Systems and methods for treating a metal substrate

Abstract

Disclosed herein are systems and methods for treating a magnesium or a magnesium alloy substrate. The system includes a cleaning composition having a pH greater than 8.5 or a solvent, and a pretreatment composition comprising an organophosphate compound and/or an organophosphonate compound. The method includes contacting a substrate surface with the cleaning composition or the solvent, and contacting the surface with the pretreatment composition. Also disclosed are substrates treated with one of the systems or methods. Also disclosed are magnesium or magnesium alloy substrates wherein, between the air/substrate interface and 500 nm below the air/substrate interface (a) oxygen and magnesium are present in a combined amount of at least 70 atomic %; (b) carbon is present in an amount of no more than 30 atomic %; and/or (c) fluoride is present in an amount of no more than 8 atomic %, wherein atomic % is measured by XPS depth profiling.

1 . A system for treating a substrate comprising:
 a cleaning composition having a pH greater than 8.5 or a solvent; and   a pretreatment composition comprising an organophosphate compound, an organophosphonate compound, or combinations thereof;   
       wherein the substrate comprises magnesium or a magnesium alloy. 
     
     
         2 . (canceled) 
     
     
         3 . The system of  claim 1 , wherein the pretreatment composition has a solids content of 1.25% to 25% by weight based on total weight of the pretreatment composition. 
     
     
         4 . The system of  claim 1 , wherein the organophosphate compound comprises a phosphatized epoxy. 
     
     
         5 . (canceled) 
     
     
         6 . The system of  claim 1 , wherein the organophosphonate compound comprises a phosphoric acid or a phosphonic acid comprising at least one group of the structure 
       
         
           
           
               
               
           
         
       
       wherein R 1  comprises an alkyl, an aryl, an alkoxide, an ester, and/or an ether. 
     
     
         7 . The system of any of  claims 1  to  5   claim 1 , wherein the organophosphonate compound comprises a phosphoric acid or a phosphonic acid comprising the structure 
       
         
           
           
               
               
           
         
       
       wherein R 2  comprises an alkyl, an aryl, an alkoxide, an ester, and/or an ether and R 3  comprises a hydrogen, an alkyl, an aryl, an alkoxide, an ester, an ether, and/or an epoxy. 
     
     
         8 . The system of  claim 1 , wherein the organophosphate compound and/or the organophosphonate compound are present in an amount of 1 percent by weight to 20 percent by weight based on total weight of the pretreatment composition. 
     
     
         9 . The system of  claim 1 , wherein the pretreatment composition further comprises a Group IVB metal. 
     
     
         10 . The system of  claim 9 , wherein the Group IVB metal is present in an amount of 1 ppm to 800 ppm based on total weight of the pretreatment composition. 
     
     
         11 . The system of  claim 1 , wherein the pretreatment composition further comprises free fluoride. 
     
     
         12 . (canceled) 
     
     
         13 . The system of  claim 1 , further comprising a film-forming composition. 
     
     
         14 . (canceled) 
     
     
         15 . A method of treating a substrate comprising:
 contacting at least a portion of a surface of the substrate with the cleaner or the solvent of the system of  claim 1 ; and contacting at least a portion of the surface with the pretreatment composition of  claim 1 ; wherein the substrate comprises magnesium or a magnesium alloy.   
     
     
         16 . The method of  claim 15 , further comprising rinsing the surface with water between contacting the substrate surface with the cleaning composition or the solvent and contacting the substrate surface with the pretreatment composition. 
     
     
         17 . The method of  claim 15 , wherein the surface is not contacted with a surface treatment composition prior to contacting with the pretreatment composition. 
     
     
         18 . (canceled) 
     
     
         19 . The method of  claim 15 , further comprising contacting the substrate surface with the film-forming composition following the contacting with the pretreatment composition. 
     
     
         20 . A magnesium substrate, wherein (a) oxygen and magnesium are present between an air/substrate interface and 500 nm below the air/substrate interface in a combined amount of at least 70 atomic % as measured by XPS depth profiling using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV and a concentric hemispherical analyzer; (b) carbon is present between an air/substrate interface and 500 nm below the air/substrate interface in an amount of no more than 30 atomic % as measured by XPS depth profiling using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV and a concentric hemispherical analyzer; and/or (c) fluoride is present between an air substrate interface and 500 nm below the air/substrate interface in an amount of no more than 8 atomic % as measured by XPS depth profiling using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV and a concentric hemispherical analyzer. 
     
     
         21 . A treated substrate, wherein at least a portion of the substrate is treated with the system of  claim 1 , wherein the substrate comprises magnesium or a magnesium alloy. 
     
     
         22 . The substrate of  claim 21 , wherein (a) oxygen and magnesium are present between an air/substrate interface and 500 nm below the air/substrate interface in a combined amount of at least 70 atomic % as measured by XPS depth profiling using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV and a concentric hemispherical analyzer; (b) carbon is present between an air/substrate interface and 500 nm below the air/substrate interface in an amount of no more than 30 atomic % as measured by XPS depth profiling using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV and a concentric hemispherical analyzer; and/or (c) fluoride is present between an air substrate interface and 500 nm below the air/substrate interface in an amount of no more than 8 atomic % as measured by XPS depth profiling using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV and a concentric hemispherical analyzer. 
     
     
         23 . The substrate of  claim 21 , wherein the substrate comprises a vehicle, a part, an article, a heat exchanger, an appliance, a personal electronic device, a multi-metal article, or combinations thereof. 
     
     
         24 . The substrate of  claim 23 , wherein the vehicle comprises an automobile or an aircraft. 
     
     
         25 . The substrate of  claim 21 , wherein the substrate comprises a three-dimensional component formed by an additive manufacturing process. 
     
     
         26 . (canceled)