A first comparison is established between ANOMAG and PE-CVD taking into consideration that the first is an industrial process, while plasma depositions experiments have been performed in a lab-scale reactor. The comparison has been established taking into account only the electricity use required for covering a 1m2 of magnesium parts. As a matter of fact, during the LCA activities it is crucial the precise definition of the functional unit and a correct LCA comparison can be performed only if the functional properties are exactly the same. The obtained results showed the very low environmental impact of PECVD that render the plasma deposition technique very interesting for future industrial applications.
A second comparison has been established between two industrial processes: ANOMAG and KERONITE. In this case the LCA study have been carried out taking into account the global energy requirement linked with the covering of 1 m2 of magnesium parts with a 20 µm protective layer. The results show that KERONITE coating process has a higher impact if compared with ANOMAG, but this result has to be revised taking into account differences in the corrosion protective properties and others environmental impact parameters.
Moreover, due to the high impact of electrolytic magnesium production, the analysis shows that the coating processes have global energetic and environmental loads depending on the shape of magnesium part. The GER weight of the coating process is of the same order of the magnesium production and overcomes this when magnesium castings have a coil type shape. In fact, the global energy requirement shows that the specific surface area of magnesium parts is the most critical parameter in the case of coating industry, because the contribution to GER of the coating has the same weight of the alloy production at shape factor commonly reached in castings.
The comparison between different coating processes is difficult due to the simplification involved if the thickness of the layer is the only considered parameter.