|Publication number||US2022314 A|
|Publication date||Nov 26, 1935|
|Filing date||Dec 29, 1933|
|Priority date||Dec 29, 1933|
|Publication number||US 2022314 A, US 2022314A, US-A-2022314, US2022314 A, US2022314A|
|Inventors||Heyroth Albert H, Schildhauer Walter E|
|Original Assignee||Globar Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (11), Classifications (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Nov. 26, 1935.
A. H. HEYROTH ET AL ELECTRICAL RESISTOR AND ITS MANUFACTURE Filed Dec. 29, 1953 IN VENTORS.
Patented Nov. 26, 1935 UNITED STATES PATENT OFFICE ELECTRICAL RESISTOR AND ITS MANUFACTURE I New York Application December 29, 1933, Serial No. 704,584
This invention relates to electrical resistors, more particularly to resistors intended for use as heating elements and radiators, and to methods of making the same.
Electrical resistors for use in radiating heat are ordinarily made by wrapping wire composed of refractory metal on refractory supports. Very satisfactory non-metallic radiators are made in the form of rods composed mainly of silicon carbide. These rods require support only at their ends. Both the metal wire resistors and the resistor rods are ordinarily operated at temperatures in excess of 500-600 C.; that is, at temperatures which produce a dull red to a bright red tint in the resistor.
One of the objects of our invention is to provide an electrical resistor for use at temperatures extending up to a dull red heat and in which the heat is distributed from a comparatively large area. Another object of our invention is to produce a resistor at low cost by simplification of the methods of manufacture.
The invention is illustrated by means of the accompanying drawing in which:
Figure 1 is a side view of a resistor made according to our invention;
Figure 2 is a section taken on the line 11-11 of Figure 1;
Figure 3 is a section taken on the line IIIIII of Figure 1;
Figure 4 is a side view of a resistor which is similar to that shown in Figure 1 except in the mounting or support for the resistor, a strip of ceramic material being substituted for the tube;
Figure 5 is a section on the line V-V of Figure 4;
Figure 6 is a side view of a U-shaped resistor which is mounted on a ceramic support; and
Figure 7 is a section on the line VII-VII of Figure 6.
Referring to the drawing in detail, 2 represents an insulating tube of refractory material such as is used, for example, in clay insulators. On the outside of this tube is a conducting coating composed principally of silicon and a form of clay known as bentonite. This is a. clay-like material which has a large power of absorption of water and which is easily fusible after drying. On the terminal portions of the conducting coating are layers 4 of highly conducting metal. These may be produced, for example, by electroplating copper on the terminal portions of the resistor or by spraying brass or other conducting metal which is easily sprayed. The spraying can be performed with a Schoop gun.
As an illustration of a method of making our improved resistor, an unglazed clay tube or ceramic body of the shape and dimensions desired for heat distribution is selected. Metallic silicon is ground to about 200 mesh (meshes to the linear inch). About 84 parts of this finely divided silicon are mixed with 16 parts of bentonite, and the mixture of silicon and bentonite is dispersed in about twice the mass of water with the aid of an agitator until a slurry suitable for application to the unglazed clay tube (or other form of ceramic body) is formed. The slurry may be applied by dipping the ceramic body in the dispersion or the slurry may be painted on the surface of the tube. After the first coating has dried, a. second coating can be applied and the process repeated a number of times depending on the degree of conductance which it is desired to obtain in the finished product. The coated tube is then placed, for example, in a muffle and fired at a temperature of about 2300" F. The silicon will remain substantially unaltered even in an oxidizing atmosphere if not heated too long at the temperature mentioned. About twenty minutes firing is needed for a tube six inches long and five eighths of an inch in diameter. The resultant coating has a hard, smooth surface which is not easily scratched. Terminals of high- 1y conducting metal are provided by electroplat- 3o distributed from a substantially plane surface which is heated more uniformly than is possible with the use of a wire grid, for example.
In the modification shown in Figures 6 and 7, a strip of ceramically bonded refractory is covered with a U-shaped resistor layer 8. The ends of the resistor layer are provided with terminal connections 9 and 9' at the respective ends by depositing or spraying highly conducting metal on the terminal portions of the resistor layer. The coating at the U-shaped bend ll may be made narrower or thinner than the remainder of the resistor coating so that this area becomes red hot while the remainder of the resistor is cooler. This affords a convenient method of localizing heat on an outstanding area.
Our resistor has a number oi advantages. both from the manufacturing point oi view and an an electrical resistor.
ing and described above as an electrical resistor,
some or the advantages are:
Low cost of replacement;
* the oi metal wire heater temperature are distributed Z and nil-lg, The resistor can be wiped and the like without injury to resistor.
:se of distribution oi radiant iesiritcr, it: is mounted, ior mu 3; position that its longitudinal i el coincides with the focal axle t wing a principal section. which ril- UCLU theaiahandterminalmetaletrlpeattachedto the sides 0! the U-shaped coating.
2. The method of making an electric heater which comprises making a slurry of approximate- 1y five parts of finely divided silicon and one part 0! nnely divided bentonite in a mass or water which is greater than that of the tinely divided solids, applying the slurry to the two oppoaite sides of a refractory slab which is an electrical insulator and applying also a thinner coating of the slurry to the curved suriace which joins the said opposite sides, baking the coating on the mounting at a. temperature exceeding 2000 Fahrenheit, and spraying highly conducting metal on the opposite sides of the U-shaped resistor thus formed.
3. An electric heater comprising a refractory base in the term ci a non-conducting 'slab having a rounded end, a conducting layer composed of silicon and a seli-fluxing binder baked metal strips attached to the sides oi the U-shaped coating.
4. The method 01' making an electric heater 1 which comprises making a slurry of finely divided silicon and a smaller proportion or self fiuxing binder in a mass 01 water which is great-- or than that of the finely divided solids, applying the slurry to the two opposite sides of a reiractory slab which is an electrical insulator, and applying also a thinner coating of the slurry to the curved surface which joins the said opposite sides, baking the coating on the mounting at a temperature exceeding 2000 Fahrenheit, and
spraying highly conducting metal on the opposite sides of the U-shaped resistor thus formed.
ALBERT H. HEYROTH. WALTER E. SCHHDHAUER,
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|U.S. Classification||338/309, 338/333, 501/130, 338/327, 219/543|