US1442910A - Electrically-heated vessel - Google Patents

Description

Jan. 28, 1923. 1,442,910,

I A. STEINHARDT. 1

ELECTRICALLY HEATED VESSEL.

FILED AUG.29, 1921.

gag/Ll MI OrZ/Zurd'feiniardl mwm 'M/WM Patented Jan. 23, 1923.

UNITED STATES ARTHUR STEINHARDT,

OF BERLIN, GERMANY.

ELECTRICALLY-HEATED VESSEL.

Application filed August 29, 1921. Serial No. 496,526.

1 0 all whom. it may concern:

Be it known that I, ARTHUR STEINHARDT, a citizen of Germany, and residing at Berlin, Germany, have invented certain new and useful Improvements in Electrically-Heated Vessels (for which I have filed applications in Germany, September 11, 1919, Patent No. 340,211; Czecho-Slovakia, July 26, 1921; France, July 28, 1921, and Great Britain, July 28, 1921), of which the following is a specification.

My invention relates to improvements in electrically heated vessels made from ceramic matter and in-the method of making the same, and the objects of the improvements are to provide a vessel in which the heating conductor is entirely confined in ceramic matter, in which the water has no access to the conductor and surrounding parts, in which the conductor is embedded in a reliable insulation so as to avoid loss of energy and short-circuits, in which the conductor is not injured by the baking process, and in which the ceramic matter embedding the conductor is not injured by nonuniform expansion by heat. VV'ith these and other objects in view my invention consists in manufacturing the body of the vessel from suitable ceramic matter of ordinary composition, baking the same at high temperature, applying the conductor thereon, covering the conductor by means of ceramic matter similar as to its composition and physical properties to the matter from which the body is made but having a larger proportion of a fluxing medium added thereto for reducing the melting or fusing temperature to a point which is not injurious to the conductor, and finally again baking the vessel with the conductor and ceramic coating applied thereto at a temperature Fig. 2, is a vertical section showin another form.

Referring at first to the example shown in Big. 1, my improved vessel consists of a body a of ceramic matter having at the lower part of its side wall a portion 6 of reduced diameter, an electrical conductor d celled around said portion of reduced diameter and made from a suitable material adapted to transform the electric energv into heat, two terminals 6 connected respedtively to the ends of the conductor d and fitted in a block 7 of insulating material, a collar 9 likewise of ceramic matter filling the groove around the portion Z) of reduced diameter and covering the electric conductor (1, and a handle 2' made integral with the body a. The body a consists of a suitable ceramic matter of known or preferred composltlon, such as porcelain, clay, and the like, and composed for example of matter such as kaolin, feldspar, quartz, etc. The collar 9 consists of a matter which has a similar composition as the body a, which however has a larger proportion of a flux mg medium of media added thereto such as oxids of magnesium, sodium, lead, boron and a small amount of chlorid of sodium and water glass. Such media are adapted considerably to change the melting or fusing properties of the composition the fusing temperature corres onding for example to 0 12 or 0 13 of egers scale (that is to say, about or 835 Centigrade respectively) and in addition they have the functlon to impart to the mass being baked a degree of shrinkage and a coefficient of expansion which nearly correspond to the physical properties of the mass from which the body is made, and which in the finished vessel impart to the parts thereof substantially the same coetficient of expansion. It will therefore be understood that the composition of the matter g depends in each case on the composition of the mass a and the physical properties thereof and and more particularly on the shrinkage, coefficient of expansion, and the fusing temperature. In one example the body a is composed of 48% clay matter, 40% quartz, and 12% feldspar. If the conductor d consists of the alloy known in the trade under the name of nichrom, a suitable composition of the protecting layer is: I

