JP4706441B2 - Spark plug electrode material - Google Patents
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- JP4706441B2 JP4706441B2 JP2005320206A JP2005320206A JP4706441B2 JP 4706441 B2 JP4706441 B2 JP 4706441B2 JP 2005320206 A JP2005320206 A JP 2005320206A JP 2005320206 A JP2005320206 A JP 2005320206A JP 4706441 B2 JP4706441 B2 JP 4706441B2
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- 239000007772 electrode material Substances 0.000 title claims description 19
- 238000002844 melting Methods 0.000 claims description 28
- 230000008018 melting Effects 0.000 claims description 28
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 17
- 229910052735 hafnium Inorganic materials 0.000 claims description 13
- 229910052702 rhenium Inorganic materials 0.000 claims description 13
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- 229910052796 boron Inorganic materials 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910052726 zirconium Inorganic materials 0.000 claims description 3
- 230000003647 oxidation Effects 0.000 description 40
- 238000007254 oxidation reaction Methods 0.000 description 40
- 239000000956 alloy Substances 0.000 description 33
- 229910045601 alloy Inorganic materials 0.000 description 33
- 238000002485 combustion reaction Methods 0.000 description 9
- 230000007423 decrease Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 239000000463 material Substances 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 239000013589 supplement Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- 229910052684 Cerium Inorganic materials 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 229910052746 lanthanum Inorganic materials 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000004299 exfoliation Methods 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
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Description
本発明は内燃機関の点火プラグ用電極材料に関するものである。 The present invention relates to an electrode material for a spark plug of an internal combustion engine.
近年の地球温暖化防止、化石燃料節約などの要求の高まり、それに沿った各種環境規制の動きから、自動車等の排ガス規制が厳しくなってきている。このため、自動車等の内燃機関の燃焼温度が上昇する傾向にあり、自動車等の内燃機関に用いられる点火プラグには、従来以上に耐久性が求められてきている。
従来から本用途の点火プラグ用電極材料には耐酸化性、耐火花損耗性、高温強度等が要求されるため種々のＮｉ基合金が広く使用されている。また、最近では、Ｎｉ基合金単体の電極を用いた点火プラグ以外に、さらに高温に耐えられるように、Ｎｉ基合金からなる電極の放電部分に貴金属を接合し、寿命を改善した点火プラグや、Ｎｉ基合金からなる電極母材内に芯材として熱伝導の良好なＡｇやＣｕを設けたものも多く使用されてきている。
Due to the increasing demand for prevention of global warming and fossil fuel savings in recent years and the movement of various environmental regulations in line with it, exhaust gas regulations for automobiles and the like have become stricter. For this reason, the combustion temperature of internal combustion engines such as automobiles tends to increase, and ignition plugs used in internal combustion engines such as automobiles have been required to be more durable than before.
Conventionally, various Ni-based alloys have been widely used for electrode materials for spark plugs of this application because they are required to have oxidation resistance, spark wear resistance, high temperature strength, and the like. Recently, in addition to a spark plug using a Ni-based alloy single electrode, a spark plug that has improved life by joining a noble metal to the discharge portion of the electrode made of a Ni-based alloy to withstand higher temperatures, An electrode base material made of a Ni-base alloy and provided with Ag or Cu having a good thermal conductivity as a core material has been often used.
このような種々点火プラグの電極材料に用いられるＮｉ基合金には、例えば、加工性等の観点からＣｒを３％程度以下として、耐酸化性と高温強度を補うまたはより高めるための添加元素を含有させるＮｉ基合金の提案がある。
具体的には、低ＣｒのＮｉ基合金において、耐酸化性を補うためにＳｉ、Ｍｎ、Ａｌ等の元素を１種または２種以上、あるいはＹや希土類元素の添加を行う提案が、特開昭６３−１８０３３号（特許文献１参照）、特開平２−３４７３４号（特許文献２参照）、特開平２−３４７３５号（特許文献３参照）、特開平４−４５２３９号（特許文献４参照）、特開平９−２３５６３７号（特許文献５参照）に提案されている。
In such Ni-based alloys used for the electrode materials of various spark plugs, for example, from the viewpoint of workability, Cr is about 3% or less, and an additive element for supplementing or enhancing oxidation resistance and high-temperature strength is included. There is a proposal of a Ni-based alloy to be contained.
