WO2022195381A1

WO2022195381A1 - Coatings and articles for impact resistant thermal barrier applications

Info

Publication number: WO2022195381A1
Application number: PCT/IB2022/051600
Authority: WO
Inventors: Dinh Ba Le; Matthew T. Johnson; Sebastian GORIS; Daniel S. BATES; Mark A. FAIRBANKS; Peter T. Dietz
Original assignee: 3M Innovative Properties Company
Priority date: 2021-03-18
Filing date: 2022-02-23
Publication date: 2022-09-22

Abstract

Coatings and articles containing the coatings that can be used as impact resistance thermal barriers in high temperature applications. The coatings comprise calcium silicate and an inorganic binder comprising an alkali silicate or a sol. The coating may optionally comprise fibers. Articles containing the coatings can be made by mixing together the calcium silicate, optionally the fibers, and either a solution of the alkali silicate or a sol to form a coating solution, applying the coating solution to at least the first major surface of a substrate, and hardening the coating solution by drying and curing the coating solution.

Description

COATINGS AND ARTICLES FOR IMPACT RESISTANT THERMAL BARRIER APPLICATIONS

BACKGROUND

An expanding market exists for hybrid or fully electric vehicles typically fueled by rechargeable batteries, such as the lithium-ion battery. Such batteries are typically made up of several battery modules, and each battery module comprises many interconnected individual battery cells. When one cell in a battery module is damaged or faulty in its operation, the temperature within the cell may increase faster than heat can be removed. If the temperature increase remains unchecked, a catastrophic phenomenon called thermal runaway can occur resulting in a fire and blasts of particles as hot as 1000°C or more. The resulting fire can spread very quickly to neighboring cells and subsequently to cells throughout the entire battery as a chain reaction. These fires can be potentially massive and can spread to surrounding structures and endanger occupants of the vehicle or structures in which these batteries are located.

SUMMARY

The present disclosure provides coatings and articles comprising such coatings that exhibit high impact resistance (i.e. resistance to damage due to particle impact) and high thermal transfer resistance at elevated temperatures (e.g., up to 1800°C). Such articles can be used, for example, as impact resistant thermal barriers in the construction of battery components to isolate fires and reduce the chance for a catastrophic thermal runaway.

In one embodiment, the present disclosure provides a coating comprising calcium silicate, and an inorganic binder comprising an alkali silicate or a sol, wherein the sol comprises a colloidal solid in a liquid.

In another embodiment, the present disclosure provides an article comprising a substrate having a first major surface and a second major surface opposite the first major surface, and a hardened coating of the present disclosure on at least the first major surface of the substrate.

In a further embodiment, the present disclosure provides a method of making the article of the present disclosure, the method comprising mixing together the calcium silicate and either a solution of the alkali silicate or a sol to form a coating solution, applying the coating solution to at least the first major surface of the substrate, and hardening the coating solution by drying and curing the coating solution.

In yet a further embodiment, the present disclosure provides a battery comprising a plurality of battery cells separated from one another by a gap, and the article of the present disclosure disposed in the gap between the battery cells.

In another embodiment, the present disclosure provides a battery comprising a compartment lid having an inner and outer major surface, the inner major surface covering a plurality of battery cells, and the article of the present disclosure disposed on the inner surface of the compartment lid.

As used herein:

The term “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims. Such terms will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements. By “consisting of’ is meant including, and limited to, whatever follows the phrase “consisting of.” Thus, the phrase “consisting of’ indicates that the listed elements are required or mandatory, and that no other elements may be present. By “consisting essentially of’ is meant including any elements listed after the phrase, and limited to other elements that do not interfere with or contribute to the activity or action specified in the disclosure for the listed elements. Thus, the phrase “consisting essentially of’ indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present depending upon whether or not they materially affect the activity or action of the listed elements.

In this application, terms such as “a,” “an,” and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terms “a,” “an,” and “the” are used interchangeably with the phrases “at least one” and “one or more.” The phrases “at least one of’ and “comprises at least one of’ followed by a list refers to any one of the items in the list and any combination of two or more items in the list.

