Solidification Properties Research Articles

Viscoplastic characterization of novel (Fe, Co, Te)/Bi containing Sn–3.0Ag–0.7Cu lead-free solder alloy

A novel alloying elements of TeFeCoBi have been anticipated to modify Sn–3Ag–0.7Cu SAC(307) alloys in various attributes. This study inspects the influence of slight/trace addition of Te, Fe, and Co besides 2 wt% Bi on the enhancement of microstructural solidification, thermal behavior, and tensile properties of SAC(307) alloy. Using field emission-scanning electron microscopy (FE-SEM), microstructural analysis indicated that the addition of Te, Fe, Co, and Bi not only inhibited the growth of large platelet Ag3Sn IMC phase, but also the new TeSn, FeSn2, and (Cu, Co)6Sn5 phases together with Co3Sn and Bi particles were formed in the eutectic regions and verified from EDS analysis. The synergetic influence of these precipitates results in significant combination of high strength and large ductility of the new solder. The ultimate tensile strength of the SAC(307)-TeFeCoBi alloy is found to be 58.3 MPa, which is 1.7 times higher than the corresponding of SAC(307) alloy. Moreover, the ductility was improved by ~ 46% with high reliability, which enriched its dissipation ability of plastic energy at various processing situations. The addition of TeFeCoBi elements also markedly increased the undercooling while maintaining the eutectic temperature and pasty range to the same SAC(307) levels.

Effect of Boron Content on Microstructure Evolution During Solidification and Mechanical Properties of K417G Alloy

Effect of Boron Content on Microstructure Evolution During Solidification and Mechanical Properties of K417G Alloy

Geotechnical properties of products of alternative fuel combustion and co-firing with hard coal in the context of their use as solidifying dense mixtures.

Efforts directed to reduction of greenhouse gas emissions have led to the introduction of new firing/co-firing technologies and alternative fuels in the coal-based power industry. This has resulted in the formation of combustion products with new properties that can affect the reuse of these wastes and/or pose a hazard to the environment. One of the power-plant fly ash (FA) reuse options is its application as a solidifying dense mixture with water for backfilling mine workings or in engineering constructions. In this comparative study, geotechnical properties of three groups of FA were evaluated: (i) weathered and freshly generated ash from hard coal combustion in conventional pulverized coal boilers without (C-PCA, C-PFA) and with selective non-catalytic reduction installations for NO x reduction (NC-PFA); (ii) FA from hard coal co-firing with alternative fuels: off gases (GC-PFA) or biomass (BC-PFA) in pulverized coal boilers; (iii) FA from coal (C-FFA) or biomass combustion (B-FFA) in fluidized-bed boilers. The transportability, bonding and solidification properties, uniaxial compression strength, and rewetting of dense mixtures were evaluated by measurements of volumetric density, fluidity, water retention capacity, bonding time, solidification time, uniaxial compression test, and slakeability at the background of the FA chemical composition. Calcareous C-FFA > B-FFA displayed the best geotechnical properties. Other materials showed poorer geotechnical properties than FFA and could be aligned in the order BC-PFA > GC-PFA > NC-PFA > C-PFA > C-PCA.

Coaxial extrusion bioprinting of 3D microfibrous constructs with cell-favorable gelatin methacryloyl microenvironments

Bioinks with shear-thinning/rapid solidification properties and strong mechanics are usually needed for the bioprinting of three-dimensional (3D) cell-laden constructs. As such, it remains challenging to generate soft constructs from bioinks at low concentrations that are favorable for cellular activities. Herein, we report a strategy to fabricate cell-laden constructs with tunable 3D microenvironments achieved by bioprinting of gelatin methacryloyl (GelMA)/alginate core/sheath microfibers, where the alginate sheath serves as a template to support and confine the GelMA pre-hydrogel in the core during the extrusion process, allowing for subsequent UV crosslinking. This novel strategy minimizes the bioprinting requirements for the core bioink, and facilitates the fabrication of cell-laden GelMA constructs at low concentrations. We first showed the capability of generating various alginate hollow microfibrous constructs using a coaxial nozzle setup, and verified the diffusibility and perfusability of the bioprinted hollow structures that are important for the tissue engineering applications. More importantly, the hollow alginate microfibers were then used as templates for generating cell-laden GelMA constructs with soft microenvironments, by using GelMA pre-hydrogel as the bioink for the core phase during bioprinting. As such, GelMA constructs at extremely low concentrations (<2.0%) could be extruded to effectively support cellular activities including proliferation and spreading for various cell types. We believe that our strategy is likely to provide broad opportunities in bioprinting of 3D constructs with cell-favorable microenvironments for applications in tissue engineering and pharmaceutical screening.

