# When aluminium is ignited in atmosphere, will it form only aluminium oxide or also aluminium nitride?

We know when lithium is burnt in air, it forms lithium nitride and lithium oxide. I am wondering if this applies to aluminium (other metals) also?

• Magnesium also forms the nitride as well as the oxide when burning in air. – Oscar Lanzi Dec 26 '19 at 20:39

According to the paper by Gromov and Vereshchagin [1], it is indeed formed when burning aluminium, but you could have predicted this simply by considering the standard enthalpy of formation of aluminium oxide $$\Delta_\mathrm{f}H^\circ (\ce{Al2O3}) = \pu{−1675.7 kJ/mol}$$ which will be liberated upon ignition and this energy helps in breaking the strong nitrogen-nitrogen triple bond (bond energy is $$\pu{−945 kJ/mol})$$ and finally this would form aluminium nitride, which also produces some energy (standard enthalpy of formation is $$\pu{−318 kJ/mol}),$$ but the combustion here is not a simple one it requires high temperature as mentioned in the paper, I think this is to sublimate $$\ce{Al2O}$$ which will react with nitrogen and give rise to aluminium nitride.

As HYDR0GEN stated, this combustion isn't simple like throwing a match on aluminium sheet, it needs high temperature. According to the work by Trunov et al. [2, p. 38], as the size of aluminium particles decrease the needed temperature for combustion decreases and that's why researchers who wrote the paper used superfine aluminium powder:

Figure 5. Experimentally determined temperatures of aluminum ignition as a function of the used sample size.

### References

1. Gromov, A.; Vereshchagin, V. Study of Aluminum Nitride Formation by Superfine Aluminum Powder Combustion in Air. Journal of the European Ceramic Society 2004, 24 (9), 2879–2884. DOI: 10.1016/j.jeurceramsoc.2003.09.020. (PDF)
2. Trunov, M. A.; Schoenitz, M.; Dreizin, E. L. Ignition of Aluminum Powders Under Different Experimental Conditions. Propellants, Explosives, Pyrotechnics 2005, 30 (1), 36–43. DOI: 10.1002/prep.200400083.
• When citing third-party resources, make sure to provide a complete human-readable reference and not just "this link" to make your post robust against link rot. Also, always cite the original publication, not a reproduced rip-off of a questionable quality where there is typo in the axis name ("Diamter") and illiterate numbers formatting. I took a liberty to replace the illustration with with the one from original paper. – andselisk Dec 27 '19 at 11:48
• @andselisk thanks for help, it's my first answer – mohamed Dec 27 '19 at 11:57

When the aluminum [powder] is ignited, it will cause a reaction between the aluminum and oxygen in the atmosphere. The required temperature for the aluminum oxide to be formed is almost 3000+ °C.

$$\ce{4 Al + 3 O2 -> 2 Al2O3}$$

In addition, aluminum nitride can't be formed when the aluminum powder is ignited in atmosphere, because the aluminum nitride starts to decompose into aluminum and $$\ce{N2}$$ at a high temperature under atmospheric pressure.

• Aluminium needs high temperature to be ignited but that's why the researchers who wrote the paper used ultra fine powder of aluminium to be ignited easily . See this link :researchgate.net/figure/… – mohamed Dec 27 '19 at 9:08