bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress Gradient Determination in Anti-Corrosion Multilayer Coating
Authors: Dubos Pierre Antoine , Hatte Quentin , Casari Pascal , Richard-Plouet Mireille , Jouan Pierre-Yves , Branchu Samuel , Guitter Nadia
Published: December 2018

To reduce maintenance and to increase the corrosion protection and lifetime of maritimestructures while complying with environmental standards, multilayer coatings are applied to protectsteel sections. A new generation of hybrid sol-gel and/or HiPIMS Ni-based thin films appear toconstitute an efficient pre-treatment before the anti-corrosion paint application. However, increasingthe number of coatings and associated interfaces may lead to coating failure due to stresses inducedby the different deposition processes. Therefore developing smart models to assess the stressdistribution along these multilayers appears of significant importance. The well-known Stoneyformula cannot be used for multilayers and owing to the large dimensions of the object to be protected.To assess an easily measurable curvature after deposition, thin steel sheets are used but do not respectany more the Stoney hypotheses. So we set up an analytical thermo-elasto-plastic model to evaluatethe stresses induced by depositions in each layer. This model is based on the various thermalexpansion coefficients of every coat. After extrapolation along the complete thickness, combiningsol-gel and PVD deposition smoothens the stress difference between steel and paint. The shearstresses at interface seems thus to be reduced. The evolution of the stress difference between layerswith the imposed deflection can predict the mechanical strength and the interface failure. In order toevaluate the quality of the model, in-situ four-point bending in SEM was performed to study of theadhesion between the various layers. The results deduced from the model are in good agreement withSEM images.
Investigation of the Splat Deposition Behavior onto a Composite Coating in Cold Spray
Authors: Chu Xin , Vo Phuong , Yue Stephen
Published: December 2018

The splat test is usually generated by low feed rate cold spraying of particles onto an as-polished substrate and it can be considered as a monolayer coating deposition. In this study, in order to investigate cold spray deposition mechanisms, Fe splats were sprayed onto the cold-sprayed single component 316L, Fe, and a composite 90Fe coatings. Results showed that although there is only 3.6 vol.% of 316L in the composite 90Fe coating, Fe splats exhibit a much better deposition behavior onto the 90Fe as compared with the single component Fe coating. To explain this observation, Fe splat samples were characterized using the scanning electron microscope (SEM), optical profilometry, splat adhesion tests, and splat nanoindentation. Finally, a preliminary explanation towards the Fe splat deposition behavior onto the composite coating was drawn.
Effect of Coiling Temperature on the Hardening Mechanisms of a High-Ti Steel
Authors: Pereda Beatriz , Garcia-Sesma Leire , López Beatriz
Published: December 2018

In recent years, steels microalloyed with high Ti levels have received increasing attention due to the interesting combination of high strength and formability because of the dispersion of nanometric sized titanium carbides that can be formed within the matrix. However, one of the problems related to these compositions is that their performance can be highly sensitive to variations in the processing route. To study this, in this work coiling simulations were performed by dilatometry tests with a reference Nb microalloyed steel (0.03%Nb) and a high-Ti steel (0.03%Nb-0.1%Ti) using temperatures from 550 to 675oC. The mechanical behaviour of the samples was characterized using Vickers hardness. A large hardness increase was observed in the high-Ti steel samples, resulting in estimated yield strength increases between 69 and 214 MPa. This improvement in the mechanical behaviour was very dependent on the coiling temperature; the maximum hardness was observed at 625oC-650oC, while this decreased drastically for temperatures from 550oC to 600oC and at 675oC. EBSD and TEM analysis has been performed to study the contribution of microstructural constituents and precipitation to the observed mechanical behaviour.
Superhydrophobic and Corrosion Protective Coating on Aluminium
Authors: Escobar Romero Ana Maria , Rius-Ayra Oriol , Llorca-Isern Nuria , Valles Gimenez Elisa , Serrà i Ramos Albert
Published: December 2018

Industrial application of superhydrophobic surfaces is limited by the unsatisfactory mechanical properties of the material. Combining chemical etching and anodization terraced features containing aluminium oxide on different aluminium alloy surfaces were produced. After modified by fatty acid, the surfaces were superhydrophobic and they showed self-cleaning effect. The highest contact angle was obtained after forming hierarchical structures with a solution free of fluorine compounds; therefore, the process is considered eco-friendly. The alumina formed in the coating process promotes an improved corrosion resistance. The present study has three main objectives: to identify the molecules responsible for superhydrophobicity, the mechanism by which superhydrophobicity is produced, and consequently the influence of variables such as anodization time on the proposed processing method. We use time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) techniques to identify each compound involved in the final surface, by paying close attention to the analysis of the mechanism by which the chemical reaction proceeds. The morphology of the superhydrophobic surfaces was further observed by scanning electron microscope (SEM) and atomic force microscopy and was used to elucidate the effect of the anodization time in the properties of the superhydrophobic material.
Response of Cold Sprayed Ti6Al4V Coatings to Solid Particle Erosion and Micro-Scratch Wear Processes
Authors: Garrido-Maneiro Miguel Ángel , Sirvent Paloma , Elvira Daniel , Rico Álvaro , Munez Claudio , Poza Pedro
Published: December 2018

