Method for Local Alitation, Siliconization or Chromation of Metal Components

Abstract

A method for the production of a locally limited diffusion layer on a metal component is disclosed. In an embodiment, the method includes the steps of application of a paste containing Cr, Si and/or Al, and containing activators, to the areas of the metal component to be coated. The paste is solidified to form a donor pack. The regions which are not to be coated and are adjacent to the donor pack are covered with a diffusion-blocking powder pack. The component is heated to a temperature above 900° C. in order to carry out the alitation, siliconization and/or chromation. The method can be used in the production of turbine rotors.

1 - 8 . (canceled)  
   
   
       9 . A method for production of a locally limited diffusion layer on a metal: component by alitation, siliconization and/or chromation, comprising the steps of: 
 applying a paste containing Cr, Si and/or Al, and containing an activator, to an area of the metal component to be coated;    solidifying the paste to form a donor pack;    covering of a region, which is not to be coated and is adjacent to the donor pack, with a diffusion-blocking powder pack; and    heating to a temperature above 900° C. in order to carry out the alitation, siliconization and/or chromation.    
   
   
       10 . The method of  claim 9 , wherein the metal component is covered before the step of applying the paste, at least in the area to be coated, with a porous separating layer containing Al 2 O 3 .  
   
   
       11 . The method of  claim 9 , wherein the diffusion-blocking powder pack contains a metal powder having a similar or a same composition as the metal component to be coated.  
   
   
       12 . The method of  claim 9 , wherein the diffusion-blocking powder pack consists of Ni or of a Ni alloy.  
   
   
       13 . The method of  claim 9 , wherein the diffusion-blocking powder pack contains an activator.  
   
   
       14 . The method of  claim 9 , wherein the diffusion-blocking powder pack, the paste and/or the donor pack contains an activator in an amount of 0.2 to 5 wt. %.  
   
   
       15 . The method of  claim 9 , wherein the activator is NH 4 F, NH 4 Cl and/or AlF 3 .  
   
   
       16 . The method of  claim 9 , wherein the metal component is a component of a turbine rotor.