Conventional Melting Process Research Articles

Application of Solution Calorimetry to the Prediction of 20.15[(2.038 + x)SiO<sub>2</sub>-(1.457 － x)Na<sub>2</sub>O]-2.6-P<sub>2</sub>O<sub>5</sub>-26.95CaO Glass Bioactivity

Bioactive glasses in the system SiO2-Na2O-CaO-P2O5 were prepared by the conventional melting process at a high temperature in an electric furnace. The densities of the glasses as well as their glass transition temperatures were measured experimentally. Also, the glasses were characterized by solution calorimetry at 298 K in an acidic solvent consisting of HF (6 M) and HNO3 (4 M). A simulation of the bioactivity properties of these obtained glasses was carried out by thermodynamic calculations, with the purpose of understanding the in vitro results obtained.

Preparation of expanded graphite/poly (phenylene sulfide) composites with high thermal and electrical conductivity by rotating solid-state premixing and melt processing

A simple and effective method to add large amounts of expanded graphite (EG) to poly (phenylene sulfide) (PPS) was developed. Before conventional melt processing, solid-state PPS and EG powders were mixed using high-speed rotation. In this way, the loose and porous vermicular structure of EG could be effectively destroyed and partly exfoliated, which made EG easy to be adsorbed on the surface of the PPS powders. This was extraordinarily helpful to achieve good dispersions of EG during the subsequent melt mixing even at high loading, which was difficult to achieve by conventional direct melt mixing. As a result of the good dispersions and strong interactions, the EG/PPS composites prepared showed a dramatically improved thermal conductivity (15.8 Wm−1K−1) and electrical conductivity (125.3 Sm−1) as the addition of EG reached 60 wt%.

Thermoplastic Cellulose Propionate-graft-Poly(L-lactide) Copolymers Homogeneously Synthesized by "One Pot" Process from Native Cellulose

Using native cellulose as the starting materials and 4-dimethylaminopyridine(DMAP) as the catalyst,a series of novel cellulose propionate-graft-poly(L-lactide) copolymers(CP-g-PLAs) was synthesized in an ionic liquid AmimCl via "one pot" process.DMAP can effectively catalyze the propionylation of cellulose with propionic anhydride and the subsequent ring-opening grafting copolymerization of L-lactide(LA) from residual hydroxyl groups in cellulose.The structure of CP-g-PLA copolymers could be well controlled by changing the molar ratio of propionate hydride/cellulose and LA/cellulose.When PLA content above 27.46%,the copolymers exhibited thermoplastic behavior and could be shaped by conventional melt processing methods,such as injection molding.

Structure and Properties of Fe-Ni-Al-Si Alloys Produced by Powder Metallurgy

Reactive sintering powder metallurgy is a simple alternative to conventional melting and powder metallurgy processes. During this process, pressed powder mixture of pure metals or other precursors is transformed into bulk intermediary phases by thermally activated in situ reaction. This process was previously tested on Fe Al and Fe Al Si alloys. Positive e ect of silicon on the reactive sintering behaviour was determined, leading to the development of novel carbon-free high-silicon FeAl20Si20 alloy (given in wt%). In this work, the e ect of nickel on the pressureless reactive sintering of Fe Al Si pressed powder mixtures was studied. To explain the nickel in uence, di erential thermal analysis was utilized. Microstructure, phase composition and porosity of the FeAl20Si20Nix (x = 0, 5, 10, 20 wt%) alloys was described. Hardness, wear resistance, high-temperature oxidation resistance and thermal stability were evaluated as functions of nickel content. Results showed that porosity decreases with growing nickel content down to less than 3 vol.%. Oxidation rate of these alloys is more than 10 times lower than that of original FeAl20Si20 alloy. Thermal stability and abrasive wear resistance of these alloys is also superior to Fe Al and Fe Al Si materials.

Soda-based glass fabricated from Thailand quartz sands doped with silver compound

Yellow colored glass which used for luxury art glass in ancient time was fabricated by the addition of silver compound into the molten glass. It was proved that it was actually silver nanoparticle technology. In this work, the SiO2–(Na2O,K2O)–CaO–B2O3–Al2O3–MgO glass system was prepared in the laboratory scale based on local quartz sands from Trat Province, eastern area of Thailand as the silica raw material. Various concentrations of silver nitrate were added. After the complete conventional melting process, the bubble-free yellow glasses were yielded. Physical and optical properties such as density, refractive index and optical absorption spectra were measured. Scanning electron microscope coupled with energy dispersive spectroscopy was carried out to study their morphology. The refractive indices and densities were increased as the increase of the silver contents. Electron micrographs showed the presence of silver nanoparticle in the glass matrix. UV–VIS spectra were in good agreement with that found from SEM measurements and corresponded with the universally accepted. It was also showed that the more brilliance on the surface of the glass products was obtained after firing with a gas torch.