Specifically, a proposal to add one or more elements such as Si, Mn, Al, or the addition of Y or a rare earth element to supplement oxidation resistance in a low Cr Ni-based alloy is disclosed in JP JP 63-18033 (refer to Patent Document 1), JP-A-2-34734 (refer to Patent Document 2), JP-A-2-34735 (refer to Patent Document 3), JP-A-4-45239 (refer to Patent Document 4) JP-A-9-235637 (see Patent Document 5).
上述したＣｒをある程度低く抑えた材料は、加工性の点から有望な材料である。しかしながら、上述した合金はいずれも耐酸化性に有効なＣｒを低く抑える替わりに、耐酸化性を補う元素として、Ｓｉ、Ｍｎ、Ａｌを必須添加としているため、Ｎｉ中の合金元素の総量が増加する分、熱伝導率や融点が低下する傾向がある。
耐酸化性を補うための合金元素量が多くなると、熱伝導率が低いことによって電極温度が下がりにくくなり、結果的に高温にさらされることになって酸化しやすくなったり、融点低下による溶損が影響する火花損耗を起こし易くなるおそれがあった。
また、最近の内燃機関の高性能化及び燃焼効率向上、燃焼機構の変換等による高負荷化により、点火プラグ用合金に対する環境は更に苛酷になってきており、上述した合金では必ずしも満足できる特性が得られなくなってきている。
本発明の目的は、上記事情に鑑みて内燃機関の高負荷化、高性能化に対応して、耐酸化性、耐火花損耗性に優れ、さらに製造性も優れた特性を有する点火プラグ用電極材料を提供することである。
The above-described material that suppresses Cr to some extent is a promising material in terms of workability. However, all of the above-mentioned alloys have a low amount of Cr effective for oxidation resistance, but instead of Si, Mn, and Al as essential elements to supplement oxidation resistance, the total amount of alloy elements in Ni increases. As a result, the thermal conductivity and melting point tend to decrease.
When the amount of alloying elements to supplement oxidation resistance increases, the electrode temperature is less likely to decrease due to low thermal conductivity, resulting in exposure to high temperatures that are likely to oxidize, or melting damage due to a decrease in melting point There is a risk that spark wear, which is influenced by, tends to occur.
In addition, due to recent high performance and combustion efficiency improvement of internal combustion engines and high loads due to combustion mechanism conversion, the environment for spark plug alloys has become more severe, and the above-mentioned alloys do not always have satisfactory characteristics. It is no longer available.
In view of the above circumstances, an object of the present invention is an electrode for a spark plug having excellent oxidation resistance, spark wear resistance, and excellent manufacturability in response to higher loads and higher performance of an internal combustion engine. Is to provide materials.
本発明者は点火プラグ用電極材料を検討したところ、点火プラグ用合金の耐酸化性向上させるには熱伝導率を高くすることが必要であり、かつ耐火花損耗性を向上させるには融点を高くすることが有効であるが、これらの２つの必要特性を同時に解決するには、Ｓｉを少量添加すること、Ｈｆおよび／またはＲｅを少量添加すること、Ｍｎ、Ａｌを低下させること、さらに希土類元素の一種以上及び／またはＹを少量添加することを同時に満たすことが有効であることを新たに見出し本発明に到達した。 The present inventor has examined an electrode material for a spark plug, and it is necessary to increase the thermal conductivity in order to improve the oxidation resistance of the spark plug alloy, and in order to improve the spark wear resistance, the melting point must be reduced. Although it is effective to make it high, in order to solve these two necessary characteristics at the same time, a small amount of Si, a small amount of Hf and / or Re, a decrease in Mn and Al, and a rare earth The inventors have newly found out that it is effective to simultaneously add one or more elements and / or a small amount of Y to arrive at the present invention.
