Fire-resistant articles and compositions

Abstract

The present invention provides a refractory article for use in a feeder system in metal casting, and a composition for making the refractory article, the composition comprising a particulate refractory material, an oxidizing fuel, an oxidizer, a sensitizer, and a binder, the composition comprising 0.5 to 5 weight percent CaSO. 4 Includes.

Description

[Technical field]

[0001] The present invention relates to refractory articles for use in metal casting, and compositions for use in making said refractory articles. In particular, the present invention relates to fluorine-free compositions and refractory articles for use in metal casting, such as feeder sleeves. [Background technology]

[0002] In a typical casting process, molten metal is poured into a pre-formed mould cavity that defines the shape of the casting. As the molten metal cools and solidifies, it shrinks, causing shrinkage cavities that result in unacceptable defects in the final casting. This is a well-known problem in the casting industry and is addressed by the use of feeders or risers integrated into the mould. Each feeder provides an additional (usually enclosed) volume or cavity that communicates with the mould cavity, allowing molten metal to enter the feeder cavity from the mould cavity during casting. During solidification of the casting, the molten metal in the feeder cavity flows in the reverse direction back into the mould cavity to compensate for the shrinkage of the casting.

[0003] For the casting to be properly fed and for voids created during metal shrinkage to be filled, the metal contained in the feeder cavity needs to remain molten for a longer period of time than the metal in the mould cavity. For this reason, the feeder system is usually provided with a feeder sleeve made from a highly insulating refractory material to reduce heat loss of the metal in the feeder cavity and ensure that it remains molten for a longer period of time. Alternatively, an exothermic feeder sleeve may be provided to actively heat the metal in the feeder cavity.

[0004] Exothermic sleeves utilize the thermite reaction, where an oxidizable fuel (usually a metal such as aluminium) is oxidized by an oxidizer (typically iron oxide, manganese dioxide, potassium nitrate or a combination thereof) to generate heat at a similar temperature to the molten metal. The thermite reaction is initiated by the heat of the molten metal as it enters the feeder cavity and comes into contact with the fuel and oxidizer.

[0005] Exothermic feeder sleeves are advantageous in that they allow the use of much smaller feeders for a given feeder application or type of casting. This has the advantage that it reduces the amount of metal wasted in the feeder, reduces the complexity of the castings that can be produced and reduces the number of castings that can be produced per mould. Over the years, a great deal of effort has been put into optimising exothermic feeder sleeves. Important parameters that are typically considered when assessing a new exothermic sleeve are the time to ignition, the maximum temperature reached (T max ), and the duration of the exothermic reaction (burn time). Increasing the amount of fuel and / or oxidizer does not necessarily increase the duration of the exothermic reaction. In many cases, not all of the fuel is consumed, so it may not be economical or practical to increase the fuel or oxidizer loading. To improve the efficiency of exothermic sleeves, sensitizers or initiators have been developed that reduce the energy required to start the exothermic thermite reaction.

[0006] In the foundry industry, potassium cryolite (K 3 AIF 6 ) and sodium cryolite (Na 3 AIFe 6Fluoride-based initiators / sensitizers such as fluor ...

[0007] US Patent No. 6,360,808 discloses compositions in which the reduction of fluoride levels is achieved by using aluminum dross as both the aluminum and fluoride source. US Patent Application Publication No. 2009 / 0199991A1 discloses compositions containing metallocenes that can reduce fluoride levels. US Patent No. 5,180,759 discloses the use of fluorinated organic polymers to reduce the total fluoride content of exothermic compositions. EP Patent No. 1,543,897B1 and US Patent No. 6,972,059B1 both disclose fluoride-free compositions. This uses magnesium as an initiator, but magnesium is highly reactive, which creates difficulties in the manufacture and processing of exothermic mixtures.

[0008] For feeder sleeves manufactured by the slurry route, the need to use insoluble materials makes it difficult to obtain technically viable alternatives to fluoride sensitisers.Certain Group II chlorides which could be used as alternatives to insoluble fluoride salts may exhibit the required insolubility but are known to be less effective as sensitisers and are unable to meet the necessary performance requirements.

[0009] The present invention was developed with these problems in mind. Summary of the Invention

[0010] In a first aspect of the present invention, there is provided a composition for producing a refractory article for use in metal casting. The composition comprises a particulate refractory material, an oxidisable fuel, an oxidant, a sensitiser and a binder. The composition comprises 0.5-5 wt. % CaSO 4 Includes.

