Difference between revisions of "Thermite"
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| − | '''Thermite''' is an energetic composition consisting of a metal powder and metal [[oxide]]. Thermites are a special type of [[Single | + | '''Thermite''' is an energetic composition consisting of a metal powder and metal [[oxide]]. Thermites are a special type of [[Single replacement reaction|single replacment reactions]] that do not take place in aqueous solution. They are capable of producing extreme heat, enough to melt or boil other metals. The products of this reaction are the oxide of the metal powder, and pure metal produced from the oxide. |
== Preparation == | == Preparation == | ||
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The metal powder and metal oxide powder are mixed thoroughly, and most compositions can even be mixed in a blender, as the mixture is very stable. | The metal powder and metal oxide powder are mixed thoroughly, and most compositions can even be mixed in a blender, as the mixture is very stable. | ||
| + | |||
| + | A crude but very effective and simple way to mix the two powders is to add them in a ziplock bag, close the bag and shake the bag until they're evenly mixed. | ||
== Specific compositions == | == Specific compositions == | ||
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This composition usually uses an approximately 8:3 ratio Fe<sub>2</sub>O<sub>3 </sub> to Al by weight. | This composition usually uses an approximately 8:3 ratio Fe<sub>2</sub>O<sub>3 </sub> to Al by weight. | ||
| + | |||
| + | === [[Aluminium]]-[[iron(II,III) oxide]] === | ||
| + | Similar to the Al-Fe<sub>2</sub>O<sub>3</sub>, this form of thermite is almost as energetic, though it produces a bit more iron metal per weight. | ||
| + | |||
=== Aluminium-[[copper(II) oxide]] === | === Aluminium-[[copper(II) oxide]] === | ||
This composition usually uses an approximately 4.4:1 ratio of copper(II) oxide to aluminum powder. This is one of the most energetic thermites commonly used, and shows properties similar to a high explosive if the materials are milled finely enough. | This composition usually uses an approximately 4.4:1 ratio of copper(II) oxide to aluminum powder. This is one of the most energetic thermites commonly used, and shows properties similar to a high explosive if the materials are milled finely enough. | ||
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=== Aluminium-[[manganese dioxide]] === | === Aluminium-[[manganese dioxide]] === | ||
This composition uses approximately 2.42:1 MnO2 to Al. However, this is not a good mixture for recovery of manganese metal due to the metal itself boiling at the reaction temperature - this can be somewhat rectified by adding in [[calcium fluoride]] as a heat sink. | This composition uses approximately 2.42:1 MnO2 to Al. However, this is not a good mixture for recovery of manganese metal due to the metal itself boiling at the reaction temperature - this can be somewhat rectified by adding in [[calcium fluoride]] as a heat sink. | ||
| + | |||
===Aluminium-[[manganese(II,III) oxide]]=== | ===Aluminium-[[manganese(II,III) oxide]]=== | ||
This is the preferred method of extracting manganese metal from its oxide, as manganese(II,III) oxide is less oxidizing. | This is the preferred method of extracting manganese metal from its oxide, as manganese(II,III) oxide is less oxidizing. | ||
=== Aluminium-[[silicon dioxide]] === | === Aluminium-[[silicon dioxide]] === | ||
