US3307136A - Contact layer for a siliconcontaining material - Google Patents

Contact layer for a siliconcontaining material Download PDF

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Publication number
US3307136A
US3307136A US559309A US55930966A US3307136A US 3307136 A US3307136 A US 3307136A US 559309 A US559309 A US 559309A US 55930966 A US55930966 A US 55930966A US 3307136 A US3307136 A US 3307136A
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United States
Prior art keywords
layer
contact
aluminum
silicide
coating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US559309A
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English (en)
Inventor
Fitzer Erich
Rubisch Ottmar
Selka Friedrich
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens Plania Werke AG
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Siemens Plania Werke AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to NL128272D priority Critical patent/NL128272C/xx
Priority claimed from DES74922A external-priority patent/DE1144418B/de
Application filed by Siemens Plania Werke AG filed Critical Siemens Plania Werke AG
Priority to US559309A priority patent/US3307136A/en
Application granted granted Critical
Publication of US3307136A publication Critical patent/US3307136A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/02—Details
    • H05B3/06—Heater elements structurally combined with coupling elements or holders
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H05B3/148—Silicon, e.g. silicon carbide, magnesium silicide, heating transistors or diodes

Definitions

  • Silicon-containing materials are preferably employed for the production of very high temperatures.
  • electric heating elements consisting of silicon carbide or molybdenum silicide or titanium silicide or another high-melting (refractory) silicide of a transition metal from the fourth to sixth Bgro-ups of the periodic system of elements. It is a difiicult matter to reliably provide the body of such a heating element with a contact layer as required for connecting the element to an electric cable or other electric-current supply component.
  • the formation of the oxidation products results in a gradually increasing separation and loosening of the aluminum layer from the silicide-containing body and ultimately in an interruption of the electric contact.
  • the method according to the invention is partly similar to the above mentioned known methods in that it serves for producing a contact layer of aluminum or other metallic material havinga similar melting point, on a silicon-containing material consisting particularly of silicide carbide or a high-melting (refractory) silicide, preferably of molybdenumsilicide or titanium silicide.
  • a silicon-containing material consisting particularly of silicide carbide or a high-melting (refractory) silicide, preferably of molybdenumsilicide or titanium silicide.
  • the above-mentioned, shortcomings and difficulties are eliminated according to the invention by applying the contact layer in two steps or strata.
  • the contact location in cold condition is metallized, thus being coated with a thin layer, whose thickness is, about 0.1 to 0.5 mm. preferably.
  • a second layer of greater thickness isdeposited upon the first metal layer and consists of a contact material havingthe same or a higher melting point than the contact material used in the underlying metallizing coating, the
  • the first coating is deposited by metalspraying, for example, with the aid of a spray nozzle or extrusion nozzle, and then depositing the enveloping cover layerby casting it in molten form about the first deposited coatmg.
  • Another way of proceeding according to the invention is to deposit the first metallization of the contact area by applying the contact material electrolytically, by vapor deposition, thermal dissociation, or by cathode sputtering.
  • the contact material electrolytically, by vapor deposition, thermal dissociation, or by cathode sputtering.
  • vapor deposition thermal dissociation
  • cathode sputtering common to all these methods of deposition is the fact that the contacting area remains in cold condition, so that the formation of an oxide layer on the surface of the silicon-containing material is avoided. This is of utmost importance for the desired result of the method according to the invention.
  • the novel method according to the invention despite its particular simplicity, reliably eliminates the abovementioned diificulties heretofore encountered.
  • this method is preferably performed by subject ing the contact area of the silicon-containing body to grinding so that it assumes a smooth surface condition. Then, with the body in cold condition, a thin aluminum layer is sprayed onto the contact area. During spraying, the metal being sprayed solidifies even while traveling through the air, and its kinetic energy causes it to become plastically deformed when impinging upon the body, thus securing a firm adhering pressure of the aluminum particles against the body of the heater element.
  • the spray-deposited coating As long as the spray-deposited coating remains thin, it secures an excellent electrical contact. However, while such a thin coating suffices for establishing a good electric contact, it is in itself insutficient for reliable attachment of a terminal or other current conductor. This possibility, however, is afforded by the second, thicker layer which according to the invention is deposited in molten and hence liquid condition of the contact material. As mentioned, it is preferable to cast the cover layer about the spray-deposited thin layer. If for this purpose the contact location of the silicide-containing body is heated, an oxide coating will be formed, but now this oxide coating does not occur on the silicide-containin-g surface of the heater-element body proper but rather on the surface of the spray-deposited aluminum layer.
