bluuebunny/crossref_metadata_2025 huggingface dataset:
Additive Manufacturing of Titanium Parts Using 3D Plasma Metal Deposition
Authors: Hoefer Kevin , Mayr Peter
Published: December 2018

Additive manufacturing of titanium components offers several advantages compared to conventional production technologies such as higher material utilization efficiency and increased geometric possibilities. In comparison to laser powder bed processes, arc-based additive manufacturing processes have the additional advantage of an almost unlimited assembly space, higher deposition rates and an improved utilisation factor of raw materials. Disadvantages of wire-based methods are the restricted availability of different types of wire consumables, the fact that the wire feed rate is directly coupled to the heat input and the lack of possibility to create multi-material structures in-situ.Within this work, the 3D Plasma Metal Deposition (3DPMD) method, based on a plasma powder deposition process is introduced. 3DPMD has some special advantages compared to the established plasma powder process and other additive processes. For example, up to four powders, which can differ in terms of material and powder fraction, can be mixed within one layer. This allows a targeted adaption of local properties (microstructure, mechanical properties, wear resistance, porosity, etc.) to the targeted load type and level. The tailored introduction of reinforcement particles, e.g. tungsten or titanium carbides, into the component is a simple example.The study aims to demonstrate the suitability of the 3DPMD for the production of titanium components in layer-by-layer design. Various demonstrators are prepared and analysed. The microstructures, the porosity and the hardness values of the different structures are analysed.In summary, 3DPMD offers the possibility to produce titanium structures with and without reinforcement particles. Using automated routines, it is possible to generate metallic structures directly from the CAD drawings using welding robots. Microstructures and properties are directly related to the process and, therefore, structure-process-property relationships are discussed within this work.
Significant Benefits of 3D Screen Printing for Manufacturing Micro-Channel Heat Exchangers
Authors: Zess James Allen , Dressler Martin
Published: December 2018

Micro-channel heat exchangers (MCHXs) manufactured by Zess & Lin Industries provide highly effective heat transfer and are used in a growing number of critical applications. MCHXs consist of stainless steel or high temperature Nickel-based alloy plates with micro channels that are chemically etched or machined into each plate. These traditional extractive manufacturing methods of chemical etching and machining used in manufacturing MCHX plates are difficult and costly as a large percentage of expensive alloy is lost during manufacturing.
Design of Additively Manufactured Lattice Structures for Tissue Regeneration
Authors: Lanzotti Antonio , Martorelli Massimo , Russo Teresa , Gloria Antonio
Published: December 2018

Additive Manufacturing technologies allow for the direct fabrication of lightweight structures with improved properties. In this context, Fused Deposition Modelling (FDM) has also been considered to design 3D multifunctional scaffolds with complex morphology, tailored biological, mechanical and mass transport properties. As an example, poly (ε-caprolactone) (PCL), surface-modified PCL and PCL-based nanocomposite scaffolds were fabricated and analysed. The effects of structural and morphological features (i.e., sequence of stacking, fiber spacing distance, pore size and geometry), surface modification and nanoparticles on the in vitro biological and mechanical performances were investigated.
Compositional Optimization of In718 Superalloy Powder for Additive Manufacturing
Authors: Lin Che Yi , Bor Hui Yum , Wei Chao Nan , Liao Chien Hung
Published: December 2018

In this research, a composition optimized In718 superalloy powder suitable for additive manufacturing has been developed by using the vacuum induction melting gas atomization (VIGA) and the powder sieving process. VIGA which combines the vacuum induction melting (VIM) and gas atomization (GA) processes uses high pressure inert gas to atomize the metal melt formed by VIM to form metal droplets. These metal droplets are solidified to form metal powders during the falling process in the atomized chamber. After the sieving process, the mean particle size D50 of the powder is less than 35 μm and the particle size distribution (PSD) ranges from 10 to 55 μm (D10~D90). Besides, the produced powder has high flowability (ICarr ≦15), which is suitable for selective laser melting (SLM) additive manufacturing (AM). After the SLM process, the tensile tests are conducted at room temperature and high temperature of 650°C. The results show that the high temperature properties of the optimized In718 superalloy are superior to the commercial In718 superalloy.
Fabrication and Tailoring Interface Structure of Diamond/Al(and Al12Si) Composites for Heat Sink Applications by Vacuum Hot Pressing and Selective Laser Melting
Authors: Ji Gang , Tan Zhan Qiu , Li Xiao Peng , Li Zhi Qiang , Kruth Jean Pierre
Published: December 2018

Al and Al12Si matrix composites reinforced with synthetic diamond particles have been developed by using conventional powder metallurgy and emerging additive manufacturing techniques, i.e. vacuum hot pressing (VHP) and selective laser melting (SLM), respectively. Relative density and interface structure have been evaluated to relate to measured thermal conductivity (TC) of the composite. Despite very different physical and metallurgical mechanisms (VHP vs. SLM), the diamond/Al interface can be tailored allowing to form a ‘clean’ and tightly-adhered interface at the micrometer scale in both cases. This so-called diffusion-bonded interface is the most favorable for enhancing overall TC which demonstrates the potential of SLM for processing multifunctional Al matrix composites. However, how to realize full densification and simultaneously maintain such an interface structure during SLM remains a key technical problem to figure out.
Three Dimensional Smart Processing by Ultra Violet Laser Lithography of Ceramic Additive Manufacturing
Authors: Nonaka Koki , Kirihara Soshu
Published: December 2018

