Gonzalez-Ojeda, Roberto
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Gonzalez-Ojeda, Roberto
Official Name
Gonzalez Ojeda, Roberto
Alternative Name
robglez
González-Ojeda, R.
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ORCID
Scopus Author ID
56314856300
Researcher ID
DTL-2716-2022

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Tribo-corrosion protection of valves and rotors using cermet layers applied with HVOF

2017 , Quintana, María José , Gonzalez-Ojeda, Roberto , Fernández, D. , Verdeja, Luis Felipe

Protection of conventional steel parts in equipment that must withstand wear of the tribo-corrosion type (combination of heat and an aqueous medium) can be achieved by High Velocity Oxy-Fuel (HVOF) techniques, applying carbide-based cermet layers which decrease tribological and corrosion mechanisms. Three different carbide layers were applied to a ferritic-pearlitic steel in order to characterize properties such as sliding friction coefficient, phase identification, adhesion to the substrate, porosity, layer thickness and wear mechanisms. An example of a real rotatory equipment after a working campaign, both with and without protective layer is presented. The capacity of the protective layer to extend the life of parts like the one analyzed is evident even if zones of the layer are detached during the campaign. © 2017, Pleiades Publishing, Ltd.

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Dmaic of structural steel parts through FEM and DOE

2016 , Gonzalez-Ojeda, Roberto , Quintana, María José , Verdeja, Luis Felipe

DMAIC in the automotive sector is applied to the design and manufacturing processes of structural steel parts in order to assess variability in mechanical properties of the raw materials, use of different types of steel in the same part, modifications in thickness of the steel sheet and even changes in geometry to produce lighter and stronger parts. The work presents an example of three stamped automotive structural components, mechanically interacting together when deformed under load. Minitab design of experiments module was used to evaluate two level factors, one of them being the thickness of each part, and the other the material properties: DP600, DP780 steel or a boron-based steel alloy. A FEM model of the three parts, with structural supports and loads, was performed to evaluate displacement of the system, max. equivalent stress, strain and total weight, allowing data correlation to determine best practices to accomplish low weight, high stiffness designs. Copyright © 2016 MS&T16®.

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Machinability Improvement Through Heat Treatment In 8620 Low-Carbon Alloyed Steel

2009 , Verdeja, Luis Felipe , Verdeja, José Ignacio , Gonzalez-Ojeda, Roberto

The effect of different heat treatments is evaluated on SAE 8620 low-carbon alloyed steel by means of drilling tests. Improving machinability through prior heat treatment in steels used for nitro-carburizing surface treatments is very important in the manufacturing of large series of parts, due to its impact in production costs. This is the case for the commonly used SAE 8620 grade, in its carburized and quenched and tempered state, for the production of gears, shafts and other transmission box components for the automobile industry. The machinability of the steel, determined by simple drilling tests (which are typical in industry labs), is a function of microstructure, which is determined by the state in which the steel is received and/or heat treatments prior to carburizing. This work shows that by employing some inter-critic annealing treatments, followed by sub-critic isothermal ones, the machinability of 8620 steel can be improved by ∼16% over the typical as-received cold drawn state.

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Using FEM to determine temperature distribution in a blast furnace crucible

2000 , Verdeja, Luis Felipe , Gonzalez-Ojeda, Roberto , Ordóñez, Alejandro

Temperature distribution in the crucible of a blast furnace is an important operation variable that is a function of the materials used in its construction, temperatures reached in the pig iron-refractory interface, and cooling-system performance. Defining the crucible zones where high shear and tensile stresses are reached is an important step in developing a tribological model to understand and predict high wear zones and crucible life. In this work, temperature distribution was simulated using the finite-element method for a blast furnace built following the ceramic solution (oxide and nitride ceramics in contact with the pig iron and carbon and microporous graphite blocks in contact with the refrigeration system).

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