Improved Compositions for use in the Construction of Electrical Heating Apparatus and Resistances, and the Processes for their Manufacture.
Year: 1897

page_text: Date of Application, 2nd Nov., 1897-Accepted, 2nd Nov., 1898
COMPLETE SPECIFICATION.
Improved Compositions for use in the Construction of Electrical
Heating Apparatus and Resistances, and the Processes for their
Manufacture.
I, LOUIS PARVILLEE, of 29, Rue Gauthey, Paris, in the Republic of France,
Manufacturer of Porcelain Goods for Electrical and other purposes, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
It is known that by intimately mixing metallic powders with substances which
are non-conductors of electricity, products are obtained of which the electrical
resistance varies, according to the nature and proportion of the materials employed.
The formula which I have adopted up to the present time for the manufacture
of compositions upon the above principle, gives uncertain results. In practice,
the conductibility of the compounds alters under the prolonged influence of the
electric current and the increase in temperature; oxidation occurs, the compo-
sition becomes less and less homogeneous, fusion takes place at various points and
fractures frequently follow sudden alterations of temperature. Those portions of
the composition to which the contacts are attached undergo alterations and spark-
ing soon takes place, bringing about the complete destruction of the parts."
My present invention is based upon the following formula, which produces com-
positions suitable for electrical heating apparatus and the manufacture of resis-
tances in general, of a very superior character and free from any of the objections
above described.
These materials after being intimately mixed and dried till they contain not
more than about 6 per cent. of water, are compressed in suitable moulds with a
pressure of not less than 3,000 kilos. per square centimetre, and the moulded
articles are then baked with charcoal in a suitable closed receptacle, at a tempera-
ture a little below the melting point of nickel.
Articles manufactured in accordance with this process can be made of any re-
quired form and dimensions.
Those parts of the articles to which the contact devices are connected, are rein-

page_text: forced by the application to them at the time of compression of the following
special composition.
FORMULA Na 5
Such treatment insures a very much better conductibility at the points of con-
tact, and consequently avoids the danger of sparking between the metallic contact
pieces and the composition.
If preferred, in place of the above treatment, copper or other suitable metal may
be electrically deposited upon those parts of the article to which the contacts
are to be fixed, to increase the conductibility at such points.
The specific resistance of compositions, formed as above described, may vary
within considerable limits, according to the fineness of the metal employed, the
degree of compression and the temperature of baking-so that with the same for-
mula, articles may be produced having the same dimensions, but differing greatly
in their electrical resistance.
Articles having the composition set forth in the above formulae and manufac-
tured according to the above processes, are intended for use in the construction
of domestic or industrial electric heating apparatus, and generally speaking for
the construction of rheostats and electrical resistances of any kind.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim, is-
1. The process for the manufacture of articles of the class described, consisting
of the combination of 60 parts of powdered nickel with 40 parts of plastic white
clay, compression of the mixture so obtained in moulds and finally baking with
charcoal in a suitable receptacle, all substantially in the manner and for the
purposes as herein set forth.
2. The process for the manufacture of articles of the class described, consisting
of the combination of 60 parts of powdered nickel with 40 parts of plastic white
clay, compression of the mixture so obtained in moulds, application, before com-
pression, to certain parts, of a combination of 90 parts of powdered nickel with
10 parts of plastic white clay, and finally baking with charcoal in a suitable re-
ceptacle, all substantially in the manner and for the purposes as herein set forth.
3. The process for the manufacture of articles of the class described, consist-
ing of the combination of 60 parts of powdered nickel with 40 parts of plastic
white clay, compression of the mixture so obtained in moulds, baking with char-
coal in a suitable receptacle, and finally the application to certain parts, of copper
or other suitable metal by electro-deposit, all substantially in the manner and
for the purposes as herein set forth.
4. As a new article of manufacture, the improved compositions for use in the
construction of electrical heating apparatus and electrical resistances in general,
made in the manner and in accordance with the processes herein described and
claimed.
AMBROSE MYALL,
2, Lancaster Place, London, W.C., Agent for the Applicant.