Thermally Sprayed Aluminum-Titanium Alloys for Non-Slip Coating in Marine Environments

Titanium has a limited solid solubility in liquid aluminum but in the thermal spray process, where cooling of the sprayed droplets is very fast, the titanium is held in a supersaturated solid solution which results in a very hard coating on the substrate. The hardness of the layer is amplified by the presence of small intermetallic particles. Steel plates, arc-sprayed with an aluminum titanium alloy, have been subjected to corrosion testing, being compared to pure aluminum.  The resistance of the AlTi layer to corrosion in 0.5% and 5% NaCl rivalled that of pure aluminum, especially in a very agressive environment (5%).  The degree of cathodic protection given to the steel substrate was also as good as that of pure aluminum.  The sprayed plates were also tested for wear resistance, with vehicles using a forklift truck and for pedestrians using a robot wearing working boots.  The robot test reached a maximum of 1,000,000 footfalls without signifiicant wear to tha AlTi layer.  The combination of excellent corrosion resistance and superb wear resistance allows is very interesting for anti-slip apllications in marine environments.  The AlTi alloy is sprayed coarsely onto the steel substrate resulting in a high-friction surface which remains high-friction for over a million footfalls. The material has recently been approved for the deck of two new British aircraft carriers but could be used on more routine steel plates like manhole covers.