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Tuesday, December 4, 2007 - 3:00 PM
Application of Aluminum Coatings for the Corrosion Protection of Magnesium by Cold Spray
Magnesium alloys are frequently used in the fabrication of aircraft components due to their good mechanical properties and low density. Due to poor corrosion resistance, magnesium alloys require multi-layer hazardous coating systems and frequent repair or replacement. A low-cost environmentally friendly solution is the application of an aluminum barrier coating to the magnesium by the Cold Spray (CS) process, also known variously as Cold Gas Dynamic Spraying (CGDS), High Velocity Particle Consolidation (HVPC), and Supersonic Particle Deposition (SPD). CS is a low temperature coating technology in which small metal particles (1-50 μm) are injected into a high velocity gas stream to form a dense coating upon impact with a substrate.
In the present study, Cold Spray coatings of aluminum alloys (commercially pure Al (99.5%), high purity Al (99.95%), Al 5356, and Al 4047) were applied to ZE41A-T5 magnesium. The coatings were evaluated for corrosion resistance by electrochemical testing to determine pitting potential, ASTM B117 Salt Spray, and ASTM G71 Galvanic corrosion. Coating adhesion was evaluated by ASTM C633. The coatings were demonstrated as effective corrosion barriers to salt water corrosion. HP Al coatings provided the best galvanic compatibility with Mg, showing essentially no galvanic effect. Coatings of CP Al, 5356 Al and 4047 Al resulted in galvanic currents almost 50 times greater.
See more of The 2007 Tri-Service Corrosion Conference (December 3-7, 2007)