Titanium diboride coatings and their interaction with the substrates
An experimental investigation of the chemical vapor deposition (CVD) of titanium diboride (TiB/sub 2/) on metallic substrates, using the hydrogen reduction of TiCl/sub 4/ and BCl/sub 3/ at 1 atmosphere and at temperatures between 850/sup 0/C and 1050/sup 0/C is described. To be coated, the substrate had to meet the following requirements: (1) ability to withstand the deposition temperature without detrimental transformation, (2) chemical inertness to the by-products of the reaction (mostly HCl), (3) reasonable matching of its thermal expansion with that of TiB/sub 2/. The latter requirement may be partially circumvented by using a ductile intermediate coating such as Cu or Ni. Substrates meeting these requirements were W, Ta, Ni, WC, TiC, Kovar and some high chrome steels. Coatings on these substrates were examined by metallographic techniques, scanning electron microscope, x-ray diffraction and electron microprobe. The structures and the degree of interdiffusion were determined. In most cases, intermediate borides of the type M/sub 3/B and M/sub 2/B were formed. The hardness of the coatings was 3330 +- 310 kg/mm/sup 2/ (VHN/sub 50/). Coatings of TiB/sub 2/ have already been used successfully on letdown valves in a bench scale coal liquefaction reactor at Sandia Laboratories.
- Research Organization:
- Sandia Labs., Albuquerque, N.Mex. (USA)
- DOE Contract Number:
- EY-76-C-04-0789
- OSTI ID:
- 6789286
- Report Number(s):
- SAND-78-0555C; CONF-780430-3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ALLOYS
BORIDES
BORON COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
CHROMIUM ALLOYS
CHROMIUM STEELS
COATINGS
COBALT ALLOYS
DEPOSITION
ELEMENTS
IRON ALLOYS
IRON BASE ALLOYS
KOVAR
MANGANESE ADDITIONS
MANGANESE ALLOYS
METALLOGRAPHY
METALS
NICKEL
NICKEL ALLOYS
PROTECTIVE COATINGS
REFRACTORY METALS
STEELS
SURFACE COATING
TANTALUM
TITANIUM BORIDES
TITANIUM CARBIDES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN
TUNGSTEN CARBIDES
TUNGSTEN COMPOUNDS
VERY HIGH TEMPERATURE