Ti6Al4V alloy is widely used for aeronautical components due to a special combination of high mechanical properties, low density and good corrosion resistance at high temperature. These components are usually damaged by particles impacts during their operating time. When the reliability of these components is compromised, they are replaced with the consequent cost of material and time. Spraying coatings on the damaged surface could reveal as an alternative process to repair these components, increasing their operating life. Traditionally, thermal spray processes are used to repair the aeronautical components. However, the coatings produced by these processes are characterized by high residual stresses, porosity and oxidation. The cold spray technique is revealed as a promising spraying alternative due to the characteristic low temperature of the process. Consequently, residual stresses, oxidation, crack formation, phase transformations and microstructural changes are minimized. In this work, a cold spray technique was used to generate Ti6Al4V coatings onto a bulk of the same material. Three different spraying conditions were studied: Ti6Al4V coatings sprayed at 800oC; Ti6Al4V coatings sprayed at 1100oC; and Ti6Al4V coatings sprayed at 1100oC with a subsequent heat treatment: The wear resistance of these coatings was investigated by solid particle erosion and micro-scratch tests. The wear behaviour was determined under several wear tests conditions. Additionally, instrumented indentation tests were carried out on the coatings to determine their mechanical response. The wear mechanisms of the coatings were identified and compared to their microstructure and mechanical properties.
Oscillating Contact Wear in Cold Sprayed Ti6Al4V Coatings for Aeronautical Repairs
Authors: Poza Pedro , Sirvent Paloma , Rico Álvaro , Munez Claudio , Garrido-Maneiro Miguel Ángel
Published: December 2018

Ti6Al4V coatings were cold sprayed onto the same bulk alloy using standard conditions and a set of parameters developed to improve the coating’s performance. In addition, the enhanced coating was heat treated to improve coating adhesion and reduce porosity. Wear tests were performed, onto the coatings and the substrate, in oscillating conditions, which simulate wear induced by the contact with bearing parts during vibration. Wear behaviour at room temperature is dominated by a mixed mechanism, which involves plastic deformation and transference from the counterbody forming mechanically mixed layers. As temperature is increased, the formation of mechanically mixed layers dominates wear. The wear resistance of the enhanced coatings is similar to the bulk alloy, or even better in some conditions. Consequently, cold sprayed improved coatings could be used for repairing titanium components from the contact wear point of view.
An Experimental Method to Evaluate the Effect of Welding Residual Stress on Corrosion Fatigue Properties of Structural Steel in Synthetic Seawater
Authors: Ishibashi Yuko , Kayamori Yoichi
Published: December 2018

Tensile residual stress can cause a reduction in the fatigue strength of steel not only in air but also in corrosive environments. In air, for example, the effect of residual stress on fatigue strength can be estimated by using relations between fatigue strength and mean stress such as the modified Goodman diagram. However, it is not clear whether a sort of fatigue strength estimation can be applicable to corrosion fatigue properties. This paper presents an experimental method to evaluate the effect of welding residual stress on corrosion fatigue properties quantitatively, where corrosion fatigue tests were conducted in synthetic seawater by using characteristic fatigue specimens that have two parts, a tensile residual stress part and the other supporting part. Bead-on-plate welding was performed for applying welding residual stress in the tensile residual stress part. Residual stress relaxation was measured using the X-ray diffraction method in the midst of fatigue testing. Effects of tensile residual stress on corrosion pit growth and S-N curves were discussed.
Change of Intergranular Corrosion Behavior along the Thickness in a Friction-Stir-Welded 7N01-T5 Aluminum Alloy
Authors: Zhang Zhi Qiang , Li Ying , Xing Yan Shuang , Yin Hua , He Chang Shu
Published: December 2018

The intergranular corrosion behavior of friction-stir-welded 7N01-T5 aluminum alloy joints was investigated by using sliced samples extract from the top, middle and bottom layers of the joint, with the sliced direction parallel to the welding direction. The relationship between microstructure and local corrosion property of the welded joints was analyzed. The results show that the heat-affected zone (HAZ) of the weld exhibit the highest susceptibility to intergranular corrosion, and the corrosion degree of the top and bottom surface layers were more serious than the central layer in the HAZ, continuously dispersed precipitates on grain boundaries and the grains size may be the main factor which caused the different corrosion severity of HAZ. The thermo-mechanically affected zone (TMAZ) is characterized by a highly deformed structure, and the temperature reached in this local zone during welding is high enough for the strengthening precipitates, especially the precipitates on the grain boundary to be partially re-dissolved. The temperature gradient caused resistance to intergranular corrosion of TMAZ reduced from top to bottom surface. The stirred zone (SZ) experienced heavily plastic deformation and temperature cycling, the sensibility of intergranular corrosion was low, which is attributed to the sufficient re-dissolve of the strengthening precipitates during welding.
Effect of Sn, Zn and Bi Addition on Corrosion Characteristics of Magnesium Alloys Sintered by Spark Plasma Sintering
Authors: Sunada Satoshi , Matsui Yoshitaka , Takeuchi Syogo , Iwaoka Taku , Sato Koichi , Hatakeyama Masahiko
Published: December 2018

