A series of the Ni-Cr-Al-Ti alloy, varing Ti/Al ratios, have been studied to develop better hot corrosion resistant alloys and to understand the hot corrosion mechanism.
Hot corrosion test was conducted at 927℃ by crucible test method.
The alloy with the highest Ti/Al ratio has been proved to be the most resistant to hot corrosion attack.
It is proposed that the mechanism of beneficial effect of Ti is due to the earlier formation of solid sodium titanates, which inhibit the further reaction between $Na_2O$ and oxides. It has been known that the addition of $TiO_2$ and $Cr_2O_3$ to $Na_2SO_4$ decrease the hot corrosion rate by decreasing the $Na_2O$ activity, but these experimental results showed that these oxides could not always reduce the $Na_2O$ activity.
The effect of the addition of NaCl to $Na_2SO_4$ on hot corrosion behavior was appeared to reduce the incubation time.