0.1 Na,() 0.3 K 0 0.4 Mg() 0.2 Ca@ 0.4 A1 0 2.6 Sit),

the like at the temperature required for fusing the matter. This temperature is such as is necessary in each case according to the character of the composition. and in case of porcelain it is say l380 (3., which temperature would of course be destructive to a conductor of any composition. Thereafter the body a is glazed internally and externally preferably however with exception of the outer surface of the portion b of reduced diameter. Now the conductor d is coiled around the portion 1; the surface of which is preferably formed with a helical groove h for embedding the conductor therein, and the conductor is connected to the terminals 6 embedded in the block f. Finally the portion of'reduced diameter is filled out with a ceramic matter 9 having in the present example the composition stated above, and the vessel is again brought into a kiln and heated to a temperature which is far below the temperature at which the body has before been baked, for instance to 835 or 855 centigrade, as referred to above. By the mass 9 the groove around the portion of reduced diameter is preferably filled out to the diameter of the'body a, and the mass should not be too wet, a state similar to resin being preferred in most cases. I have found that the mass adheres very well to the non-glazed surface of the portion b, and that after baking the masses a and-g are practically an integral body. In some cases the outer surface of the mass 9 is glazed. In a modification of the invent-ion the first glazing of the body a 15 omitted and the complete vessel is glazed after baking the mass 9.

In the construction shown in Fig. 2 the conductor d is embedded in a spiral'groove k formed in the bottom 0 of the body a and the protective mass is likewise applied to the said .bottom. The body is .formed at its bottom with a. flange k, The

Fig 1.

referably the terminals 6 are displaced relatively to the handle 71 at an angle of 90, and they are placed horizontally 'one beside the other, the arrangement shown in the figures being made only for convenience of illustration.

In addition to the advantages stated above it will be noted that the cost of manufacture is low, because in any case the use 'of expensive metals such as nickel, copper, and their alloys is reduced to a minimum, and it is entirely avoided in such cases in which the conductor (1 consists of a siliconcarbon compound such as products known under the trade names of silit, silundum, carborundum, and the like.- Finally, the cost of manufacture is materially reduced as compared to vessels made from metal.

While in describing the invention reference has been made to particular examples embodying the same, I wish it to be understood that my invention is not limited to the forms of'heating apparatus and to the methods described and that various changes may be made without departing from the having suitable fluxing media admixed the're-- to and baked at reduced temperature.

2. The herein described electrical heating apparatus, which consists of a body made from ceramic matter of high fusing temperature and baked at high temperature, an

electric conductor, and a protective layer of ceramic matter for said conductor having a composition similar to that of the body and having its fusing temperature reduced'by having suitable fiuxing media admixed there to and baked at reduced temperature and having a shrinking property and coeflicient of expansion similar to those of the matter of the body.

3. The herein described method of manufacturing electrical heating apparatus, which consists in moulding a body from ceramic matter, baking said body, applying thereto an electric conductor and ceramic matter embedding the same and consisting of a compositionsimilar to that from which the body is made and having added thereto a suitable fluxing medium adapted to reduce its fusing temperature to a point whichis not injurious ramic matter.

4. The herein described method of manufacturing electrical heating apparatus, which consists in moulding a body from ceramic matter, baking said body, applying thereto an electric conductor and ceramic matter embedding the same and consisting of a composition similar to that from which the body is made and having added thereto a suitable fluxing medium adapted to reduce its fusing temperatureto a point which is not injurious to the conductor and having a coefficient of expansion similar to that of the body, and

baking the body-and the ceramic matter applied thereto at a temperature suflicient to fuse the applied ceramic matter.

5. Theherein described method of manufacturing electrical heating apparatus, which consists in mouldinga body from ceramic matter containing kaolin, quartz, and feldspar, baking said body, applying thereto an electric conductor and ceramic matter embedding the same and consisting of a composition containing kaolin, quartz, feldspar, and oxids of magnesium, sodium, lead, and boron, the amount of such fluxing media being suflicient to reduce the fusing temper ature to a point which is not injurious to the conductor, and baking the body and the ceramic matter applied thereto at a temperature suflicient to fuse the applied ceramic matter.

In testimony whereof I hereunto aflix my signature in the presence of two witnesses.

ARTHUR STEIN HARDT.

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