GB2045737A - Electrically conductive materials for heating elements and a method of making them - Google Patents
Electrically conductive materials for heating elements and a method of making them Download PDFInfo
- Publication number
- GB2045737A GB2045737A GB8008823A GB8008823A GB2045737A GB 2045737 A GB2045737 A GB 2045737A GB 8008823 A GB8008823 A GB 8008823A GB 8008823 A GB8008823 A GB 8008823A GB 2045737 A GB2045737 A GB 2045737A
- Authority
- GB
- United Kingdom
- Prior art keywords
- refractory
- heating
- refractory part
- sliding plate
- concrete
- 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.)
- Granted
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 64
- 239000004020 conductor Substances 0.000 title claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 9
- 239000010439 graphite Substances 0.000 claims abstract description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 7
- 238000000465 moulding Methods 0.000 claims abstract description 6
- 239000004927 clay Substances 0.000 claims abstract description 4
- 239000000463 material Substances 0.000 claims description 18
- 239000000919 ceramic Substances 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 9
- 239000004033 plastic Substances 0.000 claims description 5
- 229920003023 plastic Polymers 0.000 claims description 5
- 239000011888 foil Substances 0.000 claims description 4
- 238000011065 in-situ storage Methods 0.000 claims description 4
- 239000000843 powder Substances 0.000 claims description 4
- 239000004952 Polyamide Substances 0.000 claims description 2
- 229920002647 polyamide Polymers 0.000 claims description 2
- 229920000728 polyester Polymers 0.000 claims description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 abstract 1
- 229910010271 silicon carbide Inorganic materials 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002320 enamel (paints) Substances 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B26/00—Compositions of mortars, concrete or artificial stone, containing only organic binders, e.g. polymer or resin concrete
- C04B26/02—Macromolecular compounds
- C04B26/26—Bituminous materials, e.g. tar, pitch
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/14—Closures
- B22D41/22—Closures sliding-gate type, i.e. having a fixed plate and a movable plate in sliding contact with each other for selective registry of their openings
- B22D41/28—Plates therefor
- B22D41/36—Treating the plates, e.g. lubricating, heating
-
- 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
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/001—Mass resistors
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Ceramic Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Dispersion Chemistry (AREA)
- Mechanical Engineering (AREA)
- Organic Chemistry (AREA)
- Structural Engineering (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Electromagnetism (AREA)
- Materials Engineering (AREA)
- Resistance Heating (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
- Ceramic Products (AREA)
- Sliding Valves (AREA)
Abstract
The invention relates to electrically conductive material for resistive heating elements containing between 50 and 70% by weight graphite, between 2 and 10% by weight silicon metal and about 10% binding pitch and optionally also about 10% each of anhydrous clay and silicon carbide. The invention also relates to a refractory part such as a sliding plate or a housing for a sliding plate valve having within them one or more heating elements made of such a materially moulding.
Description
SPECIFICATION
Electrically conductive materials for heating elements and a method of making them
The invention relates to electrically conductive materials for resistive heating elements based on carbon and silicon and to heating elements made from such material for embedding or moulding in refractory parts, especially those subject to wear, i.e. which come into contact with molten metal, and relates in particular to such elements for use in plates or housings of sliding gate valves. The invention also relates to a method of making refractory parts incorporating such elements.
In conventional refractory wear parts, e.g.
sliding plates for sliding gate valves on metallurgical containers of the type disclosed in
Swiss Patent No. 444390, a resistive metal wire is embedded or moulded in them to serve as a heating element. German Patent
No. 402861 discloses, by way of example, a process for the production of heating elements from silicate materials containing carbon. In this process the red-hot basic material is exposed to a stream of oxygen which oxidises the carbon on the surface to carbon dioxide and after this oxygen treatment the surface is provided with an enamel coating which renders the element airtight. In this way the carbon exposed to the oxygen in the air is saved from oxisation. German Patent No.
82455 discloses a process for the production of heating rods, in which the principal constituents are silicon and carbon, and which are obtained by heating carbon-containing members in a bed which produces silicon vapour and different parts of the member being treated are embedded in different bed compositions in order to produce different silicon contents at different points.
An object of the present invention is to provide an electrically conductive heating element which when used in refractory wear parts, particularly those made from refractory concrete, make it possible to heat these wear parts for a relatively long time to relatively high temperatures of, for example, 1500"C, so that these wear parts can be used in sliding gate valves in which the melt can be effectively prevented from freezing so that the gate valve can be used for a large number of pourings.
According to one aspect of the present invention an electrically conductive material for heating elements for embedding or moulding in refractory parts, especially those made of refractory concrete, contains between 50 and 70%, and preferably about 60% by weight graphite, e.g. natural graphite comprising crystal platelets of some tenths of a millimetre in size, between 2 and 10%, and preferably about 8% by weight slicon metal powder and between 5 and 15%, and preferably about 10% by weight binding pitch.
