Aluminum nitride flakes and spheres
AssigneeE. I. Du Pont de Nemours and Company
InventorsJohn D. Bolt, Walter Mahler, Frederick N. Tebbe, Robert J. Young, Jr.
Life of this patent
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Abstract
Methods are described for preparing aluminum nitride of controllable morphology for ceramic and heat conduction applications. The methods comprise forming spherical particles or flakes of an intermediate, RA1NH, followed by heating the spheres or flakes of RA1NH at elevated temperatures to produce high purity aluminum nitride of corresponding morphology. Spheres of RA1NH are formed by (i) freezing a suspension of RA1NH in a liquid medium and thawing, by (ii) aging the suspension, or by (iii) dissolving RA1NH in a liquid medium and precipitating it. Flakes are formed by freezing a suspension of RAINH in a liquid medium and removing frozen medium from the frozen suspension.
Claims17
A method for making aluminum nitride comprising:
- (i) reacting R.sub.3 Al and ammonia to produce RAlNH intermediate of irregular shape,
- (ii) converting the irregularly shaped RAlNH to spheres or flakes in a liquid medium, and
- (iii) heating the RAlNH spheres or flakes to form aluminum nitride of corresponding shape;
- wherein R is selected from at least one member of the group C.sub.x H.sub.2x+l, where x is 1 to 20.
A method for making aluminum nitride comprising performing the following reactions in sequence;
- (A) R.sub.3 Al +NH.sub.3 .fwdarw.R.sub.2 AlNH.sub.2 +RH,
- (B) R.sub.2 AlNH.sub.2 .fwdarw.RAlNH +RH, and
- (C) RAlNH .fwdarw.AlN +RH;
- wherein RAlNH and aluminum nitride are substantially in the form of spheres and R is selected from at least one member of the group C.sub.x H.sub.2x+l, where x is 1 to 20.
A method for making aluminum nitride comprising performing the following reactions in sequence:
- (A) R.sub.3 Al +NH.sub.3 .fwdarw.R.sub.2 AlNH.sub.2 +RH,
- (B) R.sub.2 AlNH.sub.2 .fwdarw.RAlNH +RH, and
- (C) RAlNH .fwdarw.AlN +RH;
- wherein RAlNH and aluminum nitride are substantially in the form of flakes and R is selected from at least one member of the group C.sub.x H.sub.2x+1, where X is 1 to 20.
A suspension of spherical particles of RA1NH in a liquid medium wherein R is selected from at least one member of the group C.sub.x H.sub.2x+1, where x is 1-20.
A suspension of flakes of RA1NH in a liquid medium wherein R is selected from at least one member suspension of C.sub.2 H.sub.5 AlNH. The suspension was treated of the group C.sub.x H.sub.2x+1, where x is 1-20.
Dependencies are inferred from the claim text.