[0011] In some embodiments, the refractory composition comprises 0.5-3 wt. % or 1-2 wt. % CaSO. 4 Includes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The composition of the present invention contains calcium sulfate (CaSO 4 ), which acts primarily as a sensitizer and also as an oxidizer. CaSO 4 The use of as a sensitizer decreases the ignition time and / or increases the combustion efficiency of the exothermic thermite reaction, thereby reducing or eliminating the use of fluoride sensitizers. Reducing the amount of fluoride sensitizer reduces fluorine contamination in the molding sand, thereby mitigating environmental and cost issues associated with the disposal of fluorine-contaminated sand and preventing the accumulation of fluorine in recycled molding sand, which can cause casting defects. In some embodiments, the composition includes an oxidizer and / or a sensitizer in addition to calcium sulfate.

[0013] It will be understood that in the context of the present invention, the terms "sensitizer" and "initiator" may be used interchangeably and are used to refer to a substance that reduces the energy required to initiate an exothermic thermite reaction.

[0014] In some embodiments, the composition contains 4.0% by weight or less, 3.5% by weight or less, 3% by weight or less, 2.5% by weight or less, 2% by weight or less, 1.5% by weight or less, 1.25% by weight or less, 1.0% by weight or less, 0.5% by weight or less, or 0.25% by weight or less of a sensitizer that is not calcium sulfate.

[0015] In some embodiments, the composition comprises 4.0 wt% or less, 3.5 wt% or less, 3 wt% or less, 2.5 wt% or less, 2 wt% or less, 1.5 wt% or less, 1.25 wt% or less, 1.0 wt% or less, 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, 0.2 wt% or less, 0.1 wt% or less, or 0.05 wt% or less of fluorine. In some embodiments, the composition is substantially free of fluorine, i.e., the composition contains no more than trace amounts of fluorine. Because fluorine compounds can be undesirable for casting quality and environmental reasons, it is preferred to contain as little fluorine as possible in the composition to maintain the desired properties of the thermite reaction.

[0016] In a preferred set of embodiments, the composition comprises a water-insoluble fluorine compound. In some embodiments, the composition is free of fluorine or is substantially free of water-soluble fluorine. The inventors have found that water-insoluble fluorine compounds can also act as sensitizers. Water-insoluble fluorine compounds are particularly preferred because they do not contaminate the moulding sand with fluorine (or fluorine compounds), for example, during mould reclamation after the refractory article formed from the composition is used in a metal casting process.

[0017] In a preferred set of embodiments, the sensitizer is calcium fluoride (CaF 2 Calcium fluoride is a water insoluble mineral that has been found to act as a sensitizer in the thermite reaction. Without wishing to be bound by theory, it is believed that calcium fluoride acts, at least in part, catalytically to inhibit the formation of an oxide layer on aluminum metal. In some embodiments, the sensitizer is magnesium fluoride (MgF 2 ).

[0018] It will be understood that the term "fluorine" as used herein is intended to refer to any compound that contains fluorine in ionic or covalent form, e.g., in the form of fluoride. Within the context of this application, a "fluorine-free" product is one that contains no fluorine or only trace amounts of fluorine, regardless of form, i.e., one that contains neither fluorine nor fluoride.

[0019] The oxidizer oxidizes the oxidizable fuel as part of the thermite reaction. In the present invention, CaSO 4 can act as both an oxidizing agent and a sensitizer, but the term "oxidizing agent" as used herein refers to CaSO 4 It will be understood that the term "oxidizer" is used to refer to any oxidizer present in the composition that is not iron oxide (Fe 2 O 3 , FeO and / or Fe 3 O 4 ), Ferrosilite (FeSiO 3 ), manganese dioxide (MnO 2 ), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), sodium chlorate (NaClO 3 ), potassium chlorate (KClO 3 ), strontium sulfate (SrSO 4 ), barium sulfate (BaSO 4 ), titanium dioxide (TiO 2 ), copper oxide (CuO), naturally occurring minerals containing these substances and combinations.

[0020] In some embodiments, the oxidizer comprises a substantially water insoluble oxidizer. A material is considered to be substantially water insoluble if its solubility in water is less than 0.5 g / 100 ml at 20° C. The use of an insoluble oxidizer is advantageous in that the refractory article can be prepared from the composition using an aqueous slurry of the solid components and is suitable for manufacture by the core shot process. Substantially water insoluble oxidizers include iron oxide, manganese dioxide, copper oxide, strontium sulfate, barium sulfate, and titanium dioxide.

