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Publication numberUS3665598 A
Publication typeGrant
Publication dateMay 30, 1972
Filing dateDec 17, 1970
Priority dateDec 17, 1970
Publication numberUS 3665598 A, US 3665598A, US-A-3665598, US3665598 A, US3665598A
InventorsBrieko Meindert Willem
Original AssigneeBrieko Meindert Willem
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of making a heating body
US 3665598 A
Abstract
Electrical resistance heating conductor, surrounded by an electric insulating cylindric layer of borium nitride or beryllium oxide, coated off by outward heat dissipating liner.
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Claims  available in
Description  (OCR text may contain errors)

United States Patent 1 51 3,665,598

Brieko 1 May 30, 1972 54] METHOD OF MAKING A HEATING 3,121,154 2 1964 Menzies et al. .219/552 )4 BODY 3,356,834 l2/l967 Mekjean 3,492,463 1/1970 De Wringer et a]. ..219/553 Inventofl Melndefl Wlllem Brick", p 3,513,539 5/1970 Davis ..29/61 1 brockslraat schasen, Netherlands 3,5 14.850 6/ 1 970 Barber et a]. ..29/599 [22] Filed: Dec. 17, 1970 Primary Lxammer-Vulodymyr Y. Mayewsky [21] Appl. No.: 99,048 AuorneyCushman. Darby & Cushman 521 11.5. c1 ..29/611, 99/195, 2 19/552, [571 ABSTRACT 338/243, 2l9/5 34 Electrical resistance heating conductor, surrounded by an [51] Int. Cl. ..HOlv ll/00 electric insulating cylindric layer of borium nitride or berylli- [58] Field of Search ..2 l 9/553, 534, 548, 552, 553; um oxide, coated olT by outward heat dissipating liner.

Between conductor, 1ntermed1ate layer and outward l1ner are at all times shrinking fits sustained. Conductor and liner con- [56] Rderences Cited sist of austanitic stainless steel, molybdenum, nickel, chromi- UNITED STATES PATENTS um, vanadium, rhenium, tungsten or its alloys.

2,001 ,848 5/1935 Nyquist v.29/[95 l Claim, 3 Drawing Figures PATENTEDHM 30 I972 3. 665, 598

IN V E N TOR M'l/VDEZT Mamie/sea ATTORNEYS METHOD OF MAKING A HEATING BODY The invention relates to a heating body, consisting of an electrical resistance element containing a conductor resistance surrounded by an electrical insulating layer, which insulating layer has a metal outer layer placed around it for delivery of the heat produced, in which below working temperature there is a contraction joint between the metal outer jacket and the insulating layer, while in addition, at room temperature, there is a contraction joint between the conductor resistance and the insulating layer.

Heating bodies of this kind, however, still show in present practice the drawback that for numerous applications the heat-loading capacity as expressed in watts/cm is not sufficiently high. According to the invention it is possible to attain a high heat-load, viz. a heat-load of the order of about 500 watts/cm, at a wall temperature of about 600-960" C., in that the heating body is executed in such a form of construction that its insulating layer is made of boron nitride, in which construction both the conductor resistance and the metal outer layer are made of austenitic stainless steel, molybdenum, nickel, chromium, vanadium, rhenium, tungsten or their alloys. Beryllium oxide may also be used to advantage as electrical insulating material instead of boron nitride.

It is highly advantageous for this purpose that even at working temperature there is still a contraction joint and hence a surface pressure between the outer jacket and the insulating layer. This surface pressure is very important during the working temperature, as it is only by such pressure that delivery of the heat produced is ensured. This pressure, in conjunction with the close fit of the contraction joint, furthermore ensures that the output geometry of the heating body is maintained.

This is important, because in this way local cavities, often formed as a result of deficient contacting, or a non-symmetrical geometry created by the swaging process to which the ele ment was subjected, can be prevented. Such non-symmetries and local cavities may in practice give rise to hot spots which adversely affect the loading level.

As there is also a contraction joint between the conductor resistance and the insulating layer placed around it, viz. a contraction joint which already exists at room temperature, the loading level may be increased.