The term “or” is generally employed in its usual sense including “and/or” unless the content clearly dictates otherwise.

The term “and/or” means one or all of the listed elements or a combination of any two or more of the listed elements.

Also herein, all numbers are assumed to be modified by the term “about” and in certain embodiments, by the term “exactly.” As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used. Herein, “up to” a number (e.g., up to 50) includes the number (e.g., 50).

Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range as well as the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

Reference throughout this specification to “some embodiments” means that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

The words “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances; however, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure.

The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments.

DETAILED DESCRIPTION

The following is a description of illustrative embodiments. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

Coatings of the present application generally comprise calcium silicate and an inorganic binder comprising an alkali silicate or a sol. In some embodiments, the coatings further comprise fibers. A coating is typically applied to one or more surfaces of a substrate and hardened by dehydration and curing. The resultant article can be used to create a high impact resistant thermal barrier that operates at temperatures as high as 1800°C. In some embodiments, the article can be used as a thermal barrier between cells in a battery, including cells in a battery module or a battery pack, to reduce the potential for catastrophic thermal runaway events. Additionally, or alternatively, the article can be used as a protective inner surface of a battery (e.g., inner surface of lid). Although the coatings and articles disclosed herein are discussed in the context of electric vehicle battery applications, it should be understood that the coatings and articles can be used in other applications desiring impact resistance and/or thermal transfer resistance at elevated temperatures.