An alternative method for processing high viscosity polymers. I. Development and feasibility study

AbstractUltrahigh molecular weight polymers generally exhibit very high melt viscosities. They are therefore very difficult to process and require heavy‐duty processing equipment. In some cases they cannot be processed at all using conventional melt processing techniques. In this study, a novel processing method called Thermoflow Forming (TFF) has been developed for manufacturing parts made from high viscosity polymers. The TFF process is based on the flow of polymer material in its thermoelastic state, between its glass transition and melting temperatures, by compressive flow thermoforming. The processing equipment consists of an upper and lower mold tool, which may be driven together, while its temperature is controlled through either induction heating or air cooling. Parts with both constant and varying wall thicknesses were successfully manufactured from ultrahigh molecular weight polyethylene and polytetrafluoroethylene (PTFE). Despite the significantly different wall thicknesses molded, the parts showed minimal warpage and no voids. Those made from PTFE exhibited a fibrillated morphological structure whose size and orientation depended on the material flow direction. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Reduction of Energy Consumption and GHGs Emission in Conventional Sand Casting Process by Application of a New CRIMSON Process

In conventional foundry, engineers generally consider the quality of casting part as the most essential issue and regard the energy consumption and Green House Gas (GHGs) emission as the auxiliary ones. This usually causes large amount of energy consumption as a result of the inefficient casting processes used and increases the production costs and environmental pollution. This paper presents the new CRIMSON process where its facility and melting process were compared with conventional melt furnaces and aluminium alloy melting process. An actual case was investigated to reveal quantitatively how the conventional foundry wastes energy and increases GHGs emission, and what the improvement of energy efficiency and the GHGs emission reduction can be achieved using the new CRIMSON process. The results of this investigation will help the foundry engineer recognize the importance of energy saving and environmental protection and show how to utilise this new process to reduce production costs and carbon footprint without decreasing the quality of the cast part. Key words: Energy consumption; GHGs emission; Furnace; Aluminium; Sanding casting; Melting; CRIMSON

Low Temperature Sintering of Innovative Bioactive Glasses

Two innovative glass compositions based on the commonly used 45S5Bioglass®were developed by increasing the calcium quantity and replacing the sodium oxide with a specific content of potassium oxide. The new glasses, namedBG_Ca/KandBG_Ca/Mix, can be prepared using a conventional melting process and show a very low tendency to crystallize. Thanks to this peculiarity,BG_Ca/KandBG_Ca/Mix powders can be sintered at a relatively low temperature (800°C) to obtain samples of high compactness and bioactivity, since their amorphous nature is preserved. Consequently, the proposed glasses are perfect for making specific products such as scaffolds or hydroxyapatite‐based composites. Furthermore, the relatively low alkali amount in the new compositions gives rise to a slow ion leaching in simulated body fluid, thus avoiding abrupt changes inpHthat can damage osteoblasts or negatively affect their behavior.

Super broadband yellow emission glass suitable for white lighting

We present a new glass able to produce ultra-broadband yellow fluorescence. The luminescence system is Ce3+ doped low silica calcium aluminosilica glass excited by blue light emitting diode (LED). The glass is prepared by the conventional melting process. We analyze the luminescence properties of the samples by measuring their absorption spectra, excitation spectra, fluorescence spectra. Furthermore, we study the influence of excitation wavelength on the fluorescence intensity and peak wavelength. The doped glass combined with blue LED to obtain the white lighting is achieved. Besides we calculate the Commission Internationale de I'Eclairage chromaticity coordinate. Therefore these glasses have large potentials to be used as white lighting phosphor materials.