This is, however, subject to the condition that even when cold there must be close contact between the conductor resistance and the insulating layer. It is therefore expedient to bring about a light contraction joint between the conductor resistance and the insulating material.

The contraction joint mentioned can most effectively be obtained by making a heating body according to the specified embodiments in such a way as to start with a tube of austenitic stainless steel, molybdenum, nickel, chromium, vanadium, rhenium, tungsten or alloys of these materials, after which this tube is rigidly shrunk around a cylinder of the electrical insulating material used, consisting of boron nitride or beryllium oxide. As this cylinder is a solid one, a contraction joint of this kind with a rigid contraction fit at about 250 C. can be executed without the risk that the boron nitride or beryllium oxide might show dislocations.

After subsequently cooling of the assembly described, the central part of the cylinder of the electrical insulating material used is removed by drilling, so that afterwards a cylindrical jacket of the said electrical insulating material is obtained which, by means of a contraction joint, is surrounded by a cylindrical jacket of austenitic stainless steel, molybdenum, nickel, chromium, vanadium, rhenium, tungsten or their alloys.

Next, after the inner side of the cylindrical jacket of the electrical insulating material used has been finished in a precise manner, this assembly of coaxial cylindrical jackets is shrunk at a temperature of 100 C. with a light contraction fit around a resistance conductor likewise composed of austenitic stainless steel, molybdenum, nickel, chromium, vanadium, rhenium, tungsten or an alloy thereof.

in this connection it should be noted that the high-loaded electrical heating elements known so far have at times failed in practice. This was generally caused by the fact that either local cavities were formed as a result of differences in thermal expansion or by chemical reactions, or because the thickness of the insulating layer was generally not uniform, or because the insulating material was not homogeneous in its characteristics. By applying the above-described method in the production of a heating body according to the invention, the drawbacks attaching to the heating elements known so far are surmounted, since production starts with a cylindrical tube, made of full material, of the electrical insulating material used. In addition there is the advantage arising from the possibility of obtaining the desired necessary surface pressures by a correct choice of the contraction dimension, to be efi'ected with high precision.

The heating bodymade in this way proves capable of delivering a very high heat-flux, resulting in a heat-load up to about 500 watts/cm at a wall temperature roundabout 600C. --96() C.

By means of the heating body, liquid metals such as sodium, potassium, lithium or their alloys can be heated in a very suitable manner.

in particular, this heating body lends itself for heat-transmission experiment, with cooling by liquid sodium, to be carried out in a nuclear reactor or in an installation provided outside a nuclear reactor for simulation of the latter. This is due to the fact that the metal outer jacket of austenitic stainless steel, nickel, chromium, molybdenum, vanadium, rhenium, tungsten or their alloys is not in any way adversely attacked by the liquid metals.

in many cases the heating bodies according to the invention will have an external diameter of the order of about 6 mm or somewhat more. With this diameter it is possible to obtain a length of such a heating body of about 500 mm.

In the accompanying drawings,

FIGS. 1 and 2 are transverse sectional views of two different heating bodies constructed according to the invention;

FIG. 3 is a transverse sectional view of a third heating body which include a thermo-electric element.

In the accompanying figures, sections have been made over such a heating body.

Item 1 in FIG. 1 denotes the central resistance conductor, 2 is the insulating layer surrounding it and 3 the outer jacket, made of austenitic stainless steel, nickel, chromium, molybdenum, vanadium, rhenium, tungsten or an alloy of these materials.

The embodiment of FIG. 2 differs from the embodiment shown in FIG. 1 only in so far as the central resistance conductor l likewise possesses the form of a cylindrical jacket inside which a cylinder 4 is placed, in which other components (not illustrated) may possibly be included. There may, for instance, be channels in it for electrical conductors or for a fluid. Cylinder 4 may be made of a material having qualities suitable for this purpose.

FIG. 3 gives a construction which enters into account for the insertion of thermo-electric elements in the wall of the type of heating element described.

