Effects of Al Content and Addition of Third Element on Fabrication of Ti-Al Intermetallic Coatings by Heat Treatment of Warm Sprayed Precursors

摘要

Warm Spraying is an atmospheric coating process based on high-velocity impact bonding of powder particles. By decreasing the temperature of combustion gas through mixing nitrogen with the combustion gas, the oxidation of feedstock powder can be significantly controlled compared with conventional thermal spraying. This advantage is particularly important for Ti-based coating materials, which rapidly oxidize in elevated temperatures. In this study, six Ti-Al composite coatings were fabricated by the Warm Spray process using a mixture of titanium and aluminum powders as a feedstock and applying a two-stage heat treatment at 600 and 1000℃ to obtain intermetallic phases. The microstructure, chemical and phase composition of the deposited and heat-treated coatings were investigated using SEM, EDS and XRD. It was found that the Al content can affect on the thickness expansion of heat treated Ti-Al coatings significantly and can also have a major influence on the porosity development which is caused by Kirkendall effect. The effect of third element addition and heat treatment to produce dense Ti-Al intermetallic coating were also examined.