WO2008101222A1

WO2008101222A1 - Low cost coating of substrates

Info

Publication number: WO2008101222A1
Application number: PCT/US2008/054177
Authority: WO
Inventors: John Hamiltion Madok
Original assignee: Scoperta Inc.
Priority date: 2007-02-16
Filing date: 2008-02-15
Publication date: 2008-08-21

Abstract

A substrate coating technology for coating a substrate with a coating material having a substantially similar base composition as the material composing the substrate is disclosed. The chemical composition of the coating material is selected to have a melting temperature lower than the melting temperature of the substrate such that the coating material exhibits deep eutectic properties when compared to the substrate. The chemical composition allows the molten coating material to be applied to the substrate by dipping the substrate or pouring onto the substrate.

Description

LOW COST COATING OF SUBSTRATES

Field of the Invention

[0001] The present invention relates to coating substrates with a protective coating, and more particularly to a method of coating a substrate with a coating material having a substantially similar base composition as the substrate to be coated.

Background of the Invention

[0002] Prior methods of coating substrates are generally either a batch process or a "sequential single" process. In a batch process, a group of substrates are processed together, and each step in the substrate deposition process is done on the group as a whole. In a "sequential single" process, a single substrate or even a part of a substrate is processed. For example, a spray gun may be used to coat one section of a substrate at a time such as spraying coating onto a substrate as the substrate is moved underneath the spray.

[0003] Examples of batch processes include electro plating, electro-less plating and hot-dipped galvanization. Common plating alloys are chromium and nickel used for corrosion, wear, and heat-resistant applications. Common galvanization processes include applying zinc to steel for inexpensive corrosion protection. Batch processing has the advantages of high throughput for economies of scale, but, in the case of electro and electro-less plating, the disadvantages of high costs associated with plating chemicals and the environmental impact of disposing of the plating chemicals. In particular, chrome plating is desired for its hardness and corrosion resistance, but the hexavalent chrome found in the plating bath is facing ever-more stringent environmental restrictions, with the ultimate objective of phasing it out altogether.

[0004] In order to coat a substrate with a coating of substantially the same or similar base chemical composition, electro-chemical or electro-less techniques were previously used. In these prior techniques, the coating material is placed into a chemical solution to create a plating bath, the substrate is then introduced into the plating bath, and coating occurs by either the application of electricity to the system (electro-plating) or through a chemical reaction (electro-less deposition). The final atomic structure is usually poly-crystalline, but thin amorphous films can be formed by certain electro-less nickel techniques. [0005] Hot dipped galvanizing techniques are utilized when the coating material is substantially different in chemical composition to the underlying substrate to be coated. Typically, the coating material comprises zinc, which functions as a sacrificial anode designed to preferentially corrode over time in relation to the substrate. Additionally, zinc is a relatively soft material and relatively "dirty" in the sense that it smudges hands, clothing or other surfaces that come into contact with it. In sum, zinc provides limited protection over the life of the underlying substrate and is not well-suited as a coating for devices or articles that are handled often or require resistance to wear. In contrast, stainless steel, for example, has a high chrome content that oxidizes and forms a chrome oxide that forms a relatively permanent protective barrier against further oxidation and corrosion.

[0006] As an alternative coating method, cladding techniques have been employed to provide coatings on substrates in which the coating material and the substrate material are of substantially the same chemical composition. This process involves welding or bonding thin solid sheets of the coating material onto the desired base material. The coating material and the base metal can be of substantially the same composition, but often they are not depending on the intended application. Vapor deposition in which the coating material is first vaporized then deposited onto the substrate under vacuum inside a closed chamber is another technique that has been used.

[0007] "Sequential single" (e.g., spray) processes have been developed in order to address some of the shortcomings of the batch/bath processes. Sequential single processes are typically used for applications of novel coatings with superior hardness, wear, and or corrosion properties which are not amenable to batch techniques. Examples of such processes include the various spray techniques in which the coating material is first formed into a powder of 15 to 100 microns, for example, depending on the specific spray process chosen. The powder is then loaded into a spray gun, melted, and then shot through the specially designed spray gun as the gun is raster scanned across the substrate. In alternative methods, the coating material is provided in the form of a wire, which is fed into a specially designed spray gun, where it is melted and then sprayed onto a substrate. The wire feed method is essentially the same as the powder method - except the powdered material is formed into wires to be accommodated by the equipment of choice. In some applications, an under-coating material can be applied to enhance bonding between the coating and the substrate.

