Preparation And Properties Of Polyaniline/Graphite Nanosheets Composite Conductive And Anticorrosive Coatings

Electric grounding grid is an important device to ensure the safe operation of the power system. The grounding grid which is deeply buried underground for a long time is prone to be destroyed by electrochemical corrosion. So far the most common method of using galvanized steel grounding can not fundamentally solve the corrosion problem of grounding grid. As a kind of functional coating, conductive and anticorrosive coating with conductivity and corrosion resistance provides a new way to solve the corrosion problem of grounding grid.The conductivity and corrosion resistance of traditional conductive and anticorrosive coating are poor, easy pitting. Novel conductive and anticorrosive coating which was based on polyaniline(PANI) and graphite nanosheets(Nano-G) as filler, epoxy resin(EP) as a film-forming resin was investigated to improve the conductivity,corrosion resistance and pitting corrosion resistance of coating. The morphology, structure and thermal stability of PANI and Nano-G were analyzed by SEM, FT-IR and TG. The effect of coupling agent on the dispersion properties of PANI was analyzed by static sedimentation test and SEM. Conductive properties of PANI and coating were characterized by electrical conductivity test. The corrosion resistance and pitting corrosion resistance of the coating were characterized by immersion test, salt spray test and Tafel polarization curves.1. The optimum synthesis of hydrochloric acid doped polyaniline(PANI-HCl) was determined as follows: reaction temperature is 0℃, the concentration of hydrochloric acid is 1.0 mol/L, molar ratio of ammonium persulfate(APS) and aniline is 1:1, reaction time is 6 h. The preparation process of the eigenstate polyaniline(PANI-EB) was prepared by doping the hydrochloric acid doped polyaniline with 0.1 mol/L ammonia water for 4 hours. The optimum synthesis of camphor sulfonic acid doped polyaniline(PANI-CSA): reaction temperature is 0℃, molar ratio of camphor sulfonic acid and polyaniline is 1:1, reaction time is 8 h.2. The polyaniline was uniformly dispersed in the epoxy resin by electing silane coupling agent KH570 and adding with pretreatment methods. PANI-EB has the best corrosion resistance and scratch resistance. The corrosion resistance and scratch resistance performance of the coating was the best when the content of PANI- EB was 0.2%.3. The conductive property of the coating was improved by the addition of Nano-G. The conductive property of the coating increased first and then decreased with the increase of the content of Nano-G. The conductivity of the coating was the best, volume resistivity of the coating was 1.72 Ω·cm when the content of Nano-G was 7.5%. The coating had a good corrosion resistance and scratch resistance. The adhesion of the coating is level 1.The PANI/Nano-G/EP conductive and anticorrosive coatings prepared this article not only had good conductivity and anticorrosive performance, but had unique scratch resistance performance. The coating can solve the problem of easy pitting, effectively prolong the service life of grounding network and satisfy the application requirements for electric grounding grid.