JP2006016970A - Fe-al-c-(ni, cu, mo) sintered alloy valve seat superior in strength and abrasion resistance - Google Patents
Fe-al-c-(ni, cu, mo) sintered alloy valve seat superior in strength and abrasion resistance Download PDFInfo
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この発明は、強度および耐摩耗性に優れたＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシートに関するものであり、特に低排ガス自動車であるＬＰガスおよびＬＮガス自動車のエンジンに組み込まれた場合に、すぐれた耐摩耗性を長期に亘って発揮するＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシートに関するものである。 TECHNICAL FIELD The present invention relates to a valve seat made of a sintered alloy of Fe—Al—C— (Ni, Cu, Mo) having excellent strength and wear resistance, and in particular, engines of LP gas and LN gas vehicles that are low exhaust vehicles. The present invention relates to a valve seat made of an Fe-Al-C- (Ni, Cu, Mo) sintered alloy that exhibits excellent wear resistance over a long period of time when incorporated in a steel sheet.
従来、各種自動車エンジンのバルブシートとして多くのＦｅ系焼結合金製のものが提案され、中でも質量％（以下、％は質量％を示す）で、
Ａｌ：５〜３０％、
Ｃ ：０．２〜３％、
を含有し、残りがＦｅと不可避不純物からなる組成、およびＦｅ−Ａｌ合金相とＦｅ−Ｃ相の２相混在組織、またはＦｅ−Ａｌ合金相とＦｅ−Ｃ相と炭素（Ｃ）相の３相混在組織を有するＦｅ−Ａｌ−Ｃ焼結合金製バルブシートが注目されている。
Conventionally, many valve seats made of Fe-based sintered alloys have been proposed as valve seats for various automobile engines, and in particular, mass% (hereinafter,% indicates mass%),
Al: 5-30%
C: 0.2-3%,
And the remainder composed of Fe and inevitable impurities, and a two-phase mixed structure of Fe—Al alloy phase and Fe—C phase, or 3 of Fe—Al alloy phase, Fe—C phase and carbon (C) phase. A valve seat made of an Fe—Al—C sintered alloy having a phase mixed structure has attracted attention.
また、上記の従来Ｆｅ−Ａｌ−Ｃ焼結合金製バルブシートは、通常の条件、すなわちアンモニア分解ガスやＲＸ分解ガスなどの雰囲気中、１０５０〜１１５０℃の温度に０．５〜２時間保持の条件で焼結しても、原料粉末として用いられるＦｅ粉末、Ａｌ粉末、および炭素粉末の粉末相互の焼結性が悪いために所定の強度をもった焼結体を製造することができず、このため前記原料粉末を所定の配合組成に配合し、混合し、プレス成形してなる圧粉体に５〜１００Ａ／ｍｍ２の電流密度で通電プレス成形焼結（プレス圧力は通常１００ＭＰａ）を施すことにより製造されている。
近年、環境負荷低減のため、エンジンには排ガス低減が求められており、この要求を満たすためにガソリンエンジンにはリーンバーン化や直噴射化が進められており、ディーゼルエンジンにおいては筒内圧力の増加、そしてＬＰＧ、ＬＮＧに代表される代替燃料の採用が進められている。
ＬＰＧ燃料は既にタクシーなどでの使用実績があり、最も代替燃料として期待されている燃料であるが、ガソリン燃料使用環境に比べて
（イ）クリーン燃焼であるために燃焼生成物による潤滑効果が期待できない、
（ロ）室内が乾燥状態になり、より酸化性環境になる、
（ハ）排ガス温度が高温になり、ガソリン燃料の場合排ガス温度は８００℃前後であるがＬＰＧ燃料の場合排ガス温度は９００℃前後に上昇する、などの現象が生じ、そのため、エンジンのバルブシートに対しては、
（ａ）排ガス温度が８００℃前後から９００℃前後に上昇するために、バルブシート基地の強度および硬さが低下してバルブシートの耐摩耗性が低下する、
（ｂ）クリーン燃焼であるために燃焼生成物による潤滑効果が期待できず、また室内が乾燥状態になり、バルブと金属接触が発生し易くなる、
（ｃ）バルブとの接触圧が増加する、などの現象が生じ、そのために金属接触が起り易くかつ摩耗が著しく増大するという問題点が発生した。
In recent years, in order to reduce the environmental load, the engine has been required to reduce exhaust gas. To meet this demand, gasoline engines are being promoted with lean burn and direct injection. Increasing and adoption of alternative fuels represented by LPG and LNG are being promoted.