| − | This composition uses fine-grade aluminum powder and a source of silica, often sand, and produces pearls or lumps of elemental silicon, making it useful for element collectors. It is not energetic enough on its own to create a self sustaining reaction, so a common formula for this thermite includes extra aluminum powder and [[sulfur]], often in the overall ratio 9:12:10 SiO2:S:Al. Because [[ | + | This composition uses fine-grade aluminum powder and a source of silica, often sand, and produces pearls or lumps of elemental silicon, making it useful for element collectors. It is not energetic enough on its own to create a self sustaining reaction, so a common formula for this thermite includes extra aluminum powder and [[sulfur]], often in the overall ratio 9:12:10 SiO2:S:Al. Because [[aluminium sulfide]] is produced, the slag reacts with water or acid to form [[hydrogen sulfide]], which is highly toxic and can attract unwanted legal attention, sulfur can instead be replaced with an oxidizer such as [[sodium nitrate]] or [[potassium chlorate]], which will both sustain and speed up the thermite reaction. |
| − | === Aluminium- [[bismuth | + | ===Aluminium-[[sulfur]]=== |
| + | This reaction produces aluminium sulfide, which in contact with water releases hydrogen sulfide. | ||
| + | |||
| + | === Aluminium-[[bismuth trioxide]] === | ||
Due to the very low reactivity of [[bismuth]] as a metal, as well as its high density, a very energetic thermite is produced. Properly mixed, this thermite can act as a [[high explosive]] and produces a very loud retort. | Due to the very low reactivity of [[bismuth]] as a metal, as well as its high density, a very energetic thermite is produced. Properly mixed, this thermite can act as a [[high explosive]] and produces a very loud retort. | ||
| + | |||
===Aluminium-[[titanium dioxide]]-[[calcium sulfate]]=== | ===Aluminium-[[titanium dioxide]]-[[calcium sulfate]]=== | ||
| + | |||
===Aluminium-[[vanadium pentoxide]]=== | ===Aluminium-[[vanadium pentoxide]]=== | ||
This composition is highly explosive. | This composition is highly explosive. | ||
=== [[Calcium]]-[[neodymium fluoride]] === | === [[Calcium]]-[[neodymium fluoride]] === | ||
| − | Calcium metal reacted with neodymium fluoride has been proposed as a method to reduce the neodymium metal extracted from [[ | + | Calcium metal reacted with neodymium fluoride has been proposed as a method to reduce the neodymium metal extracted from [[neodymium iron boron magnet]]s. |
=== [[Lithium]]-neodymium fluoride === | === [[Lithium]]-neodymium fluoride === | ||
| − | Lithium metal reacted with neodymium fluoride has been proposed as a method to reduce the neodymium metal extracted from [[ | + | Lithium metal reacted with neodymium fluoride has been proposed as a method to reduce the neodymium metal extracted from [[neodymium iron boron magnet]]s. |
| − | ===[[Magnesium]]-[[ | + | |
| + | ===[[Magnesium]]-[[boron trioxide]]=== | ||
This composition can be used to isolate elemental boron. Care must be taken to cover the reaction after it begins to prevent re-oxidation of the boron. Afterwards, hydrochloric acid is used to dissolve the impurities, leaving boron undissolved. Some boron is reduced to magnesium boride in the reaction. | This composition can be used to isolate elemental boron. Care must be taken to cover the reaction after it begins to prevent re-oxidation of the boron. Afterwards, hydrochloric acid is used to dissolve the impurities, leaving boron undissolved. Some boron is reduced to magnesium boride in the reaction. | ||
| + | |||
===Magnesium-[[silicon dioxide]]=== | ===Magnesium-[[silicon dioxide]]=== | ||
| + | This reaction will also to produce [[magnesium silicide]], especially if there's an excess of magnesium. | ||
| + | |||
| + | ==References== | ||
| + | <references/> | ||
| + | ===Relevant Sciencemadness threards=== | ||
| + | *[http://www.sciencemadness.org/talk/viewthread.php?tid=10249 Exotic thermites & analogs] | ||
| + | *[http://www.sciencemadness.org/talk/viewthread.php?tid=26094 Questions about thermite] | ||
| + | |||
| + | [[Category:Pyrotechnics]] | ||
| + | [[Category:Energetic mixtures]] | ||
Latest revision as of 18:56, 2 January 2023
Thermite is an energetic composition consisting of a metal powder and metal oxide. Thermites are a special type of single replacment reactions that do not take place in aqueous solution. They are capable of producing extreme heat, enough to melt or boil other metals. The products of this reaction are the oxide of the metal powder, and pure metal produced from the oxide.
