This application is the National Stage of PCT/DE2011/001174 filed on Jun. 8, 2011, which claims priority under 35 U.S.C. §119 of German Application No. 10 2010 024 488.0 filed on Jun. 21, 2010, the disclosure of which is incorporated by reference. The international application under PCT article 21(2) was not published in English.
1. Field of the Invention
The invention relates to a nickel-based alloy.
2. Description of the Related Art
Nickel-based alloys are used, among other things, for producing electrodes of ignition elements for internal combustion engines. These electrodes are exposed to temperatures between 400° C. and 950° C. In addition, the atmosphere alternates between reducing and oxidizing conditions. This produces material destruction or a material loss caused by high-temperature corrosion in the surface region of the electrodes. The production of the ignition spark leads to further stress (spark erosion). Temperatures of several 1000° C. occur at the foot point of the ignition spark, and in the event of a break-through, currents of up to 100 A flow during the first nanoseconds. At every spark-over, a limited material volume in the electrodes is melted and partly evaporated, and this produces a material loss.
In addition, vibrations of the engine increase the mechanical stresses.
An electrode material should have the following properties:
Nickel alloys, in particular, have a good potential for fulfilling this spectrum of properties. They are inexpensive in comparison with precious metals, they do not demonstrate any phase conversions up to the melting point, like cobalt or iron, they are comparatively non-sensitive to carburization and nitration, they have good heat resistance and good corrosion resistance, and they can be deformed well and welded.
Wear caused by high-temperature corrosion can be determined by means of mass change measurements as well as by means of metallographic studies after aging at predetermined test temperatures.
For both damage mechanisms, high-temperature corrosion and spark erosion, the type of oxide layer formation is of particular significance.
In order to achieve an optimal oxide layer formation for the concrete application case, various alloy elements are known in the case of nickel-based alloys.
In the following, all the concentration information is given in % by mass unless explicitly noted otherwise.
From DE 29 36 312, a nickel alloy has become known, consisting of about 0.2 to 3% Si, about 0.5% or less Mn, at least two metals, selected from the group consisting of about 0.2 to 3% Cr, about 0.2 to 3% Al, and about 0.01 to 1% Y, remainder nickel.
In DE-A 102 24 891 A1, an alloy on the basis of nickel is proposed, which has 1.8 to 2.2% silicon, 0.05 to 0.1% yttrium and/or hafnium and/or zirconium, 2 to 2.4% aluminum, remainder nickel. Such alloys can be worked only under difficult conditions, with regard to the high aluminum and silicon contents, and are therefore not very suitable for technical large-scale use.
In EP 1 867 739 A1, an alloy on the basis of nickel is proposed, which contains 1.5 to 2.5% silicon, 1.5 to 3% aluminum, 0 to 0.5% manganese, 0.5 to 0.2% titanium in combination with 0.1 to 0.3% zirconium, whereby the zirconium can be replaced, in whole or in part, by double the mass of hafnium.
In DE 10 2006 035 111 A1, an alloy on the basis of nickel is proposed, which contains 1.2 to 2.0% aluminum, 1.2 to 1.8% silicon, 0.001 to 0.1% carbon, 0.001 to 0.1% sulfur, maximally 0.1% chromium, maximally 0.01% manganese, maximally 0.1% Cu, maximally 0.2% iron, 0.005 to 0.06% magnesium, maximally 0.005% lead, 0.05 to 0.15% Y, and 0.05 to 0.10% hafnium or lanthanum or 0.05 to 0.10% hafnium and lanthanum, in each instance, remainder nickel, and production-related contaminants.
In the brochure “Drähte von ThyssenKrupp VDM Automobilindustrie” Publication N 581, Jan. 2006 Edition, on page 18, an alloy according to the state of the art is described, NiCr2MnSi with 1.4 to 1.8% Cr, max. 0.3% Fe, max. 0.5% C, 1.3 to 1.8% Mn, 0.4 to 0.65% Si, max. 0.15% Cu, and max. 0.15% Ti. As an example, a batch T1 of this alloy is indicated in Table 1. Furthermore, in Table 1, the batch T2 is indicated, which was melted according to DE 2936312 with 1% Si, 1% Al, and 0.17% Y. An oxidation test at 900° C. in air was conducted on these alloys, whereby the test was interrupted every 96 hours and the mass change in the samples caused by oxidation was determined (net mass change).
It is the goal of the object of the invention to make available a nickel alloy that leads to an increase in the lifetime of components produced from it, which can be brought about by means of increasing the spark erosion resistance and corrosion resistance, with simultaneous good deformability and weldability (workability).