The calcium silicate used in the coating is not particularly limiting, and can be any of a number of stoichiometric mixtures of CaO and S1O2, including calcium metasilicate (CaSiCf) and calcium orthosilicate (CaaSiCL). In some preferred embodiments, the coating comprises calcium metasilicate. Calcium silicates generally contribute to the thermal stability and insulation performance of the coating. In some embodiments, the coating comprises at least 20 wt.%, at least 25 wt.%, at least 30 wt.%, at least 40 wt.%, at least 50 wt.%, at least 60 wt.%, or at least 70 wt.% calcium silicate based upon the percentage of solids in the coating. In some embodiments, the coating comprises up to 80 wt.%, up to 76 wt.%, up to 74 wt.%, up to 72 wt.%, up to 70 wt.%, up to 65 wt.%, up to 60 wt.%, up to 55 wt.%, or up to 50 wt.% calcium silicate based upon the percentage of solids in the coating. In some embodiments, the coating comprises 20 wt.% - 80 wt.%, more particularly 40 wt.% to 80 wt.%, and even more particularly 60 wt.% to 80 wt.% calcium silicate based upon the percentage of solids in the coating. The term “solids”, as used herein in the context of percentage of solids in the coating, means the components that remain in the coating after dehydration and curing. Solvents (e.g., water) driven off during formation of the hardened coat are not considered solids. Since the solvent does not form part of the solids in the coating, the solids content will be approximately the same before and after a coating is dried and cured. The inorganic binder that makes up the coating may comprise an alkali silicate. The term “silicate”, as used herein, means a salt in which the anion contains both silicon and oxygen. Silicates include metasilicates (SiO₃ ^2-) and orthosilicate (SiO₄ ^4-). Exemplary alkali silicates include sodium silicate, potassium silicate, lithium silicate, or combinations thereof. In some embodiments, the alkali silicate is a metasilicate having the formula M₂SiO₃, wherein M is Na, K or Li. In other embodiments, the alkali silicate is a polysilicate having the formula M₂O(SiO₂)_x ^yH₂O, wherein M is selected from Li, Na, or K, x is between 1 and 15, preferably between 2 and 9, and y is > 0. In some embodiments, the alkali silicate is sodium silicate or potassium silicate. In some further embodiments, the alkali silicate is Na₂SiO₃. The choice of silicate may depend upon the desired application. For example, adhesion between the coating and a substrate can be influenced by the nature of the alkali silicate, where adhesion decreases in order of sodium silicate, potassium silicate, and lithium silicate. Therefore, in some embodiments, sodium silicate may be the preferred alkali silicate. However, coatings made with potassium silicate tend to exhibit greater moisture resistivity and may be preferable in environments where the coating may be exposed to humidity. Therefore, in some embodiments, potassium silicate may be the preferred alkali silicate. In some embodiments, the coating comprises at least 20 wt.%, at least 23 wt.%, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 50 wt.%, at least 60 wt.%, or at least 70 wt.% alkali silicate based upon the percentage of solids in the coating. In some embodiments, the coating comprises up to 80 wt.%, up to 75 wt.%, up to 70 wt.%, up to 65 wt.%, up to 60 wt.%, up to 50 wt.%, or up to 40 wt.% alkali silicate based upon the percentage of solids in the coating. In some embodiments, the coating comprises 20 wt.% - 80 wt.%, more particularly 20 wt.% - 60 wt.%, even more particularly 20 or wt.% - 40 wt.% alkali silicate based upon the percentage of solids in the coating. Alternatively, the inorganic binder that makes up the coating may comprise a sol. The term “sol”, as used herein, means a fluid suspension of a colloidal solid in a liquid. The colloidal solid can be macromolecules, oligomers, nanoparticles, or combinations thereof. Typically, the diameter of the colloidal solid ranges from 3 nm to 60 nm. The liquid is preferably water but may also include alcohols (e.g., ethanol and propanol). Sols of the present disclosure typically perform at high temperatures (e.g., above 1000°C). Exemplary colloidal solids include silica (S1O₂), titania (T1O₂), alumina (AI₂O₃), Zirconia (ZrO₂), or combinations thereof. In some embodiments, the coating comprises at least 10 wt.%, at least 15 wt.%, at least 20 wt.%, at least 23 wt.%, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 50 wt.%, at least 60 wt.%, or at least 70 wt.% colloidal solids based upon the percentage of solids in the coating. In some embodiments, the coating comprises up to 80 wt.%, up to 75 wt.%, up to 70 wt.%, up to 65 wt.%, up to 60 wt.%, up to 50 wt.%, up to 40 wt.%, or up to 30 wt.% colloidal solids based upon the percentage of solids in the coating. In some embodiments, the coating comprises 10 wt.% to 80 wt.%, more particularly 10 wt.% to 60 wt.%, even more particularly 15 wt.% to 24 wt.%, or even more particularly 16 wt.% to 24 wt.% of colloidal solids based upon the percentage of solids in the coating.

The coating of the present disclosure may optionally comprise fibers. Fibers can be used to enhance the mechanical properties of the coating, including increasing the blast or impact resistance of the coating and articles to which it has been applied. In some embodiments, where the coating is made with a sol, the fibers tend to reduce the formation of microscale cracks that can develop in the sol-based coatings during processing and/or use, which cracks tend to contribute to the weakening of the mechanical properties of the coating.

The fibers are typically made of high refractory glass or ceramic materials. A “refractory material” or “refractory”, as used herein, is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. The fibers typically have an aspect ratio ranging from 50: 1 to 500: 1. Fibers having an aspect ratio less than 50:1 behave more like a powder and provide little-to-no performance benefit. Fibers having an aspect ratio greater than 500: 1 typically have difficulty dispersing within the coating and can produce a rough (e.g., lumpy) surface coating. In some embodiments, the fibers have an average length ranging from 1/32 inch to 1/4 inch.

