, the Si-network with its triangular arrangements of Si must also match a fourfold arrangement of Al on the {100} planes. Sets of Al lattice positions exist which can approximate the tree-fold Si symmetry, according to the experimentally observed orientations, and one or more large super-cells can be found having near fit in both lattices. The mirror plane is a main plane in one such super-cell. We show that the mirror leaves every seventh node of the network unchanged, thus defining a smaller hexagonal super-cell in the network, similar to the B’ or Q’/Q phase, where corners are invariant, but where the Si contents is flipped.
Grain Boundary Pinning by Particles
Authors: Rios Paulo Rangel , da Fonseca Gláucio Soares
Published: January 2010

Grain boundary pinning by particles is widely used to prevent grain growth during heat
treatment in a variety of commercial alloys. Its practical relevance is matched by a considerable
amount of theoretical work that has been devoted this problem. A key issue of boundary pinning is the
particle/interface interaction mechanism and its associated pinning force. According to Ashby et al. an
interface may interact with a particle in two ways: either it goes through the particles or, more usually,
bends round and envelopes the particle. Based on these mechanisms one may derive quantitative
expressions relating the characteristics of the particle dispersion and a critical or limiting grain radius.
Thus, Zener expression assumes that the interface goes through the particles whereas Rios expression
assumes that the interface bends round and envelopes the particle. Both the mechanisms and the
resulting expressions are discussed here in detail and compared with available experimental data.
Friction Stir Welding of Magnesium Alloys under Different Process Parameters
Authors: Bruni Carlo , Buffa Gianluca , Fratini Livan , Simoncini M.
Published: January 2010

Experimental and numerical investigations have been performed in order to study the effect of welding parameters on properties of FSW-ed AZ31 magnesium alloy sheets. The results, presented in terms of tensile strength and numerical field variables distributions, allow to understand the behaviour of such material when FSW-ed using different rotational and welding speeds for a given tool geometry.
System for Process Analysis and Hardness Prediction when Quenching Axially-Symmetrical Workpieces of any Shape in Liquid Quenchants
Authors: Liščić Božidar
Published: January 2010

A new Temperature Gradient System has been designed for practical use when quenching real workpieces in any kind of liquid quenchants. The main hardware component of the system is a cylindrical probe of 50 mm Dia. × 200 mm assembled with three thermocouples, and the tem-perature data acquisition unit for automatic drawing of cooling curves. The accompanying software-package consists of three modules: The first one for calculation of the heat transfer coefficient, the second one for quenching process analysis by graphical presentation of different thermodynamic functions, and the third one for hardness distribution prediction on the axial section of axially-symmetrical workpieces of any complex shape. The hardness prediction 2-D program is based on a Finite Volume Method, by which cooling curves in every particular point of the axial workpiece section are calculated, and cooling times from 800 °C to 500 °C (t8/5) determined. Using the known relation between the cooling time (t8/5) and the distance from the quenched end of the Jominy spe-cimen, for the relevant steel, the hardness can be predicted, at once, in every particular point of the axial workpiece section, which is the unique feature of this system. The system itself is designed to: record, evaluate and compare real quenching intensities during the whole quenching process, when different liquid quenchants with different conditions are used, and different quenching techniques have been applied.
The Mechanical Properties of AA2024 as Function of the Interrupted Ageing Conditions
Authors: Risanti D.D. , Yin M. , Chen Jiang Hua , van der Zwaag Sybrand
Published: January 2010

A comprehensive and systematic study using hardness, tensile test and Kahn tear test was undertaken to follow property development during the recently promoted interrupted ageing treatment. In contrast to the reported claims hardness remains lower than that of single stage heat treatment. Toughness does not improve substantially and deteriorates further as re-ageing time is prolonged. For most cases, the effect of interrupted ageing could not produce a simultaneous improvement in mechanical properties. TEM observations indicate the size and distribution co-existing S” and S phases upon re-ageing depend on interrupted condition.
Change in Hardness Statistics during Isothermal Annealing of Cold-Rolled Aluminum
Authors: Yukimoto Tsuyoshi , Utsunomiya Hiroshi , Sakai Tetsuo
Published: January 2010