すなわち本発明は、質量％で、Ｃ：０．１％以下（０を含む）、Ｓｉ：０．３〜３．０％、Ｍｎ：０．５％未満（０を含む）、Ｃｒ：０．５％未満（０を含む）、Ａｌ：０．３％以下（０を含む）、Ｙ及び希土類元素のうち１種または２種以上を合計で０．０１〜０．３％、ＨｆとＲｅの１種または２種を合計で０．０１〜０．５％、残部はＮｉ及び不可避不純物からなる点火プラグ用電極材料である。
また、本発明の好ましい組成は、質量％で、Ｃ：０．０５％以下（０を含む）、Ｓｉ：０．５〜１．５％、Ｍｎ：０．２％以下（０を含む）、Ｃｒ：０．３％以下（０を含む）、Ａｌ：０．３％以下（０を含む）、Ｙ及び希土類元素のうち１種または２種以上を合計で０．０１〜０．２％、ＨｆとＲｅの１種または２種を合計で０．０１〜０．３％、残部はＮｉ及び不可避不純物とした点火プラグ用電極材料である。
That is, the present invention is, in mass%, C: 0.1% or less (including 0), Si: 0.3 to 3.0%, Mn: less than 0.5% (including 0), Cr: 0.00. Less than 5% (including 0), Al: 0.3% or less (including 0), one or more of Y and rare earth elements in a total of 0.01 to 0.3%, of Hf and Re One or two of them are a total of 0.01 to 0.5%, and the balance is a spark plug electrode material made of Ni and inevitable impurities.
Further, the preferred composition of the present invention is, in mass%, C: 0.05% or less (including 0), Si: 0.5 to 1.5%, Mn: 0.2% or less (including 0), Cr: 0.3% or less (including 0), Al: 0.3% or less (including 0), one or more of Y and rare earth elements in a total of 0.01 to 0.2%, An electrode material for a spark plug in which one or two of Hf and Re are 0.01 to 0.3% in total, and the balance is Ni and inevitable impurities.
上記の組成に加えて、Ｂ、Ｔｉ、Ｎｂ、Ｚｒのうちの少なくとも１種を、Ｂについては０．０１５％以下、Ｔｉについては０．５０％以下、Ｎｂについては１．０％以下、Ｚｒについては０．２０％以下で更に添加することが好ましい。
また上述の本発明の点火プラグ用電極材料は、室温での熱伝導率は３５Ｗ／（ｍ・Ｋ）以上であることが望ましく、更に望ましくは、点火プラグ用電極材料の昇温過程における融点は１４２０℃以上であると良い。
なお、本願において、「Ｙ及び希土類元素のうち１種または２種以上」とは、Ｙと希土類元素とをあわせた元素群の中から選ばれる少なくとも一種以上という意である。
In addition to the above composition, at least one of B, Ti, Nb, and Zr is 0.015% or less for B, 0.50% or less for Ti, and 1.0% or less for Nb. It is preferable to further add about 0.20% or less.
In addition, the above-described spark plug electrode material of the present invention preferably has a thermal conductivity of 35 W / (m · K) or more at room temperature, and more preferably the melting point of the spark plug electrode material during the temperature rising process is It is good that it is 1420 ° C. or higher.
In the present application, “one or more of Y and rare earth elements” means at least one or more selected from the group of elements that combine Y and rare earth elements.
本発明によれば、熱伝導率に優れ、耐酸化性が良好であり、かつ耐火花損耗性が良好で、加工しやすい点火プラグ用電極材料を提供でき、コストを抑えてエンジンの高性能化に対応できるため工業上極めて有効である。 According to the present invention, it is possible to provide an electrode material for a spark plug that has excellent thermal conductivity, good oxidation resistance, and good spark wear resistance, and is easy to process. Therefore, it is extremely effective industrially.
上述したように、本発明の重要な特徴は、Ｍｎ、Ｃｒ、Ａｌを低く抑え、Ｓｉを少量必須添加し、Ｈｆおよび／またはＲｅを少量添加した上で、希土類元素の１種以上および／またはＹを添加することで熱伝導率の低下防止、融点の低下防止を図ったことにある。
本発明者の検討によれば、熱伝導率を高くすることにより、点火プラグとしての使用時に材料温度を低くでき、結果として耐酸化性を向上できる。また、融点低下を防止することにより、点火プラグとしての使用時に火花損耗を起こし難くすることができる。
As described above, the important features of the present invention are that Mn, Cr, Al are kept low, a small amount of Si is essential, and a small amount of Hf and / or Re is added, and then one or more rare earth elements and / or By adding Y, the thermal conductivity is prevented from lowering and the melting point is prevented from lowering.