Thermo-electric elements of this particular kind may perform an important function, for instance, in heat-transmission experiments and in fissile lattice testing of nuclear reactors operating with liquid metals, when it is necessary to possess data regarding the wall temperature.

The range of temperatures in which this occurs is usually of the order of 600C to 900 C. According to a method used up to the present the thermo-electric element 5 was fixed in a groove 8 in the wall of the jacket 3, after which the remaining space was filled with soldering material. A suitable soldering material is found on the market under the name of "Coast Metal 52." This soldering material contains 4.5 percent of silicon, which has a fusion-point lowering effect. The soldering temperature is l ,025 C.

The covering of such therrno-electric elements usually consists of a stainless steel or inconel jacket with a wall thickness of the order of approximately 0.03 mm. Now it has been found that during the soldering process the jacket of the thermoelectric element has a tendency to pass into solution because of the silicon that is present. According to a further embodiment of the invention an additional tube 6 surrounding the thermo-electric element 5 is provided for the protection of this thin-walled jacket. in this way the risk of breakage of the thermo-electric element is reduced to a minimum.

The materials which enter into account for making the tube 6 are: stainless steel, nickel, chromium and tantalum or an alloy of these materials.

1 claim:

1. A method of making a heating body comprising providing a tube made of a material selected from the group consisting of austenitic stainless steel, molybdenum, nickel, chromium. vanadium, rhenium, tungsten or an alloy of these substances with another material or with each other, rigidly shrinking the tube around a solid cylinder of electrical insulating material so as to be in tight contact therewith, subsequently removing the central part of this cylinder by drilling to form a tubular assembly and shrinking the assembly obtained in this way around a conductor resistance so as to be in tight contact therewith, said conductor resistance being made of a material selected from the group consisting of austenitic stainless steel. molybdenum, nickel, chromium, vanadium, rhenium, tungsten or alloys of these materials.

I! I III 1' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,665 598 Dated 30 1972 Meindcrt Willem Brieko Tnventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet insert I30] Foreign Application Priority Data Netherlands 69/18891 Dec 17, 1979 Signed and sealed this 17th day of September 1974.

(SML) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-105O HO-SQ)

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2001848 *Oct 3, 1932May 21, 1935August R NyquistElectrode for arc welding
US3121154 *Oct 30, 1959Feb 11, 1964Babcock & Wilcox LtdElectric heaters
US3356834 *May 11, 1964Dec 5, 1967Hooker Chemical CorpProcess and apparatus for storing heat
US3492463 *Oct 19, 1967Jan 27, 1970Reactor Centrum NederlandElectrical resistance heater
US3513539 *May 21, 1968May 26, 1970Davis D J Co IncMethod of making a solder gun tip
US3514850 *Sep 16, 1968Jun 2, 1970Imp Metal Ind Kynoch LtdElectrical conductors
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3953923 *Dec 9, 1974May 4, 1976Lake Center IndustriesMethod of making heating device for liquids
US4031611 *Dec 15, 1975Jun 28, 1977Thermon Manufacturing CompanyMethod of making preinsulated pipe assembly
US4349727 *Oct 8, 1974Sep 14, 1982Southport Enterprises, Inc.Heater unit
US6872882 *Jul 16, 2002Mar 29, 2005W.E.T. Automotive Systems AgAreal electric conductor comprising a constriction
US20030010773 *Jul 16, 2002Jan 16, 2003Andreas FritzAreal electric conductor comprising a constriction
EP0083760A2 *Dec 15, 1982Jul 20, 1983Jobst Ulrich GellertInjection molding manifold member and method of manufacture
EP0083760A3 *Dec 15, 1982Aug 28, 1985Jobst Ulrich GellertInjection molding manifold member and method of manufacture
EP1006320A3 *Nov 17, 1999Sep 11, 2002SiCeram GmbHElectral instantaneous heater and method for making same
Classifications
U.S. Classification29/611, 219/534, 428/389, 428/366, 338/243, 219/552
International ClassificationH05B3/42, H01B7/00
Cooperative ClassificationH01B7/0054, H05B3/42
European ClassificationH05B3/42, H01B7/00G