WEAR RESISTANT COATING
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.
The present application is a continuation of U.S. patent application Ser. No. 15/464,027, filed on Mar. 20, 2017, which is a continuation of U.S. patent application Ser. No. 14/504,212, filed Oct. 1, 2014, which claims priority to U.S. Provisional Patent Application No. 61/885,714, filed Oct. 2, 2013, and U.S. Provisional Patent Application No. 61/987,541, filed May 2, 2014, the disclosures of which are hereby incorporated by reference herein in their entirety.
TECHNICAL FIELDThe disclosure herein generally but not exclusively relates to a hardfacing powder for forming a wear resistant coating on a substrate, a method for making a hardfacing powder for forming a wear resistant coating on a substrate, a wear resisting coating on a substrate, and a method for forming a wear resistant coating on a substrate.
BACKGROUNDHardfacing is a process of forming a wear resistant coating on a surface to improve the wear properties of the surface or repair the surface. Hardfacing is currently used in relation to industrial, excavation and drilling tools, for example.
Generally, there is a long felt need for better, harder and more consistent wear resistant coatings that can be formed relatively easily.
SUMMARYDisclosed herein is a method of forming a wear resistant coating on a substrate, the method comprising the steps of:
applying a plurality of round particles to the substrate, each of the plurality of round particles comprising a round outer layer encapsulating a wear resistant element;
applying a wear resistant coating binder to the substrate; and
heating the plurality of round particles and the wear resistant coating binder.
An embodiment comprises the step of metallurgically bonding the wear resistant coating binder to at least one of an inner surface and an outer surface of the round outer layer of each of the plurality of round particles.
In an embodiment, the wear resistant coating binder comprising metallic binding material and the metallic binding material is melted to form a monolithic matrix of metallic binding material.
An embodiment comprises the step of the metallic binding material so melted penetrating the round outer layer of each of the plurality of round particles.
In an embodiment, the wear resistant element of each of the plurality of round particles has a coating metallurgically bonded thereto, and the coating is metallurgically bonded with the wear resistant coating binder.
An embodiment comprises the step of the binding material penetrating the round outer layer of each of the plurality of round particles and forming a metallurgical bond with the coating.
Generally, the round outer layer of each of the plurality of round particles controls the spacing and/or the packing of the wear resistant elements of the plurality of round particles within the wear resistant coating when formed. Consequently, the thickness of the round outer layer may be chosen to control the number of wear resistant elements per unit volume of the wear resistant coating. The thickness of the round outer layer may be chosen to control the wear resistant element's uniformity of distribution within the wear resistant coating.
In an embodiment, the step of heating may generally cause the wear resistant coating binder to bind the plurality of round particles. The heating may be at least one of during and after application of the wear resistant coating binder and the plurality of round particles. For example, the step of heating may comprise the step of heating the plurality of round particles so applied to the substrate and heating the wear resistant coating binder so applied to the substrate.
In an embodiment, the step of applying the plurality of round particles to the substrate comprises the step of introducing the plurality of round particles into a flame directed at the substrate. The flame may heat the plurality of round particles. The step of applying a wear resistant coating binder to the substrate may comprise the step of introducing the wear resistant coating binder into the flame directed at the substrate. The flame may heat the wear resistant coating binder. The plurality of round particles and the wear resistant coating binder may be, but not necessarily, introduced separately into the flame.
An embodiment comprises the step of introducing a mixture comprising the plurality of round particles and the wear resistant coating binder into a flame directed at the substrate. The flame may heat the plurality of round particles and the wear resistant coating binder.
In an embodiment, the flame heats the plurality of round particles and the wear resistant coating binder above an adhesion temperature.
In an embodiment, the flame is generated by a high velocity oxygen-fuel deposition torch.
An embodiment comprises applying the plurality of round particles and a wear resistant coating binder to the substrate by introducing the plurality of round particles and the wear resistant coating binder into a plasma stream directed at the substrate, the plasma stream heating the wear resistant coating binder and the plurality of round particles.