Solidification, Microstructure and Mechanical Properties of Mg-2.8Nd-1.5Gd-0.5Zn-0.5Zr Cast Alloy with Erbium Addition

The thermal parameters of Mg-2.8Nd-1.5Gd-0.5Zn-0.5Zr cast alloy with 0.25 wt.% of erbium (Er) were evaluated by the computer-aided cooling curve thermal analysis(CA CCTA), whereas the microstructure analysis was investigated by the optical microscope and scanning electron microscopy. Results from the cooling curve and microstructure analysis showed that Er altered the grain size of the alloys. In addition, the grain size was reduced by approximately 19.6% with the addition of Er. Scanning electron microscopy results showed that Er formed an Mg-Zn-Nd-Er phase which distributed along the grain boundaries. Furthermore, the mechanical properties were investigated by hardness and tensile tests with Er addition. The addition of 0.25 wt.% of Er significantly improved the ultimate tensile strength and yield strength. In addition, the hardness value of Mg-2.8Nd-1.5Gd-0.5Zn-0.5Zr increased by 13.9% with Er addition.

A novel technique for in‐situ manufacturing of functionally graded materials based polymer composite spur gears

The authors propose a different manufacturing process developed to fabricate functionally graded material (FGM) based thermoplastic gear. FGM and homogeneous gears are manufactured by means of an especially designed mould and a punch. The punch acts as an integral rotating member of the mould and has a cavity carved in the shape of gear where the material is filled to produce gears. The punch rotates at 1,800 rpm for 2 min to force at segregation of fibers towards the periphery of the punch cavity because of the centrifugal force in action. Polypropylene (PP) filled with 15 and 30 wt% glass fibers is used to fabricate FGM and homogeneous gears. Unfilled PP gear is also fabricated for comparative study. Gradation in FGM gear is verified by Scanning electron microscope (SEM) analysis and Shore D hardness measured in three different locations of the fabricated FGM gears. Gradation in FGM gear is also verified by ignition loss test method. Continuous gradation is observed in FGM gear by SEM and confirmed by hardness test and ignition loss test. In this work, transmission efficiency of unfilled, homogeneous and FGM PP gears during operation is also investigated and compared. A polymer gear test rig is used for experimental work. This route shows a promising potential for fabrication of FGM based thermoplastics gears which otherwise is difficult to manufacture because of their fast solidification properties at room temperature. POLYM. COMPOS., 40:523–535, 2019. © 2017 Society of Plastics Engineers

Directional Solidification, Structure, and Mechanical Properties of a Eutectic Nb–Si Alloy with a Natural Composite Structure for GTE Blades

Directional solidification in a liquid-metal coolant and the formation of a natural composite structure in a eutectic niobium–silicon alloy are studied to produce GTE blades in ceramic molds. The microstructure and the phase composition of the alloy are analyzed in parts of variable sections. The shortand long-term strengths of the niobium–silicon composite material are measured at a temperature of 1200°C.

Plantar pressure distribution of ostrich during locomotion on loose sand and solid ground.

BackgroundThe ostrich is a cursorial bird with extraordinary speed and endurance, especially in the desert, and thus is an ideal large-scale animal model for mechanic study of locomotion on granular substrate.MethodsThe plantar pressure distributions of ostriches walking/running on loose sand/solid ground were recorded using a dynamic pressure plate.ResultsThe center of pressure (COP) on loose sand mostly originated from the middle of the 3rd toe, which differed from the J-shaped COP trajectory on solid ground. At mid-stance, a high-pressure region was observed in the middle of the 3rd toe on loose sand, but three high-pressure regions were found on solid ground. The gait mode significantly affected the peak pressures of the 3rd and 4th toes (p = 1.5 × 10−6 and 2.39 × 10−8, respectively), but not that of the claw (p = 0.041). The effects of substrate were similar to those of the gait mode.DiscussionGround reaction force trials of each functional part showed the 3rd toe bore more body loads and the 4th toe undertook less loads. The pressure distributions suggest balance maintenance on loose sand was provided by the 3rd and 4th toes and the angle between their length axes. On loose sand, the middle of the 3rd toe was the first to touch the sand with a smaller attack angle to maximize the ground reaction force, but on solid ground, the lateral part was the first to touch the ground to minimize the transient loading. At push-off, the ostrich used solidification properties of granular sand under the compression of the 3rd toe to generate sufficient traction.