A heating element made from such material is not solid even at 1 500,C, but remains soft.
Thus it cannot crack, is not affected by expansion and contraction of the material in which it is set and absorbs thermal variations in length and volume. The composition can be so set that an optimum specific resistance of 0.05 Ohm cm can be achieved. The maximum current density should preferably not exceed 30 A/cm2. The heating capacity can be 1.5 to 2 kW. The heating element is refractory and thus a refractory component of the wear part. Thus the simple production of a refractory member with an electrical resistance heating capability for use at relatively high temperatures is possible, whereas this was not possible with earlier resistive metal wires.
Thermal stresses do not occur in the heated wear parts.
The conductivity of the heating element can be altered by altering the graphite content, the silicon metal dust improves the oxidation stability since it shields the graphite from oxygen, and the binding pitch, apart from its binding function, also serves to set the thermal resistance so as to maintain as uniform as possible a current density.
Preferably the material contains 5 to 20% and preferably 10% by weight anhydrous clay, e.g. windsifted plastic binding clay, which improves the workability of the material.
The material preferably also contains 5 to 20% and more preferably 10% by weight of
SiC powder which provides an optimum strength.
The invention also embraces a method of making such a material which comprises mixing together all the components with the exception of the graphite, and then adding the graphite. Such a method is found to optimise the conductivity of the material. The invention also embraces a heated refractory part, preferably made of refractory concrete, incorporating one or more heating elements made from such a material. The or each heating element may be present in grooves or openings in the refractory part in the form of an isostatically preformed element or in the form of an in-situ moulded heating element.
The or each heating element is preferably in the form of a heating rod and surrounded by an Awl203 ceramic pipe which in turn is preferably surrounded by a plastics foil of polyamide or polyester material.
The ceramic pipes serve principally to protect the heating elements against oxidation and to protect them against mechanical damage. The plastic foil serves as an additional protection against oxidation. It has been found that an optimum heating effect can be achieved when the or each heating element is in the form of a straight rod.
In one preferred embodiment the refractory part comprises a sliding plate for a sliding plate valve for a metallurgical vessel, the sliding plate having formed in it a discharge opening on each side of which extends a heating rod, the heating rods being substantially parallel and the working surface of the sliding plate being located between the two heating rods. Each heating rod is preferably spaced between 10 and 30 mm from the discharge opening and may have a diameter of between 5 and 10 mm.
In a further preferred embodiment the refractory part comprises an axially symmetrical hollow housing for a sliding plate valve for a metallurgical vessel having two or more heating rods distributed around its periphery and extending substantially in the axial direction.
The heating rods preferably extend at each end between 20 and 50 mm beyond the edge of the refractory part. This enables the electrical connections to be made remote from the refractory part. The or each heating rod preferably has at each end an electrical connection which extends over an area of between 1 and 5 cm2 on its projecting surface. Such a construction prevents overheating of the electrical connections.
The refractory part may be impregnated with tar and may be burnt before its first use.
The invention further embraces a method of production of such a refractory part. Thus according to a further aspect of the invention such a method comprises introducing into a mould a quantity of chemically or hydraulically setting refractory concrete, vibrating the concrete and forming a groove or opening in it into which the electrically conductive material is introduced to constitute a heating rod either by in-situ moulding or in the form of a preformed heating rod, and then adding a further quantity of refractory concrete which is vibrated to compress it and the concrete is finally hardened. According to a still further aspect of the invention such a method comprises inserting into a mould one or more preformed heating rods of the conducting material and then inserting chemically or hydraulically setting refractory concrete and then vibrating, compressing and hardening it.
The refractory concrete may be based on tabular alumina with cement. The or each heating element may be within an Awl203 ceramic sleeve which in turn may be within a plastics foil. After hardening the refractory part may be impregnated with tar and/or burnt before use.
Further features and details of the invention will be apparent from the following description of certain specific embodiments which is given by way of example with reference to the accompanying drawings in which:
Figure 1 is a diagrammatic horizontal sectional view of a sliding plate for a sliding gate valve;
Figure 2 is a diagrammatic lateral sectionalview of a housing with heating elements according to the present invention and
Figure 3a and 3b shown to alternative embodiments of the current connections to the heating elements.
The elongate sliding plate 4 shown in Fig.
1 has two straight heating rods 2 formed of a mixture of components as described above which are parallel to the longitudinal edges of the plate and to each other and which are accommodated in aluminium oxide (Al203) ceramic pipes 1, the ends of which project beyond the ends of the sliding plate 4. Between the heating rods 2 are the discharge opening 6 through which, in use, molten metal flows and the working surface 9 of the sliding plate 4. At each end of the ceramic pipes 1 there is an opening through which a current supply lead 5 is led to respective capshaped electrical connection 3 which are let into the heating rods 2.
