Isaias Hilerio

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.

3D Characterization of Surface State in a Knee Prosthesis

From the medical point of view it is important that the surface roughness in a knee prosthesis be small in order to reduce the wear friction due to the physical contact of the prosthesis with bone. Given the complex form of the knee prosthesis, formerly the finishing process was carried out through a manual technique. However, this technique has many drawbacks. In this work a mechanochemical method (MCM) for finishing is proposed in order to obtain a proper surface state of the prosthesis. The selected MCM consisted of a mild wear procedure which employs HLB-11 as tensoactive additive. Composition of the knee prosthesis pieces was as follows: 26.5% Cr, 4.5% Mo, and the balance was cobalt. In order to optimize the prosthesis manufacturing, the evolution of the surface state along the finishing process was studied and a 3D analysis of the surface topography was carried out. To do this, two types of topometers were utilized, one of them with a tactile sensor and another one with an optical sensor. Fourier transform was applied to data roughness in order to determine the skweness (Rsk ) and kurtosis (Rku ) roughness values.Copyright

Computer Analysis of a Methane Fired Crucible Furnace

Two design factors and one operation parameter of a methane fired crucible furnace are numerically explored in this work. These are the number of burners, the location of the exhaust gas exit, and the air-fuel ratio, respectively. Three dimensional steady state Computational Fluid Dynamics simulations are carried out in order to analyze the influence of the above factors on the mean cavity temperature in absence of thermal load, the methane content and the oxygen content of the exit gas.

Influence in Lubricant Oxidation in Wear of Metallic Surfaces

The lubricants are certain type of substances that are applied to the contact surfaces of machines to reduce friction among the mobile parts. This friction originates a heating in pieces and wear of superficial layers. This heating produces a bad operation in parts of machines. So, lubricant protects the metallic surfaces against the action of the corrosive agents. The main part of this work consists on determining as the oxidation of lubricant influences in rubbing of the pieces and its relationship with the produced wear and their results are better in operations normal conditions when is compared when the lubricant is oxidized. The lubricant can be natural or synthetic. Among the natural lubricants it is possible to mention organic oils and minerals, fats or graphite. Among synthetic lubricants are silicones and special products able to support very high temperatures as those characteristic of advanced motors diesel. They can be coatings that allow to the mobile parts to be lubricated itself, or oils degraded without produce traces after rubbing.Copyright

Coating Characterzation in CrN Deposited by Magnetron Sputtering Method on AISI 316 Steel

Chromium Nitride (CrN) thin films were deposited on AISI steel 316 substrates by means of the reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a DC source. For the second coating a negative substrate bias voltage was applied. X ray diffraction, quantitative energy dispersion and scanning electron microscope were employed to characterize the two different phases, their chemical composition as well as their microstructure. In addition, a microhardness test was carried out. The results show that a better phase formation of CrN thin films was achieved when a heating source was present (first case). Both coatings presented homogeneous surface. Their compositions show differences even when the gases flowing are the same in composition. Regarding to the hardness test results, there can be found a higher value when using a heating source.Copyright

Numerical Analysis of Multiphase Flow in a Steel Oxygen Converter With Top and Bottom Blowing

Combined blowing in the steelmaking basic oxygen converter is a technique that allows more agitation in the metal bath, and gives a fast decarburization rate, accelerated removal of impurities and chemical and thermal homogenization. In this work the multiphase flow in an industrial-like basic oxygen converter with top and bottom blowing is analyzed by means of Computational Fluid Dynamics software. Turbulence in the converter is simulated by means of the classical K-e model given that this model yields more numerical stability during the integration for long times. Top jet velocities of Mach 1 and Mach 2, and 50 and 100 m s−1 of bottom injection velocities are used, and the results are compared with the conventional top blowing injection. Numerical results show that the combined blowing generates more agitation of the metal bath than that of the top blowing, however, from an operating viewpoint, combined blowing promotes that a significant volume of molten metal be expelled from the converter mouth.Copyright

Abrasion Under Humide Condition for Tool Steels H-13 and AISI D-2

In the present work, is developed the tribologic characterization of steels AISI H-13 and D-2, submitted to nitruration ionic process to determine wear resistance in aqueous conditions. Wear test are realized with an abrasion wear tool in an aqueous environment, designed and constructed by SEPI, ESIME, IPN, according to the norm ASTM G105-89. The aim of this investigation is to use a new material at lower prize which has an excellent wear resistance properties for high abrasion in aqueous environments, as occurs in several cases as mining industry equipments.Copyright

CFD Analysis of Multiphase Flow in a Slab Continuous Caster Mold

In order to analyze the influence of a third phase in the behaviour of the free surface profile in the mould of a slab steel continuous caster, multiphase flow in a mould water model is physically and numerically investigated. A one third scale mould water model was constructed in accordance with the Froude similarity criterion. The free surface profile in the experimental air-water system was tracked using ultrasonic level sensors which were located at six different positions along a line between the submerged entry nozzle and the mould narrow wall. Volumetric flow rates of water from 3.5×10-4 to 5.83×10-4 m3 /s were employed in the physical experiments. Three submergence depths of the nozzle, namely 0.05, 0.07 and 0.09 m, were considered. On the other hand, two and three phase transient and steady state numerical simulations were carried out by means of computational fluid dynamics software. Oil engine was employed as the third phase in the numerical simulations. A comparison between the experimental results and the numerical ones with three phases suggests significant changes in the steel-slag interface due to the presence of the third phase, particularly in the neighbourhood of the discharge of the submerged entry nozzle.Copyright

Effect of Pre Oxidation on the Sliding Wear of Multi-Component Ferrous Alloys

Presence oxides on sliding surfaces can greatly influence friction and wear. Oxides have been usually considered as a friction and wear reducing agent acting as a solid lubricant. Effects of pre-oxidation, carried out at different temperatures, on the tribological behaviour of a high-speed steel and a high chromium white cast iron sliding against a ceramic material have been studied in this work. Wear was evaluated through a new methodology, which calculates the volume of removed material from topography data of the worn surface. Wear mechanisms were determined by scanning electron microscopy analysis. Results showed a large difference between wear rate of the studied materials. High speed steel had a much lower wear than high chromium white cast iron. However pre-oxidation did not cause any meaningful influence on the tribological behaviour of both material, at least in the conditions evaluated in this work.Copyright