Exemplary fibers include E-glass fibers, S-glass fibers, R-glass fibers, ECR-glass fibers, basalt fibers, ceramic fibers, aramid fibers, polycrystalline fibers, silicate fibers, alumina fibers, silica fibers, alumina-silica fibers, carbon fibers, silicon carbide fibers, boron silicate fibers, combinations thereof. The fibers may include annealed melt-formed ceramic fibers, sol-gel formed ceramic fibers, polycrystalline ceramic fibers, glass fibers, including annealed glass fibers or non-bio-persistent fibers. Suitable commercially available fibers include 3M™ Nextel™ fibers (e.g., 610 grade fibers available from 3M Company in St. Paul, MN), 1/32” Milled Glass Fibers (available from FIBREGFAST® in Brookville, OH) and 1/8” Chopped Glass Fibers (available under Product Code 01014 from PPG Industries in Pittsburgh, PA). While glass fibers typically have lower thermal conductivity than Nextel fibers, Nextel fibers are typically a higher refractory material. Therefore, in some preferred embodiments, the fiber is a Nextel™ fiber. In some embodiments, the coatings comprises at least 1 wt.%, at least 3 wt.%, at least 5 wt.%, at least 10 wt.%, at least 15 wt.%, at least 20 wt.%, or at least 25 wt.% fibers based on the percentage of solids in the coating. In some embodiments, the coating comprises up to 30 wt.%, up to 25 wt.%, up to 20 wt.% of the fibers based upon the percentage of solids in the coating. In some embodiments, the coating typically comprises 1 wt.% to 30 wt.% fibers based on the percentage of solids in the coating. Less than 1 wt.% and the fibers provide little-to-no performance benefit. Greater than 30 wt.% tends to inhibit the flowability of the coating and result in a lumpy (i.e. not smooth) coating.

Coatings of the present application may further include optional additives. Exemplary additives include defoamers, surfactants, rheological modifiers, forming aids, pH-adjusting materials, etc. Exemplary rheological modifiers can be organic compounds, including natural or modified organic compounds selected from polysaccharides (e.g., xanthan, carrageenan, pectin, gellan, xanthan gum, diuthan, cellulose ethers such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose and hydroxyethyl cellulose), proteins and polyvinyl alcohols. In some embodiments, the rheological modifier comprises fumed silica, fumed titania, fumed alumina, or combinations thereof. In some embodiments, the coating comprises 0 wt.%, at least 0.5 wt.%, at least 1 wt.%, at least 1.5 wt.%, at least 2 wt.%, at least 2.5 wt.%, at least 3 wt.%, at least 3.5 wt.%, at least 4 wt.%, at least 4.5 wt.%, or at least 5 wt.% additives based upon the percentage of solids in the coating. In some embodiments, the coating comprises up to 10 wt.%, up to 9 wt.%, up to 8 wt.%, up to 7 wt.%, up to 6 wt.%, up to 5 wt.%, up to 4 wt.%, or up to 3 wt.% additives based upon the percentage of solids in the coating. In some embodiments, the coating comprises 0 wt.% to 10 wt.%, more particularly 0.5 wt.% to 10 wt.%, even more particularly 0.5 wt.% to 5 wt.%, and further 1 wt.% to 3 wt.% additives based upon the percentage of solids in the coating.

The above coatings can be applied to a substrate to create articles exhibiting high impact and high thermal transfer resistance in high temperature applications. The substrates are typically flame resistant and may include flame resistant paper (e.g., inorganic paper or mica-based paper), an inorganic fabric, or flame resistant boards (e.g., inorganic fiber boards or mica boards or sheets). Inorganic fabrics may comprise E-glass fibers, R-glass fibers, ECR-glass fibers, basalt fibers, ceramic fibers, silicate fibers, Nextel™ fibers, steel filaments, or combinations thereof. The fibers in the inorganic fabric may be chemically treated. The fabrics may, for example, be a woven or nonwoven mat, a felt, a cloth, a knitted fabric, a stitch bonded fabric, a crocheted fabric, an interlaced fabric, or combinations thereof. Substrates may also include flame resistant polymers, including thermoplastic resins, thermosetting resins, or glass-fiber reinforced resins (e.g., polyester). Substrates may further include metals or metal alloys, including aluminum, steel, or stainless steel. Substrates may comprise a single layer structure (e.g., sheets or foils) or a multi- layered structure comprising one or more of the forementioned materials. In embodiments where the coating comprises a sol, the substrate is preferably a porous substrate (e.g., fabric substrate) to insure adequate adhesion. Coatings comprising an alkali silicate as an inorganic binder tend to adhere more strongly to the substrate and can be used with porous or nonporous substrates.