According to the inventor's study, by increasing the thermal conductivity, the material temperature can be lowered during use as a spark plug, and as a result, the oxidation resistance can be improved. Further, by preventing the melting point from being lowered, it is possible to make it difficult to cause spark wear during use as a spark plug.
以下に本発明で規定した各元素の限定理由を説明する。
Ｃは、加工性を良好にするには低い方が良く、０．１％を超えると焼鈍後の硬さが上昇し、冷間加工性が低下するため０．１％以下に限定する。Ｃの望ましい範囲は０．０５％以下であり、０％（無添加レベル以下）であっても差し支えない。
Ｓｉは、耐酸化性向上に非常に有効な元素である一方、熱伝導率、融点を低下させる元素であるため、良好な耐酸化性を得るために、熱伝導率、融点を大きく低下させない範囲で積極的に添加する。０．３％より少ないと耐酸化性の向上効果が少なく、一方、３．０％を超えて添加すると融点、熱伝導率の低下が大きくなることから、Ｓｉは０．３〜３．０％とした。さらに好ましくはＳｉは０．５〜１．５％がよい。
Ｍｎも、耐酸化性を向上させる元素である一方、熱伝導率、融点を低下させる元素である。本発明のように、Ｓｉをある程度含有する場合には、高い熱伝導率と融点を確保するためにＭｎは低く抑える必要がある。０．５％以上添加すると融点の低下が大きくなることから、Ｍｎは０．５％未満とした。さらに好ましくはＭｎは０．２％以下がよく、０％（無添加レベル以下）であっても差し支えない。
The reason for limitation of each element prescribed | regulated by this invention below is demonstrated.
C is preferable to be low in order to improve the workability, and if it exceeds 0.1%, the hardness after annealing increases and the cold workability decreases, so it is limited to 0.1% or less. The desirable range of C is 0.05% or less, and may be 0% (below the additive-free level).
Si is an element that is very effective for improving oxidation resistance, but it is an element that lowers thermal conductivity and melting point. Therefore, in order to obtain good oxidation resistance, the range that does not greatly reduce thermal conductivity and melting point. Add it positively. If the amount is less than 0.3%, the effect of improving the oxidation resistance is small. On the other hand, if the amount exceeds 3.0%, the melting point and the thermal conductivity are greatly reduced. Therefore, Si is 0.3 to 3.0%. It was. More preferably, Si is 0.5 to 1.5%.
Mn is also an element that improves oxidation resistance, while it is an element that lowers thermal conductivity and melting point. When Si is contained to some extent as in the present invention, it is necessary to keep Mn low in order to ensure high thermal conductivity and melting point. Addition of 0.5% or more increases the melting point, so Mn is less than 0.5%. More preferably, Mn is 0.2% or less, and may be 0% (no additive level or less).
Ｃｒは、耐酸化性を高める元素である一方、熱伝導率を低下させるとともに加工性を劣化させるので、Ｓｉをある程度含有する場合には、高い熱伝導率を確保するためにはＣｒは低く抑える必要がある。０．５％以上添加すると熱伝導率の低下が大きくなることから、Ｃｒは０．５％未満とした。
なお、本発明においては、Ｃｒを０．５％未満に抑えることによる耐酸化性の不足分を、Ｓｉの少量添加とＨｆおよびＲｅの１種または２種の少量添加、およびＹと希土類元素の１種または２種以上を添加することで補うものである。Ｃｒの望ましい範囲は０．３％以下であり、０％（無添加レベル以下）であっても差し支えない。
Ａｌは、耐酸化性を高める元素である一方、熱伝導率を大きく低下させる元素である。本発明のように、Ｓｉをある程度含有する場合には、Ａｌは低く抑える必要がある。Ａｌは０．５％より多く添加すると熱伝導率が大きく低下することから、ここではＡｌは０．３％以下とした。好ましくは、０．１％以下がよく、０％（無添加レベル以下）であっても差し支えない。
While Cr is an element that improves oxidation resistance, it lowers thermal conductivity and degrades workability. Therefore, when Si is contained to some extent, Cr is kept low to ensure high thermal conductivity. There is a need. When 0.5% or more is added, the thermal conductivity decreases greatly, so Cr is made less than 0.5%.
In the present invention, the oxidation resistance deficiency due to the Cr content being suppressed to less than 0.5% is reduced by adding a small amount of Si, a small amount of Hf and Re, or a small amount of Y and rare earth elements. It supplements by adding 1 type, or 2 or more types. The desirable range of Cr is 0.3% or less, and it may be 0% (below the additive-free level).
Al is an element that enhances oxidation resistance, while it is an element that greatly reduces thermal conductivity. When Si is contained to some extent as in the present invention, Al must be kept low. When Al is added in an amount of more than 0.5%, the thermal conductivity is greatly reduced. Therefore, Al is set to 0.3% or less here. Preferably, it is 0.1% or less, and it may be 0% (no additive level or less).
Ｈｆ及びＲｅは、ごく少量の添加で熱伝導率を高く保持したまま、耐酸化性及び高温強度を向上することができるため、添加する必要がある元素である。前述した効果を得るにはＨｆとＲｅの１種または２種を０．０１％以上含有させることが望ましい。しかし、ＨｆとＲｅは高価な元素であり、その合計が０．５％を超えると材料が高価になるので好ましくないだけでなく、多量添加は融点の低下をまねく。Ｈｆ及びＲｅは、１種または２種を合計で０．０１％〜０．５％とした。ＨｆおよびＲｅの好ましい上限は、１種または２種で０．３％である。 Hf and Re are elements that need to be added because they can improve oxidation resistance and high-temperature strength while maintaining high thermal conductivity with a very small amount of addition. In order to obtain the effects described above, it is desirable to contain 0.01% or more of one or two of Hf and Re. However, Hf and Re are expensive elements, and if the total exceeds 0.5%, the material becomes expensive, which is not preferable, and addition of a large amount leads to a decrease in melting point. 1 type or 2 types of Hf and Re were 0.01 to 0.5% in total. The upper limit with preferable Hf and Re is 0.3% by 1 type or 2 types.
Ｙ及び希土類元素は、ごく少量の添加で耐酸化性向上に寄与する元素であり、Ｓｉ等の耐酸化性向上元素とともに添加すると効果が大きいので、１種または２種以上添加する。ここで希土類元素（ＲＥＭ）とは、Ｌａ、Ｃｅ、Ｎｄ、Ｐｒ等のランタノイド元素のことを言う。０．０１％より少ないと耐酸化性の向上効果が小さく、製品設計にもよるが０．３％を超えて添加すると熱間加工性、溶接性が低下するため、Ｙ及び希土類元素は、１種または２種以上を合計で０．０１〜０．３％とした。なお、Ｙ及び希土類元素の好ましい上限は、０．２％以下である。また、熱間加工性、溶接性を重視する場合の好ましい上限は、０．１％である。 Y and rare earth elements are elements that contribute to the improvement of oxidation resistance when added in a very small amount. When added together with an oxidation resistance improving element such as Si, the effect is great, so one or more elements are added. Here, the rare earth element (REM) refers to a lanthanoid element such as La, Ce, Nd, and Pr. If it is less than 0.01%, the effect of improving oxidation resistance is small, and depending on the product design, if added over 0.3%, the hot workability and weldability are lowered. The total amount of seeds or two or more kinds was set to 0.01 to 0.3%. In addition, the upper limit with preferable Y and rare earth elements is 0.2% or less. Moreover, a preferable upper limit when importance is attached to hot workability and weldability is 0.1%.
なお、本発明におけるＮｉ基合金の電極材料には、以下の範囲の元素を添加することができる。
先ず、Ｂ、Ｔｉ、ＮｂおよびＺｒは粒界強化元素として高温での強度、延性、耐粒界酸化性を高めるため、必要に応じて、Ｂ：０．０１５％以下、Ｔｉ：０．５０％以下、Ｎｂ：１．０％以下、Ｚｒ：０．２０％以下の範囲で１種または２種以上を添加することができる。
また、Ｃａ及びＭｇは脱酸、脱硫元素として合金の清浄度を高め、高温での延性を改善することから、必要に応じてＣａ：０．２０％以下、Ｍｇ：０．０５％以下の範囲で添加しても良い。
なお、不可避的不純物として、残留する可能性のある主な元素は、Ｐ、Ｓ、Ｎ、Ｏ等である。これらはできるだけ低い方が望ましいが、Ｐ≦０．０３％、Ｓ≦０．０３％、Ｎ≦０．０５％、Ｏ≦０．０１％であれば点火プラグ電極用材料の基本特性に特に大きな影響を及ぼさないと考えられるので、この範囲であれば許容できる。
In the present invention, the following range of elements can be added to the Ni-base alloy electrode material.
