FIELD OF THE INVENTION
The present invention is directed to coated grinding articles and methods for forming coated grinding articles. More particularly, the present invention is directed to coated grinding articles and methods for forming coated grinding articles having a plurality of particles dispersed in a matrix in the coating.
BACKGROUND OF THE INVENTION
Coal crusher rolls are used to crush coal which is fed to a boiler for producing steam, reducing the size of the coal units from about 20 mm to about 200 mesh size. During the crushing process, the grinding surfaces of the coal crusher rolls become worn due to the inherent abrasive nature of the coal which is being crushed. Coals which have elevated ash content are typically more abrasive than coals with lower ash content, and may cause faster erosion of the grinding surfaces of the coal crusher roles, both by attrition and wear from the crushing loads applied on the coal crusher rolls. Further degradation of the coal crusher rolls may be caused by contaminants in the coal supply such as iron and stone, which may cause sudden impacts when introduced into the coal crusher.
Coal crusher rolls may be encased in sinter-cast materials to extend the useful life, but such solutions are expensive and are limited in the increase in useful life they provide.
BRIEF DESCRIPTION OF THE INVENTION
In an exemplary embodiment, a coated grinding article includes a support portion and at least one coating disposed on the support portion. The support portion includes a support portion hardness, and the at least one coating includes a matrix having a matrix hardness, a plurality of particles having a particle hardness dispersed in the matrix, and a grinding surface. The particle hardness is greater than the matrix hardness and is greater than the support portion hardness.

In another exemplary embodiment, a method for forming a coated grinding article includes applying at least one coating to a support portion. The support portion includes a support portion hardness. Applying the at least one coating includes forming a matrix having a matrix hardness on the support portion and dispersing a plurality of particles having a particle hardness in the matrix. The particle hardness is greater than the matrix hardness and is greater than the support portion hardness. Applying the at least one coating to the support portion forms a grinding surface of the coated grinding article.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an assembly, according to an embodiment of the present disclosure.
FIG. 2 is a sectional view along lines 2-2 of a grinding article of the assembly of FIG. 1, according to an embodiment of the present disclosure.
FIG. 3 is an expanded sectional view of area 3 of the grinding article of FIG. 2, according to an embodiment of the present disclosure.
FIGS. 4A-L are perspective views of grinding surfaces of FIG. 2 having predetermined patterns of particle distributions (hexagonal - FIGS. 4A and 4G; pentagonal - FIGS. 4B and 4H; quadrilateral - FIGS. 4C and 41; triangular -FIGS. 4 D and 4 J; striped - FIGS. 4E and 4K; and zig-zag - FIGS. 4F and 4L) before (FIGS. 4A-F) and after (FIGS. 4G-L) exposure to operational conditions, according to embodiments of the present disclosure.
Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.

DETAILED DESCRIPTION OF THE INVENTION
Provided are exemplary grinding articles, and methods for forming the grinding articles. Embodiments of the present disclosure, in comparison to articles and methods not utilizing one or more features disclosed herein, decrease costs, increase process efficiency, increase durability, increase reliability, increase service lifetime, decrease erosion, decrease wear, or a combination thereof.
Referring to FIGS. 1-3, in one embodiment, a coated grinding article 100 includes a support portion 200 and at least one coating disposed 202 on the support portion 200. The support portion 200 includes a support portion hardness, and the at least one coating 202 includes a matrix 300 having a matrix hardness and a plurality of particles 302 having a particle hardness dispersed in the matrix 300. The support portion hardness is an average hardness of the support portion 200 determined at a support portion surface 204 proximal to the at least one coating 202. The matrix hardness may be less than the support hardness, about equal to the support hardness, or greater than the support portion hardness, and the particle hardness is greater than the matrix hardness and the support hardness. The at least one coating 202 further includes a grinding surface 206 distal across the at least one coating 202 from the support portion surface 204.
The grinding surface 206 may include any suitable grinding surface roughness. The grinding surface roughness may be less than the a support surface roughness of the support portion surface 204, the grinding surface roughness may be about the same as the support surface roughness, or the grinding surface roughness may be greater than the support surface roughness. In one embodiment, the grinding surface roughness is at least about 5% greater than the support surface roughness, alternatively at least about 10% greater than the support surface roughness, alternatively at least about 15% greater than the support surface roughness, alternatively at least about 25% greater than the support surface roughness, alternatively at least about 50% greater than the support surface roughness, alternatively at least about twice the support surface roughness, alternatively at