Sintered magnesium alloys, which were fabricated by Spark Plasma Sintering (SPS) method, were examined to study corrosion characteristics by electrochemical method, XRD and EPMA. The binary mixtures alloys of a low-melting-point metal powder (Sn, Bi, Sb) of1.0 vol.% and the pure magnesium powder were prepared. In the Mg-1.0vol.%Bi and Mg-1.0vol.%Sn, Mg3Bi2 and Mg2Sn precipitates was recognized by XRD, respectively. In addition, formation of oxide along powder particle boundaries was observed by EPMA elemental mapping in all specimens. In the case of Mg-1.0vol.%Zn, precipitation of metallic compounds was not recognized by these experiments. According to the results of polarization curve measurements, the Mg-1.0vol.%Bi shows highest corrosion potential. However, corrosion rate which was estimated by Tafel method is relatively larger than other alloys due to Mg3Bi2 precipitation. This result suggests that Mg3Bi2 acts as cathode site. The Mg-1.0vol.%Sn shows superior corrosion rale in these alloys.
Effects of Post-Drawing Surface Heat Treatments on the Strength and Torsional Ductility of High Strength Steel Wire
Authors: Ciganik Christina , Speer John , Findley Kip O. , van Raemdonck Walther
Published: December 2018

Along with high tensile strength, high carbon steel wires must possess sufficient torsional ductility is to avoid longitudinal splitting along the wire axis, known as delamination. Often, wires ductile in the bright (asdrawn) surface condition exhibit delamination failure after undergoing a post-drawing surface treatment such as hot-dip galvanizing. The objectives of this study were to examine the influence of postdrawing heat treatment time and temperature on drawn wire mechanical properties, and to identify possible treatment conditions that suppress delamination. Stelmor cooling or lead patenting prior to drawing were used to develop a pearlitic microstructure. Salt pot heat treatments simulated postdrawing heat treatments; experimental heat treatments were conducted between 325 °C and 475 °C for 20 s or at 450 °C for immersion times between 1 s and 20 s. Tension and torsion tests quantified the changes in mechanical properties due to aging. Lead patented wires experienced greater tensile strength and torsional ductility changes with aging time and temperature when compared to the Stelmor cooled wires. This increased sensitivity was attributed to greater dislocation recovery in the patented wire after drawing.
First-Principles Study of Chlorine Adsorption on Clean Aluminum Surface
Authors: Yamashita Jun , Nunomura Norio
Published: December 2018

Using density functional theory (DFT) we investigated the adsorption of chlorine atom on aluminum surface in the orientations, (100), (110), and (111). The structural and thermodynamic properties of chlorine atoms adsorbed on the Al (100), Al (110), and Al (111) surface for chlorine coverages of 1/9, 1/4, 1/3, 1/2, 3/4, and 1 monolayer (ML) are calculated. The largest bond strength is observed for a top, fcc, and hcp mixed structure at 3/4 ML coverage on Al (111). Adsorption free energy analysis reveals that the chlorine coverage of 3/4 ML of Al (111) is the most thermodynamically stable over the widest range of chlorine chemical potential and 1 ML of Al (111) is thermodynamically unstable, whereas various chlorine coverages of Al (100) and Al (110) take stable phase for a range of chlorine chemical potential.
Development of the Projection Welding Technology for High-Strength Steel Sheets
Authors: Furusako Seiji , Kodama Shinji , Yasuyama Masanori , Miyazaki Yasunobu
Published: December 2018

High-strength steel sheets (HSSs) have been increasingly used to reduce the weight of automobile bodies. It is necessary to enhance the reliability of their joint strength in order to realize optimal usage. Projection welding (PW) is one of the important welding methods for HSSs; however, research on PW is insufficient. In this research, therefore, the effect of welding conditions on maximum load in the press-peel test for joints, made by PW HSS of 590 MPa grade and square weld nuts, was investigated. It is found that the maximum load showed a tendency to increase with an increase in the current and a decrease in the electrode force. In several cases of the press-peel test, four welds of one joint fractured one by one in sequence and showed a peak load each time it broke. The first or second peak load became the maximum load of each joint. SEM (Scanning Electron Microscope) observation of the welds fractured at the early stage in the press-peel test revealed that the fractured surface can be classified into a good weld region and a bad one. The former was a dimple fracture surface or cleavage one and the latter was a relatively flat fracture surface with many oxides. The same analysis was conducted for joints with several welding conditions. It was consequently found that there is a good correlation between the area of good weld region and the maximum load. In addition, it was considered that the scattering of moderate expulsion during PW was effective for reducing oxides.
Mechanical Property of Magnesium Alloy Surface with Dense Oxide
Authors: Watazu Akira , Sonoda Tsutomu
Published: December 2018

Low Al single-phase magnesium alloy surfaces with dense magnesium oxide films were uniformly formed. The films were deposited with a radio frequency magnetron sputtering process with a planar magnetron sputtering system. The thickness of deposited magnesium oxide thin films was around 240 nm. According to the XRD results, a magnesium oxide phase film was formed on the substrate. The surface was uniform, and no cracks or exfoliation were observed. The deposited magnesium oxide film did not have any cracks or pores, and the surface of the sample was covered by magnesium oxide. The hardness of the magnesium oxide-coated magnesium alloy reached around Hv200, while that of the uncoated Mg-alloy was around Hv80. Moreover, the Vickers indenter under a 10-mN load indented the magnesium alloy substrate coated with the magnesium oxide film to a depth of around 640 nm, while that for the uncoated magnesium alloy substrate was around 620 nm. Meanwhile, the elasticity value for the magnesium alloy substrate coated with magnesium oxide film was around 5.3×1010 Pa, while that of the uncoated magnesium alloy substrate was around 4.2×1010 Pa.
Corrosion Mechanisms of New Wrought Mg-Al Based Alloys Alloying with Mn, Zn and Sn
Authors: Ben Hamu Guy , Metalnikov Polina , Eliezer Dan , Shin Kwang Seon
Published: December 2018

