Experimental study of phase equilibria in the PbO-ZnO-“Fe2O3”-CaO-SiO2 system in air for high lead smelting slags (CaO/SiO2=0.35 and PbO/(CaO + SiO2)=5.0 by weight)

Experimental studies on phase equilibria in the multicomponent system PbO-ZnO-CaO-SiO₂-FeO-Fe₂O₃ in air have been conducted to characterize the phase relations of a complex slag system used in commercial lead oxidation smelting. The liquidus in the pseudo-ternary section ZnO-“Fe₂O₃”-(PbO + CaO + SiO₂) with the CaO/SiO₂ weight ratio of 0.35 and the PbO/(CaO + SiO₂) weight ratio of 5.0 has been constructed using results of over 100 high-temperature equilibration and quenching experiments followed by electron probe X-ray microanalysis. The liquidus in this pseudoternary section contains primary phase fields of spinel (zinc ferrite) Zn _x Fe_3−x O_4+y , zincite Zn _u Fe_1−u O, melilite Pb _v Ca_2−v Zn _w Fe_1−w Si₂O₇, hematite Fe₂O₃, magneto-plumbite PbFe₁₀O₁₆, and dicalcium silicate Ca_2−t Pb _t SiO₄. The laboratory results are compared with the slags obtained from an industrial reactor.     

Polygonal multiresolution topology optimization (PolyMTOP) for structural dynamics

We use versatile polygonal elements along with a multiresolution scheme for topology optimization to achieve computationally efficient and high resolution designs for structural dynamics problems. The multiresolution scheme uses a coarse finite element mesh to perform the analysis, a fine design variable mesh for the optimization and a fine density variable mesh to represent the material distribution. The finite element discretization employs a conforming finite element mesh. The design variable and density discretizations employ either matching or non-matching grids to provide a finer discretization for the density and design variables. Examples are shown for the optimization of structural eigenfrequencies and forced vibration problems.     

Level‐set topology optimization with many linear buckling constraints using an efficient and robust eigensolver

Linear buckling constraints are important in structural topology optimization for obtaining designs that can support the required loads without failure. During the optimization process, the critical buckling eigenmode can change; this poses a challenge to gradient‐based optimization and can require the computation of a large number of linear buckling eigenmodes. This is potentially both computationally difficult to achieve and prohibitively expensive. In this paper, we motivate the need for a large number of linear buckling modes and show how several features of the block Jacobi conjugate gradient (BJCG) eigenvalue method, including optimal shift estimates, the reuse of eigenvectors, adaptive eigenvector tolerances and multiple shifts, can be used to efficiently and robustly compute a large number of buckling eigenmodes. This paper also introduces linear buckling constraints for level‐set topology optimization. In our approach, the velocity function is defined as a weighted sum of the shape sensitivities for the objective and constraint functions. The weights are found by solving an optimization sub‐problem to reduce the mass while maintaining feasibility of the buckling constraints. The effectiveness of this approach in combination with the BJCG method is demonstrated using a 3D optimization problem. Copyright © 2016 John Wiley & Sons, Ltd.     

Investigation of Freeze Lining in Copper-Containing Slag Systems: Part III. High-Temperature Experimental Investigation of the Effect of Bath Agitation

Freeze-lining technologies have been employed to protect the cooling walls of reactors from chemically aggressive molten reactants. To date, the designs of freeze linings for pyrometallurgical reactors have been based on the basic assumption that the interface between the deposit and the bath remains at the liquidus temperature of the bulk liquid. There is, however, increasing evidence that interface temperature between stagnant deposit and bath is less than the liquidus of the bulk liquid. A previous study also demonstrated that the effects of bath chemistry need to be taken into account in freeze-lining designs. To investigate the fundamental processes involved in the formation and stability of the deposit, experimental laboratory studies have been undertaken in the Cu-Fe-Si-Al-O slag system in equilibrium with metallic copper using an air-cooled probe technique. In the current study, the effects of bath agitation on the microstructure, morphologies of the phases, and formation of various layers across the freeze-lining deposit were studied at steady-state conditions. It appears that the changes in the fluid flow pattern through changes in shear intensities result in corresponding changes in the deposit microstructure, formation of the sealing primary phase layer, thus influencing the interface temperature between freeze-lining deposit and the liquid bath.     

Experimental Study of Ferrous Calcium Silicate Slags: Phase Equilibria at {\text{P}}_{{{\text{O}}_{2} }} Between 10?5?atm and 10?7?atm

Ferrous calcium silicate slags, whose principal components are “FeO _x ”-CaO-SiO₂, are widely used in copper smelting and converting operations. In the current study, high-temperature equilibration and rapid quenching techniques were used to study the phase equilibria of the ferrous calcium silicate slags. The compositions of phases in the slags were measured accurately using electron probe X-ray microanalysis (EPMA). The phase equilibria of the system have been characterized at oxygen partial pressures between 10⁻⁵ atm and 10⁻⁷ atm at selected temperatures between 1473 K and 1623 K (1200 °C and 1350 °C). The effects of oxygen partial pressure and temperature on the compositions of phases in the slags are presented.     

Investigation of the Influence of Heat Balance Shifts on the Freeze Microstructure and Composition in Aluminum Smelting Bath System: Cryolite-CaF2-AlF3-Al2O3

Metallurgical and Materials Transactions B - In an aluminum electrolysis cell, the side ledge forms on side walls to protect it from the corrosive cryolitic bath. In this study, a series of...     

Metallic micro displacement capacitive sensor fabricated by laser micromachining technology

This paper presents design, fabrication and performance testing results of the micro displacement capacitive microsensor fabricated by femtosecond laser machining technology. The microsensor having overall dimensions of 1,275 (W)×1,153 (L) μm consisted of 20 pairs of comb fingers of 24 (W)×300 (L) μm with a gap between the fingers of 6 μm, suspension springs, inertial mass and support anchors. The sensor structure was fabricated from a 25 μm thick tungsten foil. The fabricated microsensor was able to deliver 230 fF capacitance variations for measured displacements up to 25 μm. The results on the performance testing and geometry evaluation under pins the laser micromachining technology as an effective tool to fabricate miniature functional components and mechanisms. The developed microsensor can be used for micro/nano scale displacement measurements in MEMS applications.     

Coupled experimental and thermodynamic study of the Zn-Fe-Si-O system

Experimental and thermodynamic modeling studies have been carried out on the Zn-Fe-Si-O system. This research is part of a wider program to characterize zinc/lead industrial slags and sinters in the PbO-ZnO-SiO₂-CaO-FeO-Fe₂O₃ system. Experimental investigations involve high-temperature equilibration and quenching techniques followed by electron probe X-ray microanalysis (EPMA). Liquidus temperatures and solid solubilities of the crystalline phases were measured in the temperature range from 1200 °C to 1450 °C (1473 to 1723 K) in the zinc ferrite, zincite, willemite, and tridymite primary-phase fields in the Zn-Fe-Si-O system in air. These equilibrium data for the Zn-Fe-Si-O system in air, combined with previously reported data for this system, were used to obtain an optimized self-consistent set of parameters of thermodynamic models for all phases.