1050 aluminum sheet was cold-rolled by 50% with mineral oil. Hardness was measured on longitudinal section through the thickness of the rolled sheet. The overall hardness statistics of the as-rolled sheet followed the normal (Gaussian) distribution. Though the sheet was rolled under good lubrication, considerable redundant shear deformation was introduced beneath the surfaces by friction. The layers beneath the surfaces showed higher hardness than the center. The hardness subset statistics in one layer in the thickness also followed normal distribution. Isothermal changes in Vickers hardness statistics and in tensile properties during annealing at 548K were investigated. Beneath the surfaces, the recrystallization initiated and completed earlier than the center. The fully recrystallized sheet also shows the normal distribution of hardness, however the standard deviation is much smaller than that before annealing. The layers beneath the surfaces show lower hardness than the center after recrystallization. The partially recrystallized sheet shows bi-modal distribution of hardness. The partially recrysrallized sheet shows slightly better tensile-elongation balance than both the as-rolled sheet and the sheet-fully recrystallized.
Phases and Structure Characteristics of the Near Eutectic Al-Sl-Cu Alloy Using Derivative Thermo Analysis
Authors: Dobrzański Leszek Adam , Krupiński Mariusz , Labisz Krzysztof , Krupinska Beata , Grajcar Adam
Published: January 2010

For determining of the micro-structural changes taking place in a near eutectic Al-Si-Cu aluminium cast alloy during heating and cooling process the UMSA device (Universal Metallurgical Simulator and Analyzer) was used. In this work the dependence between the regulated cooling speed and structure on the basis of the thermo-analysis was carried out. The thermal analysis was performed at a cooling rate in a range of 0,2 °C to 1,25 °C. The changes were examined and evaluated qualitatively by optical and electron scanning microscopy methods and the EDS microanalysis. During the investigation the formation of aluminium reach (α-Al) dendrites was revealed and also the occurrence of the α+β eutectic, the ternary eutectic α+Al2Cu+β, as well a iron and manganese containing phase was confirmed. The performed investigation are discussed for the reason of an possible improvement of thermal and structural properties of the alloy. The achieved results can be used for liquid metal processing in science and industry – for example foundry for developing and obtaining of a required alloy microstructure and properties influenced by a proper production conditions.
Anisotropy of Bending Properties in Industrial Heat-Treatable Extruded Aluminium Alloys
Authors: Snilsberg Knuter E. , Westermann Ida , Holmedal Bjørn , Hopperstad Odd Sture , Langsrud Y. , Marthinsen Knut
Published: January 2010

In the present work, three-point bending tests have been performed on four commercially extruded 6xxx- and 7xxx alloys, one with a fibrous and one with a recrystallized grain-structure for each alloy class, with the bending axis orientated 0, 45 and 90° with respect to the extrusion direction. Microstructure and texture characterization as well as tensile testing of the same materials have been performed and correlated with the bending results. In general there is good agreement between the bending angle and the fracture strain for all alloys, with the highest values in the extrusion direction. However, there are no indications in the microstructure and texture that explain the large differences in bendability observed. Die lines and recrystallized layer on a fibrous alloy have been removed to investigate their effect on the bending behaviour. However, these effects also seem to be limited, and cannot explain the anisotropy effects observed in bending angles.
Cyclic Deformation Behaviour and Damage Development on Different Hierarchical Levels in Cortical Bone
Authors: Fleck Claudia
Published: January 2010

Bone is a complex natural composite material built of organic and anorganic components and very well adapted to the in vivo loading conditions. The material exhibits an excellent damage resistance under static and fatigue loading conditions. This is partially due to self-healing processes, but to a great extent also to its hierarchical microstructure.
The investigation of the deformation behaviour and the damage mechanisms on different length scales gives valuable insight into which level(s) of hierarchy influence the fatigue resistance in which way. In the present work, cyclic deformation tests have been performed on cortical bone specimens. On one hand, stress-strain-hysteresis measurements in different types of tests, such as constant amplitude tests, load increase tests, and combined static and cyclic tests, give information on the active damage mechanisms. For example, changes in the development of the stiffness, non-elastic strain amplitude and non-elastic mean strain as a result of different loading velocities and stress levels allow the discrimination between time and cycle dependent damage mechanisms. These results were correlated with microstructural investigations of the damage development on different hierarchical levels by light and scanning electron microscopy.
Use of Chitosan as a Material Stabilizer for Acidic Polysaccharides
Authors: Chen Po Hui , Kuo Ting Yun , Wang Da Ming , Lai Juin Yih , Hsieh Hsyue Jen
Published: January 2010