The low density and high strength/weight ratio of magnesium (Mg) and magnesium alloys make them promising candidate materials in light-weight vehicle industries, such as automobile and aerospace, where poor corrosion resistance is a major obstacle in many of their wide-spread applications. Addition of alloying elements with production of wrought Mg alloys with finer microstructure results in enhanced mechanical properties and corrosion resistance. The aim of this research is to study the changes in microstructure caused by addition of alloying elements (zinc (Zn), and tin (Sn)) to new wrought Mg-5Al alloy, and their influence on the alloy's corrosion behavior. The microstructure was investigated using optical and electron microscopy and EDS. The corrosion behavior was analyzed through electrochemical measurements and immersion test. It was found that the corrosion resistance of Mg-5Al alloy was improved by addition of alloying elements, and the amounts of these elements strongly influenced the corrosion behavior of the alloys. Nevertheless, the influence of alloying elements is different for short-term and long-term immersion periods, since the mechanisms of corrosion initiation and corrosion propagation are different.
Cold Spray of Mixed Sn-Zn and Sn-Al Powders on Carbon Fiber Reinforced Polymers
Authors: Che Han Qing , Liberati André , Vo Phuong , Yue Stephen
Published: December 2018

Carbon fiber reinforced polymers (CFRPs) have been increasingly used in the latest generations of aircraft and helicopters for lightweight purposes, but this leaves vulnerability against lightning strike. Cold spray is one coating approach to metallize the polymers, thus making them lightning strike proof. It has been reported that direct cold spray of metals onto CFRP is difficult. However, research at McGill University has shown that tin coatings can be cold sprayed on CFRP, but the deposition efficiency is very low. In this work, aluminum and zinc powders were mixed with tin to investigate the effect of mixing on deposition efficiency of the coating. The mixed metal powders were cold sprayed on CFRP with a low-pressure cold spray system at various conditions. It was found that the addition of aluminum or zinc resulted led to increased deposition efficiencies compared to pure tin, but there are many differences in the details of the effect of Al and Zn additions on the deposition characteristics. The deposition mechanism of the mixed metal powders on CFRP is discussed, and the effect of mixing powders on the deposition efficiency is evaluated.
Deformation Properties of Austenitic Stainless Steels with Different Stacking Fault Energies
Authors: Molnár Dávid , Engberg Göran , Li Wei , Vitos Levente
Published: December 2018

In FCC metals a single parameter – stacking fault energy (SFE) – can help to predict the expectable way of deformation such as martensitic deformation, deformation twinning or pure dislocation glide. At low SFE one can expect the perfect dislocations to dissociate into partial dislocations, but at high SFE this separation is more restricted. The role of the magnitude of the stacking fault energy on the deformation microstructures and tensile behaviour of different austenitic steels have been investigated using uniaxial tensile testing and electron backscatter diffraction (EBSD). The SFE was determined by using quantum mechanical first-principles approach. By using plasticity models we make an attempt to explain and interpret the different strain hardening behaviour of stainless steels with different stacking fault energies.
Competitive Reactions and Formation Mechanism of Microstructures in Mg/Cu Super-Laminate Composites during Initial Hydrogenation
Authors: Tanaka Koji , Kondo Ryota , Takeshita Hiroyuki T.
Published: December 2018

Competitive reactions and formation mechanism of microstructures in Mg/Cu super-laminate composites (SLCs) during initial hydrogenation were studied. During initial hydrogenation of Mg/Cu SLCs, hydrogenation of Mg and alloying of Mg with Cu followed by hydrogenation of Mg2Cu are competitive. It is found that microstructures of Mg/Cu SLCs during initial hydrogenation have changed drastically depending on the order of hydrogenation of Mg and Mg2Cu. The microstructures of Mg/Cu SLCs after initial hydrogenation can be categorized in 3 types.
Evaluation of Effective Thermal Conductivity of Metal Matrix Composites by Using Image-Based Calculation
Authors: Sugio Kenjiro , Kono Keisuke , Choi Yong Bum , Sasaki Gen
Published: December 2018

Interfacial thermal resistance in Al-SiC composites was evaluated by comparing the measured thermal conductivity and the calculated thermal conductivity. Al-20vol.%SiC composites changing SiC particle size, 3 μm to 30 μm, was fabricated by spark plasma sintering and heat treatment. Effective thermal conductivity was measured with the steady state thermal conductivity measuring device. Effective thermal conductivity was also calculated by using SEM image and the measured relative density. Comparing the measured thermal conductivity and the calculated thermal conductivity, interfacial thermal resistance in Al-SiC composites was evaluated as about 1.0x10-8 (m2K)/W.
Effect of Slit Shape on Joinability of Zircaloy - SiC/SiC Composite Tube Joint with Titanium Powder
Authors: Serizawa Hisashi , Sato Yuji , Nakazato Naofumi , Tsukamoto Masahiro , Kishimoto Hirotatsu
Published: December 2018

