GB2285058A - Alloy for radiant electric heater - Google Patents
Alloy for radiant electric heater Download PDFInfo
- Publication number
- GB2285058A GB2285058A GB9326417A GB9326417A GB2285058A GB 2285058 A GB2285058 A GB 2285058A GB 9326417 A GB9326417 A GB 9326417A GB 9326417 A GB9326417 A GB 9326417A GB 2285058 A GB2285058 A GB 2285058A
- Authority
- GB
- United Kingdom
- Prior art keywords
- percent
- weight
- equal
- electric heater
- radiant electric
- 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
- 239000000956 alloy Substances 0.000 title claims abstract description 11
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 15
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 14
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims abstract description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000012772 electrical insulation material Substances 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 8
- 229910052747 lanthanoid Inorganic materials 0.000 claims abstract description 8
- 150000002602 lanthanoids Chemical class 0.000 claims abstract description 8
- 239000004411 aluminium Substances 0.000 claims abstract description 7
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 7
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 6
- 239000011651 chromium Substances 0.000 claims abstract description 6
- 229910052742 iron Inorganic materials 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims abstract description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 4
- 239000010703 silicon Substances 0.000 claims abstract description 4
- 239000010936 titanium Substances 0.000 claims abstract description 4
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 4
- 238000009413 insulation Methods 0.000 claims description 2
- 239000012774 insulation material Substances 0.000 description 8
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 3
- 239000000470 constituent Substances 0.000 description 3
- 238000010411 cooking Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 239000012229 microporous material Substances 0.000 description 2
- 239000003605 opacifier Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000004964 aerogel Substances 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- UPHIPHFJVNKLMR-UHFFFAOYSA-N chromium iron Chemical compound [Cr].[Fe] UPHIPHFJVNKLMR-UHFFFAOYSA-N 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000007792 gaseous phase Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000002241 glass-ceramic Substances 0.000 description 1
- -1 lanthanum and cerium Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 239000011236 particulate material Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001698 pyrogenic effect Effects 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- 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
-
- 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
- H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
- H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
- H05B3/748—Resistive heating elements, i.e. heating elements exposed to the air, e.g. coil wire heater
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Resistance Heating (AREA)
Abstract
A radiant electric heater comprises a base (2) of thermal and electrical insulation material supporting an electrical heating element (4) which may be in the form of a strip or ribbon (5) and comprises an alloy having the following composition: Chromium 14 to 27 percent by weight Aluminium 3.5 to 6.5 percent by weight Silicon less than or equal to 1.0 percent by weight Carbon less than or equal to 0.02 percent by weight Lanthanum between 0.05 and 0.20 percent by weight Cerium less than or equal to 0.01 percent by weight the remainder being iron and impurities. Titanium is optionally present in an amount greater than or equal to five times the content of carbon and up to a maximum of 0.10 percent by weight. One or more lanthanides other than lanthanum and cerium maybe further optionally present in an amount greater than or equal to 0.001 percent by weight and less than 0.03 percent by weight, the overall lanthanide content, including lanthanum and cerium being less than or equal to 0.20 percent by weight. <IMAGE>
Description
Radiant Electric Heater
This invention relates to a radiant electric heater, particularly for use with a smooth top glass cerarnic cooking appliance.
More particularly the invention relates to a radiant electric heater comprising a base of thermal and electrical insulation material supporting an electrical heating element comprising an alloy with iron, chromium and aluminium as major constituents, the element being adapted whereby improved resistance to thermal oxidation and hence longer life is achieved when connected to an electrical power source and electrically self-heated to radiance.
a mvention is particularly advantageous with an electrical heating element in the form of a thin strip or ribbon, for example of thickness from 20 to 200 microns, supported on edge on the base of insulation material. With such a heating element, there has been a problem of achieving a satisfactory operating life as a result of excessive thermal oxidation or physical deformation thereof when in operation.
