Preparation And Performance Of Diversified And Enhanced Anti-scouring Coating

The submarine door is installed at the outer shell of the sea chest at the bottom of the ship.It is the centralized inlet for the engine water such as engine cooling water,ballast water and fire water.It is very important for the normal operation of the engine and the navigation of the ship.At present,the application of anti-corrosion coating and coating of damper plate or Dacromet coating method is adopted.Because seawater scouring is mixed with sediment impact,the coating is easy to wear and peel off,and the coating anti-corrosion performance and service life are reduced.High durability and anti-scour coating are important ways to solve the anti-scour of the submarine door and prolong the life cycle of the ship.In this paper,carbon fiber-polysiloxane-polyurea coatings were prepared.The effects of polysiloxane and carbon fiber on the mechanical properties,corrosion resistance and erosion resistance of polyurea coatings were investigated.Polysiloxane-polyurea and carbon fiber were discussed./ Formation mechanism of polyurea composite coating.The molecular weight of the aspartic acid ester and the structure of the substituent are different,and the secondary amino group has different reactivity,which affects the structure and properties of the polyaspartate polyurea.The effects of polyaspartic acid ester on the thermodynamic properties,structure and mechanical properties of polyurea resin were investigated by adjusting the molar ratio of polyaspartic acid esters with different molecular weights and different substituents.Ultra-high temperature comprehensive thermal analysis showed that the poly-aspartate polyurea has a thermal weight loss rate of 10% at 389 ° C,a thermal decomposition temperature higher than 490 ° C,and can be used in the range of 50-250 ° C for a long time.The ester polyurea has high thermal stability;differential scanning calorimetry and atomic force microscopy analysis show that the large molecular weight of the 4,4'-3-isoheptane bicyclohexylene structure in the polyaspartate polyurea system The molar ratio of polyaspartate(F524)increases,and the hard segment of the polyurea system increases,breaking the order of soft segments,increasing the restriction on the activity of polyurea soft segments,and reducing the The regularity of the distribution of the soft and hard segments promotes the mutual penetration of the polyurea soft and hard segments,thereby increasing the glass transition temperature of the polyurea material.From the mechanical point of view,the molar ratio of the large molecular weight polyaspartate increases,changing the crosslink density of the soft and hard segments of the polyurea system,thereby improving the tensile properties and Shore hardness of the polyurea material.The best mechanical properties are obtained when the molar ratio of F524 to F520 is 1:1.The silane coupling agent A171 with double bond and amino reactive group was selected to be hydrolyzed and polymerized by KH792 to prepare a composite polysiloxane resin.The stability and stability of the silane solution and the molecular structure were characterized by conductivity and infrared spectroscopy.The effect of polysiloxane content on the performance of polyurea was investigated.The results showed that A171 having a carbon-carbon double bond structure and KH792 having an amino structure were subjected to addition-hydrolysis-polymerization to synthesize a polysiloxane resin having a secondary amino group and a silanol structure.The addition of polysiloxane increases the hard segment structure of different molecular weights in the polyurea system,breaking the order of soft and hard segments,increasing the degree of cross-linking of polyurea soft and hard segments,and the polyurea molecules are more tightly bound.The thermal stability of the polyurea resin can be improved;at the same time,the content of the hard segment increases,which strengthens the restriction of the soft segment on the soft segment,promotes the mutual penetration of the polyurea soft and hard segments,and the glass transition temperature of the polyurea resin.improve.The degree of crosslinking of the soft and hard segments in the polyurea system is improved,and the mechanical properties of the polyurea composite are significantly improved.When the mass fraction of the polysiloxane is 6%,the tensile strength of the composite polyurea system reaches 7.78 MPa.The adhesion to the substrate is increased to 11.57 MPa.The formation mechanism of the polysiloxane-polyurea composite material is that the carbon-carbon double bond of A171 is firstly reacted with the primary amino group of KH792,and the two are separately hydrolyzed and hydrolyzed to form a polysilicon having a large steric hindrance secondary amino group.An oxane wherein the amino group is crosslinked with a polyisocyanate to form a polysiloxane polyurea.The introduction of polysiloxane increases the small molecular hard segment of the polyurea system with the silicon-oxygen bond as the main chain,which improves the tensile properties and bonding strength of the composite.The effects of different surface modification treatments on the surface structure of carbon fiber were characterized by infrared spectrometer(FIRT)and X-ray photoelectron spectroscopy(XPS).The influence of carbon fiber content on the mechanical properties and erosion resistance of composite polyurea materials was investigated..The results show that the surface modification and activation treatment of carbon fiber is the basis for the preparation of carbon fiber/polyurea composite coating.The carbon fiber can be modified to obtain different interfaces of structure,surface energy and reactivity.After nitric acid oxidation,only a small amount of C=O and CN polar groups are formed on the surface.After KH792 silanization treatment,more surface active groups such as-NH and-OH are introduced into the surface to prepare carbon fiber and polyurea composite coating.A cross-linking point is provided.The carbon fiber forms a chemical bond with the polyurea through the active group on the surface,branches into the coating system,and forms a resin-fiber grid-like composite structure through the bridging connection of the carbon fiber,which greatly improves the tensile strength of the polyurea coating.Elongation,hardness and resistance to sand-washing.When the surface modification of the carbon fiber is 1g,the tensile strength of the composite polyurea coating is increased from 4.57 MPa to 14.45 MPa,and the adhesion between the coating and the substrate is increased from 9.66 MPa to 122.95 MPa.The coating is in the sediment-containing seawater.When washed for 60 days,the mass loss rate was 2.46%.Can meet construction requirements.