In one method, the articles are made by mixing together the calcium metasilicate and either a solution of the alkali silicate or a sol to form a coating solution, applying the coating solution to at least the first major surface of the substrate, and hardening the coating solution by drying and curing the coating solution. The term “hardened” as used in this context means that the coating has been dried (dehydrated) and cured to form an inorganic three-dimensional network. The coating layer can be applied by spraying, brushing, knife coating, nip coating, dip coating, or the like in thicknesses of, for example, 0.1 mm to 15 mm. The coating solution is dried at a temperature of no more than 100°C (by e.g., air-convective oven, infrared or microwave). The coating solution is cured at a temperature of at least 100°C.

Articles of the present disclosure comprise a substrate and the hardened coating on at least one major surface. In some embodiments, the hardened coating encapsulates the entire substrate. The thickness of the coating will depend upon the desired application. For example, thinner coatings can be used for applications involving lower temperatures and/or lower potential particle blast forces. Thicker coatings would be used for higher temperature applications and/or higher potential particle blast forces. In some embodiments, the hardened coating has a thickness in the range of 0.1 mm to 6 mm.

In some embodiments, the article of the present disclosure can survive at least 1, at least 3, at least 4, at least 5, or at least 9 blasts of abrasive media at 1200°C, as determined by the Torch and Grit Test in the Examples. In some embodiments, the article does not thermally decompose after 10 minutes of exposure to a propane flame as determined by the Propane Torch Test in the Examples.

Articles of the present application may be used in a variety of high impact, high temperature applications. For example, articles of the present disclosure may be used as impact resistant thermal barriers disposed in the gap between battery cells in an electric vehicle battery (e.g., in a battery module or a batter pack). In addition, or alternatively, the coatings or articles of the present disclosure may be disposed on the inner surface of the casing of a battery (e.g., a battery module or a battery pack), including the inner surface of a compartment lid or the inner surface of vent passages for exhaust gas. Further, the coatings and articles of the present disclosure may be used to protect a wide variety of components used in high voltage equipment, such as busbars used for high current power distribution. EXAMPLES

Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims.

Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Materials Used in the Examples

Torch and Grit Test Method

A hydrogen/oxygen torch, a customized hydrogen/oxygen burner obtained from Bethlehem Apparatus, Hellertown, PA having a central channel for particulates and a ring of outer ports for fuel and oxidizer feeds, was first equilibrated to a designed flame temperature of 1200°C or 1400°C as measured by a thermocouple inserted into the flame cone one inch (2.54 cm) from the face of the torch. A sample panel prepared as described below in the Examples and the Comparative Examples was inserted into the flame at a distance of 2.38 inches (6.03 cm) from the torch face and simultaneously subjected to a series of blasts from a stream of 120 grit aluminum oxide abrasive media powered by a 25 psi (172.37 KPa) compressed air source aligned along the same axis as the torch. An individual grit cycle consisted of 10 seconds of grit exposure followed by a 5 second break; the hot flame was maintained throughout. This blast/rest cycle was continued until the coating penetration was observed. In all cases the coated sample side was oriented towards the flame and the number of cycles to coating failure was recorded.

Propane Torch Test Method

A sample panel prepared as described below in the Examples and the Comparative Examples was suspended inside a fume hood using a binder clip. The face of the sample was exposed to a propane flame from a standard propane torch (a hand torch cylinder Bemzomatic TX9, equipped with a classic brass torch Bemzomatic UL2317, available from Worthington Industries, Columbus, OH) with a torch-to-sample distance of approximately 1 inch (2.54 cm).

The heated area was maintained in a localized spot approximately 1.5 inches (3.81 cm) from the outer edges of the square sample for the full duration of the test. Heating was maintained until the sample either substantially melted in the heated region or 10 minutes elapsed.

