Process for producing plasma sprayed carbide-based coatings with minimal decarburization and near theoretical density

Conference · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5593427

Lenling, W J ^[1]; Smith, M F; Henfling, J A ^[2]

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1. Fisher-Barton, Inc., Watertown, WI (USA)
2. Sandia National Labs., Albuquerque, NM (USA)

Plasma spray deposition of carbide/metal hardcoatings is difficult because complex chemical transformations can occur while spraying, especially in the presence of oxygen. A commercial plasma spray torch has been modified to simultaneously inject carbide powder and a metal alloy powder at two different locations in the plasma stream. Composite hardcoatings of tungsten carbide/cobalt with a nickel-base alloy matrix have been produce with this dual-injection spray process and compared to coatings sprayed with a conventional plasma spray process. X-ray diffraction revealed very little change in the carbide phase composition of dual-injection coatings as compared to the original composition of the carbide spray powder. Conversely, the conventionally sprayed coatings showed significant transformation of the WC phase to the less desirable W{sub 2}C phase, and secondary oxy- carbide phases were also clearly evident. Porosity in the dual- injection coatings was consistently less than 2%, as measured by image analysis of polished metallographic samples. Microhardness results for the dual injection coatings also compared very favorably with values for the conventional coatings. Preliminary results from an ongoing abrasive wear study indicate that the dual-injection coatings are more wear resistant than the conventional coatings, but further research is needed. 6 refs., 3 figs., 3 tabs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5593427
• Report Number(s): SAND-90-0845C; CONF-900520--4; ON: DE91012016
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ABRASION
ALLOYS
CARBIDES
CARBON COMPOUNDS
CERMETS
COATINGS
COBALT
COHERENT SCATTERING
COMPOSITE MATERIALS
DEPOSITION
DIFFRACTION
ELEMENTS
HARDNESS
IMAGES
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
METALLOGRAPHY
METALS
MICROHARDNESS
NICKEL ALLOYS
NICKEL BASE ALLOYS
PLASMA ARC SPRAYING
POROSITY
POWDERS
REFRACTORY METAL COMPOUNDS
SCATTERING
SPRAY COATING
SPRAYED COATINGS
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN CARBIDES
TUNGSTEN COMPOUNDS
WEAR
X-RAY DIFFRACTION