Wear resistant coating

Abstract

A wear resistant coating and a method of forming a wear resistant coating on a substrate. The method includes applying a plurality of round particles to the substrate, each of the plurality of round particles including a round outer layer encapsulating a wear resistant element. The method comprises applying a wear resistant coating binder to the substrate. The method includes heating the plurality of round particles and the wear resistant coating binder.

1 . A thermal spray powder, comprising:
 a first plurality of round particles, each of the plurality of round particles including:
 a wear-resistant element; 
 an intermediate coating metallurgically bonded to, and encapsulating, the wear-resistant element, the intermediate coating comprising titanium and defining a thickness that is in a range of 1-2 microns; and 
 a semi-porous outer layer encapsulating the intermediate coating and the wear-resistant element, the outer layer comprising a composite material that includes tungsten carbide and a sintering aid, the semi-porous outer layer having a density that is greater than a density of the wear-resistant element, and that is greater than 6 gm/cm 3 ; and 
   a binder material in powder form, the binder material comprising a plurality of metallic particles metallurgically bondable to the intermediate coating and the semi-porous outer layer.   
     
     
         2 . The thermal spray powder of  claim 1 , wherein the sintering aid is selected from the group consisting of cobalt, nickel and iron. 
     
     
         3 . The thermal spray powder of  claim 1 , wherein the composite material of the outer layer comprises 50% tungsten carbide and 50% of the sintering aid, by weight. 
     
     
         4 . The thermal powder of  claim 1 , wherein a diameter of each of the first plurality of round particles is within a range of 70% to 130% of a mean diameter of the first plurality of round particles so as to enable arranging the first plurality of round particles in a close packed structure. 
     
     
         5 . The thermal spray powder of  claim 1 , further comprising a second plurality of round particles, the second plurality of round particles having a mean diameter that is less than a mean diameter of the first plurality of round particles. 
     
     
         6 . The thermal spray powder of  claim 1 , wherein a volume fraction of the plurality of round particles within the thermal spray powder is within a range of 0.05 to 0.85. 
     
     
         7 . The thermal spray powder of  claim 1 , wherein each of the first plurality of round particles has an elastic modulus greater than 200 GPa. 
     
     
         8 . A method of manufacturing the thermal spray powder of  claim 1 , comprising depositing a coating material comprising titanium on the plurality of wear-resistant elements and mixing the coated wear-resistant elements with tungsten carbide powder and the sintering aid. 
     
     
         9 . The method of manufacturing the thermal spray powder of  claim 8 , wherein particles of the tungsten carbide powder have a Fisher sub sieve size of 1 μm and particles of the sintering aid have a Fisher sub sieve size of 1.2 μm. 
     
     
         10 . The method of manufacturing the thermal spray powder of  claim 8 , further comprising mixing the coated wear-resistant elements, the tungsten carbide powder and the sintering aid with a binding agent while spraying the mixture of the coated wear-resistant elements, tungsten carbide powder, sintering aid and the binding agent with water to form the round particles. 
     
     
         11 . A method of manufacturing the thermal spray powder of  claim 1 , comprising forming the semi-porous outer layer on the intermediate coating by heating the cermet and the sintering aid, thereby causing softening of the sintering aid and bridging of the sintering aid to the cermet, without fully densifying the composition of the cermet and the sintering aid, thereby forming internal voids in the outer layer, such that the outer layer is semi-porous. 
     
     
         12 . The method of manufacturing the thermal spray powder of  claim 11 , wherein heating the cermet and the sintering aid causing softening of the sintering aid and bridging of the sintering aid to the cermet, without fully densifying the composition of the cermet and the sintering aid comprises heating the wear-resistant element coated with the intermediate coating and the composite material to a first temperature over a first predetermined period of time, followed by maintaining a temperature of the wear-resistant element coated with the intermediate coating and the composite material at the first temperature for a second predetermined period of time, followed by raising the temperature of the wear-resistant element coated with the intermediate coating and the composite material to a second temperature that is higher than the first temperature, over a third predetermined period of time, followed by cooling the wear-resistant element coated with the intermediate coating and the composite material. 
     
     
         13 . The method of manufacturing the thermal spray power of  claim 12 , wherein the first temperature is 500° C. and the second temperature is 850° C. 
     
     
         14 . The method of manufacturing the thermal spray powder of  claim 13 , wherein the first predetermined period of time is at least 60 minutes, the second predetermined period of time is approximately 30 minutes, and the third predetermined period of time is at least 180 minutes. 
     
     
         15 . A wear-resistant coating comprising the thermal spray powder of  claim 1 . 
     
     
         16 . A method of forming the wear-resistant coating of  claim 15  on a substrate using a torch. 
     
     
         17 . The method of  claim 16 , comprising using a plasma transferred arc (PTA) torch or an oxygen-fuel torch to apply the thermal spray powder to the substrate to form the wear-resistant coating. 
     
     
         18 . The method of  claim 17 , wherein the torch comprises an oxygen-fuel torch, and the method comprises applying the thermal spray powder using a high-velocity oxy-fuel deposition (HVOF) process. 
     
     
         19 . The method of  claim 16 , comprising the steps of:
 directing a flame of the torch to a surface of the substrate;   introducing the thermal spray powder into the flame of the torch via a stream of gas,   causing a temperature of the thermal spray powder temperature to be above an adhesion temperature of the thermal spray powder, thereby causing the thermal spray powder to adhere to the surface of the substrate and form a green coating.   
     
     
         20 . The method of  claim 19 , further comprising heating the green coating after forming the green coating to raise a temperature of the binder material above a melting temperature of the binder material to form a fluid that flows over the surface of the substrate.