Chitosan was used in this study to form polyelectrolyte complex (PEC) with water-soluble acidic polysaccharides, including gum arabic and pectin. Porous membranes made of gum arabic or pectin only were quiet fragile. After incorporating with chitosan, the usability of the membranes was greatly improved. The results showed that the gum arabic/chitosan composite membranes had detectable tensile stress and elongation capability. Moreover, the pectin/chitosan composite membranes had significantly improved tensile stress and elongation capability. Both of the two composite membranes had greater water uptake capability than the membranes composed of chitosan only. We have demonstrated that chitosan can function as a material stabilizer to maintain the solid status of the acidic polysaccharides and thus improve the performance of these acidic polysaccharides.
Orientation of Biological Apatite in Rat Calvaria Analyzed by Microbeam X-Ray Diffractometer
Authors: Ishimoto Takuya , Sakamoto Tatsushi , Nakano Takayoshi
Published: January 2010

A microbeam X-ray diffractometer is a powerful tool to analyze oriented biological apatite (BAp) crystallites in bones since BAp orientation is one of the dominant controlling factors for bone mechanical function. The formation of BAp orientation seems to be partly affected by the bone formation process, including membranous or intracartilaginous ossification, the direction and the rate of bone growth, the mineral apposition rate, etc. However, the detailed process and the mechanisms of the organization of BAp orientation during the bone formation process are still not understood. In this study, we focused on a calvarial bone as a flat bone to establish a procedure to analyze BAp orientation in calvarial bone and examined the variation in BAp orientation with age and position in growing rats.
Microbeam X-ray diffraction analysis was performed on the extracted calvaria of 5- to 10-week-old Wister rats. The transmission optical system was selected to analyze the orientation of the BAp c-axis along the bone surface. An incident molybdenum (Mo)-K X-ray, which was collimated into a 300-m diameter, was vertically radiated on the calvaria surface, and the diffraction pattern was registered on an imaging plate. Diffraction peak intensities from the (002) and (310) planes of the hexagonal BAp were detected, and then an intensity ratio of (002)/(310) was calculated to evaluate the degree of BAp orientation.
BAp orientation in a calvarial bone was successfully analyzed, and the two-dimensional distribution of the BAp c-axis along the calvarial bone surface was identified. A parietal bone, which is a part of the calvarial bone, showed a unique two-dimensional distribution of the BAp c-axis. The distribution remarkably changed depending on the position on a parietal bone and age. The anisotropy in the preferred BAp orientation was very significant at a region that showed high growth rate. Even though the bone formation process seems to affect BAp orientation in the parietal bone, further investigation is needed to understand the mechanism for the development of BAp texture, which is closely related to bone mechanical function.
Effect of Quenching and Reheating on Isothermal Phase Transformation in Ti-15Nb-10Zr Alloy
Authors: Kobayashi Sengo , Ohshima Ryoichi , Nakai Kiyomichi , Sakamoto Tatsuaki
Published: January 2010

Isothermal phase transformation in Ti-15Nb-10Zr (at%) alloys has been examined by mainly means of transmission electron microscopy. Specimens solution-treated at 1000°C in  phase field were directly held at temperatures between 350 and 450°C for 1.8-86.4ks, which are called "DH (direct holding)-specimen". On the other hand, some specimens solution-treated at 1000°C were quenched into iced brine and then aged at temperatures between 350 and 450°C, which are called "QA(quench and aging)-specimen". In the DH-specimen held at 400°C α phase formed in β matrix. Microstructure evolution of QA-specimen aged at 400°C, on the other hand, is as follows.  phase formed in β matrix after aging for 1.8ks and further aging led to growth of  phase. After prolonged aging, α phase started to form in β matrix. These experimental results indicate that process of the quenching and reheating promotes the formation of  phase. Specimen quenched into iced brine after solution treatment exhibited α'' phase formation. The α'' phase in the quenched specimen would transform into β phase during reheating to the aging temperature. Reversion process of α''  β phase could promote the formation of  phase in β. Microstructure formation in the DH- and QA-specimens at 350 and 450°C will also be explained.
A Dual Role of Copper on the Surface of Bone Implants
Authors: Lüthen Frank , Bergemann Claudia , Bulnheim Ulrike , Prinz Cornelia , Neumann Hans Georg , Podbielski Andreas , Bader Rainer , Rychly Joachim
Published: January 2010