Fig. 2 shows a frusto-conical sliding gate valve housing 7 having within it a centrally disposed frusto-conical passage which is adapted to be subjected to wear and whir:1 has within it four heating rods 2 extending substantially in the axial direction, i.e. only slightly inclined to the axis of the housing at an angle between that of the inner surface of the housing and that of its outer surface.
These heating rods 2 are straight and are retained in ceramic pipes 1 the ends of which project from the housing 7 where the current is supplied in a manner similar to that shown in Fig. 1. In the illustrated example four heating rods 2 offset by 90 are arranged in the wall of the housing 7.
Fig. 3a shows in detail the arrangement of the electrical connection 3 to the current supply 5 which has already been described in connection with Fig. 1.
Fig. 3b shows in detail an alternative current connection 3 of a heating rod 2 which is inserted in a groove 8 without a special ceramic pipe 1.
Claims (21)
1. Electrically conductive material for heating elements for embedding or moulding in refractory parts containing between 50 and 70% by weight graphite, between 2 and 10% by weight silicon metal powder and between 5 and 15% by weight of binding pitch.
2. A material is claimed in Claim 1 containing between 5 and 20% by weight anhydrous clay.
3. A material as claimed in Claim 1 or
Claim 2 containing between 5 and 20% by weight SiC powder.
4. A method of making a material as claimed in any one of Claims 1 to 3 which comprises mixing together all the components with the exception of the graphite, and then adding the graphite.
5. A heated refractory part having in it one or more electrical heating elements made from a material as claimed in any one of
Claims 1 to 3.
6. A refractory part as claimed in Claim 5 which is made of refractory concrete.
7. A refractory part as claimed in Claim 5 or Claim 6 in which the or each heating element is present in grooves or openings in it in the form of an isostatically pressed preformed heating element.
8. A refractory part as claimed in Claim 5 or Claim 6 in which the or each heating element is moulded in situ in grooves or openings in it.
9. A refractory part as claimed in any one of Claims 5 to 8 in which the or each heating element is in the form of a heating rod and surrounded by an Awl203 ceramic pipe.
10. A refractory part as claimed in Claim 9 in which the or each ceramic pipe is surrounded by a plastics foil of polyamide or polyester.
11. A refractory part as claimed in any one of Claims 5 to 10 comprising a sliding plate for a sliding plate valve for a metallurgical vessel, the sliding plate having formed in it a discharge opening on each side of which extends a heating rod, the heating rods being substantially parallel and the working surface of the sliding plate being located between the two heating rods.
1 2. A refractory part as claimed in Claim 11 in which each heating rod is spaced between 10 and 30 mm from the discharge opening.
1 3. A refractory part as claimed in any one of Claims 9 to 1 2 in which the or each heating rod has a diameter of between 5 and 10 mm.
14. A refractory part as claimed in any one of claims 5 to 10 which comprises an axially symmetrical hollow housing for a sliding plate valve for a metallurgical vessel having two or more heating rods distributed around its periphery and extending substantially in the axial direction.
1 5. A refractory part as claimed in any one of Claims 9 to 14 in which the heating rods extend at each end between 20 and 50 mm beyond its edge.
16. A refractory part as claimed in Claim 1 5 in which the or each heating rod has at each end an electrical connection which extends over an area of between land 5 cm2 on its projecting surface.
1 7. A refractory part as claimed in any one of Claims 5 to 1 6 which is impregnated with tar.
1 8. A refractory part as claimed in any one of Claims 5 to 1 7 which is burnt before its first use.
1 9. A method of production of a refractory part as claimed in any one of Claims 5 to 1 8 comprising introducing into a mould a quantity of chemically or hydraulically setting refractory concrete, vibrating the concrete and forming a groove or opening in it into which a material as claimed in any one of Claims 1 to 3 is introduced to constitute a heating rod either by in-situ moulding or in the form of a preformed heating rod, and then adding a further quantity of refractory concrete which is vibrated to compress it and the concrete is finally hardened.
20. A method of production of a refractory part as claimed in any one of Claims 5 to 18 comprising inserting into a mould one or more preformed heating rods of a material as claimed in any one of Claims 1 to 3 and then inserting chemically or hydraulically setting refractory concrete and then vibrating, compressing and hardening it.