The goal of the object of the invention is achieved by means of a nickel-based alloy containing (in % by mass)
Surprisingly, it has been shown that the addition of silicon is more advantageous for the spark erosion resistance and corrosion resistance than the addition of aluminum.
The silicon content lies between 0.8 and 2.0%, whereby preferably defined contents within the spread ranges can be adjusted:
This holds true in the same manner for the element aluminum, which is adjusted in contents between 0.001 to 0.10%. Preferred contents can be present as follows:
This holds true likewise for the element iron, which is adjusted in contents between 0.01 to 0.20%. Preferred contents can be present as follows:
Carbon is adjusted in the alloy in the same manner, specifically in contents between 0.001-0.10%. Preferably, contents can be adjusted in the alloy as follows:
Nitrogen is adjusted in the alloy likewise, specifically in contents between 0.0005-0.10%. Preferably, contents can be adjusted in the alloy as follows:
Magnesium is adjusted in contents 0.0001 to 0.08%. Preferably, the possibility exists of adjusting this element in the alloy as follows:
The alloy can furthermore contain calcium in contents between 0.0002 and 0.06%.
The oxygen content is adjusted in the alloy with a content of 0.0001 to 0.010%. Preferably, the following content of oxygen can be adjusted:
The elements Mn and Cr can be present in the alloy as follows:
Furthermore, it is advantageous to add yttrium to the alloy with a content of 0.03% to 0.20%, whereby a preferred range is:
Another possibility is to add hafnium to the alloy with a content of 0.03% to 0.25%, whereby a preferred range is:
Likewise, zirconium can be added to the alloy with a content of 0.03 to 0.15.
The addition of cerium with a content of 0.03 to 0.15 is also possible.
Furthermore, lanthanum can be added with a content of 0.03 to 0.15%.
The alloy can contain Ti with a content of up to max. 0.15%.
The copper content is restricted to max. 0.50%; preferably, it lies at max. 0.20%.
Finally, the elements cobalt, tungsten, molybdenum, and lead can also be present as contaminants, in contents as follows:
The nickel-based alloy according to the invention can preferably be used as a material for electrodes of ignition elements of internal combustion engines, particularly of spark plugs for gasoline engines.
The object of the invention will be explained in greater detail using the following examples. oxidation test at 900° C. in the batches from Tables 2 and 3.
The object of the invention will be explained in greater detail using the following examples.
Table 1 shows alloy compositions that belong to the state of the art.
In Table 2, examples of nickel alloys not according to the invention, with 1% aluminum and various contents of elements with oxygen affinity are shown: L1 contains 0.13% Y, L2 0.18% Hf, L3 0.12% Y and 0.20 Hf, L4 0.13% Zr, L5 0.043% Mg, and L6 0.12% Sc. Furthermore, these batches contain different oxygen contents in the range of 0.001% to 0.004% and Si contents<0.01%.
In Table 3, examples of nickel alloys according to the invention are shown, with approx. 1% silicon and various contents of elements with oxygen affinity: E1 and E2 contain approx. 0.1% Y, in each instance, E3, E4, and E5 contain approx. 0.20% Hf, in each instance, E6 and E7 contain approx. 0.12% Y and 0.14 or 0.22 Hf, in each instance, E8 and E9 contain approx. 0.10% Zr, in each instance, E10 0.037% Mg, E11 contains 0.18% Hf and 0.055% Mg, E12 contains 0.1% Y and 0.065% Mg, and E13 0.11% Y and 0.19% Hf and 0.059% Mg. Furthermore, these batches contain various oxygen contents in the range of 0.002% to 0.007%, and Al contents between 0.003 and 0.035%.
An oxidation test at 900° C. in air was conducted on these alloys, as well as on the alloys in Table 1, whereby the test was interrupted every 24 hours and the mass change of the samples caused by oxidation was determined (net mass change mN). In these tests, the samples were in ceramic crucibles, so that any oxides that flaked off were collected. By weighing the crucible before the test (mT) and weighing the crucible with the collected flakes and the sample (mG) when the test was interrupted, in each instance, it is possible to determine the amount of the flaked-off oxides (mA) together with the net mass change.
mA=mG−mT−mN
In this connection, it has been shown that all the batches from Table 2 and 3, except for the batch L6, which contained Sc, do not show any flaking (
As can be seen in
The reasons for the claimed limits for the alloy can therefore be stated in detail as follows:
A minimum content of 0.8% Si is necessary in order to obtain the oxidation resistance and the increasing effect of the Si. At greater Si contents, workability worsens. The upper limit is therefore established at 2.0% by weight Si.
