Four hundred hours of long-term material testing have been completed. The PFB combustor operated at 1650/sup 0/F utilizing Pittsburgh No. 8 coal (3% sulfur, 0.06% chlorine) and Pfizer dolomite. After 285 hours, visual inspection of corrosion pins in the low velocity test section indicated that unprotected blade and vane alloys, IN-738, IN-939, U-500 and FSX-414 experienced significant corrosion attack at all three metal temperatures, 1500/sup 0/, 1300/sup 0/ and 1100/sup 0/F. Precious metal aluminide coatings showed good resistance to corrosion at 1500/sup 0/ and 1300/sup 0/F, but appeared susceptible to attack at the 1100/sup 0/F metal temperature. CoCrAlY and FeCrAlY overlay coatings were generally resistant to attack at all three temperatures, although some pitting attack was observed on CoNiCrAlY and FeCrAlY cladding at 1300/sup 0/ and 1100/sup 0/F.