基于Fe-H2O、Cr-H2O、Zr-H2O体系的高温电位-pH理论计算

杨旸; 杨雨; 陈云明; 曹骐; 熊伟; 鲁芸芸; 伍晓勇

doi:10.13832/j.jnpe.2022.01.0110

基于Fe-H₂O、Cr-H₂O、Zr-H₂O体系的高温电位-pH理论计算

doi: 10.13832/j.jnpe.2022.01.0110

中国核动力研究设计院，成都，610213

详细信息

作者简介:
杨　旸（1991—），女，实习研究员，现从事回路水化学腐蚀与防护工作，E-mail: m13984407381@163.com

中图分类号: TL34
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- 文章访问数: 675
- HTML全文浏览量: 236
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- 被引次数: 0
出版历程
- 收稿日期: 2021-03-02
- 录用日期: 2021-12-07
- 修回日期: 2021-12-22
- 刊出日期: 2022-02-01

Theoretical Calculation of High Temperature Potential-pH Based on Fe-H₂O, Cr-H₂O and Zr-H₂O Systems

Nuclear Power Institute of China, Chengdu, 610213, China

摘要

摘要: 本文从热力学角度出发，利用能斯特方程进行计算，研究了423、573 K温度条件下Fe-H₂O体系、Cr-H₂O体系及Zr-H₂O体系的电位-pH图（E-pH图），从理论上说明了铁、铬、锆3种反应堆结构材料的主要组成元素在高温高压水中，受电位、pH影响的腐蚀行为倾向，为后续在堆内水化学环境中进行材料电化学腐蚀试验研究以预防材料的腐蚀、延长材料的使用寿命提供了数据参考。
- 热力学计算 /
- 铁-水体系 /
- 铬-水体系 /
- 锆-水体系 /
- 高温 /
- 电位-pH图
Abstract: From the perspective of thermodynamics, this paper uses the Nernst equation to calculate the potential-pH diagrams (E-pH diagrams) of the Fe-H₂O system, Cr-H₂O system and Zr-H₂O system at temperatures of 423 K and 573 K. This paper theoretically explain the corrosion behavior tendency of the main constituent elements of reactor structural materials of iron, chromium and zirconium in high temperature and high pressure water, which are affected by potential and pH. This provides data reference for the materials electrochemical corrosion tests in the water chemical environment in reactor, preventing the corrosion of the material, and extending the service life of the material.
- Thermodynamic calculation /
- Iron-water system /
- Chromium-water system /
- Zirconium-water system /
- High temperature /
- Potential-pH diagram

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图 1 Fe-H₂O体系的E-pH图

Figure 1. E-pH Diagrams of Fe-H₂O System

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图 2 Zr-H₂O体系的E-pH图

Figure 2. E-pH Diagrams of Zr-H₂O System

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图 3 Cr-H₂O体系的E-pH图

Figure 3. E-pH Diagrams of Cr-H₂O System

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表 1 298 K常见物质的热力学数据^[9]

Table 1. Thermodynamic Data of Common Substances at 298 K　　　

物质	${ {\Delta } }G_{298}^{ {\text{θ} } }$/(KJ·mol⁻¹)	$S_{ {\text{298} } }^{ {\text{θ} }}$/(J·K⁻¹·mol⁻¹)	C_P/(J·K⁻¹·mol⁻¹）
H₂	0	130.68	28.836
O₂	0	205.152	29.378
H₂O	−237.14	69.95	75.351
H⁺	0	0	0
e⁻	0	65.285	0

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表 2 Fe-H₂O体系的主要E-pH反应式

Table 2. Main E-pH Equations of Fe-H₂O System

序号	反应式
(a)	O₂+4H⁺+4e⁻=2H₂O
(b)	2H⁺+2e⁻=H₂
1	Fe²⁺+H₂O=FeOH⁺+H⁺
2	Fe²⁺+2H₂O=Fe(OH)₂⁺+2H⁺+e⁻
3	3Fe₂O₃+2H⁺+2e⁻=2Fe₃O₄+H₂O
4	2Fe(OH)₂⁺=Fe₂O₃+H₂O+2H⁺
5	Fe²⁺+2e⁻=Fe
6	HFeO₂⁻+3H⁺+2e⁻=Fe+2H₂O

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表 3 不同温度下Fe-H₂O体系主要反应式的E-pH计算式

Table 3. E-pH Calculation Formula of Main Equations of Fe-H₂O System at Different Temperatures

序号	计算式
序号	423 K	573 K
(a)	E=1.209−0.084pH+0.0211lga_O2	E=1.116−0.114pH+0.0281lga_O2
(b)	E=0.082−0.084pH−0.042lga_H2	E=0.103−0.114pH−0.057lga_H2
1	pH=4.11+lg(FeOH⁺/Fe²⁺)	pH=2.55+lg(FeOH⁺/Fe²⁺)
2	E=1.274−0.1679pH+0.839lg[Fe(OH)₂⁺/Fe²⁺]	E=1.32−0.2274pH+0.1137lg[Fe(OH)₂⁺/Fe²⁺]
3	E=0.28−0.084pH	E=0.29−0.114pH
4	2pH=−16.74−lg{[Fe(OH)₂⁺]²}	2pH=−15.67−lg{[Fe(OH)₂⁺]²}
5	E=−0.307+lg(Fe²⁺)	E=−0.272+lg(Fe²⁺)
6	E=0.497−0.13pH+0.042lg(HFeO₂⁻)	E=0.398−0.17pH+0.057lg(HFeO₂⁻)
表中离子符号表示该离子的浓度

