Description:TECHNICAL FIELD
[001] This disclosure relates generally to the field of surface treatments, more specifically, this disclosure relates to coating a high emissivity material to a surface of an alloy.
BACKGROUND
[002] Many automotive components in automobiles use gray cast iron as a primary material. One of such components may include braking systems, such as disc braking system or drum braking system. As commonly known in the art, disc braking system may include a disc and a pad configured to engage with the disc, to effect braking of the automobile. Another common example of the braking system may include a drum braking system. Drum braking system employs a drum and a shoe, and the shoe configured to engage with the drum to cease motion of the automobile. The disc, and the drum use gray cast iron as their primary material of manufacture.
[003] The braking action may be realized by engaging the pad with the disc or the shoe with the drum may restrict the motion of the disc or the drum, due to friction occurring between the pad and the disc, and between the shoe and the drum. The kinetic energy of the rotating disc or drum may be converted and emitted as thermal energy, which may be dissipated as heat. Further, this heat may spread from the disc or the drum onto other components of the braking system. Conventionally, heat produced during braking systems are dissipated to the environment using air cooling systems, or by using active cooling systems. Air cooling of the disc or the drum may use a radial vent, such as fins, and accommodated between the surfaces of the disc or the drum. But the air-cooling system may not be efficient in complete dissipation of heat from the disc, or the drum, and hence still may result in accumulation and spreading of heat to other components of the braking system. Accumulation of heat in the braking system may result in wearing of the pads, or the shoe, degradation of the pad resin or shoe resin, cracking of brake liner, fading of brake, cracking of disc or the drum, brake noise, and the like. Further, active cooling systems may include using coolant fluid to absorb heat produced by the braking application. But provision of active cooling to the braking systems may involve increase in complexity of assembly, given the limited space between the braking system and the wheel.
[004] Therefore, there is a need for braking system to effectively dissipate heat to atmosphere.