First, B, Ti, Nb, and Zr are used as grain boundary strengthening elements to increase strength at high temperatures, ductility, and resistance to grain boundary oxidation. Therefore, B: 0.015% or less, Ti: 0.50% as necessary. Hereinafter, Nb: 1.0% or less and Zr: 0.20% or less can be added alone or in combination of two or more.
Further, Ca and Mg are deoxidation and desulfurization elements, which increase the cleanliness of the alloy and improve the ductility at high temperature. May be added.
Note that main elements that may remain as unavoidable impurities are P, S, N, O, and the like. These are preferably as low as possible, but if P ≦ 0.03%, S ≦ 0.03%, N ≦ 0.05%, O ≦ 0.01%, the basic characteristics of the spark plug electrode material are particularly large. This range is acceptable because it is thought to have no effect.
次に、本発明で規定した熱伝導率及び溶融開始温度について説明する。
熱伝導率は、加熱した点火プラグ電極の降温に影響し、先端部分が到達する温度を左右する重要な特性の一つであり、高い方が望ましい。
熱伝導率は合金元素の増加につれて低下する傾向があるので、熱伝導率を高く維持するためには合金元素の添加量を抑制する必要がある。一方、耐酸化性を向上させるのは、耐酸化性向上効果のある合金元素を多く添加することが望ましい。
したがって、良好な耐酸化性を確保しつつ、高い熱伝導率を維持するには、本発明の成分範囲の規定のとおり、合金元素の総量を抑制する中で耐酸化性に効果のある元素を適切に選択すること、熱伝導率を低下させにくい合金元素を選択することが必要である。
熱伝導率を高くすることで、点火プラグ電極の温度が下がるので、酸化に対しても有利となる。上記の合金成分の規定範囲内で、効果的な合金元素の選択により、熱伝導率は、点火プラグ電極の温度を低くすることに効果のある３５Ｗ／（ｍ・Ｋ）以上に調整することができる。さらに適切な合金元素の選択により、４０Ｗ／（ｍ・Ｋ）以上に調整することが望ましい。
Next, the thermal conductivity and melting start temperature defined in the present invention will be described.
The thermal conductivity is one of the important characteristics that influence the temperature drop of the heated spark plug electrode and influence the temperature reached by the tip portion, and is preferably higher.
Since thermal conductivity tends to decrease as the number of alloy elements increases, it is necessary to suppress the amount of alloy elements added in order to maintain high thermal conductivity. On the other hand, in order to improve the oxidation resistance, it is desirable to add a lot of alloy elements having an effect of improving the oxidation resistance.
Therefore, in order to maintain high thermal conductivity while ensuring good oxidation resistance, elements that are effective in oxidation resistance while suppressing the total amount of alloy elements as specified in the component range of the present invention. It is necessary to select appropriately and to select an alloy element that does not easily lower the thermal conductivity.
By increasing the thermal conductivity, the temperature of the spark plug electrode is lowered, which is advantageous for oxidation. The thermal conductivity can be adjusted to 35 W / (m · K) or more, which is effective for lowering the temperature of the spark plug electrode, by selecting an effective alloy element within the prescribed range of the alloy components. it can. Furthermore, it is desirable to adjust to 40 W / (m · K) or more by selecting an appropriate alloy element.