In an embodiment, the plasma stream heats the wear resistance coating binder to a temperature greater than at least one of a wear resistant coating binder softening temperature and a wear resistant coating binder melting temperature.
An embodiment comprises the step of introducing a mixture comprising the plurality of round particles and the wear resistant coating binder into a plasma stream directed at the substrate.
In an embodiment, the plurality of round particles and the wear resistant coating binder are separately introduced into a plasma stream directed at the substrate.
In an embodiment, the plurality of round particles and the wear resistant coating binder are deposited onto a melted portion of the substrate outside of a plasma stream that heated the melted portion. The melted portion of the substrate may heat the plurality of round particles and the wear resistant coating binder.
In an embodiment, the melted portion of the substrate heats the wear resistant coating binder to a temperature greater than at least one of a wear resistant coating binder softening temperature and a wear resistant coating binder melting temperature.
In an embodiment, the plurality of round particles and the wear resistant coating binder are separated from the plasma stream by a separator. The separator may comprises a separating structure. The separator may comprise a separating wall.
In an embodiment, the plasma stream is moved across a surface of the substrate and a source of the plurality of round particles and a source of the wear resistant coating binder follow the plasma stream. The plasma stream may be moved across a surface of the substrate and a source of the plurality of round particles and the wear resistant coating binder follow the plasma stream.
An embodiment comprises the step of delivering a shielding gas around the plasma stream.
In an embodiment, the wear resistant coating binder comprises a plurality of metallic particles.
In an embodiment, the wear resistant element comprises cubic boron nitride.
In an embodiment, the plurality of round particles has a close packed arrangement once so applied to the substrate.
Disclosed herein is a hardfacing powder for forming a wear resistant coating on a substrate. The hardfacing powder comprises a plurality of round particles, and a wear resistant coating binder for binding the plurality of round particles in the wear resistant coating when formed. Each of the plurality of round particles comprises a round outer layer encapsulating a wear resistant element.
In an embodiment, for each of the plurality of round particles the round outer layer has a density greater than that of the wear resistant element. The wear resistant coating binder is generally molten during formation of the wear resistant coating. The plurality of round particles are less buoyant in molten wear resistant coating binder than a plurality of wear resistant elements free of the round outer coatings. The distribution of the elements in the wear resistant coating may be consequently better than if the round outer layers were absent.
In an embodiment, the wear resistant coating binder may comprise a plurality of metallic particles. The plurality of metallic particles may comprise a braze metal. The braze metal may comprise a braze alloy.
In an embodiment, the volume fraction of the plurality of round particles is at least 0.05. The volume fraction of the plurality of round particles may be no more than 0.85.
In an embodiment, the wear resistant element of each of the plurality of round particles has an ISO 6106 mesh size of at least 18. The wear resistant element of each of the plurality of round particles may have an ISO 6106 mesh size of no more than 120. In an alternative embodiment, the wear resistant element of each of the plurality of round particles may have an ISO 6106 mesh size of no more than 80.
In an embodiment, the round outer layer comprises a composite material. The composite material may be a cermet. The cermet may be a polycrystalline cermet.
In an embodiment, the wear resistant element of each of the plurality of round particles comprises a material having a Vickers hardness greater than at least one of 20 GPa and 40 GPa. Wear resistant elements having a Vickers hardness of greater than 40 GPa are, in the context of this document, super hard materials.
In an embodiment, each of the plurality of round particles has an elastic modulus of greater than 200 GPa.
In an embodiment, the wear resistant element of each of the plurality of round particles has a coating metallurgically bonded thereto, the coating being metallurgically bondable to the wear resistant coating binder.
An embodiment comprises the step of the binding material penetrating the round outer layer of each of the plurality of round particles and forming a metallurgical bond with the coating. A third aspect of the invention provides a method for making a hardfacing powder for forming a wear resistant coating on a substrate. The method comprises the step of combining a plurality of round particles and a wear resistant coating binder. Each of the plurality of round particles comprises a round outer layer encapsulating a wear resistant element.
