Page 54 - PCMI Journal July 2018
P. 54
David Allen | Emeritus Professor | Cranfield University | UK Photochemical Machining of Aerospace Materials
5/31/18
Facts concerning Magnesium
• The 8th most abundant element in the earth’s crust and the 3rd most plentiful element dissolved in seawater
• Available in almost limitless quantities
• Hard, strong and light (ρ = 1.738 kg.dm-3
at room temperature)
• Silvery-white coloured metal melting at
650°C
• Thermal conductivity of 156 Wm-1K-1
• Very reactive but oxidises to form a passive surface layer
• A wide range of alloys exist
Etchants for magnesium
• The most commonly-used etchant for magnesium is dilute
nitric acid.
• The etchant is usually applied by splash-etching and has been used to fabricate a wide range of products including printing plates, embossing dies and stents.
• The deep etching of magnesium at 0.002 in. per minute is achieved by using the Dowetch or Dirats powderless etching process.
Issue 131 July 2018 PCMI Journal 53
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