Stable solidification of silica-based ammonium molybdophosphate by allophane: Application to treatment of radioactive cesium in secondary solid wastes generated from fukushima

Silica-based ammonium molybdophosphate (AMP/SiO2) is an absorbent material that can effectively remove Cs from radioactive-contaminated wastewater (RCW) generated by Fukushima nuclide accident. Pressing/sintering method was used for final disposal of secondary waste (spent absorbent) to achieve the volume reduction of AMP–Cs/SiO2 (AMP/SiO2 saturation adsorption of Cs) and stable solidification of Cs by adding natural allophane. The structure of AMP–Cs completely collapsed at approximately 700°C, and most Mo and P species in AMP sublimed. The optimal sintering temperature was estimated as 900°C. The stable crystalline phase of Cs4Al4Si20O48 was recrystallized by the reaction of Cs2O, Al2O3, and SiO2, and the immobilization ratio of Cs was approximately 100%. The leachability of Cs from the sintered product in distilled water was approximately 0.41%. The high immobilization and low leachability of Cs were attributed to the excellent solidification properties of the sintered products of AMP–Cs/SiO2–allophane.

Investigation of solidification behavior of the Sn-rich ternary Sn–Bi–Zn alloys

Solidification properties and microstructure of six as-cast Sn–Bi–Zn alloys with 80 at.% of Sn and variable contents of Bi and Zn were experimentally investigated using the scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) and differential scanning calorimetry (DSC). The experimentally obtained results were compared with predicted phase equilibria according to the calculation of phase diagram (CALPHAD) method and by the Scheil solidification simulation.

Sugar 3D Printing: Additive Manufacturing with Molten Sugar for Investigating Molten Material Fed Printing

Abstract Recent breakthroughs in additive manufacturing of molten glass using gravity-fed mechanisms have opened a new area of research in large-scale extrusion of molten material. However, the machines and techniques used for printing molten glass are expensive and complex due to high process temperature (>1000°C). A mixture of sucrose sugar and corn syrup is proposed as an analogous substitution material for research in molten material fed three-dimensional (3D) printing. Molten sugar is optically transparent and it exhibits similar temperature–viscosity relationship and solidification properties as molten glass, but at a much lower temperature (100–150°C). A low cost, desktop size 3D printer is designed with a temperature controlled sugar reservoir made from easily obtainable parts. The process of printing with molten sugar is demonstrated with success in recreating objects with similar complexity to glass prints. The techniques described in this study can be implemented easily for future investigation...

Solidification Analysis in Permanent Mould Casting of Aluminium Alloy LM6 Reinforced Titanium Carbide Particulates Metal Matrix Composites

Permanent mould casting was used as the production technique to produce the metal matrix composites (MMCs) specimens. Thermal measurements during the casting process were recorded. Based on these data, solidification graphs were plotted to understand the solidification characteristics. Solidification analysis was performed by interpreting the parameters drawn from the solidification graphs. Parameters such as; nucleation primary alpha phase temperature, liquidus arrest temperature, eutectic growth temperature and solidification time were identified. The results showed that addition of titanium carbide particulates (TiCp) into the aluminium-11.8% silicon alloy (LM6) have affected various time and temperature parameters of its solidification properties. These in turn will have an influence on the mechanical property of the MMCs.

