Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Liquid phase sintering
Patent
1993-01-11
1995-07-25
Walsh, Donald P.
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Liquid phase sintering
419 9, 419 12, 164 91, 501 94, B22F 700, B22D 1900
Patent
active
054359660
DESCRIPTION:
BRIEF SUMMARY
The present application in a U.S. National Stage Application of International Patent Application Serial No. US/91/04950, filed on Jul. 12, 1992, as a continuation-in-part of U.S. patent application Ser. No. 07/551,288filed on Jul. 12, 1990and now abandoned.
1. Technical Field
This invention relates generally to a novel method for removing metal from a formed self-supporting body. A self-supporting body is made by reactively infiltrating a molten parent metal into a bed or mass containing a boron source material and a carbon source material (e.g., boron carbide) and/or a boron source material and a nitrogen source material (e.g., boron nitride) and, optionally, one or more inert fillers. Once the self-supporting body is formed, it is then subjected to appropriate conditions which causes metallic constituent contained in the self-supporting body to be at least partially removed.
2. Background Art
In recent years, there has been an increasing interest in the use of ceramics for structural applications historically served by metals. The impetus for this interest has been the superiority of ceramics with respect to certain properties, such as corrosion resistance, hardness, wear resistance, modulus of elasticity, and refractory capabilities when compared with metals.
However, a major limitation on the use of ceramics for such purposes is the feasibility and cost of producing the desired ceramic structures. For example, the production of ceramic boride bodies by the methods of hot pressing, reaction sintering and reaction hot pressing is well known. In the case of hot pressing, fine powder particles of the desired boride are compacted at high temperatures and pressures. Reaction hot pressing involves, for example, compacting at elevated temperatures and pressures boron or a metal boride with a suitable metal-containing powder. U.S. Pat. No. 3,937,619 to Clougherty describes the preparation of a boride body by hot pressing a mixture of powdered metal with a powdered diboride, and U.S. Pat. No. 4,512,946 to Brun describes hot pressing ceramic powder with boron and a metal hydride to form a boride composite.
However, these hot pressing methods require special handling and expensive special equipment, they are limited as to the size and shape of the ceramic part produced, and they typically involve low process productivities and high manufacturing cost.
A second major limitation on the use of ceramics for structural applications is their general lack of toughness (i.e. damage tolerance or resistance to fracture). This characteristic tends to result in sudden, easily induced, catastrophic failure of ceramics in applications involving even rather moderate tensile stresses. This lack of toughness tends to be particularly common in monolithic ceramic boride bodies.
One approach to overcome this problem has been to attempt to use ceramics in combination with metals, for example, as cermets or metal matrix composites. The objective of this approach is to obtain a combination of the best properties of the ceramic (e.g. hardness and/or stiffness) and the metal (e.g. ductility). U.S. Pat. No. 4,585,618 to Fresnel, et al., discloses a method of producing a cermet whereby a bulk reaction mixture of particulate reactants, which react to produce a sintered self-sustaining ceramic body, is reacted while in contact with a molten metal. The molten metal infiltrates at least a portion of the resulting ceramic body. Exemplary of such a reaction mixture is one containing titanium, aluminum and boron oxide (all in particulate form), which is heated while in contact with a pool of molten aluminum. The reaction mixture reacts to form titanium diboride and alumina as the ceramic phase, which is infiltrated by the molten aluminum. Thus, this method uses the aluminum in the reaction mixture principally as a reducing agent. Further, the external pool of molten aluminum is not being used as a source of precursor metal for a boride forming reaction, but rather it is being utilized as a means to fill the pores in the resulting ceramic structure
REFERENCES:
patent: 3758662 (1973-09-01), Tobin et al.
patent: 3864154 (1975-02-01), Gazza et al.
patent: 4353714 (1982-10-01), Lee et al.
patent: 4471059 (1984-09-01), Yoshino et al.
patent: 4492670 (1985-01-01), Mizrah et al.
patent: 4544524 (1985-10-01), Mizrah et al.
patent: 4585618 (1986-04-01), Fresnel et al.
patent: 4595545 (1986-06-01), Sane
patent: 4596693 (1986-06-01), Ishizuka et al.
patent: 4605440 (1986-08-01), Halverson et al.
patent: 4692418 (1987-09-01), Boecker et al.
patent: 4702770 (1987-10-01), Pyzik et al.
patent: 4713360 (1987-12-01), Newkirk et al.
patent: 4718941 (1988-01-01), Halverson et al.
patent: 4737328 (1988-04-01), Morelock
patent: 4777014 (1988-10-01), Newkirk et al.
patent: 4793965 (1988-12-01), Mosser et al.
patent: 4806508 (1989-02-01), Dwivedi et al.
patent: 4820498 (1989-04-01), Newkirk
patent: 4828008 (1989-05-01), White et al.
patent: 4834938 (1989-05-01), Pyzik et al.
patent: 4865131 (1989-12-01), Newkirk
patent: 4871696 (1989-10-01), Newkirk et al.
patent: 4874596 (1989-10-01), Kuszyk et al.
patent: 4885130 (1989-12-01), Claar et al.
patent: 4891338 (1990-01-01), Gesing et al.
patent: 4915736 (1990-04-01), Claar et al.
patent: 4916113 (1990-04-01), Newkirk et al.
patent: 4940679 (1990-07-01), Claar et al.
patent: 5000044 (1991-04-01), Newkirk
patent: 5000063 (1991-04-01), Claar
patent: 5004714 (1991-04-01), Claar et al.
patent: 5017334 (1991-05-01), Claar et al.
patent: 5063185 (1991-11-01), Dwivedi et al.
patent: 5098870 (1992-03-01), Claar et al.
patent: 5109539 (1991-05-01), Claar et al.
patent: 5143870 (1992-09-01), Claar et al.
patent: 5149678 (1992-09-01), Claar et al.
patent: 5162098 (1992-11-01), Claar et al.
patent: 5180697 (1993-01-01), Claar et al.
patent: 5232040 (1993-08-01), Johnson et al.
patent: 5238883 (1993-08-01), Newkirk et al.
International Search Report for International Patent Application Ser. No. PCT/US91/04950.
Journal of the Ceramic Society of Japan, vol. 97, No. 12, Dec. 1989, Tokyo, Japan, pp. 72-78.
Johnson William B.
Wang James C.
Bluni Scott T.
Lanxide Technology Company, LP
Mortenson Mark G.
Ramberg Jeffrey R.
Walsh Donald P.
LandOfFree
Reduced metal content ceramic composite bodies does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reduced metal content ceramic composite bodies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reduced metal content ceramic composite bodies will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-737981