least about five times the support surface roughness, alternatively at least about ten times the support surface roughness.
The at least one coating 202 may be disposed directly on the support portion surface 204 or may be disposed on an intermediate layer (not shown) such as a bond coat. Any suitable bond coat may be disposed between the support portion surface 204 and the at least one coating 202, including, but not limited to, molybdenum, M-5A1, Ni-20A1, Ni-20Cr, MCrAlY (where M is nickel, cobalt, or iron), or combinations thereof.
The support portion 200 may include any suitable structural composition. In one embodiment, the support portion 200 includes a first layer 208 having a first layer hardness. In another embodiment, the support portion 200 further includes a second layer 210 having a second layer hardness. The second layer hardness may be greater than the first layer hardness or lesser than the first layer hardness. In yet another embodiment, the support portion 200 further includes a third layer 212 having a third layer hardness. The third layer hardness may be greater than the second layer hardness or lesser than the second layer hardness, and may be greater than the first layer hardness or lesser than the first layer hardness. The support portion 200 may further include any suitable number of additional layers. In one embodiment, the support portion 200 includes a first layer 208, a second layer 210, and a third layer 212, the second layer 210 being disposed between the first layer 208 and the at least one coating 202, and the third layer 212 being disposed between the second layer 210 and the at least one coating 202, wherein the second layer hardness is greater than the first layer hardness, the third layer hardness is greater than the second layer hardness, and the third layer hardness is less than, greater than, or about equal to the matrix hardness.
The first layer 208 may include any suitable material, including, but not limited to, cast iron, spheroidal graphite iron, white cast iron, cast iron including niobium, cast iron including chromium, cast iron including titanium, Hadfield steel (MANGALLOY®), cast steel, locomotive wheel steel, or combinations thereof.

The first layer 208 may include any suitable diameter, including, but not limited to, a first layer average diameter 214 of between about 10 mm and about 3 m, alternatively between about 25 mm and about 2.5 m, alternatively between about 50 mm and about 2 m.
The second layer 210 may include any suitable material, including, but not limited to, a chrome-iron alloy including, by weight, at least about 30% chrome, cast iron, spheroidal graphite iron, white cast iron, cast iron including niobium, cast iron including chromium, cast iron including titanium, Hadfield steel (MANGALLOY®), cast steel, locomotive wheel steel, or combinations thereof. The second layer 210 may include any suitable thickness, including, but not limited to, a second layer thickness 216 of between about 0.1 mm and about 50 mm, alternatively between about 0.5 mm and about 10 mm, alternatively between about 1 mm and about 5 mm.
The third layer 212 may include any suitable material, including, but not limited to, a weld hardface material. Suitable hardface materials may include, but are not limited to, materials including carbides as one of at least two constituents, cobalt-chromium alloys (such as the commercially available STELLITE® alloys, cobalt-molybdenum-chromium-silicon alloys (such as the commercially available TRTBALOY® family of alloys), and combinations thereof. The third layer 212 may include any suitable thickness, including, but not limited to, a third layer thickness 218 of between about 0.1 mm and about 10 mm, alternatively between about 0.25 mm and about 5 mm, alternatively between about 0.5 mm and about 3 mm.
The at least one coating 202 may include any suitable thickness, including, but not limited to, a coating thickness 220 of between about 0.1 mm and about 10 mm, alternatively between about 0.25 mm and about 5 mm, alternatively between about 0.5 mm and about 3 mm.
The coated grinding article 100 may be any suitable article. In one embodiment, the zgrinding article 100 is a grinding roll 102. The grinding roll 102 may be an

independent component or the grinding roll 102 may be a component of a grinding apparatus 104, such as, but not limited to, a bowl mill, a ball and race mill, a drum and ball mill, a coal crusher, or combinations thereof.
The plurality of particles 302 may include any suitable particles. In one embodiment, the plurality of particles 302 includes a plurality of ceramic particles. Suitable ceramic particles may include, but are not limited to, particles formed from a material including metal carbides, metal borides, metal oxides, boron nitrides, boron carbides, boron carbon nitrides, zirconia toughened aluminas, silicon carbides, silicon nitrides, silicon oxy-nitrides, silicon aluminum oxy-nitrides, or combinations thereof.
The plurality of particles 302 may include any suitable particle size distribution, including, but not limited to, a particle size distribution of up to about 10 nm, alternatively up to about 20 nm, alternatively up to about 25 nm, alternatively up to about 10 mm, alternatively up to about 20 mm, alternatively up to about 25 mm, alternatively from about 1 nm to about 25 mm, alternatively from about 1 nm to about 25 nm, alternatively from about 1 mm to about 25 mm.
The matrix 300 may include any suitable material, including, but not limited to, cobalt-chromium alloys, nickel-chromium alloys, nickel aluminum alloys, iron-chromium alloys, iron-chromium-aluminum alloys, nickel-aluminum-chromium alloys, or combinations thereof.
In one embodiment, the plurality of particles 302 in the coated grinding article 100 is essentially free of oxidation and decarburization chemical structure modifications. As used herein, "essentially free" indicates that less than about 20%, by weight, of the plurality of particles 302 are oxidized or decarburized, alternatively less than about 15%, by weight, alternatively less than about 10%, by weight, alternatively less than about 5%, by weight, alternatively less than about P/o, by weight, alternatively less than about 0.5%, by weight.
The plurality of particles 302 may be randomly dispersed in the matrix 300, multi-