LPG fuel has already been used in taxis and other fuels, and is expected to be the most alternative fuel. However, compared to gasoline fuel usage environment, (b) clean combustion is expected because of the combustion effect. Can not,
(B) The room becomes dry and becomes a more oxidizing environment.
(C) The exhaust gas temperature becomes high, and in the case of gasoline fuel, the exhaust gas temperature is around 800 ° C, but in the case of LPG fuel, the exhaust gas temperature rises to around 900 ° C. In contrast,
(A) Since the exhaust gas temperature rises from around 800 ° C. to around 900 ° C., the strength and hardness of the valve seat base is lowered, and the wear resistance of the valve seat is lowered.
(B) Since it is clean combustion, the lubrication effect due to the combustion products cannot be expected, and the room is in a dry state, and metal contact with the valve is likely to occur.
(C) A phenomenon such as an increase in the contact pressure with the valve occurs, which causes a problem that metal contact easily occurs and wear significantly increases.
かかる現象に対して、上記の従来Ｆｅ−Ａｌ−Ｃ焼結合金製バルブシートは、上記の通り２相混在組織および３相混在組織をもちかつ前記構成相のうちのＦｅ−Ｃ相が高温耐酸化性に劣るものであるため、特にＬＰガス自動車のエンジンに組み込まれた場合、前記高温の低排ガスによって前記Ｆｅ−Ｃ相の酸化が相対的に速く進行し、これが原因で摩耗が加速されるようになり、さらに前記２相混在組織および３相混在組織の場合、相境界部の強度が焼結性不足が原因で低いために薄肉化および小径化に十分な強度を確保することができない。 In response to such a phenomenon, the above-described conventional Fe—Al—C sintered alloy valve seat has a two-phase mixed structure and a three-phase mixed structure as described above, and the Fe—C phase of the constituent phases has a high temperature acid resistance. Since it is inferior in chemical conversion, especially when incorporated in an engine of an LP gas vehicle, the oxidation of the Fe-C phase proceeds relatively fast by the high temperature low exhaust gas, and this accelerates wear. Furthermore, in the case of the two-phase mixed structure and the three-phase mixed structure, the strength of the phase boundary portion is low due to insufficient sinterability, so that sufficient strength for thinning and diameter reduction cannot be ensured.
そこで、本発明者等は、上述のような観点から、従来Ｆｅ−Ａｌ−Ｃ焼結合金製バルブシートに比べて一層の耐摩耗性と強度の向上を図るべく研究を行った。その結果、原料粉末として、Ｆｅ粉末、Ｆｅ−Ａｌ合金粉末（望ましくはＦｅ−５０％Ａｌ合金粉末）、Ｎｉ粉末、Ｃｕ粉末、Ｍｏ粉末および炭素（Ｃ）粉末を用意し、これら原料粉末を成分組成が、
Ａｌ：２０〜３０％、
Ｃ ：０．１〜１．５％、
Ｎｉ，ＣｕおよびＭｏの内の１種または２種以上の合計｛以下、Ｎｉ，ＣｕおよびＭｏの内の１種または２種以上の合計を（Ｎｉ，Ｃｕ，Ｍｏ）と記す｝：０．１〜５％を含有し、
Ｆｅ：残り、