Additive manufacturing (AM) and three-dimensional printing (3DP) technologies are being developed for use in manufacturing. In this study, a new AM technology, laser stereo-lithography, that enables to fabricate ceramic components in a single process is developed. This method is demonstrated with alumina under various laser conditions.
Hydrogen Release from Oxidized Titanium Hydride
Authors: Gambini Marco , Montanari Roberto , Richetta Maria , Stilo Tommaso , Varone Alessandra , Vellini Michela
Published: December 2018

Hydrogen storage is one of the most important industrial applications of titanium hydride (TiH2). A critical issue is the hydrogen release rate that strongly depends on the surface structure of TiH2 particles. This work reports the results of an experimental campaign carried out on TiH2 powders submitted to heat treatments in air at different temperatures and treatment times. After each heat treatment the TiH2 powders were examined by X-ray diffraction (XRD) and the results evidenced that the surface layer consists of TiO2 and Ti2O. Titanium oxide formation has been monitored by XRD at high temperature. Hydrogen release during heating of oxidized powders was investigated through temperature programmed desorption (TPD). Residual hydrogen in TiH2 depends on the specific treatment: higher temperature and soaking time of the treatment, lower its content.
Increasing the Electrical Conductivity of Layered Double Hydroxides by Intercalation of Ionic Liquids
Authors: Ciotta Erica , Pizzoferrato Roberto , Di Vona Maria Luisa , Ferrari Ivan Vito , Richetta Maria , Varone Alessandra
Published: December 2018

Layered double hydroxides (LDHs) are anionic clays composed by host layers of positively charged metal hydroxide, in which anions are intercalated to neutralize the charge of the positive layers. Because of the positive charge of the structure and because of their properties of anion exchanges, diﬀerent anions can be intercalated into the structure. In recent years the ionic conductivity of LDHs was studied for use as the anode material in lithium-ion batteries or PVA/LDH hybrid membranes for fuel cells. However, such studies have reported very low values of the electrical conductivity that is less than 10-3 S cm-1 near room temperature. However, the ion conductivities of LDHs depends on the intercalated anion species and may be aﬀected by diﬀerence in the synthesis condition. Moreover, the anion conductivity increases with increasing interlayer distance and as more water is adsorbed by LDH. Within this framework, we have intercalated two ionic liquids, tetramethylammonium hydroxide (TMAH) and 1-buthyl-3-methylimidazolium hydrogen sulfate (Bmim-HSO4) in the interlamellar space with the purpose of increasing the ionic conductivity and decreasing the dependence from the water content. LDH was prepared using the co-precipitation method with controlled pH. The introduction of IL was performed by the intercalation methods. The increase of conductivity was around an order of magnitude in the case of Bmim-HSO4. The LDH-IL can be an interesting material to prepare composite membranes for electrochemical applications.
The Influence of Gas Diffusion Media Morphology on Hydrogen Fuel Cell Performance
Authors: Gould Benjamin , Garsany Yannick , Sassin Megan , Atkinson III Robert , Zenyuk Iryna , Swider-Lyons Karen
Published: December 2018

Gas diffusion media (GDM) is an integral part of all gas diffusion electrodes because it facilitates both the transport of reactants to the electrocatalyst surface and the removal of reaction products from the system. Proper reactant/product distribution is critical for high power operation in polymer electrolyte fuel cells (PEMFCs) because oxygen transport and water rejection determine the maximum current density that can be obtained from PEMFCs. This paper will discuss NRL’s research on how GDM morphology influences cell performance in both closed-cathode fuel cell and open-cathode fuel cell designs. The comprehensive study linking the influence of compression on the GDM micro and macro structure morphology will be presented using micro X-ray computed tomography (μ-CT), scanning electron microscopy (SEM), N2 Physisorption (BET) and traditional electrochemical characterization techniques (CV, Pol. Curves, etc.). Optimal GDM selection for the challenge of open-cathode operation will be presented and related to water retention through rational morphology selection. The relationship between high power performance and water transport will be elucidated and the goals for future GDM properties will be proposed for use in unmanned systems
Microstructures and Mechanical Properties of Welded Joints of Several High Tensile Strength Steel
Authors: Izumi Takahiro , Kobayashi Tatsuya , Shohji Ikuo , Miyanaga Hiroaki
Published: December 2018