To stimulate bone regeneration, the design of bioactive implants is a great challenge in current orthopedic research. We reasoned that implants should be suitable both to stimulate osteogenic differentiation of mesenchymal stem cells and prevent infections at the site of implantation. Therefore, we focus on copper ions, which are known to exert antimicrobial effects. On the other hand, copper is essential for the cell physiology, including the formation of the extracellular matrix. We studied the influence of copper ions on mesenchymal stem cells at various concentrations and identified the limits of copper concentrations for cell survival. Below the critical concentration for cell survival we analysed proliferation and osteogenic differentiation of the cells in the presence of copper ions. We found that copper stimulated the proliferation of the mesemchymal stem cells at 0.1 mM. Osteogenic differentiation decreased after 14 days at a concentration of 0.05 - 0.1 mM copper ions in osteogenic medium measured by the expression of osteogenic proteins, like alkaline phosphatase (ALP), bone sialoprotein (BSP) and collagen I (COL). We argue that at the implant surface a higher concentration of copper could prevent biofilm formation of bacteria and physiological concentrations in the vicinity of the implant would stimulate stem cell expansion. Together, copper is an interesting agent to control both bacteria and stem cells in the field of implant technology.
From Medicinal Chemistry to Functionalized Biomaterials: Development of Graftable RGD-Peptitomimetics for Cell Adhesion and Cell Addressing
Authors: Marchand-Brynaert Jacqueline
Published: January 2010

Arg-Gly-Asp (RGD) peptidomimetics constructed on the tyrosine scaffold were equipped with an oligoethylene glycol (OEG) spacer-arm for surface grafting. Their in vitro activities as V3 integrin antagonists were in the range of 0.3-0.7 nM. Poly (ethylene terephthalate) (PET) membranes derivatized with peptidomimetics (50-120 pmol/cm2) allowed the adhesion and proliferation of endothelial cells (HSV) in serum-free medium. Iron oxide particles for MR Imaging grafted with peptidomimetics (2-3 molecules/particle of 20 nm diameter) were selectively targeted to activated tumour cells (Jurkat).
Fatigue and Fretting Fatigue Behavior of Metallic Biomaterials
Authors: Maruyama Norio
Published: January 2010

A fretting fatigue test method in a simulated body fluid is shown to evaluate fatigue properties of metallic materials which are used in the orthopaedics field. Next, fatigue/fretting fatigue behavior in a simulated body fluid is given for 316L stainless steel, Ti-6% Al-4% V alloy, pure Ti for industrial use and Co-Cr-Mo alloy. Finally, we discuss the relationship between the tensile strength and the fatigue strength/fretting fatigue strength of metallic biomaterials at 107 cycles in air and in a simulated body fluid. For all of the biomaterials tested, the fatigue strength at 107 cycles is similar in air and in a simulated body fluid. The fatigue strength is closely correlated to the tensile strength: The fatigue strength increases with increasing tensile strength. However, a correlation is not observed between the fretting fatigue strength at 107 cycles and the fatigue strength or the tensile strength.
Recent U.S. FDA Reclassification on the Regulation of Tissue Adhesives for Skin Approximation in Clinical Applications
Authors: Mattamal George J.
Published: January 2010

Since the Medical Device Amendments of 1976 were enacted, the FDA considers Tissue Adhesives as “Transitional Devices” that are classified as Class III medical devices and are marketed in the United States subsequent to the approval of a Pre-market Approval Application (PMA). On February 9, 2006, Regulatory & Clinical Research Institute, Inc. submitted a petition to FDA to reclassify tissue adhesive transitional medical devices for skin approximation from Class III to Class II (special controls). FDA consulted with the General and Plastic Surgery Devices Advisory Panel, and on August 25, 2006, in a public meeting, the panel unanimously recommended that the tissue adhesive transitional medical devices for topical approximation of skin be classified from class III into Class II. Consequently, since June 30, 2008, following the effective date of the FDA Final Rule [1] that reclassified tissue adhesive transitional medical devices for skin approximation, any firm submitting a Premarket Notification [510(k)] for a tissue adhesive for the topical approximation of skin will need to address the issues covered in the published “Class II Special Control Guidance Document: Tissue Adhesive for the Topical Approximation of Skin, dated May 30, 2008” [2]. Accordingly, the firm needs to show that its device meets the recommendations of the published Class II guidance document or in some other way provides equivalent assurances of safety and effectiveness. Also, the author provides a short regulatory description of US FDA, under what laws its operates, how FDA evaluates new medical devices for marketing as Class I, Class II, and Class III [3].
Osteoblast Sensitivity to Topographical and Chemical Features of Titanium
Authors: Nebe Barbara , Jesswein Henrike , Weidmann Arne , Finke Birgit , Lange Regina , Beck Ulrich , Schröder Karsten
Published: January 2010

