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The crystallography of the Ca2SiO4-Ca3P2O8 solid solutions in the dephosphorization slag in current steelmaking process was determined in this study. Understanding the physical and chemical properties of these Ca2SiO4-Ca3P2O8 solid solutions is a preliminary step towards understanding the role of the Ca2SiO4-Ca3P2O8 solid solutions in the dephosphorization process. The range of Ca3P2O8 in the Ca2SiO4-Ca3P2O8 solid solutions synthesized for analysis varied from 10 to 90 mol pct, with an incremental increase of 10 mol pct per solid solution. In solid solutions with a Ca3P2O8 content of up to 40 mol pct, the crystal structure at 1773 K was found to be hexagonal, while the solid solutions with a Ca3P2O8 content over 70 mol pct had a trigonal structure. The silicocarnotite solid solutions observed when the Ca3P2O8 content was 50 to 60 mol pct were likely formed by phase transformation during cooling. In the stable solid solution with a Ca3P2O8 content of 50 to 60 mol pct at 1773 K before the occurrence of transformation, the crystal structure is trigonal since it is in the Ca3P2O8-rich range. A linear increase in the lattice parameters c of the solid solutions in the range of (0, 40 mol pct) and (70 mol pct, 100 mol pct) was found with increasing Ca3P2O8 content. The lattice parameter a, however, was almost independent of the Ca3P2O8 content in the solid solutions.

A high-purity zeolite 4A was synthesized by the hydrothermal method using fly ash as the raw material. The effects of sodium hydroxide (NaOH) or/and sodium carbonate (Na2CO3) on the activation of fly ash were studied, and the removal efficiency of Cu2+ in aqueous solution was also investigated for the synthesized zeolite. The formation process of the zeolite from fly ash was surveyed by ex situ techniques such as X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TG-DCS), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX) and Fourier transform infrared spectroscopy (FTIR). The important influential factors of energy and water consumption were analysed by orthogonal tests, and the best conditions for green synthesis were accurately determined through batch tests. The factors affecting the green synthesis of zeolite are the alkali mixture ratio, alkali melting temperatures, solid-to-liquid ratios, crystallization times and crystallization temperatures. The alkali mixture ratio was indicated to be an important factor for green synthesis according to the results of the orthogonal test. Compared with the use of alkali alone, when NaOH and Na2CO3 were mixed at a mass ratio of 1:2.8, the alkali melting temperature (760 °C) and solid-to-liquid ratios (1:5) were both lower, the crystallization time (4 h) was shorter in the zeolite synthesis process, and the relative crystallinity was the highest at 75.8%. The removal rate of 100 mg/L Cu2+ solution from pH 3 to pH 7 by 0.18 g of zeolite synthesized for 60 min was close to 100%, and the adsorption capacity was 55.5 mg/g. After the zeolite was desorbed and reused 4 times, the removal efficiency of Cu2+ was maintained at 73% at a pH of 3.

Because high-purity silicon is one of the core materials for use in cleaner energy industry, silicon purification techniques have taken on greater importance. An understanding of the thermodynamics of impurity elements in silicon is therefore of great scientific and industrial importance. Experimental and assessment works on the thermodynamics of 23 impurity elements (Ag, Al, Au, B, Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Ni, P, Pb, Sb, Ta, Ti, V, W, Zn, and Zr) in silicon melts are reviewed herein, and their activity coefficients in dilute silicon melts are discussed. The parameters suggested for use in assessing the liquid phase in each of the silicon binary systems are selected based on this discussion. The segregation coefficients of impurity elements calculated using the activity coefficients agree well with reported values and are used to evaluate silicon purification by directional solidification. The purpose of this paper is to provide fundamental and systemic thermodynamics knowledge for the development of silicon purification processes.

