Process for diffusing a substrate into a base material

Abstract

An improved process for diffusing a substrate into a base material is described. Generally, a process is provided for introducing a base material into a salt bath having a substrate with a catalyst. A select amount of catalyst and desired salt bath temperature are provided sufficient to lower the activation energy of the base material such that the substrate is able to easily diffuse into the surface of the base material. Nevertheless, certain substances within the base material may inhibit the diffusion of the substrate into the surface of the base material. Accordingly, a select amount of catalyst and desired salt bath temperature are further provided sufficient to promote leaching of such select substances that inhibit the diffusion of such substrate into such base material. The leached substances are substantially replaced by the diffused substrate.

1 . A method for diffusing a substrate and nitride into a base material comprising:
 providing a base material having at least one substance which inhibits diffusion of the substrate into said base material,   providing a salt bath which includes sodium carbonate and a salt selected from the group consisting of sodium cyanate and potassium cyanate;   dispersing a select amount of substrate and a select amount of catalyst in said bath, wherein the select amount of catalyst is sufficient to lower the activation energy of the base material and promote leaching of the substance which inhibits diffusion of the substrate into said base material;   heating the salt bath to a temperature sufficient to lower the activation energy of the base material and promote leaching of the substance which inhibits diffusion of the substrate into said base material; and   soaking the base material in the salt bath for a time sufficient to diffuse the substrate into said base material to substantially replace the leached substance with the substrate while preventing distortion or warping of the base material.   
     
     
         2 . A method for diffusing titanium and nitride into a base material comprising:
 providing a base material having at least one substance which inhibits diffusion of titanium into said base material,   providing a salt bath which includes sodium carbonate and a salt selected from the group consisting of sodium cyanate and potassium cyanate;   dispersing a select amount of titanium formed by electrolysis of a titanium compound in said bath, wherein the select amount of electrolyzed titanium is sufficient to lower the activation energy of the base material and promote leaching of the substance which inhibits diffusion of the titanium into said base material;   heating the salt bath to a temperature sufficient to lower the activation energy of the base material and promote leaching of the substance which inhibits diffusion of the titanium into said base material; and   soaking the base material in the salt bath for a time sufficient to diffuse the titanium into said base material to substantially replace the leached substance with the titanium while preventing distortion or warping of the base material.   
     
     
         3 . A method for diffusing titanium and nitride into a 300 series stainless steel base material comprising:
 providing a 300 series stainless steel base material having a chromium content which inhibits diffusion of titanium into said base material,   providing a salt bath which includes sodium carbonate and a salt selected from the group consisting of sodium cyanate and potassium cyanate;   dispersing about 40 micrograms to about 60 micrograms of electrolyzed titanium is dispersed in the salt bath such that a concentration of from about 0.005% to about 0.010% of electrolyzed titanium in the salt bath is achieved, wherein the amount of electrolyzed titanium is sufficient to lower the activation energy of the base material and promote leaching of the chromium which otherwise inhibits diffusion of the titanium into said base material;   heating the salt bath to a temperature over 590 degrees C. sufficient to lower the activation energy of the base material and promote leaching of the chromium; and   soaking the 300 series stainless steel base material in the salt bath for about 10 to 90 minutes to diffuse the titanium into said 300 series stainless steel base material to substantially replace the leached chromium with the titanium while preventing distortion or warping of the 300 series stainless steel base material.   
     
     
         4 . The method of  claim 3  wherein the soaking temperature is from about 600 degrees C. to about 620 degrees C. 
     
     
         5 . The method of  claim 3  wherein the soaking time is from about 10 minutes to about 20 minutes. 
     