In an embodiment, for each of the plurality of round particles the round outer layer has a density greater than that of the wear resistant element.
In an embodiment, the wear resistant coating binder may comprise a plurality of metallic particles. The plurality of metallic particles may comprise a braze metal. The braze metal may comprise a braze alloy.
In an embodiment, the volume fraction of the plurality of round particles within the mixture is at least 0.05. The volume fraction of the plurality of round particles within the mixture may be no more than 0.85.
In an embodiment, the round outer layer comprises a composite. The composite may be a cermet. The cermet may be a polycrystalline cermet.
In an embodiment, the wear resistant element of each of the plurality of round particles has an ISO 6106 mesh size of at least 18. The wear resistant element of each of the plurality of round particles may have an ISO 6106 mesh size of no more than 80. The wear resistant element of each of the plurality of round particles may have an ISO 6106 mesh size of no more than 120. In an embodiment, the wear resistant element of each of the plurality of round particles comprises a material having a Vickers hardness greater than at least one of 20 GPa and 40 GPa.
In an embodiment, each of the plurality of round particles has an elastic modulus of greater than 200 GPa.
In an embodiment, the wear resistant element of each of the plurality of round particles has a coating metallurgically bonded thereto, the coating being metallurgically bondable to the wear resistant coating binder.
Disclosed herein is a wear resistant coating on a substrate. The wear resistant coating comprises a composite material comprising a plurality of round particles bound together by a wear resistant coating binder, each of the plurality of round particles comprising a round outer layer encapsulating a wear resistant element.
In an embodiment, the plurality of round particles have a close packed arrangement.
In an embodiment, the wear resistant coating comprises another plurality of particles that occupy a plurality of interstices between the plurality of round particles. The other plurality of particles may be round. The other plurality of particles may comprise a first plurality of particles having a first mean diameter and a second plurality of particles having a second mean diameter that is less than the first mean diameter. The second mean diameter may be less than 10% of the first mean diameter. The second plurality of particles may further increase the volume fraction of particles within the wear resistant coating when formed, which may improve the wear resistance of the wear resistant coating.
Disclosed herein is a wear resistant coating on a substrate, the wear resistant coating comprising:
a composite material comprising a plurality of round particles bound together by a wear resistant coating binder, wherein each of the plurality of round particles comprises a round outer layer encapsulating a wear resistant element, the wear resistant coating binder penetrates the round outer layer and is metallurgically bonded to a coating metallurgically bonded to the wear resistant element of each of the plurality of particles, wherein the wear resistant coating binder is metallurgically bonded to at least one of an inner surface and an outer surface of the round outer layer of each of the plurality of round particles.
Any of the various features of each of the above disclosures, and of the various features of the embodiments described below, can be combined as suitable and desired.
Embodiments will now be described by way of example only with reference to the accompanying figures in which:
A wear resistance coating may be formed on a substrate using other embodiments of the method of
The nozzle 76 is generally but not necessarily fluid cooled by a fluid in the form of water (or alternatively air or any generally suitable liquid) flowing through liquid chambers 80 formed in the nozzle 76.
The plasma stream heats the wear resistant coating binder and the plurality of round particles to a temperature greater than at least one of a wear resistant coating binder softening temperature and a wear resistant coating binder melting temperature. The wear resistant coating binder cools and hardens to bind the plurality of round particles.
Before application of the hardfacing powder 71 by one of the PTA surfacing processes described above, the surface 74 of the substrate 72 may be optionally cleaned by application of a grinder. Alternatively, a chemical cleaning agent, or generally any suitable cleaning process may be used. The substrate 72 may be steel or generally any substrate for which the method 12 is suitable. The surface may be preheated to 90-650 degrees centigrade prior to the PTA surfacing process by a resistive or inductive heater. Carbon and/or air quenched steels, for example, may be slow cooled after the PTA surfacing process.
In another embodiment, the plurality of round particles and wear resistant coating binder may be fed separately into the plasma stream directed at the substrate. For example, the wear resistant coating binder may be introduced into port 84 and the plurality of round particles into port 99.
Generally any suitable process may be used to form the coating, for example high velocity oxy-fuel deposition (HVOF). An example of a HVOF torch (otherwise known as a HVOF gun) 210 is shown in
The substrate may generally be any suitable substrate, examples of which include, but are not limited to a drill bit used by the mining or another industry, other down-hole equipment, the teeth of a bucket for an excavator, a chisel, and a blade.
For the hardfacing powder 10 of
In this embodiment, the round outer layer is a composite in the form of a cermet, with a theoretical density generally in the range of 15-19 g·cm−3. The cermet comprises comprise cobalt. Cobalt has a density of around 8.9 g·cm−3. The wear resistant element is a diamond, which has a density of around 3.5 g·cm−3.
The plurality of metallic particles may, for example, comprise any suitable brazing metal, example of which include copper, tin, silver, cobalt, nickel, cadmium, manganese, zinc or an alloy thereof. The metallic particles may also comprise chromium that hardens the alloy formed on solidification of the molten hardfacing powder. The wear resistant coating binder may also contain silicon and/or boron powder to aid in fluxing and deposition characteristics. In the present embodiment, the plurality of metallic particles comprise nickel, chromium, boron and silicon. Nickel may constitute 88%-95% by weight, chromium may constitute 0%-12%, boron may constitute 0%-1% and silicon may constitute 0%-1%.
In this but not necessarily in all embodiments, the round outer layer 28 comprises a polycrystalline cermet in the form of tungsten carbide particles sintered with cobalt particles. A cermet is generally a composite material composed of ceramic particles (for example an oxide, boride or carbide) bound together with a metallic material (examples of which include nickel, molybdenum and cobalt). The encapsulant 28 differs from the wear resistant element 26 in that, in this but not necessarily in all embodiments, it is of a lower hardness. The encapsulant is, in this but not necessarily in all embodiments, polycrystalline and prior to its fabrication into the hardfacing powder may be present in different forms such as having unreacted and un-bonded adjacent grains through to fully sintered with low-to-no measurable porosity. Alternatively, the round outer layer 28 may comprise a metal matrix composite, for example polycrystalline tungsten or molybdenum in a metal binder such as cobalt, nickel or iron.
The element 26 is, in this but not in all embodiments, metallurgically bonded to a coating intermediate of the element 26 and the encapsulating material 28. The coating may be deposited using different techniques, including but not limited to chemical vapor deposition, physical vapor deposition and metallization. Such techniques provide a coating that is generally of the order of one to a few microns thick; e.g. 1-2 microns. Examples of coating materials include but are not limited to titanium and silicon where the element 26 is a diamond.
The other plurality of particles may be constructed from different materials such as diamond, tungsten carbide, tungsten, alumina, silicon carbide and silicon nitride or generally any suitable material. Their size and distribution may be selected to maximize the packing density and wear behavior when deposited within the hard facing consumable. In this embodiment, they are tungsten carbide.
In the
In this but not necessarily in all embodiments, the volume fraction of the plurality of round particles is at least 0.05 and no more than 0.85. The wear resistant element of each of the plurality of round particles has, in this embodiment, an ISO 6106 mesh size of at least 18 and no more than 120. In an alternative embodiment, the wear resistant elements of each of the plurality of round particles may have an ISO 6106 mesh size of no more than 80. ISO stands for the International Standards Organization, and documents describing standard 6106 are publically available.
In an embodiment of a method for making the hardfacing powder 10, the plurality of round particles and the wear resistant coating binder are combined. This may comprise, for example, disposing the plurality of round particles and the wear resistant coating binder in a mixer or blender, for example an industrial blade mixer, turbola or a blender that executes a cone blending process.