  • the oxide layer forming at this location is not detrimental.
  • the underlying spray-deposited aluminum layer becomes dissolved and liquefied and thus becomes bonded with the melt of aluminum being cast about the body under conditions which cause removal of the oxide skin previously formed on the underlying aluminum layer.
  • Any oxidic residue may then appear as a scum on the outer surface of the outer layer.
  • the same result can be obtained by substituting the casting of aluminum by immersion of the initially coated body into a mass of molten aluminum, or by embedding the initially aluminum-coated body in comminuted aluminum such as shavings, granules, or grains which thereafter are heated to the melting point of this embedding mass of aluminum.
  • the metal envelope produced in any of the waysaccording to the invention described above contracts to a greater extent than the siliconcontaining material of the heater element. Consequently,
  • FIG. 1 is a plan view of a complete heater element
  • FIGS. 2, 3 and 4 show partly in section, the ends of respectively different heater-element bodies
  • FIG. is alateral view of a contacted end of a heater element body with an electric cable attached thereto.
  • the main portion of the heater element shown in I FIG. 1 is constituted by the heater element proper and consists of the silicide-containing material, preferably of molybdenum silicide or titanium silicide.
  • the main portion has a hairpin-shaped major part 1 of smaller cross section than the respective ends 2 and serves to assume glowing temperature during operation.
  • the parts 2 consist of the same material and are integral with the part 1 but, due to their larger cross section, assume lower temperatures during operation.
  • the two end parts 2 are followed by the contact portions 3 which are continuations of the low-temperature parts 2 and consist of the same'silicide-containing material as the parts 1 and 2.
  • each cable 5 is enveloped in a contact layer and their respective ultimate ends 4 each form a terminal for connection'to a cable or, other conductor 5 consisting, for example, of aluminum wire strands.
  • a connector such as a terminal screw or bolt, joins thecable 5 with the end portion 3.
  • the outer end of each cable 5 is joinedwi-th a cable shoe .6 for accommodating a pressure screw or the like attaching means for connection of the heating element to current-supply busses.
  • a decisive advantage is the fact that after completion of this contact layer, no oxide layer is interposed between the contact layer and the end 10 of the heater element, because no oxide skin is formed when the metal layer 11 is being sprayed onto the cold heater element; whereas any oxide layer occurring during heating of the element body, already provided with the layer 11, occurs on this layer 11 and is dissolved and floated away when the layer 12 is cast about the body. For that reason, the method according to the invention reliably produces a sufficiently thick and strong contact layer of excellent adherence to the silicon-containing material of the heater element 10 proper.
  • the end of the silicide-containing body of the heater element to be provided with a contact layer is also of circular cross section but is given a shape which, seen from the glowing part of the element, first tapers toward the axis of the body and thereafter again widens.
  • Placed upon this part of of the element body is a thin aluminum layer 21 of essentially uniform thickness.
  • the portion 20 and the spray-deposited layer 21 of the heater element are surrounded by casting with an envelope .22 of aluminum whose outer surface is cylindrical.
  • the foregoing explanation of layers 11 and 12 in FIG. 2 is also applicable to the embodiment of FIG. 3.
  • the drawing here again shows the two layers as separate strata only for the purpose of lucid illustration.
  • the embodiment of FIG. 3 also corresponds to that of FIG. 2. :In addition, however, the embodiment of FIG. 3 affords the advantage of better resisting any mechanical pull in the direction of the longitudinal axis of part 20 and layers 21, 22. Consequently, the envelope 22 cannot'be stripped off for mechanical reasons of structure as Well as of metallic bonding.
  • the embodiment of FIG. 4 generally corresponds to The free end of the heater-element body is denoted .by 3b.
  • the spray-deposited thin layer of metal is designated as 31, and the thicker contact layer, cast about the layer 31, is denoted by $2.
  • the part is provided with regularly or irregularly shaped or distributed recesses 31% preferably of semispherical configuration.
  • the thin metal layer 31 is spray-deposited upon the surface of the part 30 with substantially uniform thickness throughout. 7
  • the contact layer 32 is cast about the body and is given an external cylindrical surface. In such I a design, the recesses in the body of the heater element
  • the operating temperatureof the glowing part I of 7 smaller cross section is at about 1700 C.