Example 1 (Ex 11

A coating solution was made by mixing 190 g calcium silicate powder and 169.48 g colloidal S1O2 solution using a high shear mixer (Speedmixer DAC 600 from Flack Tek Inc., Landrum, SC).

A sample panel was made by coating the solution on both sides of an 18 cm x 18 cm piece of fiberglass fabric 2 using a rubber spatula, and then drying the coating at room temperature (22°C to 25°C) for 24 hours. The solid composition of the coating was 76 wt.% calcium silicate and 24 wt.% silica by weight, as summarized in Table 1 below. The sample panel was then coated with a thin layer of Latex EAF68 to prevent shedding, and the Latex EAF68 was dried at room temperature for 24 hours followed by drying at 150°C for 1 hour.

The Ex. 1 sample panel was subjected to the Torch and Grit Test at 1200°C. The coating survived the first blast as summarized in Table 1.

Examples 2 - 7 (Ex.2 - Ex.7)

Exs. 2-7 were prepared and tested in the same manner as Ex. 1, except that the amount and source of the components were varied, as summarized in Table 1.

Table 1.

Example 8 (Ex 8)

A coating solution was made by mixing 108.3 g calcium silicate powder, 7.5 g glass fiber 1, 85.5 g sodium silicate 1, and 8 g deionized water using a high shear mixer (Speedmixer DAC 600 from Flack Tek Inc., Landrum, SC).

A sample panel was made by coating the solution on one side of an 18 cm x 18 cm piece of fiberglass fabric 2 using a rubber spatula, drying the coated panel at room temperature (22°C to 25°C) for 24 hours, coating the other side of the panel and drying in air for 24 hours, and then drying the coated panel at 150°C in air for 2 hours. The composition of the solid coating was 72.2 wt.% calcium silicate, 5 wt.% glass fiber and 22.8 wt.% sodium silicate as summarized in Table 2. The areal mass density of the dried sample was 2822 g/m².

The Ex. 8 sample panel was subjected to the Torch and Grit Test at 1200°C. As shown in Table 3, the sample survived 12 blasts.

Example 9 (Ex.9)

A coating solution was made by mixing 108.3 g calcium silicate powder, 7.5 g glass fiber 1, 85.5 g sodium silicate 1 solution, and 8 g deionized water using a high shear mixer (Speedmixer DAC 600 from Flack Tek Inc., Landrum, SC). A multilayer sample panel was constructed of five layers arranged as follows: coating/fiberglass fabric/coating/fiberglass fabric/coating. The sample panel was made from two 18 cm x 18 cm pieces of fiberglass fabric 1 by: applying coating to one side of the first fiberglass fabric; stacking the second fiberglass fabric on top of the coated side of the first fiberglass fabric; applying coating to the side of the second fiberglass fabric opposite the first fiberglass fabric; drying the coated fabrics at room temperature (22°C to 25°C) for 24 hours; coating the uncoated side of the first fiberglass fabric; and, drying the sample panel at room temperature for 24 hours followed drying at 150°C for 2 hours. The solid composition of the coating was 72.2 wt.% calcium silicate, 5 wt.% glass fiber and 22.8 wt.% sodium silicate, as summarized in Table 2. The areal mass density of the dried sample was 2920 g/m².

The sample was subjected to the Torch and Grit Test at 1200°C. As shown in Table 3, the sample survived 12 blasts.

Example 10 (Ex 101

A coating solution was made by mixing 210 g calcium silicate powder, 15 g glass fiber 1, 156.18 g sodium silicate 2 solution, and 60 g deionized water using a high shear mixer (Speedmixer DAC 600 from Flack Tek Inc., Landrum, SC).

A sample panel was made by hand spread coating the solution on aluminum plate 1 using a 3/8-inch (0.92 cm) diameter stainless steel metal tube with a coating gap of 1.37 mm, and then drying the coating in air at room temperature (22°C to 25°C) for 12 days. The solid composition of the coating was 70 wt.% calcium silicate, 5 wt.% glass fiber and 25 wt.% sodium silicate, as summarized in Table 2. The areal mass density of the dried coating was 1523 g/m².

