【発明の詳細な説明】[Detailed description of the invention]
本発明は、点火プラグ用材料の改良に関するも
のである。
点火プラグは近時ガソリン・エンジンの性能向
上と共に苛酷な条件での使用を余儀なくされ、ま
た排気ガス、公害対策、特殊な使用条件での耐久
性などにより、より良い点火プラグが要望されて
いる。またこれまで消耗品として考えられていた
点火プラグは自動車の場合、廃車までの長期間の
使用が要望されている。
従来の点火プラグは、Pt−Ir10wt％合金、Au
−Pd50wt％合金、Ni属、Ni合金等の点火プラグ
用材料で作つたプラグ本体を、Ni系合金のベー
スに溶接して成る。ところでPt−Ir10wt％合金
のプラグ本体は、結晶粒が小さくて安定していて
長時間高温で使用しても結晶粒の成長が無く比較
的侵食されにくいが、Ni系合金のベース材との
溶接性が悪く、しかも熱サイクルで溶接箇所より
剥離するという問題がある。またAu−Pd50wt％
合金のプラグ本体は、使用中結晶粒が粗大化し、
還元ガスに当たると粒界割れが起こり、侵食され
ていくという問題がある。さらにNi金属及びNi
合金のプラグ本体は、表面酸化が大きいので、点
火しずらいという問題がある。
本発明は、かかる従来の点火プラグ用材料の問
題点を解決し且つ前記の要望を満たすべくなされ
たもので、結晶粒が小さく、高温で長時間使用し
ても結晶粒が成長せず侵食が防止され、またNi
系合金のベースとの溶接性が良好で、熱サイクル
により溶接箇所より剥離することがなく、さらに
表面に酸化膜の発生が無く、点火の容易な点火プ
ラグ用材料を提供せんとするものである。
本発明の点火プラグ用材料は、Pt98〜99.99wt
％と分散されたZrO2又はThO20.01〜2wt％から
成るものである。
このように本発明の点火プラグ用材料は、
Pt98〜99.99wt％にZrO2又はThO2より成る金属
酸化物を0.01〜2wt％分散させたものであるから、
これで作つたプラグ本体は高温で長期間使用して
も分散した微細な金属酸化物粒子がPt結晶粒の
成長を阻害するため結晶粒の成長が無く、しかも
金属酸化物の含有量が少なく化学的、物理的特性
は純Pt金属と殆んど変わらないので、安定して
いて、Ni系合金のベースとの溶接性が良好で、
熱サイクルにより溶接箇所より剥離することがな
いものである。また卑金属が入つていない為、高
温に加熱されても表面には酸化膜の発生が無いの
で、点火が容易である。組成範囲を0.01〜2wt％
に限つたのは、0.01wt％未満では分散される金属
酸化物粒子の量が不十分で純Pt金属と変わらず、
硬さが柔らかいため長期間の使用に対して点火プ
ラグの形状が維持できないからであり、2wt％を
超えると酸化膜が点火プラグ表面に形成されて点
火しにしくくなるためである。
次に本発明による点火プラグ用材料の効果を明
瞭ならしめる為にその具体的な実施例と従来例に
ついて説明する。
実施例 １
Pt99.99wt％にZrO20.1wt％を分散させた材料
でプラグ本体（Ｔ字形プラグで先端部直径0.8mm、
長さ20mm、胴部直径1.5mm、長さ１mm）を作り、
これをNi系合金のベース材に溶接して点火プラ
グを得た。
実施例 ２〜５
下表の成分組成のプラグ本体（実施例１と同一
形状）を作り、これをNi系合金のベース材に溶
接して点火プラグを得た。
The present invention relates to improvements in materials for spark plugs. Spark plugs have recently been forced to be used under harsher conditions as gasoline engines have improved in performance, and better spark plugs have been demanded in order to prevent exhaust gases, prevent pollution, and be durable under special operating conditions. Furthermore, in the case of automobiles, spark plugs, which were previously considered to be consumable items, are required to be used for a long period of time until the car is scrapped. Conventional spark plugs are Pt-Ir10wt% alloy, Au
-The plug body is made of spark plug materials such as Pd50wt% alloy, Ni metal, Ni alloy, etc., and is welded to the Ni-based alloy base. By the way, the plug body made of Pt-Ir 10wt% alloy has small crystal grains and is stable, and even if used at high temperatures for a long time, the crystal grains do not grow and are relatively resistant to corrosion, but it is difficult to weld with the Ni-based alloy base material. The problem is that it has poor properties and peels off from the welded area during thermal cycles. Also, Au−Pd50wt%
The crystal grains of the alloy plug body become coarse during use.
