Fe/SiO2 Composite Coated Optical Fiber for Corrosion Monitoring

Abstract

It is important to monitor and locate internal corrosion over the long-distance natural gas pipelines in real time before catastrophic failures to ensure safe, secure, and reliable transportation of natural gas and reduce the environmental impact from methane emission. Optical fiber based sensors provide many advantageous features, especially the distributed sensing over a long distance and the inertness in the presence of flammable gas, among others. To take advantage of these features, corrosion proxy sensing materials are a key enabling component for an optical fiber corrosion sensor. We have previously demonstrated a distributed optical fiber corrosion sensor, and reported early results on Fe/SiO2 composite coating. To further improve the sensing performance, detailed studies were performed to investigate the Fe/SiO2 composite coating. The Fe/SiO2 composite layers are coated onto the optical fiber using sol-gel and electroless plating methods, respectively, with controlled morphologies. The coating is characterized with SEM and XPS. Tested in corrosive solutions at room temperature, optical responses are measured for corrosion monitoring. The light transmission increases as Fe dissolves away due to the decrease in light absorption of the metallic layer. Different morphologies are compared to optimize sensing performance of the Fe/SiO2 composite coated optical fiber corrosion sensor.