Study On The Preparation And Properties Of Self-Assembled Monolayers

Carbon steel is active and easy to be oxidized, so it is hard to it isdifficult to form self-assembled monolayers on the surface. in order solvethis problem, A purpose is put forward that a layer of thin and compactphosphate coating is first formed on the surface of steel, and thenalternatively sodium silicate layer and siloxane layer are adsorbed by thelayer by layer technology. in the same time idiographic progress ofself-assembling and anticorrosive performance of self-assembledmonolayers are discussed. The result of experimentation indicates thatAdding some accelerant and surface active agent to zinc oxide,phosphoric acid and nitric acid, an optimal batch formula is accomplished.the optimal technics is dipping carbon steel with clean surface into asolution of H3PO4 50ml/L, H3NO3 10ml/L, ZnO 23g/L, NaNO2 1．5g/L,C6H8O7 1．5g/L for 10 to 15 minutes at a temperature of 40 to 60 degree.this progress has the merit of broad range of temperature, stable, shorttime, few settlements, easy to adjust, good performance of anticorrosionand good cohesion to self-assembled monolayers. the progress ofalternatively sodium silicate layer and siloxane layer adsorbed on thesurface of phosphate coating the sort of silicones, time of hydrolyzing,concentration of water glass and heating influence the performance ofanticorrosion are key factors, the optimizing progress of self-assemblingis as follows: dip the pretreated carbon steel into KH-560 hydrolyticsolution for 30 minutes, and lift it slowly and then dip into 0．1mol/Lwater glass for 15 minutes, the self-assembled monolayers can beprepared after 5-10 times recycled treatment. The bluestone bitexperiment of the self-assembled monolayers prepared under such condition can reach 723s, which indicated that the monolayer canseparate the metal substrate and the surrounding environment effectively,and therefore protect the metal substrate. Electrochemical experimentresults indicate that the root cause of excellent anticorrosive performanceof the self-assembled monolayers is to make the metal under passivationstatus.