Erosion behavior of CVD TiB/sub 2/ coatings on TiB/sub 2/-based ceramic substrates in high-velocity coal-oil slurries
The erosion behavior of chemically vapor deposited (CVD) TiB/sub 2/ coatings deposited on hot pressed TiB/sub 2/ ceramic substrates was studied by impingement of a liquid stream containing 8 wt % of coal derived solids (SRC-1/sup a/) in anthracene oil upon the CVD surface, and compared with erosion of a high-density uncoated TiB/sub 2/ ceramic specimen. Erosive exposure of all specimens was conducted at approx. 350/sup 0/C for 1 h at a liquid flow velocity of 100 m/s and an incidence angle of 20/sup 0/ between the liquid jet and the specimen surfaces. These conditions simulate those present in pressure let-down valves in direct coal liquefaction processes. The principal materials variables included the microstructure and composition of the TiB/sub 2/ ceramic substrates, while the CVD coatings were all deposited under identical conditions at 900/sup 0/C from the hydrogen reduction of TiCl/sub 4/ and BCl/sub 3/. The deposited CVD coatings, which were approx. 50 ..mu..m in thickness, exhibited strong preferred orientation as determined by x-ray diffraction. Relative erosion resistance was assessed by determining the maximum depth of the erosion crater formed in the TiB/sub 2/ surface at the point of jet impingement. For the four CVD coatings exposed, the maximum crater depth values were 0, 1.5, 5.5, and 5.5 ..mu..m, while the uncoated specimen had a depth of approx. 22 ..mu..m. Prior work had shown that only consolidated or single-crystal diamond provided zero crater depths under these conditions. The outstanding erosion resistance of the CVD coatings was apparently related to their crystallographic texture.
- Research Organization:
- Oak Ridge National Lab., TN (USA); Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 7061319
- Report Number(s):
- SAND-82-1152C; CONF-821109-1; ON: DE82018300
- Resource Relation:
- Conference: International conference on recent developments in specialty steels and hard materials, Pretoria, South Africa, 8 Nov 1982; Other Information: Portions of document are illegible
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
01 COAL, LIGNITE, AND PEAT
COAL LIQUEFACTION PLANTS
MATERIALS TESTING
TITANIUM BORIDES
EROSION
CERAMICS
CHEMICAL VAPOR DEPOSITION
COAL
FUEL SLURRIES
PROTECTIVE COATINGS
BORIDES
BORON COMPOUNDS
CARBONACEOUS MATERIALS
CHEMICAL COATING
COATINGS
DEPOSITION
DISPERSIONS
ENERGY SOURCES
FOSSIL FUELS
FUELS
INDUSTRIAL PLANTS
MATERIALS
MIXTURES
SLURRIES
SURFACE COATING
SUSPENSIONS
TESTING
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360205* - Ceramics
Cermets
& Refractories- Corrosion & Erosion
010405 - Coal
Lignite
& Peat- Hydrogenation & Liquefaction