Contents
- 1 Preparation
- 2 Specific compositions
- 2.1 Aluminium-iron(III) oxide
- 2.2 Aluminium-iron(II,III) oxide
- 2.3 Aluminium-copper(II) oxide
- 2.4 Aluminium-manganese dioxide
- 2.5 Aluminium-manganese(II,III) oxide
- 2.6 Aluminium-silicon dioxide
- 2.7 Aluminium-sulfur
- 2.8 Aluminium-bismuth trioxide
- 2.9 Aluminium-titanium dioxide-calcium sulfate
- 2.10 Aluminium-vanadium pentoxide
- 2.11 Calcium-neodymium fluoride
- 2.12 Lithium-neodymium fluoride
- 2.13 Magnesium-boron trioxide
- 2.14 Magnesium-silicon dioxide
- 3 References
Preparation
A sufficiently reactive metallic reducer and metal oxide oxidizer are required for a thermite.
The metal powder and metal oxide powder are mixed thoroughly, and most compositions can even be mixed in a blender, as the mixture is very stable.
A crude but very effective and simple way to mix the two powders is to add them in a ziplock bag, close the bag and shake the bag until they're evenly mixed.
Specific compositions
Aluminium-iron(III) oxide
This is the most commonly used composition. It combines slow burn rate with high temperature (2500 °C) and produces liquid iron, and is therefore used for thermite welding.
This composition usually uses an approximately 8:3 ratio Fe2O3 to Al by weight.
Aluminium-iron(II,III) oxide
Similar to the Al-Fe2O3, this form of thermite is almost as energetic, though it produces a bit more iron metal per weight.
Aluminium-copper(II) oxide
This composition usually uses an approximately 4.4:1 ratio of copper(II) oxide to aluminum powder. This is one of the most energetic thermites commonly used, and shows properties similar to a high explosive if the materials are milled finely enough.
Aluminium-manganese dioxide
This composition uses approximately 2.42:1 MnO2 to Al. However, this is not a good mixture for recovery of manganese metal due to the metal itself boiling at the reaction temperature - this can be somewhat rectified by adding in calcium fluoride as a heat sink.
Aluminium-manganese(II,III) oxide
This is the preferred method of extracting manganese metal from its oxide, as manganese(II,III) oxide is less oxidizing.
Aluminium-silicon dioxide
This composition uses fine-grade aluminum powder and a source of silica, often sand, and produces pearls or lumps of elemental silicon, making it useful for element collectors. It is not energetic enough on its own to create a self sustaining reaction, so a common formula for this thermite includes extra aluminum powder and sulfur, often in the overall ratio 9:12:10 SiO2:S:Al. Because aluminium sulfide is produced, the slag reacts with water or acid to form hydrogen sulfide, which is highly toxic and can attract unwanted legal attention, sulfur can instead be replaced with an oxidizer such as sodium nitrate or potassium chlorate, which will both sustain and speed up the thermite reaction.
Aluminium-sulfur
This reaction produces aluminium sulfide, which in contact with water releases hydrogen sulfide.
Aluminium-bismuth trioxide
Due to the very low reactivity of bismuth as a metal, as well as its high density, a very energetic thermite is produced. Properly mixed, this thermite can act as a high explosive and produces a very loud retort.
Aluminium-titanium dioxide-calcium sulfate
Aluminium-vanadium pentoxide
This composition is highly explosive.
Calcium-neodymium fluoride
Calcium metal reacted with neodymium fluoride has been proposed as a method to reduce the neodymium metal extracted from neodymium iron boron magnets.
Lithium-neodymium fluoride
Lithium metal reacted with neodymium fluoride has been proposed as a method to reduce the neodymium metal extracted from neodymium iron boron magnets.
Magnesium-boron trioxide
This composition can be used to isolate elemental boron. Care must be taken to cover the reaction after it begins to prevent re-oxidation of the boron. Afterwards, hydrochloric acid is used to dissolve the impurities, leaving boron undissolved. Some boron is reduced to magnesium boride in the reaction.
Magnesium-silicon dioxide
This reaction will also to produce magnesium silicide, especially if there's an excess of magnesium.