  • the low-temperature part 2 is then at temperatures between 309 C. and 700 C., naturally with a gradual transition zone between the. above-mentioned high temperature to the lower temperature.
  • aluminum or an aluminum alloy is particularly suitable for use in the spray-deposited layer as well as in the surrounding cast layer.
  • the contact part 3 protrudes out of the furnace in which a heater element of the illustrated type is being used.
  • FIGS. 2 and 3 show on larger scale only one end of the heater-element body in order to illustrate in which particular manner the contact layer is joined with'the body of the element.
  • the end 1% of the heater element has a symmetrical shape of circular cross section.
  • a thin aluminum layer of about 0.1 to 0.5 mm. thickness is spray-deposited at H.
  • the second layer 12. is deposited.
  • the two layers 11 and the thicker layer 12, the latter being about 2 mm. thick are shown as separate strata.
  • the original spray-deposited coating 11 is melted when the outer layer 12 is cast about the end of the heater element so that the two layers 11 and 12 become more or less of aluminum, other contact materials can also be used which have a melting point not too far remote from that of aluminum or aluminum alloys, in comparison with the melting or operating temperature of the silicon-containing material.
  • the first layer and the second layer that is, in the preferred embodiments the spray-deposited inner layer and the outer or cast layer, can also be made of respectively different contact materials so chosen that the firstdeposited layer serving for metallizing the contact end of the heater-element body, may melt at least superficially when the second, thicker layer is being cast about the inner layer, so thatany oxide coatings which may have been formed when the contact end was heated during the casting operation, are floated away.
  • the silicon-containing body of the heater element is very brittle. If a reliable electric contact engagement is to be obtained, it is not only necessary to secure a reliable electric contact between the end of the element body and a metal layer as described above, but it is also desirable to take care of a good connection of the cable, terminal or other circuit component that must be connected with the element. It has been found that if such a currentconducting component, is directly clamped to the contact end of the element, the brittle body of the element may easily be cracked or broken. Furthermore, such heater elements may have low-ohmic resistance and operate with relatively high current intensities. Under such conditions, there is the danger that the current supplying components may be subjected to considerable heating, which also requires taking care of providing a permanently reliable contact connection.
  • FIG. 5 illustrates an embodiment which satisfies the justmentioned requirements and desiderata by forming a suitable supplementation of a contact surface on a heating element produced and designed in accordance with the invention.
  • the contact end of the element body is flattened as indicated by the separation line 40 in FIG. 5.
  • the angularly related lines 40 represent respective planes that are both perpendicular to the plane of illustration.
  • the contact end of the siliconcontaining body, here denoted by 41 is flattened at the location area in accordance with these two boundary planes 40, the flattening being done by machining, for example.
  • a cable 44 of aluminum strands is equipped with a cable shoe 45 preferably consisting also of aluminum.
  • the cable shoe 45 is in good electrical contact with the bare ends of the wire strands of the cable 44.
  • the shoe 45 has the nesting shape apparent from FIG. 5 and contacts the flattened area. Consequently, when mounted together with the heater element, the shoe 45 supplements the flattened end of the element so as to form a full cylinder together therewith.
  • the cable shoe 45 is fastened together with the contact end of the element body 41 by an aluminum rive 46.
  • Another way of joining the cable shoe 45 with the element body 43 is by cold Welding or by upsetting under pressure. All of these joining methods are known and available as permanent connections as contrasted to removable screw or clamp connections.
  • An electric resistance heater element comprising a rod-shaped resistor body of refractory metal-silicide having respective terminal contacts on the respective end portions of the body, said end portions having at least one inwardly concave recess, a metallization coating of aluminum on said end portions, said metallization coating forming an intimate and oxide-free area bond with the silicide surface of said body and having a thickness of about 0.1 to about 0.5 mm., a thicker outer cast coating of aluminum integral to said metallized coating, said coatings having inwardly projecting surfaces mating with said recess for providing mechanical resistance to axial shearing forces tending to pull said coatings from said body.
  • An electric resistance heater element according to claim 1 comprising current-supply cable means permanently joined with said respective terminal contact layers.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Resistance Heating (AREA)
US559309A 1961-07-20 1966-06-21 Contact layer for a siliconcontaining material Expired - Lifetime US3307136A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
NL128272D NL128272C (ja) 1961-07-20
US559309A US3307136A (en) 1961-07-20 1966-06-21 Contact layer for a siliconcontaining material

