Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Patent
1990-06-28
1991-12-31
Niebling, John
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
2041802, 2041809, 204299EC, 118429, C25D 704
Patent
active
050769057
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to deposition apparatus, and particularly to apparatus for use in the deposition of a cup-shaped body from a slurry.
DESCRIPTION OF THE PRIOR ART
It is sometimes necessary to produce by deposition, for example electrophoretic deposition, a cup-shaped.body, that is a tubular body having a closed end, and a difficulty which arises is in achieving a substantially uniform deposition in order to produce a body in which the tubular wall and the end wall are of substantially the same even thickness.
Such cup-shaped bodies are used as membranes in sodium-sulphur electrochemical cells, where a cup-shaped body of beta alumina material is used as a solid electrolyte separating the liquid sodium and sulphur materials. Such a cell is described in GB-A-2178889.
For deposition a mandrel is placed in a slurry comprising the material to be deposited suspended in a carrier liquid. If the necessary deposition is to take a realtively long time, for example more than 1 minute, then it is necessary for the slurry to be agitated, for example by the use of magnetic stirrers, in order to prevent the material to be deposited settling out of suspension. However, such agitation can result in deposited material being removed from the mandrel, and thus it is preferable to use an apparatus in which the slurry is pumped around a closed circuit containing a deposition chamber in which the mandrel is located.
STATEMENT OF THE INVENTION
According to this invention there is provided an apparatus for use in the deposition of a cup-shaped body from a slurry, comprising a chamber having a slurry inlet and a slurry outlet, and a mandrel mounted in the chamber, on the outer surface of which mandrel the cup-shaped body is deposited as slurry flows from the inlet to the outlet, including control means to provide a substantially uniform slurry flow rate over all surfaces of the mandrel on which deposition is to take place.
Preferably when the apparatus is used for electrophoretic deposition the control means also serves to provide a substantially uniform electric field over surfaces of the mandrel on which deposition is to take place.
The chamber can have a slurry inlet at a lower end, a first slurry outlet at an upper end, and a second slurry outlet at the lower end, the mandrel being mounted in the chamber to define a space between the outer surface of the mandrel and the inner surface of the chamber, the first outlet surrounding the mandrel and the second outlet being below a bottom face of the mandrel and having a mouth extending over substantially the whole area of the bottom face of the mandrel.
With such apparatus the flow of slurry from the inlet to the first outlet serves for deposition of the side wall of the cup-shaped body on the mandrel, while the flow of slurry from the inlet to the second outlet serves for deposition of the end wall of the cup-shaped body on the bottom face of the mandrel. During such deposition the control member serves to provide a substantially uniform flow over the whole of the bottom face of the mandrel whereby a substantially uniform thickness end wall for the cup-shaped body is deposited.
Preferably the apparatus includes a slurry flow controlling member mounted at the lower end of the chamber and having the second outlet therein, the flow controlling member having a conical downwardly facing outer surface facing a corresponding surface of the chamber to provide an annular space constituting the slurry inlet to the chamber.
With such apparatus it is ensured that slurry entering the chamber does so in a manner giving satisfactory flow over the mandrel.
Preferably the chamber comprises a base member having the inlet and the second outlet therein, and a tubular wall member mounted on the base member.
The apparatus is particularly useful for carrying out electrophoretic deposition, in which case the chamber can constitute one electrode and the mandrel constitute the other electrode for the electrophoretic deposition process.
With such an apparatus the control mea
REFERENCES:
patent: 4092231 (1978-05-01), Chronberg
patent: 4246088 (1981-01-01), Murphy et al.
patent: 4376031 (1983-03-01), Andrus et al.
patent: 4436594 (1984-03-01), Nishida et al.
patent: 4791880 (1988-12-01), Aigo
Proceedings: DOE/EPRI Beta (Sodium-Sulfur) Battery Workshop VI, May 19-23, 1985, Snowbird, Utah.
Chloride Silent Power Ltd.
Niebling John
Ryser David G.
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