Rotation Cylinder Method Research Articles

Viscosity measurement and prediction of gasified and synthesized coal slag melts

The viscosity of gasified and synthesized coal slag melts for homogeneous liquid state was measured in air by rotation cylinder method with the viscosity range of 0.2–15Pa·s in the temperature range 1300–1650°C. The viscosity decreased monotonically with increasing temperature for all samples. The viscosity of AD slag melt with relatively-high Fe2O3 (∼8mol%) and low SiO2 (∼40mol%) contents rapidly increased with decreasing temperature from 2Pa·s at 1350°C to ∼10Pa·s at 1300°C presumably due to crystallization. The viscosity of gasified coal slag melts increased with increasing contents of Al2O3 and SiO2 and decreased with increasing contents of CaO, MgO, FeO, and Fe2O3. The roles of these main components on melt viscosity are classified into network former (NWF) and modifier (NWM). Two types of amphoteric oxides: Al2O3 and Fe2O3 play different respective roles of NWF and NWM on viscosity for gasified and synthesized slag melts in CaO–MgO–Al2O3–FeO–Fe2O3–SiO2 system. A parameter relating to the total contents of NWF and NWM is proposed to predict the viscosity of slag melts at high temperatures from chemical composition.

The Dissolution Kinetics of Al2O3 into Molten CaO-Al2O3-Fe2O3 Slag

The rotation cylinder method was used to investigate the dissolution kinetics of Al2O3 into molten CaO-Al2O3-Fe2O3 slag, and weight losses of the Al2O3 rod were selected as experimental variables. The final melt was milled into powders for XRF detection, and the Al2O3 rod with adhesive melt after experimental was examined by scanning electron microscopy and energy dispersive spectrometer. It is concluded that diffusion is the restricted step in Al2O3 dissolution into molten CaO-Al2O3-Fe2O3 slag; the chemical composition of the initial melts exerts a great influence on the activation energy for Al2O3 dissolution; the range of Al2O3 diffusivity is about 1.86 × 10−7 to 2.45 × 10−6 cm2/s; no apparent intermediate layer between the Al2O3 rod and melt is observed.

Viscosity and viscosity estimation model of fully liquid slags in TiO2–Al2O3–CaO–SiO2 and TiO2–Al2O3–CaO–SiO2–MgO systems with high TiO2 concentration and low mass ratio of CaO to SiO2

The present paper focuses on the viscosity of high titanium containing slags in the process of titanomagnetite smelting by taking the TiO2–Al2O3–CaO–SiO2 quaternary system with TiO2 in the range from 23 to 43%, Al2O3 in the range from 3 to 12% and basicity (mass ratio of CaO/SiO2) in the range from 0·3 to 0·7 as the object. Experimental determinations of the viscosity were carried out in the temperature range from 1573 to 1873 K using the rotation cylinder method. The effects of TiO2, Al2O3, basicity and temperature on viscosity were studied. The experimental results indicated that the viscosity decreased with increasing TiO2 concentration and basicity, and increased with increasing Al2O3 concentration. Based on the experimental data of the TiO2–Al2O3–CaO–SiO2 quaternary system, a new viscosity model was proposed by modifying the Urbain model. The new model was applied successfully to predict the viscosity of TiO2–Al2O3–CaO–SiO2 and TiO2–Al2O3–CaO–SiO2–MgO systems in the fully liquid condition with high TiO2 concentration and low basicity over a wide range of composition and temperature using one set of model parameters.

Experimental Investigation of the Viscosities of High Titanium Containing Slags with Low Mass Ratio of CaO to SiO<sub>2</sub>

This present paper focuses on the viscosities of high titanium containing slags in the process of titanomagnetite smelting by taking the TiO2-Al2O3-CaO-SiO2 quaternary system as the object. Experimental determinations of the viscosities were carried out in the temperature range from 1573 to 1773K using the rotation cylinder method. The measurements were conducted in the composition range from 23 to 33 mass pct TiO2, 3 to 9 mass pct Al2O3, and 0.3 to 0.7 basicity (mass ratio of CaO to SiO2). The effects of TiO2, Al2O3, basicity, and temperature on viscosity were studied. The experimental results indicated that the viscosities decreased with increasing TiO2 content and basicity, and increased with increasing Al2O3 content, above the liquidus temperature. Based on the experimental data, the liquidus temperatures of the slags were evaluated using the second derivatives of the activation energies for viscous flow with respect to temperature.

