Plasma electrolytic oxidation(PEO) processes were carried out to produce ceramic layers on 6061 aluminum substrates in four kinds of electrolytes such as silicate and aluminate solution with and without sodium fluoros...Plasma electrolytic oxidation(PEO) processes were carried out to produce ceramic layers on 6061 aluminum substrates in four kinds of electrolytes such as silicate and aluminate solution with and without sodium fluorosilicate.The PEO processes were carried out under a hybrid voltage(260 V DC combined with 200 V,60 Hz AC amplitude) at room temperature for 5 min.The composition,microstructure and element distribution analyses of the PEO-treated layers were carried out by XRD and SEM & EDS.The effect of the electrolyte contents on the growth mechanism,element distribution and properties of oxide layers were studied.It is obvious that the layers generated in aluminate solutions show smoother surfaces than those in silicate solutions.Moreover,an addition of fluorine ion can effectively control the layer porosity;therefore,it can enhance the properties of the layers.展开更多
The silver-palladium(Ag-Pd) alloy coating as a solid lubricant was investigated for its application to the high temperature stud bolts used in nuclear power plants.A hex bolt sample was prepared in the following steps...The silver-palladium(Ag-Pd) alloy coating as a solid lubricant was investigated for its application to the high temperature stud bolts used in nuclear power plants.A hex bolt sample was prepared in the following steps:1) bolt surface treatment using alumina grit blasting for cleaning and increasing the surface area;2) nickel(Ni) film coating as a glue layer on the surface of the bolt;and 3) Ag-Pd alloy coating on the Ni film.The films were deposited by using a direct current(DC) magnetron sputtering system.The thickness and composition of the Ag-Pd alloy film have effect on the friction coefficient,which was determined using axial force measurement.A 500 nm-thick Ag-Pd(80-20,molar ratio) alloy film has the lowest friction coefficient of 0.109.A cyclic test was conducted to evaluate the durability of bolts coated with either the Ag-Pd(80-20) alloy film or N-5000 oil.In a cycle,the bolts were inserted into a block using a torque wrench,which was followed by heating and disassembling.After only one cycle,it was not possible to remove the bolts coated with the N-5000 oil from the block.However,the bolts coated with the Ag-Pd(80-20) alloy could be easily removed up until 15 cycles.展开更多
基金Korea Research Foundation Grant (KRF-2006-005-J02703)
文摘Plasma electrolytic oxidation(PEO) processes were carried out to produce ceramic layers on 6061 aluminum substrates in four kinds of electrolytes such as silicate and aluminate solution with and without sodium fluorosilicate.The PEO processes were carried out under a hybrid voltage(260 V DC combined with 200 V,60 Hz AC amplitude) at room temperature for 5 min.The composition,microstructure and element distribution analyses of the PEO-treated layers were carried out by XRD and SEM & EDS.The effect of the electrolyte contents on the growth mechanism,element distribution and properties of oxide layers were studied.It is obvious that the layers generated in aluminate solutions show smoother surfaces than those in silicate solutions.Moreover,an addition of fluorine ion can effectively control the layer porosity;therefore,it can enhance the properties of the layers.
基金Project supported by Power Research and Development Program funded by Ministry of Knowledge Economy and Korea Institute of Materials Science,a subsidiary branch of Korea Institute of Machinery and Materials
文摘The silver-palladium(Ag-Pd) alloy coating as a solid lubricant was investigated for its application to the high temperature stud bolts used in nuclear power plants.A hex bolt sample was prepared in the following steps:1) bolt surface treatment using alumina grit blasting for cleaning and increasing the surface area;2) nickel(Ni) film coating as a glue layer on the surface of the bolt;and 3) Ag-Pd alloy coating on the Ni film.The films were deposited by using a direct current(DC) magnetron sputtering system.The thickness and composition of the Ag-Pd alloy film have effect on the friction coefficient,which was determined using axial force measurement.A 500 nm-thick Ag-Pd(80-20,molar ratio) alloy film has the lowest friction coefficient of 0.109.A cyclic test was conducted to evaluate the durability of bolts coated with either the Ag-Pd(80-20) alloy film or N-5000 oil.In a cycle,the bolts were inserted into a block using a torque wrench,which was followed by heating and disassembling.After only one cycle,it was not possible to remove the bolts coated with the N-5000 oil from the block.However,the bolts coated with the Ag-Pd(80-20) alloy could be easily removed up until 15 cycles.