modally dispersed in the matrix 300, essentially uniformly dispersed in the matrix 300, uniformly dispersed in the matrix 300, dispersed in the matrix 300 per a predetermined pattern, or combinations thereof. As used herein, "multi-modally dispersed" indicates a region having a greater concentration and a region having a lesser concentration, and "essentially uniformly dispersed" indicates a variance in concentration throughout the matrix 300 of less than about 20%, alternatively, less than about 15%, alternatively less than about 10%, alternatively less than about 5%>, alternatively less than about 1%. "Multi-modally dispersed" further may refer to the distribution of different sizes within the plurality of particles 302. Fine and coarse particles within the plurality of particles 302 may be distributed in the matrix 300 to optimize protection against erodent abrasive particles having different sizes. Fine particles in the plurality of particles 302 may also fill in gaps which may be present between coarse particles in the plurality of particles 302, thereby enhancing the resistance of the plurality of particle 302 to erosion and abrasion.
Referring to FIGS. 4A-L, in one embodiment, wherein the plurality of particles 302 is dispersed in the matrix 300 according to a predetermined pattern, a higher concentration of the plurality of particles 302 is disposed in a first region 400 of the grinding surface 206 relative to a second region 402 of the grinding surface 206. Under operating conditions, the predetermined pattern at the grinding surface 206 may result in a three-dimensional pattern formed by the differential abrasion of the plurality of particles 302 and the matrix 300, which may be designed to provide additional operational enhancements. The predetermined pattern may be any suitable pattern, including, but not limited to, a hexagonal "honey-comb" lattice (FIG. 4A), a pentagonal lattice (FIG. 4B), a quadrilateral lattice (FIG. 4C), a triangular lattice (FIG. 4D), a striped pattern (FIG. 4E), a zig-zag pattern (FIG. 4F), or combinations thereof, which may form, respectively, after operational wear, a honey-comb texture (FIG. 4G), a pentagonal texture (FIG. 4H) a cuboid texture (FIG. 41), a pyramidal texture (FIG. 4J), a ridged texture (FIG. 4K), a zig¬zag ridged texture (FIG. 4L), or combinations thereof. In another embodiment

(not shown), a higher concentration of the plurality of particles is disposed in regions of the at least one coating 202 where the coated grinding article 100 is subjected to greater wear during operation, such as, by way of example, the middle of the coated grinding article 100 relative to the edges of the coated grinding article 100.
In one embodiment, the plurality of particles 302 is dispersed in the matrix 300 at a density (average, by weight) of at least about 50%, alternatively at least about 55%, alternatively at least about 60%, alternatively at least about 65%, alternatively at least about 75%, alternatively at least about 80%, alternatively at least about 85%, alternatively at least about 90%, alternatively between about 50%) to about 99%), alternatively between about 60% to about 95%, alternatively between about 75% to about 94%, alternatively between about 85% to about 93%, alternatively between about 90% to about 95%, alternatively about 93%.
In one embodiment, a method for forming a coated grinding article 100 includes applying the at least one coating 202 to the support portion 200. Applying the at least one coating 202 includes forming the matrix 300 on the support portion 200 and dispersing the plurality of particles 302 in the matrix 300. Applying the at least one coating 202 to the support portion 200 forms the grinding surface 206 of the coated grinding article 100. Forming the matrix 300 on the support portion 200 and dispersing the plurality of particles 302 in the matrix 300 may include any suitable method, including, but not limited to thermally spraying the at least one coating 202. Thermally spraying the at least one coating 202 may include, but is not limited to, cored wire arc spraying, wire arc spraying, high velocity air fuel spraying, cold spraying, or combinations thereof. Applying the at least one coating 202 may be essentially free of oxidizing and decarburizing the plurality of particles 302.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from