Process Development of Low-Cost AgNi and AgFe Contact Materials with no Range of Solid Solubility

AgNi and AgFe are known as contact materials with high workability and low contact resistance for medium to weak current contacts. However, AgNi and AgFe contact materials are difficult to manufacture using conventional melting and casting procedure because they exhibit no range of solid solubility of Ni and Fe in Ag for all temperature range. The purpose of this research is to develop a process for low-cost AgNi and AgFe contact materials based on solidification process control. AgNi and AgFe contact materials were produced by rotation cylinder method (RCM). The hardness value of AgNi and AgFe contact materials by RCM were higher than that of AgNi and AgFe contact materials produced by conventional powder metallurgy and co-precipitation processes. The higher hardness values of contact materials produced by RCM may be attributed to the uniform distribution and small size of Ni and Fe particles in Ag matrix.

Hydrogenation and Degradation Behaviors of Mg-Ni Alloys

In this study, melting and casting of Mg-Ni alloys in ambient atmosphere for mass production, nickel content adjustment for enhancing hydrogen capacity and reducing alloy weight, and cyclic hydriding/dehydriding test for evaluation of degradation properties were investigated. Mg-Ni alloys were fabricated by Rotation-Cylinder Method (RCM) in ambient atmosphere. Hydriding/dehydriding reactions were repeated 350 times at 350°C to evaluate degradation property. SEM-EDS analysis revealed that the lamellar eutectic structure of Mg-Ni alloy consists of Mg-rich α-phase and β-Mg2Ni. It is supposed that the lamellar eutectic structure enhances hydrogenation properties of Mg-Ni alloys.

Novel rotation-cylinder method for the processing of binary alloys with no range of solid solubility

The Ag–Fe binary system is of commercial importance for providing electrical contact materials replacing cancerous Cd-bearing Ag-CdO. Until now, however, Ag–Fe contact materials can only be manufactured by powder metallurgy, simply because there is no range of solid solubility of Fe in Ag. The purpose of this study is to develop a cost-effective molten-metal process for the production Ag–Fe binary contact materials based on a rotation-cylinder method (RCM), in terms of replacing cancerous Ag-CdO as well as reducing material cost and process cost. The present study includes RCM for alloying Ag and Fe, subsequent extrusion and drawing procedures, manufacturing step for solid-type and clad-type electrical contacts and finally mechanical properties of them.

Hydrogenation and degradation of Mg–10 wt% Ni alloy after cyclic hydriding–dehydriding

Hydrogenation and degradation properties of Mg–10 wt% Ni hydrogen storage alloys were investigated by cyclic hydriding–dehydriding tests. Mg–10 wt% Ni alloy was synthesized by rotation-cylinder method (RCM) under 0.3% HFC-134a/air atmosphere and their hydrogenation and degradation properties were evaluated by pressure-composition-isotherm (PCI) measurement. Hydrogen storage capacities gradually increased following 160 hydriding–dehydriding cycles and thereafter started to decrease. Measured maximum hydrogen capacity of Mg–10 wt% Ni alloy is 6.97 wt% at 623 K. Hydriding and dehydriding plateau pressure were kept constant for whole cycles. Reversible hydrogen capacity started to descend after 280 hydriding–dehydriding cycles. The lamellar eutectic structure of Mg–Ni alloy consists of Mg-rich α -phase and β - Mg 2 Ni . It is assumed that the lamellar eutectic structure enhances hydrogenation properties.

Evaluation of Microstructure on SiC<sub>p</sub>/AZ91 Magnesium Composite Fabricated by Rotation-Cylinder Method

Eco-friendly development and on-going research strategy of Rotation-Cylinder Method (RCM) is given for SiCp/AZ91 Mg composites, identifying some of the key factors that need to be controlled and indicating subsequent casting processes. RCM produces U-shaped laminar melt surface with a Rankine vortex even at high rotation speed in an ambient atmosphere, which allows quick and efficient incorporation and homogeneous distribution of SiC particulates into molten Mg alloys. Therefore, sound SiCp/AZ91 Mg composites can be manufactured in conjunction with subsequent casting processes, such as investment casting and thixocasting. A transmission electron microscopy study showed that the interfacial reaction products consist of Mg2Si, MgO, Mg17Al12 and Al6Mn, which were analyzed using primitive cell volume and zero order Laue zone pattern and single convergent beam electron diffraction pattern containing higher order Laue zone ring from a nanosized region.

Hydrogenation Properties of Mg-TiNi Hydrogen Storage Composites Materials

Magnesium and Magnesium alloys have been studied as one of the good lightweight hydrogen storage materials, but the materials have strong difficulties in the fabrication process of mass production until now. The Rotation-Cylinder Method (RCM) has been developed to fabricate magnesium-based composites with moderate rotation under normal atmosphere. Inthis study, the Mg-TiNi hydrogen storage composites materials were manufactured by RCM and evaluated their hydrogenation properties by a Sieverts-type automatic pressure-composition-isotherm (PCI) apparatus at 523, 573 and 623K. The hydrogenation properties of Mg-TiNi composites depended on the behavior of TiNi reinforcements. The formation of Mg hydride, MgH2, on 4h milling samples of Mg-10mass% TiNi intermetallics hinted to the catalytic behavior of TiNi reinforcements. In addition, the dehydriding profile at 573K revealed the two steps of plateau pressure, which were affected by the existence of multi hydride phases.