The sample panel was subjected to Torch and Grit Test described above at 1200°C. The aluminum plate did not melt, and the coating still covered the aluminum plate after being exposed to 1200°C flame and 12 blasts, as shown in Table 3.

Examples 11 and 12 (Ex 11 and Ex 121

Ex.11 and Ex.12 were prepared and tested in the same manner as Ex.10, using the components and conditions set forth in Table 2.

The Ex.11 and Ex.12 sample panels were subjected to the Torch and Grit Test at 1200°C and 1400°C, respectively. Results are shown in Table 3.

Examples 13-17 (Ex 13 - Ex 171

Exs. 13-17 were prepared and tested in the same manner as Ex.10, using the components and conditions set forth in Table 2. The Exs.13-17 sample panels were dried several days before being subjected to the Propane Torch Test. Sample dry times and Propane Torch Test results are summarized in Table 3.

Example 18 (Ex 181

Ex. 18 was prepared in the same manner as Ex. 10, except that the amount and source of the components, coating thickness and drying times were varied as summarized in Table 2 and the coating was applied to a phenolic plate, as opposed to an aluminum plate, and dried at room temperature for several days.

The sample panel was subjected to Torch and Grit Test and the results summarized in

Table 3.

Example 19 (Ex 191

A coating solution was made by mixing 163 g calcium silicate powder, 204 g sodium silicate 3 solution, and 10 g deionized water using a high shear mixer (Speedmixer DAC 600 from Flack Tek Inc., Landrum, SC).

A sample panel was made by coating an aluminum plate to a thickness of 1.27 mm (“aluminum plate 2”) by the means of a paint sprayer (Wagner Control Spray 250, obtained from W. W. Grainger, Lake Forest, IL). The spray application was done manually in several passes to achieve a uniform coating on the aluminum plate. The sprayed coating was dried in air at room temperature (22°C to 25°C) for 7 days, followed by additional drying in a convection oven at 85°C for 48 hours.

The sample panel was subjected to the Torch and Grit test at 1400 °C. The solid composition of the coating was 65 wt.% calcium silicate and 35 wt.% sodium silicate as summarized in Table 2. The areal mass density of the dried coating was 577 g/m².

Examples 20 (Ex 201

Ex. 20 was prepared and tested in the same manner as Ex. 19, except that the amount and source of the components, coating thickness and drying times were varied as summarized in Table 2

Examples 21 - 22 (Ex 21 - 22)

Ex. 21 - 22 were prepared and tested in the same manner as Ex. 19, except that the amount and source of the components, coating thickness and drying times were varied and fumed silica 1 and fumed silica 2 were added, respectively, as summarized in Table 2. Examples 23 - 24 (Ex. 23 - 241

Ex. 23 and Ex. 24 were prepared and tested in the same manner as Ex. 19, except that the amount and source of the components, coating thickness and drying times were varied, and the coating was applied to the panel substrate using a handheld sprayer (3M™ Performance Spray Gun 26832 using a 3M™ PPS™ Type H/O Pressure Cup, and a 2.0 mm 3M™ Performance

Gravity HVLP Atomizing Head; all obtained from 3M Company, St. Paul, MN), as summarized in Table 2.

Comparative Example A (CEx A) CEx. A was a blank aluminum plate-2 without any coating applied.

Comparative Example B (CEx B)

CEx. B was a blank phenolic plate without any coating applied.

Thus, the present disclosure provides, among other things, coatings and article containing the coating that can be used in high temperature applications where impact resistance and/or thermal transfer resistance are desired. Various features and advantages of the present disclosure are set forth in the following claims.

Claims

CLAIMS What is claimed is:

1. A coating comprising: calcium silicate; and an inorganic binder comprising an alkali silicate or a sol, wherein the sol comprises a colloidal solid in a liquid.

2. The coating of claim 1, wherein the coating comprises 20 wt.% - 80 wt.% calcium silicate based upon the percentage of solids in the coating.

