Hydrofluoric Acid Medium Stainless Steel Corrosion Inhibitor For

This　paper　studied　the　corrosion　velocity　and　corrosion　inhibition　efficiency　of　stainless　steel　in　5%　hydrofluoric　acid　with　nearly　a　hundred　of　compounds　seperatly　　by　weight-loss　method.Then　a　few　kinds　of　compounds　with　good　corrosion　inhibition　effect　have　been　got　in　hydrofluoric　acid　solution.　　　　In　these　compounds　thiourea,sodium　thiocyanate　storage　tanks,propiolic　alcohol　and　cetyl　pyridinium　bormide　are　selected　as　research　objects.Their　corrosion　inhibition　action　of　stainless　steel　in　hydrofluoric　acid　is　studied　by　adsorption　theory　and　electrochemical　polarization-curve　method,the　mechanism　of　corrosion　inhibition　action　is　analyzed.the　result　shows　that　the　single　molecule　layer　of　these　compounds　is　adsorbed　on　the　surface　of　the　stainless　steel　and　followed　Langmuir　isothermal　equation.　the　adsorption　procedure　of　propiolic　alcohol　is　endothermic　reaction,　the　adsorption　ability　and　corrosion　inhibition　efficiency　increased　when　temperature　rised.　The　adsorption　procedure　of　other　three　compounds　are　all　exothermic　reaction , the　adsorption　ability　and　corrosion　inhibition　efficiency　decreased　when　temperature　increased.At　60℃,their　corrosion　inhibition　efficiency　are　96.98%,96.54%,95.23%　and　86.86%.They　are　all　mixed　type　inhibitors　except　that　thiourea　is　anodic　type　inhibitor.The　corrosion　current　is　decreased　by　them　in　different　degree.　　　These　compounds　used　respectively　have　low　corrosion　inhibition　efficiency　in　high　temperature　and　can't　meet　practical　require.So　a　composite　corrosion　inhibitor　named　XN-1　with　excellent　corrosion　inhibition　efficiency　is　composed　by　orthogonal　method.Corrosion　inhibition　action　of　this　composite　corrosion　inhibitor　has　been　evaluated.The　corrosion　rate　of　stainless　steel　in　hydrofluoric　acid　has　been　determined　with　different　temperature,different　concentration　of　hydrofluoric　acid　and　different　time.It　shows　that　under　high　temperature,strong　acidity　and　when　long　time　goes,this　composite　corrosion　inhibitor　possess　excellent　corrosion　inhibition.When　this　composite　corrosion　inhibitor　exist,　The　corrosion　velocity　of　stainless　steel　accorded　with　national　standard　(<6　g·m-2·h-1).　Electrochemical　polarization-curve　experiment　testify　the　composite　corrosion　inhibitor　is　an　mixed　type　inhibitor.　The　SEM　　photos　of　stainless　steel　surface　have　been　taken　under　different　corrosion　condition.It　has　no　heterogeneous　corrosion　such　as　dot　corrosion　and　aperture　corrosion　on　stainless　steel　surface.So　the　mechanical　performance　of　stainless　steel　has　no　changed　when　this　composite　corrosion　inhibitor　exsit.It　emply　this　composite　corrosion　inhibitor　is　an　excellent　high-temperature　corrosion　inhibitor　of　stainless　steel　in　hydrofluoric　acid　solution.