The Influence of Sand Grains Properties on Electrical Properties of Moulding Sand with Inorganic Binder

Abstract

The paper presents the results of basic research on the influence of the properties of sand grains on electrical properties of water glass moulding sands. It shows electrical properties of the main component – sand grains, crucial to the kinetics of moulding sands heating, such as permittivity εr and loss factor tgδ. Measurements were carried out with the use of the perturbation method for silica, chromite and olivine sands of different mineral, chemical composition and particle size distribution, as well as for moulding sands with water glass grade 145. Analysis of the results of measurements of electrical properties shows that all moulding sands are characterized by a similar permittivity εr and loss factor tgδ. It was found that the electrical properties and the quantity and quality of other components may have a decisive influence on the effectiveness and efficiency of the microwave heating of moulding sands with sand grains. In determining the ability to efficiently absorb the microwave radiation for mixtures which moulding sands are, the impact of all components influencing their individual technological parameters should be taken into account.

In situ monitoring of used-sand regeneration in foundries by impedance spectroscopy

“…Among the first non-standardized measurement methods for monitoring sand properties are, for example, methods based on microwave technology (Opyd and Granat, 2015;Stachowicz, 2016). The actual aim of these investigations is to determine the power component of the microwave that leads to the heating of the sand-binder mixture.…”

“…As a by-product of this re-search, it has been shown that, in particular, the reflected microwave power contains information about the density of the molding material bulk (Stachowicz, 2016). Other groups in the field of microwave technology use the disturbance of cavity resonators to investigate material properties of molding sands (Opyd and Granat, 2015). Other approaches deal with the introduction of traditional sensor technology, such as thermocouples, in order to be able to follow thermal processes during casting.…”

“…In addition, this measurement method is limited to dielectric materials, whose relative permittivity must not be too high and, if possible, must not exhibit any electrical conductivity (Balmus et al, 2006). Also, one has to keep an eye on the information density because one typically measures the resonant frequency of the cavity and infers the relative permittivity of the material from it; i.e., one obtains only one data point (Opyd and Granat, 2015).…”