Development of improved LACV-30 propeller blade coatings for protection against sand and rain erosion and marine environment corrosion
Abstract
An investigation was conducted of candidate systems offering potential erosion and corrsion protection when applied as coatings to Aluminum 7075 alloy propeller blades used to propel air cushioned vehicles operating in severe environments such as offshore and marine beach logistics missions. Blade lifespans are significantly abbreviated by erosion from sand and water impingement. This work focused on special hard anodized and hard nickel electroplated coatings as candidate protective systems with sand/rain erosion testing to evaluate their merits. Results indicated that anodized coatings did not provide suitable erosion protection to Aluminum 7075 in sand/rain environments, even with dry film lubricant supplemental films. Electroplated hard nickel coatings, Vickers hardnesses in the range of 380 to 440, appeared better for combined sand/rain erosion resistance based on comparisons with prior work. Dilute phosphoric anodizing the aluminum substrates led to excellent bonds and improved corrosion resistance when subsequently plated with ductile nickel from a low pH bath, followed by hard nickel electroplate. Electrodeposited sacrificial corrosion coatings degraded the overall coating bond integrity.
- Publication:
-
Final Report
- Pub Date:
- May 1983
- Bibcode:
- 1983tbac.rept.....M
- Keywords:
-
- Corrosion Resistance;
- Erosion;
- Nickel Coatings;
- Nickel Plate;
- Propeller Blades;
- Protective Coatings;
- Adhesion;
- Anodic Coatings;
- Anodizing;
- Electroplating;
- Ground Effect Machines;
- Hardness;
- Nickel Alloys;
- Engineering (General)