According to the invention there is provided a radiant electric heater comprising a base of thermal and electrical insulation material supporting an electrical heating element adapted to be connected to an electrical suppl; the element comprising an alloy having the following composition:
Chromium 14 to 27 percent by weight
Aluminium 3.5 to 6.5 percent by weight
Silicon less than or equal to 1.0 percent by weight
Carbon less than or equal to 0.02 percent by weight
Lanthanum between 0.05 and 0.20 percent by weight
Cerium less than or equal to 0.01 percent by weight the remainder being iron and impurities; there being optionally present titanium in an amount greater than or equal to five times the content of carbon and up to a maximum of 0.10 percent by weight; there being further optionally present one or more lanthanides other than lanthanum and cerium in an amount greater than or equal to 0.001 percent by weight and less than 0.03 percent by weight, the overall lanthanide content, including lanthanum and cerium being less than or equal to 0.20 percent by weight.
The element may be in the form of a thin elongate strip or ribbon, supported on edge on the base of thermal and electrical insulation material.
The strip or ribbon may suitablv have a thickness of from 20 to 200 microns, preferably from 50 to 100 microns.
The strip or ribbon may be of corrugated form.
The base may comprise microporous thermal and electrical insulation material which ma! be provided as a compacted layer in a supporting dish, suitably of metal.
The term 'microporous' is used herein to identify porous or cellular materials in which the ultimate size of the cells or voids is less than the mean free path of an air molecule at NTP, i.e.
of the order of 100 nm or smaller. A material which is microporous in this sense will exhibit very low transfer of heat by air conduction (that is collisions between air molecules). Such microporous materials include aerogel, which is a gel in which the liquid phase has been replaced by a gaseous phase in such a way as to avoid the shrinkage which would occur if the gel were dried directly from a liquid. A substantially identical structure can be obtained by controlled precipitation from solution, the temperature and pH being controlled during precipitation to obtain an open lattice precipitate.Other equivalent open lattice structures include pyrogenic (fumed) and electro-thermal types in which a substantial proportion of the particles have an ultimate particle size less than 100 nm. Any of these particulate materials, based for example on silica, alumina or other metal oxides, may be used to prepare a composition which is microporous as defined above.
The microporous insulation typically comprises a dry particulate microporous material as defined hereinabove mixed with a high temperature ceramic or vitreous fibre reinforcement, titanium dioxide opacifier and, for high-temperature use, a small quantity of alumina powder to reduce high temperature shrinkage. Such insulation material is described in GB-A-1 580 909.
A terminal connector may be provided, secured to the dish, for electrical connection of the element to an electrical supply.
The radiant electric heater of the present invention, which includes a heating element comprising an alloy in which iron chromium and aluminium are main constituents but which has a carefully controlled content of lanthanum in the range of 0.05 to 0.20 percent by weight and the minimum possible content of cerium, exhibits excellent oxidation resistance of its heating element when in operation and good life expectancy even when the element is in the fonn of a thin strip or ribbon.
The invention is now described by way of example with reference to the accompanying drawings in which:
Figure 1 is a plan view of a radiant electric heater according to the invention;
Figure 2 is a cross-sectional view of the radiant heater of Figure 1; and
Figure 3 is a perspective view of the heating element in the radiant heater of Figures 1 and 2.
A radiant electric heater is constructed comprising a metal dish 1 containing a base layer 2 of thermal and electrical insulation material. The insulation material is preferably microporous thermal and electrical insulation material.
Suitable microporous thermal and electrical insulation materials are well-known in the art, for example as described in GB-A-1 580 909, a typical composition being:
Microporous pyrotenic silica 49 to 97 percent by weight
Ceramic fibre reinforcement 0.5 to 20 percent by weight
Opacifier 2 to 50 percent by weight
Alumina up to 12 percent by weight
The proportion of alumina is preferably in the range from 0.5 to 2 percent by weight.