[0021] In some embodiments, the oxidizing agent is iron oxide (Fe 2 O 4 and / or Fe 3 O 4 ), Ferrosilite (FeSiO 3 ), potassium nitrate (KNO 3 ), manganese dioxide (MnO 2 ), titanium dioxide (TiO 2 In some embodiments, the oxidizer comprises one or more oxidizers selected from the group consisting of iron oxide (Fe 2 O 4 and / or Fe 3 O 4 ), Ferrosilite (FeSiO 3 ) and potassium nitrate (KNO 3 ) combination.

[0022] In some embodiments, the composition comprises at least 2%, at least 5%, at least 10%, at least 12%, at least 15%, at least 20%, or at least 25% by weight of the oxidizing agent. In some embodiments, the composition comprises no more than 30%, no more than 25%, no more than 20%, no more than 15%, no more than 12%, or no more than 10% by weight of the oxidizing agent. In some embodiments, the composition comprises between 2-30%, between 5-25%, or between 10-20% by weight of the oxidizing agent.

[0023] In some embodiments, the oxidizing fuel comprises a metal. In some embodiments, the metal is selected from one or more of aluminum, magnesium, silicon, tin, zinc, and alloys thereof, either alone or in mixture. In some embodiments, the oxidizing fuel comprises aluminum and metallic silicon. A combination of different oxidizing metals with different reactivities can help tailor the properties of thermite reactions (e.g., ignition time, burn time, maximum temperature, etc.). For example, without wishing to be bound by theory, the inventors of the present invention have found that using a combination of metallic silicon and aluminum as the oxidizing fuel can help balance the properties of thermite reactions in the absence of a fluoride sensitizer, since silicon has a higher activation energy than aluminum and also has a higher energy output.

[0024] The oxidizing fuel may be in the form of particulate material (e.g., fine powder, coarse powder, grindings, or combinations thereof), foil, skimmings, dross, or combinations thereof. In some embodiments, the oxidizing fuel comprises a combination of metal foil and particulate metal. In some embodiments, the oxidizing fuel comprises metal in the form of an atomized powder, i.e., in a very fine powder form. Oxidizing fuel in atomized powder form may be more reactive than other forms of oxidizing fuel. Combinations of different forms of oxidizing fuel can be used to tune the properties of the thermite reaction and also balance these properties in the absence of a fluoride sensitizer.

[0025] In some embodiments, the oxidizing fuel comprises an atomized powder, the atomized powder comprising atomized aluminum, atomized silicon, or a combination thereof. In some embodiments, the atomized powder comprises at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, or at least 95% by weight of atomized aluminum. In some embodiments, the atomized powder comprises at least 2% by weight, at least 5% by weight, at least 10% by weight, at least 20% by weight, at least 30% by weight, or at least 40% by weight of atomized silicon. In some embodiments, the atomized powder comprises 60-95% by weight of atomized aluminum and 5-40% by weight of atomized silicon.

[0026] The atomized aluminum powder may have a D90 particle size of less than 150 μm, less than 140 μm, less than 130 μm, less than 120 μm, less than 110 μm, or less than 100 μm, a D50 particle size of less than 80 μm, less than 70 μm, less than 60 μm, less than 50 μm, or less than 40 μm, and / or a D10 particle size of less than 30 μm, less than 25 μm, less than 20 μm, less than 15 μm, or less than 10 μm. In some embodiments, the oxidizing fuel comprises atomized aluminum powder having a D90 particle size of less than 130 μm, a D50 particle size of less than 60 μm, and a D10 particle size of less than 20 μm.

[0027] The atomized silicon powder may have a D90 particle size of less than 65 μm, less than 55 μm, less than 45 μm, less than 35 μm, or less than 25 μm. In some embodiments, the oxidizing fuel comprises atomized silicon having a D90 particle size of less than 45 μm.

[0028] In some embodiments, the oxidizing fuel includes atomized aluminum having a D90 particle size of less than 130 μm and atomized silicon having a D90 particle size of less than 45 μm.

