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/sub 2/O(g) and NaCl(g). Samples were heated to 1050/sup 0/C in 1 atm of slowly flowing oxygen, saturated with water at 21/sup 0/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 identify directly volatile products emanating from samples of Cr and IN-738 subject to the above environments. Mo samples were also studied at 675/sup 0/C with 4 ppM NaCl(g) added to the O/sub 2/ + H/sub 2/O environment. For Cr and IN-738 the volatile species were identified primarily as (NaCl)/sub 1/ /sub 2/ /sub 3/CrO/sub 3/, (NaOH)/sub 1/ /sub 2/--CrO/sub 3/, Na/sub 2/Cr/sub 2/O/sub 7/, and CrO/sub 2/(OH)/sub 2/. These same species are deduced to prevail for 713C and NASA-TRW VIA. For Mo, the major species identified were (NaCl)/sub 1/ /sub 2/(MoO/sub 3/)/sub 3/, NaOH(MoO/sub 3/)/sub 3/, (MoO/sub 3/)/sub 3/ /sub 4/, and MoO/sub 2/(OH)/sub 2/. 1 figure, 6 tables.