Microstructures and mechanical properties of lap fillet welded joints of several high and ultra-high tensile strength steel by arc welding were investigated. Steel plates having tensile strength of 400 (SPH400W), 590 (SPC590Y, SPC590R), 980 (SPC980Y) and 1500 MPa (SAC1500HP) class with 2 mm thickness were prepared. Four types of joints were formed by MAG welding; SPH400W/SPH400W, SPC590Y/SPC590Y, SPC980Y/SPC980Y and SAC1500HP/SPC590R. In joints with SPC590Y, SPC980Y and SAC1500HP steel which matrixes are martensitic microstructures, the HAZ softens due to transformation of martensite into ferrite with precipitating cementite. By using high and ultra-high tensile strength steel, the weld metal is strengthened due to dilution of the matrix into the weld metal and thus tensile shear strength of the welded joint increases. In the fatigue test, similar S-N diagrams were obtained in the all welded joints investigated. It seems that the effect of stress concentration due to the shape of the welded joint on fatigue properties is larger than that of the strength of the matrix.
Synthesis of Fluorescent Ag Nanoclusters for Sensing and Imaging Applications
Authors: Burratti Luca , Bolli Eleonora , Casalboni Mauro , de Matteis Fabio , Mochi Federico , Francini Roberto , Casciardi Stefano , Prosposito Paolo
Published: December 2018

Metal nanoparticles have attracted more and more attention in the last years due to their unique chemical and physical properties which are very different from the metal bulk material. In particular, when the size of nanoparticles decreases below two nm, nanoparticles can be described as nanoclusters (NCs), and they present peculiar optical properties. The excited electrons in addition to specific absorption bands show also a bright luminescence related to the quantum size effect which produce discrete energy levels. Optical properties (absorption and fluorescence) of these NCs are widely used in many different applications in science and engineering, such as chemical sensors, fluorescent probes for bio imaging or in environmental issues. In the present study, we report on the synthesis of silver nanoclusters (AgNCs) in aqueous phase using silver nitrate as precursor salt and L-Glutathione (GSH) as stabilizer. AgNCs were characterized using absorption and fluorescence spectroscopy, and transmission electron microscopy (TEM). The strong absorption and luminescence shown by these NCs are very promising for a possible exploitation both as label for bioimaging and for optical sensors for heavy metal ions.
Polymer Interphases in Adhesively Bonded Joints – Origin, Properties and Methods for Characterization
Authors: Geiss Paul Ludwig , Schumann Melanie
Published: December 2018

Chemically curing adhesives are formulations requiring reactions to convert from liquid to solid. Once cured, these adhesives carry the potential to create strong load bearing joints, resisting even severe detrimental service conditions. In adhesively bonded joints with chemically curing adhesives the term "interphase" relates to the adhesive volume adjacent to the surface of the adherent (interface), which generally will exhibit properties different from those of the adhesive bulk polymer. The properties of these interphases play an important role concerning the performance and durability of structural adhesive joints. Therefore localized strain analysis in the cross-section of shear-loaded adhesive joints was performed by combining a high-precision mechanical testing device with digital microscopy and by developing a method for preparing, marking, and digitally tracking the local deformations in micro shear specimen. Non-uniform shear profiles developing in the cross-section of the adhesive joints after exceeding the yield point serve as a sensitive indication for mechanical surface-affected interphase properties and it could be observed, that deranged crosslinking promotes strain softening of the polymer in the interphase. Infrared analysis of the cross-sectional interphase region in adhesively bonded joints was performed with a Bruker Tensor II Fourier Transform Infrared (FTIR) spectrometer equipped with a Hyperion 3000 microscope with a 20x ATR germanium crystal objective and a MCT-Focal-Plane-Array-Detector (FPA), allowing to conduct high resolution chemical imaging and localized chemical analysis.
Energy of Small Angle Tilt Boundary in Al
Authors: Nishitani Shigeto R.
Published: December 2018

The critical inconsistency on the small angle boundary energy between the theoretical prediction of Read-Shockley model and the experimental results was discussed. The plots of the ratio between boundary energy E and the tilt angle θ against log θ show different tendency between the EAM simulated and the experimental results. The first principles calculations on the small angle tilt boundary energy on Al ⟨100⟩ direction were performed. Still the calculation sizes of the model are limited, the obtained values are located between the EAM simulated and the experimetal results.
Structural, Electronic and Mechanical Properties of Perovskite Oxides LaMO3 (M = Mn, Ni) Compounds in the High and Low Symmetric Phases by First Principle Calculation
Authors: Bachir Bouiadjra Oussama , Merad Ghouti , Raulot Jean Marc , Si Abdelkader Hayet , Esling Claude
Published: December 2018

The widely investigated perovskite oxides has attracted for a long time a great interest on the physical properties, in their bulk structures as well as the heterostructures components. The Lanthanum transition metal oxides LaMO3 (M= Transition metal) is part of, due to their potential use in advanced technology (including superconductivity, magnetoresistance, ionic conductivity, and a multitude of dielectric properties). Despite the broad exploration of the physical properties, we found a considerable lack in the investigation of the mechanical properties of the LaMO3 compounds. By applying the Density Functional Theory (DFT), we shed light on the structural, electronic, and especially mechanical properties of the experimentally verified phases of The LaMnO3, and LaNiO3. We first calculated the structural and electronic properties, then we continue with the single-crystal elastic constants and mechanical properties, where the bulk, shear and Young’s moduli, and the Anisotropy indexes were deduced, in order to remedy the existing gap of the theoretical knowledge about the mechanical behavior of the LaMnO3, and LaNiO3 compounds.
Mastering of the Filling Stage in Low Pressure Sand Casting Process
Authors: Sanitas Antonin , Bedel Marie , Khelladi Sofiane , El Mansori Mohamed
Published: December 2018