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表 4 Zr-H₂O体系的E-pH反应式

Table 4. E-pH Equations of Zr -H₂O System

序号	反应式
(a)	2H⁺+2e=H₂
(b)	2H₂O=O₂+4H⁺+4e⁻
1	Zr⁴⁺+H₂O=ZrO²⁺+2H⁺
2	ZrO²⁺+2H₂O=HZrO₃⁻+3H⁺
3	Zr+2H₂O=ZrO₂+4H⁺+4e⁻
4	Zr⁴⁺+2H₂O=ZrO₂+4H⁺
5	ZrO²⁺+H₂O=ZrO₂+2H⁺
6	ZrO₂+H₂O=HZrO₃⁻+H⁺
7	Zr=Zr⁴⁺+4e⁻
8	Zr+H₂O=ZrO²⁺+2H⁺+4e⁻
9	Zr+3H₂O=HZrO₃⁻+5H⁺+4e⁻

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表 5 Zr-H₂O体系的E-pH计算式

Table 5. E-pH Calculation Formula of Zr-H₂O System

序号	反应式
序号	423 K	573 K
1	2pH=3.955+lg(Zr⁴⁺/ZrO²⁺)	2pH=1.027+lg(Zr⁴⁺/ZrO²⁺)
2	3pH=−19.857+lg(ZrO²⁺/HZrO₃⁻)	3pH=−5.659+lg(ZrO²⁺/HZrO₃⁻)
3	E=1.336−0.084pH-0.021lg(Zr/ZrO₂)	E=1.445−0.114pH−0.028lg(Zr/ZrO₂)
4	4pH=−3.361+lg(Zr⁴⁺/ZrO₂)	4pH=8.08+lg(Zr⁴⁺/ZrO₂)
5	2pH=−7.316+lg(ZrO²⁺/ZrO₂)	2pH=6.96+lg(ZrO²⁺/ZrO₂)
6	pH=−12.542+lg(ZrO₂/HZrO₃⁻)	pH=−12.62+lg(ZrO₂/HZrO₃⁻)
7	E=1.41−0.021lg(Zr/Zr⁴⁺)	E =1.22−0.028lg(Zr/Zr⁴⁺)
8	E=1.489−0.042pH−0.021lg(Zr/ZrO²⁺)	E=1.25−0.057pH−0.028lg(Zr/ZrO²⁺)
9	E=1.073−0.105pH−0.021lg(Zr/HZrO₃⁻)	E=1.086−0.142pH−0.028lg(Zr/HZrO₃⁻)
(a)	E=−0.084pH	E=0.114pH
(b)	E=−1.282−0.084pH	E=−1.367−0.1144pH
表中离子符号表示该离子的浓度

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表 6 Cr-H₂O体系的E-pH反应式

Table 6. E-pH Equations of Cr-H₂O System

序号	反应式
(a)	O₂+4H⁺+4e⁻→2H₂O
(b)	2H⁺+2e⁻→H₂
1	Cr²⁺+2e⁻→Cr(s)
2	Cr³⁺+e⁻→Cr²⁺
3	H₂CrO₄+6H⁺+3e⁻→Cr³⁺+4H₂O
4	HCrO₄⁻+7H⁺+3e⁻→Cr³⁺+4H₂O
5	CrO₄^2-+4H⁺+3e⁻→Cr(OH)₄⁻
6	H₂CrO₄→HCrO₄⁻+H⁺
7	HCrO₄⁻→CrO₄⁺+H⁺
8	CrO₄^2-+8H⁺+3e⁻→Cr³⁺+4H₂O

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表 7 Cr-H₂O体系的E-pH计算式

Table 7. E-pH Calculation Formula of Cr-H₂O System

序号	计算式
序号	423 K	573 K
(a)	E=1.21−0.084pH+0.02lgP_O2	E=1.37−0.11pH+0.03lgP_O2
(b)	E=−0.084pH−0.042lgP_H2	E=−0.11pH−0.06lgP_H2
1	E=−0.817+0.042lgCr²⁺	E=−0.71+0.06lgCr²⁺
2	E=−0.17−0.084lg(Cr³⁺/Cr²⁺)	E=0.14+0.11lg(Cr³⁺/Cr²⁺)
3	E=1.26−0.168pH+0.028lg(H₂CrO₄/Cr³⁺)	E=1.14−0.22pH+0.04lg(H₂CrO₄/Cr³⁺)
4	E=1.31−0.196pH+0.028lg(HCrO₄⁻/Cr³⁺)	E=1.29−0.26pH+0.33lg(HCrO₄⁻/Cr³⁺)
5	E=0.96−0.112pH+0.028lg[CrO₄²⁻/Cr(OH)₄⁻]	E=1.06−0.15pH+0.04lg[CrO₄²⁻/Cr(OH)₄⁻]
6	pH=−2.03+lg(H₂CrO₄/HCrO₄⁻)	pH=4.02+lg(H₂CrO₄/HCrO₄⁻)
7	E=1.52−0.224 pH+0.028 lg(CrO₄²⁻/Cr³⁺)	E=1.62−0.29pH+0.04lg(CrO₄²⁻/Cr³⁺)
表中离子符号表示该离子的浓度

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