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Effectiveness of Absorbing Microwaves by the Multimaterial Sodium Silicate Base Sand - PLA (Polylactide) Mould Wall Systems

Stachowicz Mateusz

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

30--37

EN

In the paper presented are results of a research on effectiveness of absorbing electromagnetic waves at frequency 2.45 GHz by unhardened sodium silicate base sands (SSBS) prepared of high-silica base sand and a PLA (Polylactide) 3D-prited (3DP) mould walls. Measurements of power loss of microwave radiation (Pin) expressed by a total of absorbed power (Pabs), output power (Pout) and reflected power (Pref) were carried-out on a stand of semiautomatic microwave slot line for determining balance of microwave power emitted into selected multimaterial systems. Values of microwave power loss in the rectangular waveguide filled with unhardened moulding sands and prepared by fused deposition modelling (FDM) 5 mm polylactide (PLA) walls with grid infill density from 25% to c.a. 100% served for determining effectiveness of microwave heating. Balance of microwave power loss is of technological importance for microwave manufacture of high quality casting sand moulds and cores in possibility of use 3D-printed mould tools and core boxes. It was found that apparent density of SSBS placed in a waveguide with PLA walls influences parameters of power output (Pout) and power reflected (Pref). The PLA wall position and grid infill density were identified to have a limited effect on effectiveness of absorbing microwaves (Pabs).

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Study on Reclamation of CO2-hardened Sodium Silicate Used Sands by CaO Powder

Lu Jijun, Yang Lei, Qian Jiangbing, He Wei, Wang Huafang

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 3

99--106

EN

Aiming at the problems of wet reclamation consuming a lot of water, dry (mechanical) reclamation having wear and power consumption, this paper to find suitable reclamation reagents to reduce the influence of harmful substances in used sodium silicate sands. By comparing the reclamation effect of CaO, Ca(OH)2 and Ba(OH)2 reclamation powder reagents, it was concluded that CaO had the best reclamation effect. Through the single factor experiment, the influence of CaO on the reclamation effect was explored: 1. addition amount of CaO; 2. the additional amount of water; 3. reclamation time. The orthogonal results showed that the CaO reclamation effect was the best when the amount of CaO was 1.5%, the amount of sodium silicate was 4.0%, the amount of water added was 6.0%, and the reclamation time was 12.0h. In this experiment, 82.2% carbonate and 75.0 % silicate in used sands can be removed. The microscopic analysis of the reclamation sands was carried out by scanning electron microscope (SEM); The surface was relatively smooth, without large area cracks and powder accumulation. Compared with the used sands, the instant, 24h ultimate, and residual strengths of the reclaimed sands were increased by 536.5%, 458.1%, and 89.8%, respectively, which was beneficial to the reclamation of the CO2 sodium silicate used sands.

3

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

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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.