As for the fuel cladding in the light-water reactor, silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composite is one of the promising candidates as a replacement of Zircaloy due to many superiorities, where it is necessary to develop the end-cap seal of SiC/SiC composite cladding. In this research, the caulking method was employed as the method for sealing the end cap of SiC/SiC composite tube by Zircaloy tube where the titanium micro-powder was inserted between two tubes. The fiber laser was circumferentially irradiated on the outer surface of zircaloy tube, and the insert method of titanium powder was varied by changing the cutting method of SiC/SiC composite tube. The examinations about the slit shape effect for the flat cutting suggested that the hook slit is considered to be the best cutting method for holding the titanium powder during the laser irradiation where the width of slit should be narrower than that of laser irradiation line.
Metallic Composites as Form-Stable Phase Change Alloys
Authors: Gariboldi Elisabetta , Perrin Maxime
Published: December 2018

Metallic materials can be used as Phase Change Materials for thermal storage, since they absorb/release relatively high latent heat for solid/liquid transformation during the heating/cooling parts of thermal cycles including their melting/solidifying range. The active PCM phase can also be mixed to another phase, melting at higher temperature, forming metallic composites, also referred in literature as Phase Change Alloys. To be considered as ‘form stable’ material, leakage of the molten active phase must be prevented. The present contribution focuses on the processing/microstructure/ properties correlations of PCAs based on the simple Al-Sn system, with activation temperature of about 230°C. They were produced by mixing Al powders to two different Sn powders adopting different compaction techniques and heat treatments, and cycled to simulate service. Their microstructure, thermal and mechanical response in as-manufactured and after service revealed that, amongst those experimentally available, PCA produced by compaction at room temperature inhomogeneous a blend of the powders is the optimal procedure, with good absorbed/released enthalpy and thermal stability after service.
Characteristics and Formation Mechanism of the Interface of Mg/Al Bimetallic Composites Prepared by Lost Foam Casting
Authors: Jiang Wen Ming , Fan Zi Tian , Li Guang Yu
Published: December 2018

In the present work, the Mg/Al bimetallic composites were successfully prepared by the lost foam casting (LFC) process, and the characteristics and formation mechanism of the interface of the Mg/Al bimetallic composites were investigated. The results show that a uniform and compact metallurgical interface with an average thickness of about 1400 μm was formed between magnesium alloy and aluminum alloy. The interface layer of the Mg/Al bimetallic composites was composed of three different reaction layers, namely the Al12Mg17+δ(Mg) eutectic layer adjacent to the magnesium matrix, the Al12Mg17+Mg2Si interlayer and the Al3Mg2+Mg2Si layer close to the aluminum matrix. The microhardnesses of the interface layer were remarkably higher than those of the magnesium and aluminum matrixes. The stress strength of the Mg/Al bimetallic composites was up to 47.67 MPa. The fractograph of the push out sample mainly showed a brittle fracture nature. The formation of the interface of the Mg/Al bimetallic composites was attributed to the fusion and diffusion bonding. With the variations of the concentrations of the different elements at the interface, the Al3Mg2 intermetallic phase first formed near to the aluminum matrix, and then the Al12Mg17 and Mg2Si successively generated toward the magnesium matrix, finally obtaining the interface layer of the Mg/Al bimetallic composites.
Particle Distribution and Mechanical Properties of Nano-SiCP/Al-Cu Composites
Authors: Wu Shu Sen , Li Jian Yu , An Ping , Lü Shu Lin
Published: December 2018

Generally it is difficult to disperse nanosized particles uniformly in metal matrix. In this paper nanoSiC particles reinforced Al-5%Cu matrix composites were prepared by molten-metal process, combined with high energy ball-milling and ultrasonic vibration methods. Ultrasonic vibration treatment (UV) has been successfully used to disperse the particles distribution of nanoSiCp particles in the matrix. Big aggregates of particles are eliminated by the effects of cavitation and the acoustic streaming of UV for 1 min. All the particles aggregates are eliminated and the particles are uniformly distributed in the melt after treated by UV for 5 min. The refinement of Al2Cu phase in Al-Cu alloy is more obvious and more uniform distributed with the increase of UV time. The ultimate tensile strength (UTS), yield strength and elongation of the 1wt% nanosized SiCp/Al-5Cu composites treated by UV for 5 min are increased by 37%, 9.5% and 270% respectively, compared with the untreated composites.
Investigation of Crack Initiation in Glass Substrate by Residual Stress Analysis
Authors: Shinohara Amon , Kobayashi Tatsuya , Shohji Ikuo , Umemura Yuki
Published: December 2018

To investigate the mechanism of crack initiation in the glass substrate, residual stress in the substrate was analyzed by the finite element method (FEM). A Si wafer that has the same mechanical properties of glass was prepared as the substrate. The thin Cu film layer was fabricated on the Si wafer by plating. The warpage of the wafer in the heat treatment process was investigated by laser displacement measurement. Residual stress was calculated by the obtained warpage value using the Stoney formula. It was found that the warpage becomes zero and the stress-free state occurs around at 150°C. On the basis of the FEM analysis result from 150°C to the room temperature in the cooling process, it was found that analyzed warpage values are almost analogous to measured ones. Also, it was confirmed that equivalent stress in the wafer in the vicinity of the Cu/Si interface increases and the stress-concentrated area expands there with increasing the thickness of the Cu film. The results indicates that crack initiation easily occurs in the glass substrate when the thickness of the Cu film increases. Moreover, from the results of the FEM analysis for the warpage of the wafer in the heating process, it was found that the analyzed warpage is good accordance with the measured one from room temperature to around 150°C.
Tensile and Fatigue Properties of Miniature Size Specimen of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge Lead-Free Solder
Authors: Yokoi Masaki , Kobayashi Tatsuya , Shohji Ikuo
Published: December 2018