3. The coating of claim 1 or claim 2, wherein the alkali silicate comprises sodium silicate, potassium silicate, lithium silicate, or combinations thereof.

4. The coating of any one of the preceding claims, wherein the alkali silicate is an alkali metasilicate having the formula M2S1O3, wherein M is Na, K or Li.

5. The coating of any one of claims 1 - 3, wherein the alkali silicate is a polysilicate having the formula IVLOiSiCLLwtLO. wherein M is selected from Li, Na, or K, and x is between 1 and 15, and y is > 0.

6. The coating of any one of the preceding claims, where the coating comprises 20 wt.% - 80 wt.% alkali silicate based upon the percentage of solids in the coating.

7. The coating of any one of the preceding claims, wherein the sol comprises silica, titania, alumina, zirconia, or combinations thereof.

8. The coating of any one of the preceding claims, wherein the size of the colloidal solid ranges from 3 nm to 60 nm in diameter.

9. The coating of any one of the preceding claims, wherein the coating comprises 10 wt.% to 80 wt.% of colloidal solids based upon the percentage of solids in the coating.

10. The coating of any one of the preceding claims, further comprising fibers.

11. The coating of claim 10, wherein the coating comprises 1 wt.% to 30 wt.% fibers.

12. The coating of claim 10 or claim 11, wherein the fibers have an average length ranging from 1/32 inch to 1/4 inch.

13. The coating of any one of claims 10 - 12, wherein the fibers have an aspect ratio ranging from 50:1 to 500:1.

14. The coating of any one of claims 10 - 13, where the fibers comprise E-glass fibers, S- glass fibers, R-glass fibers, ECR-glass fibers, basalt fibers, ceramic fibers, polycrystalline fibers, silicate fibers, alumina fibers, silica fibers, alumina-silica fibers, carbon fibers, silicon carbide fibers, boron silicate fibers, or combinations thereof.

15. The coating of any one of the preceding claims, further comprising defoam ers, surfactants, rheological modifiers, forming aids, pH-adjusting materials, or combinations thereof.

16. The coating of any one of the preceding claims, further comprising rheological modifiers comprising fumed silica, fumed titania, fumed alumina, or combinations thereof.

17. An article comprising: a substrate having a first major surface and a second major surface opposite the first major surface; and a hardened coating of any one of the preceding claims on at least the first major surface of the substrate.

18. The article of claim 17, wherein the substrate comprises flame resistant paper, an inorganic fabric, flame resistant boards, thermoplastic resins, thermosetting resins, glass-fiber reinforced resins, metals, or combinations thereof.

19. The article of claim 17 or claim 18, wherein when the hardened coating comprises colloidal solid, the substrate comprises a porous material.

20. The article of any one of claims 17 - 19, wherein the hardened coating has a thickness that ranges from 0.1 mm to 6 mm.

21. A method of making the article of any one of claims 17 - 20, the method comprising: mixing together the calcium silicate and either a solution of the alkali silicate or a sol to form a coating solution; applying the coating solution to at least the first major surface of the substrate; and hardening the coating solution by drying and curing the coating solution.

22. The method of claim 21, further comprising mixing fibers together with the calcium silicate and either the solution of alkali silicate or sol to form the coating solution.

23. The method of claim 21 or claim 22, where the coating solution is applied to the substrate by spraying, brushing, knife coating, nip coating, or dip coating.

24. The method of any one of claims 21 - 23, wherein the coating solution is dried at a temperature of no more than 100°C.

25. The method of any one of claims 21 - 24, wherein the coating solution is cured at a temperature of at least 100°C.

26. A battery comprising: a plurality of battery cells separated from one another by a gap; and the article of any one of claims 17 - 20 disposed in the gap between the battery cells.

27. A battery comprising: a compartment lid having an inner and outer major surface, the inner major surface covering a plurality of battery cells; and the article of any one of claims 17 - 20 disposed on the inner surface of the compartment lid.