The physicochemical properties of the Ni-Co-Fe-O system are important to the high-temperature oxidation of the Ni-Co-Fe based alloy, such as superalloys and high-alloy steels. The equilibrium phase relations between the Ni-Co-Fe alloy and its oxide at elevated temperature were systematically investigated using experimental and assessment method. The iso- p O 2 lines and iso-concentration lines of oxides in the entire range of the oxygen partial pressure and composition at 1673 K were evaluated, and the high-temperature oxidation path of the Ni-Co-Fe alloy was qualitatively examined. Using the thermodynamic findings allows to ascertain the high-temperature oxidation phenomena of the Ni-Co-Fe based alloy.

In this study, the elemental distribution of 26 elements in a ferronickel electric furnace was thermodynamically analyzed to determine the removability of impurities from secondary resources during smelting. Phosphorus was evaluated both thermodynamically and experimentally. It was found that Al, B, Ca, Ce, Cr, La, Mg, Mn, Nb, Si, Sr, Ta, Ti, U, V, and Zr were removed in slag phase, while Ag, Pb, and Zn were removed in gas phase. W and Mo could be removed in slag phase by increasing oxygen partial pressure. P was partially removed in a ferronickel slag that contained MgO. Most of the P was removed by the addition of CaO to the slag. In a case study, the recycling of secondary resources containing a large amount of P was found to be possible by the addition of CaO to the slag and by the adjustment of additive amount of secondary resources to the ferronickel ore.

A CMOS on-chip oscillator for the local interconnection network bus is presented. The temperature dependence of the output frequency is compensated by the voltage ratio adjusting technique. The frequency variation with supply voltage is reduced by a voltage regulator with a wide input range of 1.8–5 V. The frequency shift caused by package stress is minimized by resistor placement. Over a temperature range of −40 °C to 150 °C, the measured temperature coefficients of the output frequency are 3.2 ppm/°C without the effect of the package stress and 14.2 ppm/°C with the effect of the package stress, respectively. The measured frequency variation with supply voltage is within ±0.015%.

To design optimal pyrometallurgical processes for nickel and cobalt recycling, and more particularly for the end-of-life process of Ni–Co–Fe-based end-of-life (EoL) superalloys, knowledge of their activity coefficients in slags is essential. In this study, the activity coefficients of NiO and CoO in CaO–Al2O3–SiO2 slag, a candidate slag used for the EoL superalloy remelting process, were measured using gas/slag/metal equilibrium experiments. These activity coefficients were then used to consider the recycling efficiency of nickel and cobalt by remelting EoL superalloys using CaO–Al2O3–SiO2 slag. The activity coefficients of NiO and CoO in CaO–Al2O3–SiO2 slag both show a positive deviation from Raoult’s law, with values that vary from 1 to 5 depending on the change in basicity. The activity coefficients of NiO and CoO peak in the slag with a composition near B = (%CaO)/(%SiO2) = 1, where B is the basicity. We observed that controlling the slag composition at approximately B = 1 effectively reduces the cobalt and nickel oxidation losses and promotes the oxidation removal of iron during the remelting process of EoL superalloys.

The collected end-of-life (EoL) silicon wafers from the discharged photovoltaic (PV) panels are easily contaminated by impurities such as doping elements and attached materials. In this study, the thermodynamic criteria for EoL silicon wafers refining using three most typical metallurgical refining processes: oxidation refining, evaporation refining, and solvent refining were systemically and quantitatively evaluated. A total of 42 elements (Ag, Al, Au, B, Be, Bi, C, Ca, Ce, Co, Cr, Cu, Fe, Ga, Gd, Ge, Hf, In, La, Mg, Mn, Mo, Na, Nb, Ni, Os, P, Pb, Pd, Pt, Re, Ru, Sb, Sn, Ta, Ti, U, V, W, Y, Zn, Zr) that are likely to be contained in the collected EoL silicon-based PV panels were considered. The principal findings are that the removal of aluminum, beryllium, boron, calcium, gadolinium, hafnium, uranium, yttrium, and zirconium into the slag, and removal of antimony, bismuth, carbon, lead, magnesium, phosphorus, silver, sodium, and zinc into vapor phase is possible. Further, solvent refining process using aluminum, copper, and zinc as the solvent metals, among the considered 14 potential ones, was found to be efficient for the EoL silicon wafers refining. Particularly, purification of the phosphorus doped n-type PV panels using solvent metal zinc and purification of the boron doped p-type PV panels using solvent metal aluminum are preferable. The efficiency of metallurgical processes for separating most of the impurity elements was demonstrated, and to promote the recycling efficiency, a comprehensive management and recycling system considering the metallurgical criteria of EoL silicon wafers refining is critical., Graphical Abstract

