High-Temperature Wetting Behavior and Adhesion Mechanism of Cryolite-Based Molten Salt on SiC Refractory Substrate
Highlights
- The wetting behaviors of molten aluminum slag droplets on SiC plates in various Al2O3 contents were investigated.
- Al2O3 enhances both surface tensions of the slag, thereby increasing the adhesion work between the slag and SiC.
- Revealing the interfacial microstructure evolution and the interaction mechanism between Na3AlF6-Al2O3-CaF2 slag and SiC.
- Providing a theoretical basis for the guidance of developing, designing, and applying inner wall materials for vacuum ladles.
Abstract
:1. Introduction
2. Experimental and Thermodynamic Calculations
2.1. Preparation of the Aluminum Slag and SiC Substrate
2.2. Experimental Methods and Thermodynamic Simulation Calculations
3. Results and Discussion
3.1. Aluminum Slag Melting and the Change of Droplet Morphology
3.2. The Apparent Contact Angle Between the Molten Slag and the SiC Substrate
3.3. Effect of Al2O3 Content on Surface Tension and Interfacial Properties Between Slag and Silicon Carbide Substrate
3.4. Analysis of the Microstructure and Interfacial Behavior of the Interface Between Slag and Refractory Materials
4. Conclusions
- (1)
- The experimental wetting process is summarized in three stages: melting and wetting, dissolution and diffusion, and crystallization. Two primary factors that influence substrate adhesion are considered: good wettability and the dissolution of Al2O3 in the slag. The interaction between the slag and the SiC substrate is described as non-reactive wetting, and the results demonstrate that the melting temperature of the Na3AlF6-Al2O3-CaF2 slag increases significantly with the addition of Al2O3. This increase in temperature leads to enhanced mobility of the elements within the slag, facilitating improved mass transfer and diffusion of molecules or ions. Furthermore, as the Al2O3 content increases, the contact angle between the cryolite-based molten salt and SiC decreases, reducing the height of the resulting slag layer and gradually increases the wetting radius, thus rendering the slag more effective at wetting and spreading on the substrate.
- (2)
- Theoretical calculations indicate that Al2O3 enhances both surface tensions of the slag, thereby increasing the adhesion work between the slag and SiC. The initial spreading of the slag on the SiC substrate is primarily due to the reduction in the surface tension. The penetration depth of the slag into the SiC substrate gradually increased with increasing Al2O3 content, resulting in more severe penetration into the SiC refractory material. At high temperatures, the liquid slag phase formed within the refractory entered the SiC pores, promoting the penetration of the slag.
- (3)
- In summary, this study provides a comprehensive analysis of the wettability and adhesion mechanisms of aluminum slag on SiC-based refractory materials. Increasing the Al2O3 content in the slag can reduce its wettability on SiC, thereby minimizing slag adherence to the ladle lining. Material Selection: Using SiC-based refractory materials with optimized Al2O3 content can improve the ladle lining’s resistance to slag penetration and mechanical erosion. Surface Treatment: Applying surface treatments or coatings that further reduce the wettability of the slag on SiC can enhance the durability of the ladle lining. These results have important implications for optimizing the design of vacuum ladles and other industrial equipment used in aluminum electrolysis. While our study provides valuable insights into the interactions between aluminum slag and SiC-based refractory materials, several avenues for future research remain. For instance, further investigations could explore the effects of other slag components, such as CaF2 and Na3AlF6, on wetting and adhesion behavior. Additionally, the impact of operational parameters, such as temperature and applied voltage, on these interactions can be studied in more detail. Long-term durability tests under realistic industrial conditions would also be beneficial for assessing the performance of optimized refractory materials over an extended period.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
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Chemical | Specification |
---|---|
Na3AlF6 | ≤0.2% |
Al2O3 | 94 HRA |
CaF2 | 0.14 |
Sample Slag | Na3AlF6 | Al2O3 | CaF2 |
---|---|---|---|
1# | 95 | 0 | 5 |
2# | 90 | 5 | 5 |
3# | 85 | 10 | 5 |
4# | 80 | 15 | 5 |
5# | 75 | 20 | 5 |
Component | SiC | SiO | Fe2O3 | Free Silicon Content |
---|---|---|---|---|
Content/mass% | 99.45 | 0.02 | 0.01 | ≤0.1 |
Properties | Silicon Carbide Substrate |
---|---|
Apparent porosity | ≤0.2% |
Rockwell hardness | 94 HRA |
Poisson’s ratio | 0.14 |
Chemical | Surface Tension (mN/m) |
---|---|
Na3AlF6 | 273.74–0.138 T |
Al2O3 | 1024–0.177 T |
CaF2 | 442.4–0.0816 T |
Sample | Point | Element Content/wt% | ||||||
---|---|---|---|---|---|---|---|---|
C | O | F | Na | Al | Si | Ca | ||
5 | 22 | 41.47 | 4.81 | 0.31 | 0.34 | 0.34 | 52.61 | 0.12 |
23 | 34.11 | 1.16 | 0.16 | 0.09 | 0 | 64.48 | 0 | |
24 | 48.22 | 23.24 | 1.43 | 2.93 | 7.88 | 15.13 | 1.17 | |
25 | 66.05 | 1.3 | 0.04 | 0.11 | 0 | 32.42 | 0.08 | |
26 | 37.54 | 1.22 | 0.17 | 0 | 0 | 61.03 | 0.03 | |
27 | 33.3 | 30.19 | 0.49 | 8.61 | 12.64 | 13.66 | 1.12 | |
20 | 13 | 49.38 | 1.84 | 0.04 | 0 | 0 | 48.69 | 0.05 |
14 | 35.24 | 1.29 | 0.09 | 0.01 | 0 | 63.37 | 0 | |
15 | 36.32 | 2.34 | 0.11 | 0.04 | 0 | 61.08 | 0.1 | |
16 | 29.74 | 1.73 | 0.19 | 0.06 | 0 | 68.1 | 0.19 | |
18 | 76.01 | 8.86 | 0.43 | 0.17 | 0 | 14.1 | 0.43 | |
19 | 50 | 1.88 | 0.09 | 0 | 0 | 47.95 | 0.08 | |
20 | 11.17 | 42.93 | 0.06 | 12.31 | 13.76 | 19.68 | 0.1 |
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Feng, Y.; Cheng, W.; Rui, Z.; Sun, H.; Lyu, X.; Dong, Y. High-Temperature Wetting Behavior and Adhesion Mechanism of Cryolite-Based Molten Salt on SiC Refractory Substrate. Materials 2025, 18, 1428. https://doi.org/10.3390/ma18071428
Feng Y, Cheng W, Rui Z, Sun H, Lyu X, Dong Y. High-Temperature Wetting Behavior and Adhesion Mechanism of Cryolite-Based Molten Salt on SiC Refractory Substrate. Materials. 2025; 18(7):1428. https://doi.org/10.3390/ma18071428
Chicago/Turabian StyleFeng, Yuxi, Wandong Cheng, Zhiyuan Rui, Haobo Sun, Xin Lyu, and Yun Dong. 2025. "High-Temperature Wetting Behavior and Adhesion Mechanism of Cryolite-Based Molten Salt on SiC Refractory Substrate" Materials 18, no. 7: 1428. https://doi.org/10.3390/ma18071428
APA StyleFeng, Y., Cheng, W., Rui, Z., Sun, H., Lyu, X., & Dong, Y. (2025). High-Temperature Wetting Behavior and Adhesion Mechanism of Cryolite-Based Molten Salt on SiC Refractory Substrate. Materials, 18(7), 1428. https://doi.org/10.3390/ma18071428