SUMMARY
[005] In one embodiment, a method adhesion of high emissivity material to a surface is disclosed. In a first step, a metal layer from at least one portion of an object may be selectively removed using at least one surface treatment technique to expose a plurality of graphite flakes. The object may be made of metal-graphite alloy. In the next step, a high emissivity material may be coated over the at least one portion of the object for adhesion to the at least one portion, after removing the metal layer thereof. The high emissivity material may be configured to submerge and anchor the exposed plurality of graphite flakes.
[006] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[007] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles.
[008] FIG. 1 illustrates a schematic layout of a method of coating a surface of a metal-graphite alloy with a high emissivity material, as an embodiment of the present disclosure;
[009] FIG. 2 illustrates a perspective view of an object coated with the high emissivity material, using the method of FIG.1, as an embodiment of the present disclosure;
[010] FIG. 3 illustrates a perspective view of another object coated with the high emissivity material, using the method of FIG.1, as an embodiment of the present disclosure;
[011] FIG. 4 illustrates a flow chart of a method of masking the surface of the metal-graphite alloy, as an embodiment of the present disclosure; and
[012] FIG. 5 illustrates a flow chart of a method of coating the surface of the metal-graphite alloy with a high-emissivity material, as an embodiment of the present disclosure.
DETAILED DESCRIPTION
[013] The foregoing description has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which forms the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying other devices, systems, assemblies and mechanisms for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that, such equivalent constructions do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristics of the disclosure, to its device or system, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
[014] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusions, such that a system or a device that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
[015] Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible, same numerals have been used to refer to the same or like parts. The following paragraphs describe the present disclosure with reference to FIGs. 1-5.
[016] Metal-graphite alloys may include metal with a small content of carbon. Classic example of metal-graphite alloy may include cast iron, in which iron may include a carbon content of more than 2%. Cast iron may be further categorized into gray cast iron, white cast iron, ductile cast iron, and malleable cast iron. Preferably, for applications in automobile technology, gray cast iron may be selected, due to high compressive strength, high thermal conductivity, corrosion resistance, and superior machineability. However, due to high thermal conductivity, the heat generated during various applications, such as for example, braking action, high heat may be generated, and may be further conducted to other components of the assembly, and may cause wear, or cracking of the other components. Therefore, to prevent such phenomenon, heat must be dissipated to atmosphere, at a rate faster than thermal conductivity.
[017] To this end, a method of coating a high-emissivity material on the surface of a metal-alloy graphite is disclosed. The method may include removal of a metal layer from the at least one portion of the surface of the metal-alloy graphite, to expose a plurality of graphite flakes therefrom. After the removal, the at least one portion may be coated with a high emissivity metallic or non-metallic material. The coated surface may exhibit high rate of heat dissipation to the atmosphere, without using any active cooling system.
[018] In one embodiment, referring now to FIG. 1, a schematic layout 100 of a method of coating a surface of a metal-graphite alloy is disclosed. The method, as depicted by the schematic layout 100, may involve a three-step procedure to adhere a high emissivity material on a surface of the metal-graphite alloy.
[019] In another embodiment, at step 1, a metal-graphite alloy, such as cast iron, and preferably gray cast iron may be selected as a substrate. As seen in FIG.1, a microstructure 102 of the substrate may include a plurality of graphite flakes 104. Initially, the graphite flakes 104 may be completely engraved within the microstructure 102 of the substrate, i.e., the graphite flakes 104 may not be protruding from the surface of the substrate. In the same step, a portion 106 of the microstructure 102 may be selected, i.e., a portion 106 which may be subjected to high heat may be selected. The remaining portion of the microstructure 102 may be masked accordingly. In another embodiment, a surface of the portion 106 of the microstructure 102 may be exposed to the coating process, which may be illustrated in detail hereon.
[020] In another embodiment, at step 2, the surface of the portion 106 may be subjected to a chemical surface treatment process. The chemical surface treatment process may include exposing the surface of the portion 106 to a chemical solution for a predefined time, and at a predefined temperature. After the chemical surface treatment process, the portion 106 may be processed to form a processed surface 108. As explained earlier, the substrate being gray cast iron, the selected surface of the microstructure 102 may be eroded to selectively remove the layer of iron. In this embodiment, process of forming the processed surface 108 may result in exposure of graphite flakes 104 from the microstructure 102. The graphite flakes 104 may be partially exposed, i.e., a portion of the graphite flakes 104 may still be rooted in the microstructure 102, and the remaining portion of the graphite flakes 104 may project from the processed surface 108.
[021] In another embodiment, the chemical solution to which the surface of the portion 106 may be treated, may include combination of at least one of hydrochloric acid (HCl), 2 to 4 M aqueous solution of iron chloride (FeCl3)—, sodium chloride (NaCl), potassium chloride (KCl), hydrogen fluoride (HF), phosphoric acid (H3PO4), nitric acid (HNO3). Other examples of such combination may also include 95–99 ml ethanol and 1–5 ml nitric acid, or 4% picric acid ((O2N)3C6H2OH) in ethanol to form a picric acid alcoholic solution of ethanol, or 1 g picric acid, and 5 mL HCl in 100mL ethanol . In another embodiment, the surface of the portion 106 may be subjected to the chemical solution for a predefined time period ranging between 5-25 minutes, and at a temperature ranging between ranging between 25 ? to 80 ?. In the same embodiment, a predefined thickness of iron ranging between 10-30 microns from the surface of the portion 106 may be selectively removed.
[022] In another embodiment, at step 3, the processed surface 108 may be subjected to a coating process, i.e., a layer of a high-emissivity material 110 may be coated on the processed surface 108. This step may initially involve selection of the high-emissivity material 110 from a metal, or a non-metal, which may be configured to exhibit high heat emissivity, i.e., emissivity ranging between 0.80e-1e. Examples of such materials may include any one of graphite or graphene, in combination with any one of boron nitride, aluminium nanoparticles, or copper nanoparticles. The high-emissivity material 110 may be coated on the processed surface 108 using any coating method(s) known in the art of manufacturing processes.
[023] In another embodiment, the high-emissivity material 110 may be configured to bond with the partially exposed graphite flakes 104. By bonding, the graphite flakes 104 may be submerged in the layer of high-emissivity material 110, such that the graphite flakes 104 may anchor the layer of high-emissivity material 110. Further, after coating the processed surface 108 with the high-emissivity material 110, the resulting microstructure 102 may be subjected to a liquid bath, as a finishing process. The liquid bath may include a warm water solution. Optionally, instead of warm water solution, the resulting microstructure 102 may also be subjected to hot air. The finishing process may be configured to complete or improve the adhesion, or the bonding between the graphite flakes 104 and the high-emissivity material 110.
[024] In one embodiment, now referring to FIG.2, which illustrates a perspective view 200 of an object. The object may include a drum brake 202, which may be manufactured, with gray cast iron as a primary material. Further, the drum brake 202 may include an inner surface 204, and an outer surface 206. The inner surface 204 may be configured to engage with a brake shoe 302 (refer to FIG.3). Further, during braking application, the engagement of the brake shoe 302 with the inner surface 204 may result in generation of heat. This generated head may be transmitted from the inner surface 204 to the outer surface 206, and may be dissipated to the atmosphere. Since the inner surface 204 may be subjected to high heat, therefore, it may be necessary for the outer surface 206 to exhibit high emissivity of heat, to effectively dissipate heat received from inner surface 204. Therefore, to increase heat emissivity, the outer surface 206 may be subjected to the method explained in conjunction with FIG.1.
[025] Similarly, in another embodiment, again referring to FIG.3, a perspective view 300 of another object is illustrated. The another object may include a brake shoe 302. The brake shoe 302 may include a brake liner 306. The brake liner 306 may be connected to a metal backplate 308 having an inner surface 304. In another embodiment, and as explained earlier, the brake shoe 302 may be configured to engage inner surface 204. Particularly, the brake liner 306 of the brake shoe 302 may be configured to engage the inner surface 204 of the drum brake 202 during the braking application. As a result, heat may also be generated in the brake liner 306, which may be transmitted to the inner surface 304 of the metal backplate 308. Therefore, it may be necessary for the inner surface 304 to exhibit high emissivity of heat received from brake liner 306. Therefore, to increase heat emissivity, the inner surface 304 may be subjected to the method explained in conjunction with FIG.1. After coating the inner surface 204 and the inner surface 304, the coated surfaces may exhibit an emissivity of 0.99e in an infrared wavelength band ranging between 0.5-13.5µm.
[026] As explained earlier, the portion in the microstructure 102 which may be subjected to high heat may be selected for coating, and the remaining portion of the microstructure may be masked accordingly, to prevent excess removal of the metal. Now, referring to FIG.4, which illustrates a flowchart 400 of a method of masking the surface of the metal-graphite alloy, as an embodiment of the present disclosure. As explained earlier, the metal-graphite alloy may include gray cast iron. At step 402, at least one portion 106 of the object may be exposed. The portion 106 may be identified as the portion of the microstructure 102 subjected to high heat. Further, at step 404, the remaining portion of the microstructure 102 may be masked accordingly, to prevent excess removal of the metal. Further, at step 406, the metal layer from the portion 106 may be selectively removed to expose a plurality of graphite flakes, using at least one surface technique, which is explained in detail with conjunction to FIG.1.
[027] Now, referring to FIG.5, a flow chart 500 of a method of coating the surface of the metal-graphite alloy with a high-emissivity material is illustrated, as an embodiment. At step 502, a metal layer from at least one portion of an object may be selectively removed using at least one surface treatment technique to expose a plurality of graphite flakes 104. The object may be made of metal-graphite alloy, such as gray cast iron. At step 504, a high emissivity material may be coated over the at least one portion of the object for adhesion to the at least one portion, after removing the metal layer thereof. The high emissivity material may be configured to submerge and anchor the exposed plurality of graphite flakes thereto. At step 506, the object in a warm water solution may be immersed and heated, to complete adhesion of the high emissivity material to the at least one portion. This is explained in detail in conjunction with FIG.1.
[028] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
[029] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[030] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.
[031] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
, Claims:CLAIMS

I/We claim:

1. A method (500) of adhesion of high emissivity material to a surface, the method (500) comprising:
selectively removing (406, 502), using at least one surface treatment technique, a metal layer from at least one portion (106) of an object (202, 302) to expose a plurality of graphite flakes (104), wherein the object (202, 302) is made up of a metal-graphite alloy: and
coating a high emissivity material (110) for adhesion over the at least one portion (106) after removing the metal layer, wherein coating of the high emissivity material (110) submerges and anchors the exposed plurality of graphite flakes (104) into the high emissivity material (110).

2. The method (500) as claimed in claim 1, comprising heating the object (202, 302) in a warm water solution to complete adhesion of the high emissivity material (110) to the at least one portion (106).

3. The method (500) as claimed in claim 1, wherein thickness of the metal layer is selected from a range varying between 10 microns to 30 microns.

4. The method (500) as claimed in claim 1, wherein the high emissivity material (110) is spray coated over the at least one portion (106).

5. The method (500) as claimed in claim 1, wherein the surface treatment technique comprises exposing the surface of the at least one portion to a solution comprising at least one of hydrochloric acid, iron chloride, sodium chloride, potassium chloride, hydrogen fluoride, phosphoric acid, nitric acid, or picric acid.

6. The method (500) as claimed in claim 5, wherein selectively removing the metal layer from the at least one portion (106) comprises exposing the at least one portion (106) to the solution for a time period selected from a range varying from 5 minutes to 25 minutes.

7. The method (500) as claimed in claim 5, wherein selectively removing the metal layer from the at least one portion (106) comprises exposing the at least one portions to the solution at temperature ranging between 25 ? to 80 ?.

8. The method (500) as claimed in claim 1, wherein the high emissivity materials (110) comprise at least one of graphene, boron nitride, aluminium nanoparticles, or copper nanoparticles.

9. The method (500) as claimed in claim 1, comprising:
exposing (402) the at least one portion (106) of the object (202, 302) for the at least one surface treatment technique; and
masking (404) the remaining at least one portion of the object (202, 302) to prevent removal of metal layer.

10. The method (500) as claimed in claim 1, wherein the metal-graphite alloy is cast iron and the removed metal layer is iron.

11. The method as claimed in claim 1, wherein the object (202, 302) is one of a disc brake or a drum brake (202).