Metallurgical characterization of plasma-sprayed tungsten carbide-cobalt coatings

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6952612

Rangaswamy, S

Four commercial WC-Co powders prepared from different manufacturing techniques and having variations in binder metal content (11-20% wt), and WC grain size (1-15 ..mu.. m). Using identical process parameters, these powders were plasma sprayed, and the resulting coatings were characterized for changes in chemistry, phase content, and microstructural parameters. Finally, the coatings were evaluated for resistance to abrasion, sliding wear, particle erosion, and cavitation erosion. It was found that, in all cases, the plasma-spray process resulted in substantial loss of carbon leading to a decrease in the monocarbide content and an increase in subcarbides such as W/sub 2/C, and WC/sub 1-x/. The combined effects of carbon loss and high temperatures in the plasma resulted in the formation of several Co/sub x/ W/sub y/C/sub z/ phases, among which Co/sub 3/W/sub 3/C was predominant. The extent to which such reactions occur was found to depend on several factors including starting chemistry, powder size, initial phase content, and carbide grain size. In general, finer size powders containing coarser WC grains tend to lose more carbon, whereas powders containing W/sub 2/C tend to lose somewhat less carbon. Wear properties of WC-Co coatings depend on porosity, carbon content, mean diameter of carbide grains and mean free path of the matrix phase in the microstructure.

• Research Organization: State Univ. of New York, Stony Brook (USA)
• OSTI ID: 6952612
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CARBIDES
CARBON COMPOUNDS
COATINGS
COBALT
CRYSTAL STRUCTURE
ELEMENTS
GRAIN SIZE
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
PHASE STUDIES
REFRACTORY METAL COMPOUNDS
SIZE
SPRAYED COATINGS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN CARBIDES
TUNGSTEN COMPOUNDS
WEAR