[0008] Common sequential processes are known as High Velocity Oxygen Fuel

(HVOF) and Plasma processes. These processes are amenable to having a coating and substrate made of substantially the same base chemical composition. However, temperatures of the melted metallic coating droplets leaving the spray gun are typically in excess of 1500 ° C for HVOF and 6000 ° C for plasma processes. These droplets cool at a rate of greater than 1 million degrees centigrade per second, and travel at velocities as high as 7000 feet per second (213Kcm/s) as they approach the substrate. Temperatures on the substrate typically range from 38 - 150 ⁰ C. Spot size is typically less than 1 cm, depending on the gun-substrate distance and other controllable parameters inherent in the process of choice. Equipment for these processes is expensive, at around $100,000 per industrially-capable spray gun, and, while they can spray at a rate of 0.5 to 25 pounds (0.22 - 11 kg) per hour, they may still be more expensive per area when compared to chemical batch processing since one gun can only spray one substrate at a time. Additionally, each gun is controlled by a single human operator or expensive automated robots, which adds significant costs.

[0009] Processing a desired coating alloy into powder is expensive - it varies from 5-30 times the cost of the alloy material itself depending on raw materials costs of the alloy itself - due to expensive gas atomization or plasma processing used to make the powder. Such processes typically have yields of about 25-45% per pound of starting material due to size distribution and morphology of the final powders. Not all sizes and morphologies can be reliably fed through the commercially available spray equipment. Final atomic structures can be either poly-crystalline or amorphous, depending on choice of starting alloy, with conversion from amorphous to nano-crystalline sometimes occurring. Processing costs associated with spray techniques range from 5-10 times the cost of the powder material itself.

[0010] For both the batch and sequential sequence processes, care must be taken not to expose the substrate to temperatures that could damage the crystalline structure of the substrate. Moreover, the cost of the batch and sequential sequence processes are substantial. Therefore, there is a need for systems and methods that provide an alternative to the existing ways of coating substrates. Summary of the Invention

[0011] A substrate coating technology for coating a substrate with a coating material having a substantially similar base composition as the material composing the substrate is disclosed. The chemical composition of the coating materials is selected to have a melting temperature substantially lower than the melting temperature of the substrate such that the coating material exhibits deep eutectic properties when compared to the substrate. The chemical composition allows the molten coating material to be applied to the substrate by dipping the substrate or pouring onto the substrate, at a temperature that will not substantially change the micro-structure of the substrate.

[0012] A first embodiment comprises a method for coating a substrate. The method comprises providing a coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate, and melting the coating material to obtain a molten coating material. The method further comprises coating the substrate with the molten coating material.

[0013] A second embodiment comprises an apparatus for coating a substrate. The apparatus comprises a vessel for containing a molten coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate. The apparatus further comprises a dipping device for dipping the substrate in the molten coating material.

[0014] A third embodiment comprises an apparatus for coating a substrate. The apparatus comprises means for coating the substrate with a coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate. The apparatus further comprises a pouring device for pouring the molten coating material, and a means for moving the substrate under the pouring device.

[0015] A fourth embodiment comprises an apparatus for coating a substrate. The apparatus comprises means for coating the substrate with a coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate. The apparatus further comprises means for moving the coated substrate through a heating zone and a quenching zone. The apparatus also includes, a heating source for re-melting the coating material on the coated substrate, and a quenching source for quenching the coated substrate. [0016] A fifth embodiment comprises a method for coating a substrate. The method comprises providing a coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate. The method further comprises melting the coating material and coating the substrate with an intermediate layer which has a crystal structure different than crystalline allotropes of the molten coating material. The method further comprises coating the intermediate layer with the molten coating material.

[0017] Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings.

Brief Description of the Drawings

[0018] The present disclosure, in accordance with one or more various embodiments, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the disclosure. These drawings are provided to facilitate the reader's understanding of the disclosure and should not be considered limiting of the breadth, scope, or applicability of the disclosure. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale.

[0019] Figure 1 shows an exemplary flow diagram illustrating a low cost substrate coating process in accordance with an embodiment of the invention.

[0020] Figure 2 is an illustration of an exemplary system for dipping a substrate into a vessel containing molten coating material in accordance with an embodiment of the invention.

[0021] Figure 3 is an illustration of an exemplary system for pouring molten coating material onto a substrate in accordance with an embodiment of the invention.

[0022] Figure 4 is an illustration of an exemplary re-melting and quenching system in accordance with an embodiment of the invention. Detailed Description of the Exemplary Embodiments

[0023] In the following description of exemplary embodiments, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific embodiments in which the disclosure may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the exemplary embodiments of the invention.

[0024] The present disclosure is directed toward systems and methods for providing low cost substrate coating. Embodiments of the invention are described herein in the context of one practical application, namely, coating a steel substrate. Embodiments of the invention, however, are not limited to such steel substrate coating applications, and the methods described herein may also be utilized in other applications such as coating aluminum. As would be apparent to one of ordinary skill in the art after reading this description, these are merely examples and the invention is not limited to operating in accordance with these examples.

[0025] Embodiments of the invention provide a method of coating substrates with a coating material having a substantially similar base composition as the substrate material. As used herein, "substantially similar base composition" means that the coating material consists of at least 30% by weight of the dominant base element of the substrate. The dominant base element of the substrate is an element that makes up at least 50% by weight of the substrate material. For example, if the substrate to be coated is made up of 60% iron, 20% chrome, 10% nickel, and 10% of other alloy elements, then iron is the dominant base element of the substrate. A coating material having a substantially similar base composition would comprise at least 30% iron by weight with no other element comprising an equal or higher percentage by weight of the composition.

[0026] In the following description of preferred embodiments, reference is made to the accompanying Figures which form a part hereof, and in which it is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the preferred embodiments of the present invention.

[0027] Figure 1 shows an exemplary flow diagram illustrating a low cost substrate coating process 100 according to an embodiment of the invention. The various tasks performed in connection with process 100 may be performed by hardware, and software, firmware, a computer-readable medium having computer executable instructions for controlling and operating the process method, or any combination thereof. It should be appreciated that process 100 may include any number of additional or alternative tasks, the tasks shown in Figure 1 need not be performed in the illustrated order, and process 100 may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein.

[0028] The low cost substrate coating process 100 may begin by providing a deep eutectic coating material (task 102). The coating material may comprise at least 55% by weight of the dominant base element of the substrate. The chemical composition of the coating materials is further selected so that the melting temperature of the coating material is substantially lower than the melting temperature of the substrate such that the coating material exhibits deep eutectic properties when compared to the substrate. In this way, when the substrate is dipped into the molten coating material or when the molten coating is poured onto the substrate, the temperature of the molten coating will not substantially change the micro- structure (e.g., amorphous, poly-crystalline, nano- crystalline, or melt the surface, etc.) of the substrate.

[0029] The low cost substrate coating process 100 may then continue with melting the deep eutectic coating material (task 104). The melting temperature of the coating material may be selected by taking into consideration one or more factors such as (1) the desired microstructure (e.g., amorphous, poly-crystalline or nano-crystalline) and thickness of the resulting coating layer; (2) volume of the substrate compared to the volume of the coating material; (3) amount of time substrate is maintained in the molten coating material; and (4) the melting temperature of the substrate. Taking these factors into account, the coating material should exhibit deep eutectic properties with respect to a selected substrate having a substantially similar base composition as the coating material such that the coating will not substantially change the microstructure or melt the surface of the substrate when applied, either via dipping or pouring, to the substrate.

[0030] In one embodiment, the chemical composition of the coating material is selected so that it has a melting temperature of at least 100° C less than that of the substrate. In a further embodiment, the melting temperature of coating material is selected to be at least 300° C less than that of the substrate. In another embodiment, the melting temperature of coating material is selected to be at least 500° C less than that of the substrate. In a further embodiment, the melting temperature of the coating material is selected to be at least 25% to 40% lower than the melting temperature of the substrate.

[0031] The low cost substrate coating process 100 may then continue with coating the substrate with deep eutectic coating material (task 106). The coating material may be applied to the substrate by either dipping the substrate into a vessel or bath containing molten coating material or pouring the coating material onto the substrate. In either method, the substrate acts substantially as the quenching agent for the molten coating material, that is, heat is removed from the molten coating material during solidification primarily through the substrate. In various embodiments, the substrate temperature can be allowed to "float" at ambient, or cooled during or shortly after processing to achieve a desired cooling rate.

[0032] The coating material's chemical composition may have substantially the same base composition as the substrate but have additional alloying elements that give rise to deep eutectic behavior. Successive layers of coating material can be applied, and the atomic structure of the coating material can be controlled by either the initial coating process or by subsequent processing to be either substantially amorphous, a mixture between amorphous and nano- or poly-crystalline, or substantially nano- or poly- crystalline. The novel coating process of the present invention results in approximately 50-70% coating materials preparation cost savings (e.g., there is no requirement to turn material into a powder form). Additionally, the present invention eliminates costly equipment requirements and consumable materials (e.g., gases in spray processes, plating chemicals in plating processes, etc.) associated with prior spraying and plating processes.

[0033] In this manner, coatings having a substantially similar base composition as that of the substrate can be applied, resulting in coatings having a desired atomic structure from substantially amorphous, partially amorphous/partially nano- or poly-crystalline, to substantially all nano- or poly-crystalline depending on the final desired properties. Such coating and substrate materials include, but are not limited to, steel, aluminum, gold and titanium alloys.

[0034] In one embodiment, the substrate may be made of commercially available steel alloy coated with a coating alloy composition comprising approximately 55% by weight of iron, and approximately 7% chromium, 20% molybdenum, 2% carbon, 3% boron, 10% tungsten, and 0.5% silicon (the "coating alloy"). This coating alloy composition has a eutectic (melting) temperature of approximately 1100° C versus approximately 1530° C for the base steel substrate. The molten coating alloy may be prepared in a vessel with a volume of approximately 50 cm³. A substrate of a high strength steel bar (substantially same base chemical composition as the coating alloy) with a volume of approximately 12.5 cm³ may be first sandblasted and rinsed in acetone to remove surface scale residues. The substrate can then be drawn through the molten coating alloy at a rate of approximately 4 - 5 cm/s.

[0035] After cooling, x-ray diffraction and microscopy analytical techniques may be performed, and may reveal, for example, that the solidified coating alloy was 0.02 cm (0.008") thick and a mixture of approximately 60-70% amorphous or nano-crystalline and 30-40% poly-crystalline structures. A thin layer at the coating-substrate interface, comprising less than about 5% of the total thickness of the coating layer, may be poly- crystalline, followed by about 65% of the thickness being amorphous, and the final outer 35% of the thickness may be poly-crystalline. Hammer impact tests can show extremely high bonding strength of the coating to the substrate.

[0036] The above steps may be repeated with a commercially available zinc galvanized steel pipe used as the substrate, having a volume of approximately 4 cm³. Thus, in effect, an additional step of coating a commercial steel substrate with an intermediate zinc coating layer via a hot-dipped galvanization process, can be added. The above-described coating alloy can then be applied on top of the galvanized zinc layer, in the manner described above.

[0037] Analysis of the microstructure of the resulting outer steel coating layer revealed absence of the thin poly-crystalline layer at the interface, with the rest of the microstructure substantially 100% amorphous or nano-crystalline, approximately 0.02 cm (0.008") thick. Thus, the Zn-coating suppressed crystal formation of the Fe-based coating alloy and thus helped to control or effect the atomic structure of the applied Fe-based coating alloy. In alternative embodiments, other material compositions (e.g., Al, Cu, Ni, C, Sn, Si, etc.) can be used as an intermediate layer.

[0038] Figure 2 is an illustration of an exemplary system 200 for dipping a substrate into a vessel containing molten coating material in accordance with an embodiment of the invention. System 200 comprises a substrate 202, a molten coating material 204, a containment vessel 206, and heating coils 208/210/212/214. System 200 also comprises a dipping device 216 for holding and dipping the substrate into the molten material. In the illustrated example, the substrate 202 is comprised of steel, which comprises iron as its dominant base element (i.e., greater than 50% by weight).

[0039] As discussed above, it is desirable to select a molten coating material 204 that exhibits deep eutectic properties with respect to the substrate 202 or, in other words, has a melting temperature that is less than that of the substrate 202 so as to not substantially alter the microstructure of the substrate 202 when it is applied onto the substrate 202. In one embodiment, the molten coating material 204 can be selected and designed in accordance with the material compositions disclosed in co-pending application serial no. 11/628,574, entitled "Low Cost Amorphous Steel," filed on December 4, 2006, the entirety of which is incorporated by reference herein. The chemical composition of the molten coating material 204 will affect its melting temperature. Therefore, a material composition having a desired melting temperature can be selected from commercially available compositions. It will be understood, however, that other material compositions may be selected and utilized in accordance with the present invention. In one embodiment, the molten coating material 204 has a substantially similar base composition as the substrate 202. Thus, in this example, the molten coating material 204 would comprise at least 30% iron by weight.