In Low Pressure Casting (LPC), the counter gravity filling at low velocity and the protective gas atmosphere above the metal can potentially reduce gas and oxides entrapment in the metal. However, the relationship between the imposed gas pressure evolution and the melt filling dynamics cannot be analytically determined as it is geometry-dependent. This issue is the missing link to master and automate the filling step in LPC process. In this work, the filling dynamics is numerically investigated for different mold geometries and pressure ramps. The simulation, carried out using ANSYS Fluent® simulation software, is combined with an analytical model. As the results are quantitatively predictive of the filling flow, it permits to develop a numerical study, considering different sudden or progressive section changes and pressure ramps. The impact of the different process parameters on the flow dynamics is analyzed, particularly the transition smoothing impact.
Ductility and Stability in Metallic Materials
Authors: Ruano Oscar , Carreño Fernando , Carsí Manuel
Published: December 2018

Ductility is the property of a given material to deform without fracture. In other words, is the capacity to maintain a structural stability under stresses. It is an important property that is difficult to predict since many microstructural and experimental factors play a role. A review of the most important approaches on ductility is given in this work with special emphasis in the high temperature deformation and the deformation mechanisms. The stability of materials is also analyzed and new concepts on the conditions for hot working are included. Stability maps are analyzed and conclusions on the various stability criteria are given on the base of magnesium alloys.
Hot Forming Optimization of ZK30 Magnesium Alloy
Authors: Carsí Manuel , Carreño Fernando , Ruano Oscar
Published: December 2018

The modeling of the forming of materials at high homologous temperatures allows obtaining optimum forming parameters, reduced costs and improving final properties of the finished product. In this work, the behavior of the ZK30 Magnesium alloy was characterized by means of compression tests at temperatures 300 to 450oC and strain rates between 0.1 and 8.7 s-1. Using data from these tests, the parameters of the Garofalo equation are calculated. In addition, by means of the second Lyapunov stability criterion, the optimum temperature at a given temperature is determined which should minimize the appearance of deformation bands and cracks during hot working. This temperature was found to be 641 K (368oC) at 8.7 s-1.
Development of an Anti-Trapping Current for Phase Field Models Using Arbitrary CALPHAD Thermodynamics
Authors: Mullis Andrew M. , Bollada Peter C. , Jimack Peter K.
Published: December 2018

Unless corrected by so called anti-trapping currents, phase field models of solidification display a dependence upon the diffuse interface width, δ, used in the simulation. This is most commonly manifest as a reduction in solute partitioning, which is both growth velocity and interface width dependent, resulting in a serious impediment to quantitative simulation. However, such anti-trapping currents are often restricted to very simple materials thermodynamics, appropriate only to dilute ideal solutions. Here we propose a form of the anti-trapping current which can be implemented for arbitrary thermodynamics, including both Redlich-Kister solution phases and sub-lattice models for intermetallic growth. The effect of the new anti-trapping current is illustrated with respect to Pb dendrites growing from a Pb-Sn melt containing either 25% or 30% Sn. The new anti-trapping current is shown to render the solutions independent of the diffuse interface width both with regard to solute partitioning and other growth metrics such as solidification velocity and dendrite tip radius.
VC-Precipitation Kinetics Studied by Small-Angle Neutron Scattering in Nano-Steels
Authors: Ioannidou Chrysoula , Arechabaleta Zaloa , Rijkenberg Arjan , Dalgliesh Robert M. , van Well A.A. , Offerman S. Erik
Published: December 2018

Nanosteels are used in automotive applications to accomplish resource-efficiency while providing high-tech properties. Quantitative data and further understanding on the precipitation kinetics in Nanosteels can contribute to fulfil this goal. Small-Angle Neutron Scattering measurements are performed on a Fe-C-Mn-V steel, previously heat-treated in a dilatometer at 650°C for several holding times from seconds to 10 hours. The evolution of the precipitate volume fraction, size distribution and number density is calculated by fitting the experimental Small-Angle Neutron Scattering curves. The effect of phase transformation on precipitation kinetics is also discussed. Complementary Transmission Electron Microscopy, Scanning Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy measurements are performed to support the Small-Angle Neutron Scattering data analysis.
Wear Behaviour of Two Different Cemented Carbide Grades in Turning 316 L Stainless Steel
Authors: Saketi Sara , Bexell Ulf , Östby Jonas , Olsson Mikael
Published: December 2018