となるように配合し、通常の条件で混合し、得られた混合粉末をプレス成形して圧粉体を作製し、この圧粉体を真空、望ましくは１０Ｐａ以下の真空中、上記の通常の焼結温度に比して相対的に高い１１５０〜１３００℃の温度に１〜３時間保持の条件で焼結すると、製造されたバルブシートは、焼結時にＦｅ中にＡｌ、炭素（Ｃ）および（Ｎｉ，Ｃｕ，Ｍｏ）が完全に固溶して、Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体単相組織をもつようになり、この結果得られたＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシートは、前記Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体単相組織によって耐摩耗性および強度が一段と向上したものになる、という研究結果を得たのである。
In view of the above, the present inventors have conducted research to further improve wear resistance and strength as compared with conventional valve seats made of a Fe—Al—C sintered alloy. As a result, Fe powder, Fe-Al alloy powder (desirably Fe-50% Al alloy powder), Ni powder, Cu powder, Mo powder and carbon (C) powder are prepared as raw material powders, and these raw material powders are used as components. Composition is
Al: 20-30%,
C: 0.1 to 1.5%
Sum of one or more of Ni, Cu and Mo {Hereinafter, the sum of one or more of Ni, Cu and Mo is described as (Ni, Cu, Mo)}: 0.1 Contains ~ 5%,
Fe: the rest
The mixture is mixed under normal conditions, and the obtained mixed powder is press-molded to produce a green compact. The green compact is vacuumed, preferably 10 Pa or less, and the above-mentioned normal powder is prepared. When sintered at a temperature of 1150 to 1300 ° C., which is relatively higher than the sintering temperature, under the condition of holding for 1 to 3 hours, the produced valve seat has Al, carbon (C) and Fe in Fe during sintering. (Ni, Cu, Mo) completely dissolves to have a single phase structure of Fe-Al-C- (Ni, Cu, Mo) solid solution. As a result, Fe-Al-C- ( The Ni, Cu, Mo) sintered alloy valve seat has the research result that wear resistance and strength are further improved by the Fe-Al-C- (Ni, Cu, Mo) solid solution single phase structure. I got it.
この発明は、上記の研究結果に基づいてなされたものであって、
Ａｌ：２０〜３０％、
Ｃ ：０．１〜１．５％、
を含有し、さらに、
（Ｎｉ，Ｃｕ，Ｍｏ）：０．１〜５％を含有し、
残りがＦｅおよび不可避不純物からなる組成、並びにＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体単相組織を有するＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金で構成してなる、優れた耐摩耗性および強度を有するＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシート、に特徴を有するものである。
This invention was made based on the above research results,
Al: 20-30%,
C: 0.1 to 1.5%
In addition,
(Ni, Cu, Mo): containing 0.1 to 5%,
The remainder is composed of a composition composed of Fe and inevitable impurities, and a Fe-Al-C- (Ni, Cu, Mo) sintered alloy having a single-phase structure of Fe-Al-C- (Ni, Cu, Mo) solid solution. This is characterized by a valve seat made of a sintered alloy of Fe-Al-C- (Ni, Cu, Mo) having excellent wear resistance and strength.
