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An important issue in obtaining a good casting surface without defects in contact with the liquid metal is the use of protective coatings on the surface of the moulding sand forming the mould cavity. Protective coatings are based on highly refractory materials that are finely ground and protect the moulding sand from thermal stresses from the molten metal. An important aspect of obtaining the appropriate properties of the protective coatings used is the method of application. This article presents the results of a quality study of the protective coatings obtained, which were applied by dip and painting with a brush. Four different coatings were applied to mould sand samples prepared on grain matrices with different average grain sizes. During the tests, the viscosity of the protective coatings, their gas-forming capacity, sieve analyses of the grain matrix used, the permeability of the moulding sand with the protective coating and the abrasiveness and adhesion of the protective coatings were determined. The quality of the coating obtained was found to depend on its type, the size of the grain matrix used in the moulding sand and the method of application. The experiments carried out indicate that a comparative study of the available protective coatings can indicate the best solution, taking into account the grain matrix used and the method of application adopted. [ABSTRACT FROM AUTHOR]

The technique of differential impedance analysis (DIA) has shown promising results in identifying appropriate model orders when applied to electrochemical impedance spectroscopy (EIS) measurements of a given medium. However, even with this method it remains challenging to reliably deduce general material properties of the medium from impedance data alone. Here, we discuss a number of possible extensions and modifications of the technique and, in particular, an extension of the process from mere model order identification to a complete modelling approach. In addition, the combination of DIA and machine learning methods to predict material properties is explored. Our results were validated with impedance measurements between 20 Hz and 1 MHz of moulding sand containing varying amounts of quartz and chromite sand as well as bentonite and carbon. [ABSTRACT FROM AUTHOR]

In the current scenario the demand for reduction of silica sand usage in making sand moulds in the metal casting industry is increasing day by day. The non-silica alternatives will help the foundries to not only get in line with new regulations but also protect the foundry workers and minimizing the compliance costs. The non-silica alternatives such as clay, bio-waste, bagasse-ash and nano-SiO2 in different proportions are added to silica sand to prepare moulding sand. The effect of these alternatives on mould sand properties such as permeability, green shear strength and green compression strength are studied. The aluminium alloy 6061 castings were fabricated in the sand mould prepared using these non- silica alternatives. Effect of these materials on the grain size, surface roughness and mechanical properties of aluminium alloy 6061 castings were studied. Out of all, the silica sand/15%bagasse-ash combination was found more suitable for producing aluminium alloy 6061 castings with high yield strength, ultimate tensile strength and low surface roughness values. The ranking of combinations based low surface roughness and high strength values of aluminium alloy 6061 castings is, bagasse-ash > bio-waste > nano-SiO2 > clay. [ABSTRACT FROM AUTHOR]

This paper deals with the issue of using moulding sands with a new two-component binder: furfuryl-resole resin - PCL polycaprolactone for the production of ductile iron heavy castings. The previous laboratory studies showed the possibility of using biodegradable materials as binders or parts of binders' compositions for foundry moulding and core sands. The research proved that addition of new biodegradable PCL in the amount of 5% to the furfuryl-resole resin does not cause significant changes in moulding sand's properties. The article presents research related to the production of ductile iron castings with the use of moulds with a modified composition, i.e. sands with furfuryl resole resin with and without PCL. Mechanical properties and microstructure of the casting surface layer at the metal/mould interface are presented. The obtained test results indicate that the use of a biodegradable additive for making foundry moulds from moulding sand with a two-component binder does not deteriorate the properties of ductile iron castings. [ABSTRACT FROM AUTHOR]

This study considered the effect of the Covid-19 pandemic on the economy of Nigeria and investigated the effective application of foundry technology to proffer a sustainable solution to the problem. Domestication of production of motorcycle components, being a significant means of transportation that is required for the development of any society was considered. Aluminium scraps from a waste dump and Belle and Oyun natural moulding sands in Kwara State, Nigeria, which have been previously recommended for non-ferrous casting in previous studies were considered and used for casting of motorcycle/tricycle parts (centre stand and brake pedal) using AFS guidelines. The scraps' chemical compositions were analysed. Thereafter, some mechanical properties with the microstructure of the aluminium casts and that of commercially obtained imported types were examined using appropriate ASTM standards. Cast aluminium alloy produced using scrap had no casting defects and had some mechanical properties comparable to those available on the markets (imported). Thus, effective usage of naturally available moulding sands in Nigeria for foundry applications would help to proffer sustainable solutions to the nation's economic problem as a result of the adverse effects of the Covid-19 pandemic. [ABSTRACT FROM AUTHOR]

The ablation casting technology consists in pouring castings in single-use moulds made from the mixture of sand and watersoluble binder. After pouring the mould with liquid metal the mould is destructed (washed out) using a stream of cooling medium, which in this case is water. The process takes place while the casting is still solidifying. The following paper focuses on testing the influence of the modified ablation casting of aluminum alloy on casts properties produced in moulds with hydrated sodium silicate binder. The authors showed that the best kind of moulding sands for Al alloy casting will be those hardened with physical factors - through dehydration. The analysis of literature data and own research have shown that the moulding sand with hydrated sodium silicate hardened by dehydration is characterized by sufficient strength properties for the modified ablation casting of Al alloys. In the paper the use of microwave hardened moulding sands has been proposed. The moulds were prepared in the matrix specially designed for this technology. Two castings from the AlSi7Mg alloy were made; one by traditional gravity casting and the other by gravity casting using ablation. The conducted casts tests showed that the casting made in modified ablation casting technology characterizes by higher mechanical properties than the casting made in traditional casting technology. In both experimental castings the directional solidification was observed, however in casting made by ablation casting, dimensions of dendrites in the structure at appropriate levels were smaller. [ABSTRACT FROM AUTHOR]

The paper presents the results of laboratory tests into the effects of moisture and the content of two types of bentonite on dielectric properties of moulding sand. The use of electromagnetic waves in foundry industry is becoming more and more popular, which provides to some extent alternatives to conventional drying methods. Experimental studies published so far have shown the validity of using microwaves for drying classic moulding sands with bentonite. However, these studies lack data on the effect of moisture or bentonite content in moulding sand on the real component ε' or imaginary component ε'' of the relative complex electrical permittivity. The presented results may become in the future the basis for the evaluation of the composition of moulding sands, taking into account the phenomena occurring under the influence of electromagnetic field, which directly translates into the quality of the castings made and may constitute an attempt to develop a mathematical model of electric properties of moulding sands. [ABSTRACT FROM AUTHOR]

Increased application of organic compounds, mainly in form of synthetic resins, used as binders for moulding and core sands in metal casting, may have an adverse effect on the environment and work conditions in foundry plants. In this article we focused on the identification of the degradation products formed during laboratory scale simulation of complex thermal degradation of commercial binder. For our investigation we have chosen the phenol-formaldehyde based resin hardened by a mixture of organic esters (PFRE) as it is widely used in the core and mould sand technology. The identified degradation products obtained during the experiments varied depending on mechanism used for pyrolysis. In the “slow” evaluation, simple compounds such as: CO, CO 2 , NH 3 , H 2 O, phenol and CH 4 were generated. Meanwhile, during the “flash” pyrolysis (500, 700, 900 and 1100 °C), mainly phenol and its methyl and ethyl derivatives as well as benzene were released. It was determined that the pyrolysis products and their ratio depended on the temperature during the degradation process. [ABSTRACT FROM AUTHOR]

The results of own studies concerning the application of a new additive to the CO2-hardened sodium water glass foundry sands are presented. The new additive, which is a composition of aqueous solutions of modified polyalcohols, has been designated by the symbol "B" and is used as an agent improving the sand knocking out properties. The scope of studies included various mechanical and technological properties of foundry sand mixtures, such as permeability, friability, life cycle of cores and knocking out properties. Two types of water glass with different values of the silica modulus and density, designated as R145 and R150, were tested. Moulding sands used in the tests were made with the additive "B". For comparison, a reference sand mixture with water glass but without the additive "B" was also prepared. [ABSTRACT FROM AUTHOR]

The presented basic research was aimed at determining a correlation between compaction degree of moulding sand and its permittivity εr at 2,45.109 s-1. The measurement results make a basis for mathematical description of a multilayer technological system as is a combination of moulding sand and foundry instrumentation. Analysis of the results shows that compaction significantly influences permittivity of the sandmix containing water-glass, because permittivity value increases with increasing compaction degree. [ABSTRACT FROM AUTHOR]

Out of moulding sands used in the foundry industry, sands with organic binders deserve a special attention. These binders are based on synthetic resins, which ensure obtaining the proper technological properties and sound castings, however, they negatively influence the environment. These resins in their initial state these resins are not very dangerous for people and for the environment, thus under an influence of high temperatures they generate very harmful products, being the result of their thermal decomposition. Depending on the kind of the applied resin, under an influence of a temperature such compounds as: furfuryl alcohol, formaldehyde, phenol, BTEX group (benzene, toluene, ethylbenzene, xylene), and also polycyclic aromatic hydrocarbons (PAHs) can be formed and released. The aim of the study was the development of the method, selection of analytical methods and the determination of optimal conditions of formation compounds from the BTEX and PAHs group. Investigations were carried out in the specially designed set up for the thermal decomposition of organic substances in a temperature range: 500 - 1 300°C at the laboratory scale. The object for testing was alkyd resin applied as a binding material for moulding sands. The qualitative and quantitative analyses of compounds were performed by means of the gas chromatography coupled with the mass spectrometry (GC/MS). [ABSTRACT FROM AUTHOR]

The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" activation of inorganic binder in waste moulding sand mixtures physically hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the following cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermally loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermally treated inorganic binder, each of the examined processes employed the surface phenomenon usually associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclically prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the refreshed moulding sands allows them to be reused for manufacture of next moulds. Thus, the two proposed methods for cyclically processing used moulding sands containing sodium silicate, subject to microwave hardening, are suitable for economic and ecological circulation moulding mixtures. [ABSTRACT FROM AUTHOR]

Polysaccharides constitute a wide group of important polymers with many commercial applications, for example food packaging, fibres, coatings, adhesives etc. This review is devoted to the presentation of polysaccharide application in foundry industry. In this paper the selected properties of foundry moulding sand and core sand containing modified polysaccharides as binders are presented according to foreign literature data. Also, author's own research about effect of using moulding sand binder consisting of modified polysaccharide (modified starch) or its composition with non-toxic synthetic polymers are discussed. Based on technologies taken under consideration in this paper, it could be concluded that polysaccharides are suitable as an alternative for use as binder in foundry moulding applications. [ABSTRACT FROM AUTHOR]

The influence of the use of moulding sand with furan resin, prepared both with fresh sand and reclaimed matrix, on the formation of a flake graphite formation at the surface layer of ductile iron castings has been investigated. A series of experimental heats of ductile iron cast in moulds made of moulding sand characterised by different levels of surface active elements (sulphur, oxygen) were performed. The effect of the wall thickness and the initial temperature of the metal in the mould cavity on the formation of flake graphite in the surface layer of the casting is shown in the paper. Investigations carried out by means of scanning electron microscopy (energy dispersive X-ray spectroscopy and wavelength dispersive X-ray spectroscopy) showed concentration of gradient profiles of surface active elements in the castings surface layer, which are responsible for their quality. Finally, it has been shown that there exists a significant effect of the quality of the sand on the formation of the flake graphite layer and the surface characteristics of ductile iron castings. [ABSTRACT FROM AUTHOR]

The results of preliminary tests of selected properties of the moulding sands with the binder in the form of a 5 % water solution of the sodium salt of carboxymethyl starch (with a degree of substitution (DS) of 0,2 and 0,87) are presented in this study. The moulding sand properties such as permeability, abrasion resistance, tensile and bending strength - after curing - are shown in series of tests. The cure process was conducted in a field of electromagnetic radiation within the microwave range. The effect of the microwave treatment on the moulding sand was evaporating of water (solvent in a binder) and cross-linking of the polymeric binder. Asa result the cured moulding sands with particular properties, essential in the context of its application in the mould technology in the foundry industry, were obtained. [ABSTRACT FROM AUTHOR]

The article contains the results of emission BTEX (benzene, toluene, ethylobenzene and xylenes) during thermal destruction (500 - 1 300 °C) of moulding sand with furan resin. This furan resin is with a high content of free furfuryl alcohol (about 80 %). Knowledge of emissions of these compounds allows the assessment the harmfulness of a given moulding sand. Quantitative analysis of BTEX is highly complex and requires using of modern equipment (e.g. gas chromatography -- mass spectrometry). Therefore, an attempt to assess potential emissions of BTEX compounds from a given moulding sand based on measurements of total volatile organic compounds (VOC) emission and loss on ignition (LOI). These measurements are less time-consuming and do not require expensive equipment. [ABSTRACT FROM AUTHOR]

The paper presents results of a research on a possibility to apply the innovative, combined with activation of the binder, reclamation process of microwave-hardened moulding sands containing water-glass. The sandmix to be examined, prepared of high-silica sand and the selected water-glass grade 145, was subject to the following cyclical processing stages: mixing the components, compacting, microwave hardening, cooling-down, thermal loading the mould to 800 or 1200 °C, cooling-down to ambient temperature, knocking-out, mechanical dry and wet reclamation, refreshing. After each subsequent cycle of processing the sandmix, used and overheated to various degrees, determined was tensile and bending strength. Analysis of the obtained results indicates that it is possible to activate regenerate of used sandmix containing water-glass, hardened by microwave heating. However, effectiveness of activation in subsequent life cycles of the sandmix is significantly affected by temperature of the casting alloy poured to the mould. [ABSTRACT FROM AUTHOR]

This paper focuses on the possibility of using the biodegradable materials as binders (or parts of binders' compositions) for foundry moulding and core sands. Results showed that there is a great possibility of using available biodegradable materials as foundry moulding sand binders. Using biodegradable materials as partial content of new binders, or additives to moulding sands may not only decrease the toxicity and increase reclamation ability of tested moulding sands, but also accelerate the biodegradation rate of used binders, and the new biodegradable additive (PCL) did not decrease the strength and thermal properties. In addition, using polycaprolactone (PCL) as a biodegradable material may improve the flexibility of moulding sands with polymeric binder and reduce toxicity. [ABSTRACT FROM AUTHOR]

The article discusses the issue of the influence of colloidal solutions of nanoparticles of ZnO obtained using original method on physical and chemical properties (cohesions, adhesion, wettability) of water glass. Adhesion and cohesion strength has been determined on the basis of own methodology of measurement using a special apparatus. The results of the above measurements have been supplemented with selected measurements of quartz wettability by the modified binder. Also, exemplary results have been presented of tests involving basic properties of moulding sans containing an addition of the aforementioned binder. In conclusions, the influence of binder modification on the properties of moulding sands have been presented. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate the development of microstructure and variations in chemical composition in commercial Inconel 625 coatings on a ferritic-pearlitic steel overlaid by the CMT method. The investigation showed that microsegregation occurring during the weld overlay solidification makes the dendrite cores to be richer in Ni, Fe and Cr and in the between dendrite arms in Mo and Nb. Niobium shows the strongest tendency to segregation during solidification; molybdenum tends to segregate less and chromium has the lowest tendency to segregation. Although Inconel 625 is a solid solution strengthened alloy, Nb and Mo-rich phases are formed in the between dendrite arms of weld overlays. [ABSTRACT FROM AUTHOR]

One main problem in moulding is the proper characterization of the local density of the mould, the best without its destroying, for assessment the quality of the mould and to compare results of compaction modeling with experimental results. Industrial computer tomography (ICT) is a technique that allows the non-destructive and contact-free visualization and characterization of the internal and external parts of physical objects including also sand moulds. It is possible to apply ICT technique for the specific research presented here. Moulding sand compaction plays an important role for the quality of the mould and as the consequence for the quality of manufactured casting. The required quality of the castings can be achieved by selecting optimum manufacturing process parameters. The determination of these parameters is often carried out by trial-and-error-method, which is expensive and time consuming. To improve the understanding of the influence of various parameters, mathematical modeling of the compaction processes using numerical solutions was performed. Theoretical results of the compaction simulations have then been compared with practical results of mould compaction obtained by ICT. Itwasfound that simulation results agree well with data from computer tomography and provide insight into the spatial distribution of the density of sand moulds under industrial condition. [ABSTRACT FROM AUTHOR]

The necessity of receiving high quality castings forces undertaking research to elaborate moulding and core sands ensuring obtaining the materials with relevant technological parameters and also with high environmental standards. The most important group here are moulding sands with hydrated sodium silicate. Unfortunately, their fundamental disadvantages are weak knock-out properties. The article presents the most commonly used methods of measuring the knock-out properties of moulding and core sands. The authors propose a new method for estimation this parameter. The method is based on the measurement of high-temperature expansion. [ABSTRACT FROM AUTHOR]

The quality of moulding sand used in foundry usually exerts significant influence on cast properties. It is therefore imperative that the moulding characteristics of a green sand deposit are established prior to its application. This work compares the foundry properties of moulding sand from River Osun and Saki with a view to determining their suitability for casting household utensils. In addition, it also investigated the effect of termite hill activities on moulding sand. Samples of the sands were obtained from different locations within the deposits in Oshogbo and Saki respectively. AFS sieve analysis was performed on the sand to obtain 600 μm grain sizes. These compositions were later mixed in different proportions and then subjected to green and dry compression strengths, shatter index, permeability and moisture content tests. The results obtained indicated that Oshogbo sand deposit has superior green and dry compression strengths values of 16.35 kN/m2 and 14.49 kN/m2 over that of Saki which exhibited 9.3 kN/m2 and 8.3 kN/m2 respectively. The highest permeability of 193 ml/min was demonstrated by Saki compared with 79 ml/min by Oshogbo deposits while the difference in their moisture contents is insignificant. The shatter index of 64 % and 72 % was obtained for Oshogbo and Saki sands respectively. These results demonstrated the possible utility of both sands for making of sand casting moulds. However, Oshogbo deposit is recommended for its higher fraction of the 600μm grain being the preferred size with demonstrable foundry sand desired properties. [ABSTRACT FROM AUTHOR]

Reclamation of used moulding and core sands has been defined as a treatment of waste moulding refractory materials, enabling a recovery of at least one of the components having properties similar to those ofthe fresh component, and reuse for production of casting moulds and cores. However, at present, there is a lackof a reclaimed material assessment index, which could be applied to each type of moulding sand and reclaim. Modern investigation methods and equipment for the estimation of the quality of the moulding sands matrices with organic binders, in their circulation process, are presented in this paper. These methods, utilizing the special equipment combined with the author's investigation methods developed in the Faculty of Foundry Engineering, AGH - University of Science and Technology, allow the better estimation of the matrix quality both in an aspectof its application as a fresh sand substitute in the preparation of moulding sands, and also with regard to the environmental protection. The most important criteria for the technological assessment of the reclaimed materials and the quality of sands with organic binders are presented in this paper. [ABSTRACT FROM AUTHOR]

The paper presents a semi-industrial reactor designed for microwave utilization of waste moulds and cores made of moulding sands prepared infurane resin technology. It was found that a possibility exists of effective incinerating this way prepared residues of cores separated from moulding sands or waste moulds left after casting. The preliminary tests evidenced that microwave heating is an effective way of disposing waste moulding sands and the applied apparatus permits effective control of the microwave heating process. [ABSTRACT FROM AUTHOR]

The paper presents results of preliminary examinations of possibility to measure binder content in traditional moulding sands using a new method employing electromagnetic waves. The presented examinations were carried-out with use of an innovative test station, the so-called microwave slot line. The measurements of binder content in moulding sand were based on the results of power balance investigation of microwaves affecting the specimen. An advantage of the suggested, new method of binder content measurement is short measuring time. [ABSTRACT FROM AUTHOR]

The subject-matter of the paper covers a very topical problem of possible restriction of shortcomings like poor knocking-out properties of castings and hard reclaimability of this type sandmixes by proper selecting their components and using innovative microwave heating. It was proved that the sandmixes subject to quick dielectric process of drying/hardening show significantly lower residual strength, which gives this method priority over traditional energy-consuming processes of casting core manufacture. [ABSTRACT FROM AUTHOR]

Procedures have been developed to determine the volume, rate and composition (particularly BTEX: benzene, toluene, ethylbenzene and xylenes and PAHs (polycyclic aromatic hydrocarbons)) of gas evolution from moulds and cores prepared with various binders as a means of harmfulness of moulding sands. The rate of gas evolution from green sands with four different lustrous carbon carrier and BTEX content were determined. The gas evolution rates are highest in the range of about 20 to 30 s after contact with molten metal. In practice during the first 200-250 s the total emission of gases generated in investigated samples occurred. The main emitted component from the BTEX group was benzene. [ABSTRACT FROM AUTHOR]

Proper sand management and efficient sand reclamation system are two main factors influencing economical and ecological side of modern foundry plant. It is well known fact that the production of 1 metric ton of casting from ferrous alloys generates circa 1 metric ton of waste [1], which due to containing certain amounts of harmful and dangerous compounds should undergo a reclamation -- at least of the main component, which means a silica sand grains. The paper present problems of scientific and development research concerning the innovative reclamation technologies of used foundry sands such as: mechanical-cryogenic reclamation and innovative thermal reclamation. [ABSTRACT FROM AUTHOR]

The paper presents examination results on possible implementing an innovative microwave technology for manufacture of high-quality, economic cores of water-glass moulding sands. A special attention was paid to improving technological properties of the examined moulding sands and in particular of their strength and knocking-out properties by selecting proper parameters of the hardening process. In addition, some benefits are indicated, resulting from applying such an innovative and environment-friendly solution effectively replacing traditional and energy-consuming processes of preparing moulding cores. [ABSTRACT FROM AUTHOR]

The aim of this article is to test the properties of foundry moulding sands with a new bicomponent organic binder. The new binder is the composition of phenol-furfuryl resin, commonly used in foundry practice and biodegradable material - polycaprolactone. The paper presents the research of strength properties, thermal destruction and thermal deformation of moulding sands with a new bicomponent binder. It was proved that inserting polycaprolactone to phenol-furfuryl resin did not lower the strength properties of tested moulding sands. The new additive did not affect the moulding sands thermal degradation but it changed their thermal deformation course. [ABSTRACT FROM AUTHOR]

The aim of this article is to show the possibility of using biodegradable materials as part of the composition of foundry moulding and core sand binders. Research shows that moulding sands with biodegradable materials selected as binders are not only less toxic but are also better suited to mechanical reclamation than moulding sands with phenol-furfuryl resin. The use of biodegradable materials as additives to typical synthetic resins can result in their decreased toxicity and improved ability to reclamation as well as in accelerated biodegradation of binding material leftovers of mechanical reclamation. [ABSTRACT FROM AUTHOR]

The article presents the results of research aimed at examining the type of swelling material introduced into moulding or core sand to improve their knock-out properties. Tests on Slovak perlite ore (three grain sizes), Hungarian perlite ore and ground vermiculite (South Africa) were carried out. For this purpose, thermal and structural analyses (FTIR—Fourier Transform Infrared Spectroscopy), a chemical composition test (XRF-X-Ray Fluorescence), phase analysis (XRD—X-Ray Diffraction), and scanning electron microscopy (SEM—Scanning Electron Microscope) as well as final strength tests of moulding sands with the addition of perlite ore and vermiculite were carried out. The results of thermal studies were related to IR (Infrared Spectroscopy) spectra and XRD diffractograms. It has been shown that the water content in the pearlite ore is almost three times lower than in vermiculite, but the process of its removal is different. Moreover, the chemical composition of the perlite ore, in particular the alkali content and its grain size, may influence its structure. The phenomena of expansion (perlite) and peeling (vermiculite) have a positive effect on the reduction of the final sand strength and eliminate technological inconveniences (poor knocking out) that significantly limit the wide use of moulding sands with inorganic binders. [ABSTRACT FROM AUTHOR]