21. A refractory part having in it one or more heating elements of electrically conductive material substantially as specifically herein described with reference to Fig. 1 or
Fig. 2 in combination with either of Figs. 3a or 3b.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792910151 DE2910151A1 (en) | 1979-03-15 | 1979-03-15 | ELECTRIC HEATING CONDUCTOR, YOUR PREPARATION, YOUR USE IN A HEATABLE WEARING PART AND A METHOD FOR PRODUCING SUCH WEARING PARTS WITH THE HEATING CONDUCTOR |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2045737A true GB2045737A (en) | 1980-11-05 |
| GB2045737B GB2045737B (en) | 1983-03-09 |
Family
ID=6065449
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8008823A Expired GB2045737B (en) | 1979-03-15 | 1980-03-14 | Electrically conductive materials for heating elements and a method of making them |
Country Status (7)
| Country | Link |
|---|---|
| BE (1) | BE881259A (en) |
| CA (1) | CA1144361A (en) |
| DE (1) | DE2910151A1 (en) |
| ES (1) | ES488798A1 (en) |
| FR (1) | FR2451694A1 (en) |
| GB (1) | GB2045737B (en) |
| IT (1) | IT1125907B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1208930A1 (en) * | 2000-11-23 | 2002-05-29 | SMS Demag AG | Sliding closure for metallurgical vessels |
| EP1344988A2 (en) | 2002-03-12 | 2003-09-17 | Sgl Carbon Ag | Carbonaceous molded body for room heating |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3109941A1 (en) * | 1981-03-14 | 1982-09-23 | Carl G.O. Dipl.-Ing. 7752 Insel Reichenau Korn | Process for recording and reproducing signals at very high frequency on magnetic tapes |
| DE3930866C1 (en) * | 1989-09-15 | 1991-02-28 | Didier-Werke Ag, 6200 Wiesbaden, De |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE402861C (en) * | 1923-06-15 | 1924-09-19 | Drahtlose Heiz U Widerstands K | Process for the production of heating elements from carbon-containing silicate mass |
| DE457074C (en) * | 1925-02-28 | 1928-03-08 | Studien Ges Fuer Wirtschaft Un | Silicate-containing electrical heating conductor |
| DE482455C (en) * | 1928-01-28 | 1929-09-14 | Siemens Planiawerke A G Fuer K | Process for the production of heating rods which contain silicon and carbon as main components |
| DE1019019B (en) * | 1951-05-29 | 1957-11-07 | Hermann Knipping | Electric heating element |
| US3352549A (en) * | 1964-10-29 | 1967-11-14 | Blaw Knox Co | Composite carbonaceous members for furnace rolls and other high temperature members |
| CH444390A (en) * | 1966-08-30 | 1967-09-30 | Interstop Ag | Method for casting metals from a casting vessel with a slide closure |
| DE1910707C3 (en) * | 1969-03-03 | 1982-12-16 | 6200 Wiesbaden Didier-Werke Ag | Bottom slide closure for the pouring opening of vessels containing molten metal and a method for operating the same |
| CH545249A (en) * | 1971-04-15 | 1973-12-15 | Lonza Ag | Process for making an isotropic graphite material |
| DE2401784A1 (en) * | 1974-01-15 | 1975-07-24 | Sibirsk Nii Energetiki | Electrically conducting material - for resistors and building components made from mixt of cement, graphite and a filler |
| IT1072241B (en) * | 1976-12-17 | 1985-04-10 | Cselt Centro Studi Lab Telecom | ITFORNACE ELECTRIC MOLD RESISTANT LA WITH POWDER GRAPHITE RESISTIVE ELEMENT |
| DE2709462C2 (en) * | 1977-03-04 | 1979-01-11 | Martin & Pagenstecher Gmbh, 5000 Koeln | Slide closure for containers containing molten metal |
-
1979
- 1979-03-15 DE DE19792910151 patent/DE2910151A1/en not_active Withdrawn
- 1979-12-04 IT IT27865/79A patent/IT1125907B/en active
- 1979-12-27 FR FR7931792A patent/FR2451694A1/en active Pending
-
1980
- 1980-01-21 BE BE0/199049A patent/BE881259A/en not_active IP Right Cessation
- 1980-01-22 CA CA000344139A patent/CA1144361A/en not_active Expired
- 1980-02-21 ES ES488798A patent/ES488798A1/en not_active Expired
- 1980-03-14 GB GB8008823A patent/GB2045737B/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1208930A1 (en) * | 2000-11-23 | 2002-05-29 | SMS Demag AG | Sliding closure for metallurgical vessels |
| EP1344988A2 (en) | 2002-03-12 | 2003-09-17 | Sgl Carbon Ag | Carbonaceous molded body for room heating |
Also Published As
| Publication number | Publication date |
|---|---|
| BE881259A (en) | 1980-05-16 |
| DE2910151A1 (en) | 1980-10-02 |
| FR2451694A1 (en) | 1980-10-10 |
| CA1144361A (en) | 1983-04-12 |
| ES488798A1 (en) | 1980-09-16 |
| GB2045737B (en) | 1983-03-09 |
| IT7927865A0 (en) | 1979-12-04 |
| IT1125907B (en) | 1986-05-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |