US 2475379 A
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y 5 1949- G. E. STONG 2,475,379
ELECTRIC HEATING DEVICE Filed Dec. 18, 1946 Jnmnmr GUY .5 drama ttumzpa Patented July 5, 1949 ELECTRIC HEATING DEVICE Guy E. Stung Elmira, N. Y., assignmto Corning Glass Works, Corning, N. Y., a corporation of New York Application December 18, 1946, Serial No. 716,937
This invention relates to electric heating devices of the type comprising an electrically conducting iridized film of tin oxide supported on and in intimate contact with a base member of ceramic material such as glass. Such films are produced by heating the ceramic base member to 600700 C. and exposing it for ten to twenty seconds or more, while heated, to the fumes of stannic chloride or an atomized mist of stannous chloride solution. This process is commonly known as iridizing because the films are frequently iridescent in appearance. useful for some purposes, such as the generation of heat, but no satisfactory means has hitherto been devised for providing them with metallic terminals whereby substantial electric currents may be passed through the films.
The primary object of this invention is to provide spaced metallic terminals which are permanently united with the ceramic base member and which make non-resistant electrical contact with the iridized film.
According to the invention, spaced metallic terminals or members are supported on a ceramic base member, each metallic member consisting of a fired on metallized layer of silver intimately united with the base member and a fired on metallized layer of platinum intimately united with the base member adjacent to the silver and overlying the silver at least in part. A conducting iridized film of tin oxide is subsequently deposited by the above process on the base member between the metallic members and overlying the platinum of each metallic member and in electrical contact therewith. In order to pass an electric current through the iridized film, the metallic members or terminals may be connected by means of clamps or soldered joints to a source of electric current in the usual manner.
For a better understanding of the invention, reference is had to the accompanying drawing in which Fig. 1 is a plan view of a glass plate provided with spaced metallic terminals and a conducting iridized film between and over the terminals in accordance with the invention; and
Fig. 2 is an enlarged sectional view on the line 2-2 of Fig. 1, showing the iridized film greatly exaggerated.
In the drawing a ass p ate In is provided with Such films are glass in known manner.
2 metallized stripes II and I2 of silver and superimposed metallized stripes l3 and I4 of platinum and an overlying electrically conducting tin oxide iridized film l5. Silver stripes II and I2 which are in electrical contact with the film l5 through platinum stripes l3 and M are connected by clamps l6 and I! with a source of current (not shown).
The metallized stripes are formed by applying to the glass plate near its edges narrow strips of silver metallizing composition and firing it on the Narrow strips of platinum metallizing composition are thereafter applied so as to contact the glass adjacent the silver stripes and to overlie the. silver, at least in part. The platinum composition is then fired on in known manner. The silver and platinum metallizing compositions, known as "metallic lusters or "silver or platinum bright are well known and are readily available on the market.
When the conducting iridized film is subsequently' deposited on the glass plate and the metallized stripes, a good electrical contact exists between the film and the metal. A good electrical contact would not be obtained if the layer of platinum were omitted, because for reasons unknown the film, during deposition, becomes granular in structure at the junction of silver and glass. I have found that when this junction is covered with platinum the iridized film makes good electrical contact with the platinum and through it makes good contact with the silver.'
1. An article of manufacture comprising a ceramic base member, two metallic members supported on the base member in spaced relationship to each other, each metallic member consisting of a fired-0n metallized layer of silver intimately united with the base member and a fired on metallized layer of platinum intimately united with the base member adjacent to the silver and overlying the silver at least in part, an iridized film containing tin oxide and extending continuously from intimate contact with the platinum of one of said metallic members to intimate contact with the platinum of the other, and means connected with said metallic members for supplying electric current thereto.
2. An electric heating device comprising a 3 ceramic base member, an iridiaed tin oxide-containing illm supported on and in intimate contact with said base member, and two metallic electric terminals supported on said base memher in spaced relationship with each other, each such terminal consisting of a layer of silver intimately united with the base member and a layer of platinum intimately united with the base member adjacent to the silver and overlying the silver at least in part, the iridized mm extending continuously from intimate contact with the platinum of one of said terminals to intimate contact with the platinum of the other.
GUY E. STONG.
U 4 REFERENCES The following references are of record in the file of this patent:
UNITED STATES PATENTS