Evolution of coal ash solidification properties with disposal site depth and age, 'Gacko' Thermal power plant case

Ash with high calcium content is produced by coal combusting in 'Gacko' thermal power plant (Bosnia and Herzegovina). Result of controlled mixture of water and ash is spontaneous ash solidification on disposal site. Speed and solidification efficiency depends on content of calcium-oxide in ash and water: ash mass ratio, which was determined by previous research. Mass ratio that was chosen as the most suitable ratio for industrial usage (roughly) was 1:1. Samples of ash of different age were taken after 6.5 years of exploitation and their chemical, physical, mineralogical and geotechnical characteristics were analyzed. Disposed ash was stratified and very heterogeneous. It was shown that great impact on solidification process in practice have climate conditions, proper handling slurry processing, work continuity and disposal site preparation. Great impact of water is noticed which is, because of its water permeability filtrated into lower layers and significantly alters it characteristic.

Reworkable adhesives composed of photoresponsive azobenzene polymer for glass substrates

ABSTRACTA reversible isothermal phase transition between the liquid and solid states in response to light irradiation was achieved in side chain-type azobenzene polymers. These materials can be used as adhesives that are detachable without applying any mechanical and thermal stress but also repeatedly reworkable because of their photoinduced liquefaction and solidification properties. The adhesive strength to glass plates was more than 3 MPa in single lap shear tests. This value is three times higher than previously reported and is sufficiently strong for glass substrates.

Molten and solidification properties of copper nanoparticles

Molten and solidification properties of copper nanoparticles

Prediction of solidification behaviour and microstructure of Ni based alloys obtained by casting and direct additive laser growth

Numerical tools are now used widely in the prediction of material properties necessary in order to gain a better understanding of the relationship between material properties and performance, to improve the reliability of processes and the quality of the final product, and to reduce costs, waste and energy use. In this paper, the solidification properties and the microstructure of some commercial Ni based alloys were analysed and predicted numerically using the ProCAST software. The microstructure of a sample obtained by the direct additive laser growth, a new additive manufacturing technique based on the selective laser melting, is presented and discussed. Numerical approaches and software packages that can be used to model additive manufacturing processes are discussed and critically analysed.

Solidification properties and microstructure investigation of the as-cast Sn-rich alloys of the Sn-Sb-Zn ternary system

Solidification properties and microstructure investigation of the as-cast Sn-rich alloys of the Sn-Sb-Zn ternary system

Study on the microstructure and liquid–solid correlation of Al–Mg alloys

ABSTRACTBased on the available structural models and theories of electrical resistivity (ER) of liquid alloys, the structure and the liquid–solid correlation of Al (100-x) Mgx (x = 0, 10, 20, 30, 40, 50) alloys have been qualitatively studied by measuring the ER during the heating/cooling process using the direct-current (DC) four-probe method, as well as by characterizing the solidification morphology and testing the hardness. The result shows that the ER of Al–Mg alloys increases with the increasing temperature and the Mg content; thermal state and history have an effect on the solidification structure and properties: the ER of Al–Mg alloys exhibits a lag phenomenon of structure change during the heating/cooling process. A higher heating/cooling rate contributes to the more obvious relaxation effect of ER and the more uniform structure. Furthermore, higher pouring temperature (PT) leads the melts and solidification structure to be more homogeneous, which increases the hardness.

Effect of Process Parameters on Solidification Structure and Properties of Laser Deposited SS316 Alloy

LENS™ is one of the laser additive manufacturing techniques for depositing metal powders directly using 3D CAD model to produce functional parts. The effect of process parameters on microstructural features, solidification cracks, hardness, and tensile properties of SS316 alloy were studied. The effect of re-melting of each layer partially during deposition of successive layers was also investigated. The tensile properties of LENS deposited SS316 alloy were found to be superior to wrought alloy.

Austenite dendrite morphology in lamellar graphite iron

Primary austenite has been underestimated in general when the theories of nucleation, solidification, microstructure formation and mechanical properties were established for cast iron and particularly for lamellar cast iron. The present work aims to investigate the primary austenite morphology of as cast samples of a hypoeutectic lamellar cast iron produced with different cooling rates. Morphological parameters as the area fraction primary austenite, the secondary dendrite arm spacing, the dendrite envelope surface, the coarseness of the primary dendrite expressed as the relation between the volume of the dendrite and its envelope surface and the coarseness of the interdendritic space also known as the hydraulic diameter are measured. Furthermore, the role of the size of the investigation area is revealed to be sequential investigation. A strong relation between all measured morphological parameters and the solidification time has been established, except the volume fraction of primary austenite, which is constant for all cooling conditions.