The titanium-osteoblast-interaction can be influenced both by surface roughness and by chemical modifications. We have ascertained that a positively charged titanium surface boosts osteoblast cells adhesion due to their negatively charged cellular hyaluronan coat. In current experiments, chemical surface modifications were combined with different topographies. Titanium disks of technical purity were modified (i) in their roughness by polishing (P), machining (M) and corundum blasting (CB), and (ii) by subsequently chemical functionalization by a thin film (d≤0.1 µm) of microwave plasma polymerized allylamine (PPAAm). In addition, collagen I was immobilized on PPAAm via the bifunctional linker polyethylene glycol diacid or glutar dialdehyde, respectively. The cell shape and material's contact of human osteoblasts was analyzed by FE-SEM and time dependent cell adhesion measured by flow cytometry. The cell dynamic of the adhesion component vinculin was observed in living cells. Amino-functionalization (PPAAm) considerably enhances the adhesion of osteoblasts in combination with topographical features, which was in contrast to collagen modified surfaces. PPAAm allows the cells to literally melt into the groove structure of the titanium. The bone cells lie over a large area and very close to the surface, so that the edges of the cells can hardly be distinguished from the structure of the surface. The combinatory effect of topography and plasma modification could improve bonding of the implant to the bone tissue.
Structural Analysis of Hydroxyapatite Sinters with Addition of ZrO2 Phase
Authors: Dudek Agata , Nitkiewicz Zygmunt
Published: January 2010

A range of benefits of implants containing hydroxyapatites results, among other things, from their phase composition and degree of porosity. Poor mechanical properties of hydroxyapatite (HA) ceramics considerably limit its wider use. One of the methods for improvement of poor HA properties is addition of solid solution of Y2O3 in ZrO2. [1-8]. The investigations focused on compositions of ceramic powders based on hydroxyapatite with addition of zirconium dioxide (ZrO2 + 8%wt. Y2O3 and ZrO2 + 20%wt. Y2O3). The powders were axially compacted and then sintered at the temperature of 13000C for two hours. After the process of sintering the samples were subjected to analysis of microstructure, phase composition and geometrical measurements in order to determine volume density in each sample.
Comparison of the Cross Sectional Area, the Loss in Volume and the Mechanical Properties of LAE442 and MgCa0.8 as Resorbable Magnesium Alloy Implants after 12 Months Implantation Duration
Authors: Thomann Martina , von der Höh Nina , Bormann Dirk , Rittershaus Dina , Krause C. , Windhagen Henning , Meyer-Lindenberg Andrea
Published: January 2010

Current research focuses on magnesium based alloys in the course of searching a resorbable osteosynthetic material which provides sufficient mechanical properties besides a good biocompatibility. Previous studies reported on a favorable biocompatibility of the alloys LAE442 and MgCa0.8. The present study compared the degradation process of cylindrical LAE442 and MgCa0.8 implants after 12 months implantation duration. Therefore, 10 extruded implants (2.5 x 25 mm, cross sectional area 4.9 mm²) of both alloys were implanted into the medullary cavity of both tibiae of rabbits for 12 months. After euthanization, the right bone-implant-compound was scanned in a µ-computed tomograph (µCT80, ScancoMedical) and nine uniformly distributed cross-sections of each implant were used to determine the residual implants´ cross sectional area (Software AxioVisionRelease 4.5, Zeiss). Left implants were taken out of the bone carefully. After weighing, a three-point bending test was carried out. LAE442 implants degraded obviously slower and more homogeneously than MgCa0.8. The mean residual cross sectional area of LAE442 implants was 4.7 ± 0.07 mm². MgCa0.8 showed an area of only 2.18 ± 1.03 mm². In contrast, the loss in volume of LAE442 pins was more obvious. They lost 64 % of their initial weight. The volume of MgCa0.8 reduced clearly to 54.4 % which corresponds to the cross sectional area results. Three point bending tests revealed that LAE442 showed a loss in strength of 71.2 % while MgCa0.8 lost 85.6 % of its initial strength. All results indicated that LAE442 implants degraded slowly, probably due to the formation of a very obvious degradation layer. Degradation of MgCa0.8 implants was far advanced.
In Situ Hardening Biodegradable and Malleable Polymer-Nanoapatite Composites
Authors: Berger Stefan , Weisser Jürgen , Müller Eberhard , Schnabelrauch Matthias
Published: January 2010