In ironmaking, maintaining gas permeability in blast furnace with low coke rate operation is essential to reduce carbon emissions. The high pressure loss in the cohesive zone decreases the gas permeability and affects the productivity of blast furnace. In order to increase the gas permeability in the cohesive zone, the thickness of the cohesive layer should be decreased. For this purpose, increasing softening temperature and decreasing dripping temperature of the iron ore are desired. In this study, softening, melting, and permeation of SiO2-FeO-CaO-Al2O3-MgO on a coke bed were investigated. The oxide sample in a tablet form was heated under CO/CO2 atmosphere, and the shape of the tablet was observed. The softening and melting temperatures of the SiO2-FeO-CaO system changed with the addition of Al2O3 and MgO. Oxide tablets with and without Al2O3 softened below and above the solidus temperature, respectively. The melting temperatures varied with the ratio of CO/CO2 in the gas. The permeation temperature was independent of the melting temperature, but dependent on the wettability.

The recoverability of phosphorus oxide from steelmaking slag was investigated using a mechanical approach involving capillary action. It was found that P2O5 was concentrated in the 2CaO·SiO2 phase. To separate the P2O5-enriched solid 2CaO·SiO2 phase and FeO-rich liquid phase in steelmaking slag, capillary action was used to facilitate penetration into absorbers such as sintered CaO, Fe2O3, and CaCO3 tablet. Once the liquid phase had penetrated the absorber, it was found that the solid 2CaO·SiO2 phase and FeO-rich phase could be effectively separated. When CaCO3 was used as an absorber, 91 % of phosphorus oxide in the steelmaking slag was recovered in solid 2CaO·SiO2 phase. The recovered absorber, which includes a FeO-rich liquid phase, may be used as Fe source, and the 2CaO·SiO2 phase, which includes P2O5, may be used as P source.

Iron (Fe) is a metal element which is most abundantly produced in the world. Steel is an alloy of iron and other elements and plays a crucial role in the development of sustainable society. In the iron manufacturing process, the content of phosphorus (P) in the raw materials is relatively low but is concentrated into molten iron and then removed nearly completely into steelmaking slag. Hence, steelmaking can be viewed as a P enrichment process and generates slag which has a potential to serve as a secondary resource of P. The fundamental system of steelmaking slag is CaO-FeO-SiO2 which is formed inside the primary 2CaO・SiO2 region, indicating that this phase precipitates at the early stage of cooling slag. P is unevenly distributed in steelmaking slag and generally concentrated in the 2CaO・SiO2 phase as a 2CaO・SiO2-3CaO・P2O5 solid solution. This evidence reveals the potential to separate P from steelmaking slag. In this chapter, various technologies for P separation and recovery from steelmaking slag are described. They include magnetic separation, capillary action, dissolution, and carbothermic reduction. Since each method has its own merits and demerits, the best choice of single or combination of the technology options is critical to effective P recovery and separation from steelmaking slag.

Optical frequency combs (OFCs) generated by an InP-based semiconductor Mach-Zehnder modulator (MZM) are numerically investigated. Nonlinear phase modulation induced by drive voltages applied to the MZM prove to be useful in obtaining a flat OFC. The experimentally measured intensity deviations of OFCs reported previously are quantitatively reproduced using a numerical model considering nonlinear change of refractive index and optical absorption induced by the drive voltages applied to the MZM. It is found that such nonlinearities generate a flat nine-channel (9-ch) OFC with an intensity deviation of

