Francisco Gómez Cuevas

Bio: Francisco Gómez Cuevas is an academic researcher from University of Huelva. The author has contributed to research in topics: Sintering & Powder metallurgy. The author has an hindex of 15, co-authored 71 publications receiving 644 citations. Previous affiliations of Francisco Gómez Cuevas include University of Seville.

Porosity effect on the electrical conductivity of sintered powder compacts

Abstract: A new equation for calculating the electrical conductivity of sintered powder compacts is proposed. In this equation, the effective resistivity of porous compacts is a function of the fully dense material conductivity, the porosity of the compact and the tap porosity of the starting powder. The new equation is applicable to powder sintered compacts from zero porosity to tap porosity. A connection between this equation and the percolation conduction theory is stated. The proposed equation has been experimentally validated with sintered compacts of six different metallic powders. Results confirm very good agreement with theoretical predictions.

Electrical conductivity and porosity relationship in metal foams

Abstract: This paper presents a literature review of the experimental data and different authors’ proposed equations related to the measurement and modelling of the electrical conductivity of metal foams. The analysis is based on the classification scheme that considers two different foam categories: open-cell and closed-cell foams. A new empirical equation is presented to describe the relationship between porosity and electrical conductivity in foamed materials. The aim of this equation is to encompass the different behaviours previously described for different types of foams in a single equation.

Influence of the Total Porosity on the Properties of Sintered Materials—A Review

Abstract: Porosity is a characteristic present in most sintered materials, full densification only being achieved in special cases. For some sintered materials, porosity is indeed a desired characteristic, serving for the intended application of the material. In any case, the porosity present in materials can have a strong effect on some of their properties, both structural and functional. In this paper, some of the expressions proposed to describe the influence of the total porosity on the effective properties of sintered materials are examined. Moreover, a universal expression (with two fitting parameters) valid to satisfactorily represent all the analysed behaviours is proposed. One of these parameters can be assimilated to the tap porosity of the powders used to manufacture the material. The properties examined were elastic moduli, ultimate strength, thermal and electrical conductivities, magnetic characteristics, and other properties directly related to these ones. The study is valid for sintered materials, both metallic and ceramic, with a homogeneous and non-texturised microstructure.

Electrical Resistivity of Metal Powder Aggregates

Abstract: An equation for calculating the electrical resistivity of a compressed powder mass, consisting of oxide-coated metal particles, has been derived. In addition to the intrinsic interest of the problem, the proposed equation is useful for describing the very early stages of electrical sintering processes. The problem is approached in a new way, relating the actual powder system to an equivalent system consisting of deforming spheres in a simple cubic packing, which is much easier to examine. The proposed equation was experimentally verified from measurements of the electrical resistivity for aluminum, bronze, iron, and nickel powders under pressure. The consistency between theoretical predictions and experimental results was reasonably good in all cases.