[0029] In some embodiments, the oxidizing fuel comprises at least 20% by weight, at least 30% by weight, at least 40% by weight, at least 50% by weight, at least 60% by weight, or at least 70% by weight of the atomized powder. In some embodiments, the oxidizing fuel comprises no more than 80% by weight, no more than 70% by weight, no more than 60% by weight, no more than 50% by weight, or no more than 40% by weight of the atomized powder. In some embodiments, the oxidizing fuel comprises 20-80% by weight, 30-70% by weight, or 40-60% by weight of the atomized powder. The exact percentage of atomized powder in the oxidizing fuel may depend on the type and percentage of the various metals used. For example, if a low percentage of silicon or no silicon is used, a higher percentage of atomized aluminum may be required.

[0030] In some embodiments, the composition comprises at least 5%, at least 10%, at least 15%, at least 20%, or at least 25% by weight of oxidizing fuel. In some embodiments, the composition comprises no more than 30%, no more than 25%, no more than 20%, no more than 15%, or no more than 10% by weight of oxidizing fuel. In some embodiments, the composition comprises between 5-30%, between 10-25%, or between 15-25% by weight of oxidizing fuel.

[0031] The composition includes a particulate refractory material that acts as a filler and provides insulating properties. The particulate refractory material may be in the form of a powder, granules, fibers, or any combination thereof. In some embodiments, the particulate refractory material is selected from silica, olivine, alumina, aluminosilicates (including chamotte), pumice, magnesia, chromite, zircon, and combinations thereof.

[0032] Preferably, the composition comprises at least 30%, at least 35%, at least 40%, at least 45%, or at least 50% by weight of particulate refractory material. In some embodiments, the composition comprises no more than 70%, no more than 65%, no more than 60%, no more than 55%, or no more than 50% by weight of particulate refractory material.

[0033] Additionally or alternatively, the particulate refractory material has a density of 1 g / cm 3 Less than or equal to 0.5g / cm 3 Lightweight materials include those having a density less than 1000 nm. Such lightweight materials are particularly useful for providing thermal insulation. Suitable lightweight materials include perlite, diatomaceous earth, burnt rice husks (rice husk ash), refractory fibers, fly ash floaters (hollow microspheres), cenospheres, other natural or synthetic hollow spheres such as alumina, aluminous silica or aluminosilicates, and combinations thereof.

[0034] Binders suitable for use in the present invention include resins (e.g., phenol formaldehyde resins or urea formaldehyde resins), gums (e.g., gum arabic or xanthan gum), sulfite lye, starch, acrylic dispersions, colloidal silica, colloidal alumina, and combinations thereof. In some embodiments, the binder comprises a combination of a resin and a starch. In some embodiments, the binder may comprise two or more starches. In some embodiments, the one or more starches may include wheat starch, potato starch, corn starch, waxy maize starch, rice starch, soybean starch, tapioca starch, modified starches, cationic starches, heat swelling starches, and combinations thereof. In some embodiments, the one or more starches may be partially or fully pre-gelatinized. In one series of embodiments, the one or more starches include a combination of non-pregelatinized and pregelatinized starches, both preferably wheat starches.

[0035] In a preferred set of embodiments, the binder is non-toxic and / or biodegradable. Starch is particularly preferred, as it decomposes easily and does not contaminate the foundry sand after use. Starch can, for example, simply be washed off during regeneration of the foundry sand, without requiring any specialist water treatment thereafter.

[0036] In some embodiments, the composition includes 0.5-5% by weight, or 1-4% by weight, or 1.5-3.5% by weight, or 2-3% by weight of a binder.

[0037] In some embodiments, the composition further comprises a carrier fluid, such as water. Preferably, the composition comprises a carrier fluid in which the other components of the composition are not dissolved, such that a slurry of suspended solid components is produced for producing the fire resistant article.

[0038] In a second aspect of the present invention, there is provided a refractory article for use in a feeding system in metal casting, the refractory article being formed from a composition as described herein.

[0039] The fire-resistant article can be manufactured by a variety of methods, including the slurry method (vacuum forming) or the core shooting method (blowing or ramming). The choice of binder may depend on the method by which the fire-resistant article is manufactured.

[0040] In some embodiments, the refractory article is an exothermic refractory article. Refractory articles may include many of the products used in foundries to assist in the delivery of feeders to metal castings, such as feeder sleeves (also known simply as "feeders" or "sleeves") and other shaped articles that cover parts of a casting or mould assembly (e.g. feeder boards, profile cores, exothermic padding and sleeve and core combinations).

