Plastic and nonmetallic article shaping or treating: processes – Including step of generating heat by friction
Patent
1988-05-19
1994-08-02
Derrington, James
Plastic and nonmetallic article shaping or treating: processes
Including step of generating heat by friction
423290, 501 96, C04B 3558
Patent
active
053343395
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a boron nitride sinter shaped article consisting of boron nitride alone or of boron nitride and at least one other ceramic component or components. It also relates to a process for the production of such a product.
BACKGROUND TECHNIQUE
A powder of boron nitride (hereinafter called simply BN) has very poor sinterability. Therefore it is a common practice that, as a sintering assistant, a minute amount of at least one oxide such as B.sub.2 O.sub.3, CaO, etc., is added to the BN powder and the mixture is hot pressed into a BN sinter. According to this production process in the prior art, not only is it difficult to obtain a BN sinter of high purity, but it is also almost impossible to obtain a body of complex shape further, the production cost is expensive.
The present invention has been worked out in view of such problems, and has it as an object to provide a BN sinter, suitably of complex shape having high purity and a high mechanical strength made by a process which includes atmospheric pressure sintering.
DISCLOSURE OF THE INVENTION
The inventors of the present invention zealously researched the above-described problems, and as a result, have reached the following conclusions: in course of the sintering, is added as the BN powder of the starting material, then a sinter having a high mechanical strength can be obtained through atmospheric pressure sintering without making use of a sintering assistant. the above-described amorphous BN powder or a powder capable of producing amorphous BN. producing amorphous BN in the starting material for a BN component is preferably chosen to be 5 weight % or more.
While a BN sinter having a density of 1.9 gr/cm.sup.3 and a bending strength of 4.about.7 kgf/mm.sup.2 was provided as a hot-pressed boron nitride sinter in the prior art, according to the present invention a BN sinter having a density of 1.2.about.1.9 gr/cm.sup.3 and a bending strength of 3.about.8 kgf/mm.sup.2 can be obtained. As per the common sense in the prior art, in order to increase a strength of a sinter it was an essentially necessary condition to increase its density. However, according to the present invention, it has become possible to increase a strength of a sinter without always necessitating to increase a density.
The present invention involves the following subject matter: characterized in that at least part of the BN component a starting material is an amorphous BN powder, and after the starting material powder has been shaped it is sintered within a reductive nitriding atmosphere. described in item 1 above, characterized in that the amount of the amorphous BN powder in the above-described BN component serving as a starting material is 5 weight % or more of the amount of the aforementioned BN component powder. characterized in that at least part of a BN component a starting material is a powder capable of producing amorphous BN in the course of the sintering step, and after the starting material powder has been shaped it is sintered within a reductive nitriding atmosphere. described in item 3 above, characterized in that the amount of the "powder capable of producing amorphous BN in the course of the sintering step" in the starting material for the BN component is 5 weight % or more of the amount of the BN component powder. material powder in which a part of the BN powder is an amorphous BN powder. amorphous BN in the course of the sintering step, or a powder consisting of the aforementioned powder and a BN powder as a starting material powder, and shaping and sintering the starting material powder.
The characteristic feature of the present invention resides in that at least a part of the BN component serving as the product starting material is an amorphous BN powder or the powder capable of producing amorphous BN in the course of the sintering step, and preferably the amount of the aforementioned powder is 5 weight % or more of the starting material for the BN component. The reason is because in the case of less than 5 weight % the produ
REFERENCES:
patent: 4590034 (1986-05-01), Hirano et al.
patent: 4913887 (1990-04-01), Sato
Partial Translation of JP 62-59573.
Partial Translation of JP 61-117107.
Kurita Suminiko
Nakashima Masazumi
Nakawara Hiroshi
Derrington James
Kabushiki Kaisha Kouransha
LandOfFree
Boron nitride sinter and process for its production does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Boron nitride sinter and process for its production, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Boron nitride sinter and process for its production will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-63613