つぎに、この発明のバルブシートを構成するＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金の組成を上記の通りに限定した理由を説明する。
（ａ）Ａｌ
この発明のバルブシートを構成するＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金のＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体単相組織は、原料粉末として、Ｆｅ粉末、Ｆｅ−Ａｌ合金粉末、Ｎｉ粉末、Ｃｕ粉末、Ｍｏ粉末および炭素（Ｃ）粉末を用意し、これら原料粉末をＡｌとＣと（Ｎｉ，Ｃｕ，Ｍｏ）の含有割合が上記の通りになるように限定し、かつ高温真空焼結することによって形成することができ、しかも相境界部が存在しないので一段と高い強度をもつものとなるばかりでなく、前記Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体自体も構成成分であるＦｅ成分で強度、Ａｌ成分で高温耐酸化性、Ｃ成分の作用で硬さ、（Ｎｉ，Ｃｕ，Ｍｏ）成分の作用で一層の基地強度を具備したものとなる。しかし、Ａｌ成分の含有割合が２０％未満では所望のすぐれた高温耐酸化性を確保することができず、一方その含有割合が３０％を越えると、原料粉末としてのＦｅ−Ａｌ合金粉末の配合割合が多くなり過ぎて、焼結時のＦｅへの完全固溶が困難となり、強度および高温耐酸化性低下の原因となる２相混在組織および３相混在組織が出現するようになることから、Ａｌ成分の含有割合を２０〜３０％と定めた。
（ｂ）Ｃ
Ｃ成分には、Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体にあって、これの硬さを向上させ、もってバルブシートの耐摩耗性を向上させる作用があるが、その含有割合が０．１％未満では所望の硬さ向上効果が得られず、一方その含有割合が１．５％を越えると、Ａｌの場合と同様に焼結時のＦｅへの完全固溶が困難となり、２相混在組織および３相混在組織となって、強度および耐摩耗性が急激に低下するようになることから、Ｃ成分の含有割合を０．１〜１．５％と定めた。
（ｃ）Ｎｉ，Ｃｕ，Ｍｏ
これら成分は、基地を固溶強化してバルブシートの特性を一層向上させる作用を有するが、Ｎｉ，Ｃｕ，Ｍｏの内の１種または２種以上を合計で０．１％未満含有しても所望の効果が得られず，一方，５％を越えて含有するとＮｉ相、Ｃｕ相、Ｍｏ相が出現するようになって固溶体単相組織とならず、強度および耐摩耗性が急激に低下するようになることから、Ｎｉ，Ｃｕ，Ｍｏの内の１種または２種以上の合計を０．５〜５％と定めた。
Next, the reason why the composition of the Fe—Al—C— (Ni, Cu, Mo) sintered alloy constituting the valve seat of the present invention is limited as described above will be described.
(A) Al
The Fe—Al—C— (Ni, Cu, Mo) solid solution single-phase structure of the Fe—Al—C— (Ni, Cu, Mo) sintered alloy constituting the valve seat of the present invention is made of Fe powder as a raw material powder. Fe-Al alloy powder, Ni powder, Cu powder, Mo powder and carbon (C) powder are prepared, and the content ratio of Al, C and (Ni, Cu, Mo) in these raw material powders is as described above. In addition to the above-described Fe-Al-C- (Ni, Cu, Mo) The solid solution itself also has the strength of the constituent Fe component, the high temperature oxidation resistance of the Al component, the hardness by the action of the C component, and the further strength of the base by the action of the (Ni, Cu, Mo) component. Become. However, if the content ratio of the Al component is less than 20%, the desired excellent high-temperature oxidation resistance cannot be ensured. On the other hand, if the content ratio exceeds 30%, the blending of the Fe—Al alloy powder as the raw material powder is not possible. Since the ratio becomes too large, it becomes difficult to completely dissolve in Fe during sintering, and a two-phase mixed structure and a three-phase mixed structure that cause a decrease in strength and high-temperature oxidation resistance will appear. The content ratio of the Al component was set to 20 to 30%.
(B) C
The component C is in a Fe-Al-C- (Ni, Cu, Mo) solid solution, and has the effect of improving the hardness thereof, thereby improving the wear resistance of the valve seat. If the content is less than 0.1%, the desired hardness improvement effect cannot be obtained. On the other hand, if the content exceeds 1.5%, it is difficult to completely dissolve in Fe during sintering, as in the case of Al. Since it becomes a two-phase mixed structure and a three-phase mixed structure, and the strength and wear resistance are rapidly decreased, the content ratio of the C component is determined to be 0.1 to 1.5%.
(C) Ni, Cu, Mo
These components have the effect of further improving the characteristics of the valve seat by solid-solution strengthening the base, but even if one or more of Ni, Cu and Mo are contained in a total amount of less than 0.1% The desired effect cannot be obtained. On the other hand, if the content exceeds 5%, Ni phase, Cu phase, and Mo phase appear and do not become a solid solution single phase structure, and the strength and wear resistance are rapidly reduced. Therefore, the total of one or more of Ni, Cu, and Mo is set to 0.5 to 5%.
