GB2327429A - Method of Heat Treating an Alloy Material. - Google Patents
Method of Heat Treating an Alloy Material. Download PDFInfo
- Publication number
- GB2327429A GB2327429A GB9714934A GB9714934A GB2327429A GB 2327429 A GB2327429 A GB 2327429A GB 9714934 A GB9714934 A GB 9714934A GB 9714934 A GB9714934 A GB 9714934A GB 2327429 A GB2327429 A GB 2327429A
- Authority
- GB
- United Kingdom
- Prior art keywords
- group
- ribbon
- alloy
- undulations
- percent
- 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.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/10—Oxidising
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/02—Pretreatment of the material to be coated
Abstract
In a method of heat treating an alloy material in the form of a ribbon in a treatment atmosphere, the ribbon (1) is wound into reel form for treating. Prior to winding, the ribbon is formed with undulations along its length. In order to reduce or minimise risk of nesting of adjacent turns of wound ribbon it is arranged for the ratio of the length (L 1 ) of the ribbon before provision of undulations to the length (L 2 ) of the ribbon after provision of undulations to be front 1.001 to 1.1, preferably of the order of 1.01, the undulations having a pitch (P) of from 0.1 mm to 4 mm, preferably of the order of 1.0 mm.
Description
Method of Heat Treating an Allov Material
This invention concerns a method of heat treating an alloy material in the form of a ribbon in a treatment atmosphere. More particularly. but not exclusively. the invention concerns a method of heat treating an alloy in the foml of a ribbon of electrical resistance material to produce an electrical resistance heating element.
In WO 95/28818. a method of manufacturing an electrical resistance heating means is described. An electrical resistance material is provided comprising an alloy having the following composition in weight percent:
Group A: aluminium 3-8 yttrium. zirconium. hafnium and/or one or more rare earth elements 0 - 0.45
Group B: chromium 12 - 30 iron and/or nickel and/or cobalt balance
The electrical resistance material is heat treated in a heating stage consisting of the steps of: a) providing an atmosphere around the electrical resistance material. the potential for
oxidation of the atmosphere being such as to permit oxidation of the constituent(s) from
Group A and to inhibit oxidation of the constituents from Group B: and b) heating the electrical resistance material in the atmosphere to a temperature in the range
from 8000C to a temperature below the melting point of the alloy so as to oxidise the
constituents of Group A at the surface of the alloy whereby to form a surface layer
consisting essentially of continuous unified oxide of the constituent(s) of Group A. The
heat treatment is effected in a single stage in an atmosphere consisting of water vapour.
As a result of such heat treatment an electrical resistance heating element is provided which, when operated in a radiant electric heater, such as in a cooking appliance, exhibits a considerably longer life, particularly under conditions of temperature cycling, than an untreated heating element.
The aforementioned heat treatment is particularly advantageous in the manufacture of heating elements in the form of thin allot ribbons.
In the examples described in WO 95/28818, a length of ribbon was electrically self-heated in a water vapour atmosphere in a quartz tube. Such a technique is suitable for treating relatively short lengths of ribbon, but is inappropriate for production of treated ribbon in large volume.
It was considered that this problem could be overcome by winding ribbon into reel form and placing it in a fumace heated to the required temperature and containing the necessary water vapour treatment atmosphere. However with this technique, adequate penetration of the water vapour between the windings of the ribbon does not occur and furthermore there is a tendency for adhesion to occur between the windings of the ribbon.
In the manufacture of catalytic converters, for use in motor vehicle engine exhaust systems, it is known to provide a corrugated alloy ribbon wound into reel form. The resulting wound ribbon is then subject to heat treatment in a treatment atmosphere. When corrugated ribbons are wound into reel form, there is a tendency for the corrugations of one or more adjacent turns to nest with one another. This is unacceptable since contact with treatment atmospheres is thereby impaired and efficient passage of exhaust gasses through the converter is inhibited.
Consequently it is known to provide a flat, that is uncorrugated, interleaving ribbon between adjacent turns of corrugated ribbon. Such an interleaving ribbon prevents nesting of the corrugations in the wound ribbon and allows free access of treatment atmospheres and passage of exhaust gases. However, while it can be justified for permanent use in a catalytic converter, its temporary use to allow efficient heat treatment of an alloy ribbon in a treatment atmosphere would be inconvenient and expensive.
It is an object of the present invention to overcome or minimise this problem.