the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

WE CLAIM:
1. A coated grinding article, comprising:
a support portion including a support portion hardness; and at least one coating disposed on the support portion, the at least one coating including:
a matrix having a matrix hardness; and a plurality of particles having a particle hardness dispersed in the matrix, the particle hardness being greater than the matrix hardness and greater than the support portion hardness, wherein the at least one coating further includes a grinding surface.
2. The coated grinding article as claimed in claim 1, wherein the support
portion includes
a first layer having a first layer hardness;
a second layer having a second layer hardness greater than the first layer hardness; and
a third layer having a third layer hardness greater than the second layer hardness,
wherein the second layer is disposed between the first layer and the at least one coating, and the third layer is disposed between the second layer and the at least one coating.
3. The coated grinding article as claimed in claim 2, wherein the first layer includes a material selected from the group consisting of cast iron, spheroidal graphite iron, white cast iron, cast iron including niobium, cast iron including chromium, cast iron including titanium, Hadfield steel, cast steel, locomotive wheel steel, and combinations thereof.
4. The coated grinding article as claimed in claim 2, wherein the second layer includes a material selected from the group consisting of chrome-iron alloy including, by weight, at least about 30% chrome, cast iron,

spheroidal graphite iron, white cast iron, cast iron including niobium, cast iron including chromium, cast iron including titanium, Hadfield steel, cast steel, locomotive wheel steel, and combinations thereof.
The coated grinding article as claimed in claim 2, wherein the third layer includes a weld hardface material.
The coated grinding article as claimed in claim 1, wherein the at least one coating includes a coating thickness of between about 0.1 mm to about 10 mm.
The coated grinding article as claimed in claim 1, wherein the coated grinding article is a grinding roll of an apparatus selected from the group consisting of a bowl mill, a ball and race mill, a drum and ball mill, a coal crusher, and combinations thereof
The coated grinding article as claimed in claim 1, wherein the plurality of particles includes a plurality of ceramic particles, the plurality of ceramic particles being selected from the group consisting of metal carbides, metal borides, metal oxides, boron nitrides, boron carbides, boron carbon nitrides, zirconia toughened aluminas, silicon carbides, silicon nitrides, silicon oxy-nitrides, silicon aluminum oxy-nitrides, and combinations thereof.
The coated grinding article as claimed in claim 1, wherein the matrix includes a material selected from the group consisting of cobalt-chromium alloys, nickel-chromium alloys, nickel aluminum alloys, iron-chromium alloys, iron-chromium-aluminum alloys, nickel-aluminum-chromium alloys, and combinations thereof.
The coated grinding article as claimed in claim 1, wherein the plurality of particles includes a particle size distribution of between about 1 nm to about 25 nm, or between about 1mm to about 25 mm.
The coated grinding article as claimed in claim 1, wherein the plurality of particles is essentially uniformly dispersed in the matrix.

The coated grinding article as claimed in claim 1, wherein the plurality of particles is dispersed in the matrix at an average density by weight, of at least about 50%.
The coated grinding article as claimed in claim 1, wherein the plurality of particles is essentially free of oxidation and decarburization chemical structure modifications.
The coated grinding article as claimed in claim 1, wherein the matrix hardness is at least equal to the support portion hardness.
The coated grinding article as claimed in claim 1, wherein the grinding surface includes the predetermined pattern of the plurality of particles having a higher concentration of the plurality of particles disposed in a first region of the grinding surface relative to a second region of the grinding surface, and the predetermined pattern is selected from the group consisting of a hexagonal "honey-comb" lattice, a pentagonal lattice, a quadrilateral lattice, a triangular lattice, a striped pattern, a zig-zag pattern, and combinations thereof.
A method for forming a coated grinding article, comprising:
applying at least one coating to a support portion including a support portion hardness, applying the at least one coating including: forming a matrix having a matrix hardness on the support portion; and
dispersing a plurality of particles having a particle hardness in the matrix, the particle hardness being greater than the matrix hardness and greater than the support portion hardness, wherein applying the at least one coating to the support portion forms a grinding surface of the coated grinding article.
The method as claimed in claim 16, wherein applying the at least one coating to the support portion includes forming the matrix including a

material selected from the group consisting of cobalt-chromium alloys, nickel-chromium alloys, nickel aluminum alloys, iron-chromium alloys, iron-chromium-aluminum alloys, nickel-aluminum-chromium alloys, and combinations thereof, and dispersing the plurality of particles in the matrix includes dispersing a plurality of ceramic particles selected from the group consisting of metal carbides, metal borides, metal oxides, boron nitrides, boron carbides, boron carbon nitrides, zirconia toughened aluminas, silicon carbides, silicon nitrides, silicon oxy-nitrides, silicon aluminum oxy-nitrides, and combinations thereof.
The method as claimed in claim 16, wherein forming the matrix on the support portion and dispersing the plurality of particles in the matrix includes thermally spraying the at least one coating.
The method as claimed in claim 18, wherein thermally spraying the at least one coating includes a technique selected from the group consisting of cored wire arc spraying, wire arc spraying, high velocity air fuel spraying, cold spraying, and combinations thereof.
The method as claimed in claim 16, wherein applying the at least one coating is essentially free of oxidizing and decarburizing the plurality of particles.