The removability of impurities during the aluminum remelting process by oxidation was previously investigated by our research group. In the present work, alternative impurity removal with chlorination has been evaluated by thermodynamic analysis. For 43 different elements, equilibrium distribution ratios among metal, chloride flux and oxide slag phases in the aluminum remelting process were calculated by assuming the binary systems of aluminum and an impurity element. It was found that the removability of impurities isn’t significantly affected by process parameters such as chloride partial pressure, temperature and flux composition. It was shown that Ho, Dy, Li, La, Mg, Gd, Ce, Yb, Ca and Sr can be potentially eliminated into flux by chlorination from the remelted aluminum. Chlorination and oxidation are not effective to remove other impurities from the melting aluminum, due to the limited parameters which can be controlled during the remelting process. It follows that a proper management of aluminum scrap such as sorting based on the composition of the products is important for sustainable aluminum recycling.

Slag as by-product of Cu making has been produced in large amounts in Chile, and around 5 million tons of slag are estimated to be disposed every year and 40 to 45 million tons have been accumulated. Typical Chilean Cu slag contains about 0.3 mass% Mo which is the grade of primary mine production of molybdenite and it also contains about 40 mass% of Fe and 1 mass% Cu. Recovery of Mo from Chilean copper slag is quite attractive to secure a stable Mo supply. The feasibility of the recovery of Mo from Cu slag as Fe-Mo alloys by carbon reduction is investigated in the present work. Mo in Cu slag is found to be fully recovered as Fe rich alloy. The recovered Fe rich alloy contains about 0.65mass% Mo and 2.4 mass% Cu. In addition, to use the recovered Fe-Mo alloy in the special steel industry, which is the most important market for molybdenum, Cu in the produced Fe-Mo alloy is successfully decreased from 2.4 mass% to 0.1 mass% by using FeS-Na2S flux. Thus, Mo recovery from Chilean Cu slag can be promising.

Suppression of CO2 discharged from iron- and steel- making companies is an example of the biggest issues for the protection of global environment and sustainable growth of steelmaking industry. One of the efforts made to decrease the emission of CO2 in ironmaking process is blowing of hydrogen gas into blast furnace. Hydrogen gas can reduce iron oxide and form harmless H2O. Cementite (Fe3C) may be formed by introduction of hydrogen into blast furnace and play an important role on carburization and smelting behavior of reduced iron. The conditions that Fe3C was formed were experimentally determined by changing CO–CO2–H2 gas composition in the present work. As the result, it was found that there is a possibility of Fe3C formation by hydrogen gas introduction into blast furnace. Therefore, the effect of Fe3C on smelting behavior of reduced iron was also observed, and it was confirmed that the presence of Fe3C will have positive effect on enhancing carburization and smelting of reduced iron.

The Ti deoxidation equilibrium of Fe–Ni, Fe–Cr and Fe–Cr–Ni alloys saturated with ‘Ti3O5’ and Ti2O3 phase was clarified in previous researches. Solubility of Fe, Cr and/or Ni oxides in ‘Ti3O5’ phase equilibrated with liquid Fe–Ni, Fe–Cr and Fe–Cr–Ni alloys at 1823 K to 1923 K were measured by SEM–EDS. It was confirmed that the solubility of Fe, Cr and/or Ni oxide in ‘Ti3O5’ phase at low Ti content increase with decrease of Ti content in alloys. Titanium content that dissolution of Fe, Cr and/or Ni oxide into ‘Ti3O5’ phase becomes apparent increases with increase of Cr and/or Ni content of the alloys. The activity of Ti deoxidation product, ‘Ti3O5’ phase, equilibrated with Fe–Ni, Fe–Cr and Fe–Cr–Ni alloys was also evaluated by Redlich-Kister type polynomial. Equilibrium between Ti and O at low Ti content of those alloys was analyzed using the activity of ‘Ti3O5’ phase.

The most important subject in the steelmaking process is the control of non-metallic inclusions. Non-metallic inclusions with a high melting point do not deform during a hot working process because they are relatively hard. Hence, the inclusion composition should be controlled in order to achieve a low melting point to prevent product defects. Therefore, an MnO–SiO2-based inclusion is considered to be one of the preferred systems. Moreover, the heat treatment of austenitic stainless steel has been reported to influence the composition of MnO–SiO2-type inclusions; these inclusions change into MnO–Cr2O3-type, MnO–Nb2O5-type, and MnO–V2O3-type inclusions. In this study, we investigated the influence of heat treatment on the composition of the inclusions in the martensitic stainless steel. In general, a scanning electron microscope–energy dispersive x-ray spectrometer (SEM–EDS) is used for the quantitative analysis of inclusions; however, SEM–EDS cannot simultaneously analyze a large number of inclusions. Therefore, a new technique using the SEM–EDS along with the image analysis software “Particle Analysis” was used for the chemical analysis and the size measurement of a large number of inclusions (hereafter abbreviated as the PA method). The heat-treatment-induced compositional change of the inclusions in martensitic stainless steel was evaluated by using both the analysis methods.

Utilization of steelmaking slag is indispensable for sustainable growth of steelmaking industry. Steelmaking slag contains nutrition such as phosphorus, silicon and iron and may be utilized as a fertilizer if elution of environmentally regulated elements is negligible. Chromium is contained in stainless steel slag as an oxide and stabilization of this chromium oxide in the slag is very important in the view of environmental protection.Elution behavior of elements from chromium containing phases into seawater was investigated to observe the stability of phases that may exist in steelmaking slag. It was found that the existence of 2CaO·SiO2 enhanced the dissolution of chromium into seawater. Elution behavior of chromium from especially synthesized stainless steel slag into seawater was investigated. Finally, fixation of chromium was conducted by control of mineralogical phase with SiO2 addition to stainless steel slag. Addition of SiO2 to the slag was very effective for prevention of chromium elution into seawater.

Suppression of CO2 discharged from iron and steelmaking companies is an example of the biggest issues for the protection of global environment and sustainable growth of steelmaking industry. One of the efforts made to decrease the emission of CO2 in ironmaking process is blowing of hydrogen gas into blast furnace. Hydrogen gas can reduce iron oxide and form harmless H2O. Cementite (Fe3C) may be formed by introduction of hydrogen into blast furnace and play an important role on carburization and smelting behavior of reduced iron. In the present work, Fe3C sample was held at 800–1 100 K under Ar atmosphere to clarify the stability and the behavior of Fe3C phase. It was confirmed that metastable Fe3C phase will decompose under Ar atmosphere at 800 K and rapidly decompose at temperature over 900 K. Also, it was found that composite of nano-size C and Fe will form when Fe3C decompose.

Currently, several metals are commercially recycled from by-products and wastes by metallurgical processing. However, the metallurgical process has each characteristic, which causes limitation for resource recovery. The combinations of elements in secondary resources, such as by-products and wastes, are often different from those in natural resources. There are even combinations that are not present in natural resources. Conventional metallurgical processes have been optimized for economical and efficient extraction of desired elements only from large amount of ores under constant grade. Therefore, in order to extract metals from secondary resources by the conventional metallurgical process, it is necessary to estimate the recoverability of the constituent elements by taking into account their chemical properties well in advance. In particular, analysis for combination of elements is significantly important. In this study, we developed the evaluation method of metal resources recoverability based on thermodynamic analysis, and made clear the element distribution among gas, slag and metal phases during metal recovery based on thermodynamic analysis. In an application of the method shows that Cu, and precious metals (Ag, Au, Pt, Pd) present in mobile phones can be recovered as metals in the pyrometallurgy process of Cu in a converter. Other elements distributed in the slag phase are difficult to recover. The result of our analysis reflects the trends observed in the distribution of metals in copper metallurgy, thereby indicating the validity of our proposed evaluation method.

Currently, several metals are commercially recycled from by-products and wastes by metallurgical processing. However, the metallurgical process has each characteristic, which causes limitation for resource recovery. The combinations of elements in secondary resources, such as by-products and wastes, are often different from those in natural resources. There are even combinations that are not present in natural resources. Conventional metallurgical processes have been optimized for economical and efficient extraction of desired elements only from large amount of ores under constant grade. Therefore, in order to extract metals from secondary resources by the conventional metallurgical process, it is necessary to estimate the recoverability of the constituent elements by taking into account their chemical properties well in advance. In particular, analysis for combination of elements is significantly important. In this study, we developed the evaluation method of metal resources recyclability based on thermodynamic analysis, and made clear the element distribution among gas, slag and metal phases during metal recovery based on thermodynamic analysis. In an application of the method shows that Cu, and precious metals (Ag, Au, Pt, Pd) present in mobile phones can be recovered as metals in the pyrometallurgy process of Cu in a converter, while Pb and Zn can be recovered as vapor. Other elements distributed in the slag phase are difficult to recover. The result of our analysis reflects the trends observed in the distribution of metals in copper metallurgy, thereby indicating the validity of our proposed evaluation method.

Equilibrium relation between Ti and O in molten Fe–Ni alloy has been investigated at 1873 to 1923 K. Ti oxide equilibrated with molten Fe–Ni alloy has been determined by EBSD (Electron Backscatter Diffraction) pattern analysis using FE-SEM (Field Emission Scanning Electron Microscope). The present results have been numerically analyzed by the excess Gibbs free energy change of mixing for the Fe–Ni–Ti–O system with Redlich–Kister type polynomial. Redlich–Kister type polynomial parameters concerning Ni and Ti were determined as follows,0ΩNi–Ti = 424280−270.40T J/mol (XTi

Titanium deoxidation equilibria between Ti and O in molten Fe–Cr and Fe–Cr–Ni alloys were investigated at temperatures of 1823 to 1923 K. Titanium oxides equilibrated with molten Fe–Cr and Fe–Cr–Ni alloys have been determined by EBSD (Electron Backscatter Diffraction) pattern analysis using FE-SEM (Field Emission Scanning Electron Microscope). Deoxidation product changes from Ti2O3 to Ti3O5 with decrease of Ti content in Fe–Cr and Fe–Cr–Ni alloys.Binary interaction parameters of Redlich–Kister type polynomial between Cr and O was assessed by using the previous experimental result in the Fe–Cr–O system. Experimental result of titanium deoxidation in molten Fe–Cr alloy has been numerically analyzed by the excess Gibbs free energy change of mixing Fe–Cr–Ti–O system with Redlich–Kister type polynomial. Validity of evaluated parameters between Cr–O (ΩCr–O) and Cr–Ti (ΩCr–Ti) was confirmed by comparison with experimental result for Fe–Cr–Ni alloy.Binary interaction parameters of Redlich–Kister type polynomial in present work were evaluated as follows,0ΩCr–O = −52870−24.10T J/mol (XO

Iron nugget making process by rapid heating reduction of powdery iron ore and pulverized coal mixture is regarded as one of the novel iron-making processes. Iron carburization during smelting reduction is especially important reaction step from the viewpoint of saving energy in this process. If the rate and efficiency of carburization reaction are increased, energy consumption of the process will be reduced to large extent. The purpose of this study is to clarify the carburization degree of iron nugget during smelting reduction of the mixture.The sample was prepared from graphite, electrolytic iron powder and synthetic slag containing iron oxide to simulate iron carburization phenomena during smelting reduction of the mixture in the present work. The sample was quenched immediately after the mixture changed into nugget shape in a rapid heating process. Laser microscope combined with infrared image furnace was used for sample heating and observation of carburization phenomena, and carbon content in the nugget was chemically analyzed after quenching.From above-mentioned investigations, it was revealed that the occurrence of carburization during smelting reduction in the sample mixture is advantageous to obtain higher carbon contain iron nugget.

Aluminum deoxidation equilibrium of molten Fe–Ni alloy was determined by chemical equilibrium method at temperature of 1873 to 1973 K. Also, critical point in molten Fe–40mass%Ni alloy that coexisted with Al2O3 and FeO·Al2O3 was determined experimentally at 1973 K. Solvent extraction method was applied to improve the analytical accuracy of the low aluminum content in molten Fe–Ni alloy. The relation between aluminum and oxygen contents in molten Fe–Ni alloy equilibrated with Al2O3 or FeO·Al2O3 was estimated in the whole alloy composition range at 1873 to 1973 K by utilizing the metallic solution model based on Darken's quadratic formalism and Redlich–Kister type polynomial.