Composite systems composed of nanocrystalline apatites and oligolactide-based polymer networks were prepared resulting in malleable and even injectable formulations which can be cured to compact materials at body temperature. Porous devices with inter-connective porosity were obtained after addition of suitable foaming agents to the composite mixtures. Setting time, porosity and mechanical properties of the composites can be properly adjusted by varying the educt composition. The determined compressive strengths and Young’s moduli of the porous composites perfectly match the mechanical characteristics of cancellous bone material. Preliminary in vitro cell culture experiments with compact composite materials demonstrated their good cytocompatibility. Based on these findings, the synthesized nano-structured composites represent promising candidates for the development of new biomaterials usable in hard tissue regeneration.
Gas-Discharge Plasma-Assisted Functionalization of Titanium Implant Surfaces
Authors: Schröder Karsten , Finke Birgit , Polak Martin , Lüthen Frank , Nebe Barbara , Rychly Joachim , Bader Rainer , Lukowski Gerold , Walschus Uwe , Schlosser Michael , Ohl Andreas , Weltmann Klaus Dieter
Published: January 2010

A crucial factor for in-growth of metallic implants in the bone stock is the rapid cellular acceptance whilst prevention of bacterial adhesion on the surface. Such contradictorily adhesion events could be triggered by surface properties. There already exists fundamental knowledge about the influence of physicochemical surface properties like roughness, titanium dioxide modifications, cleanness, and (mainly ceramic) coatings on cell and microbial behavior in vitro and in vivo.
The titanium surface can be equipped with antimicrobial properties by plasma-based copper implantation, which allows the release and generation of small concentrations of copper ions during contact with water-based biological liquids.
Additionally, the titanium surface was equipped with amino groups by the deposition of an ultrathin plasma polymer. This coating on the one hand does not significantly reduce the generation of copper ions, and on the other hand improves the adhesion and spreading of osteoblast cells.
The process development was accompanied by physicochemical surface analyses like XPS, FTIR, contact angle, SEM, and AFM. Very thin modified layers were created, which are resistant to hydrolysis and delamination. These titanium surface functionalizations were found to have either an antimicrobial activity or cell-adhesive properties. Intramuscular implantation of titanium samples coated with the cell-adhesive plasma polymer in rats revealed a reduced inflammation reaction compared to uncoated titanium.
Enhanced Macro and Micro Stress Evaluation Diffraction Techniques Applied to Biomedical Materials
Authors: Sprauel Jean Michel
Published: January 2010

Residual stress has large effect to the service life of biomedical ceramic coatings. It is therefore important to characterize it precisely. Since in-service damage of the prostheses is generally characterized by cracking of the substrate layers located close to the metal / ceramic interface, our study was focused on these particular zones of the parts. High energy synchrotron radiation diffraction techniques were therefore developed to evaluate the residual stress profiles of the metal / ceramic interfaces. The method requires, however, defining precisely the true position of the X-ray probe inside the materials. A complete modeling of the instrument, using a ray tracing Monte Carlo simulation method, was developed for that purpose. Fourier analysis of the diffraction peaks was also implemented to evaluate the micro stresses of second and third kind. These diffraction techniques were tested on a glassy ceramic coating used for the manufacturing of dental prostheses.
Selenium Nanocluster Coatings: Transforming Current Orthopedic Materials into Inhibiting Bone Cancer
Authors: Tran Phong A. , Sarin Love , Hurt Robert H. , Webster Thomas J.
Published: January 2010

Selenium (Se) nanoclusters were coated on three different orthopedic materials: Titanium, stainless steel and ultra high molecular weight polyethylene (UHMWPE). There different coating densities were achieved on each type of substrate. The uncoated and coated Ti and SS substrates were then used in experiments with either normal healthy osteoblasts (bone-forming cells) or cancerous osteoblasts (osteosarcoma) or a combination of both. For the first time, it was shown that the substrates coated with Se nanoclusters promoted (or at least maintained) normal osteoblast proliferation and inhibited cancerous osteoblast growth in both separate culture experiments and co-culture experiments. Thus, this study introduced to the orthopedic cancer community for the first time a coating material (Se) which may inhibit bone cancer growth and promote normal bone growth.
Dielectric Properties in Fresh Trabecular Bone Tissue from 1MHz to 1000MHz: A Fast and Non Destructive Quality Evaluation Technique
Authors: Irastorza Ramiro M. , Valente Sergio , Vericat Fernando , Blangino Eugenia
Published: January 2010

The increasing research on development of novel bio-materials has resulted in several studies on non-destructive evaluation methods for characterizing these materials and the biological materials receiving them. A broad range of techniques are available. As an alternative tool, electrical impedance spectroscopy, has become a widely used, non destructive and low cost technique in material quality evaluation. Particularly in bones, it has also been demonstrated that mechanical characteristics are strongly correlated to dielectric properties. In this work, non destructive estimation (the same samples can be tested using other techniques) of the dielectric properties of fresh trabecular bones (layered lossy structure) using coaxial probes is analyzed from 1MHz to 10MHz (in frequency domain) and from 80MHz to 1GHz (in both, frequency and time domain). Frequency domain system identification is used to build the estimation in the low frequency range and an orthonormal based identification approach, for the high frequency data. Comments on conductive samples, non Debye dielectrics and polarization effects are added. The methodology was applied to a particular human sample population of aged adult femur heads and results are presented here. A comparison with destructive test, in which the samples were machined into cylinders of 7mm diameter, is also performed.
Microstructural and Mechanical Characterization of Gray Cast Iron and AlSi Alloy after Laser Beam Hardening
Authors: Monteiro Waldemar Alfredo , Silva E.M.R. , Silva L.V. , de Rossi W. , Buso S.J.
Published: January 2010

A localized source of heat, such as that of laser beam, can provide a convenient means of producing a surface layer of altered microstructure. By using surface hardening treatment, wear resistance can be increased. Experiments were performed using a Nd:YAG pulsed laser under different processing conditions. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray mapping (SEM) were employed to observe the effect of laser melting treatment on the microstructural properties of the samples. Depending on the selected laser treatment working conditions, different microstructures characteristics of surface melting can be achieved in the treated zone. Higher microhardness values were found at the treated area showing a superficial hardening of the sample and, consequently, an improvement of the wear resistance of these automotive alloys. The aim of this work is to find the optimal process parameters and to evaluate the characteristics of the laser superficial hardening (LSH) in a pearlitic gray iron and Al-Si alloy used in an automobile industry (bearing and piston materials in automotive industry).
Shot Peening of Brittle Materials - Status and Outlook
Authors: Pfeiffer Wulf , Wenzel Johannes
Published: January 2010

Shot peening is a common procedure to improve the static and cyclic strength of metal components by a combination of work hardening and the introduction of compressive stresses into the surface region. Our investigations through the last years showed that high compressive stresses of more than 1 GPa can also be introduced in brittle ceramics under specific shot peening conditions. These stresses significantly increase the near-surface strength. Based on the findings for ceramics, shot peening procedures have now been developed for cemented carbides and hard chromium platings. Recent investigations showed that, due to the higher fracture toughness of cemented carbides, shot peening could be performed using higher peening intensities leading to a higher gain in strength properties. Although chromium platings are less brittle than ceramics, shot peening of these layers are very challenging due to the formation of a micro-crack network being typically for these coatings. Nevertheless, first results indicate the possibility of a successfully shot peening of these coatings.
Ceramic Target Materials for Sputtering Applications
Authors: Simons Christoph , Kastner Albert , Kiriakidis George
Published: January 2010

The lecture will give an overview of the manufacturing technique of ceramic target materials based on ZnO and TiO2. Sintering and plasma spraying techniques are typically used. Also special bonding procedures have to be established in order to join ceramic target materials to metallic carriers. Metallic and ceramic target materials will be compared with respect to target materials processing and sputtering experiences as well. In addition planar and cylindrical targets will be briefly discussed as sputtering of large substrates is strongly moving towards cylindrical cathode applications.
Effect of Plasma Treatment on Adhesion of DLC Layers to Steels
Authors: Tillmann Wolfgang , Vogli Evelina , Momeni Siavash
Published: January 2010

