Preparation for pre-treating surfaces by chemically converting oxide layers of titanium or titanium alloys

Abstract

A preparation and a process for the surface pretreatment of titanium or titanium alloys containing 200 to 400 g/l NaOH and 10 to 150 g/l MGDA in water, wherein the preparation has a pH of at least 12, and preferably 13.

1 - 14 . (canceled) 
     
     
         15 . A preparation for a surface pretreatment of titanium or titanium alloys containing 200 to 400 g/l NaOH and 10 to 150 g/l MGDA in water, wherein the preparation has a pH of at least 12. 
     
     
         16 . The preparation as claimed in  claim 15 , wherein the pH is at least 13. 
     
     
         17 . The preparation as claimed in  claim 15 , wherein a fluoride content is less than 0.001% by weight, based on fluoride present in the preparation used. 
     
     
         18 . The preparation as claimed in  claim 15 , wherein a content of NaOH is 300 to 375 g/l, and a content of MGDA is 30 to 100 g/l. 
     
     
         19 . The preparation as claimed in  claim 15 , comprising a content of polymeric thickeners. 
     
     
         20 . The preparation as claimed in  claim 19 , wherein the thickeners used comprise xanthan gum or agar-agar. 
     
     
         21 . The preparation as claimed in  claim 19 , wherein the thickeners are present in a concentration of 2 to 40 g/l. 
     
     
         22 . The preparation as claimed in  claim 21 , wherein the thickeners are present in a concentration of 10 to 15 g/l. 
     
     
         23 . The preparation as claimed in  claim 15 , wherein a content of further substances is less than 0.5 g/l. 
     
     
         24 . A process for a surface pretreatment of articles composed of titanium or titanium alloys, comprising
 contacting the articles composed of titanium or titanium alloys with a preparation containing 200 to 400 g/l NaOH and 10 to 150 g/l MGDA in water,   wherein a content of further substances is less than 1 g/l and a pH of the preparation is at least 12, for 5 to 60 minutes at 20 to 80° C.   
     
     
         25 . The process as claimed in  claim 24 , wherein the pH is at least 13. 
     
     
         26 . The process as claimed in  claim 24 , wherein a fluoride content is less than 0.001% by weight, based on fluoride present in the preparation used. 
     
     
         27 . The process as claimed in  claim 24 , wherein a content of NaOH is 300 to 375 g/l, and a content of MGDA is 30 to 100 g/l. 
     
     
         28 . The process as claimed in  claim 24 , wherein the contacting is effected by immersion. 
     
     
         29 . The process as claimed in  claim 24 , wherein the contacting is effected for 10 to 30 minutes at 40 to 70° C. 
     
     
         30 . The process as claimed in  claim 24 , wherein the contacting is effected for 20 minutes at 60° C. 
     
     
         31 . An article composed of titanium or titanium alloys obtained using a preparation as claimed in  claim 15 . 
     
     
         32 . An article composed of titanium or titanium alloys having a porous layer at a surface thereof, wherein pores of the porous surface are predominantly open, have a number-average pore size of less than 100 nm. 
     
     
         33 . The article as claimed in  claim 32 , wherein the number-average pore size is 30 to 70 nm. 
     
     
         34 . An aircraft comprising an article composed of titanium or titanium alloys as claimed in  claim 32 .