     
         6 . A method for diffusing titanium and nitride into a 400 series stainless steel base material comprising:
 providing a 400 series stainless steel base material having a chromium content which inhibits diffusion of titanium into said base material, the 400 series stainless steel base material further having a select core hardness;   providing a salt bath which includes sodium carbonate and a salt selected from the group consisting of sodium cyanate and potassium cyanate;   dispersing about 40 micrograms to about 60 micrograms of electrolyzed titanium is dispersed in the salt bath such that a concentration of from about 0.005% to about 0.010% of electrolyzed titanium in the salt bath is achieved, wherein the amount of electrolyzed titanium is sufficient to lower the activation energy of the base material and promote leaching of the chromium which otherwise inhibits diffusion of the titanium into said base material;   heating the salt bath to a temperature over 430 degrees C. sufficient to lower the activation energy of the base material and promote leaching of the chromium, and maintain the original tempering conditions of the 400 series base material; and   soaking the 400 series stainless steel base material in the salt bath for about 10 to 90 minutes to diffuse the titanium into said 400 series stainless steel base material to substantially replace the leached chromium with the titanium while preventing distortion or warping of the 400 series stainless steel base material.   
     
     
         7 . The method of  claim 6  wherein the soaking temperature is from about 430 degrees C. to about 500 degrees C. 
     
     
         8 . The method of  claim 6  wherein the soaking time is from about 10 minutes to about 30 minutes. 
     
     
         9 . A method for diffusing titanium and nitride into a 300 series stainless steel base material comprising:
 providing a 300 series stainless steel base material having a chromium content which inhibits diffusion of titanium into said base material, the 300 series stainless steel base material further having a select core hardness;   providing a salt bath which includes sodium carbonate and a salt selected from the group consisting of sodium cyanate and potassium cyanate;   dispersing about 40 micrograms to about 60 micrograms of electrolyzed titanium is dispersed in the salt bath such that a concentration of from about 0.005% to about 0.010% of electrolyzed titanium in the salt bath is achieved, wherein the amount of electrolyzed titanium is sufficient to lower the activation energy of the base material and promote leaching of the chromium which otherwise inhibits diffusion of the titanium into said base material;   heating the salt bath to a temperature over 680 degrees C. sufficient to lower the activation energy of the base material and promote leaching of the chromium; and   soaking the 300 series stainless steel base material in the salt bath for about 10 to 30 minutes to diffuse the titanium into said 300 series stainless steel base material to substantially replace the leached chromium with the titanium while preventing distortion or warping of the 300 series stainless steel base material.   
     
     
         10 . The method of  claim 9  wherein the soaking temperature is from about 680 degrees C. to about 700 degrees C. 
     
     
         11 . The method of  claim 9  wherein the soaking time is from about 10 minutes to about 30 minutes. 
     
     
         12 . A method for diffusing titanium and nitride into a series stainless steel base material and polishing the resulting diffused base material, comprising:
 providing a stainless steel base material having a chromium content which inhibits diffusion of titanium into said base material, the stainless steel base material further having a select core hardness;   providing a salt bath which includes sodium carbonate and a salt selected from the group consisting of sodium cyanate and potassium cyanate;   dispersing electrolyzed titanium in the salt bath sufficient to lower the activation energy of the base material and promote leaching of the chromium which inhibits diffusion of the titanium into said base material;   heating the salt bath to a temperature sufficient to lower the activation energy of the base material and promote leaching of the chromium;   soaking the stainless steel base material in the salt bath to diffuse the titanium into said stainless steel base material to substantially replace the leached chromium with the titanium while preventing distortion or warping of the stainless steel base material; and   polishing the base material after diffusion of the titanium.   
     
     
         13 . The method of  claim 12  wherein the base material is polished using a chromium oxide polishing compound. 
     
     
         14 . The method of  claim 13  wherein the chromium oxide polishing compound has a particle size of less than  2  micrometers. 
     
     
         15 . The method of  claim 13  wherein the chromium oxide polishing compound has a particle size of from about 0.5 to about 1 micrometer. 
     
     
         16 . The method of  claim 12  wherein the base material is polished using a cotton domet flannel type polishing wheel at a polishing speed from about 3000 rpm to about 5000 rpm. 
     
     
         17 . The method of  claim 16  wherein the polishing speed is from about 3500 rpm to about 4500 rpm.