Abstract Aluminum oxide fibers of the approximate percent composition by weight: ______________________________________ Al 2 O 3 61-98% preferably 76-96%
SiO 2 1-20% preferably 3-15%
P 2 O 5 0-10% preferably 0-5%
B 2 O 3 0-10% preferably 0-5%
MgO 0-5% preferably 0-1%
C 0.1-4% preferably 0.5-2.8%
______________________________________ The fibers are produced by dry spinning a solution containing a neutral or basic aluminum salt of a monobasic lower carboxylic acid, a hydrolyzed silicic acid ester or organoalkoxysilane and polyethylene oxide having a degree of polymerization of at least about 2,000. The product is then heat treated at a temperature between about 400° and 1,800°C. Phosphorus, boron and magnesium may also be present in the solution and end up in the fiber as oxides.
An aluminum oxide fiber of about the following percent composition by weight: ______________________________________
Al.sub.2 O.sub.3
61-98
SiO.sub.2 1-20
P.sub.2 O.sub.5
0-10
B.sub.2 O.sub.3
0-10
MgO 0-5
C 0.1-4
______________________________________
the carbon being present in amorphous form.
Claim 2
Dependent Claim
36 words
An aluminum oxide fiber of about the following percent composition by weight: ______________________________________
Al.sub.2 O.sub.3
61-98
SiO.sub.2 1-20
P.sub.2 O.sub.5
0-10
B.sub.2 O.sub.3
0-10
MgO 0-5
C 0.1-4
______________________________________
the carbon being present in amorphous form.
Claim 3
Dependent Claim
13 words
An aluminum oxide fiber according to claim 1 which is amorphous to X-rays.
Claim 4
Dependent Claim
17 words
A polycrystalline aluminum oxide fiber according to claim 1 having a γ-Al 2 O 3 X-ray diagram.
Claim 5
Dependent Claim
35 words
A polycrystalline aluminum oxide fiber according to claim 1, having an X-ray diagram which shows a mullite phase and at least one of the phases γ-Al 2 O 3 and δ-Al 2 O 3 .
Claim 6
Dependent Claim
23 words
A polycrystalline aluminum oxide fiber according to claim 1, having an X-ray diagram which shows the phases α-Al 2 O 3 and mullite.
Claim 7
Dependent Claim
60 words
An aluminum oxide fiber according to claim 1, embedded as reinforcement in a plastic, metal, glass or ceramic matrix, the fiber having about the following percent composition by weight: ______________________________________
Al.sub.2 O.sub.3
76-96
SiO.sub.2 3-15
P.sub.2 O.sub.5
0-5
B.sub.2 O.sub.3
0-5
MgO 0-1
C 0.5-2.8
______________________________________ the carbon being present in amorphous form and the fiber being irregular in cross-section.