Confinement of Elastomeric Block Copolymers via Forced Assembly Coextrusion

Forced assembly processing provides a unique opportunity to examine the effects of confinement on block copolymers (BCPs) via conventional melt processing techniques. The microlayering process was utilized to produce novel materials with enhanced mechanical properties through selective manipulation of layer thickness. Multilayer films consisting of an elastomeric, symmetric block copolymer confined between rigid polystyrene (PS) layers were produced with layer thicknesses ranging from 100 to 600 nm. Deformation studies of the confined BCP showed an increase in ductility as the layer thickness decreased to 190 nm due to a shift in the mode of deformation from crazing to shear yielding. Postextrusion annealing was performed on the multilayer films to investigate the impact of a highly ordered morphology on the mechanical properties. The annealed multilayer films exhibited increased toughness with decreasing layer thickness and resulted in homogeneous deformation compared to the as-extruded films. Multilayer coextrusion proved to be an advantageous method for producing continuous films with tunable mechanical response.

Preparation and Characterization of CaF<sub>2</sub> Doped Bioglass Ceramics

Bioglass Ceramics having molar composition 40SiO2-(44-X)CaO-10MgO-6P2O5-XCaF2 (where X = 0 to 8%) were prepared by conventional melting process in an electric globar furnace at 1400±10°C. Controlled crystallizations were carried out to convert the bioglasses to their corresponding ceramics. Nucleation and crystallization regimes were carried out by differential thermal analysis. The crystalline phases termed hydroxy fluoroapatite, akermanite and wollastonite were identified by using x-ray diffraction analysis. The investigation of bioactivity for the prepared glass and glass ceramics was done by infrared absorption and infrared reflection spectra after immersion in simulated body fluid (SBF) for different periods at 37.8°C. Scanning electron microscope (SEM) analysis was carried out to investigate the surface texture. Micrographs show the formation of HCA layer on the surface of the bioglass ceramics samples after 7 days of SBF treatment. The surfaces of the samples were completely covered with irregular and needle-like aggregates of Ca–P layer. The released ions were estimated by atomic absorption spectroscopy. The chemical durability of these materials was determined by pH measurement methods and it was found that pH of the solution increases up from 1 to 7 days. Further, pH decreases with increasing time period, from 15 to 30 days in SBF solution.

Novel Polypropylene/Inorganic Fullerene-like WS2 Nanocomposites Containing a β-Nucleating Agent: Dynamic Crystallization and Melting Behavior

The dynamic crystallization and melting behavior of isotactic polypropylene-tungsten disulfide (iPP/IF-WS(2)) nanocomposites incorporating a β-nucleating agent is investigated by X-ray diffraction and differential scanning calorimetry. A conventional melt-processing strategy is employed to generate new materials that exhibit variable α and β polymorphism under the appropriate kinetic conditions. The results show that when the dual additive system is employed the nucleation ability on isotactic polypropylene not only depends on the nucleation efficiency (NE) and relative content of the individual α and β-nucleating agents, but also on the cooling rates employed. The nucleating behavior of the additives is explained by competitive nucleation, and the correlation between crystallization and melting temperatures and relative content of α and β-crystals of iPP in the nanocomposites is discussed.

Thermal Desorption of Hydrogen from Mg<SUB>2</SUB>Ni Hydrogen Storage Materials

In order to investigate the influence of HCS on the hydrogen occupation site of Mg2Ni alloy, the thermal desorption technique has been applied to Mg2Ni hydride made by hydriding combustion synthesis (HCS). Mg2Ni was made under low temperature in a short time by the HCS compared to conventional melting process. At various initial hydride wt% from 0.91 to 3.52, the sample was heated to 623 K at a rate of 1.0 K/min. The starting temperature of the evolution of hydrogen goes higher as the initial hydride wt% increases. Only one peak is shown in the case of the small initial hydride wt%. But two peaks appeared with increasing initial hydride wt%. The activation energies obtained by the first and second peaks are 113.0 and 99.5 kJ/mol respectively. The two site occupation model by Darriet et al. was proved. The influence of HCS on the hydrogen occupation site of Mg2Ni alloy is nonexistent.

Thermoelectric Properties of Spark Plasma-Sintered In4Se3-In4Te3

We report the thermoelectric properties of spark plasma-sintered In4Se3-In4Te3 materials. For comparison, pure In4Se3 and In4Se3 (80 wt.%)/In4Te3 (20 wt.%) mixture samples were prepared. In4Se3 and In4Te3 powders were synthesized by a conventional melting process in evacuated quartz ampoules, and a spark plasma method was used for the sintering of the pure In4Se3 and mixture samples. Thermoelectric and structural characterizations were carried out, and the mixing effect of In4Se3 and In4Te3 on the thermoelectric properties was investigated.