この発明のＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシートは、Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体単相組織を有するＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金で構成され、前記Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体単相組織は優れた硬さと強度を有するので、特に低排ガス自動車であるＬＰガス自動車のエンジンに組み込まれた場合に、自動車の高速化および高出力化に伴ない、排ガスが９００℃前後の高温に達するにもかかわらず、すぐれた耐摩耗性を長期に亘って発揮し、かつ薄肉化および小径化を可能とするものである。 The valve seat made of a sintered alloy of Fe-Al-C- (Ni, Cu, Mo) of the present invention is Fe-Al-C- (having a single phase structure of Fe-Al-C- (Ni, Cu, Mo) solid solution. An LP gas vehicle which is composed of a sintered alloy of (Ni, Cu, Mo) and has an excellent hardness and strength, and is particularly a low exhaust gas vehicle because the Fe-Al-C- (Ni, Cu, Mo) solid solution structure When it is installed in an engine of this type, it has excellent wear resistance over a long period of time despite the fact that the exhaust gas reaches a high temperature of around 900 ° C as the automobile speeds up and increases its output. And a reduction in diameter are possible.
つぎに、この発明のＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシートを実施例により具体的に説明する。
原料粉末として、−１５０メッシュの還元Ｆｅ粉末、−１５０メッシュのＦｅ−５０％Ａｌ合金粉末、数μｍのＮｉ粉末、−２００メッシュのＣｕ粉末、数μｍのＭｏ粉末および平均粒径：１０μｍの炭素（Ｃ）粉末を用意し、さらに潤滑材としてのステアリン酸亜鉛を用意し、これら原料粉末を表１に示される配合組成に配合し、潤滑材として前記配合粉末に対する割合で０．８％のステアリン酸亜鉛を加えてミキサーにて３０分間混合し、０．７Ｐａの圧力で、外径：４３ｍｍ×内径：３１ｍｍ×高さ：６．５ｍｍの寸法をもったリング状成形体にプレス成形し、この成形体を、３Ｐａの真空中、４００℃に２０分間保持の条件で加熱して前記潤滑材を除去した後、同じく３Ｐａの真空中、通常の焼結温度に比して相対的に高い１２５０℃に１．５時間保持の条件で真空高温焼結し、この結果の焼結体を外径：４０ｍｍ×内径：３４ｍｍ×高さ：６ｍｍの寸法に機械加工し、当接面加工も施すことにより表２に示される成分組成の本発明Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシート（以下、本発明焼結バルブシートという）１〜１３および比較Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシート（以下、比較焼結バルブシートという）１〜３をそれぞれ製造した。
Next, the Fe-Al-C- (Ni, Cu, Mo) sintered alloy valve seat of the present invention will be specifically described with reference to examples.
As raw material powders, -150 mesh reduced Fe powder, -150 mesh Fe-50% Al alloy powder, several μm Ni powder, -200 mesh Cu powder, several μm Mo powder and average particle size: 10 μm carbon (C) Prepare powder, further prepare zinc stearate as a lubricant, blend these raw material powders into the blending composition shown in Table 1, and use 0.8% stearin as a lubricant with respect to the blended powder. Zinc acid was added and mixed for 30 minutes in a mixer, and press-molded into a ring-shaped molded body having a size of outer diameter: 43 mm × inner diameter: 31 mm × height: 6.5 mm at a pressure of 0.7 Pa. The molded body was heated in a condition of 3 Pa in vacuum at 400 ° C. for 20 minutes to remove the lubricant, and then 1250 ° C. which is relatively higher than the normal sintering temperature in a vacuum of 3 Pa. In The sintered body obtained by vacuum high temperature sintering under the condition of holding for 1.5 hours is machined to a size of outer diameter: 40 mm × inner diameter: 34 mm × height: 6 mm, and the contact surface is also processed. 2 of the present invention Fe-Al-C- (Ni, Cu, Mo) sintered alloy valve seats (hereinafter referred to as the present invention sintered valve seat) 1 to 13 and comparative Fe-Al-C- (Ni, Cu, Mo) sintered alloy valve seats (hereinafter referred to as comparative sintered valve seats) 1 to 3 were produced.
