Solubility of Li<Subscript>2</Subscript>O in an LiCl–KCl Melt

The phase diagrams of the binary LiCl–Li₂O system and the quasi-binary [LiCl–KCl]–Li₂O systems containing 10 and 20 mol % KCl have been built using thermal analysis of cooling curves and isothermal saturation curves. The solubility of Li₂O in LiCl–KCl melts is determined in the temperature range 500–800°C. The solubility of Li₂O in the melts LiCl, LiCl–KCl (10 mol %) and LiCl–KCl (20 mol %) decreases as the KCl content increases;at 650°C, it is 11.5, 7.7, and 3.9 mol %, respectively.     

Corrosion of 12Kh18N10T Steel in the LiCl–KCl–<Emphasis Type=Italic>n</Emphasis>NdCl<Subscript>3</Subscript> Melt

The high-temperature corrosion of a 12Kh18N10T steel in the melt of lithium and potassium chlorides and neodymium trichlorides is investigated at a temperature of 773 K. The NdCl₃ concentration is varied from 0.2 to 5 mol %. In this study, neodymium is an analog of uranium. The composition of the electrolyte is close to the composition of the electrolytes used for processing nitride spent nuclear fuel (SNF). The main investigation technique is gravimetry, which includes aging of the steel in the melt for 1–24 h. Atomic absorption and electron microprobe analyses are also used.     

Thermodynamic Modeling of Metal Desulfurization with Boron-Containing Slags of the CaO–SiO<Subscript>2</Subscript>–MgO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–B<Subscript>2</Subscript>O<Subscript>3</Subscript> System

In thermodynamic modeling of the desulfurization of steel by CaO–SiO₂–MgO–Al₂O₃–B₂O₃ slag on the basis of HSC 6.12 Chemistry software (Outokumpu), the influence of the temperature (1500–1700°C), the slag basicity (2–5), and the B₂O₃ content (1–4%)1 on the desulfurization is analyzed. It is found that the sulfur content is reduced with increase in the temperature from 1500 to 1700°C, within the given range of slag basicity. At 1600°C, the sulfur content in the metal is 0.0052% for slag of basicity 2; at 1650°C, by contrast, its content is 0.0048%. Increase in slag basicity from 2 to 5 improves the desulfurization, which increases from 80.7 to 98.7% at 1600°C. If the B₂O₃ content in the slag rises, desulfurization is impaired. At 1600°C, the sulfur content in the metal may be reduced to 0.0052 and 0.0098% when using slag of basicity 2 with 1 and 4% B₂O₃, respectively; in the same conditions but with slag of basicity 5, the corresponding values are 0.00036 and 0.00088%, respectively. Note that desulfurization is better for slag without B₂O₃. According to thermodynamic modeling, metal with 0.0039 and 0.00019% S is obtained at 1600°C when using slag of basicity 2 and 5, respectively, that contains no B₂O₃. The results obtained by thermodynamic modeling for the desulfurization of metal by CaO–SiO₂–MgO–Al₂O₃–B₂O₃ slag of basicity 2–5 in the range 1500–1700°C are consistent with experimental data and may be used in improving the desulfurization of steel by slag that contains boron.     

Investigation into the solubility of nanopowders of the ZrO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript>–CeO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> system in the aqueous medium at various pH

Nanopowders of ZrO₂–Y₂O₃–CeO₂ and ZrO₂–Y₂O₃–CeO₂–Al₂O₃ systems are investigated with the purpose of studying the influence of pH of the dispersed medium on the solubility of nanopowder particles of a complex composition in an aqueous medium after membrane filtration and centrifugation to further prepare the stable dispersions necessary for toxicological investigations of nanoparticles. Concentrations of elements remaining in a supernatant after the sample preparation, which includes membrane filtration and centrifugation, are measured by inductively coupled plasma optical emission spectroscopy. It is established that that the largest aggregative stability of the nanopowder dispersion without the Al₂O₃ additive corresponds to the optimal range of pH 5.5–9.5, while with the Al₂O₃ additive, it is region pH 7.0. The results evidence that, when dispersing these powders, the hydrosol of yttrium oxyhydroxide, which is dissolved at pH < 6.0, is formed. When dissolving in water of the powder with the Al₂O₃ additive in the neutral medium, aluminum hydroxide is formed; in the acidic medium (pH < 6), it is replaced by main soluble aluminum salts; and in the alkali medium (pH > 7), amphoteric aluminum hydroxide is dissolved because of the formation of aluminates.     

Multi-objective Optimization of Electrodeposition of Ni–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Nano Composite Coating on Al6061 Substrate

Response surface methodology based Grey relation analysis has been used to optimize the coating parameters of composite coating on aluminium based alloys. This approach gives the best combination of coating parameters to get maximum coating thickness, adhesive strength, microhardness, and minimum wear rate. For each response, the effect of coating parameters at different levels have been discussed. From Grey relation grade, the optimum parameters for better composite coating performance are found to be: temperature, 34 °C; current density, 1 A/dm²; and percentage of particle loading, 1.2 g/L. At 95% significance level, the Current density shows statistical significance on overall composite coating performance.     

Stabilization of the fluorite phase in the ZrO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript> system

The calculated and experimental vertical ZrO₂–Y₂O₃ sections of the Zr–Y–O system are compared to find the region of a stable fluorite structure of yttrium-stabilized zirconia (YSZ). X-ray diffraction (XRD) and Raman scattering are used to study the crystal and local structures of mixed oxide 0.82ZrO₂ · 0.18Y₂O₃ (18YSZ) powders prepared by isothermal annealing of a precursor precipitated from a salt solution. The formation of a fluorite-type fcc structure (space group \(Fm\overline 3 m\)) in the powders is detected by XRD. Raman scattering study of the local structure of the cubic 18YSZ powders revealed traces of the tetragonal phase in them.     

Ni–Fe–Mn–(nano)Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Coating with Modulated Composition and Grain Size

Composition modulated nanocomposite of Ni–Fe–Mn–Al₂O₃ coatings were fabricated on mild steel using single bath technique through alternative variation of duty cycle at constant frequency (VD) and repeated alteration of frequency at constant duty cycle (VF). The number of layers was 32 and thickness of each layer was 2.5 µm. The results of microstructure examination by SEM and EDS for VD coatings exhibited that Fe/Al₂O₃-rich layers adjacent to Mn rich ones were deposited in a frequent manner. In the case of VF coatings, alternative variation of frequency did not affect the chemical composition of matrix and only changed the content of embedded nanoparticles. The microhardness of Ni–Fe–Mn–Al₂O₃ multilayers compared to monolithic and multilayer Ni–Fe–Al₂O₃ of the same thickness was significantly increased because of Mn incorporation into the matrix. The corrosion resistance was found to be better for VD coating in comparison to the VF ones.     

Kinetics of Transformation of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> to MgO·Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Spinel Inclusions in Mg-Containing Steel

During ladle furnace refining, initial Al₂O₃ inclusions generally transform into MgO·Al₂O₃ spinel inclusions; these generated spinel inclusions consequently deteriorate the product quality. In this study, the transformation from Al₂O₃ to MgO·Al₂O₃ was investigated by immersing an Al₂O₃ rod into molten steel, which was in equilibrium with both MgO and MgO·Al₂O₃ spinel-saturated slag. A spinel layer, with a thickness of 4 μm, was generated on the Al₂O₃ rod surface just 10 s after its immersion at 1873 K (1600 °C). The thickness of the formed spinel layer increased with the immersion period and temperature. Moreover, the MgO content of the generated spinel layer also increased with the immersion period. In this study, the chemical reaction rate at 1873 K (1600 °C) was assumed to be sufficiently high, and only diffusion was considered as a rate-controlling step for this transformation. By evaluating the activation energy, MgO diffusion in the generated spinel layer was found to be the rate-controlling step. In addition, this estimation was confirmed by observing the Mg and Al concentration gradients in the generated spinel layer. The results of this study suggest that the MgO diffusion in the spinel inclusions plays a substantial role with regard to their formation kinetics.     

Construction of viscosity diagrams for CaO–SiO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–8% MgO–4% B<Subscript>2</Subscript>O<Subscript>3</Subscript> slags by the simplex lattice method

The simplex lattice method of planning experiments is used to study the viscosities of CaO–SiO₂–Al₂O₃–8% MgO–4% B₂O₃ slags in a wide chemical composition range. For each viscosity, we developed an adequate mathematical model in the form of a reduced third-order polynomial. The results of mathematical simulation are presented in composition–viscosity diagrams. Composition regions with a high fluidity of slags, the viscosities of which are 0.8–1.2 Pa s in the temperature range 1500–1600°C, are indicated in the diagrams.     

Effects of the Cr<Subscript>2</Subscript>O<Subscript>3</Subscript> Content on the Viscosity of CaO-SiO<Subscript>2</Subscript>-10 Pct Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-Cr<Subscript>2</Subscript>O<Subscript>3</Subscript> Quaternary Slag

The present study experimentally investigates the effect of Cr₂O₃ on the viscosity of molten slags. The viscosities of CaO-SiO₂-10 pct Al₂O₃-Cr₂O₃ quaternary slags with two different binary basicities (R, basic slag with R = 1.2 and acidic slag with R = 0.8) were measured by the rotating cylindrical method from 1813 K to 1953 K (1540 °C to 1680 °C). The results showed that the viscosity of both types of slag decreased as the Cr₂O₃ content increased, but the viscosity of acidic slags exhibited a greater decrease. The slags showed good Newtonian behavior at such high temperatures. Cr₂O₃ could act as a network modifier to simplify the Si-O-Si tetrahedral structure, as verified by the Raman spectral analysis, which was consistent with the decreasing trend of viscosity. The activation energy of viscous flow decreased slightly with increasing Cr₂O₃, but increasing the basicity seemed to be more effective in decreasing the viscosity than adding Cr₂O₃.     

Ordering–separation phase transitions in a Co<Subscript>3</Subscript>V alloy

The microstructure of the Co₃V alloy formed by heat treatment at various temperatures is studied by transmission electron microscopy. Two ordering–separation phase transitions are revealed at temperatures of 400–450 and 800°C. At the high-temperature phase separation, the microstructure consists of bcc vanadium particles and an fcc solid solution; at the low-temperature phase separation, the microstructure is cellular. In the ordering range, the microstructure consists of chemical compound Co₃V particles chaotically arranged in the solid solution. The structure of the Co₃V alloy is shown not to correspond to the structures indicated in the Co–V phase diagram at any temperatures.     

Synthesis of new metal-matrix Al–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–graphene composite materials

The mechanism of formation of ceramic microparticles (alumina) and graphene in a molten aluminum matrix is studied as a function of the morphology and type of precursor particles, the temperature, and the gas atmosphere. The influence of the composition of an aluminum composite material (as a function of the concentration and size of reinforcing particles) on its mechanical and corrosion properties, melting temperature, and thermal conductivity is investigated. Hybrid metallic Al–Al₂O₃–graphene composite materials with up to 10 wt % alumina microparticles and 0.2 wt % graphene films, which are uniformly distributed over the metal volume and are fully wetted with aluminum, are synthesized during the chemical interaction of a salt solution containing yttria and boron carbide with molten aluminum in air. Simultaneous introduction of alumina and graphene into an aluminum matrix makes it possible to produce hybrid metallic composite materials having a unique combination of the following properties: their thermal conductivity is higher than that of aluminum, their hardness and strength are increased by two times, their relative elongation during tension is increased threefold, and their corrosion resistance is higher than that of initial aluminum by a factor of 2.5–4. We are the first to synthesize an in situ hybrid Al–Al₂O₃–graphene composite material having a unique combination of some characteristics. This material can be recommended as a promising material for a wide circle of electrical applications, including ultrathin wires, and as a structural material for the aerospace industry, the car industry, and the shipbuilding industry.     

Structure–Property Correlation of Al–SiC–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Composites: Influence of Processing Temperatures

This paper deals with the change in the mechanical behaviour of aluminium alloy 6061 with different weight percentage of Silicon Carbide (SiC) and Alumina (Al₂O₃) ceramic powders and change in processing temperature. The crucial properties of this aluminium alloy are relatively light in weight, better corrosion resistance, wear resistance and have low production cost. These properties make them pleasant for different applications such as aerospace, defense, automotive sectors. The purpose of designing Metal Matrix Composite is to figure the desired qualities of metals and ceramics. The fabrication of the MMC was done by stir casting process. The tensile test, hardness test and impact test were performed on these composite samples to study the mechanical behaviour. The result shows that there is a significant increase in tensile strength for the samples that are processed at the temperature of 750 °C with a higher weight fraction of SiC. Also, the samples made at 850 °C exhibit better hardness and impact strength with increased content of alumina. The internal microstructure of the composites was analyzed by scanning electron microscope.     

Effects of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and CaO/SiO<Subscript>2</Subscript> Ratio on Phase Equilbria in the ZnO-“FeO”-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-CaO-SiO<Subscript>2</Subscript> System in Equilibrium with Metallic Iron

The phase equilibria and liquidus temperatures in the ZnO-“FeO”-Al₂O₃-CaO-SiO₂ system in equilibrium with metallic iron have been determined experimentally in the temperature range 1383 K to 1573 K (1150 °C to 1300 °C). The experimental conditions were selected to characterize lead blast furnace and imperial smelting furnace slags. The results are presented in a form of pseudoternary sections ZnO-“FeO”-(Al₂O₃ + CaO + SiO₂) with fixed CaO/SiO₂ and (CaO + SiO₂)/Al₂O₃ ratios. It was found that wustite and spinel are the major primary phases in the composition range investigated. Effects of Al₂O₃ concentration as well as the CaO/SiO₂ ratio on the primary phase field, the liquidus temperature, and the partitioning of ZnO between liquid and solid phases have been discussed for zinc-containing slags.