An Evaluation of the Oxide Layers in Machining Swarfs to Improve Recycling
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32920
An Evaluation of the Oxide Layers in Machining Swarfs to Improve Recycling

Authors: J. Uka, B. McKay, T. Minton, O. Adole, R. Lewis, S. J. Glanvill, L. Anguilano


Effective heat treatment conditions to obtain maximum aluminium swarf recycling are investigated in this work. Aluminium swarf briquettes underwent treatments at different temperatures and cooling times to investigate the improvements obtained in the recovery of aluminium metal. The main issue for the recovery of the metal from swarfs is to overcome the constraints due to the oxide layers present in high concentration in the swarfs since they have a high surface area. Briquettes supplied by Renishaw were heat treated at 650, 700, 750, 800 and 850 ℃ for 1-hour and then cooled at 2.3, 3.5 and 5 ℃/min. The resulting material was analysed using SEM EDX to observe the oxygen diffusion and aluminium coalescence at the boundary between adjacent swarfs. Preliminary results show that, swarf needs to be heat treated at a temperature of 850 ℃ and cooled down slowly at 2.3 ℃/min to have thin and discontinuous alumina layers between the adjacent swarf and consequently allowing aluminium coalescence. This has the potential to save energy and provide maximum financial profit in preparation of swarf briquettes for recycling.

Keywords: Aluminium, swarf, oxide layers, recycle, reuse.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 533


[1] Toyota, "Toyota Resource Efficiency," ed, 2021.
[2] F. Planet, "Foundry planet," ed: Hubco Forgings, 2010.
[3] P. Foundry, "Planet Foundry," ed: Hubco Forgings, 2010.
[4] Uka J, McKay B, Minton T, Lewis R and Anguilano L*, "Methods to Re-Use and Recycle Aluminium," Evolutions in Mechanical Engineering, vol. 3, no. 2, p. 4, 2020.
[5] K. Wang and R. R. Reeber, "The perfect crystal, thermal vacancies and the thermal expansion coefficient of aluminium," Philosophical Magazine A, vol. 80, no. 7, pp. 1629-1643, 2000, doi: 10.1080/01418610008212140.
[6] Y. L. Wu, J. Hong, D. Peterson, J. Zhou, T. S. Cho, and D. N. Ruzic, "Deposition of aluminum oxide by evaporative coating at atmospheric pressure (ECAP)," Surface & Coatings Technology, vol. 237, pp. 369-378, 2013, doi: 10.1016/j.surfcoat.2013.06.043.
[7] M. A. Trunov, M. Schoenitz, and E. L. Dreizin, "Effect of polymorphic phase transformations in alumina layer on ignition of aluminium particles," Combustion Theory and Modelling, vol. 10, no. 4, pp. 603-623, 2006, doi: 10.1080/13647830600578506.
[8] J. M. Campbell, Castings, 2nd ed. (no. Book, Whole). Oxford; Boston; - eBook: Butterworth-Heinemann, 2003.
[9] S. Lamouri et al., "Control of the γ-alumina to α-alumina phase transformation for an optimized alumina densification," Boletín de la Sociedad Española de Cerámica y Vidrio, vol. 56, no. 2, pp. 47-54, 2017/03/01/ 2017, doi:
[10] Nanografi, "Differences between Alpha and Gamma Alumina nanoparticles," in Blografi vol. 2020, ed., 16 Sep 2019.
[11] S. A. Impey, D. J. Stephenson, and J. R. Nicholls, "Mechanism of scale growth on liquid aluminium," Materials Science and Technology, vol. 4, no. 12, pp. 1126-1132, 1988/12/01 1988, doi: 10.1179/mst.1988.4.12.1126.
[12] P. E. Blackburn and E. A. Gulbransen, "Aluminum Reactions with Water Vapor, Dry Oxygen, Moist Oxygen, and Moist Hydrogen between 500° and 625°C," Journal of The Electrochemical Society, vol. 107, no. 12, p. 944, 1960, doi: 10.1149/1.2427576.
[13] L. P. H. Jeurgens, W. G. Sloof, F. D. Tichelaar, and E. J. Mittemeijer, "Composition and chemical state of the ions of aluminium-oxide films formed by thermal oxidation of aluminium," Surface Science, vol. 506, no. 3, pp. 313-332, 2002, doi: 10.1016/S0039-6028(02)01432-2.
[14] G. M. Scamans and E. P. Butler, "In situ observations of crystalline oxide formation during aluminum and aluminum alloy oxidation," Metallurgical Transactions A, vol. 6, no. 11, pp. 2055-2063, 1975/11/01 1975, doi: 10.1007/BF03161831.
[15] M. Drouzy and C. Mascré, "The oxidation of liquid non-ferrous metals in air or oxygen," Metallurgical Reviews, vol. 14, no. 1, pp. 25-46, 1969/01/01 1969, doi: 10.1179/mtlr.1969.14.1.25.
[16] E. M. Hinton, "The oxidation of liquid aluminium and the potential for oxides in grain refinement of aluminium alloys," University of Birmingham - Dissertation, Dissertation/Thesis, 2016. (Online).