To investigate the slag permeation to packed bed of carbonaceous materials, the measurement of molten slag's densities, surface tensions and dynamic contact angle on carbonaceous materials at relatively low temperatures (from 1 673 to 1 773 K) are carried out by applying the sessile droplet method. The interfacial compositions of slags and carbonaceous materials were examined by SEM/EDX. SiC at carbonaceous material surface was not observed. The variation of measured density, contact angle and surface tension with time were found to be almost negligible with given slag composition and at given temperature. It is reported that carbonaceous material wettability at the temperature of more than 1 873 K was strongly dependent on the slag composition as well as carbon properties. The almost constant contact angel with time in this study can be attributed to the negligible formation of SiC at carbonaceous material surface. The slag permeation model has been developed along with the measurement of physical properties. The maximum retention height of liquid layer on the sphere packing layer is expressed by H c =A/L c +L c /2, where A is constant and H c and L c are the dimensionless slag layer retention height and the dimensionless sphere's diameter, respectively. Slag layer retention height on the carbonaceous material packing layer is evaluated using the measured physical properties. The proposed characteristic length λ(=√ -γL cosθ/pg) in the model can be used to characterize the slag permeation behaviour.

There are huge quantities of uncertainties on the Ti deoxdiation equilibrium constants and their interaction parameters in the literatures including the recommended values by the Japan Society for the Promotion of Science (JSPS). The main reason of such uncertainties among the previous works is due to the insufficient information of titanium oxide phase in equilibrium with liquid Fe–Ti alloy. The measurement of the equilibrium phase changes of titanium oxides with various Ti contents in molten Fe–Ti alloy has been carried out in the present study. Molten Fe–Ti alloys with various Ti contents have been equilibrated with ‘Ti3O5’ crucibles at 1 873 K. The kinds of Ti oxide at the interface of ‘Ti3O5’ crucible contacted with molten Fe–Ti alloys have been identified as the equilibrium titanium oxides with the electron backscatter diffraction (EBSD) pattern analysis technique. After the ‘Ti3O5’ crucible reacted with molten Fe–Ti alloys adequately and both of them were quenched.The present result on the stable region of equilibrium titanium oxides with Ti contents in Fe–Ti alloy was in good agreement with the thermodynamically calculated results based on the free energies of titanium oxides formation and the activity of Ti in Fe–Ti alloy.

We propose a new electrostatically-actuated micromirror array. Using solder flip chip bonding technology, the desired electrode gap and the mirror rotation range can be easily created and enlarged. The use of solder assembly technology also provides us not only design flexibility but also precise gap height and mirror position control. In the mirror assembly process, a new MEMS transfer method using temporary fuse-away tethers is used to achieve robust and clean batch assembly. The mirror array is designed through FEM analysis and design optimization using a surface response method. The driving power of the optimized mirror system is reduced to one-third that of the initial design. The testing results of the fabricated mirror device show consistency with the predicted mirror performance and assembly precision.

Numerical analysis on Si deoxidation of molten Fe, Ni, Fe-Ni, Fe-Cr, Fe-Cr-Ni, Ni-Cu and Ni-Co alloys have been carried out. The excess Gibbs free energy change of mixing has described with Redlich-Kister type polynomial using the relation derived from Darken's quadratic formalism. Excellent agreement between present work and experimental results was found for equilibrium Si and O contents in molten Fe, Ni, Fe-Ni, Fe-Cr, Fe-Cr-Ni, Ni-Cu and Ni-Co alloys. Si deoxidation equilibrium of not only one component metal but also alloys can be analyzed numerically using the formula determined in the present work. Also, interaction parameters of Redlich-Kister type polynomial can be easily converted into interaction coefficients with Taylor's series, which are widely used in steelmaking processes.