Solid anti-friction devices – materials therefor – lubricant or se – Solid anti-friction device – article or material therefor – Halogen compound
Reexamination Certificate
2000-02-01
2001-05-08
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Solid anti-friction device, article or material therefor
Halogen compound
C508S109000, C508S112000, C508S129000
Reexamination Certificate
active
06228814
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a carbonaceous composite material excellent in abrasion resistance and self-lubricating properties and having secondary corrosion inhibiting properties and to a sliding member using the same.
2. Description of the Related Art
Carbonaceous composite materials, which are excellent in chemical resistance, heat resistance and machinability as well as in self-lubricating properties, are regarded with interests as sliding members, for example, and are widely used, including electric sliding brushes for generators (hereinafter they are simply referred to as “brush”); bearings for various kinds of devices; and mechanical sealing rings. Recently, the devices are often used in even more harsh conditions or extreme environmental conditions and, besides, are demanded for high reliability and life extension. To meet the demands, the carbonaceous composite materials are growing in development. One of the carbonaceous composite materials, which have developed as part of the development, is a carbonaceous composite material to which graphite fluoride is added. It is known that the addition of graphite fluoride can largely contribute to improvement of abrasion resistance and self-lubricating properties of the carbonaceous composite materials and is particularly preferable as the sliding members (Japanese Laid-open Patent Publication No. Sho 55-116609).
However, the brushes made from the carbonaceous composite material in which graphite fluoride was added have been found to have great problems when actually assembled in a motor to use them. Those are the problems that in use, a decomposed product of the graphite fluoride produced in the brush, i.e., fluorine, escapes out and reacts with moisture (water) in the air to thereby produce hydrofluoric acid, which in turn can produce detrimental effects. Specifically, not only the event that the produced hydrofluoric acid causes corrosion of a commutator (made of copper) of the motor to progress in a short time but also the so-called secondary corrosion of various kinds of metallic members around the brush being corroded gradually are caused.
In addition, the graphite fluoride is very much expensive, so manufacturing costs for the sliding members are largely influenced by even a few percent of variations of the additive ratio. For this reason, it is necessary to determine the limits on the additive ratio of graphite fluoride so that high sliding performance can be obtained with a minimum additive ratio, for production of the sliding members of cost efficiency.
In the light of the circumstances mentioned above, the present invention has been made. It is the objective of the present invention to attempt to provide (i) a carbonaceous composite material that can fully provide the characteristic effect of the graphite fluoride containing carbonaceous composite material with a minimum additive ratio of graphite fluoride and simultaneously can provide the secondary corrosion inhibiting properties and (ii) a sliding member using the same.
SUMMARY OF THE INVENTION
A carbonaceous composite material of the present invention features in that it comprises graphite fluoride; and alkaline agent for neutralization of hydrogen fluoride or absorbent for fixation of hydrogen fluoride, the remainder being carbonaceous components.
The sliding member of the invention is the one made by using the carbonaceous composite material of the invention. Specifically, the carbonaceous composite material of the invention is applicable to an electric sliding brush, a mechanical sealing member, a bearing member and the like.
The graphite fluoride is added to improve the sliding properties of the carbonaceous composite material. The alkaline agent for neutralization of hydrogen fluoride or the absorbent for fixation of hydrogen fluoride is added to suppress occurrence of the secondary corrosion resulting from fluorine which is the decomposed product of the graphite fluoride.
It is preferable that the content of the graphite fluoride is not more than 1.0 mass % in that the content of graphite fluoride exceeding 1.0 mass % can no longer produce any noticeable improvement in sliding properties.
Further, for removing the liberated fluorine from the graphite fluoride most efficiently, it is preferable that the content of the alkaline agent for neutralization of hydrogen fluoride or the content of adsorbent for fixation of hydrogen fluoride is substantially equal to the content of the graphite fluoride.
The alkaline agents for neutralization of hydrogen fluoride including at least one alkaline agent selected from the group consisting of oxides of alkali metals or alkaline earth metals and hydroxides. Particularly, the alkaline agents for neutralization of hydrogen fluoride is preferably at least one alkaline agent selected from the group consisting of lithium oxide, calcium oxide, lithium hydroxide and calcium hydroxide.
The adsorbents for fixation of hydrogen fluoride include at least one absorbent selected from the group consisting of fluorides of alkali metals or alkaline earth metals. Particularly, the adsorbent for fixation of hydrogen fluoride is preferably sodium fluoride.
REFERENCES:
patent: 3717576 (1973-02-01), Hiratsuka et al.
patent: 3776845 (1973-12-01), Watanabe et al.
patent: 4333977 (1982-06-01), Abrahams et al.
patent: 4626365 (1986-12-01), Mori
patent: 4655944 (1987-04-01), Mori
patent: 5089154 (1992-02-01), King
Miyoji Arai
Nobuatsu Watanabe
Tadashi Murata
Tetsuro Tojo
Toshiyuki Miyatani
Howard Jacqueline V.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Toyo Tanso Co., Ltd.
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