| Bonded ceramic coatings,as an effective method to improve the wear and corrosion resistance of metal components,are widely used in the core components of equipment.However,the problem of high wear and easy detachment of bonded ceramic coatings in aquatic environments limits their application in marine equipment.Therefore,this paper planned to carry out researches on the design strategy of phosphate bonded ceramic coatings under water lubrication conditions,that is,based on the wear resistance of bonded ceramic coatings and the water lubrication of polyacrylamide sodium alginate（PAAM-SA）hydrogel,in-depth researched on the impact of PAAM-SA hydrogel content on tribological properties,and its research results will provide a good reference for the application of bonded ceramic coatings in the water environment.Firstly,phosphate bonded ceramic coatings and PAAM-SA/phosphate bonded ceramic coatings were prepared.Phosphate bonded ceramic coatings with different PS contents were prepared on 304L stainless steel using alumina（Al2O3）as ceramic aggregate,polystyrene（PS）as pore forming agent,aluminum dihydrogen phosphate（AP）as binder,and zinc oxide（Zn O）as curing agent through spray thermal curing;On this basis,PAAM-SA hydrogel was pressed into the micropores left by PS decomposition in vacuum,and the PAAM-SA/phosphate bonded ceramic coating was successfully prepared by ultraviolet（UV）triggering polymerization.Secondly,the solidification mechanism of phosphate bonded ceramic coatings was revealed through phase composition and thermal performance analysis.Al2O3 and Zn O reacted with AP to generate bonding phases to promote the coating curing reaction.When the temperature reached 300℃,PS decomposed and left micropores in the coating;The chemical reaction of acrylamide（AAM）monomer,sodium alginate and crosslinking agent N,N-methylenebisacrylamide was confirmed by the characterization of the product of PAAM-SA hydrogel polymerization by infrared spectrum;By comparing the performance of phosphate bonded ceramic coatings and PAAM-SA/phosphate bonded ceramic coatings,it was found that the internal structure of PAAM-SA/phosphate bonded ceramic coatings is denser,the surface is smoother,the bonding strength and impact resistance are stronger,and they exhibit high hydrophilicity and high swelling ability in contrast to phosphate bonded ceramic coatingsFinally,the friction and wear behavior of phosphate bonded ceramic coatings and PAAM-SA/phosphate bonded ceramic coatings in dry and wet environments were investigated,and the wear mechanism of the coating and the water lubrication mechanism of PAAM-SA hydrogel were clarified.Under dry friction,PAAM-SA hydrogel was ground into powder,which effectively promoted the peeling of surface cracks on the wear scar,making the surface of PAAM-SA/phosphate bonded ceramic coating smoother than that of phosphate bonded ceramic coating.Therefore,the friction coefficient and wear rate of PAAM-SA/phosphate bonded ceramic coating were lower than that of phosphate bonded ceramic coating;In the water environment,PAAM-SA hydrogel was stripped and ground during the friction process.The hydrogel fragments absorbed water molecules and exchanged with the surrounding free water molecules,making the coating surface form an effective lubrication layer,thus reducing the shear force between friction surfaces.Therefore,the friction coefficient and wear rate of PAAM-SA/phosphate bonded ceramic coating were also lower than those of phosphate bonded ceramic coating.The friction coefficient and wear rate of PAAM-SA/phosphate bonded ceramic coating decreased first and then increased with the increase of hydrogel content,that is,when the content of PS was 4 wt%,the friction coefficient and wear rate of PAAM-SA/phosphate bonded ceramic coating were the lowest,and the friction coefficient and wear rate were 35%and 85%lower than those of phosphate bonded ceramic coating respectively.The above results can effectively expand the engineering application field of hydrogel lubricating materials. |
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