Cemented carbides are the most common cutting tools for machining various grades of steels. In this study, wear behavior of two different cemented carbide grades with roughly the same fraction of binder phase and carbide phase but different grain size, in turning austenitic stainless steel is investigated. Wear tests were carried out against 316L stainless steel at 180 and 250 m/min cutting speeds.The worn surface of cutting tool is characterized using high resolution scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), Auger electron spectroscopy (AES) and 3D optical profiler.The wear of cemented carbide in turning stainless steel is controlled by both chemical and mechanical wear. Plastic deformation, grain fracture and chemical wear is observed on flank and rake face of the cutting insert. In the case of fine-grained, the WC grains has higher surface contact with the adhered material which promotes higher chemical reaction and degradation of WC grains, so chemical wear resistance of the composites is larger when WC grains are larger. The hardness of cemented carbide increase linearly by decreasing grain size, therefore mechanical wear resistance of the composites is larger when WC grains are smaller.
Study on the Statistical Errors in X-Ray Stress Measurement with Two-Dimensional Detector
Authors: Ejiri Shoichi , Ohba Hiroaki , Sasaki Toshihiko
Published: December 2018

The sin2 ψ method [1] is conventionally used well as how to measure non-destructively the residual strain and stress states of polycrystalline materials by X-ray diffraction. In the conventional method, there are Dölle-Hauk method [2] and Winholz-Cohen least squares analysis [3] as the determinations of the strain and stress states for limiting the influence of measurement errors. Many researches are made about the statistical error in those methods. In recent years, use of the X-ray stress measurements with two-dimensional detector from the conventional method is spreading. One of the measurements is called the cos α method. The measurement errors have attracted a great deal of attention for users as the spreads. Therefore, the basic equations and determinations of the strain and stress states are examined. The confidence intervals of measured stress by the cos α method. The research and development is performed for the the cos α method which took the influence of measurement errors into consideration.
Evaluation of Railway Rails Suffered from Rolling Contact Fatigue Using X-Ray Generalized cosα Method
Authors: Sasaki Toshihiko
Published: December 2018

In this study, the diffraction rings were measured point by point all over the head of rail sample which was used in service, and shearing stresses with respect to the depth direction were determined using the generalized cosα method. The full width at half maximum was also estimated from the diffraction ring.
Portable System for the Measure of Efficiency in Arc Welding Processes
Authors: Barbieri Giuseppe , Bifaretti Stefano , Bonaiuto Vincenzo , Cognini Francesco , Moncada Massimo , Montanari Roberto , Pipolo Sabino , Richetta Maria , Varone Alessandra
Published: December 2018

In recent years, the monitoring of the energy consumption in the industrial processes shows a growing interest due to its strong fallout on environmental pollution and environmental sustainability. On this purpose, this paper deals with the design of a portable Digital Acquisition system (DAQ) tailored for monitoring the energy consumption in different classes of welding machines. The proposed system is a multichannel DAQ able to measure the overall power consumption at the input of the machine (including those relative to the secondary equipment present in the welding process as gas pumps, chillers, etc.) together with some other physical quantities in output (which depend on the features own of the welding machine). The results of these measurements will be deeply investigated and, by a proper metallurgical analysis, related to the mechanical characteristics of the welted joint. Some results on preliminary measures performed on a Tungsten Inert Gas (TIG) welding machine in a real industrial welding process will be shown in the paper.
SteBLife – The Enhanced Short-Time Evaluation Procedure for Materials Fatigue Data Generation
Authors: Starke Peter , Wu Haoran , Boller Christian
Published: December 2018

The availability of reliable fatigue data is of continuous and often urgent need. The paper to be presented therefore intends to show how the potential of non-destructive testing methods, digitisation in metrology as well as signal processing can be combined in order to achieve a significant gain in information concerning the fatigue behaviour combined with a reduction of required experimental effort and cost. The new SteBLife approach is an enhanced short-time calculation method developed at the Chair of Non-Destructive Testing and Quality Assurance at Saarland University, which takes into account that a material’s elastic-plastic reaction and hence relationship is non-linear. With respect to a test strategy, the number of fatigue experiments required to determine a material’s complete S-N-curve can be limited to three to five tests only (SteBLifemtc, mtc: multiple tests, trend curve and SteBLifemsb, msb: multiple tests, scatter bands) in cases that mean values and/or complete scatter bands of S-N-curves are required. If a trend S-N-curve is sufficient, the effort can be reduced to one single test only (SteBLifestc, stc: single test, trend curve) with a special step-shaped specimen. This leads to a significant improvement in efficiency when compared to the conventional way an S-N-curve is determined where a minimum of 15 fatigue tests is required. Within the work to be presented the SteBLife method is demonstrated for normalized SAE 1045 (C45E) steel.
Microstructure Characterisation of Advanced Materials via 2D and 3D X-Ray Refraction Techniques
Authors: Müller Bernd R. , Kupsch Andreas , Laquai René , Nellesen Jens , Tillmann Wolfgang , Kapserovich Galina , Bruno Giovanni
Published: December 2018

3D imaging techniques have an enormous potential to understand the microstructure, its evolution, and its link to mechanical, thermal, and transport properties. In this conference paper we report the use of a powerful, yet not so wide-spread, set of X-ray techniques based on refraction effects. X-ray refraction allows determining internal specific surface (surface per unit volume) in a non-destructive fashion, position and orientation sensitive, and with a nanometric detectability. We demonstrate showcases of ceramics and composite materials, where microstructural parameters could be achieved in a way unrivalled even by high-resolution techniques such as electron microscopy or computed tomography. We present in situ analysis of the damage evolution in an Al/Al2O3 metal matrix composite during tensile load and the identification of void formation (different kinds of defects, particularly unsintered powder hidden in pores, and small inhomogeneity’s like cracks) in Ti64 parts produced by selective laser melting using synchrotron X-ray refraction radiography and tomography.
Strength and Axial Behavior of Cellular Lightweight Concrete-Filled Steel Rectangular Tube Columns under Axial Compression
Authors: Thumrongvut Jaksada , Tiwjantuk Pavarate
Published: December 2018