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DES74922A DE1144418B (de) 1961-07-20 1961-07-20 Verfahren zur Herstellung einer Kontaktschicht auf einem silizium-haltigen Werkstoff
US210940A US3279042A (en) 1961-07-20 1962-07-19 Method for producing a contact layer on a silicon-containing material
US559309A US3307136A (en) 1961-07-20 1966-06-21 Contact layer for a siliconcontaining material

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US3307136A true US3307136A (en) 1967-02-28

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3397375A (en) * 1966-12-01 1968-08-13 Carborundum Co Heating element
US3969696A (en) * 1973-09-19 1976-07-13 Wolfe Denis G Refractory resistor with supporting terminal
US4058789A (en) * 1976-04-05 1977-11-15 The Carborundum Company Electrical connector
USRE29853E (en) * 1972-09-18 1978-11-28 The Tappan Company Gas igniter
US4241292A (en) * 1978-10-20 1980-12-23 Sanders Associates, Inc. Resistive heater
US20110089161A1 (en) * 2008-06-06 2011-04-21 Sandvik Materials Technology Uk Limited Electrical Resistance Heating Element

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1787749A (en) * 1927-10-04 1931-01-06 Globar Corp Electrical resistance element and process of manufacturing the same
GB365081A (en) * 1929-07-29 1932-01-15 Carborundum Co Improvements in or relating to non-metallic resistors and methods or making them
US1906963A (en) * 1930-04-28 1933-05-02 Globar Corp Impregnated silicon carbide article and the manufacture thereof
US2820534A (en) * 1954-04-22 1958-01-21 Gen Electric Hermetic ceramic-metal seal and method of making the same
US2993111A (en) * 1957-04-12 1961-07-18 Kanthal Ab Manufacture of electric resistance elements
US3100338A (en) * 1958-04-21 1963-08-13 Kaiser Aluminium Chem Corp Method of joining
US3137590A (en) * 1960-07-19 1964-06-16 Norton Co Method of making cold ends for silicon carbide resistor bars
US3252827A (en) * 1958-11-05 1966-05-24 Carborundum Co Refractory carbide bodies and method of making them

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1787749A (en) * 1927-10-04 1931-01-06 Globar Corp Electrical resistance element and process of manufacturing the same
GB365081A (en) * 1929-07-29 1932-01-15 Carborundum Co Improvements in or relating to non-metallic resistors and methods or making them
US1906963A (en) * 1930-04-28 1933-05-02 Globar Corp Impregnated silicon carbide article and the manufacture thereof
US2820534A (en) * 1954-04-22 1958-01-21 Gen Electric Hermetic ceramic-metal seal and method of making the same
US2993111A (en) * 1957-04-12 1961-07-18 Kanthal Ab Manufacture of electric resistance elements
US3100338A (en) * 1958-04-21 1963-08-13 Kaiser Aluminium Chem Corp Method of joining
US3252827A (en) * 1958-11-05 1966-05-24 Carborundum Co Refractory carbide bodies and method of making them
US3137590A (en) * 1960-07-19 1964-06-16 Norton Co Method of making cold ends for silicon carbide resistor bars

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3397375A (en) * 1966-12-01 1968-08-13 Carborundum Co Heating element
USRE29853E (en) * 1972-09-18 1978-11-28 The Tappan Company Gas igniter
US3969696A (en) * 1973-09-19 1976-07-13 Wolfe Denis G Refractory resistor with supporting terminal
US4058789A (en) * 1976-04-05 1977-11-15 The Carborundum Company Electrical connector
US4241292A (en) * 1978-10-20 1980-12-23 Sanders Associates, Inc. Resistive heater
US20110089161A1 (en) * 2008-06-06 2011-04-21 Sandvik Materials Technology Uk Limited Electrical Resistance Heating Element
US10129931B2 (en) * 2008-06-06 2018-11-13 Sandvik Materials Technology Uk Limited Electrical resistance heating element

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