Gabriel Plascencia

Analysis of Nanocrystalline Intermetallic Compounds from their X-Ray Diffraction Patterns

Synthesis of intermetallic PbSe induced by high-energy ball milling has been studied. Systematic analysis of transformation in the resulting phases of milling from 0 to 10 h has been traced by characterizing the microstructures in terms of morphology, crystallite size, and percentages of phases formed as a function of milling time. Results reveal the formation of two phases. Where the system of PbO-Se transforms gradually to PbSe. Complete transformation is achieved after 10 h of milling time. Study of particle structure by the Rietveld Method further corroborates the value of the nano-order crystallite diameters as evaluated from the microscopic studies.

Influence of the Slag Density on the Splashing Process in a Steelmaking Converter

The way in which slag density influences the slag splashing phenomenon in an oxygen steelmaking converter is numerically analyzed in this work. Several values of the density of the slag are considered, and their effect on the global mass balance and slag average volume fraction on the sidewalls of the converter is studied using isothermal, two-dimensional transient computational fluid dynamics simulations. Diameter of the slag drops is determined from the slag density and the impact velocity of the nitrogen jet. Besides, the effect of the nitrogen jet Mach number on the slag splashing is simulated and discussed. A qualitative comparison between the computer simulations and results from the literature is made.

Numerical Analysis of Oscillation Death in Coupled Self-Excited Elastic Beams

The emergence of the oscillation death phenomenon in a ring of four coupled self-excited elastic beams is numerically explored in this work. The beams are mathematically represented through partial differential equations which are solved by means of the finite differences method. A coupling scheme based on shared boundary conditions at the roots of the beams is assumed, and as initial conditions, zero velocity of the first beam and three normal vibration modes of a linear elastic beam are employed. The influence of the self-exciting constant on the ring dynamics is analyzed. It is observed that oscillation death arises as result of the singularity of the coupling matrix.

Mass Transfer Kinetics in the Desulphurisation of Pig Iron with CaO and CaC2

This paper discusses the effect of the main parameters that affect the desulphurization reaction efficiency. The study was conducted by evaluating different reaction sites within the metal, the slag and the reducing agents. It was possible to establish a mass transfer model that determines the amounts of the reducing agents needed to maintain adequate sulphur levels in the pig iron. Industrial trials showed the accuracy of our model.

Design of an Induction Glass Melting Furnace by Means of Mathematical Modelling Using the Finite Element Method

In this paper we propose the design of a novel induction furnace for glass melting. The design is based on a mathematical analysis and performed numerically by means of the Finite Element Method. Several induction coils configurations were tested. The results from the mathematical model show that it is possible to melt glass in a furnace whose hearth is no larger than half a metre by using axial induction coils and high frequencies. This furnace configuration may result in increased glass melting rates along with the elimination of harmful emissions.

Rate of Reduction of Chromium Oxides in a Slag by FeSi and FeMgSi Ferroalloys

The rate of reduction of chromium oxides in a stainless steel slag was studied in stagnant slag / metal melts at 1600 °C. The experimental results show that the magnesium contained in a FeMgSi ferroalloy has a reduction potential comparable to that of the silicon in a FeSi ferroalloy. On the other hand, it was confirmed that the rate limiting step in the reduction of the chromium oxides is the transport of chromium from the bulk of the slag to the slag / metal interface. The mass transfer coefficients for the reduction of chromium were estimated and are in good agreement with previously reported values.

Laws of Thermodynamics and Auxiliary Functions

Thermodynamics developed from studying the efficiency of early steam engines. Thermodynamics deals with energy exchange or energy transformation in a given system without considering any molecular mechanism. At its core, thermodynamics relates heat and temperature to energy and mechanical work.

Phase Equilibria I

In the previous chapter, it was discussed the thermodynamics principles that are the basis of thermochemistry. It was shown how to calculate the energy involved in any chemical or physical transformation. Additionally, it was established the Gibbs free energy as a criterion to know whether or not such transformations would take place under a given set of conditions.

Phase Equilibria II

In the last chapter, interactions between components forming mixtures were discussed. As more constituents were added to the system, the equations describing the thermodynamic quantities become more complex. However, it was shown in the examples section that graphical representation of such equations is very useful in determining those quantities.

Mixing and Solution Thermodynamics

In nature, we rarely find pure components or elements. We live in a world made of mixtures; therefore, we should shift our attention to mixtures components in solids, liquids, and gases. Because of this, we are more interested in the thermodynamics of mixing.