The wear resistant coating binder may take the form of, for example, a powder comprising at least one of nickel, cobalt, tungsten carbide, chromium, and a fluxing agent. Fluxing agents may be self fluxing and/or chemical fluxing agents. Examples of self fluxing agents including silicon and boron, while chemical fluxing materials may be based on borates. In this embodiment, however, a fluxing agent and deoxidizer in the form of silicomanganese 2% Carbon (ELKEM CHEMICALS or CHEMALLOY) is added to the mixture. To form the mixture, the plurality of round particles, the wear resistant coating binder, the fugitive binder, and other particles as used including the other plurality of particles, may be mixed in an industrial blade mixer, tumbled in a tumble mixer, or generally mixed using any suitable mixing method.
The round outer layer of each of the plurality of round particles generally may comprise a porous or skeletal structure, in which internal surfaces define internal voids and/or passageways. The binding material penetrates the porous or skeletal structure, and may fill the internal voids and/or passageways, to form a web within the round outer layer of at least a majority of the plurality of round particles. This results in a strong mechanical attachment to the plurality of round particles. The binding material penetrates to the coating 30 intermediate of the elements 26 and the encapsulating material 28.
In the wear resistant coating when formed, the binding material may, as in the present embodiment, penetrate to the coating 30 intermediate of the elements 26 and the encapsulating material. The binding material is metallurgically bonded with the coating 30 intermediate of the element 26 and encapsulating material 28. Consequently, the wear resistant elements, in this embodiment diamonds, are metallurgically bonded to the wear resistant binder by way of the intermediate coating 30. This may generally improve the attachment of the wear resistant elements, especially when they are exposed by wear and mere mechanical attachment may be insufficient for their retention in the wear resistant coating. This may improve the wear resistant coating's performance and life.
The solidified wear resistant coating binder is, in this but not necessarily in all embodiments, also metallurgically bonded to the plurality of round particles (which may comprise metal), at the outer surfaces of the plurality of round particles, and at internal surfaces of the plurality of round particles. This may further increase the strength of the final wear resistant coating.
The metallurgical bonds disclosed herein may comprise diffused atoms and/or atomic interactions. Under such conditions, the component parts may be “wetted” to and by the binding material.
Fabrication of the Plurality of Round ParticlesAn example method for the fabrication of examples of the plurality of round particles will now be described. Generally, any suitable method for fabricating the plurality of round particles may be used. A mixture of tungsten carbide powder having a Fisher sub sieve size of 1 μm and cobalt powder having a Fisher sub sieve size of 1.2 μm were mixed 50/50 by weight. Alternatively or additionally to cobalt, any suitable metal powder, for example a powder comprising at least one of Nickel, copper, and alloys thereof. MBS955 Si2 40/50 mesh diamonds are tumbled in the mixture of tungsten carbide powder and cobalt powder with a binding agent in the form of methyl cellulose while controlled amounts of water is simultaneously sprayed thereon. Each diamond is coated to form the plurality of round particles in a green state. The plurality of round particles in the green state may then be heated in a Borel furnace under a protective hydrogen atmosphere. The plurality of round particles in the green state may be heated around room temperature to 500° C. over an hour approximately. The plurality of round particles are maintained at 500° C. for around 30 min. The temperature is then elevated to 850° C. over around 180 min. The sintered plurality of round particles are allowed to cool.
ApplicationsThe hardfacing powder 10 may be used to form a wear resistant coating on any suitable substrate. Some suggested applications are now described, however it will be appreciated that there are many applications of the wear resistant coating.
Stabilizers are used in the exploration and production of oil and gas. Their function is to provide stability to the drill bit and maintain dimensional control of the hole. Large sections of the stabilizer are in direct contact with the walls of the hole or steel casing. Through rotation of the drill string and progressive drilling, protective elements and hard facings are prone to wear which may eventually result in repair, end-of-life or dimensionally unacceptable diameters. Stabilizes having a wear resistant coatings described herein applied thereto may reduce or eliminate these issues.
Rotary bi- and tri-cone drill bits are manufactured with protrusions or “teeth” that are machined from parent steel. A drill bit having a wear resistant coating described herein applied thereto may have increased life and exhibit reduced “teeth” wear, which may increase drilling performance and productivity.