[0040] The molten coating material 204 is melted within the containment vessel

206 via the heating coils 208/210/212/214 which heat the containment vessel 206 to a desired temperature. The dipping device 216 dips the substrate 202 into the molten coating material 204 in or under an inert atmosphere to prevent oxidation of the molten coating material 204. Alternatively, a flux or slag may be employed to prevent excessive oxygen contamination of the molten coating material 204 during the coating process. The dipping device 216 may also be used to remove the substrate 202 for curing or other purposes.

[0041] In one embodiment, the invention provides a method for coating a substrate with a coating material of substantially the same base chemical composition as the substrate to be coated. In one embodiment, the coating material alloy composition is selected to include a base alloy element that comprises at least 30% by weight of the coating material, and which is the same as the base alloy element of the substrate. In another embodiment, the coating material comprises at least 55% by weight of the base alloy element. The coating material further has a melting temperature of at least 100° C less than the melting temperature of the substrate. Coating alloy compositions that have eutectic temperatures (melting temperatures) of several hundred degrees less than other alloy compositions having the same dominant base element often exhibit amorphous structures when cooled faster than a predetermined cooling rate (e.g., greater than 100⁰ C per second).

[0042] Figure 3 is an illustration of an exemplary system 300 for pouring molten coating material onto a substrate in accordance with an embodiment of the invention. System 300 comprises a substrate 302, a molten coating material 304, a containment vessel 306, a pouring device 308, a transport device 310 for moving the substrate under the pouring device 308 and a rotating device 312 for rotating the substrate under the pouring device 308.

[0043] The substrate 302 and molten coating material 304 may be as mentioned above in the context of discussion of Figure 2. The molten coating material 304 is held in containment vessel 306 and may be pumped through a pipe 316 to pouring device 308 to be poured on substrate 302.

[0044] The substrate 302 is moved by a substrate moving device 310 under the pouring device 308. The substrate 302 may be moved longitudinally under a molten coating material stream 318 from the pouring device 308 to coat the substrate 302. The molten coating material 304 may be poured onto the substrate 302 in or under an inert atmosphere to prevent oxidation of the molten coating material 304 during pouring. Alternatively, a flux or slag may be employed to prevent excessive oxygen contamination of the molten coating material 304 during the coating process.

[0045] A substrate rotating device 312 may also be used to rotate the substrate

302 as it travels in the longitudinal direction to insure that all sides of the substrate 302 are coated. As the substrate 302 moves through the molten coating material stream 318, a coated substrate 314 is produced. The molten coating material 304 may be applied to the substrate 302 (either via dipping or pouring) at a rate of approximately ten to one hundred feet per minute for industrial processing. However, it is understood that in other embodiments, the rate can be more or less than this depending on other process parameters (e.g., desired microstructure of coating layer, composition of coating layer, geometry of substrate, melting temperatures of substrate and coating material, etc.). This is a more efficient process than prior art techniques. For example, in prior spray processes, the molten coating alloy is superheated by gases to temperatures far in excess of the melting temperature of the alloy. The molten coating alloy is not a contiguous liquid, but rather individual droplets, and these droplets travel to the substrate at high velocities (e.g., near 7000 feet per second or 213Kcm per second). The plating processes require the coating material to be placed into a chemical solution. The vapor processes require the coating to be converted into vapor, and the cladding process required the coating material to be formed into solid sheets. In contrast, in the present invention, the coating alloy is merely melted in a bath and applied to the substrate by dipping the substrate into bath or pouring the coating onto the substrate at predetermined rates.

[0046] In various embodiments, the coating alloy rapidly solidifies when it contacts the substrate because the substrate acts as the primary source of heat removal from the solidifying coating alloy. The atomic structure of the coating alloy is determined by the cooling rate of the molten alloy as it solidifies. In one embodiment, the cooling rate is altered or controlled by adjusting one or more of the following parameters: the speed at which the substrate is drawn through or dipped into the coating alloy; the surface condition of the substrate, the temperature of the substrate; the temperature of the room or chamber where the coating is applied to the substrate; and the volume of the molten coating being introduced versus the volume of the substrate. For example, the longer the substrate is exposed to the molten coating bath, the slower the cooling rate will be because the substrate's temperature is increased. As another example, the greater the mass of the substrate compared to the mass of the coating applied, the faster the coating will solidify and cool.

[0047] Depending on the coating alloy composition chosen, cooling at a rate greater than 100° C per second, for example, can result in a coating that is substantially amorphous in structure, while cooling at a slower rate can result in poly-crystalline or mixed structures. These different microstructures of the coating layer may be desirable for different applications. For example, an amorphous microstructure typically results in a harder, less ductile coating layer or shell. In contrast, a poly- or nano-crystalline microstructure results in a more ductile coating layer. [0048] A thin layer of intermediate coating material (e.g., zinc) may be applied onto the substrate prior to application of the final coating material having a substantially similar base composition as the substrate. This intermediate layer serves to control or affect the resulting microstructure of the subsequent coating layer by retarding or accelerating the formation of certain atomic structures, thus serving as either a "seed" or "anti-seed" crystal. A material that is able to exist in more than one atomic configuration is said to exhibit allotropic properties. Coating alloys that have compositions that display deep eutectic behavior can solidify in more than one atomic configuration, which is controlled substantially by a combination of the cooling rate and by the atomic configuration of the solid that the coating alloy first contacts during cooling. One allotrope of such an alloy is an amorphous structure. Another is a preferred crystalline structure common to base (i.e., non-deep eutectic) alloys in the alloy family (e.g., steel). When a molten material comes into contact with a solid surface, it will tend to solidify according to the atomic structure of that solid if it is capable. Employing a thin intermediate layer of a crystal structure different than one of the preferred crystalline allotropes of the coating alloy can aid in the formation of the amorphous allotrope, providing greater flexibility in designing the cooling rate process window that results in the desired final atomic structure of the coating. Successive coating layers can be applied of varying composition-eutectic temperature alloys to achieve various coating thicknesses and properties. For example, successive coatings, each having a lower melting temperature than the previous coating or the substrate may be applied in accordance with the present invention.

[0049] Figure 4 is an illustration of an exemplary re-melting and quenching system 400 in accordance with an embodiment of the invention. The re-melting and quenching system 400 is an optional post-coating apparatus for improving the quality of the coating. The re-melting and quenching system 400 re-melts and rapidly quenches a previously applied coating or multiple coatings. System 400 comprises a coated substrate 402, a coated substrate moving device 404 (any moving device known in the art such as a conveyer belt can be used ) a heating source 406 for re-melting the material on the coated substrate, and a quenching source 408 for quenching the coated substrate.

[0050] The coated substrate 402 may be moved into the re-melt zone 410 of the heating source 406 by the coated substrate moving device 404. The heating source 406 re-melts the material on the coated substrate 402. The re-melting can be accomplished by passing the coated substrate 402 under a heat source such as a laser, infrared lamp, or flame torch, for example, to re-melt and further modify the final atomic structure of the coating(s).

[0051] The coated substrate 402 may be moved into the quenching zone 412 of the quenching source 408 by the coated substrate moving device 404 to quench the re- melted coated substrate 414. Rapid quenching may be achieved by using a quenching source 404 such as blowing cooled air, or inert or reactive gas, or by spraying water or other cool liquids onto the re-melted coating layer to achieve a desired cooling rate. Alternatively, if the substrate mass is large enough compared to the mass and volume of coating material, blowing cool air or liquid may not be necessary to achieve a desired cooling rate.

[0052] In this manner, coatings having a substantially similar base composition as that of the substrate can be applied, resulting in coatings having a desired atomic structure from substantially amorphous, partially amorphous/partially nano-crystalline or poly- crystalline, to substantially all nano-crystalline or poly-crystalline depending on the final desired properties. Such coating and substrate materials include, but are not limited to, steel, aluminum, gold and titanium alloys.

[0053] Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term "including" should be read as mean "including, without limitation" or the like; the term "example" is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; and adjectives such as "conventional," "traditional," "normal," "standard," "known" and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, a group of items linked with the conjunction "and" should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as "and/or" unless expressly stated otherwise. Similarly, a group of items linked with the conjunction "or" should not be read as requiring mutual exclusivity among that group, but rather should also be read as "and/or" unless expressly stated otherwise. Furthermore, although items, elements or components of the disclosure may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated. The presence of broadening words and phrases such as "one or more," "at least," "but not limited to" or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent.