Tensile and low cycle fatigue properties of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge (mass%) lead-free solder were investigated using miniature size specimens and obtained data were compared to those of Sn-3.0Ag-0.5Cu (mass%). The microstructure of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge consists of dendritic β-Sn phases and ternary eutectic phases surrounding them which are composed of β-Sn, (Cu,Ni)6Sn5 and Ag3Sn. Tensile strength and 0.1% proof stress of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge are superior to those of Sn-3.0Ag-0.5Cu at 25°C and 150°C. However, elongation of it is inferior to that of Sn-3.0Ag-0.5Cu at both temperatures. Fatigue lives of both alloys obey the Manson-Coffin equation and are analogous at 25°C. Although fatigue lives of both alloys decrease at 150°C, the fatigue life of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge is inferior to that of Sn-3.0Ag-0.5Cu. At 150°C, the crack mainly progresses at grain boundaries of recrystallized grains. Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge has several grain boundaies which can be the origin of the crack so that fatigue lives degrade at 150°C.
A Study on Reliability of Pillar-Shaped Intermetallic Compounds Dispersed Lead-Free Solder Joint
Authors: Nakata Yusuke , Kurasawa Motoki , Hashimoto Tomihito , Miki Kenji , Shohji Ikuo
Published: December 2018

A pillar shaped intermetallic compounds (IMCs) dispersed solder joint is a highly durable joint to achieve large area joining. The aim of this study is to investigate the ideal dispersion amount of pillar shaped IMCs. The dispersion rate of pillar shaped IMCs depend on the joining temperature. Pillar shaped IMCs dispersion rates are 3.5% and 5.5% when the joining temperature are 300 °C and 330 °C, respectively. Longitudinal elastic modulus are improved by forming pillar shaped IMCs. As a result of examination of the durability by the thermal cycle test, the durability of the joint with the dispersion rate of 3.5% was similar to that without pillar shaped IMCs, while that with the dispersion rate of 5.5% was remarkably improved. In the case of the dispersion rate of 3.5%, pillar shaped IMCs unevenly distributed and cracks tend to progress. On the other hand, in the case of the dispersion rate of 5.5%, pillar shaped IMCs were uniformly dispersed throughout the joint and suppressed crack propagation. Comparison of durability between pillar shaped IMCs solder and indium added solder to verify the effect of pillar shaped IMCs demonstrated that pillar shaped IMCs solder were more durable than indium added solder.
Effect of Annealing Conditions on the Dissolution Process of Complex Carbonitrides in a V-Nb-Ti Microalloyed Steel
Authors: Basanta Gloria , Rivas Ana L. , Díaz Ervis , Parra Carlos
Published: December 2018

The present work has been undertaken to assess the evolution of dissolution process of large dendritic precipitates in a V-Nb-Ti microalloyed steel. The study was performed by reheating the samples at 1250°C, simulating the industrial reheating practices at laboratory scale and in situ, following industrial profile; afterwards the samples were quenched in 10%NaCl aqueous solution. The characterization of the material was carried out by scanning electron microscopy accompanied with dispersive energy spectrometry, and chemical analysis by inductively coupled plasma optical emission spectrometry. The results showed a partial dissolution of dendritic precipitates. This process ocurred by a progressive dissolving the Nb-rich shells formed over cuboidal particles and primary arm of well-faceted dendritic precipitates, and by fragmentation and spheroidization of secondary branches. These processes gave rise to spherical Nb rich precipitates and cuboidal particles at the reheating conditions used in this study. Both type of particles contain vanadium.
Cross-Correlation Analysis of Fluctuations of Interactions between Nanoparticles and Low Pressure Reactive Plasmas
Authors: Zhou Ren , Mori Kento , Ohtomo Hiroshi , Yamashita Daisuke , Seo Hyun Woong , Itagaki Naho , Koga Kazunori , Shiratani Masaharu
Published: December 2018

We analyzed fluctuations of interactions between low pressure reactive plasmas and nanoparticles formed in the plasmas, to shed light on origins of fluctuations of interactions and to control fluctuations in plasma processes. Spatiotemporal fluctuations of nanoparticle density develop not only in a linear way but also in a nonlinear way. The results suggest nonlinear interactions potentially induce spatial and temporal process fluctuations.
Towards Additive Manufacturing: Pumping Flow Rate with Time-Dependent Material Rheology in 3D Cementitious Material Printing
Authors: Liu Zhi Xin , Li Ming Yang , Wong Teck Neng , Tan Ming Jen
Published: December 2018

