Chemical vapor deposition of erosion resistant TiB/sub 2/ coatings

Conference · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6826197

Caputo, A J; Lackey, W J; Wright, I G

TiB/sub 2/ coatings were chemically vapor deposited by hydrogen reduction of TiCl/sub 4/ and BCl/sub 3/. Process variables investigated were deposition temperatures from 750 to 1050/sup 0/C and the TiCl/sub 4/ and BCl/sub 3/ flow rates. Various grades of commercially available cemented carbides and experimental nickel-bonded TiB/sub 2/ were used as substrates. Resistance of the coatings to erosion was evaluated using a hot, coal-oil slurry impingement test. The TiB/sub 2/ deposition rate was temperature dependent ranging from 0.1 to 2.9 ..mu..m/min between 750 and 950/sup 0/C. The surface morphology of the coatings was nodular with the size of the nodules increasing with temperature. The coatings were dense and adherent. The grain size varied with deposition conditions. TEM showed the grain size to be very small (2 to 300 nm), increasing with distance from the substrate. Electron microscopy and x-ray diffraction indicated only the presence of single-phase TiB/sub 2/ and ion microprobe analysis revealed a constant Ti/B ratio across the coating thickness. Energy dispersive fluorescence analyses showed coatings deposited at 800/sup 0/C contained more chlorine than coatings deposited at the higher temperatures. Coating microhardness and erosion resistance were temperature dependent. The hardness of coatings deposited at 800 and 900/sup 0/C were 15 and 32 GPa, respectively. Coatings deposited at 850/sup 0/C or below experienced extensive erosion (up to 30 ..mu..m deep craters during a 1 h test) while those deposited at 900/sup 0/C and above showed very little or no erosion (0 to 2 ..mu..m).

• Research Organization: Oak Ridge National Lab., TN (USA); Battelle Columbus Labs., OH (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6826197
• Report Number(s): CONF-8405190-1; ON: DE84012351
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360200* -- Ceramics
Cermets
& Refractories
BORIDES
BORON COMPOUNDS
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
COATINGS
CRYSTAL STRUCTURE
DEPOSITION
EROSION
GRAIN SIZE
HARDNESS
MECHANICAL PROPERTIES
MICROHARDNESS
MICROSTRUCTURE
PROTECTIVE COATINGS
SIZE
SURFACE COATING
TITANIUM BORIDES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS