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1
Content available Effect of Methyl Silicone Oil to Moisture Resistance of Sodium Silicate Sands by Microwave Hardening
Wang Huafang, Gao Xiang, Yang Lei, He Wei, Lu Jijun
Archives of Foundry Engineering
|
2022
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Vol. 22, iss. 1
43--47
EN
The sodium silicate sands hardened by microwave have the advantages of high strength, fast hardening speed and low residual strength with the lower addition of sodium silicate. However, the sodium ion in the sands will absorb moisture from the atmosphere, which would lead to lower storing strength, so the protection of a bonding bridge of sodium silicate between the sands is crucial. Methyl silicone oil is a cheap hydrophobic industrial raw material. The influence of the addition amount of methyl silicone oil modifier on compressive strength and moisture absorption of sodium silicate sands was studied in this work. The microscopic analysis of modified before and after sodium silicate sands has been carried on employing scanning electron microscopy(SEM) and energy spectrum analysis(EDS). The results showed that the strength of modified sodium silicate sands was significantly higher than that of unmodified sodium silicate sands, and the best addition of methyl silicone oil in the quantity of sodium silicate was 15%. It was also found that the bonding bridge of modified sodium silicate sands was the density and the adhesive film was smooth, and the methyl silicone oil was completely covered on the surface of the sodium silicate bonding bridge to protect it.
2
Content available The Influence of the Modified Ablation Casting on Casts Properties Produced in Microwave Hardened Moulds with Hydrated Sodium Silicate Binder
Major-Gabryś K., Hosadyna-Kondracka M., Puzio S., Kamińska J., Angrecki M.
Archives of Metallurgy and Materials
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2020
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Vol. 65, iss. 1
497--502
EN
The ablation casting technology consists in pouring castings in single-use moulds made from the mixture of sand and water-soluble 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.
3
Content available Effect of the Type of Inorganic Binder on the Properties of Microwave-Hardened Moulding Sands for Ablation Casting Technology
Puzio S., Kamińska J., Angrecki M., Major-Gabryś K.
Archives of Metallurgy and Materials
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2020
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Vol. 65, iss. 4
1385--1390
EN
The aim of this study is to demonstrate the possibility of using moulding sands based on inorganic binders hardened in a microwave chamber in the technology of ablation casting of aluminium alloys. The essence of the ablation casting technology consists in this that a mould with a water-soluble binder is continuously washed with water immediately after being poured with liquid alloy until its complete erosion takes place. The application of an environmentally friendly inorganic binder improves the ecology of the whole process, while microwave hardening of moulding sands allows moulds to be made from the sand mixture containing only a small amount of binder. The studies described in this article included microwave-hardened sand mixtures containing the addition of selected inorganic binders available on the market. The strength of the sands with selected binders added in an amount of 1.0; 1.5 and 2.0 parts by mass was tested. As a next step, the sand mixtures with the strength optimal for ablation casting technology, i.e. about 1.5 MPa, were selected and tested for the gas forming tendency. In the four selected sand mixtures, changes occurring in the samples during heating were traced. Tests also included mould response to the destructive effect of ablation medium, which consisted in the measurement of time necessary for moulds to disintegrate while washed with water. Tests have shown the possibility of using environmentally friendly, microwave-hardened moulding sands in ablation casting of aluminium alloys.
4
Content available Microwave-Hardened Moulding Sands with Hydrated Sodium Silicate for Modified Ablation Casting
Puzio S., Kamińska J., Major-Gabryś K., Angrecki M., Hosadyna-Kondracka M.
Archives of Foundry Engineering
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2019
|
iss. 2
91--96
EN
The aim of this study is to demonstrate the possibility of using moulds made from the environmentally friendly sands with hydrated sodium silicate in modified ablation casting. The ablation casting technology is primarily intended for castings with diversified wall thickness and complex shapes made in sand moulds. The article presents the effect of binder content and hardening time on the bending strength Rgu of moulding sands with binders based on hydrated sodium silicate hardened by microwave technology. The aim of the research was to develop an optimal sand composition that would provide the strength necessary to make a mould capable of withstanding the modified ablation casting process. At the same time, the sand composition should guarantee the susceptibility of the mould to the destructive action of the ablation medium, which in this case is water. Tests have shown that microwave hardening provides satisfactory moulds’ strength properties even at a low binder content in the sand mixture.
5
Content available Influence of sand base preparation on properties of chromite moulding sands with sodium silicate hardened with selected methods
Stachowicz M., Granat K., Pałyga Ł.
Archives of Metallurgy and Materials
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2017
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Vol. 62, iss. 1
379--383
EN
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 CO2 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.
6
Content available The influence of Glassex additive on properties of microwave-hardened and self-hardened moulding sands with water glass
Major-Gabryś K., Dobosz S. M., Jakubski J., Stachowicz M., Nowak D.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 1
130-134
EN
The article takes into consideration the researches concerning inserting the Glassex additive to the microwaved-hardened and self-hardened moulding sands with water glass. In the research different types of ester hardeners to self-hardened moulding sands with water glass were used. The influence of Glassex additive on retained strength of moulding sands with different hardeners and prepared by different technologies of hardening were tested. The influence of different hardeners and the technology of hardening on retained strength of moulding sand with water glass and the Glassex additive were also estimated.
7
Content available Innovative microwave hardening of water-glass containing sandmixes in technical-economic approach
Małachowska A., Stachowicz M., Granat K.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 1
75-80
EN
In recent years, observed is increasing interest in sandmixes containing inorganic binders. These binders, including also water-glass, are harmless for the environment, neutral for humans and relatively cheap. In spite of numerous advantages, their wide application is restricted by poor knock-out properties and problems related to rebonding. Therefore, numerous researches aimed at eliminating disadvantages of water-glass binder are directed, among others, to modifying structure of hydrated sodium silicate or to applying new hardening techniques. The innovative method of rapid hardening by microwave heating, that permits restricting quantity of used binder and thus improving knock-out properties, meets expectations of present-day foundries. In this paper, compiled is available information on microwave hardening of water-glass containing sandmixes, as well as costs of practical application of this technology are evaluated on the ground of own research.
8
Content available remote Influence of water-glass grade and quantity on residual strength of microwave-hardened moulding sands. Part 2
Stachowicz M., Granat K., Nowak D.
Archives of Foundry Engineering
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2011
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Vol. 11, iss. 2
143-148
EN
The paper continues dealing with the issues of influence of microwave hardening on mechanical properties of waterglass-based moulding sands. This second part of the research includes examining moulding sands containing 1.5, 2.5 and 3.5% of hydrated sodium silicate grade 150. Standardised, microwave-hardened cylindrical specimens for mechanical testing were held at temperatures from 100 to 1200 oC for 30 minutes, cooled-down to ambient temperature and then their residual strength was determined. An attempt was made to explain the effect of microwave hardening on strength of moulding sands as a function of baking temperature, supported by SEM observations of the baked sandmixes. On the grounds of these observations, destruction nature of linking bridges was identified. It was found that the applied microwave hardening is beneficial by reducing residual strength of waterglass-containing moulding sands and thus improving their knockout properties.
9
Content available remote Influence of water-glass grade and quantity on residual strength of microwave-hardened moulding sands. Part 1
Stachowicz M., Granat K., Nowak D.
Archives of Foundry Engineering
|
2011
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Vol. 11, iss. 1
93-98
EN
The paper presents a research on influence of dielectric drying process on mechanical properties of water-glass containing moulding sands. Examined were moulding sands containing additions of 1.5 and 2.5 % of hydrated sodium silicate grades 145, 149 and 150, most often used in foundry practice. Standard, cylindrical specimens for mechanical testing were held at temperatures from 100 to 1200 oC for 30 minutes and next cooled-down to ambient temperature. Then their residual strength was determined. Comparison of the obtained results with literature data indicates that dielectric drying is favourable for reduction of residual strength of used water-glass moulding sands, and thus improves their knock-out properties.
10
Content available Effect of bentonite addition on residual strength of microwave-hardened waterglass-containing moulding sands
Stachowicz M., Granat K., Nowak D.
Archives of Foundry Engineering
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2011
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Vol. 11, iss. 3 spec.
199--204
EN
The paper presents results of a preliminary research of the effect of bentonite addition on residual strength of microwave-hardened moulding sands, containing sodium waterglass. Strength was determined at ambient temperature, on cylindrical specimens baked in an oven. Moulding sands for examinations were based on high-silica sand with addition of 2.5 % of non-modified, domestic-made waterglass grade 145. The prepared standard cylindrical specimens were hardened using the innovative microwave heating process and next baked for 30 minutes at temp eratures between 100 and 1200 °C. Strength parameters of the specimens were determined on the specimens cooled-down to ambient temperature. The obtained results were compared with literature data to evaluate the effect of the applied hardening method and of the special additive on residual strength as a function of baking temperature. A favourable effect was found of both the innovative heating process and the applied bentonite addition.
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