| Pipeline corrosion in soil is one of the main factors causing threat trouble in life and production. Serving as potential monitor, reference electrode directly affects the reliability of corrosion data and the evaluation of cathodic protection for metallic strutures. The present Cu/CuSO4 reference electrode used in soil is not adeguate for long-term stable monitoring, and its service life is only 510 years. Therefore, it is necessary to develop a high performance Cu/CuSO4 reference electrode.With nano-SiO2, and sulphate acid and a kind of colloid electrolyte is synthesized by sol-gel method. It is placed outside the reference electrode as a layer of gel electrolyte so as to decrease the leaching of Cu2+ and raise the life of the reference electrode. The gel is stable and conductive. Its conductivity is 100Sm-1. The rate of dehydration is 3.9 ×10-3ml h-1 at 25 ℃, and the diffusivity is 5.3 ×10-10 m2 s-1. Form 25 ℃ to 50℃, the gel electrolyte has a little affect change with temperature, and can serve in acidic or alkaline environment.The performance of the gel electrode in simulating soil solution is measured as follows: the potential of the electrodes ranging from 60mV to 80mV (vs. SCE) with potential fluctuating no more than ± 10mV, enough resistance to polarization, and the temperature coefficient being near 0.9mV℃-1. It is rapidly recoverable with potential in dry-wet environment. The Cu2+ effusion rate of the reference electrode without gel electrolyte is 2 times larger than that with colloid electrolyte, which means that gel electrolyte can extend the life of the reference electrode significantly.
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