The Experimental Investigation Of Slime-forming Bacteria Fouling And Corrosion Characteristics On Electroless Ni-Zn-P Surface

Heat exchanger’s microbial fouling problem is one of the most common fouling in industrial circulating cooling water.At present,the main emphasis of energy saving has shifted to the microbial fouling because of its complex machanism and unavoidable harmfulness.Technology of surface modification has provided a new way or feasibility for heat exchange equipment cooling water microbial fouling reduction and mitigation.Chemical plating has became the research hotspots of surface modification owed to its advantage of operation and low price.In this article the surface modification on carbon steel surface is realized by chemical plating,then the Ni-Zn-P electroless deposit is prepared to obtain the modified surface with low surface energy,better anti-fouling and corrosion resistance.The experiment investigation of Ni-Zn-P electroless coating microbial fouling characteristic in mucus production bacteria suspension is carried.In the present project,the low-carbon steel which is common used as the heat-exchange surface was modified by using method of electroless Ni-Zn-P,and the electroless Ni-Zn-P coating with micromesh grain was obtained.Performance analysis of Ni-Zn-P electroless coating is carried to compare the micro surface topography differences with carbon steel and Ni-P electroless deposit.The element content analysis of electroless plating is investigated with energy dispersive analysis.Contact angle measure and surface energy calculation of electroless plating is carried to compare surface energy of the three samples.The Slime-forming bacteria experiments were carried out.The fouling and corrosion characteristics of the Ni-Zn-P coating,carbon steel and Ni-P coating were obtained and compared.In the experiments,weighing method was used to record the change of the fouling and corrosion.The optical turbidity method was used to record the number of the bacteria.The morphology of the three samples was observed before and after the microbial fouling experiment by using SEM.For the concentration of microbial suspension changing,the effect of concentration changing on suspension adhesion ability is analyzed by using the adhesive work between surface and microbial suspension.At first,on the basis of mucus production bacteria,configurating the OD600 value of mucus production bacteria suspension is 0.2,0.5 and 0.8 respectively.Based on the bacteria suspension OD values measurement,bacteria suspension liquid surface tension and contact angle are measured by using JC2000C1 contact angle/interfacial tension meter every 12 h.At last,the formation process of microbial fouling is analyzed by associated change analysis ofOD and bacteria suspension adhesion work for different surfaces,Electrochemistry method was used to study the corrosion resistance of the samples in the Slime-forming bacteria.By polarization curve change situation in mucus production bacteria suspension,the microbial corrosion resistance of three samples is concluded,and based on the analysis of total impedance value changing with soaking time,the surface corrosion and microbial fouling adhesion process are analyzed consequently.The results show that the biofouling resistance and corrosion resistance of the electroless Ni-Zn-P was better than electroless Ni-P alloy coating and the low-carbon steel surface.The Ni-Zn-P plating can effectively inhibit the fouling and corrosion growth of microorganisms.