Micro/Nano Structure and Morphology of Multi-Phase Polymer/Oxide Composites Prepared by Powder Melt Processing

ABSTRACTPowder polymer processing techniques were evaluated as a means to generate homogeneous immiscible polymer blends without the high residence times at elevated temperature and high shear rates required by extrusion. Using emulsion polymerized and cryogenically jet pulverized PMMA and HDPE powder precursors, blends were prepared with morphologies comparable to extruded blends. Advanced EDS imaging methods combined with SiO2 marker spheres enhanced electron imaging and analysis of all blend phases. These processing methods will be useful in producing polymer blends from fragile polymers, such as those used in biomedical applications, that cannot tolerate the temperature or shear rates of conventional melt processing.

Control of Thermoelectric Properties through the addition of Ag in the Bi0.5Sb1.5Te3Alloy

In this study, the thermoelectric properties of the Ag-doped Bi0.5Sb1.5Te3 compounds were investigated in the temperature range from 323 K to 573 K. Ingots were fabricated by a conventional melting process and the powder crushed from ingots was then sintered using a hot-pressing method. The temperature dependence of the Seebeck coefficient and the electrical conductivity of the Ag-doped Bi0.5Sb1.5Te3 compound are characteristic of degenerate semiconductors, which is fairly different from the conventional Bi0.5Sb1.5Te3 compound. The power factor (α2σ) of the quaternary compound was larger than that of the ternary, which is mainly due to the increase in the electrical conductivity with doping content of Ag. The thermal conductivity was greater than that of the Ag-free Bi0.5Sb1.5Te3 compound in the temperature range from 323 K to 523 K. The lattice thermal conductivity showed low values throughout the temperature range. The maximum value of the dimensionless figure of merit (ZT) of the 0.05 wt. % Ag-doped compound and the ternary alloy were 1.2 at 373 K and 0.88 at 323 K, respectively. Each of the maximum peak ZT shifts to a higher temperature region with increases in the doping content of Ag. This is likely due to the control of the lattice thermal conductivity by the twin structure, which had a nano-ordered layer.

Effects of Ni addition on hydrogen storage properties of Mg 17Al 12 alloy

The present study reports the effect of Ni addition on the structure and hydrogen storage properties of Mg 17Al 12 alloy. The Mg 17Al 12 is synthesized by conventional melting process, and then ball-milled with Ni powder to form Mg 17Al 12– X wt.% Ni ( X = 0, 10, 20) alloys. XRD results showed that the formation of stable Al 3Ni and Al 3Ni 2 phases in the Ni-containing alloys after hydrogenation results in the production of surplus Mg during the desorption process. The catalytic effect of surplus Mg on the Ni-containing alloy is responsible for an enhancement of the hydrogen capacity and absorption rate, compared with ball-milled Mg 17Al 12 below 300 °C.

Microstructures and Thermoelectric Properties of Spark Plasma Sintered In4Se3

We report microstructures and thermoelectric properties of In4Se3 thermoelectric materials. In4Se3 powder was synthesized by conventional melting process in evacuated quartz ampoules and sintering of In4Se3 was performed by spark plasma method at various sintering temperature. The microstructure and density of the sintered body of In4Se3 were strongly dependent on the sintering temperature. Thermoelectric properties, such as electrical conductivity, Seebeck coefficient and thermal conductivity, were also characterized and the effects of the sintering condition on the thermoelectric properties were investigated.

Characterization of 150mm in Diameter NiTi SMA Ingot Produced by Electron Beam Melting

Earlier works showed that NiTi shape memory alloy production by electron beam melting (EBM) is a viable process in which its main characteristic is the low contamination by impurities such as carbon and oxygen. Some difficulties arise when compared to conventional vacuum induction melting (VIM) process such as composition control and complex machine operation. This work focus on the production of ever made large scale 150mm in diameter NiTi ingot produced by EBM showing its viability. The carbon contamination was only 0.016wt% compared to usual 0.05wt% of VIM process. The ingot radial composition homogeneity was proved by small variation presented by direct and reverse peak martensitic transformations temperatures which was around 2°C.

Where reactive sintering beats melt technology

Bulk intermediary phases of titanium-aluminium and titanium-aluminium-silicon systems are promising materials for high-temperature applications. However, their production by melt metallurgy is problematic due to high melting points of the intermediary phases and high reactivity of the melt. Reactive sintering via powder metallurgy is a simple alternative to conventional melting processes, say Czech researchers…