融点は、点火プラグ電極の耐火花損耗性に影響する重要な特性の一つであり、高い方が望ましい。融点は合金元素の増加につれて低下する傾向があるので、融点を高く維持するためには合金元素の添加量を抑制する必要がある。一方、耐酸化性を向上させるのは、耐酸化性向上効果のある合金元素を多く添加することが望ましい。
したがって、良好な耐酸化性を確保しつつ、高い融点を維持するには、本発明の成分範囲の規定のとおり、合金元素の総量を抑制する中で耐酸化性に効果のある元素を適切に選択すること、融点を低下させにくい合金元素を選択することが必要である。
上記の合金成分の規定範囲内で、効果的な合金元素の選択により、融点は、点火プラグ電極の耐火花損耗性を向上させることに効果のある１４２０℃以上に調整することができる。
The melting point is one of important characteristics affecting the spark wear resistance of the spark plug electrode, and a higher one is desirable. Since the melting point tends to decrease as the number of alloy elements increases, it is necessary to suppress the amount of alloy element added in order to maintain the melting point high. On the other hand, in order to improve the oxidation resistance, it is desirable to add a lot of alloy elements having an effect of improving the oxidation resistance.
Therefore, in order to maintain a high melting point while ensuring good oxidation resistance, the elements having an effect on oxidation resistance can be appropriately selected while suppressing the total amount of alloy elements as defined in the component range of the present invention. It is necessary to select an alloy element that does not easily lower the melting point.
The melting point can be adjusted to 1420 ° C. or more, which is effective in improving the spark wear resistance of the spark plug electrode, by selecting an effective alloy element within the specified range of the alloy components.
以下の実施例で本発明を更に詳しく説明する。
真空溶解で１０ｋｇ鋼塊を作製し、均質化熱処理後、熱間加工を行い、熱間加工性を確認するとともに、３０ｍｍ角の棒材を作製した。また、一部、冷間加工を行い、加工性を確認した。化学組成を表１に示す。なお、ＲＥＭの添加は希土類元素の混合物として添加しても良いが、今回はＬａ及びＣｅを複合添加した。
試料Ｎｏ．１〜１０は本発明合金、試料Ｎｏ．２１〜２３は比較合金であり、これらの合金に、さらに８００℃で１ｈの焼鈍を行った後、以下に示す各試験の試料とした。
表２に得られた試料の焼鈍後の硬さ、熱伝導率、融点、耐酸化試験後の増量、スケール剥離量を測定した結果を示す。なお、耐酸化試験は試料を８００、９００、１０００℃の大気中にそれぞれ１００ｈｒ暴露して行った。また、熱伝導率は２５℃及び９００℃における値を示したものである。
The following examples further illustrate the present invention.
A 10 kg steel ingot was produced by vacuum melting, and after homogenization heat treatment, hot working was performed to confirm hot workability, and a 30 mm square bar was produced. Moreover, a part was cold-worked and workability was confirmed. The chemical composition is shown in Table 1. Note that REM may be added as a mixture of rare earth elements, but this time La and Ce were added in combination.
Sample No. 1 to 10 are the alloys of the present invention, Sample No. Reference numerals 21 to 23 are comparative alloys. These alloys were further annealed at 800 ° C. for 1 h, and then used as samples for the following tests.
Table 2 shows the results of measuring the hardness, thermal conductivity, melting point, increase after oxidation resistance test, and amount of scale peeling after annealing of the samples obtained. In addition, the oxidation resistance test was performed by exposing the sample to air at 800, 900, and 1000 ° C. for 100 hours. Moreover, thermal conductivity shows the value in 25 degreeC and 900 degreeC.
本発明合金である試料Ｎｏ．１〜１０は何れも２５℃での熱伝導率が高く、３５Ｗ／（ｍ・Ｋ）以上の値を示しており、かつ融点も１４２０℃以上の高い値を維持している。また、硬さも低く、良好な冷間加工性を有している。酸化増量も安定して低く、良好な耐酸化性を示している。
一方、Ｓｉが本発明の規定量を超えて高くＲｅ、Ｈｆを添加していない試料Ｎｏ．２１は融点が１４２０℃より低く、十分な耐火花損耗性が得られないと考えられる。Ｃｒ、Ａｌが本発明の規定量を超えて高くＲｅ、Ｈｆを添加していない試料Ｎｏ．２２は、２５℃での熱伝導率が３５Ｗ／（ｍ・Ｋ）より低く、酸化スケールの剥離も多くなっており、点火プラグ電極に用いた場合に温度上昇が大きくなり、酸化が起こりやすいと考えられる。
また、Ｙ、希土類元素、Ｈｆ、Ｒｅのいずれも添加していない試料Ｎｏ．２３は、熱伝導率、融点は高いものの、高温、特に９００、１０００℃での酸化増量、剥離スケール量が多く、点火プラグ電極材に必要な耐酸化性が十分得られないものと考えられる。
Sample No. which is an alloy of the present invention. Nos. 1 to 10 all have high thermal conductivity at 25 ° C., show values of 35 W / (m · K) or higher, and maintain a high melting point of 1420 ° C. or higher. Moreover, it has low hardness and good cold workability. Oxidation increase is also stable and low, indicating good oxidation resistance.
On the other hand, Sample No. No. in which Si was higher than the specified amount of the present invention and Re and Hf were not added. No. 21 has a melting point lower than 1420 ° C., and it is considered that sufficient spark wear resistance cannot be obtained. Sample No. No. in which Cr and Al are higher than the specified amount of the present invention and Re and Hf are not added. No. 22 has a thermal conductivity at 25 ° C. lower than 35 W / (m · K) and a large amount of oxide scale peeling, and when used for a spark plug electrode, the temperature rises greatly and oxidation is likely to occur. Conceivable.
In addition, Sample No. to which none of Y, rare earth elements, Hf, and Re was added was used. Although No. 23 has a high thermal conductivity and a high melting point, it is considered that the amount of increase in oxidation and the amount of exfoliation scale at high temperatures, particularly 900 and 1000 ° C., are large, and the oxidation resistance necessary for the spark plug electrode material cannot be obtained sufficiently.
本発明は点火プラグ用電極材料に必要な高い熱伝導率、融点、良好な耐酸化性、加工性等の特性に優れているため、良好な耐酸化性、耐火花損耗性が必要とされる内燃機関の点火プラグ用電極に適用できる。
Since the present invention is excellent in characteristics such as high thermal conductivity, melting point, good oxidation resistance and workability required for the electrode material for spark plugs, good oxidation resistance and spark wear resistance are required. It can be applied to an electrode for a spark plug of an internal combustion engine.
Claims (5)
Melting | fusing point is 1420 degreeC or more, The electrode material for spark plugs as described in any one of Claims 1-4 characterized by the above-mentioned.
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| JP4735963B2 (en) * | 2005-09-29 | 2011-07-27 | 日立金属株式会社 | Spark plug electrode material |
| US7823556B2 (en) * | 2006-06-19 | 2010-11-02 | Federal-Mogul World Wide, Inc. | Electrode for an ignition device |
| US20080308057A1 (en) * | 2007-06-18 | 2008-12-18 | Lykowski James D | Electrode for an Ignition Device |
| JP4413951B2 (en) | 2007-07-06 | 2010-02-10 | 日本特殊陶業株式会社 | Spark plug |
| KR101392129B1 (en) | 2009-12-24 | 2014-05-07 | 니혼도꾸슈도교 가부시키가이샤 | Spark Plug |
| KR101397895B1 (en) * | 2010-05-13 | 2014-05-20 | 니혼도꾸슈도교 가부시키가이샤 | Spark plug |
| DE102010024488B4 (en) * | 2010-06-21 | 2012-04-26 | Thyssenkrupp Vdm Gmbh | Nickel-based alloy |
| KR101403796B1 (en) * | 2010-09-24 | 2014-06-03 | 니혼도꾸슈도교 가부시키가이샤 | Spark plug electrode, method for producing same, spark plug, and method for producing spark plug |
| JP5650969B2 (en) * | 2010-09-24 | 2015-01-07 | 住友電気工業株式会社 | Electrode material, spark plug electrode, and spark plug |
| US8664842B2 (en) | 2010-10-26 | 2014-03-04 | Ngk Spark Plug Co., Ltd. | Spark plug |
| JP5697484B2 (en) * | 2011-02-25 | 2015-04-08 | 株式会社デンソー | Spark plug electrode material |
| EP2698439B1 (en) * | 2012-08-17 | 2014-10-01 | Alstom Technology Ltd | Oxidation resistant nickel alloy |
| JP6484160B2 (en) * | 2015-11-02 | 2019-03-13 | 住友電気工業株式会社 | Electrode material, spark plug electrode, and spark plug |
| JP6806158B2 (en) * | 2016-10-07 | 2021-01-06 | 日本製鉄株式会社 | Nickel material and manufacturing method of nickel material |
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