This paper presents the experimental results on the strength and axial behavior of rectangular steel tube columns filled with cellular lightweight concrete (CLC) under axial compression. A total of 24 specimens, including 6 reinforced cellular lightweight concrete (RCLC) columns and 18 cellular lightweight concrete-filled steel tube (CLCFT) columns are investigated. The nominal dimension of the rectangular columns are 150×75 mm in cross-section and 750 mm in height. The parameter used in all tests are the ultimate compressive strengths of the CLC, which are 15 MPa, 20 MPa and 25 MPa, and the wall thicknesses of steel tubes, which are 3.0 mm, 4.5 mm and 6.0 mm. All specimens are prepared and loaded concentrically in axial compression to failure. The results of these tests demonstrated that the CLCFT columns have a linear behavior up to the approximately 80-90% of their maximum compressive load. Then, the behavior of the columns is nonlinear. The nonlinear behaviors are due to the crushing of the concrete core and local wall buckling of the steel hollow tube. In addition, it is found that the CLCFT columns have high axial deformability at the failure when compared to the reference RCLC columns. Finally, by comparing the maximum compressive load of the test results with those obtained from the ACI composite design equation, the comparison results show that calculation formula in ACI code can be applied to compute the axial capacity of CLCFT columns under axial compression.
Implementation and Use of a Laser-Ultrasonic System in a Deformation- and Quenching Dilatometer
Authors: Scherleitner Edgar , Reitinger Bernhard , Gruber Markus , Burgholzer Peter
Published: December 2018

State of the art of in-situ analysis on grain structure of metals during thermal and stress treatment is done by observation of the probe in a thermomechanical treatment system. Potential analysis methods are high energy x-ray scattering (e.g. in a synchrotron) or laser-ultrasonics (LUS). The most commonly used thermomechanical system, is the so called “Gleeble” from Dynamic Systems Inc., which is able to heat and load the material in a quite fast manner with extremely high heating rates, very high forces and fast force changes. There is a wide area of research and applications, though, where these capabilities are not fully required, a less complex deformation-and quenching dilatometer would often be sufficient. In this paper we will show the implementation of a LUS system in such a dilatometer and compare it to the “all inclusive” Gleeble system, pointing out benefits and downsides on different aspects, like the technical specifications, the needed footprint and more. A sketch of the full system and the beam path will show the general idea on the implementation of the LUS system into the dilatometer. We will also present first results of a thermal treatment on a metal sample suited for grain structure and phase transition analysis.
Quality Assessment of Friction Stir Welded Joints – Using the Fundamental Anti-Symmetric Lamb Wave Mode
Authors: Hamade Ramsey , Fakih Mohammad Ali , Harb Mohammad , Mustapha Samir
Published: December 2018

Having a robust non-destructive evaluation (NDE) technique for friction stir welded (FSWed) joints is of interest to the processing community. Such a technique has to be sensitive to the different types and shapes of internal weld defects and has to be applicable for both similar and dissimilar material FSW joints. Investigated was the ability of ultrasonic guided waves to detect and assess the quality of FSW joints. The fundamental anti-symmetric (A0) mode was selected to detect the flaws in FSW joints. Guided waves were excited (using PZT wafers) and received (using a laser Doppler vibrometer, LDV). Implemented was the frequency-wavenumber filtering technique to separate forward propagating wave from any back propagating reflected wave due to the welded joint. Identified was the reflection of the A0 mode caused by the presence of the interface and/or defects within the joint. The findings indicate little sensitivity to the presence of material interface suggesting this technique to have a promising potential among guided-wave-based techniques in the qualitative and quantitative assessment of FSW joints.
Validation of Material Parameters of Collagen Compositions for the Application as a Bioink
Authors: Schlegel Volker , Engels Andreas , Bifaretti Stefano , Foitzik Andreas H.
Published: December 2018

The novel approach of an individualized medicine affects nowadays various areas of therapeutic treatment. Primarily, these include the application of pharmaceuticals, private point-of-care solutions, surgical procedures as well as steps of rehabilitation. However, beside these existing strategies the development of patient specific models for the training of clinical personal is currently insufficient. Such models are essential to prepare a personalized approach of medical care. One possible solution to address this problem could be the adaption of the established 3d printing technology for the processing of suitable biopolymers. The presented work is focused on the development of a printing system utilizing collagen. Therefore, it is intended to design multiple extrusion heads in accordance with the material parameters. In order to achieve the aspired physiological properties of the final model, a first set of experiments will be performed with several compositions of collagen to validate the fundamental mechanical characteristics. Hereby, the elasticity, thermal stability, force resistance as well as the haptic behaviour are of most interest. Afterwards, these obtained experimental results should be used to simulate the extrusion process and to validate the extruder concepts. In case of a positive evaluation these concepts are realized by using rapid prototyping technologies. Finally, this novel 3d printer will be used to print first organic test structures with collagen.
Improved Syringe Extruder for Improved Processing of Biological Materials
Authors: Engels Andreas , Schlegel Volker , Zinn Steffen , Bonaiuto Vincenzo , Foitzik Andreas H.
Published: December 2018

