Thermal Transformations of an Aluminoborophosphate Binder

Thermal transformations of a commercial aluminoborophosphate binder are studied in a broad temperature range by optical microscopy, x-ray diffraction, IR spectroscopy, and thermal analysis. The introduction of B₂O₃ reduces the temperature of phosphate polycondensation, enhances the stability of cyclometaphosphates in a broad temperature range (180–1100°C), and reduces the stability of hydrogen phosphates.     

Composition, Structure, and Thermal Expansion of Ca3Fe4S3O6 and CaFeSO

The iron calcium oxysulfides Ca₃Fe₄S₃O₆ and CaFeSO are synthesized by reacting mixtures of CaO and FeS in an inert atmosphere. Their elemental compositions and lattice parameters are determined by x-ray microanalysis and x-ray diffraction. From the temperature-dependent lattice parameters of the oxysulfides (measured up to 1020 K), their thermal expansion coefficients are evaluated.     

Synthesis and Sintering of Bi2Ti4O11

The conditions of Bi₂Ti₄O₁₁ formation are studied. It is shown that the process is diffusion-controlled and depends significantly on the heating rate. The optimal conditions for producing Bi₂Ti₄O₁₁ ceramics are determined. Cold pressing of Bi₂Ti₄O₁₁ ceramic powder at high pressures is shown to influence the unit-cell parameters and volume, positional parameters of Bi and Ti, and bond distances in the ferroelectric ceramics produced by subsequent sintering. The ferroelectric transition temperature decreases steadily with increasing densification pressure.     

Synthesis and Study of Ion Adsorption and Fluorescent Properties of Silica-Grafted Bis(crownazo)methine

A ketocyanine ligand containing two N-aza-15-crown-5 residues has been synthesized and covalently anchored to a silica substrate through an azomethine link. The ligand formation and molecular structure have been determined by combining spectral data and molecular simulations. Preferential adsorption of rare-earth metals from aqueous solutions to the modified surface has been noticed. In the case of lanthanum, the adsorption is accompanied by significant fluorescence enhancement, which allows this system to be used as a sensor for La³⁺ ion.     

Stability of a floating cylinder

A cylinder having a length less than 0.707 of its diameter will float with its axis vertical while one of length exceeding one diameter floats with its axis horizontal. This transition range was investigated and under certain circumstances, two stable positions of the cylinder axis were found in each quadrant of rotation. Details of behaviour in the transition range were attributed to the edges of the square-ended cylinder.     

Reduced modified quadratures for quadratic membrane finite elements

Reduced integration is frequently used in evaluating the element stiffness matrix of quadratically interpolated finite elements. Typical examples are the serendipity (Q8) and Lagrangian (Q9) membrane finite elements, for which a reduced 2 × 2 Gauss–Legendre integration rule is frequently used, as opposed to full 3 × 3 Gauss–Legendre integration. This ‘softens’ these element, thereby increasing accuracy, albeit at the introduction of spurious zero energy modes on the element level. This is in general not considered problematic for the ‘hourglass’ mode common to Q8 and Q9 elements, since this spurious mode is non‐communicable. The remaining two zero energy modes occurring in the Q9 element are indeed communicable. However, in topology optimization for instance, conditions may arise where the non‐communicable spurious mode associated with the elements becomes activated. To effectively suppress these modes altogether in elements employing quadratic interpolation fields, two modified quadratures are employed herein. For the Q8 and Q9 membrane elements, the respective rules are a five and an eight point rule. As compared to fully integrated elements, the new rules enhance element accuracy due to the introduction of soft, higher‐order deformation modes. A number of standard test problems reveal that element accuracy remains comparable to that of the under‐integrated counterparts. Copyright © 2004 John Wiley & Sons, Ltd.     

Stability of Circular Cylindrical Shells with a Single Local Dent

The theoretical-and-experimental investigation has been performed on the stability of smooth cylindrical shells of steel with a single local dent. All the shells manufactured using the same process were tested with the fulfillment of identical conditions for observations and measurements. Theoretical calculations were carried out by the mesh method with the use of the nonlinear theory of shells. A comparison of the experimental and theoretical values of the critical loads has been made. The theoretical-and-experimental approach proposed enables one to evaluate the quality of shells by studying local dents and other specific imperfections.     

Life Calculations for Header – PGV-1000 Steam Generator Connector Weld Joints under NPP Service Conditions

The procedure for calculating the life of header – steam generator connector weld joints is proposed. It allows for running out the material plasticity reserve upon static cyclic elastoplastic loading as well as operating conditions, local stress concentrations, and residual stresses after welding.     

Fracture Resistance of Ceramics upon Edge Chipping

Modern methods of determining fracture resistance are analyzed. The necessity of developing a crucially new method based on edge chipping of a brittle material is shown. The results of experimental studies are presented. The applicability of the method to the comparative fracture resistance evaluation of ceramics is substantiated.