US2303514A - Vapor electric device - Google Patents

Description

Dec. 1, 1942. A. H. TOEPFER VAPOR ELECTRIC DEVICE Fild May 7, 1942 0, 4/ 0 MAVTU/i INVENTOR Hob/pl? hf 75e/7f6v".

WITNESSES:

Patented Dec. 1, 1942 VAPOR ELECTRIC DEVICE Adolph H. Toepfer, Wilkinsburg, Pa., assignor to Westinghouse-Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 7, 1942, Serial No. 442,067

10 Claims.

My'invention relates to a vapor electric device, and particularly to an improved make-alive e'le'ctrodeand means and methods of constructing such electrodes.

In the operation of vapor electric devices of the make-alive type, it is desirable to have makealive electrodes of similar physical and electrical characteristics so that all of the parallel operating valves of a make-alive type converter may have substantially the same operating characteristics. The materials heretofore found suitable for make-alive electrodes are of a hard abrasive physical characteristic and it has heretofore been difficult to produce a plurality of substantially similar electrodes.

It has been found that materials having substantially identical physical dimensions and a homogeneous physical characteristic have produced substantially similar electrical characteristics.

I have found that titanium oxide combined with certain stable insulating materials such as aluminum oxide or silica can be worked to produce stable make-alive electrodes having substantially identical physical and electrical char-.

acteristics so that a large number of substantially similar make-alive electrodes may be practically constructed.

t is an object of my invention to provide a make-alive electrode which may be easily re produced.

It is a further object of my invention to provide a method of constructing electrodes which will have substantially identical operating characteristics.

It is a further object of my invention to produce a low current reproducible make-alive electrode.

Other objects and advantages of my invention will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which:

Figure 1 is a schematic illustration of a vapor electric device embodying my invention;

Fig. 2 is a sectional elevation of a preferred form of my improved electrode; and

Figs. 3 and 4 are front and side elevations of a modification according to my invention.

In the illustrative embodiment of my invention, a discharge device having a suitable container I and spaced main electrodes, one of which is preferably a vaporizable reconstructing cathode II such as mercury or gallium and is provided with a make-alive electrode l2 normally in contact with the cathode material. The

Serial No. 404,888, filed July 31, 1941, and assigned to the same assignee as this application.

In constructing my improved'make-alive electrode [2, a working tip I5 is provided by making a water paste of powdered titanium oxide and astable insulating material such as aluminum oxide or silica. Preferably the insulatingmaterial is of the fineness of at least 120 mesh.

A satisfactory low current electrode was securedby combining titanium oxide and the insulating materialin a ratio of the order of 24 parts of titanium oxide to parts of the insulating material by weight. In order to mold the material into the desired shape, a water paste is made-having a consistency of the nature of modelling-clay or other easily worked mud.

In the preferred embodiment of my invention, the tip [5 is formed in a substantially conical shape and worked into intimate contact with a graphite head l6 which is preferably provided with a suitable aperture I! for connection to a conductor [8 from the impulsing system I3.

In order to reduce the energy required to operate the make-alive electrode, I prefer to provide the graphite head IS with a projection 19 or extension which extends downwardly into the active tip IE to provide a conducting core for distributing the current evenly to various parts of the active material.

The assembled electrode 12 is heat treated in a non-oxidizing or reducing atmosphere such as carbon vapor or hydrogen at a temperature of the order of 1000 to 1500 C. for a time of the order of thirty minutes to two hours to reduce the tip to a homogeneous high resistance material. While the tip 15 may be molded in any suitable manner, I prefer to mold the tip in a relatively thin metallic mold which is removed by melting off during the heat treating process. Care must be taken, however, to control the temperature as the resistance material tends to fuse at a temperature but little above the melting point of common ferrous alloys.

Instead of molding the acting material into conical shape, as shown in the preferred embodiment, according to Fig. 2, the mud mixture may be rolled into a relatively thin sheet and cut into preferably tapering segments 20 as shown in Figs. 3 and 4, and a connection made by inserting a suitable metal conductor 2| into the segment. It is desirable to utilize a metal such as molybdenum which has a low thermal coefiicient of expansion. The cutout segments 20 with their attached connecting wires 2| are heat treated in the same manner as the conical tips I5 to produce the high resistance homogeneous characteristic of the bonded electrode.

While for purposes of description I have shown and described preferred embodiments of my invention, it will be apparent to those skilled in the art that changes and modifications can be made therein without departing from the true spirit of my invention or the scope of the appended claims.

I claim as my invention:

1. A high resistant stable electrode for a makealive type device comprising a tapering tip of a high resistant mixture of titanium oxide and a stable insulating material, a head of graphite bonded to the base of saidtip, a projection on said head extending into said tip and providing a conducting core therein. 1

2. A make-alive electrode for an arc discharge device comprising a substantially conical electrode tip of high resistant material composed essentially of titanium oxide and aluminum oxide in the proportions of the order of twenty-four parts of titanium oxide to one hundred parts of aluminum oxide by weight.

3. A make-alive electrode for an arc discharge device comprising a substantially conical electrode tip of high resistant material composed essentially of titanium oxide and aluminum oxide in the proportions of the order of twenty-four parts of titanium oxide to one hundred parts of aluminum oxide by weight and a conducting connector having a portion extending into said tip.

4. Ina make-alive type valve, a make-alive electrode comprising -a graphite head, a composite tipsecured to said head, said tip composed substantially of titanium oxide and aluminum oxide in the proportion of twenty-four parts of titanium oxide to one hundred parts of aluminum oxide by weight.

5. A make-alive electrode for an arc discharge device comprising a molded body composed of a mixture of titanium oxide and aluminum oxide which has been heat treated in a reducing atmosphere at a temperature of the order of 1000 C. and a conductor connected to said body.

6. A high resistant stable electrode comprising a body composed of particles of a stable insulating material and titanium oxide powder bonded at a temperature of the order of 1000" C. in the presence of a reducing atmosphere.

7. A high resistant stable electrode comprising a body composed of particles of a stable insulating material and titanium oxide powder bonded at a temperature of the order of 1000 C. in the presence of a reducing atmosphere and a conducting connector bonded to said body.

8. The method of constructing a high resistant stable electrode which comprises forming a water paste of titanium oxide and a stable insulating material, shaping said parts into an electrode body, pressing a graphite head into firm contact with said electrode body and heat treating said body in a hydrogen atmosphere.

9. The method of constructing a make-alive electrode which comprises constructing a graphite head, securing to the head a tip composed of a mixture of aluminum oxide and titanium oxide and heat treating in a reducing atmosphere.

10. The method of constructing a make-alive electrode which comprises making a wet mixture compound of approximately twenty-four parts of T102 and one hundred parts of A1203 by weight, molding the mixture on a conducting body and firing the structure in a reducing atmosphere at a temperature of the order of 1000 to 1500 C.

ADOLPH H. TOEPFER.

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