Methods and compositions involving high specific surface area carbides and nitrides
This patent describes a high specific surface area metal carbide of nitride. The metal is molybdenum, tungsten, titanium, chromium, zirconium, niobium, vanadium, tantalum, hafnium, or rhenium. The carbides and nitrides are prepared from the respective metal oxides and resulting in at least a 5-fold increase in surface area over that of the oxide. It is produced by a method which comprises: heating oxide substantially uniformly and continuously at a rate in the range of 0.1{sup 0} to 5{sup 0}C./min for at least 20 minutes in the presence of a reducing environment and a source of carbon or nitrogen from a temperature at least 25{sup 0}C. prior to substantial completion of formation of carbide or nitride, and through a temperature range wherein reduction of the oxide and reaction with carbon or nitrogen of the source occurs to form a carbide or nitride reaction product, respectively, whereby an effluent is formed comprising an unreacted portion of the source and gases resulting from reaction of the source with the oxide. Wherein the heating continues to a final temperature until the reaction is substantially complete as evidenced by the substantial absence of change in the composition of the effluent; lowering the temperature of the reaction product by at least 25{sup 0}C by stopping the heating after reaching the final temperature or after maintaining the final temperature for the lesser of about one hour of about 50 percent of the time of heating; and wherein the carbide or nitride is characterized by a particle of a size in the range of about 1 to 15 nm and having a specific surface area of at least about 40 m/sup 2//g when measured by BET method.
- Assignee:
- Board of Trustees of the Leland Stanford Jr. Univ., Stanford, CA
- Patent Number(s):
- US 4851206
- Application Number:
- PPN: US 7104568A; TRN: 89-031902
- OSTI ID:
- 5307031
- Resource Relation:
- Patent File Date: 5 Oct 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBIDES
SYNTHESIS
NITRIDES
CHEMICAL COMPOSITION
CHROMIUM
HAFNIUM
MOLYBDENUM
NIOBIUM
RHENIUM
SURFACE PROPERTIES
TANTALUM
TITANIUM
TUNGSTEN
VANADIUM
ZIRCONIUM
CARBON COMPOUNDS
ELEMENTS
METALS
NITROGEN COMPOUNDS
PNICTIDES
TRANSITION ELEMENTS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication
360203 - Ceramics
Cermets
& Refractories- Mechanical Properties