Aluminum worsens the oxidation resistance when added in the range of 1%. For this reason, the aluminum content is restricted to max. 0.10%. An overly low Al content increases the costs. The Al content is therefore established at greater than or equal to 0.001%.
Iron is limited to 0.20%, because this element reduces the oxidation resistance. An overly low Fe content increases the costs in the production of the alloy. The Fe content is therefore greater than or equal to 0.01%.
The carbon content should be less than 0.10%, in order to guarantee workability. Overly low C contents cause increased costs in the production of the alloy. The carbon content should therefore be greater than 0.001%.
Nitrogen is limited to 0.10%, because this element reduces the oxidation resistance. Overly low N contents cause increased costs in the production of the alloy. The nitrogen content should therefore be greater than 0.0005%.
As
The oxygen content must be less than 0.010% to guarantee the producibility of the alloy. Overly low oxygen contents cause increased costs. The oxygen content should therefore be greater than 0.0001%.
Manganese is limited to 0.1%, because this element reduces the oxidation resistance.
Chromium is limited to 0.10%, because this element, as the example of T1 in
Copper is limited to 0.50%, because this element reduces the oxidation resistance.
The contents of sulfur should be kept as low as possible, because this surfactant element impairs the oxidation resistance. For this reason, max. 0.008% S is established.
Just like Mg, even very slight Ca contents already improve processing, by means of binding sulfur, thereby preventing the occurrence of NiS eutectics with a low melting point. For this reason, a minimum content of 0.0002% is therefore required for Ca. At overly high contents, intermetallic Ni—Ca phases can occur, which again clearly worsen the workability. The Ca content is therefore limited to 0.06%.
A minimum content of 0.03% Y is necessary in order to obtain the effect of the Y of increasing the oxidation resistance. The upper limit is placed at 0.20% for cost reasons.
A minimum content of 0.03% Hf is necessary in order to obtain the effect of the Hf of increasing the oxidation resistance. The upper limit is placed at 0.25% Hf for cost reasons.
A minimum content of 0.03% Zr is necessary in order to obtain the effect of the Zr of increasing the oxidation resistance. The upper limit is placed at 0.15% Zr for cost reasons.
A minimum content of 0.03% Ce is necessary in order to obtain the effect of the Ce of increasing the oxidation resistance. The upper limit is placed at 0.15% Ce for cost reasons.
A minimum content of 0.03% La is necessary in order to obtain the effect of the La of increasing the oxidation resistance. The upper limit is placed at 0.15% La for cost reasons.
The alloy can contain up to 0.15% Ti without its properties becoming worse.
Cobalt is limited to max. 0.50% because this element reduces the oxidation resistance.
Molybdenum is limited to max. 0.10% because this element reduces the oxidation resistance. The same holds true also for tungsten and also for vanadium.
The content of phosphorus should be less than 0.020%, because this surfactant element impairs the oxidation resistance.
The content of boron should be kept as low as possible, because this surfactant element impairs the oxidation resistance. For this reason, max. 0.005% B is established.
Pb is limited to max. 0.005%, because this element reduces the oxidation resistance. The same holds true for Zn.
Number | Date | Country | Kind |
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10 2010 024 488 | Jun 2010 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/DE2011/001174 | 6/8/2011 | WO | 00 | 11/29/2012 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2011/160617 | 12/29/2011 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
4329174 | Ito et al. | May 1982 | A |
5059257 | Wanner et al. | Oct 1991 | A |
20040013560 | Hrastnik | Jan 2004 | A1 |
20100003163 | Kloewer et al. | Jan 2010 | A1 |
Number | Date | Country |
---|---|---|
16 08 116 | Dec 1970 | DE |
29 36 312 | Mar 1980 | DE |
102 24 891 | Dec 2003 | DE |
10 2006 035 111 | Feb 2008 | DE |
1 867 739 | Dec 2007 | EP |
943141 | Nov 1936 | GB |
Entry |
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International Search Report of PCT/DE2011/001174, date of mailing Jan. 25, 2012. |
Drähte von ThyssenKrupp VDM Automobilindustrie, [Wire from ThyssenKrupp VDM Automotive Industry] Publication N 581, Jan. 2006 Edition. Spec., p. 4. |
Number | Date | Country | |
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20130078136 A1 | Mar 2013 | US |