在不同pH值的混凝土碳化环境中,Nb微合金钢筋的被动化性能不同
Zeyun Zeng1,2, Shangjun Gu3, Jie Wang3
1College of Materials and Metallurgy, Guizhou University, Guiyang, 550025, China.
Scientific reports
|October 2, 2024
概括
在模拟混凝土孔溶液 (SCPS) 中,在pH值下降时,将 (Nb) 添加到钢筋中,可以提高被动薄膜的稳定性. 这通过促进保护性铁和氧化物层来提高耐腐蚀性.
科学领域:
- 材料科学 材料科学 材料科学
- 腐蚀工程 腐蚀工程
- 电化学 电化学 电化学
背景情况:
- 钢铁铁杆腐蚀是钢筋混凝土结构的一个主要问题.
- 了解被动薄膜形成对于提高钢筋耐用性至关重要.
- 微合金是一种提高钢材性能的潜在策略.
研究的目的:
- 研究Nb微合金钢筋上的被动薄膜的结构组成和形成机制.
- 评估模拟混凝土孔溶液 (SCPS) 中不同pH值对被动薄膜特性的影响.
- 为了比较Nb微合金钢筋与传统钢筋的性能.
主要方法:
- X射线光电子光谱学 (XPS) 喷射深度分析.
- 扫描电子显微镜 (SEM) 扫描电子显微镜.
- 电化学测试包括循环电压测量 (CV),电化学阻抗光谱 (EIS),莫特-肖特基 (M-S),时测量 (i-t) 和潜在动力极化 (DPP).
主要成果:
- 在34Nb铁杆上,被动薄膜的稳定性和紧性随着pH值的下降而增加.
- 被动膜的外层由Fe氧化物/氧化物组成,而内层包含Fe和Nb氧化物.
- 添加Nb促进了Fe和Nb氧化物的形成,增强了电化学参数 (Rct,Ecorr,Ep),并产生了PN型半导体被动膜.
结论:
- 降低pH值增强了Nb微合金钢筋上的被动薄膜的保护性.
- 微合金改进了被动膜的组成和结构,从而产生了优越的耐腐蚀性.
- 在Nb钢筋上被动薄膜的PN型半导体行为有助于降低载体密度和增加被动化率.
更多相关视频
相关概念视频
Carbonation Shrinkage
113
Atmospheric CO2 penetrates the concrete's pores and, in the presence of moisture, forms carbonic acid, which then reacts with calcium hydroxide in the hydrated cement, forming calcium carbonate. This process reduces the concrete's volume and is termed carbonation shrinkage.
The concrete's permeability is slightly reduced as calcium carbonate produced during the reaction fills its pores. Furthermore, its strength is slightly enhanced as the water released during the reaction...
The concrete's permeability is slightly reduced as calcium carbonate produced during the reaction fills its pores. Furthermore, its strength is slightly enhanced as the water released during the reaction...
113
Corrosion of Reinforcement
165
The corrosion of steel reinforcement within concrete is a process influenced by the material's inherent properties and external factors. The high pH level of around 13, provided by calcium hydroxide present in concrete, initially protects the steel reinforcement by promoting the formation of a passive iron oxide layer on its surface.
However, over time and under certain conditions like carbonation, chloride ingress, and cracking this protective state can be compromised. Steel has areas with...
However, over time and under certain conditions like carbonation, chloride ingress, and cracking this protective state can be compromised. Steel has areas with...
165
Acid Attack on Concrete
194
When acids come into contact with concrete, they initiate a chemical reaction that dissolves the hydrated cement paste. This process leads to softening and structural weakening of the concrete. This issue is commonly observed in environments such as chimneys, sewers, and industrial settings. The severity of the damage increases as the pH of the water interacting with the concrete drops below 6.5. In particular, a pH under 4.5 can cause significant concrete damage.
The rate at which hydrogen...
The rate at which hydrogen...
194
Testing Water Quality
103
When the quality of water for concrete preparation is uncertain, its impact on the setting time of cement and compressive strength of mortar is assessed by comparison with de-ionized or distilled water benchmarks. American Society for Testing and Materials (ASTM) C1602 requires the setting times to be within 90 minutes of the control, British Standard (BS) 3146:1980 allows a 30-minute variance in the initial setting, while British Standards European Norm (BS EN) 1008 specifies initial setting...
103
Quality of Water
88
In concrete preparation, the quality of water is paramount as it affects the strength and durability of the concrete. Potable water is usually preferred; however, it must not have excessive sodium or potassium to prevent compromising the concrete's integrity. Water quality is typically evaluated based on impurities such as dissolved solids, chlorides, and sulfates, and its pH value is ideally between 6 and 8. Even slightly acidic natural water may be acceptable unless it contains harmful...
88
Effect of Sea Water on Concrete
197
Concrete exposed to seawater can undergo degradation like the dissolution of ettringite and gypsum, increasing the material's porosity and decreasing its strength. In contrast, the crystallization of salts within the concrete's pores can cause expansion, particularly above the waterline where evaporation occurs. Nonetheless, this expansion only happens when seawater, enabled by the concrete's permeability, manages to infiltrate the structure.
Concrete in areas between tide marks,...
Concrete in areas between tide marks,...
197