Diamond like carbon layers play a key role in industrial applications. However the layers quality deteriorates often due to insufficient interfacial adhesion. In this research work a prior plasma treatment of steel substrates was employed aimed to improve the interfacial adhesion of DLC-layers to steel substrates. Three different kinds of steels were employed and their microstructures as well as their compositions before and after plasma treatment were analyzed. The interfacial adhesion of DLC layers on the non-nitrided and nitrided steels was observed and the influence of the steel microstructure on the interfacial adhesion was studied.
Effects of High Magnetic Field Annealing on the Nucleation Sites for Recrystallized Nuclei with {111} <112> Orientation in Cold-Rolled IF Steel Sheet
Authors: Wu Yan , He Chang Shu , Zhang Yu Dong , Zhao Xiang , Zuo Liang , Esling Claude
Published: January 2010

The effect of high magnetic field annealing on the nucleation sites for recrystallized nuclei with {111}<112> orientation in the initial stage of recrystallization in as-annealed interstitial-free (IF) steel sheet were investigated by the SEM-EBSD analysis. Specimens of cold rolled IF steel sheet were annealed at 650°C for 0min and 10min respectively with a 12-tesla magnetic field to obtain a partially recrystallized microstructure. During the magnetic field annealing, they were respectively placed at the center of the applied field with their rolling planes parallel to the magnetic field direction (MD), and with their rolling direction (RD) parallel and normal to the MD, respectively. It was found that different to the non-field annealed specimen, in the field annealed specimens, the {111}<112> oriented recrystallized nulei favored to nucleate in the {111}<112> deformed matrix and not in the {111}<110> deformed matrix. This phenomenon may be attributed to the magnetic ordered state induced by the magnetic field, which might suppress the formation of high-energy grain boundaries between the newly formed nuclei and the deformed matrix.
Production of Rapidly Solidified Composite Deposits Based on Iron with Vanadium Carbide Particles by Plasma Spraying
Authors: Hoshiyama Yasuhiro , Hirano Kentaro , Miyake Hidekazu
Published: January 2010

In the thermal spraying process, spray material is heated, melted, and accelerated by a high temperature flame. Thermal spraying can produce thick materials that rapidly solidify, because the alloy droplets accumulate successively on the substrate and solidify at a cooling rate in the range of 105-108Ks-1. Depending on the cooling conditions of the substrate and on the alloy composition, deposits are produced with metastable phases or extremely fine crystalline phases. Thermal spraying is an attractive method for the production of composite deposits with fine particles formed in-situ. In particular, iron based alloy with vanadium carbide, is useful in metal molds and also in pump parts due to its high wear resistance and high corrosion resistance. In the present work, low-pressure plasma spraying of Fe-C-V/Ni-Mg and Fe-C-V-Cr-Ni/Ni-Mg blend powders were iron based composite deposits with finely dispersed vanadium carbide particles. The as-sprayed deposit produced from Fe-C-V/Ni-Mg blend powder is composed of αFe and V8C7. The as-sprayed deposit produced from Fe-C-V-Cr-Ni/Ni-Mg blend powder is made up of γFe, αFe, V8C7 and Cr7C3. The fine precipitates of approximately 0.3μm in the as-sprayed deposit are carbide. With increasing the heat-treatment temperature up to 1273K, the carbide particles coarsen. The hardness of as-sprayed deposit produced from the Fe-C-V-Cr-Ni/Ni-Mg, which has many fine carbide precipitates, is the hardest of the deposits.
Wear and Corrosion Resistance of Electroless Nickel-Boron Coated Mild Steel
Authors: Kanta Abdoul Fatah , Vitry Véronique , Delaunois Fabienne
Published: January 2010

Nickel-boron coatings were synthesized on mild steel by the electroless deposition method. Some of the coatings were submitted to a hardening heat treatment at 400°C during 1 hour in an atmosphere containing 95% Ar and 5% H2. Uncoated steel, treated and untreated samples were submitted to the Taber abrasion test to assess their wear resistance. The wear track was then examined by SEM and roughness measurement. The Taber Wear Index of untreated samples was slightly better than that of steel but heat treated samples attained TWI as small as 13. The corrosion resistance of the samples was investigated by the way of polarization and electrochemical impedance spectroscopy (EIS) and the influence of the heat treatment was observed.