The present invention provides a method of heat treating an alloy material in the form of a ribbon in a treatment atmosphere, in which the ribbon is wound into reel form for treating and wherein prior to winding, the ribbon is formed with undulations along its length such that the ratio of the length of the ribbon before provision of undulations to the length of the ribbon after provision of undulations is from 1.001 to 1.1, preferably from 1.005 to 1.05 and more preferably of the order of 1.01, the undulations having a pitch of from 0.1 mm to 4 mm, preferably of from 0.5 mm to 1.5 mm and more preferably of the order of 1.0 mm.
As a result of forming the undulations with the specified dimensions, risk of nesting of adjacent turns of undulated ribbon is reduced or minimised whilst access of the treatment atmosphere to the ribbon between turns is facilitated. Risk of adhesion between adjacent tums of ribbon is also reduced or minimised.
The heat treating of the ribbon of alloy material in the treatment atmosphere may be such as to form on the surface thereof an oxide layer.
The alloy material may be in the form of an electrical resistance material having the following composition in weight percent:
Group A: aluminium 3-8 yttrium, zirconium, hafnium and/or one or more rare earth elements 0 - 0.45
Group B: chromium 12 - 30 iron and/or nickel and/or cobalt balance
Such electrical resistance material may be heated in a heating stage consisting of the steps of: a) providing an atmosphere around the electrical resistance material, the potential for
oxidation of the atmosphere being such as to permit oxidation of the constituent(s) from
Group A and to inhibit oxidation of the constituents from Group B and b) heating the electrical resistance material in the atmosphere to a temperature in the range
from 800"C to a temperature below the melting point of the alloy so as to oxidise the
constituents of Group A at the surface of the alloy whereby to form a surface layer
consisting essentially of continuous unified oxide of the constituent(s) of Group A.
The heat treatment may be effected in an atmosphere comprising water vapour and may be effected in a single stage.
The heating may be effected at a temperature from 800"C to 1475"C, preferably from 8000C to about 1300"C.
The alloy may have the following composition in weight percent:
Group A: aluminium 3-8
preferably 4.5 - 6
Group B: chromium 12-30
preferably 19 - 23 iron and/or nickel and/or cobalt balance
Alternatively, the alloy may have the following composition in weight percent:
Group A: aluminium 3-8
preferably 4.5 - 6 yttrium, zirconium. hafnium and/or one or more rare earth elements 0.01 - 0.45
preferably 0.025 - 0.4
Group B: chromium 12 - 30
preferably 19 - 23 iron and/or nickel and/or cobalt balance
The one or more rare earth elements may comprise lanthanum and/or cerium, preferably lanthanum. Where the rare earth elements comprise lanthanum and cerium the combined content of these elements in the alloy may be in the range from 0.025 to 0.07 percent by weight. Preferably the lanthanum content is in the range from 0.005 to 0.02 percent by weight and the cerium content is in the range from 0.02 to 0.05 percent by weight. Where the rare earth element comprises lanthanum, the lanthanum content of the alloy may be in the range from 0.06 to 0.15 percent by weight.
Where zirconium is present, the zirconium content of the alloy may be in the range from 0.1 to 0.4 percent by weight.
The surface oxide layer may consist substantially of aluminium oxide.
The method of the invention is especially advantageous for manufacturing an electrical resistance heating means, particularly, but not exclusively. for use in a heater for a cooking appliance.
The invention is now described bv way of example with reference to the accompanying drawings in which:
Figure 1 is a side view of a ribbon of alloy material.
Figure 2 is a side view of the ribbon of Figure 1 formed with undulations along its length; and
Figure 3 is a side view of the ribbon of Figure 2 wound into reel form.
Referring to Figure 1, an alloy material in the form of a ribbon I is required to be heat treated in a treatment atmosphere. The alloy material may, for example, be an electrical resistance material for an electrical resistance heating means, such as a radiant heating element in a heater for use in a cooking appliance. The alloy and the heat treatment thereof may be as described in
WO 95/28818. For example the ribbon 1 may have a thickness of between 20 and 200 microns and may comprise a resistance element made of an alloy having the following composition in weight percent: aluminium 4.5 - 6 lanthanum 0.06-0.15 chromium 19 - 22 iron balance
A substantial length of the ribbon 1 is required to be heated in the treatment atmosphere which,
for the particular exemplified alloy composition, comprises water vapour. inside a furnace 2, at
a temperature of between about 800"C and 1 4750C and preferably about 900 C.
To enable the maximum length of ribbon 1 to be accommodated in a furnace of compact dimensions, the ribbon 1 is wound into reel form. However. in order to ensure optimum exposure of the ribbon 1 to the treatment atmosphere the ribbon, before winding into reel form, is formed with undulations along its length as shown in Figure 2. The dimensional parameters of the undulations are selected such that nesting of undulations of adjacent turns is minimised upon subsequent winding of the ribbon into reel form onto a reel 3 as shown in Figure 3, permitting maximum penetration of the treatment atmosphere between adjacent turns, but also ensuring good compactness and mechanical stability of the wound rcel.
The undulations are formed such that the ratio of the length L1 of the ribbon before provision of undulations to the length L2 of the ribbon after provision of undulations is from 1.001 to I 1 I .
preferably from 1.005 to 1.05 and more preferably of the order of 1.01. The pitch P of the undulations is from 0.1 to 4 mm, preferably from 0.5 to 1.5 mm and more preferably of the order of 1.0 mm.
A typical value for the ainplitude A of the undulations is about 0.15 mm.
During the treatment of the wound ribbon 1 in the treatment atmosphere of water vapour a continuous unified protective oxide layer, substantially comprising aluminium oxide, is formed on the surface of the ribbon and risk of adhesion between adjacent turns of the wound ribbon is minimised.
After treatment, the ribbon may be unwound from its reel form and further processed to produce a heating element. Such further processing may include corrugating the ribbon for use in a radiant heater, as described in WO 95/288818. During the corrugating process, the undulations formed for the heat treatment are substantially eliminated.
Claims (27)
1. A method of heat treating an alloy material in the form of a ribbon in a treatment
atmosphere, in which the ribbon is wound into reel form for treating and wherein prior to winding, the ribbon is formed with undulations along its length, such that the ratio of the
length of the ribbon before provision of undulations to the length of the ribbon after
provision of undulations is from 1.001 to 1.1. the undulations having a pitch of from 0.1
mm to 4 mm.
2. A method according to claim 1, in which the ratio is from 1.005 to 1.05.
3. A method according to claim 2, in which the ratio is of the order of 1.0 1.
4. A method according to claim 1, 2 or 3, in which the undulations have a pitch of from 0.5
my to 1.5 mm.
5. A method according to claim 4, in which the undulations have a pitch of the order of 1.0
mm.
6. A method according to any one of the preceding claims, in which the heat treating of the
ribbon of alloy material in the treatment atmosphere is such as to form on the surface
thereof an oxide layer.
7. A method according to claim 6, in which the alloy material is in the fonn of an electrical
resistance material having the following composition in weight percent:
Group A:
aluminium 3 -
8
yttrium, zirconium, hafnium
and/or one or more rare earth elements 0 - 0.45
Group B:
chromium 12 - 30
iron and/or nickel and/or cobalt balance 8. A method according to claim 7, in which the resistance material is heated in a heating stage
consisting of the steps of:
a) providing an atmosphere around the electrical resistance material, the potential for
oxidation of the atmosphere being such as to permit oxidation of the constituent(s) from
Group A and to inhibit oxidation of the constituents from Group B; and
b) heating the electrical resistance material in the atmosphere to a temperature in the
range from 800"C to a temperature below the melting point of the alloy so as to oxidise the
constituents of Group A at the surface of the alloy whereby to form a surface layer
consisting essentially of continuous unified oxide of the constituent(s) of Group A.
9. A method according to any one of claims 6 to 8 in which the heat treatment is effected in
an atmosphere comprising water vapour.
10. A method according to claim 9, in which the heat treatment is effected in a single stage.
11. A method according to any one of claims 7 to 10. in which the heating is effected at a
temperature from 8000C to 1475".
12. A method according to claim 11, in which the heating is effected at a temperature from
8000C to about 1300 C
13. A method according to any one of claims 7 to 12, in which the alloy has the following
composition in weight percent:
Group A:
aluminium 3 - 8
Group B:
chromium 12 - 30
iron and/or nickel and/or cobalt balance
14. A method according to claim 13, in which the alloy has the following composition in
weight percent:
Group A:
aluminium 4.5 - 6
Group B:
chromium 19 - 23
iron and/or nickel and/or cobalt balance
15. A method according to any one of claims 7 to 12. in which the alloy has the following
composition in weight percent:
Group A:
aluminium 3 - 8
yttrium, zirconium, hafnium
and/or one or more rare earth elements 0.01 - 0.45
Group B:
chromium 12-30
iron and/or nickel and/or cobalt balance
16. A method according to claim 15, in which the alloy has the following composition in
weight percent:
Group A:
aluminium 4.5 - 6
yttrium, zirconium, hafnium
and/or one or more rare earth elements 0.025 - 0.4
Group B:
chromium 19-23
iron and/or nickel and/or cobalt balance
17. A method according to any one of claims 7 to 12, or 15 or 16, in which the one or more
rare earth elements comprise lanthanum and/or cerium.
