Characterization of a soldering system consisting of a glass from the system CaOAl2O3B2O3SiO2 and wollastonite

In this work, the characterization of a soldering system with wollastonite as filler added as powder to the powdered base glass is shown. A soldering system consisting of the base glass and a coexisting crystalline phase is created which is then pressed to pellets and sintered to maximum density.Wollastonite increases the thermal expansion coefficient of the base glass after sintering the samples. In the present paper, the sintering behavior of the soldering system and possible interactions between glass and filler are analyzed. Also, density and porosity after sintering and the resulting crystalline phases are characterized.The mixtures with wollastonite contents up to 30% showed suitable sintering behavior and good density (low porosity). From 40% wollastonite on, the sintering of the samples was not satisfying and porosity was still high after sintering. The main crystalline phases were anorthite, wollastonite and pseudowollastonite, which occurred in all samples. This shows that all three phases are coexisting phases of the glass composition.     

Intrinsic stress evolution in diamond films prepared in a CH4H2NH3 hot filament chemical vapor deposition system

The intrinsic stress in diamond films prepared in a CH₄H₂NH₃ hot filament chemical vapor deposition system has been investigated by the substrate curvature technique as a function of film thickness (2.2–50 μm) and ammonia concentration (0–1.4%). Our results indicated that the film stress changed from compressive to tensile with the increase of film thickness and diamond quality at a constant ammonia concentration of 0.5%. The existence of a non-diamond phase was found to be beneficial to the relaxation of intrinsic tensile stress in the films. The intrinsic stress in diamond films was tensile at an ammonia concentration from 0 to 1.4%, while the maximum tensile stress existed at 0.75% NH₃. The possible origin of intrinsic tensile stress was discussed.     

Potential of integrating Na2SO4 · 10H2O pellets in solar drying system

In the current study, evolution of thermophysical properties of red chilli dried in a mixed mode solar dryer that integrates sodium sulfate decahydrate (Na₂SO₄?·?10H₂O) and sodium chloride (NaCl) as thermal storage were presented. Solar drying with Na₂SO₄?·?10H₂O reduced the drying time by 26.7 and 39%, compared to the drying time with or without NaCl. Dimensional shrinkage was gradual with a nonlinear exponential shape for the whole drying conditions. The evolution of the bulk and particle densities decreased while the porosity of the seed increased with time. The coefficient of heat and mass transfer varied from 0.0036???0.035?W/m²?K to 6.09?×?10^?9???6.2?×?10^?8?m/s, respectively. The thermal conductivity, specific heat capacity, and thermal diffusivity ranged from 0.0568 to 0.1093?W/m?K, 1,072 to 2218.7?J/kg?K, and 4.7?×?10^?5 to 5.13?×?10^?5?m²/s, respectively.     

Quantitative determination of fly ash in the hydrated fly ash - CaSO4·2H2OCa(OH)2 system

For the quantitative determination of fly ash in hydrated fly ash - CaSO₄·2H₂OCa(OH)₂ system, various kinds of selective dissolution were evaluated using pastes made from a single representative fly ash. Selective dissolution using picric acid-methanol solution was found to be adequate. Selective dissolution using picric acid - methanol + water can also be used, when it is necessary to save time, although rather bigger corrections are needed. Reproducibility of the determination by both methods was found to be satisfactory, as the standard deviation of the measurement was within 0.23 – 0.55%. Several dissolution experiments were also carried out to obtain the basic information related to this technique.     

Adhesion improvement of electroless copper to PC substrate by a low environmental pollution MnO2–H3PO4–H2SO4–H2O system

A low environmental pollution etching system, MnO₂–H₂SO₄–H₃PO₄–H₂O colloid, was used to investigate surface etching performance of polycarbonate (PC) as a replacement for the chromic acid etching solution. The effects of H₂SO₄ concentrations, H₃PO₄ concentrations and etching times upon the surface topography, surface chemistry and surface roughness were studied. With the appropriate etching treatment, the surface average roughness (R_a) of PC substrates increased from 3 to 177 nm, and the adhesion strength between the electroless copper and PC substrate also reached 1.10 KN m⁻¹. After the etching treatment, the PC surface became hydrophilic and the surface contact angle decreased from 95.2° to 24.8°. The intensity of C–O groups increased and the new functional groups (–COOH) formed on the PC surface with the etching treatment, which improved the adhesion strength between PC substrate and elctroless copper film.     

Behaviour of the FeOSH system under coal liquefaction conditions

The behaviour of the iron-sulphur system in the presence of water and hydrogen under coal liquefaction conditions has been investigated by using a high-pressure differential thermal analysis technique. The iron compounds used were Fe₂O₃, Fe₃O₄ and FeS₂. DTA was performed under 10.1 MPa (initial pressure) N₂ or H₂, heating to 450 °C (2.5 °C min⁻¹). Sulphate ions were detected by BaCl₂ addition to the product aqueous solution; sulphides were formed as gaseous and solid products. The results suggest that the catalytic behaviour of the sulphate and sulphides formed under the conditions employed must be considered for the iron-sulphur system in coal liquefaction.     

CH⋯O,OH⋯O and π⋯π interactions in the crystal structure of a new heterotrinuclear macrocyclic complex, [MnII(NiIIL)2(C2H5OH)2](ClO4)2

The title complex was synthesized and characterized by X-ray crystallography. Mn^II ion is in a distorted octahedral environment. The coordination geometries around two Ni^II ions are completely same and are slightly distorted square planar. Mn^II and each Ni^II are bridged by an oxamido-group from one of the two macrocyclic ligands (L). CH⋯O, OH⋯O and π⋯π interactions link the trinuclear fragments and perchlorate ions to form a 3-D supramolecular architecture.     

Synthesis of tributyl citrate catalyzed by Ce(SO4)2·4H2O/ NH2SO3H

研究了柠檬酸与正丁醇在Ce(SO₄)₂·4H₂O/ NH₂SO₃H复配催化剂催化作用下制备柠檬酸三丁酯的工艺条件。实验结果表明Ce(SO₄)₂·4H₂O/ NH₂SO₃H催化合成柠檬酸三丁酯的最佳反应条件为：醇酸摩尔比为4.0∶1,催化剂用量为1.5%（以柠檬酸质量计）,m[Ce(SO₄)₂·4H₂O]∶m(NH₂SO₃H)=2∶1,反应温度为150 ℃,反应时间为7 h,酯化率＞98.5%,精制后产品纯度>99.5%。     

Phase relations between Al2O3Cr2O3 and FeAl2O4FeCr2O4 solid solutions at 1823 K

Tie-lines between the corundum and spinel solid solutions have been determined experimentally at 1823 K. Next, activities of FeCr₂O₄ and FeAl₂O₄ in the spinel solid solution were determined by combining the tie-line data with literature values for the activities of Cr₂O₃ and Al₂O₃ in the corundum phase. Activities and the Gibbs energy of mixing for the spinel solid solution were also obtained from a model based on cation distribution between nonequivalent crystallographic sites in the oxide lattice. The difference between the Gibbs energy of mixing obtained experimentally and from the model has been attributed to a strain enthalpy term which is relatively unchanged in magnitude from the reported at 1373 K. The integral enthalpy of mixing obtained from experimental data at 1373 and 1823 K using the second law is compared with the model result.     

Kinetics of heterophase interaction in the system CaCo3 — Al2O3 — H3PO4

The main phosphate phases responsible for formation of the structure in a phosphate-bearing binder are determined. Kinetic studies of interphase interaction in the system CaCO₃ — Al₂O₃ — H₃PO₄, the fundamental chemistry and the direction of the reactions of phase formation, the reaction rates for the reagents (CaCO₃, A1₂O₃, aluminates), and the overall equation of the rate of assimilation of H₃PO₄ are presented.     

Single crystal structure of a two-dimensional framework: [{Co(4,4′-bpy)(HO3PCH2CH2CH2CH2PO3H)(H2O)2}·4H2O]n

The structure of [{Co(4,4^′-bpy)(HO₃PCH₂CH₂CH₂CH₂PO₃H)(H₂O)₂}·4H₂O]_n 1 was determined by single crystal X-ray diffraction. Compound 1 contains a new two-dimensional framework layer, which is built up from parallelogram units in bc plane. The layers are constructed into a three-dimensional structure by interlayer hydrogen bonds.     

Role of support in CO2 reforming of CH4 over a Ni/γ-Al2O3 catalyst

A catalyst of 10% Ni/γ-Al₂O₃ for CO₂/CH₄ reforming was prepared and characterized by TPR, TPD, XPS, XRD and activity measurements. XPS and TPR showed that Ni mainly exists in the form of NiAl₂O₄ in the calcined catalyst and is hard to reduce below 650°C, indicating a strong interaction between metal and support. Reduction of the calcined catalyst results in fine particles of Ni⁰, with an average diameter of about 20 nm as determined by XRD. The uptake of H on the reduced catalyst measured by H₂-TPD is 4.2–4.6 mole per mole of Ni species and does not depend on the reduction degree of Ni species. This provides a convincing piece of evidence for the occurrence of hydrogen spillover in the reduced catalyst. Only reduced catalysts present good activity, but the degree of nickel reduction has almost no effect on the reforming activity. This seems to suggest that Ni⁰ is vital for the reforming activity, but γ-Al₂O₃ is also involved in CO₂/CH₄ reforming and contributes even more. Based on the mechanism proposed by Bradford et al. and on our observations, a mechanistic model has been proposed to elucidate the role of γ-Al₂O₃ in CO₂/CH₄ reforming.     

Stability in the system CaO–Al2O3–H2O

The solubility of AH₃, CAH₁₀, C₂AH_7.5, and C₃AH₆ was determined experimentally at 7 to 40 °C and up to 570 days. During the reaction of CA, at 20 °C and above initially C₂AH_7.5 formed which was unstable in the long-term. The solubility products calculated indicate that the solubilities of CAH₁₀, C₂AH_7.5 and C₄AH₁₉ increase with temperature while the solubility of C₃AH₆ decreases. Thus at temperatures above 20 °C, C₃AH₆ is stable, while at lower temperature also CAH₁₀ and C₄AH₁₉ are stable, depending on the C/A ratio.At early hydration times, CAH₁₀ can be stable initially at 30 °C and above, as the formation of amorphous AH₃ stabilises CAH₁₀ with respect to C₃AH₆ + 2AH₃. With time, as the solubility AH₃ decreases due to the formation of microcrystalline AH₃, CAH₁₀ becomes unstable at 20 °C and above.     

Stabilite thermodynamique des phases dans le systeme CaOAl2O3CO2H2O

The paper presents a theoretical investigation on the nature of thermodynamical stable precipitating phases in the CaOAl₂O₃CO₂H₂O system when monocalcium aluminate (CA) with or without an excess of lime or alumina is mixed with water in equilibrium with gaseous carbon dioxide. Basing on the nature of ions in solution (A10₂⁻, Ca⁺⁺, CO_{3_}⁻⁻, OH⁻ and H⁺). and supposing that only $\text{C}\text{C}$, AH₃, CH, CAH₁₀, C₂AH₈ and C₄ACH₁₁ are the possible stable phases, the system was mathematically described taking into account the values of solubility products, the equilibrium between atmospheric carbon dioxide and the solution, ionic dissociation constant of water, matter balance of calcium and aluminate ions and condition of the solution electroneutrality. For a given system of initial parameters, computer calculation has allowed to determine the only possible solid-liquid system among the 22 theoretically possible cases (zero, one or two solids in equilibrium with the solution). So, varying the initial parameters has led to draw isobaric and isosteric phase diagramms, what shows that, in the conditions of the study, CAH₁₀ is the only stable phase at 21°C. The result suggests that the precipitation of C₂AH₈ and $\text{C}{}_4\text{A}\text{C}\text{H}{}_{11}$ can only be a consequence of saturations of the solution with respect to CAH₁₀.     

Phase diagram of the Li2SO4–Na2SO4 system

The thermal analysis and X-ray powder diffraction studies of the Li₂SO₄–Na₂SO₄ system, including the high-temperature X-ray diffraction technique, have elucidated four phases of variable composition: three solid solutions based on the α-Li₂SO₄, α-Na₂SO₄, and α-LiNaSO₄ high-temperature polymorphs, and a low-temperature β-LiNaSO₄ phase. α-Na₂SO₄-Base solid solution disintegrates into two phases via a monotectoid phase transformation. It is quite probable that the monotectoid process is related to the conversion of the second-order phase transition to the first-order phase transition.     

High-pressure behavior and phase stability of Na2B4O6(OH)2·3H2O (kernite)

The high-pressure behavior of kernite [ideally Na₂B₄O₆(OH)₂·3H₂O, a ~ 7.02 Å, b ~ 9.16 Å, c ~ 15.68 Å, β = 108.9°, Sp Gr P2₁/c, at ambient conditions], an important B-bearing raw material (with B₂O₃ ≈ 51 wt%) and a potential B-rich aggregate in radiation shielding materials, has been studied by single-crystal synchrotron X-ray diffraction up to 14.6 GPa. Kernite undergoes an iso-symmetric phase transition at 1.6-2.0 GPa (to kernite-II). Between 6.6-7.5 GPa, kernite undergoes a second phase transition, possibly iso-symmetric in character (to kernite-III). The crystal structure of kernite-II was solved and refined. The isothermal bulk modulus (K_V0 = β^-1_P0,T0, where β_P0,T0 is the volume compressibility coefficient) of the ambient-pressure polymorph of kernite was found to be K_V0 = 29(1) GPa and a marked anisotropic compressional pattern, with K(a)₀: K(b)₀: K(c)₀~1:3:1.5., was observed. In kernite-II, the K_V0 increases to 43.3(9) GPa and the anisotropic compressional pattern increases pronouncedly. The mechanisms, at the atomic scale, which govern the structure deformation, have been described.