3 dimensional (3D) printing evolved during the last decade to a consumer friendly and affordable craft. Furthermore, implementations of this techniques in the field of biotechnological research and development within laboratories is a very expansive process. Bio-printers’ prices cover a wide spectrum and most basic models are available for around 5000€. On the other end, high-end printer machines with a vast variety of features are available for several hundreds of thousands of euros. Thus, due to the immense potential in the field of Biotechnology the availability of this technology for research purpose should be enhanced. A developed ecological syringe extruder prototype for processing of biological based gels has been further improved. The original prototype was capable to processing multiple layers of agar with concentrations of 1% and 2.5%. Based on these results the prototype was revised regarding printing process parameter, which include among others applied forces to the substrate, air-ventilation, and heating of the substrate. The process behavior will be simulated with computational fluid dynamics for the processing of biological based substrate. After a concluding validation these results are intended to be implemented into a new design for improved processing of a variety of bioinks.
Manufacturing of Biomedical Ti-Based Alloys with High Oxygen Content and Various Amount of Beta-Stabilizing Elements
Authors: Stráský Josef , Preisler Dalibor , Bartha Kristína , Janeček Miloš
Published: December 2018

High strength and low elastic modulus are key properties of biomedical Ti-based alloys. Body centred cubic beta phase shows lowest elastic modulus, especially if the stability of the beta phase is low due to the ‘proximity’ to martensitic β to α’’ transformation. It was previously shown that Ti-35Nb-6Ta-7Zr alloy contains biotolerant elements only and exhibits low modulus. By enriching this alloy by 0.7 wt. % of oxygen the strength is significantly enhanced, but elastic modulus increases as well. This fact can be attributed to apparent beta stabilizing effect of oxygen with respect to martensitic β to α’’ transformation. In the present study, six different alloys with reduced niobium and/or tantalum content were prepared by vacuum arc melting. Their microstructure in beta solution treated condition was studied by scanning electron microscopy including energy dispersive spectroscopy and mechanical properties were evaluated by microhardness measurements.
Biofunctionalization of Ceramic Implant Surfaces to Improve their Bone Ingrowth Behavior
Authors: Schnabelrauch Matthias , Dubs Manuela , Kautz Armin R. , Weisser Juergen , Bergemann Claudia , Rebl Henrike , Schmidt Jürgen , Witt Carolin , Oberbach Thomas , Imhof Diana , Nebe J. Barbara
Published: December 2018

Surface biofunctionalization is a common strategy to improve the material-tissue interface of inert implant surfaces. In this context we coated alumina-toughened zirconia (ATZ) ceramics after titanium plasma spraying with two different porous calcium phosphate layers and subsequently functionalized the obtained surfaces either with an RGD containing cell adhesion peptide sequence or a bone morphogenetic protein (BMP)-glycosaminoglycan complex. We studied initial cell adhesion densities, integrin expression, and alkaline phosphatase activity as an osteogenic marker of the coatings in vitro in comparison to the non-functionalized ATZ ceramics to evaluate the bone ingrowth potential of these biofunctionalized implant coatings.
Online Glucose Measurement in DMEM for In Vitro Cell Culture
Authors: Matuschek Nelson , Liebscher Thilo , Santo Loredana , Foitzik Andreas H.
Published: December 2018

In-vitro cell culture offers the ability to grow individual cells and monitor their behaviour in a controlled environment over a certain time. During culture, different parameters have to be controlled to ensure a vital growth of cells. The most important parameters are temperature, pH-value, oxygen and carbon dioxide levels as well as the glucose concentration. All of these parameters influence the growth ability of the cell culture and should be monitored online. The online monitoring of glucose was achieved with a novel GOD based sensor which enabled a real-time measurement of glucose during cell culture. A first-time characterisation of the sensor was carried out in the culture medium DMEM. In addition, material properties of the culture system were investigated. At first to establish a baseline measurement, the sensor was placed in different glucose concentrations dissolved in Water-KCl mixture at 25 °C inside a batch chamber under constant stirring. Afterwards, the temperature was increased to 37 °C to simulate a cell culture environment. In addition, the system was transferred into a flow-through reaction chamber. The highest response signal and the most stable signal was achieved at 37 °C with DMEM during flow-through measurement. Based on these measurements online glucose monitoring in cell culture was possible to determine the glucose consumption for each cell which is important for future human-on-a-chip devices to prevent diabetic metabolisms.
Control of Cell Adhesion on Titanium Dioxide by Light Irradiation
Authors: Ueda Masato , Yamaguchi Rika , Fujita Chika , Ikeda Masahiko
Published: December 2018