3D printing has been getting increasing attention from both industry and academy in recent years. Unlike traditional construction processes, 3D cementitious material printing requires more accurate control on the pumping flow rate, which is known to be affected by the material rheology. In this paper, the effect of fresh rheology on the flow rate of cementitious material was studied experimentally in 3D cementitious material printing process. The material viscosity was measured via a large gap vane viscometer at different time points after mixing, and printing tests were conducted at the same time period to measure the flow rate based on volume conservation principle. Experiments showed that the flow rate was significantly affected by rheology change with respect to time. An open loop control method was then implemented to harmonize the flow volume per unit length during printing processes to improve printing quality.
Nickel Supported Modified Ceria Zirconia Lanthanum/ Praseodymium/Yttrium Oxides Catalysts for Syngas Production through Dry Methane Reforming
Authors: Liu Hong Rui , Świrk Katarzyna , Galvez Maria Elena , da Costa Patrick
Published: December 2018

Dry methane reforming (DRM) has recently received considerable attention as a perspective CO2 utilization technology allowing the valorization natural gas and biogas. The commercialization of the DRM process depends on the use of more stable and active catalysts. The nickel-based catalysts are commonly used in the DRM reaction as they are effective in hydrogen production and nickel is a less expensive material compared to noble metals. However, Ni-based catalysts undergo fast deactivation. The stability of nickel catalysts in DRM reaction may be enhanced by introduction of supports or promoters with basic and/or redox properties. Thus, in this work, Ceria-Zirconia supports were modified by rare earth metals such as Lanthanum, Praseodymium and Yttrium in order to stabilize the raw materials and to promote the catalytic activity. Nickel was then impregnated on such supports and the modified catalysts were tested in dry methane reforming for syngas production since it was already reported that a promotion with nickel and yttrium lead to better activity in DRM catalytic tests over mesoporous materials. All promoted catalysts were characterized by the means of SBET, XRD, TEM, H2-TPR, CO2-TPD in order to define the physical, textural and chemical properties. The influence of basicity on the catalytic activity was clearly evidenced. Moreover, the influence of Nickel loading was also studied. It was evidenced that an optimal Ni loading is needed in order to reach higher activity and stability in DRM.
A Theoretical Analysis of the Rheological Parameters Associated with DDRX
Authors: Montheillet Frank , Piot David
Published: December 2018

The macroscopic strain rate sensitivity m and apparent activation energy Q are derived from their microscopic counterparts associated with strain hardening, grain boundary mobility, and nucleation rate in the case of steady state discontinuous dynamic recrystallization (DDRX). The case of solid solutions, involving effects of the solute concentration on strain hardening and boundary mobility, is also taken into consideration. Moreover, three distinct Derby exponents are introduced to refine the correlation between steady state flow stress and average grain size. Hot torsion data and micrographic observations on a set of nickel-niobium alloys are used to assess the predictions of this tentative approach.
Forensic Analyses of Stress-Strain Diagrams to Evaluate Contributions from Microstructure
Authors: Saimoto Shigeo , Langille Michael R. , Niewczas Marek
Published: December 2018

The conventional characterization of work-hardening is to approximate the stress-strain diagram using the empirical curve-fitting of Hollomon or Voce. The new method uses the Taylor slip analyses to derive a functional form which is optimally fitted to the data. This constitutive relations analysis (CRA) duplicates the data using at least two fit loci. The fit parameters relate to the slip motion within the microstructure and hence its interpretation reveals the possible dynamic shape-change reactions. The fit-process defines a new yield stress which separates the yielding from the deformation mechanisms at large strains that breaks up into two regions separated by intersection parameters. The applications of CRA to nanovoid formation and growth leading to ductile failure, plane stress yield locus prediction using tensile tests and decoding the stress-strain diagram for age-hardened aluminum alloys have been successful. Using super-pure aluminum, this study confirms that CRA is based on crystal plasticity principles and that CRA can predict the correlation of the obstacle strength factor, α, with work-hardening, hence permitting conversion of flow stress at given strains to obstacle density. The derived results show that the inherent annihilation process and the changing strength factor are coordinated to result in a self-consistent constitutive relation.
Multiscale Approach for the Modeling of Chemo-Magneto-Thermo-Mechanical Couplings – Reversible Framework
Authors: Hubert Olivier , Labernhe-Taillard Karine , Fall Mame-Daro , Chang Xu Yang , Savary Maxime , Sevestre Olivia
Published: December 2018

We focus in this paper on a multiscale modeling approach of the materials’ reversible behavior involving couplings of the chemo-magneto-thermo-mechanical type. It is shown that it is possible to take into account a large variety of these coupled environments by a unified approach using the springs of the scale change and the build of an appropriate Gibbs free energy function. The approach is well suited to situations where some fields can be considered homogeneous at a relevant scale and where free deformation can be defined.
On the Challenges and Prospects of the Superplastic Forming Process
Authors: Jarrar Firas , Sorgente Donato , Aksenov Sergey A. , Enikeev Farid
Published: December 2018

