Volatile Products in the Corrosion of Cr, Mo, Ti, and Four Superalloys Exposed to O(2) Containing H(2)O and Gaseous NaCl

Cooled target collection techniques were used to study the formation of volatile products when samples of Cr, Ti, IN-738, 713C, NASA-TRW VIA, and B-1900 were exposed at elevated temperatures to oxidizing environments containing H(2)O(g) and NaCl(g). Samples were heated to 1050 degrees C in 1 atm of slowly flowing oxygen, saturated with water at 21 degrees C and containing about 50 ppm NaCl(g). Volatile products were detected for all materials except B-1900 and Ti. High pressure mass spectrometric sampling was used to directly identify volatile products emanating from samples of Cr and IN-738 subject to the above environments. Mo samples were also studied at 675 degrees C with 4 ppm NaCl(g) added to the O(2) + H(2)O environment. For Cr and IN-738 the volatile species were identified primarily as (NaCl) (1),(2),(3)CrO(3), (NaOH) 1,2CrO(3), Na(2)Cr(2)O(7), and CrO(2)(OH)(2). These same species are deduced to prevail for 713C and NASA-TRW VIA. For Mo, the major species identified were (NaCl) (1),(2) (MoO(3)) , NaOH(MoO(3))(3), (MoO(3)) (8,4, and MoO2 (OH) 2.)