Analysis Of Deposition And Corrosion Characteristics Of Ni-P-PTFE Composite Coating On Particle Fouling

The presence of particulate fouling in heat exchangers,which is commonly found in various industrial equipment,not only reduces the heat transfer performance of heat exchangers but also introduces additional cost factors,so reducing the deposition of particulate fouling in heat exchangers has become an urgent issue.The current research on particle fouling inhibition is more focused on the influence of fouling deposition by changing the experimental conditions,while the surface modification technology provides a new idea to inhibit particle fouling deposition due to its excellent performance in inhibiting precipitation and microbial fouling problems.To this end,the Ni-P-PTFE composite coating was prepared by chemical plating process using Q235 carbon steel,which is commonly used in heat exchangers,as the experimental substrate material,and the surface morphology and elemental content of the composite coating were analyzed.By changin g the PTFE concentration in the plating solution formulation,Ni-P-PTFE composite coatings with PTFE concentrations of 8 mL/L,10 mL/L,12 mL/L,and 14 mL/L were prepared,and the contact angles of the composite coatings were measured by the three-liquid method,and then the surface energy of Ni-P-PTFE composite coatings was calculated according to the Yong equation.The results showed that the surface energy of Ni-P-PTFE composite coating decreased with the increase of PTFE concentration.TiO₂ particles of 40 nm were selected as the particle fouling medium,and a TiO ₂suspension of 5 g/L was configured in the static experiment to compare the fouling inhibition and corrosion resistance of carbon steel and Ni-P-PTFE composite plating,and to study the fouling deposition and corrosion loss of Ni-P-PTFE composite plating in the TiO₂ suspension at different surface energies（PTFE concentration）.The experimental results show that the scale inhibition and corrosion resistance of Ni-P-PTFE composite coating are str onger than those of carbon steel.For the Ni-P-PTFE composite coating,the fouling deposition and corrosion loss of the composite coating tended to decrease as the surface energy of the coating decreased,and the inhibition and corrosion resistance of the Ni-P-PTFE composite coating reached th e best at the surface energy of 26.8 m J/m~2（PTFE=12 mL/L）.The experimental conditions were changed to study the scale inhibition and corrosion resistance of Ni-P-PTFE composite plating under different surface energy（PTFE concentration）under flow conditions,where the experimental medium was 1 g/L TiO ₂ suspension,and the final experimental results were consistent with the static experimental results.In order to further study the corrosion characteristics of carbon s teel an d composite plating in TiO ₂ suspension,the polarization curves and AC impedance spectra of carbon steel and Ni-P-PTFE composite plating were measured using an electrochemical workstation.By analyzing the self-corrosion potential and self-corrosion current of carbon steel and Ni-P-PTFE composite plating in the polarization curves,the results showed that the Ni-P-PTFE composite plating has stronger corrosion resistance than carbon steel.For the Ni-P-PTFE composite coating,the corrosion resistance of the composite coating was enhanced with the increase of PTFE concentration.The corrosion process of Ni-P-PTFE composite coating surface in TiO₂ suspension was investigated by analyzing the AC impedance spectra of Ni-P-PTFE composite coating in TiO₂ suspension at different moments and fitting the best equivalent circuit model using Zview.