Corrosion Resistance Mechanism of Mica–Graphene/Epoxy Composite Coating in CO<sub>2</sub>-Cl<sup>−</sup> System
Shi-Dong Zhu,
Yan-Peng Li,
Hong-Wei Wang,
Jin-Ling Li,
An-Qing Fu,
Gang Chen,
Dong Ma,
Xuan-Peng Li,
Frank Cheng
Affiliations
Shi-Dong Zhu
School of Materials Science and Engineering, Xi’an Shiyou University, Xi’an 710065, China
Yan-Peng Li
School of Materials Science and Engineering, Xi’an Shiyou University, Xi’an 710065, China
Hong-Wei Wang
The 8th Oil Production Plant, PetroChina Changqing Oilfield Company, Xi’an 710014, China
Jin-Ling Li
Shaanxi Oil and Gas Pollution Control Technology and Reservoir Protection Key Laboratory, College of Chemistry and Chemical Engineering, Xi’an Shiyou University, Xi’an 710065, China
An-Qing Fu
State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, CNPC Tubular Goods Research Institute, Xi’an 710077, China
Gang Chen
Shaanxi Oil and Gas Pollution Control Technology and Reservoir Protection Key Laboratory, College of Chemistry and Chemical Engineering, Xi’an Shiyou University, Xi’an 710065, China
Dong Ma
School of Materials Science and Engineering, Xi’an Shiyou University, Xi’an 710065, China
Xuan-Peng Li
State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, CNPC Tubular Goods Research Institute, Xi’an 710077, China
Frank Cheng
Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada
The working environment for tubing in oil and gas fields is becoming more and more serious due to the exploration of unconventional oil and gas resources, leading to the increasing need for a protective internal coating to be used in tubing. Therefore, a new mica–graphene/epoxy composite coating with different graphene contents (0.0, 0.2, 0.5, 0.7, and 1.0 wt.%) was prepared to improve the tubing resistance to a corrosive medium, an autoclave was used to simulate the working environment, and an electrochemical workstation assisted by three-electrodes was used to study the electrochemical characteristics of the coating. The results showed that the addition of a certain amount of graphene into the mica/epoxy coating significantly improved the corrosion resistance of the composite coating, and when the graphene content increased, the corrosion resistance of the mica/epoxy coating first increased and then decreased when the corrosion current density of a 35 wt.% 800# mica/epoxy coating with a 0.7 wt.% graphene content was the lowest (7.11 × 10−13 A·cm−2), the corrosion potential was the highest (292 mV), the polarization resistance was the largest (3.463 × 109 Ω·cm2), and the corrosion resistance was improved by 89.3% compared to the coating without graphene. Furthermore, the adhesion of the coating with 0.7 wt.% graphene was also the largest (8.81 MPa, increased by 3.4%) and had the smallest diffusion coefficient (1.566 × 107 cm2·s−1, decreased by 76.1%), and the thermal stability improved by 18.6%. Finally, the corrosion resistance mechanism of the composite coating with different graphene contents at different soaking times was revealed based on the electrochemistry and morphology characteristics other than water absorption and contact angle.