Electrical and Electrochemical Properties of Poly(P-Phenylene)-Based Carbon for Lithium Rechargeable Batteries

Magnesium and Magnesium alloys have been studied as one of the good lightweight hydrogen storage materials, but the materials have strong difficulties in the fabrication process of mass production until now. The Rotation-Cylinder Method (RCM) has been developed to fabricate magnesium-based composites with moderate rotation under normal atmosphere. In this study, the Mg-TiNi hydrogen storage composites materials were manufactured by RCM and evaluated their hydrogenation properties by a Sieverts-type automatic pressure-composition-isotherm (PCI) apparatus at 523, 573 and 623K. The hydrogenation properties of Mg-TiNi composites depended on the behavior of TiNi reinforcements. The formation of Mg hydride, MgH2, on 4h milling samples of Mg-10mass% TiNi intermetallics hinted to the catalytic behavior of TiNi reinforcements. In addition, the dehydriding profile at 573K revealed the two steps of plateau pressure, which were affected by the existence of multi hydride phases.

Hydriding/Dehydriding Behavior of Mg-Ni Systems

To fabricate high efficiency, light-weight hydrogen storage materials in an economical way, a hydrogen induced mechanical alloying (HIMA) and an advanced melting/casting process were employed in a Mg-Ni hydride alloy system. The hydrogenation properties of the synthesized or/and cast specimen were evaluated with an automatic PCI (pressure-composition-isotherm) apparatus and TGA (thermo-gravimetric analysis). To produce Mg2NiHx intermetallics in an economical way, especially, Mg and Ni chips were mechanically alloyed under 2 MPa of hydrogen atmosphere by planetary ball milling. Adopting 66:1 BCR (ball to chips mass ratio) for HIMA process, fully hydrogenated alloys were obtained after 96 hrs of milling, resulting intotal hydrogen content of 2.25 mass%. The dehydriding temperature was found to be 453∼493 K. The composite phase obtained after 96 hrs of HIMA appeared to be composed of nanocrystalline and amorphous phases, of which structure was believed to enhance hydriding and dehydriding kinetics. The condition of BCR seemed to affect strongly the synthesis of the Mg2NiHx. In addition, the minimized Ni content specimens in Mg-Ni hydrides were successfully manufactured by Rotation- Cylinder method (RCM) without any heat treatments.

Effect of Aluminum on the Corrosion Characteristics of Mg-4Ni-xAl Alloys

Abstract Corrosion properties of Mg-4Ni-xAl alloys were investigated using electrochemical techniques, pH measurement, hydrogen evolution test in acid-chloride solution (pH 5.4, 200 ppm Cl−), and surface analysis. The Mg-4Ni-xAl alloys were prepared by a new alloying method called rotation-cylinder method (RCM). Mg dissolution was closely related to the pH value of the test solution. At pH > 11, the surface of Mg alloys was covered by magnesium hydroxide (Mg[OH]2) film, which influenced the corrosion potential and corrosion rate of Mg alloys. In this case, the corrosion potential was shifted toward the anodic side and corrosion rate decreased. At pH < 11, however, corrosion rate continuously increased as a function of time. With increasing Al content in the Mg-4Ni-xAl alloys from 0 to 2 wt%, (1) the corrosion potential had more active potential, but the corrosion rate decreased, and (2) the segregation of the α-Mg/Mg2Ni eutectic phases at the grain boundary was reduced. Generally, Mg2Ni had more noble pot...

Effect of dual size particle distribution on processing and properties of AZ91D/SiCp magnesium matrix composites prepared by rotation cylinder method

Spiral fluidity and hardness and wear experiments were carried out to investigate the effect of dual size (5 and 50 μ m) SiC particle distributions on the fluidity, hardness, and wear resistance of Mg - 9.1Al - 0.7Zn (wt-%) alloy containing 10 vol.-% SiC particles, with the aim of tailoring properties to specific applications. Although a decrease in the fluidity of the composites is observed, as expected, in the presence of SiC particles, the fluidity of the composites with dual size particle distributions was in some instances better than that of composites containing the same volume fraction of single size particles. The hardness and wear resistance of the composites with dual size distributions were weakly dependent on the mixing ratio. In terms of complete molten processing and tailored mechanical properties, the optimum mixing ratio of 5 and 50 μm particles appears to be 1:2.

