Metallurgical apparatus – Means for melting or vaporizing metal or treating liquefied... – With means to discharge molten material
Reexamination Certificate
2000-02-02
2002-03-12
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Means for melting or vaporizing metal or treating liquefied...
With means to discharge molten material
C266S286000, C501S095200, C501S099000
Reexamination Certificate
active
06355206
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART
1. Field of the Invention
The present invention relates a novel SiC—C/C composite material usable as jigs for molten metal requiring oxidation resistance at high temperatures, such as molten metal carrying pumps used in molten metal or molten metal pumps for removing dross, grinding members requiring oxidation resistance at high temperatures, sliding members such as rolling bearings and plain bearings used in apparatuses for making semiconductors, precision instruments, cars and aircraft parts, and braking members used as friction materials for brake disks fitted so as to gear with speed control devices used for stopping or controlling of speed of mass-transportation means such as large cars, ultra-high speed trains, and aircraft. The invention further relates to a method for producing the composite material.
2. Related Art Statement
Aluminum-zinc alloys, SUS and other various alloys are used as jigs for molten metal, but since they are used at high temperatures, the life thereof is short, namely, about one week. Therefore, they must be frequently changed, and the changing operation at high temperature is very difficult. Thus, demanded are those materials which do not give substances contaminating the metal in the molten metal and are high in abrasion resistance, oxidation resistance and endurance, and can be used for a long period of time at high temperatures.
For example, plating of steel sheets for cars is carried out by dipping the steel sheets to be plated in metals such as zinc and aluminum molten by heating (molten metal). However, when the materials to be plated are repeatedly dipped, impurities in the molten metal grow in the form of particles to cause formation of solid suspended materials (dross) in the molten metal. If the plating is continued as it is, plating thickness becomes uneven or appearance of the plated articles becomes poor.
Therefore, in metal plating step, the plating operation is carried out with removing dross by a molten metal pump.
FIG. 9
shows an example of the molten metal pump. In
FIG. 9
, steel sheet
11
which is a material to be plated is plated by dipping it in molten metal
13
by means of pulley
12
in a hydrogen atmosphere. Molten metal pump
14
is generally provided with dross storage portion
15
and dross passage
16
having openings at both ends. One end opening of dross passage
16
communicates with molten metal
13
outside the dross storage portion
15
and another end opening of dross passage
16
communicates with molten metal
13
inside the dross storage portion
15
. Furthermore, the dross passage
16
has impeller
18
for bringing about a liquid flow from one end side to another end side fitted to revolving shaft
17
in another side of the dross passage. In the molten metal pump
14
shown in
FIG. 9
, the inner space of inner container
20
forms the dross storage portion
15
and the space between the inner wall of outer container
21
and outer wall of the inner container
20
forms the dross passage
16
.
Sliding materials such as rolling bearings and sliding bearings are widely used in various fields such as semiconductors, ceramics, electronic parts and manufacture of vehicles as constitutive members of apparatuses for making semiconductors, precision instruments, cars and aircraft parts. Especially, at present, with the rapid progress of technical innovation, sliding materials used for sliding bearings, sliders, bearing holders, etc. in the fields of space development such as shuttle spacecraft and spaceplanes, and fields of energy such as nuclear energy, solar energy and hydrogen energy, are used at high temperatures of higher than 400° C., at which oil cannot be used as a lubricant owing to burning or carbonization, or at low temperatures at which oil freezes. Therefore, sliding materials per se must have a kinetic coefficient of friction as small as possible and must hardly be worn. Furthermore, naturally, these sliding materials are required to have high strength and high reliability (tenacity and impact resistance) at moderate to high temperatures (200-2000° C.), and environmental resistance (corrosion resistance, oxidation resistance and radiation resistance). Moreover, due to the recent demand for energy savings, sliding materials are also required to be light in weight so that they can be driven by small loading.
Under the circumstances, silicon nitride or silicon carbide materials which are excellent in heat resistance and high in strength have hitherto been used as sliding materials, but these have a great kinetic coefficient of friction of 0.5-1.0 and are apt to cause wear of other materials and are not necessarily suitable as sliding materials. In addition, they are high in density and consume great energy for driving and have a large kinetic coefficient of friction. Moreover, they are brittle per se, and are considerably brittle if flawed and, moreover, have insufficient strength against thermal and mechanical shocks.
A s a means for solving these defects, ceramic composite materials (CMC) comprising composites of continuous ceramic fibers have been developed and used as sliding materials. These materials are high in strength a and tenacity even at high temperatures and have excellent impact resistance and environmental resistance, and, thus, they are being studied mostly in Europe and America as main refractory sliding materials.
On the other hand, as friction materials used in braking devices fitted to mass-transportation means such as large cars, ultra-high speed trains, and aircraft, carbon fibers-in-carbon often called C/C composites, which are very high in friction coefficient at high temperatures and light in weight, are widely used at present. In these mass-transportation means, it is common to continue braking for a long time depending on changes in driving circumstances or to repeatedly brake at high frequency. Therefore, in the case of braking devices using C/C composites as friction materials, the friction materials are exposed to high temperatures in the air for a long time. Accordingly, since friction materials using C/C composites are basically mainly composed of carbon fibers which readily burn at high temperatures, the carbon fibers react with oxygen under such conditions of being exposed to high temperatures for a long time to cause considerable wear or emission of smoke, leading to serious accidents. However, from the points of friction force at high temperatures and flexibility needed in fitting to disk brakes, substitutes therefor have not yet been discovered.
On the other hand, ceramic type SiC—C/C composite materials (CMC) comprising a composite of a ceramic matrix and fibers which are incorporated in the matrix have been developed in the following manner. That is, several hundred to several thousand ceramic long fibers of about 10 &mgr;m in diameter are bundled to form a fiber bundle (yarn), these fiber bundles are arranged in planar or three-dimensional directions to form unidirectional sheets (UD sheets) or various cloths, or these sheets or cloths are laminated, thereby forming a preform (fiber preform) of a given shape, and a matrix is formed in the preform by a CVI method (chemical vapor impregnation method) or an inorganic polymer impregnating and firing method or by filling the preform with ceramic powders by a cast molding method and then firing the preform to form a matrix.
As examples of CMC, there have been known C/C composites comprising carbon fibers arranged in planar or a three-dimensional direction between which matrices comprising carbon are formed, and SiC fiber-reinforced Si-SiC composites formed by impregnating a molded body comprising SiC fibers and SiC particles with metallic silicon. Moreover, British Patent No. 1457757 discloses a composite material obtained by impregnating a C/C composite with metallic silicon to form SiC. In this composite material, a very common material is used as the C/C composite forming a skeletal part. That is, a phenolic resin as a binder is coated on carbon fibers of a suitable th
Hanzawa Shigeru
Nakano Kenji
Burr & Brown
Kastler Scott
NGK Insulators Ltd.
LandOfFree
Sic-C/C composite material, uses thereof, and method for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sic-C/C composite material, uses thereof, and method for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sic-C/C composite material, uses thereof, and method for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2854377