Methods for enhancing a surface of a downhole tool and downhole tools having an enhanced surface

Abstract

A downhole tool having a layer of wear resistant material applied thereon utilizing a thermal spray process and methods of manufacturing such downhole tools.

1 . A method for manufacturing a downhole tool comprising:
 providing a tool body having a surface;   applying a first intermediate layer to at least a portion of the surface of the tool body;   applying a layer of a first wear resistant material utilizing a thermal spray process over at least a portion of the first intermediate layer; and   sintering the layer of wear resistant material, wherein the first intermediate layer is formed of a material having a melting temperature that is less than the melting temperature of the first wear resistant material.   
     
     
         2 . The method of  claim 1 , wherein the first intermediate layer comprises a second wear resistant material. 
     
     
         3 . The method of  claim 2 , wherein the second wear resistant material is applied using a non-thermal spray process. 
     
     
         4 . The method of  claim 1 , wherein the first intermediate layer comprises a first buffer material. 
     
     
         5 . The method of  claim 1 , wherein the buffer material comprises a metal component selected from the group consisting of a metal, a metal alloy, a metal boride, a metal phosphate, and combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the first intermediate layer comprises a first hardfacing composition. 
     
     
         7 . The method of  claim 1 , wherein the thermal spray process is selected from the group consisting of a high velocity oxygen fuel process, a detonation gun process, and a super detonation gun process. 
     
     
         8 . The method of  claim 7 , wherein the thermal spray process is a high velocity oxygen fuel spray process. 
     
     
         9 . The method of  claim 1 , wherein the first wear resistant material comprises hard particles and a binder, and wherein the hard particles are selected from the group consisting of carbides, borides, nitrides, and carbonitrides of W, Ti, Mo, Nb, V, Hf, Ta, and Cr, and wherein the binder is selected from the group consisting of cobalt, nickel, iron, mixtures, and alloys thereof. 
     
     
         10 . The method of  claim 9 , wherein the hard particles further comprise one or more of boronitrides; diamond; and refractory metals. 
     
     
         11 . The method of  claim 9 , wherein the hard particles comprise mono-tungsten carbide and the binder comprises cobalt. 
     
     
         12 . The method of  claim 1 , wherein the layer of the first wear resistant material has a hardness of at least 80 Ra. 
     
     
         13 . The method of  claim 1 , wherein the melting temperature of the material of the first intermediate layer differs from the melting temperature of the first wear resistant material by at least 50° C. 
     
     
         14 . The method of  claim 1 , wherein the melting temperature of the material of the first intermediate layer differs from the melting temperature of the first wear resistant material by at least 100° C. 
     
     
         15 . The method of  claim 1 , wherein the material of the first intermediate layer comprises a metal alloy selected from the group consisting of an iron-based alloy, an aluminum-based alloy, a nickel-based alloy, a cobalt-based alloy, a copper-based alloy, and combinations thereof. 
     
     
         16 . The method of  claim 1 , wherein the material of the first intermediate layer comprises a nickel-based metal alloy. 
     
     
         17 . The method of  claim 16 , wherein the material of the first intermediate layer further comprises hard particles. 
     
     
         18 . The method of  claim 1 , wherein the surface of the tool body onto which the first intermediate layer is applied has a non-planar surface. 
     
     
         19 . The method of  claim 1 , wherein the downhole tool is a roller cone drill bit comprising a cone which comprises a plurality of parent cutting elements spaced about the exterior surface of the body and the first intermediate layer and wear resistant layer are applied to at least a portion of at least one of the parent elements. 
     
     
         20 . The method of  claim 19 , wherein a first plurality of parent elements are arranged in a circumferential gage row and a second plurality of parent elements are arranged in one or more circumferential inner rows, and wherein the first plurality of parent elements in the gage row and the second plurality of parent elements in the inner rows comprise an intermediate layer and a layer of a wear resistant material sintered to at least a portion of the parent elements, and wherein the layer of wear resistant material in the gage row differs with respect to one or more properties from the layer of wear resistant material in the inner rows. 
     
     
         21 . The method of  claim 20 , wherein the one or more properties are selected from hardness, thickness, hard particle content, hard particle average grain size, toughness, composition, binder content, density, porosity, elastic modulus, microstructure, abrasion resistance, and erosion resistance. 
     
     
         22 . The method of  claim 1 , wherein the method further comprises applying a second intermediate layer comprising a third wear resistant material to at least a portion of the first intermediate layer, and wherein the second intermediate layer is positioned between the first intermediate layer and the wear resistant layer of the first wear resistant material, and wherein the second intermediate layer differs with respect to one or more properties from the first intermediate layer and the wear resistant layer of the first wear resistant material. 
     
     
         23 . The method of  claim 22 , wherein the third wear resistant material of the second intermediate layer provides a gradient in one or more properties between the first wear resistant material and the material of the first intermediate layer. 
     
     
         24 . The method of  claim 22 , wherein the third wear resistant material of the second intermediate layer provides an interruption in one or more properties between the first wear resistant material and the material of the first intermediate layer. 
     
     
         25 . The method of  claim 22 , wherein the method further comprises applying a third intermediate layer positioned between the second intermediate layer and the wear resistant layer of the first wear resistant material, and wherein the third intermediate layer is formed of a material having a melting temperature that is less than the melting temperature of the first wear resistant material and less than the melting temperature of the third wear resistant material. 
     
     
         26 . The method of  claim 4 , wherein the method further comprises applying a second intermediate layer comprising a third wear resistant material to at least a portion of the first intermediate layer and applying a third intermediate layer comprising a second buffer material to at least a portion of the second intermediate layer, and wherein the second intermediate layer is positioned between the first intermediate layer and the third intermediate layer which is positioned interior of the wear resistant layer of the first wear resistant material. 
     
     
         27 . The method of  claim 26 , wherein the first wear resistant material and the third wear resistant material are the same composition; and wherein the first buffer material and the second buffer material are the same composition. 
     
     
         28 . The method of  claim 1 , wherein the tool body further comprises a second intermediate layer positioned between the first intermediate layer and the wear resistant layer of the first wear resistant material, and wherein the second intermediate layer comprises a hardfacing composition having a metal content that is less than the metal content of the first intermediate layer and greater than the metal content of the wear resistant layer of the first wear resistant material. 
     
     
         29 . The method of  claim 1 , wherein the sintering process utilizes temperatures of at most 1200° C. 
     
     
         30 . The method of  claim 1 , wherein the sintering process utilizes pressures in the range of from 700 kPa to 11 MPa. 
     
     
         31 . The method of  claim 1 , wherein the material of the first intermediate layer has a melting temperature that is less than the tool body. 
     
     
         32 . A downhole tool comprising:
 a tool body having at least two layers applied on at least a portion of the surface of the tool body, wherein
 the at least two layers comprise a wear resistant layer and a first intermediate layer positioned between the surface of the tool body and the wear resistant layer, wherein 
 the wear resistant layer comprises a first wear resistant material which is applied utilizing a thermal spray process and sintered; and 
 the first intermediate layer is formed of a material having a melting temperature that is less than the melting temperature of the first wear resistant material.