Research On Biomimetic Preparation Based On Crab Surface Microstructure And Analysis Of Antifouling Performance

When ships navigate in the ocean,the lower part of the ship's waterline immersed in sea water will be attached with the fouling organisms.The fouling organism has brought great harm to the ship operation,including the increase of the fuel consumption as well as aggravation of hull corrosion,which reduces the ship's productivity and safety.The traditional method is antifouling hull coating,but most of these coatings are toxic and do harm to the marine environment.With gradually increased awareness of environmental protection,the toxic coatings will be eliminated soon or later and development of new environmentally and friendly antifouling technology for ship body surface will become main trend in the future.In nature,many marine organisms have their own characteristics of preventing fouling.The most studied objectives like sharks,dolphins and marine shells can maintain their surface cleanliness through the micro structure of their own epidermis,which provides an important reference for the construction of micro structure antifouling coatings.Inspired by this idea,this paper selected the crab as the main research object.Different from the sharks and dolphins swimming in the sea and have high mucus secretion,crabs live in the general static cracks in the rock.Even if their motion is relatively slow and they do not secrete mucus on surface,selecting crabs as the bionic object conforms to the fact that marine fouling generally occurs at anchor.Through the observation and analysis of the crab shell surface by using the digital microscope and scanning electron microscope,there was a composite scale microstructure on the surface of crabs.It has macrostructure exceeding 100 ?m and less than 10?m structure.According to the statistical morphology extraction and data analysis,the micro structure of the surface microstructure characteristics of crab shell was designed based on 6 different scales,the former 3 kinds of structure are 20 ?m high,diameter were 100 ?m,150 ?m and 200 ?m.The space between the cylinder was 100 ?m,150 ?m and 150 ?m respectively.The other 3 kinds of structures are 3 ?m high and 3 ?m diameter cylinder,and the distance between cylinder and cylinder is 4 ?m,7 ?m and 10 ?m respectively.These 6 kinds of microstructures were fabricated on the surface of the silicon wafer by reactive ion etching(RIE).The results of laser confocal microscope test showed that the microstructure of the silicon wafer surface is in accordance with the design requirements.The contact angles of 6 kinds of structures were measured.The analysis results showed that all the surface contact angles were increased.The contact angle of the micro structure surface with 4 ?m spacing was 125°,which is most obvious among experiment groups.By using PMMA and SMAR,the microstructures of 6 different silicon wafers were reformed by using the complex method.About the complex effect and the complexity of the operation,it easier to apply SMAR process than PMMA and thus SMAR is more suitable for the complex selection material.The anti-fouling performance test was carried out by laboratory static attachment experiment on the surface with different scale microstructures which were prepared by the complex method.The results showed that the surface of both SMAR and PMMA samples spacing 100 ?m and 150 ?m have boosted the attachment of diatoms to some extent.Therefore,the macrostructure of crab shell surface exceeding 100?m had no antifouling effect.The compound surfaces with 4 ?m and 7 ?m space distance have the best antifouling effect.The SMAR replica with 4 ?m and 7 ?m space distance can cause the attachment rate of algal reach to 53% and 63% respectively while can reduce the attachment rate of P.triangulationm to 45% and 60% respectively.At the same time,PMMA surfaces with distance 4 ?m and 7 ?m can reduce the attachment rate of to 46% and 23%,respectively and the attachment rate of the tricornutum algal decreased to 52% and 40% respectively.Other two surfaces of different material with same space distance(100 ?m)increased the attachment rate of algae,except the attachment rate of scaphoid algae decreased by 9% which affected by PMMA process.According to the analysis about the relationship between the inhibition rate and different scale surface structure,the crab's surface composite structure with its size is less than 10?m can bring anti-fouling effect and it could become more remarkable when its space distance is between 4-7 ?m.