Several techniques have been employed to attach/detach cells to/from a substrate. Cells cultured on a substrate are generally detached from the substrate into a sheet by the destruction of protein between the cells and the substrate using enzymes such as trypsin. However, the enzymes also damage the adhesion molecules among the cells. TiO2 is an n-type semiconductor with an energy band gap of 3.0-3.2 eV, which displays a photocatalytic activity under ultraviolet (UV) light. The purpose of this work was to fabricate photo-responsive cell culture vessel using TiO2 film and to investigate adhesion behaviour of cells on it. TiO2 films were prepared on SiO2 plates by a sol-gel method using titanium tetraisopropoxide. Primary osteoblasts were seeded on the vessels and then incubated at 37 °C. During the incubation, UV irradiation was performed continuously from back-side of the vessels. Basically the number of cells monotonically increased with incubation periods under darkness. Previous light irradiation promoted the cell adhesion on the surface. The formation of Ti-OH groups on the TiO2 seems to be facilitated by the UV irradiation. In contrast, the cells decreased under continuous light irradiation. The cells were not exposed to UV in the vessels since it was completely absorbed by the TiO2 layer. It might be due to generated photocurrent or hydroxyl radicals on the TiO2 surface. These results imply that the adhesion/proliferation/detachment behaviours of cells can be controlled by the photocatalytic reaction of TiO2 and the irradiation patterns.
Ferrite-Martensite Dual-Phase Steel Produced by a Modified Quenching and Partitioning Process
Authors: Di Hong Shuang , Deng Yong Gang , Li Jian Ping
Published: December 2018

One industrially C-Mn steel was studied in the present work. The Mn pre-partitioning process during continuous annealing was used. The results showed that the stability of retained austenite is increased because of the Mn pre-partitioning. The amount of retained austenite was about 5%, when increase the partition time to 100s. With the increase of the partition time, the amount of retained austenite increases, the tensile strength decreases, the yield strength and elongation both increase. Compared with quenching and tempering (Q&T) process, the tested steel after pre-partitioning quenching and partitioning (PQ&P) process has higher uniform elongation and the product of strength and elongation (UTS×TEL).
Monitoring of Cytotoxic Induced Cellular Displacements by Utilizing Electronic Speckle Pattern Interferometry
Authors: Gottschalk Josefine , Krumnow Erik , Lietzau Kai Henning , Foitzik Andreas H. , Richetta Maria
Published: December 2018

Modern medical science delivers through innovative chemical or mechanical/physical means new strategies to treat patients mildly and fight diseases accurately. In line with this development a screening procedure for tissue samples under usage of the electronic speckle pattern interferometry is developed at the University of Applied Science Wildau. The paper at hand provides the corner stone for such a procedure in form of an incubation system that is adapted to the properties of an electronic speckle pattern interferometer and allows the incubation as well as study of samples over time. As a result the developed system can regulate its own temperature and is constructed for use in an electronic speckle pattern interferometry (ESPI) setup. Its design allows a simple modular approach for further development
Sample Analysis for Novel Medical Applications
Authors: Lobstein Susanne , Zinn Steffen , Minieri Marilena , Foitzik Andreas H.
Published: December 2018

The sample preparation for biological and chemical probes involves following a strict workflow to eliminate any contamination to the sample beforehand. Furthermore, it is time consuming and must be carried out by trained personnel such as a nurse or other supervisors, making it therefore expensive. The development of novel sample preparation techniques paired with modern sample analysis systems is focused on improving the operability while keeping a constant quality of results. This is important to analyse samples, which cannot be determined with current screening conditions. The analysis of analytes is required to receive a more detailed picture of the patient and to fully understand its complexity. Possible samples for in-depth analysis of chemical origin can be cholesterol or glucose. More complex samples, such as blood or saliva, require a sophisticated system, which analyses the samples for their individual compounds.
Development of a Smartphone Based Reader for the Quantitative Analysis of Lateral Flow Assays
Authors: Schneider Sylvio , Selig Martina , Keil Verena , Lehmann Matthias , Foitzik Andreas H. , Casalboni Mauro , Richetta Maria
Published: December 2018

Smartphones are developing into all-purposes devices. In the present work, the employment/application of smartphones as medical devices in home care and point-of-care (POC) diagnostics are investigated in the analysis of Lateral Flow Assays (LFA). A smartphone-based LFA reader was developed for the quantitative analysis of D-Dimer – a biomarker indicating e.g. thrombotic event or danger of embolism.The proof-of-concept has been shown with multiple smartphones in establishing: (I) Optimal dimensions of the LFA cell of 72.11mm distance of smartphone to D-Dimer test leading to a coefficients of variances (CV) between 0.8% and 4.2%. (II) Inter-device investigations: CVs around 13.5%; a limit of detection (LOD) of 100ng/ml (DDU) D-Dimer. (III) Inter-smartphone investigations: CV about 16%, a limit of detection (LOD) at 66.4ng/ml (DDU). (IV) Calibrations: CV and LOD of three smartphones are comparable to the commercial available LFA reader. Further development to put the multiple smartphone-based LFA reader on the market.