Claims

WHAT IS CLAIMED IS:

1. A method for coating a substrate, the method comprising: providing a coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate; melting the coating material to obtain a molten coating material; and coating the substrate with the molten coating material to obtain a coating layer.

2. The method of claim 1, wherein the coating material has a melting point that is at least 100° C less than a melting point of the substrate.

3. The method of claim 2, wherein the coating material melting point is at least 300⁰C less than the melting point of the substrate.

4. The method of claim 2, wherein the coating material melting point is at least 500⁰C less than the melting point of the substrate.

5. The method of claim 2, wherein the coating material melting point is at least 25% to 40% less than the melting point of the substrate.

6. The method of claim 1, wherein the coating material is cooled at a rate predetermined to provide a desired microstructure, wherein the desired microstructure comprises at least one of the group consisting of amorphous, poly-crystalline, and nano- crystalline.

7. The method of claim 1, wherein the coating material comprises at least 30% by weight of a dominant base element of the substrate.

8. The method of claim 7, wherein the dominant base element of the substrate comprises an element that makes up at least 55% by weight of the substrate.

9. The method of claim 1, wherein the coating step comprises dipping the substrate in the molten coating material.

10. The method of claim 1, wherein the coating step comprises pouring the molten coating material onto the substrate.

11. The method of claim 1, wherein the substrate acts as a quenching agent for the molten coating material, thereby allowing heat to be removed from the molten coating material during solidification through the substrate.

12. The method of claim 11, wherein a substrate temperature is kept at ambient room temperature.

13. The method of claim 11, wherein the substrate is cooled during coating.

14. The method of claim 11, wherein the substrate is cooled after coating.

15. The method of claim 1, further comprising applying successive layers of the molten coating material to obtain a coating layer with a controlled atomic structure.

16. The method of claim 15, wherein the controlled atomic structure is either substantially amorphous, a mixture between amorphous and nano- or poly-crystalline, or substantially nano- or poly-crystalline.

17. The method of claim 1, further comprising forming an intermediate layer on the substrate prior to coating the substrate with the coating material, wherein the intermediate layer comprises an atomic structure that is different than that of the substrate such that the coating layer comprises an atomic structure that is different than that of the substrate.

18. The method of claim 17, wherein a thickness of the poly-crystalline layer is less than about 5% of a thickness of the coating layer, a thickness of the inner amorphous layer is about 65% of the thickness of the coating layer, and a thickness of the outer poly-crystalline layer is about 35% of the thickness of the coating layer.

19. The method of claim 1, further comprising coating the substrate with an intermediate layer prior to applying the molten coating material.

20. The method of claim 19 wherein the intermediate layer comprises at least one of the group consisting of Zinc, Aluminum, Copper, Nickel, Carbon, Tin, and Silicon.

21. The method of claim 20, further comprising applying the molten coating material on top of the intermediate layer.

22. An apparatus for coating a substrate, the apparatus comprising: a vessel for containing a molten coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate; and a dipping device for dipping the substrate in the molten coating material.

23. An apparatus for coating a substrate, the apparatus comprising: a vessel for containing a molten coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate; a pouring device for pouring the molten coating material; and means for moving the substrate under the pouring device.

24. The apparatus of claim 23, further comprising means for rotating the substrate under the pouring device.

25. An apparatus for applying a coating on a substrate, the apparatus comprising: means for coating the substrate with a coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate to obtain a coated substrate; means for moving the coated substrate through a heating zone and a quenching zone; a heating source for re-melting the coating material on the coated substrate; and a quenching source for quenching the coated substrate.

26. The apparatus of claim 25, wherein the coated substrate moves sequentially through the effective range of the heating source and the quenching source.

27. A method for coating a substrate, the method comprising: providing a coating material having a substantially similar base composition to the substrate and a deep eutectic property with respect to the substrate; melting the coating material to obtain a molten coating material; coating the substrate with an intermediate layer, wherein the a crystal structure of the intermediate layer is different than crystalline allotropes of the molten coating material; and coating the intermediate layer with the molten coating material.

28. The method of claim 27, further comprising applying successive molten coating layers of varying composition-eutectic temperature alloys to achieve various coating thicknesses and properties.

29. The method of claim 28, wherein each of the successive molten coating layers has a lower melting temperature than a previous molten coating layer .

30. The method of claim 27 wherein the intermediate layer comprises at least one of the group consisting of: Zinc, Aluminum, Copper, Nickel, Carbon, Tin, and Silicon.