Grain orientation control through hot pressing techniques

Abstract

Systems and methods for electrical component, e.g., brush, manufacture are provided that control grain orientation. The systems and methods utilize hot pressing techniques to enhance the properties and functionalities of the electrical components/brushes. An intermediate work product characterized by a grain orientation is initially formed through a conventional pressing technique. The conventionally-pressed intermediates are positioned within a cavity/die with the grain orientation in a predetermined orientation relative to the hot press force to be applied thereto. The hot pressed final product exhibits superior resistivity, strength and apparent density/durability. Surface features may be formed on the face(s) of the final work product during the hot pressing step that cannot be achieved in conventional processing techniques. Multi-layered assemblies are provided that may be cross-linked or inter-bonded along an interface therebetween. Advantageous articles of manufacture, e.g., brushes and brush assemblies, are also disclosed.

1 . A method for fabricating a multi-layer brush, comprising: 
 a. providing a first powder mixture;    b. pressing the first powder mixture to form an intermediate work product characterized by a grain orientation that is perpendicular to an axis defined by force application during said pressing;    c. providing a second work product    d. positioning the intermediate work product in a cavity with the grain orientation in a predetermined alignment relative to a force axis to be applied to the cavity;    e. positioning the second work product adjacent the intermediate work product; and    f. hot pressing the intermediate work product and the second work product to form a multi-layer final work product.    
   
   
       2 . A method according to  claim 1 , wherein the first powder mixture includes at least one of carbon and copper.  
   
   
       3 . A method according to  claim 1 , wherein the intermediate work product is characterized by a specific resistivity, break strength and apparent density.  
   
   
       4 . A method according to  claim 3 , wherein the intermediate work product defines a first region of the multi-layer final work product, and wherein the first region is characterized by (i) a specific resistivity that is less than the specific resistivity of the intermediate work product; (ii) a break strength that is greater than the break strength of the intermediate work product; and (iii) an apparent density that is greater than the apparent density of the intermediate work product.  
   
   
       5 . A method according to  claim 1 , wherein the intermediate work product is oriented in the hot pressed cavity such that the grain orientation is independent of the force axis.  
   
   
       6 . A method according to  claim 5 , wherein the intermediate work product is oriented in the cavity such that the grain orientation defines a circumferential or axial grain orientation after hot pressing.  
   
   
       7 . A method according to  claim 1 , wherein the intermediate work product is oriented in the cavity such that the grain orientation defines a tangential grain orientation after hot pressing.  
   
   
       8 . A method according to  claim 1 , wherein the second work product is formed by (i) providing a second powder mixture; and (ii) pressing the second powder mixture to form a second intermediate work product characterized by a grain orientation that is perpendicular to an axis defined by force application during said pressing.  
   
   
       9 . A method according to  claim 8 , wherein each of the first and second intermediate work products include one or more materials that are adapted to cross-link or inter-bond during hot-pressing.  
   
   
       10 . A method according to  claim 9 , wherein the first and second intermediate work products form chemical bonds along or in proximity to an interface therebetween.  
   
   
       11 . A method according to  claim 1 , wherein the final work product is a multi-layer brush assembly.  
   
   
       12 . A method according to  claim 1 , wherein the cavity is adapted to form at least one surface feature on a face of the final work product during hot pressing.  
   
   
       13 . A method according to  claim 12 , wherein the at least one surface feature is formed on an end face of the final work product and is non-planar.  
   
   
       14 . A final work product fabricated according to the method of  claim 1 .  
   
   
       15 . A molded multi-layered brush, comprising: 
 at least two intermediate work products joined to each other along an interface,    wherein each of the intermediate work products defines an internal grain orientation;    wherein orientations of the internal grain orientations of the at least two intermediate work products are independent of each other and independent of the interface.    
   
   
       16 . A molded multi-layer brush according to  claim 15 , wherein the at least two intermediate work products are joined along the interface at least part based on cross-linking or inter-bonding therebetween.  
   
   
       17 . A molded multi-layer brush according to  claim 15 , wherein three intermediate work products are joined to each other, thereby defining two interfaces that are substantially parallel to each other.  
   
   
       18 . A molded multi-layer assembly, comprising: 
 an intermediate work defining an internal grain orientation; and    a second work product joined to the intermediate work product along an interface therewith;    wherein the internal grain orientation of the intermediate work product is independent of the second work product and independent of the interface.    
   
   
       19 . A molded multi-layer assembly according to  claim 18 , wherein the second work product is a second intermediate work product defining a second grain orientation.  
   
   
       20 . A molded multi-layer assembly according to  claim 18 , wherein the intermediate work product and the second work product are joined along the interface at least in part based on cross-linking or inter-bonding therebetween.