また、比較の目的で、原料粉末として、−１５０メッシュの還元Ｆｅ粉末、平均粒径：２０μｍのＡｌ粉末および平均粒径：１０μｍの炭素（Ｃ）粉末を用い、これら原料粉末を表１に示される配合組成に配合し、潤滑材として前記配合粉末に対する割合で０．８％のステアリン酸亜鉛を加えてミキサーにて３０分間混合し、０．７Ｐａの圧力で、外径：４３ｍｍ×内径：３１ｍｍ×高さ：６．５ｍｍの寸法をもったリング状成形体にプレス成形し、この成形体を、同じ条件で脱潤滑材処理した後、１００ＭＰａの圧力を加えながら２５Ａ／ｍｍ２の電流密度で３秒間保持の条件で通電プレス成形焼結し、この結果の焼結体を外径：４０ｍｍ×内径：３４ｍｍ×高さ：６ｍｍの寸法に機械加工し、当接面加工も施すことにより表２に示される成分組成の従来Ｆｅ−Ａｌ−Ｃ焼結合金製バルブシート（以下、従来焼結バルブシートという）１をそれぞれ製造した。 For comparison purposes, -150 mesh reduced Fe powder, Al powder having an average particle size of 20 μm, and carbon (C) powder having an average particle size of 10 μm were used as raw material powders. Blended into the blended composition, 0.8% zinc stearate as a lubricant to the blended powder was added and mixed in a mixer for 30 minutes, and at 0.7 Pa pressure, outer diameter: 43 mm × inner diameter: 31 mm × Height: Press-molded into a ring-shaped molded product having a dimension of 6.5 mm, this molded product was treated with a delubricant under the same conditions, and then applied with a current density of 25 A / mm 2 while applying a pressure of 100 MPa. Table 2 shows the results obtained by subjecting the sintered body to press molding and sintering under the condition of holding for 3 seconds, and machining the resulting sintered body to a size of outer diameter: 40 mm × inner diameter: 34 mm × height: 6 mm, and applying contact surface processing. Ingredients shown in A conventional Fe-Al-C sintered alloy valve seat (hereinafter referred to as a conventional sintered valve seat) 1 having a composition was produced.
この結果得られた本発明焼結バルブシート１〜１３、比較焼結バルブシート１〜３および従来焼結バルブシート１について、その組織を金属顕微鏡を用いて観察し、その結果を表２に示した。また、本発明焼結バルブシート１〜１３、比較焼結バルブシート１〜３および従来焼結バルブシート１のビッカース硬さを測定し、その結果を表２に示した。さらに、強度を評価する目的で圧環強度を測定し、その結果も表２に示した。 The resulting sintered valve seats 1 to 13, comparative sintered valve seats 1 to 3 and the conventional sintered valve seat 1 thus obtained were observed using a metal microscope, and the results are shown in Table 2. It was. Moreover, the Vickers hardness of this invention sintered valve seat 1-13, comparative sintered valve seat 1-3, and the conventional sintered valve seat 1 was measured, and the result was shown in Table 2. Furthermore, the crushing strength was measured for the purpose of evaluating strength, and the results are also shown in Table 2.
次に、上記の本発明焼結バルブシート１〜１３、比較焼結バルブシート１〜３および従来焼結バルブシート１を、それぞれ排気量：５０００ｃｃのＬＰガス自動車のエンジンに組み込み、
回転数：３０００ｒｐｍ、
相手材(バルブ)：ＪＩＳ・ＳＵＨ３５（耐熱鋼）製本体にステライト１２を１ｍｍの厚さで肉盛りしたもの、
試験時間：２００時間、
の条件で実機高速運転摩耗試験を行い、試験後、最大摩耗深さを測定すると共に、相手材であるバルブの最大摩耗深さも測定した。この結果も表２に示した。
Next, the above-described sintered valve seats 1 to 13 of the present invention, comparative sintered valve seats 1 to 3 and the conventional sintered valve seat 1 are incorporated into an engine of an LP gas vehicle having a displacement of 5000 cc,
Rotational speed: 3000rpm,
Counterpart material (valve): A JIS / SUH35 (heat-resistant steel) body with Stellite 12 being 1 mm thick,
Test time: 200 hours
The actual machine high-speed operation wear test was performed under the conditions described above. After the test, the maximum wear depth was measured, and the maximum wear depth of the counterpart valve was also measured. The results are also shown in Table 2.
表１〜２に示される結果から、Ｆｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）固溶体単相組織を有するＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金で構成された本発明焼結バルブシート１〜１３は、いずれも前記Ｆｅ−Ａｌ−Ｃ−Ｍ固溶体単相組織が優れた硬さを有するので優れた耐摩耗性を有しかつ優れた強度を有するので、特に低排ガス自動車であるＬＰガス自動車のエンジンに組み込まれた場合に、自動車の高速化および高出力化に伴ない、排ガスが９００℃前後の高温に達するにもかかわらず、極めて小さい相手攻撃性で、すぐれた耐摩耗性を長期に亘って発揮するのに対して、通電プレス成形燒結して得られた２相混在組織を有するＦｅ−Ａｌ−Ｃ焼結合金で構成された従来焼結バルブシート１並びに真空燒結してもこの発明の条件から外れた組成を有し２相混在組織を有する比較焼結バルブシート１〜３は、強度および耐摩耗性が不足するなどして前記の苛酷な使用条件下では、比較的短時間で使用寿命に至ることが分かる。 From the results shown in Tables 1 and 2, the book composed of a sintered alloy of Fe-Al-C- (Ni, Cu, Mo) having a single-phase structure of Fe-Al-C- (Ni, Cu, Mo) solid solution. Inventive sintered valve seats 1 to 13 are particularly low because the Fe-Al-C-M solid solution single-phase structure has excellent hardness because it has excellent wear resistance and excellent strength. When incorporated in an engine of an LP gas vehicle, which is an exhaust gas vehicle, the exhaust gas reaches a high temperature of around 900 ° C as the speed and output of the vehicle increase. The conventional sintered valve seat 1 composed of a Fe—Al—C sintered alloy having a two-phase mixed structure obtained by sintering by electrification press forming, while exhibiting a long wear resistance. The conditions of the present invention even when vacuum-sintered Comparative sintered valve seats 1 to 3 having a composition that deviates from the above and having a two-phase mixed structure have a relatively short service life under the above severe use conditions due to insufficient strength and wear resistance. It can be seen that
上述のように、この発明のＦｅ−Ａｌ−Ｃ−（Ｎｉ，Ｃｕ，Ｍｏ）焼結合金製バルブシートは、ガソリンエンジンやディーゼルエンジンは勿論のこと、特に自動車の高速化および高出力化に伴ない、排ガスが９００℃前後の高温に達し、かつ低排ガスであるためにバルブシートとバルブの当接が金属同士の直接接触形態をとり、それだけ厳しい使用条件となるＬＰガス自動車のエンジンに組み込まれた場合にも、すぐれた耐摩耗性を長期に亘って発揮し、また高強度を有するので、薄肉化および小径化が可能となるので、自動車の高速化および高出力化、さらに軽量化および小型化に十分満足に対応できるものである。 As described above, the Fe-Al-C- (Ni, Cu, Mo) sintered alloy valve seat of the present invention is used not only for gasoline engines and diesel engines, but particularly for higher speed and higher output of automobiles. Since the exhaust gas reaches a high temperature of around 900 ° C and the exhaust gas is low, the contact between the valve seat and the valve takes a form of direct contact between metals, and it is built into the engine of an LP gas vehicle that has severe conditions. In this case, it has excellent wear resistance over a long period of time and has high strength, so it is possible to reduce the thickness and diameter, thereby increasing the speed and output of automobiles, and further reducing weight and size. It is possible to cope with the conversion sufficiently satisfactorily.
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