18. A method according to claim 17, in which the rare earth elements comprise lanthanum and
cerium and the combined content of such elements in the alloy is in the range from 0.025 to
0.07 percent by weight.
19. A method according to claim 18, in which the lanthanum content is in the range from 0.005
to 0.02 percent by weight.
20. A method according to claim 18 or 19, in which the cerium content is in the range from
0.02 to 0.05 percent by weight.
21. A method according to claim 17, in which the one or more rare earth elements comprises
lanthanum.
22. A method according to claim 21, in which the lanthanum content of the alloy is in the range
from 0.06 to 0.15 percent by weight.
23. A method according to any one of claims 7 to 12, or 15 or 16, in which the alloy contains
zirconium in an amount from 0.1 to 0.4 percent by weight.
24. A method according to any one of claims 6 to 23, in which the surface oxide layer consists
substantially of aluminium oxide.
25. A method of heat treating an alloy material in the fonn of a ribbon substantially as
hereinbefore described with reference to the accompanying drawings.
26. A method of heat treating an alloy material according to any one of the preceding claims,
for manufacturing an electrical resistance heating means.
27. An electrical resistance heating means whenever produced by the method of claim 26.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9714934A GB2327429A (en) | 1997-07-17 | 1997-07-17 | Method of Heat Treating an Alloy Material. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9714934A GB2327429A (en) | 1997-07-17 | 1997-07-17 | Method of Heat Treating an Alloy Material. |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9714934D0 GB9714934D0 (en) | 1997-09-17 |
| GB2327429A true GB2327429A (en) | 1999-01-27 |
Family
ID=10815916
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9714934A Withdrawn GB2327429A (en) | 1997-07-17 | 1997-07-17 | Method of Heat Treating an Alloy Material. |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2327429A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2081747A (en) * | 1980-08-15 | 1982-02-24 | Gen Motors Corp | Oxide whisker growth on cold-rolled aluminium-containing stainless steel |
-
1997
- 1997-07-17 GB GB9714934A patent/GB2327429A/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2081747A (en) * | 1980-08-15 | 1982-02-24 | Gen Motors Corp | Oxide whisker growth on cold-rolled aluminium-containing stainless steel |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9714934D0 (en) | 1997-09-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6045628A (en) | Thin-walled monolithic metal oxide structures made from metals, and methods for manufacturing such structures | |
| EP0574012A2 (en) | Exhaust gas catalytic purifier construction | |
| EP0637359A1 (en) | Heating means for catalyst unit. | |
| EP0501788B1 (en) | Sheathed heater | |
| GB2327429A (en) | Method of Heat Treating an Alloy Material. | |
| US5814164A (en) | Thin-walled, monolithic iron oxide structures made from steels, and methods for manufacturing such structures | |
| KR100265101B1 (en) | Iron-based material having excellent oxidation resistance at elevated temperaturees and process for the production thereof | |
| WO1996016188A9 (en) | Thin-walled, monolithic iron oxide structures made from steels, and methods for manufacturing such structures | |
| US5800634A (en) | Method of manufacturing an electrical resistance heating means | |
| RU2163165C2 (en) | Method and device for manufacture of member of cellular structure from heat-treated double- layer or multi-layer foil | |
| JPH0543984A (en) | Oxidation resisting metal foil and its production | |
| JPH04318160A (en) | Oxidation-resistant metallic foil and its production | |
| JPH11260628A (en) | Superconducting coil of high critical temperature and manufacture of the same | |
| JPH0350199A (en) | Formation of alumina whisker on surface of fe-cr-al type ferritic stainless steel | |
| JPH07183238A (en) | Heating device | |
| JPS5948955B2 (en) | Iron, chromium, aluminum alloy with reticulated alumina coating and method for producing the same | |
| JPS637838A (en) | Manufacture of metallic catalyst carrier | |
| Yahagi et al. | Corrosion-Resistant and Heat-Resistant Metal Composite and Method of Producing | |
| JPH0593258A (en) | Oxidation resistant and corrosion resistant metallic foil and its manufacture | |
| JP3798872B2 (en) | Method for producing metal catalyst carrier | |
| KR920002533B1 (en) | Thermal head | |
| JPS56130476A (en) | Belt for oxidizing atmosphere | |
| JP3287364B2 (en) | Method for producing metal catalyst carrier | |
| JPH08127858A (en) | Formation of metallic oxide film onto ferrous foil, metallic oxide film forming device and ferrous metallic foil | |
| JP2002095975A (en) | Self-heat-generating metal honeycomb structure having insulation layer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |