Al<sub>2</sub>O<sub>3</sub>對超高堿度連鑄保護渣理化性能的影響

李剛; 潘偉杰; 李民; 朱禮龍; 何生平

doi:10.13374/j.issn2095-9389.2021.09.07.003

Al₂O₃對超高堿度連鑄保護渣理化性能的影響

doi: 10.13374/j.issn2095-9389.2021.09.07.003

1.
重慶大學材料科學工程學院，重慶 400044
2.
重慶科技學院，重慶 401331

基金項目: 國家自然科學基金面上資助項目（51874057，52074054）；重慶市自然科學基金資助項目（stc2020jcyj-msxmX0605）

詳細信息

通訊作者:
E-mail: heshp@cqu.edu.cn

中圖分類號: TG142.71
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出版歷程
- 收稿日期: 2021-09-07
- 網絡出版日期: 2022-01-20
- 刊出日期: 2023-02-01

Effect of Al₂O₃ on the physical and chemical properties of ultrahigh-basicity continuous casting mold flux

1.
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
2.
Chongqing University of Science and Technology, Chongqing 401331, China

More Information

Corresponding author: E-mail: heshp@cqu.edu.cn

摘要

摘要: Al₂O₃是一種兩性氧化物，在高堿度條件下呈現酸性氧化物特征，而在低堿度條件下表現出堿性氧化物的行為，是冶金熔渣中常見的一種組元。以超高堿度保護渣（綜合堿度R=1.75）為研究對象，分析了Al₂O₃對保護渣流動特性、熔化特性和凝固特性的影響規律。研究結果顯示：渣中Al₂O₃質量分數每增加1%，熔化溫度上升5 ℃左右，轉折溫度下降12 ℃左右，開始結晶溫度平均下降11 ℃左右。平均結晶速率隨渣中Al₂O₃質量分數的增加而減小。且隨著Al₂O₃質量分數的增加，保護渣結晶礦相中晶體比例逐漸降低，但晶體保持槍晶石的種類不變。
- Al₂O₃ /
- 保護渣 /
- 超高堿度 /
- 凝固特性 /
- 結晶性能
Abstract: Aluminum oxide is a common component in mold powder and is a kind of amphoteric oxide. It shows the characteristics of acid oxide under high-alkalinity conditions and of alkaline oxide under low-alkalinity conditions. In general, adding Al₂O₃ to the traditional CaO–SiO₂-based mold flux will increase the viscosity and melting point of the mold flux, which will consequently reduce the mold flux’s ability to adsorb inclusions. In addition, as the content of Al₂O₃ in the slag increases, the solidification temperature of the slag can be reduced, thereby improving the lubricating ability of the mold flux. At present, the research on the crystallization performance of Al₂O₃ on mold fluxes mainly focuses on low-reactivity or non-reactive mold fluxes for high-aluminum steel and high-titanium steel. Relevant studies have shown that Al₂O₃ in low-reactivity or non-reactive mold fluxes can increase the crystallization incubation time of the mold flux, reduce the critical cooling rate of the flux, and inhibit the crystallization process of the flux. In mold powder with low to medium alkalinity content (R = 1.2–1.5) or new CaO–Al₂O₃-based low-reactivity mold powder, the addition of Al₂O₃ will increase the viscosity of the slag and melting point and decrease (or increase) the solidification temperature and crystallization performance. In recent years, ultrahigh-alkalinity mold powder (R = 1.65–1.85) has been successfully applied in peritectic steel continuous casting mold powder, effectively coordinating the contradiction between the mold powder heat transfer and lubrication function. However, there is no relevant report on the influence of Al₂O₃ on the performance of mold flux under ultrahigh-alkalinity conditions. In this study, an ultra-high-alkalinity mold flux (comprehensive alkalinity R = 1.75) is taken as the research object, and the influence of Al₂O₃ on the flow, melting, and solidification characteristics of the mold flux is analyzed. The research results show that as Al₂O₃ increases, the viscosity and melting temperature increase, and the transition temperature decreases. Particularly, with an average increase of 1% Al₂O₃, the melting temperature of the mold flux will increase by approximately 5 ℃, and the turning temperature will decrease by approximately 12 ℃. In addition, as the Al₂O₃ content in the slag increases by 1%, the starting crystallization temperature drops by approximately 11 °C on average. The average crystallization rate decreases with the increase in Al₂O₃ in the slag, and Al₂O₃ has a significant effect on the crystallization rate. Moreover, with the increase in the content of Al₂O₃ in the slag, the proportion of crystals in the crystalline phase of the mold slag gradually decreases, but the type of crystals remains unchanged.
- Al₂O₃ /
- mold fluxes /
- ultra-high basicity /
- solidification characteristic /
- crystallization property

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圖 1 結晶性能測試裝置示意圖

Figure 1. Schematics of the experimental apparatus for crystallization.

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圖 2 保護渣的結晶行為.（a）渣樣熔清；（b）開始結晶（晶體比例5%）；（c）晶體生長（晶體比例50%）；（d）結晶完全（晶體比例90%）

Figure 2. Crystallization behavior: (a) melting of sample; (b) beginning of crystallization (crystal ratio is 5%); (c) crystal growth (crystal ratio is 50%); (d) complete crystallization (crystal ratio is 90%)

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圖 3 A1～A4渣的基礎性能.(a) 黏溫曲線；(b) 轉折溫度

Figure 3. Basic properties of mold fluxes A1?A4: (a) viscosity–temperature curve; (b) break temperature

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圖 4 不同Al₂O₃含量保護渣的熔化溫度

Figure 4. Melting temperature of mold fluxes with different Al₂O₃ contents

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圖 5 不同Al₂O₃含量保護渣凝固結晶計算結果. (a) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=1%; (b) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=2%; (c) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=3%; (d) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=4%; (e) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=5%; (f) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=6%; (g) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=7%; (h) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=8%

Figure 5. Calculation results of the solidification crystallization of mold fluxes with different Al₂O₃ contents: (a) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=1%; (b) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=2%; (c) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=3%; (d) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=4%; (e) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=5%; (f) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=6%; (g) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=7%; (h) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=8%

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圖 6 不同Al₂O₃含量保護渣CCT曲線與開始結晶溫度.（a）不同Al₂O₃含量保護渣CCT曲線；（b）不同Al₂O₃含量保護渣開始結晶溫度

Figure 6. CCT curves and initial crystallization temperature of mold fluxes with different Al₂O₃ contents: (a) CCT curves of mold fluxes with different Al₂O₃ contents; (b) initial crystallization temperature of mold fluxes with different Al₂O₃ contents

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圖 7 不同Al₂O₃含量保護渣的結晶時間與平均結晶速率. (a) 不同Al₂O₃含量保護渣的結晶時間；(b) 不同Al₂O₃含量保護渣的平均結晶速率

Figure 7. Crystallization time and average crystallization rate of mold fluxes with different Al₂O₃ contents: (a) crystallization time of mold fluxes with different Al₂O₃ contents; (b) average crystallization rate of different Al₂O₃ contents

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圖 8 冷凝斷面. (a) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=2%; (b) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=4%; (c) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=6%; (d) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=8%

Figure 8. Condensation section of mold fluxes: (a) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$ = 2%; (b) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$ = 4%; (c) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$ = 6%; (d) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$ = 8%

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圖 9 A1~A4保護渣的XRD圖. (a) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=2%; (b) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=4%; (c) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=6%; (d) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=8%

Figure 9. XRD of mold fluxes: (a) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=2%; (b) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=4%; (c) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=6%; (d) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=8%

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圖 10 保護渣電鏡掃描圖：(a) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=2%; (b) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=4%; (c) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=6%; (d) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=8%

Figure 10. SEM images of mold fluxes: (a) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=2%; (b) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=4%; (c) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=6%; (d) ${w_{{{\rm{A}}}{{\rm{l}}_2}{{{\rm{O}}}_3}}}$=8%

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表 1 保護渣的化學組分及其含量（質量分數）

Table 1. Chemical composition and content of mold fluxes

Sample number	Chemical composition/%
Sample number	CaO	SiO₂	CaF₂	Na₂O	MgO	Al₂O₃	Li₂O	Fe₂O₃
A1	34.81	28.74	21.55	6	3	2	2.4	1.5
A2	33.54	28.01	21.55	6	3	4	2.4	1.5
A3	32.27	27.28	21.55	6	3	6	2.4	1.5
A4	31.00	26.55	21.55	6	3	8	2.4	1.5

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表 2 保護渣能譜分析結果（質量分數）

Table 2. Results of the energy spectrum analysis of mold fluxes %

Sample number	Spectrogram	Chemical element
Sample number	Spectrogram	Ca	Si	O	F	Na	Mg	Al	Sum
A1	1	35.56	14.91	31.99	17.54	—	—	—	100.00
	2	40.77	16.33	30.42	12.48	—	—	—	100.00
	3	36.27	15.6	35.49	12.65	—	—	—	100.00
A2	1	37.6	16.1	33.0	13.3	—	—	—	100.00
	2	38.9	15.1	30.4	15.6	—	—	—	100.00
	3	39.2	15.8	31.2	13.7	—	—	—	99.90
A3	1	38.5	14.94	31.39	15.17	—	—	—	100.00
	2	41.26	15.05	29.05	14.65	—	—	—	100.00
	3	40.88	14.7	30.44	13.97	—	—	—	99.99
A4	1	38.4	14.91	32.39	13.07	—	0.53	0.7	100.00
	2	26.46	13.16	36.24	10.63	7.5	1.44	4.56	99.99
	3	30.34	13.68	33.06	13.35	3.62	1.85	4.11	100.00

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