Intermetallic-ceramic coatings for metals protection against erosion-corrosion at high temperatures

Conference · Thu Jul 01 04:00:00 EDT 1999

OSTI ID:20002651

Wang, B Q; Verstak, A; Beliaev, A

A series of erosion-corrosion (E-C) tests was carried out on the NiAl-Al{sub 2}O{sub 3} intermetallic-ceramic coatings deposited with high-velocity oxygen-fuel method (HVOF). The tests attempted to simulate the erosion conditions at the heat exchanger tubes in coal-fired boilers. The E-C behavior of these coatings was investigated and compared with other thermal sprayed coatings. It was found that in comparison to other coatings, eroded by the bed ash at 300 C, the HVOF NiAl-40Al{sub 2}0{sub 3} coating exhibited the lowest thickness loss at a 90{degree} impact angle, and was the second best at a 30{degree} impact angle. Eroded by the fly ash under test temperatures 450--600 C, the HVOF NiAl-40Al{sub 2}O{sub 3} coating demonstrated the highest erosion-corrosion resistance at all impact angles of testing. At temperatures below 200 C, the E-C wastage of the HVOF NiAl-40Al{sub 2}O{sub 3} coating had essentially no dependence on temperature. From 200 C to 600 C the coating thickness loss increased and from 600 to 800 C the thickness loss decreased with temperature. The HVOF NiAl-40Al{sub 2}O{sub 3} coating eroded by cracking and chipping brittle mechanism.

• Research Organization: Metalspray International, Richmond, VA (US)
• OSTI ID: 20002651
• Report Number(s): CONF-990401--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ALUMINIUM OXIDES
COMPOSITE MATERIALS
CORROSION
CRACK PROPAGATION
EMBRITTLEMENT
EROSION
HEAT EXCHANGERS
INTERMETALLIC COMPOUNDS
NICKEL ALLOYS
PROTECTIVE COATINGS
TEMPERATURE DEPENDENCE