A heating element 4 is provided from an elongate strip or ribbon 5 of a metal allow having as main constituents iron, chromium and aluminium and between 0.05 and 0.20 percent by weight of lanthanum. Little or no cerium is contained in the alloy since this material increases thermal oxidation of the element when electrically self-heated to radiance when in operation in the heater. In practice, the alloy should contain not more than 0.01 percent by weight of cerium.
The alloy of the strip or ribbon 5 comprises:
Chromium 14 - 27 percent by weight
Aluminium 3.5 - 6.5 percent by weight
Silicon not more than 1.0 percent by weight
Carbon not more than 0.02 percent by weight
Lanthanum between 0.05 and 0.20 percent by weight
Cerium not more than 0.01 percent by weight the remainder being iron and impurities.
If desired, titanium may be included in a content greater than or equal to five times the content of carbon in the alloy, but less than or equal to 0.10 percent by weight.
One or more lanthanides other than lanthanum or cerium may optionally be provided in the alloy in a content greater than or equal to 0.001 percent by weight and less than 0.03 percent by weight and such that the overall content of the lanthanide, including lanthanum and cerium,
Is less than or equal to 0.20 percent by weight.
The strip or ribbon 5 is formed of a thickness between about 20 and 200 microns and preferably between about 50 and 100 microns. A typical height h of the strip 5 is from 3 to 6 mm. The strip 5 is provided of corrugated form and is bent into the desired shape for the heating element as shown in Figure 3. The resulting heating element 4 is secured to the base 2 of insulation material suitably by embedding it to part of its height in the base 2. If desired, the strip 5 may be profiled along that edge thereof which is embedded in the insulation material, for example by providing dournwardly-extending integral spaced-apart tabs (not shown) which are embedded in the insulation material of the base 2.
A terminal connector 6 is provided for electrically connecting the heating element 4 to an electrical power supply, for operation thereof.
Against the side of the dish 1 is located a peripheral wall 3 of thermal insulation material, such as a ceramic fibre material made from aluminosilicate fibres or alternatively microporous insulation material.
A well-known form of thermal cut-out device 7 is provided, extending over the heating element 4, to switch off the heating element in the event of over-heating when the heater is installed and operating in a cooking appliance having a glass-ceramic cooking surface.
The resulting heater when connected to an electrical power supply operates with the heating element 4 exhibiting radiance and with operating temperatures of 900"C to 1000us being achievable without serious degradation of the element by thermal oxidation.
Claims (9)
1. A radiant electric heater comprising a base of thermal and electrical insulation material
supporting an electrical heating element adapted to be connected to an electrical supply, the
element comprising an alloy having the following composition:
Chromium 14 to 27 percent by weight
Aluminium 3.5 to 6.5 percent by weight
Silicon less than or equal to 1.0 percent by weight
Carbon less than or equal to 0.02 percent by weight
Lanthanum between 0.05 and 0.20 percent by weight
Cerium less than or equal to 0.01 percent by weight
the remainder being iron and impurities;
there being optionally present titanium in an amount greater than or equal to five times the
content of carbon and up to a maximum of 0.10 percent by weight;;
there being further optionally present one or more lanthanides other than lanthanum and
cerium in an amount greater than or equal to 0.001 percent by weight and less than 0.03
percent by weight, the overall lanthanide content, including lanthanum and cerium being
less than or equal to 0.20 percent by weight.
2. A radiant electric heater according to claim 1, in which the element is in the form of a thin
elongate strip or ribbon, supported on edge on the base of thermal and electrical insulation
material.
3. A radiant electric heater according to claim 2, in which the strip or ribbon has a thickness
of from 20 to 200 microns.
4. A radiant electric heater according to claim 3, in which the strip or ribbon has a thickness
of from 50 to 100 microns.
5. A radiant electric heater according to ant one of claims 2 to 4, in which the strip or ribbon
is of corrugated form.
6. A radiant electric heater according to any one of the preceding claims, in which the base
comprises microporous thermal and electrical insulation material.
7. A radiant electric heater according to claim 6, in which the microporous insulation materi21 is provided as a compacted layer in a supporting dish.