Evaluation of Hydrogenation Properties of Thixotropic Mg-3,6wt%Ni Hydrogen Absorbing Alloys

Magnesium-3, 6wt% Nickel alloys were fabricated by Rotation-Cylinder Method(RCM) in ambient atmosphere. The alloys were divided into two different heat-treating conditions, as-cast and thixotropic treated. Thixotropic heat treatment enhances the separation of primary hydride former of Mg and the catalytic phase of <TEX>$Mg_2$</TEX>Ni. Hydrogenation properties of the each alloy were evaluated and compared by PCI(Pressure-Composition Isotherm) measurement. The maximum hydrogen capacity and the reversible capacity of as -cast Mg-6wt% Ni alloy were 5.2wt% and 3.8wt% at 623k, respectively.

Fabrication of Mg−Ni hydrogen storage alloys by rotation-cylinder method

For many years, the Mg−Ni alloys have been studied as good lightweight hydrogen storage materials, however, the alloys present strong difficulties in the fabrication process of mass products. The rotation-cylinder method (RCM) has been developed for magnesium based composites with moderate rotation under a normal atmosphere. In this study, the Mg-3, 6, 9, 12 mass% Ni alloys were easily manufactured by RCM and their hydrogenation properties were evaluated with a Sieverts-type automatic pressure-composition-isotherm (PCI) apparatus at 523, 573 and 623K. The evolution of the microstructure of as-cast specimens appeared to be a typical hypoeutectic structure. From the results of the backscattered electron image (BEI) and energy dispersive spectrometry (EDS), the difference between the composition of the α-Mg and Ni-rich eutectic regions was distinguished clearly. The hydrogenation properties of Mg−Ni alloys depended on the behavior of the nickel compositions. Especially, the hydrogen kinetics of Mg-9 mass% Ni was more excellent than the others.

An experimental study of the viscosities of Al2O3-CaO-“FeO” slags

Experimental determinations of the viscosities of some Al2O3-CaO-“FeO” ternary slags were carried out in the temperature range from 1550 to 1764 K using the rotation cylinder method. The measurements were conducted in the composition range from 36 to 48 mass pct Al2O3, 28 to 42 mass pct CaO, and 10 to 33 mass pct FeO. The viscosity was found to show a decreasing trend with the increase of FeO content. Based on the experimental data, the liquidus temperatures of the slags were evaluated using the second derivatives of the activation energies for viscous flow with respect to temperature. The evaluated liquids temperatures were compared with the results of differential thermal analysis (DTA) on the same slag samples.

Microstructural Evolution and Thixoformability of Semisolid SiCp/AZ91D Mg Composites

Rotation-Cylinder method (RCM) as a primary manufacturing process and thixoforming as a secondary forming process are discussed. RCM allows the production of U-shaped laminar melt surface with Rankine vortex, thus significantly reducing particle agglomeration and entrapped slags. Thixoforming is of particular interest as a secondary forming process because of the low fluidity of the composites and the significant wear produced on machining tools and extrusion and forging dies. Some indications about mechanical properties of the composites are also presented.

Microstructure of Partially Remelted Thixoformable Mg-Ni Alloys

The aim of this paper is to develop a thixoformable model alloy, Mg–Ni alloy of binary eutectic system with no range of solid solubility and to report the experimental results concerning the microstructural evolution of the alloys in the reheated semisolid state. Mg–Ni alloys of various nickel compositions were produced in the form of cylindrical billets by Rotation-Cylinder method. The results showed that the appropriate thixotropic structure, the globular solid phase with less liquid droplets entrapped inside the solid, could be obtained by the normal solidification and simple reheating procedures. Of more important feature of the thixoformable Mg–Ni alloy is that the size of the solid globules and the fraction liquid were mainly dependent on nickel composition, therefore could be controllable.

Rotation-cylinder method for fabrication of SiC particle reinforced magnesium composites

A new molten metal mixing process, RCM (Rotation-Cylinder Method) for incorporating reinforcement particles into molten magnesium, has been developed for manufacturing SiC particle reinforced magnesium composites in an ambient atmosphere. The RCM can be characterized by the U-shaped laminar melt surface with the Rankine vortex, which significantly reduces particle agglomeration and entrapped slags, such that composites of improved microstructure and properties can be manufactured successfully in conjunction with the subsequent fabrication processes. The RCM can incorporate SiC particles (5 urn size and larger) into molten magnesium with particle volume fractions of up to 20 vol.%. In this paper, the development background, the characteristic vortical motions, the optimum manufacturing conditions and the in-process wetting procedures of the RCM are described.