Possibilities of Reclamation Microwave-Hardened Molding Sands with Water Glass

Stachowicz, M.; Granat, K.

doi:10.2478/amm-2014-0127

Cited by 17 publications

(22 citation statements)

References 4 publications

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“…The observed cracking can be considered undesirable and unfavourable from the viewpoint of further utilisation of high-silica base, e.g. at cyclical refreshing of moulding sands containing water-glass [13,14]. Except the precipitates visible in vicinity of linking bridges after traditional drying, no differences were observed in their structures that could explain various mechanical parameters (Fig.…”

Section: Resultsmentioning

confidence: 99%

Effect of Sand Wetting on Physically Hardened Moulding Sands Containing a Selected Inorganic Binder. Part 2

Stachowicz¹,

Granat²,

Pałyga³

2016

Archives of Foundry Engineering

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In the paper, an attempt is made to explain the previously observed increased effectiveness of utilising hydrated sodium water-glass grade 137 after hardening moulding sands with selected physical methods. In the modified process of preparing sandmixes, during stirring components, water as a wetting additive was introduced to the sand-binder system. Presented are examination results of influence of faster microwave heating and slower traditional drying of the so-prepared moulding sands on their tensile and bending strength, calculated per weight fraction of the binder. The measurement results were confronted with SEM observations of linking bridges and with chemical analyses of grain surfaces of high-silica base. On the grounds of comprehensive evaluation of hardened moulding sands, positive effects were found of the applied physical process of binder dehydration and presence of the wetting additive. It was observed that introduction of this additive during stirring, before adding the binder, improves flowing the binder to the places where durable linking bridges are created. It was also found that the applied methods of hardening by dehydration enable creation of very durable linking bridges, strongly connected with the sand base, which results in damages of high-silica grain surfaces, when the bridges are destroyed.

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Section: Resultsmentioning

confidence: 99%

Effect of Sand Wetting on Physically Hardened Moulding Sands Containing a Selected Inorganic Binder. Part 2

Stachowicz¹,

Granat²,

Pałyga³

2016

Archives of Foundry Engineering

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“…This is certainly related to the accelerated process of microwave heating of moulding sand (base sand, water supporting microwave absorption and hydrated sodium silicate) [17]. In the case of bonding bridges created during microwave heating, destruction caused by the applied tensile load proceeded, first of all, in the material of sodium silicate film, and so in the cohesive way.…”

Section: Effect Of Hardening Methods On Structure Of Bonding Bridgesmentioning

confidence: 99%

“…Results of own research works [15][16][17] have inspired us to continue evaluation of chromite sand as prospective base of moulding sands that could be used as eco-friendly and economical moulding sands, possibly also as circulating foundry materials.…”

Section: Objective Of the Researchmentioning

confidence: 99%

Influence of sand base preparation on properties of chromite moulding sands with sodium silicate hardened with selected methods

Stachowicz

Granat

Pałyga

2017

Archives of Metallurgy and Materials

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The paper presents a research on the relation between thermal preparation of chromite sand base of moulding sands containing sodium silicate, hardened with selected physical and chemical methods, and structure of the created bonding bridges. Test specimens were prepared of chromite sand -fresh or baked at 950°C for 10 or 24 hours -mixed with 0.5 wt.% of the selected non-modified inorganic binder and, after forming, were hardened with CO 2 or liquid esters, dried traditionally or heated with microwaves at 2.45 GHz. It was shown on the grounds of SEM observations that the time of baking the base sand and the hardening method significantly affect structure of the bonding bridges and are correlated with mechanical properties of the moulding sands. It was found that hardening chromite-based moulding mixtures with physical methods is much more favourable than hardening with chemical methods, guaranteeing also more than ten times higher mechanical properties.

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“…The results should be helpful at determining directions of further research works on microwave heating of chromite-based moulding sands, with particular consideration of running the activation process similarly as for quartz-based sandmixes with water-glass [7].…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature on Chromite-Based Moulding Sands Bonded with Sodium Silicate

Stachowicz¹,

Kamiński²,

Granat³

et al. 2016

Archives of Foundry Engineering

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In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within 100 to 1200 °C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.

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Possibilities of Reclamation Microwave-Hardened Molding Sands with Water Glass

Cited by 17 publications

References 4 publications

Effect of Sand Wetting on Physically Hardened Moulding Sands Containing a Selected Inorganic Binder. Part 2

Effect of Sand Wetting on Physically Hardened Moulding Sands Containing a Selected Inorganic Binder. Part 2

Influence of sand base preparation on properties of chromite moulding sands with sodium silicate hardened with selected methods

Effect of Temperature on Chromite-Based Moulding Sands Bonded with Sodium Silicate

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