8. A radiant electric heater according to claim 7, in which a terminal connector is provided,
secured to the dish, for electrical connection of the element to an electrical supply.
9. A radiant electric heater constructed and arranged substantially as hereinbefore described
with reference to the accompanying drawings.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9326417A GB2285058B (en) | 1993-12-24 | 1993-12-24 | Radiant Electric Heater |
| DE9419922U DE9419922U1 (en) | 1993-12-24 | 1994-12-13 | Electric radiant heater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9326417A GB2285058B (en) | 1993-12-24 | 1993-12-24 | Radiant Electric Heater |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9326417D0 GB9326417D0 (en) | 1994-02-23 |
| GB2285058A true GB2285058A (en) | 1995-06-28 |
| GB2285058B GB2285058B (en) | 1997-01-08 |
Family
ID=10747191
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9326417A Expired - Fee Related GB2285058B (en) | 1993-12-24 | 1993-12-24 | Radiant Electric Heater |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE9419922U1 (en) |
| GB (1) | GB2285058B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19522798A1 (en) * | 1995-06-23 | 1997-01-02 | Ego Elektro Blanc & Fischer | Process for producing a radiant heater and radiant heater |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB429492A (en) * | 1934-01-18 | 1935-05-30 | Heraeus Vacuumschmelze Ag | Improvements in and relating to the production of heat-resistant alloys |
| GB2019886A (en) * | 1978-04-28 | 1979-11-07 | Atomic Energy Authority Uk | Oxidation-resistant fe - cr - al - y - si alloys |
| GB2070642A (en) * | 1980-02-28 | 1981-09-09 | Firth Brown Ltd | Ferritic iron-aluminium- chromium alloys |
| US4904540A (en) * | 1986-04-21 | 1990-02-27 | Kawasaki Steel Corp. | Fe-Cr-Al stainless steel having high oxidation resistance and spalling resistance and Fe-Cr-Al steel for catalyst substrate of catalytic converter |
| EP0387670A1 (en) * | 1989-03-16 | 1990-09-19 | Krupp VDM GmbH | Ferritic-steel alloy |
| US5045404A (en) * | 1989-03-27 | 1991-09-03 | Nippon Steel Corporation | Heat-resistant stainless steel foil for catalyst-carrier of combustion exhaust gas purifiers |
-
1993
- 1993-12-24 GB GB9326417A patent/GB2285058B/en not_active Expired - Fee Related
-
1994
- 1994-12-13 DE DE9419922U patent/DE9419922U1/en not_active Expired - Lifetime
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB429492A (en) * | 1934-01-18 | 1935-05-30 | Heraeus Vacuumschmelze Ag | Improvements in and relating to the production of heat-resistant alloys |
| GB2019886A (en) * | 1978-04-28 | 1979-11-07 | Atomic Energy Authority Uk | Oxidation-resistant fe - cr - al - y - si alloys |
| GB2070642A (en) * | 1980-02-28 | 1981-09-09 | Firth Brown Ltd | Ferritic iron-aluminium- chromium alloys |
| US4904540A (en) * | 1986-04-21 | 1990-02-27 | Kawasaki Steel Corp. | Fe-Cr-Al stainless steel having high oxidation resistance and spalling resistance and Fe-Cr-Al steel for catalyst substrate of catalytic converter |
| EP0387670A1 (en) * | 1989-03-16 | 1990-09-19 | Krupp VDM GmbH | Ferritic-steel alloy |
| US5045404A (en) * | 1989-03-27 | 1991-09-03 | Nippon Steel Corporation | Heat-resistant stainless steel foil for catalyst-carrier of combustion exhaust gas purifiers |
Also Published As
| Publication number | Publication date |
|---|---|
| DE9419922U1 (en) | 1995-02-02 |
| GB9326417D0 (en) | 1994-02-23 |
| GB2285058B (en) | 1997-01-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20051224 |