Carbide wear surface and method of manufacture

Abstract

A radial bearing having a wear surface with improved wear characteristics comprises a steel support, to which is bonded a metal carbide composite wear surface made by first arranging, within a cavity defined between a steel mold and the steel support, tiles made of microwave sintered, cemented metal carbide, closely packing the voids between the tiles with metal carbide powder, and infiltrating the mold cavity with a metal brazing alloy by subjecting the filled mold to rapid heating. The brazing alloy fills voids between the metal carbide particles, the microwave sintered metal carbide tiles, and the metal support, thereby relatively rapidly consolidating the carbide into a wear layer bonded with the steel support without substantially damaging the properties of the microwave-sintered metal carbide tiles.

What is claimed is: 
     
         1 . A method of forming a wear layer on an article, the article comprising at least in part a steel support having a surface on which the wear layer is formed, comprising;
 arranging in a cavity formed between a mold and the surface of a support on which the wear layer will be formed, an array of tiles made of microwave sintered metal carbide composite;   filling voids between the tiles, the mold and the support with metal carbide powder to form a matrix comprising the tiles and the spherical metal carbide powder;   heating the brazing alloy to cause a brazing alloy to melt and infiltrate the matrix, heating comprising placing the mold containing the matrix, the bearing support, and unmelted brazing alloy with flux in an induction furnace and operating the induction furnace for a period of time sufficient to allow the brazing alloy to melt and uniformly infiltrate the matrix without damaging the tiles;   allowing the matrix to cool, thereby forming a consolidation of the microwave sintered metal carbide tiles and the particles of metal carbide on the bearing support, the consolidation comprising the wear surface; and   removing the mold and finishing the wear surface.   
     
     
         2 . The method of  claim 1 , wherein the microwave sintered metal carbide tiles are substantially uniform in shape and dimensions over at least a portion of the wear surface. 
     
     
         3 . The method of  claim 1 , wherein the mold and support are made of steel. 
     
     
         4 . The method of  claim 1 , wherein the mold with the matrix and support is heated for less than an hour. 
     
     
         5 . The method of  claim 1 , wherein the mold with the matrix and support is heated to a temperature of approximately 1000 degrees Celsius (C.) in an air atmosphere. 
     
     
         6 . The method of  claim 1 , wherein the tiles are comprised of microwave sintered tungsten carbide, cemented with a cobalt alloy, and wherein the particles of metal carbide are comprised of spherical tungsten carbide. 
     
     
         7 . The method of  claim 1 , wherein the support is part of a radial bearing. 
     
     
         8 . The method of  claim 7 , wherein the support is part of a mandrel that cooperates with the mold to form a funnel into which brazing alloy is placed prior to heating. 
     
     
         9 . The method of  claim 1 , wherein the metal carbide powder is comprised of particles of metal carbide are of a spherical type and have a size of 25 to 500 microns. 
     
     
         10 . The method of  claim 9 , wherein the metal carbide is tungsten carbide. 
     
     
         11 . The method of  claim 1 , further comprising affixing at least one row of tiles to the surface of the mandrel support and then assembling the support and the mold to form the cavity. 
     
     
         12 . An article having at least one wear surface, the article comprising a steel support with a surface and a wear layer bonded to the surface, the wear layer functioning as the at least one wear surface of the article and being comprised of a consolidation, in brazing alloy, of a matrix comprised of a plurality of microwave-sintered, metal carbide tiles in a closely spaced arrangement and metal carbide powder filling voids between the tiles. 
     
     
         13 . The article of  claim 12 , wherein the article is a radial bearing. 
     
     
         14 . The article of  claim 12 , wherein the article is comprised of an inner radial bearing and an outer radial bearing, the steel support forming part of one of the inner radial bearing or the outer radial bearing. 
     
     
         15 . The article of  claim 12 , wherein the microwave-sintered metal carbide is comprised of cemented tungsten carbide, and wherein the metal carbide powder is comprised of tungsten carbide particles. 
     
     
         16 . The article of  claim 15 , wherein the tungsten carbide particles are generally spherical shaped. 
     
     
         17 . The article of  claim 12 , wherein the metal carbide particles are generally spherically shaped. 
     
     
         18 . An article having at least one wear surface, the article comprising a support with a surface and a wear layer bonded to the surface, the wear layer functioning as the at least one wear surface of the article and being comprised of a consolidation, in brazing alloy, of a matrix comprised of a plurality of microwave-sintered, metal carbide tiles in a closely spaced arrangement and metal carbide powder filling voids between the tiles, wherein the wear layer bonded to the steel support is a product of a process comprising:
 arranging in a cavity formed between a mold and the surface of the support on which the wear layer will be formed, an array of tiles made of microwave-sintered metal carbide composite;   filling voids between the tiles, the mold and the support with metal carbide powder to form a matrix comprising the tiles and the metal carbide powder;   heating the brazing alloy to cause a brazing alloy to melt and infiltrate the matrix, heating comprising placing the mold containing the matrix, the support, and unmelted brazing alloy in an induction furnace and operating the induction furnace for a period of time sufficient to allow the brazing alloy to melt and uniformly infiltrate the matrix without damaging the tiles;   allowing the matrix to cool, thereby forming a consolidation of the microwave-sintered metal carbide tiles and the spherical particles of metal carbide on the support, the consolidation comprising the wear surface; and   removing the mold and finishing the wear surface.   
     
     
         19 . The article of  claim 18 , wherein the mold and the support are made of steel. 
     
     
         20 . The article of  claim 18 , wherein the mold with the matrix and support is heated for less than an hour. 
     
     
         21 . The article of  claim 18 , wherein the mold with the matrix and steel support is heated to a temperature of approximately 1000 degrees Celsius (C.) in an air atmosphere. 
     
     
         22 . The article of  claim 18 , wherein the metal carbide powder is spherical metal carbide powder. 
     
     
         23 . The article of  claim 22 , wherein the metal carbide is tungsten carbide. 
     
     
         24 . The article of  claim 18 , wherein the microwave-sintered metal carbide tiles are comprised of microwave-sintered tungsten carbide cemented with a cobalt alloy.