Cubic titanium trialuminide thermal spray coatings - A review

The recently discovered Cr-stabilized cubic titanium trialuminides of the f orm (Al,Cr)(3)Ti exhibit excellent oxidation resistance up to 1200 degreesC and have formed the basis for development of a new family of protective co atings. These intermetallic compounds can be fabricated into powders and th ermal spray coatings much the same as traditional metal alloys. Cubic trial uminide coatings have physical properties that are compatible with a variet y of common engineering materials, including alloys based on Ti, TiAl, Fe, Ni, and Al. Typically, the coatings will impart sufficient protection to pe rmit an increase in the service temperature of a substrate alloy by 150 deg reesC, or more. The purpose here is to summarize the development of these n ew thermal spray coatings, including properties and microstructures, as wel l as performance of the coating on various substrates, A brief comparison i s made between the deposition processes used to date, which include low-pre ssure plasma spray (LPPS), air plasma spray (APS), and high-velocity oxy-fu el (HVOF) deposition. Recent successes in modifying the coatings to a compo site form by incorporating a very fine dispersion of nanoscale carbide part icles are also discussed.