High temperature corrosion resistant coatings for gas flare systems

Gas flaring systems are used in processing plants to eliminate excess gases while serving as a safe pressure-relieving system. These systems are built using 310 stainless steel (SS310) thanks to its mechanical properties and performance under high temperature operating conditions. However, the findings have revealed that SS310 is susceptible to high temperature sulfidation when exposed to a corrosive environment. In the present work, SEM analysis has been conducted to investigate the causes of this type of failure. To tackle this problem, high velocity oxygen fuel (HVOF) thermal spraying was used to deposit a double-layer thermal barrier coatings, including a top yttria stabilized zirconia layer (TBC) and a bond coating CoNiCrAlY layer (BC) on SS310 substrates. The performance of the coatings was tested by exposing it to a high temperature corrosive environment. As a result, an improved resistance to corrosion was observed. This improved performance can be attributed to the absence of tetragonal to monoclinic phase change transformation, and to a decrease in the volume fraction of the monoclinic phase in yttria stabilized zirconia top coat, as indicated by XRD analysis.