Superplastic forming has already been proven as a practical solution for manufacturing lightweight components in niche applications such as the aerospace and luxury cars industries. The demand to produce such components will continue with the limited nature of the energy resources available today. Therefore, superplastic materials are expected to stay as potential candidates in such applications. In addition, superplastic forming offers many unique advantages over conventional forming techniques including greater design flexibility, relatively low tooling cost, and no spring back. However, the full potential of the process has not yet been fulfilled due to concerns about the nonuniformity of the produced parts thickness profiles and the need for heating to achieve the superplastic properties of the material. In this paper the authors address the main challenges that hinder the wide spread of the process. It is of great practical importance, for example, to develop accurate simulations of the superplastic forming process. Such simulations are required for identifying the optimum process parameters for high quality components. The results of any such simulations or experimental investigations should be translated into simple and clear industrial guidelines. In addition, they discuss the current trends and the prospects of this process.
Proving the Preclusion of Data Manipulation Using Parallel Data Acquisition in Chromatography
Authors: Marehn David Thomas , Wilhelm Detlef , Pospisil Heike , Pizzoferrato Roberto
Published: December 2018

Traceability has an enormous value for companies, but especially for those working in the regulated environment. It plays a special role in the field of pharmacy with respect to manufacturing, controlling and distributing batches of drugs. Through the guidance of Good Manufacturing Practice (GMP) traceability should be ensured. An increasing number of pharmaceutical companies are member of one of the global pharmacopoeias (United States Pharmacopeia, European Pharmacopeia and Japanese Pharmacopeia). The specifications of these pharmacopoeias describe the best practice in documentation, control, qualification and risk management. But however, the pharmacopoeias are written very generally and do not distinguish between the vendors of the analytical instruments. Here, we analyze how chromatographic analyses and data acquisition rely on a specific vendor of the device and the chromatography data system (CDS), the controlling software. We present a way to compare the data acquisition of different CDSs communicating with HPLC instruments. A newly developed software called Data Collector allows the acquisition of data from a HPLC detector parallel to the controlling CDS in the same run. Two HPLC systems and two different CDSs using a well defined sample standard have been tested. The direct comparison of the acquired data precludes unexpected data manipulations of both tested CDSs and shows that there are primarily deviations between the CDSs due to time variations only which depend on the sampling rate. All in all the Data Collector can be used for the traceability of data acquisition.
Study of Consistency between Two-Dimensional, sin2ψ, cosα and Fourier Transformation Methods for X-Ray Residual Stress Measurement by Debye Ring Simulation
Authors: Imafuku Muneyuki , Ishikawa Yuki
Published: December 2018

We investigated the consistency of four methods by analyzing the distorted Debye rings with various stress states. Firstly, the distorted Debye rings were generated under various uni-, bi-and tri-axial stress states by using the fundamental stress-strain relationship in two dimensional X-ray stress analysis theory. Secondly, we performed reverse analysis of stress states in the frameworks of sin2ψ and cosα methods from the simulated Debye rings. Moreover, the profiles of simulated Debye rings were Fourier transformed and the stress states were calculated in accordance with the obtained 1st and 2nd order Fourier coefficients. As a result, it was confirmed that all these methods provide the same stress values. That is to say, all these methods are consistent. Therefore, we can guarantee the validity of choosing any appropriate method considering the geometrical restrictions of experiment.
Recycle Processor for Commercial Aircraft Wing Trimmings
Authors: Johnson Craig , Morrow Jason , Minasyan Misha
Published: December 2018

Tons of composite trimmings are regularly generated as a result of current production methods in commercial aircraft wing component fabrication. Specific to this proposal, a local facility produces trimmings that range in thickness from about a centimeter to over two inches thick and varying widths from a few inches to six inches and lengths up to five feet. Reducing the cost of the disposition of these trimmings and a reduction of waste to landfill are the primary motivations for this work. A processor was devised that both separates fiber and reduces volume. This device is a vertical crusher/roller into which the ‘boards’ are inserted. An initial cogged wheel delaminates much of the board. Secondary wheels and hammers crush the matrix. The resulting matrix is captured at the bottom, while the fibers are pulled off to a side roller. Preliminary testing of a prototype indicates that a composite board takes 156 ksi to initiate delamination in bending. A sub-size device with components was designed and built. The device was designed in the fall of 2017 and constructed over the winter. By spring the system was operational and test data was generated for the processor. Test parameters include percent and amounts of recovered fiber, processing rates related to all the composite constituents, packing volumes, and overall energy management. A report was generated in concurrence with our MET489 Senior Project capstone course by the end of the current academic year.
Fabrication and Validation by Micromilling for Bioreactor Prototyping
Authors: Böhme Andrea , Schütze Felix , Sauer Sabine , Foitzik Andreas H.
Published: December 2018

Bioreactor systems for cultivating cells in Life Sciences have been widely used for decades. Recently, there is a trend towards miniaturization, disposables and even micro platforms that fulfill increasing demands strongly aiming for production and testing of novel pharmaceutical products. Miniaturized bioreactors allow low power consumption, portability and reduced space requirements and utilize smaller volumes of reagents and samples [1,2]. A recursive strategy is necessary for optimizing the design and the manufacture of such miniaturized bioreactors. For the fabrication of these prototypes utilized micro-milling. Micro milling is a mechanical process which is commonly applied to create micro-structures in metals, e.g. aluminum and steel, or polymers, e.g. poly carbonate substrates. The structures and geometries are generated by utilizing computer aided design. By means of computer-aided manufacturing, the machining operations are implemented and then transferred to the machine tool. The machine tool moves the cutting tools with certain speeds, feeds and traverse ranges to the substrate. Micro milling has the advantage that the materials are generally not degraded by chemical substances, heating procedures or electromagnetic radiation.