During mechanical excavation and removal of rock, significant wear can be seen on excavator teeth and buckets. Excavator teeth and buckets having a wear resistant coating described herein applied thereto may have prolonged life and consequently replacement costs may be reduced.
The outside diameter of a polycrystalline diamond drill bit is subject to sliding wear. A polycrystalline drill bit having a wear resistant coating described herein applied thereto may have an increased serviceable life.
During the life of a polycrystalline diamond drill bit the body and blades of the bit that support the cutting structure may be subject to life-limiting wear. Bodies and blades having a wear resistant coating described herein applied thereto may reduce erosive wear, which may increasing tool life and reduce costs.
Picks are used during the mechanical excavation of rock and the surface dressing of road surfaces. A pick is manufactured generally in two-pieces; body and insert. The body is conventionally steel and the insert commonly cemented carbide. In some circumstances diamond containing inserts are used. Body life is generally limited by excessive wear or “Wash”. A body having a wear resistant coating as described herein and in close proximity to the insert may have prolonged life, and reduce down time required for replacing worn picks.
Crusher teeth may be used in various applications including in the mechanical extraction of oil from oil containing sand. The crusher teeth may be positioned around a rotating drum and mechanically interact with the rock, sand and oil. Wear may be great. Crusher teeth having a wear resistant coating as described herein applied thereto may have prolonged life.
In the context of gas and oil drilling, a mud-powered motor drives bit rotation and torque. The motor may contain both radial and axial bearings that are in sliding contact with opposing bearings or rolling elements. A bearing having a wear resistant coating as described herein applied thereto may significantly increase bearing life, reduce bearing length and offer the ability for more sets of bearings that promote higher bit-weights and better productivity when drilling for oil and gas.
Now that embodiments have been described, it will be appreciated that some embodiments may have some of the following advantages:
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- Wear resistant elements may have a relatively low density. Consequently, in the prior art, the wear resistant elements may be poorly distributed in the wear resistant coating and may be in close proximity to one another, or even touching which may weaken the structure because infiltration may be reduced. Thin coatings onto a super hard material may not fully overcome these density differences or avoid part-to-part contact. Encapsulation of the wear resistant elements and penetration of the round outer layer by the binding material) may ameliorate these problems.
- The round nature of the encapsulant and/or careful selection of sizes and shapes of interstices occupying particles promotes high packing and further optimizes wear resistance.
- The structure of the encapsulant may be either an open or closed structure. An open semi-porous topography may provide high surface area and strong capillary forces for reaction and infiltration.
- During cooling and solidification of the molten wear resistant coating binder, the encapsulated wear resistant elements may be placed under compression by the encapsulant, providing improved retention and better wear properties.
- The liquid metal infiltration of the encapsulant during the coating process and subsequent solidification may provide a mechanically improved compressive stress that holds and bonds the wear resistant elements in. This advantage may not be enjoyed by non-encapsulated super hard elements.
- The wear resistant elements may be metallurgically bonded to the wear resistant binder by way of the intermediate coating 30. This may improve the attachment of the wear resistant elements and the wear resistant coating's performance and life.
The wear resistant elements discussed herein may have significantly increased hardness and wear resistance compared to tungsten carbide based metal matrices formed by conventional hardfacing materials. Variations and/or modifications may be made to the embodiments described without departing from the spirit or ambit of the invention. For example, while the substrate disclosed above is steel, it will be appreciated that embodiments may be used on other substrate materials, for example another metal such as aluminum, a cemented carbide, or generally any suitable substrate material. The powder may be poured or otherwise applied onto the substrate. The powder may be fused by heating the substrate and powder thereon in a furnace. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.
Prior art, if any, described herein is not to be taken as an admission that the prior art forms part of the common general knowledge in any jurisdiction.
In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, that is to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
Claims
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/cm3; 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.
Type: Application
Filed: Mar 25, 2019
Publication Date: Jul 18, 2019
Inventor: Andrew BELL (Forthampton)
Application Number: 16/363,631