[0041] In some embodiments, the refractory article is a feeder sleeve. The shape of the feeder sleeve is not particularly limited. The feeder sleeve may have a circular or elliptical cross-section, may have parallel or sloping sides and may be openable or closable. In embodiments where the feeder sleeve is closed, it may have a domed or flat cover. The feeder sleeve may be cylindrical (i.e. with a circular cross-section and parallel sides) or frusto-conical (i.e. with a circular cross-section and sloping sides).

[0042] In some embodiments, the fire resistant article is a feeder board, which may be in the form of a bonded mat. The bonded mat is wrapped around a feeder pattern or deployed in a conventional feeder sleeve. Alternatively, the feeder board can be used as a feeder cap that is placed over an open sleeve, the shape of the board being dictated by the shape of the feeder sleeve. Typically, the feeder cap has a circular or elliptical cross-section.

[0043] In some embodiments, the refractory article is a Williams core (also known as a Williams wedge). A Williams core is an article with a sharply pointed edge, typically conical or wedge shaped, that is placed at the top of the closure sleeve to improve and stabilise the feeder effect. The Williams core may be integrally formed with the feeder sleeve or may be manufactured separately and then fixed to the inside of the sleeve.

[0044] In some embodiments, the refractory article may include a combination of a sleeve component and a breaker core component that contacts a casting surface, the casting surface having a profile shape specifically designed to match the shape of the desired casting.

[0045] In some embodiments, the refractory article may include a profiled shape known as a pad, which utilizes the exothermic properties of the pad to increase the feeding distance of the sleeve and to slow or control the solidification time of the casting below the pad. In one embodiment, the pad is used in combination with a sleeve component to form a single unit.

[0046] It will be understood that any of the optional features and embodiments described in relation to the first aspect may equally apply to the composition of the second aspect.

[0047] <Experimental Procedure> Standard cylindrical specimens were produced using the Georg Fischer (+GF+) process. Green (uncured) feeder sleeves were first produced using a slurry process. The green feeder sleeves were then chopped into pieces and mixed using a flat blade paddle mixer until the components were thoroughly mixed and the composition was homogenous. A sample of the mixture was loosely packed inside a cylindrical precision specimen (50mm inner diameter) and placed on a +GF+ sand rammer (type SPRA) which compressed the mixture with three ramming movements. After ensuring that the height was within the tolerance marks, the specimen was removed using an ejector (stripping post). The specimens were then placed in a drying oven at 160°C for 90 minutes to cure. The resulting cylindrical specimens had dimensions of 50mmx50mm.

[0048] The overall composition of the test specimen (on a solids basis) was as follows: Calcium sulfate: 0.5 to 5% by weight Fluorine-based sensitizer: 0-2% by weight Iron oxide (Fe 3 O 4 ) Oxidizing agent: 7 to 10% by weight Oxidizer containing potassium nitrate and ferrosilite: 10-20% by weight Aluminum: 10-20% by weight Silicon: 1 to 5% by weight Binder: 0.5-5% by weight High density refractory filler: 40-60% by weight Low density refractory filler: 0-5% by weight

[0049] The aluminum includes a mixture of aluminum foil, powder and crushed material, the silicon includes atomized silicon powder, the high density refractory fillers include a mixture of sand, chamotte, pumice and aluminosilicate materials, and the low density refractory fillers include cenospheres.

[0050] The proportions of the high density refractory filler and the low density refractory filler were appropriately adjusted so that the balance of all components was 100% by weight in total.

[0051] <Ignition time and burn time> Using an in-house test apparatus (Amitec), standard specimens were preheated and maintained at 1400°C by placing them on an electrically heated silicon carbide (SiC) plate. Ignition time was measured from the time the specimen was placed on the heater until it ignited (in seconds). Once ignited, the specimens were transferred to a sand bed where they were left to burn out. Burn time was measured as the time from ignition to the end of burning (reported in seconds).

[0052] The desired ignition and burn times vary depending on the application. A short ignition time is particularly useful for small feeder sleeves where it is essential to feed the feeder very quickly into the casting. For larger feeder sleeves, where the casting is fed for a longer period of time, a long burn time is useful and ignition time is not as important.

[0053] <Maximum temperature and time above 1150℃> Al 2 O 3 The protective tube was attached to the green standard specimen by pushing it into the exact center of the specimen to a depth of 25 mm. The specimen was then dried and a thermocouple was connected to a plotter inserted into the protective tube. The specimen was ignited and the maximum temperature reached (Tmax) and the time above 1150°C (t>1150°C) were recorded by the plotter.

