Method of producing a tungsten heavy alloy product

Details Method of producing a tungsten heavy alloy product Method of producing a tungsten heavy alloy product

1992-08-20

1994-08-30

Walsh, Donald P.

Powder metallurgy processes

Powder metallurgy processes with heating or sintering

Consolidation of powder prior to sintering

419 8, 419 23, 419 28, 419 29, 419 32, 419 36, 419 47, 419 54, 419 57, 419 58, 419 60, 428548, B22F 316

Patent

active

053425731

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a method of producing a tungsten heavy alloy product having a complex configuration and high strength by mixing material powder of a tungsten heavy alloy with an organic binder, injection molding the mixture into a molded material, then sintering the molded material.


BACKGROUND ART

A tungsten heavy alloy is composed of about 80% or more by weight of tungsten, and iron or copper, and especially where its tungsten content is more than about 90% by weight, the tungsten heavy alloy is called a tungsten superheavy alloy. Such a tungsten heavy alloy is becoming increasingly used in applications utilizing thermal expansion, such as thermal stress buffering for ceramic and metal materials, and applications requiring high mechanical strength, such as quills, shanks, and boring bars, as well as in such applications as automobile flyweights, spray nozzle weights, computer HDD weights, and VTR heads, which require a large weight though small in size.
Tungsten heavy alloys, including such tungsten superheavy alloys, have hitherto been produced by powder metallurgical techniques, because they contain a high melting-point tungsten. That is, W powder, Ni powder, and Fe powder or Cu powder are mixed in predetermined proportions, and the mixture powder is molded by a conventional press molding technique, such as pressing or CIP molding, the molded material being then sintered into a hard mass having a nearly perfect compact density. A similar powder metallurgical method is widely known for producing iron-base alloys.
However, such conventional powder metallurgical methods as mentioned above, wherein a molded material is obtained by press molding, have a disadvantage that the product to be produced is limited in configuration and dimensional accuracy. For example, press molding can produce no more than products of such a configuration as to permit the product to be monoaxially molded. CIP molding cannot provide high molding accuracy because molding is effected in a rubber mold, although it can produce a product of a tridimensional configuration. As such, in order to obtain the desired configuration for a final product, it is necessary to machine the product with respect to almost all portions thereof after the product has been sintered, which naturally means low productivity and increased costs.
When producing a composite product comprising a tungsten heavy alloy and an iron-base alloy or other metal material, it has been usual practice to join by silver brazing the alloy portions made to respective predetermined shapes by conventional powder metallurgical techniques, or to cast the tungsten heavy alloy portion, produced by a conventional powder metallurgical technique, in chills with an iron-base alloy or other metal material.
However, such a method does not provide a dependable junction or sufficient strength, and this constitutes a great limitation upon using the resulting product as a structural material.
In view of such disadvantages of the foregoing powder metallurgical methods, there have been developed methods as disclosed in Japanese Patent Publication No. 63-42682 and Japanese Patent Application Laid-Open Publication No. 62-250102, wherein metal or alloy powder is mixed with an organic binder and the mixture is injection-molded into a molded material which, in turn, is subjected to thermal decomposition in a non-oxidizing atmosphere or a similar debinding treatment for removal of the organic binder, the resulting product being then sintered.
Also, there has been known a method, as described in Japanese Patent Application Laid-Open Publication No. 62-249712, wherein a mixture of an organic binder and a material powder mass is injection-molded into a molded material which, in turn, is placed in a separate mold having a sufficient cavity, and wherein a mixture of same or different kind of material powder and an organic binder is injected into the cavity for being molded integrally with the previously molded material, the integral moldings being subjected to the step

REFERENCES:
patent: 4801330 (1989-01-01), Bose et al.
patent: 4986961 (1991-01-01), Spencer et al.
patent: 4988386 (1991-01-01), Denning et al.
patent: 5188793 (1993-02-01), Nishio
patent: 5201213 (1991-06-01), Nishio et al.

Affiliated with

Also associated with

Rating

Method of producing a tungsten heavy alloy product does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method of producing a tungsten heavy alloy product, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing a tungsten heavy alloy product will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-28169