Effects of B2O3 on Viscosity, Structure, and Crystallization of Mold Fluxes for Casting Rare Earth Alloyed Steels
Abstract
:1. Introduction
2. Materials and Methods
2.1. Experimental Slags
2.2. The Viscosity Test
2.3. The Structure Test
2.4. The Crystallization Test
3. Results and Discussion
3.1. Effect of B2O3 Content on Viscosity
3.2. The Effect of B2O3 Content on Structure
3.3. Effect of B2O3 Content on Crystallization
4. Conclusions
- When B2O3 increased from 3 to 10 wt.%, the viscosity and the activation energy of mold fluxes decreased continuously at each temperature, which is beneficial to mold fluxes for casting rare earth alloyed heavy railway steels. According to the requirement of a viscosity value of 0.5 Pa·s at 1300 °C, the reasonable amount of additive B2O3 in mold fluxes is 10 wt.%.
- B2O3 played the role of network former in melts, but decreased the viscosity due to the introduction of B–O with weak bond energy and the structural units transition from four-fold coordination boron to threefold coordination boron with loose structure.
- B2O3 decreased the crystallization ability and the melting point by decreasing the crystallization temperature and the solidus temperature of mold fluxes during the heating process. The increase of B2O3 was beneficial to the crystallization of Ca2B2O5, but not Na4Ca4(Si6O18) during the heating process of mold fluxes.
Author Contributions
Funding
Conflicts of Interest
References
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Sample Number | Composition (wt.%) | ||||||
---|---|---|---|---|---|---|---|
- | CaO | SiO2 | Al2O3 | Na2O | B2O3 | CeO2 | |
1 | Calculated | 27.44 | 41.46 | 7.02 | 13.33 | 3.00 | 7.75 |
Analyzed | 29.77 | 40.50 | 6.58 | 12.58 | 2.81 | 7.76 | |
2 | Calculated | 26.87 | 40.60 | 6.88 | 13.05 | 5.00 | 7.60 |
Analyzed | 29.16 | 39.71 | 6.68 | 12.30 | 4.63 | 7.52 | |
3 | Calculated | 26.31 | 39.75 | 6.73 | 12.78 | 7.00 | 7.43 |
Analyzed | 28.58 | 38.67 | 6.48 | 11.98 | 6.82 | 7.47 | |
4 | Calculated | 25.46 | 38.46 | 6.52 | 12.36 | 10.00 | 7.20 |
Analyzed | 27.88 | 37.24 | 6.22 | 11.66 | 9.87 | 7.13 |
Sample Number | 1 | 2 | 3 | 4 |
---|---|---|---|---|
Ea (KJ/mol) | 166.5 ± 2.7 | 152.4 ± 3.8 | 139.9 ± 4.4 | 142.0 ± 4.0 |
Samples | Tx | Ts |
---|---|---|
1 | 785 | 911 |
2 | 780 | 895 |
3 | 776 | 885 |
4 | 779 | 876 |
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Cai, Z.; Song, B.; Li, L.; Liu, Z.; Cui, X. Effects of B2O3 on Viscosity, Structure, and Crystallization of Mold Fluxes for Casting Rare Earth Alloyed Steels. Metals 2018, 8, 737. https://doi.org/10.3390/met8100737
Cai Z, Song B, Li L, Liu Z, Cui X. Effects of B2O3 on Viscosity, Structure, and Crystallization of Mold Fluxes for Casting Rare Earth Alloyed Steels. Metals. 2018; 8(10):737. https://doi.org/10.3390/met8100737
Chicago/Turabian StyleCai, Zeyun, Bo Song, Longfei Li, Zhen Liu, and Xiaokang Cui. 2018. "Effects of B2O3 on Viscosity, Structure, and Crystallization of Mold Fluxes for Casting Rare Earth Alloyed Steels" Metals 8, no. 10: 737. https://doi.org/10.3390/met8100737