[0054] In foundry applications, feeder sleeves only serve a useful purpose if the metal in the feeder is maintained as a liquid. The liquidus temperatures of ferrous metals are in the region of 1150°C, so t>1150°C may be a more accurate indicator of feeder sleeve performance than burn time.

[0055] <Example 1> A series of specimens were prepared and tested as described above using compositions containing varying percentages of fluorine-based sensitizer, and the test results are shown in Table 1 below.

[0056] [Table 1]

[0057] The results show that compositions containing calcium sulfate achieve good heat generation performance even at low levels of fluoride sensitizer. Specimens made with low fluoride compositions (E1 and E2) had slightly longer dosing times and lower maximum temperatures than the high fluoride composition (E3), but had significantly longer burn times and times above 1150°C.

[0058] <Example 2> Another series of low fluoride compositions were prepared and evaluated using varying ratios of atomized aluminum powder to coarse aluminum, with the results shown in Table 2 below.

[0059] [Table 2]

[0060] The results show how the reactivity characteristics of low fluoride refractory articles can be tailored by varying the proportion of fine (highly reactive) and coarse (less reactive) aluminum. In general, low fluoride compositions with a higher proportion of atomized aluminum powder exhibit shorter ignition times and longer burn times than those with a lower proportion of atomized aluminum powder.

[0061] <Example 3> Feeder sleeves according to the invention (E9, E10 and E11) were compared with a commercially available exothermic feeder sleeve (C1) made using the following composition:

[0062] [Table 3]

[0063] It can be seen that the feeder sleeves made using compositions E1-E3 have similar feeder performance as the commercially available feeder sleeve C1, but with significantly less fluorine-based sensitizer in the composition. The inventors have further found that the calcium fluoride used is water insoluble, meaning that there are no contamination issues during regeneration of the moulding sand after the metal casting process has been carried out. Combined with the use of biodegradable binders such as starch and xanthan gum, the environmental properties of the example feeder sleeves are greatly improved compared to the commercially available feeder sleeves.

Claims

1. 1. A composition for making a refractory article for use in a feeder system in metal casting, the composition comprising: 40-60% by weight of particulate refractory material; 10 to 25 weight percent of an oxidizing metal fuel; 10 to 30% by weight of an oxidizing agent; Sensitizers, and a binder; 0.5 to 5% by weight of CaSO ４ , and 1.5% by weight or less of fluorine.

2. 10. The composition of claim 1, wherein the composition contains no more than 1.0 wt.% fluorine or no fluorine.

3. The composition of claim 1 , wherein the sensitizer comprises a water-insoluble fluorine compound.

4. The fluorine compound is calcium fluoride (CaF ２ 4. The composition of claim 3, wherein

5. The oxidizing agent is iron oxide (Fe ２ O ４ And / or Fe ３ O ４ ), Ferrosilite (FeSiO ３ ), potassium nitrate (KNO ３ ), manganese dioxide (MnO ２ ), titanium dioxide (TiO ２ 2. The composition of claim 1, comprising one or more oxidizers selected from the group consisting of copper oxide (CuO) and copper oxide (CuO).

6. 10. The composition of claim 1, wherein the oxidizing fuel comprises aluminum, and optionally the oxidizing fuel comprises aluminum foil and / or aluminum particles.

7. The composition of claim 1 , wherein the oxidizing fuel comprises silicon metal.

8. 10. The composition of claim 1, wherein the oxidizing fuel comprises an atomized powder, and optionally the atomized powder comprises atomized aluminum and / or atomized silicon metal.

9. 9. The composition of claim 8, wherein the atomized powder comprises at least 60% by weight of atomized aluminum.

10. 9. The composition of claim 8, wherein the atomized powder comprises at least 10% by weight of atomized silicon metal.

11. The composition of claim 8 , wherein the oxidizing fuel comprises at least 30% by weight of the atomized powder.

12. The composition of claim 1 further comprising a carrier fluid, optionally wherein the carrier fluid is water.

13. The composition of claim 1 , wherein the fire resistant article is an exothermic fire resistant article.

14. 14. A refractory article for use in a feeder system in metal casting, said refractory article being formed from the composition of any one of claims 1 to 13.

15. 15. The fire resistant article of claim 14, wherein the fire resistant article is a feeder sleeve.