Anodization process and layers produced therefrom

Abstract

A multi-step anodization process is disclosed for forming a barrier layer on a photoreceptor substrate. The process produces layers in relatively short periods of time. Also disclosed is a preheating operation that produces a relatively hard anodized layer. The preheating operation can be used in conjunction with either of the multi-step anodization process, or with conventional processes.

1 . A process for forming a barrier layer on a photoreceptor substrate by organic acid anodization, the process comprising: 
 providing a photoreceptor substrate;    providing an organic acid electrolyte;    applying a multi-step voltage profile to the photoreceptor substrate in contact with the electrolyte, wherein the profile includes a first step in which a first voltage is applied for a first time period and a second step in which a second voltage, less than the first voltage is applied for a second time period.    
     
     
         2 . The process of  claim 1  wherein the second voltage is from about 50% to about 20% of the first voltage.  
     
     
         3 . The process of  claim 1  wherein the second voltage is from about 40% to about 30% of the first voltage.  
     
     
         4 . The process of  claim 1  wherein the sum of the first time period and the second time period is less than 5 minutes.  
     
     
         5 . The process of  claim 1  wherein the sum of the first time period and the second time period is less than 1 minute.  
     
     
         6 . The process of  claim 1  wherein the profile includes a third step in which a third voltage, less than the second voltage, is applied for a third time period.  
     
     
         7 . The process of  claim 6  wherein the third voltage is from about 30% to about 20% of the second voltage.  
     
     
         8 . The process of  claim 6  wherein the second voltage is from about 40% to about 30% of the first voltage.  
     
     
         9 . The process of  claim 6  wherein the sum of the first time period, the second time period, and the third time period is less than 5 minutes.  
     
     
         10 . The process of  claim 6  wherein the sum of the first time period, the second time period, and the third time period is less than 1 minute.  
     
     
         11 . The process of  claim 1  wherein the first step employs a voltage from about 20 to about 24 volts and the second step employs a voltage from about 12 to about 17 volts.  
     
     
         12 . The process of  claim 6  wherein the first step employs a voltage from about 22 to about 26 volts, the second step employs a voltage from about 14 to about 18 volts, and the third step employs a voltage from about 10 to about 14 volts.  
     
     
         13 . The process of  claim 1  further comprising: 
 prior to applying the multi-step voltage profile, subjecting the photoreceptor to a heating operation in which the photoreceptor is subjected to a temperature of from about 450° C. to about 650° C.    
     
     
         14 . The process of  claim 13  wherein the photoreceptor is subjected to a temperature of about 550° C.  
     
     
         15 . The substrate and barrier layer produced by the method of  claim 1 .  
     
     
         16 . A process for forming a barrier layer on a photoreceptor substrate by organic acid anodization, the process comprising: 
 providing a photoreceptor substrate;    providing an organic acid electrolyte;    heating the photoreceptor substrate to a temperature of from about 450° C. to about 650° C.;    contacting the photoreceptor substrate with the electrolyte;    applying a voltage to the photoreceptor substrate in contact with the electrolyte for a period of time so as to form an anodized layer thereon.    
     
     
         17 . The process of  claim 16  wherein the temperature is about 550° C.  
     
     
         18 . The process of  claim 16  wherein the heating is performed for a time period of from about 10 seconds to about 60 seconds.  
     
     
         19 . The process of  claim 16  wherein the applying a voltage is performed by applying a multi-step voltage profile to the photoreceptor substrate, wherein the profile includes a first step in which a first voltage is applied for a first time period and a second step in which a second voltage, less than the first voltage is applied for a second time period.  
     
     
         20 . The substrate and barrier layer produced by the method of  claim 16.