There is a problem in that grain boundary cracking occurs when exposed to reducing gas, leading to erosion. Furthermore, Ni metal and Ni
The alloy plug body has a problem in that it is difficult to ignite due to large surface oxidation. The present invention has been made to solve the problems of conventional materials for spark plugs and to satisfy the above-mentioned needs.The present invention has small crystal grains, and does not grow even when used at high temperatures for long periods of time, and does not erode. Prevented and also Ni
The object of the present invention is to provide a material for spark plugs that has good weldability with the base alloy, does not peel off from the welded part due to thermal cycles, does not form an oxide film on the surface, and is easy to ignite. . The spark plug material of the present invention is Pt98~99.99wt
% and 0.01 to 2 wt% of ZrO 2 or ThO 2 dispersed therein. In this way, the spark plug material of the present invention is
Since it is a product in which 0.01 to 2 wt% of a metal oxide consisting of ZrO 2 or ThO 2 is dispersed in 98 to 99.99 wt% of Pt,
Even if the plug body made using this method is used for a long period of time at high temperatures, the dispersed fine metal oxide particles inhibit the growth of Pt crystal grains, so there is no growth of crystal grains, and the content of metal oxides is small and chemical The physical and physical properties are almost the same as pure Pt metal, so it is stable and has good weldability with Ni-based alloy bases.
It will not peel off from the welded area due to thermal cycles. Furthermore, since it does not contain base metals, no oxide film is formed on the surface even when heated to high temperatures, making it easy to ignite. Composition range 0.01~2wt%
The reason for this is that if it is less than 0.01wt%, the amount of metal oxide particles dispersed is insufficient and it is no different from pure Pt metal.
This is because the shape of the spark plug cannot be maintained over long periods of use due to its soft hardness, and if it exceeds 2wt%, an oxide film is formed on the surface of the spark plug, making it difficult to ignite. Next, in order to clarify the effects of the spark plug material according to the present invention, specific examples and conventional examples thereof will be described. Example 1 A plug body (T - shaped plug, tip diameter 0.8 mm,
20mm long, body diameter 1.5mm, length 1mm),
This was welded to a Ni-based alloy base material to obtain a spark plug. Examples 2 to 5 Plug bodies (same shape as in Example 1) having the compositions shown in the table below were made and welded to a Ni-based alloy base material to obtain spark plugs.
【表】
比較例 １
Pt97wt％にZrO23wt％が分散された材料を線
引加工したところ、クラツクが生じ加工できなか
つた。
比較例 ２
Pt99.993wt％にThO20.07wt％が分散された材
料でプラグ本体（実施例１と同一形状）を作り、
これをNi系合金のベース材に溶接して点火プラ
グを得た。
従来例 １
Au50wt％にPd50wt％を添加させた材料でプ
ラグ本体（実施例１と同一形状）を作り、これを
Ni系合金のベース材に溶接して点火プラグを得
た。
従来例 ２
Pt90wt％にIr10wt％を添加させた材料でプラ
グ本体（実施例１と同一形状）を作り、これを
Ni系合金のベース材に溶接して点火プラグを得
た。
然してこれら実施例１〜５、比較例２及び従来
例１、２の点火プラグを、500℃で30分間Pb中に
浸漬した処、第１〜８図に示すような結果を得
た。（第１〜５図は実施例１〜５、第６図は比較
例２、第７，８図は従来例１、２を示す。）即ち、
実施例１〜５の点火プラグは第１〜５図に示す如
くプラグ本体１の先端周縁が僅かにPbにより侵
食されたが、比較例２の点火プラグは第６図に示
す如くプラグ本体１の先端周縁の侵食度合が実施
例１〜５のものより大きく、従来例１の点火プラ
グは第７図に示す如くプラグ本体１の大部分が
Pbにより侵食され、また従来例２の点火プラグ
は第８図に示す如くプラグ本体１の先端部外周が
Pbにより侵食され、実施例１〜５のものよりか
なり細くなつていた。
次に実施例１〜５、比較例２及び従来例１、２
の点火プラグを、回転数3200rpmのエンジンにて
装着して30000Kmの試運転を行つて試験した処、
実施例１〜５の点火プラグでは第９〜１３図に示
す如くプラグ本体１の先端部の細ぼりが少ない上
に、Ni系合金のベース２との溶接境界に何の異
常も認められなかつたのに対し、比較例２の点火
プラグでは第１４図に示す如く侵食がやや大き
く、従来例１の点火プラグでは第１５図に示す如
くプラグ本体１の表面発火部はぶつぶつとした溶
融したような現象が認められ、先端部は侵食さ
れ、極端に細くなつていた。また従来例２の点火
プラグでは第１６図に示す如くプラグ本体１の先
端部の侵食による細ぼりは比較的少ないのである
が、Ni系合金のベース２との溶接境界からプラ
グ本体１が今にも剥離しそうな状態を呈してい
た。
以上詳記した通り本発明の点火プラグ用材料
は、Pt素地中に微量のZrO2又はThO2から成る金
属酸化物を分散させて成るので、結晶粒が細かく
安定していて、高温で長期間使用しても結晶粒が
成長せず、侵食が防止され、寿命が著しく増長で
きる。また化学的、物理的特性が純Ptと殆んど
変わらず安定しているので、Ni系合金のベース
との溶接性が良好で、熱サイクルにより溶接箇所
より剥離することがない。さらに表面に酸化膜の
発生が無いので点火が容易である等の優れた効果
がある。[Table] Comparative Example 1 When a material containing 97wt% Pt and 3wt% ZrO 2 dispersed therein was wire-drawn, cracks occurred and processing could not be performed. Comparative Example 2 A plug body (same shape as Example 1) was made of a material in which 0.07 wt% of ThO 2 was dispersed in 99.993 wt% of Pt.
This was welded to a Ni-based alloy base material to obtain a spark plug. Conventional example 1 A plug body (same shape as Example 1) is made from a material in which 50wt% Au and 50wt% Pd are added, and this
A spark plug was obtained by welding to a Ni-based alloy base material. Conventional example 2 A plug body (same shape as Example 1) is made from a material in which 90wt% Pt and 10wt% Ir are added, and this is
A spark plug was obtained by welding to a Ni-based alloy base material. When the spark plugs of Examples 1 to 5, Comparative Example 2, and Conventional Examples 1 and 2 were immersed in Pb at 500 DEG C. for 30 minutes, the results shown in FIGS. 1 to 8 were obtained. (Figs. 1 to 5 show Examples 1 to 5, Fig. 6 shows Comparative Example 2, and Figs. 7 and 8 show Conventional Examples 1 and 2.) That is,
In the spark plugs of Examples 1 to 5, the tip periphery of the plug body 1 was slightly corroded by Pb as shown in FIGS. The degree of erosion around the tip is greater than that of Examples 1 to 5, and the spark plug of Conventional Example 1 has a large part of the plug body 1 as shown in FIG.
The spark plug of Conventional Example 2 is corroded by Pb, and the outer periphery of the tip of the plug body 1 is
It was corroded by Pb and was considerably thinner than those of Examples 1 to 5. Next, Examples 1 to 5, Comparative Example 2, and Conventional Examples 1 and 2
The spark plug was installed on an engine with a rotation speed of 3200 rpm and tested for 30000 km.
In the spark plugs of Examples 1 to 5, as shown in Figs. 9 to 13, the tip of the plug body 1 had less narrowing, and no abnormality was observed at the welding boundary with the Ni-based alloy base 2. On the other hand, in the spark plug of Comparative Example 2, the erosion was somewhat large as shown in FIG. 14, and in the spark plug of Conventional Example 1, the surface ignition part of the plug body 1 had a lumpy, melted appearance as shown in FIG. A phenomenon was observed, and the tip was eroded and became extremely thin. In addition, in the spark plug of Conventional Example 2, as shown in Fig. 16, there is relatively little narrowing due to erosion at the tip of the plug body 1, but the plug body 1 is about to peel off from the welding boundary with the Ni-based alloy base 2. It appeared to be in a dire condition. As detailed above, the spark plug material of the present invention is made by dispersing a small amount of metal oxide consisting of ZrO 2 or ThO 2 in a Pt matrix, so the crystal grains are fine and stable, and it can be used at high temperatures for a long period of time. Even when used, crystal grains do not grow, corrosion is prevented, and the service life can be significantly extended. In addition, since the chemical and physical properties are almost the same as pure Pt and are stable, it has good weldability with the Ni-based alloy base and does not peel off from the welded area due to thermal cycles. Furthermore, since no oxide film is formed on the surface, it has excellent effects such as easy ignition.
【図面の簡単な説明】[Brief explanation of drawings]
第１図乃至第８図は500℃30分間Pb中に浸漬し
た直後の点火プラグの状態を示すもので、第１〜
５図は本発明の材料を用いて製作した点火プラ
グ、第６図は比較例の材料を用いて製作した点火
プラグ、第７，８図は従来の材料を用いて製作し
た点火プラグ、第９図乃至第１６図は回転数
3200rpmのエンジンに装着して30000Kmの試運転
を行つて試験したプラグを示すもので、第９〜１
３図は本発明の材料を用いて製作した点火プラ
グ、第１４図は比較例の材料を用いて製作した点
火プラグ、第１５，１６図は従来の材料を用いて
製作した点火プラグである。
Figures 1 to 8 show the state of the spark plug immediately after being immersed in Pb at 500°C for 30 minutes.
Figure 5 shows a spark plug manufactured using the material of the present invention, Figure 6 shows a spark plug manufactured using a material of a comparative example, Figures 7 and 8 show a spark plug manufactured using a conventional material, and Figure 9 shows a spark plug manufactured using a conventional material. Figures to Figures 16 are rotational speeds
This shows the plug that was tested by installing it on a 3200rpm engine and performing a 30000km trial run.No. 9 to 1
FIG. 3 shows a spark plug manufactured using the material of the present invention, FIG. 14 shows a spark plug manufactured using a material of a comparative example, and FIGS. 15 and 16 show a spark plug manufactured using a conventional material.