JP4173376B2

JP4173376B2 - Heat resistant stainless steel foil and metal carrier for metal carrier for exhaust gas purification with good diffusion bonding

Info

Publication number: JP4173376B2
Application number: JP2003005373A
Authority: JP
Inventors: 篤比古今井; 和俊岩見; 裕一岡崎; 雅幸糟谷; 幹雄山中
Original assignee: Nippon Steel Chemical and Materials Co Ltd
Current assignee: Nippon Steel Chemical and Materials Co Ltd
Priority date: 2003-01-14
Filing date: 2003-01-14
Publication date: 2008-10-29
Anticipated expiration: 2023-01-14
Also published as: JP2004216242A

Description

【０００１】
【発明の属する技術分野】
本発明は自動車排ガスの浄化用メタル担体に用いられる耐熱ステンレス鋼箔および該箔を用いたメタル担体に関わる。
【０００２】
【従来の技術】
自動車排ガスの浄化する触媒コンバーターとして、耐熱鋼箔をハニカム材とするメタル担体の重要性が増してきている。メタル担体はセラミック担体に比べて排気ガスの浄化能などが優れてはいるが、高価であるため使用される車種は一部の高級車種に限られている。したがってメタル担体のコストを少しでも下げる努力がなされている。メタル担体は通常ろう接で平箔と波箔を接合して製造されるが、高価なろう材を使わないで拡散接合で製造する技術が特許文献１や特許文献２などに提案されている。拡散接合の場合箔材の表面粗さによって拡散接合性が左右され、特許文献３では、ハニカム体（拡散接合後）の表面粗さを算術平均粗さＲａで０．１５〜３μｍと規定してγ−アルミナなどの触媒担持層がハニカム体（拡散接合後）に好適に形成されることを開示している。また特許文献４では拡散接合に好適な箔の表面粗さを１０点平均粗さＲｚ（旧ＪＩＳ）で０．１〜０．３にすることを開示している。
【０００３】
さらに特許文献５においては、箔の拡散接合性を左右するのは旧ＪＩＳの最大粗さＲｍａｘや、やはり旧ＪＩＳの十点平均粗さＲｚなどよりＲａがより正確な指標であることを明らかにし、拡散接合性の良い箔の表面粗さをＲａで０．００１〜０．２μｍとした。
【０００４】
【特許文献１】
特開平１−２７０９４７号公報
【特許文献２】
特開平２−１４７４７号公報
【特許文献３】
実開平３−１０２２３７号公報
【特許文献４】
特開平３−１１８８３９号公報
【特許文献５】
特開平８−３８９１２号公報
【０００５】
【発明が解決しようとする課題】
特許文献５に記載の発明により、メタル担体の製造に用いることのできる拡散接合性の良好な箔を提供することが可能になったが、メタル担体の耐久性を向上してさらに高い信頼性を有するメタル担体を提供するためには、拡散接合性の更なる向上が要求されている。
【０００６】
本発明は、メタル担体用箔材のより一層の拡散接合性の向上を実現し、メタル担体を高い信頼性のもとに供給することを目的とする。
【０００７】
【課題を解決するための手段】
本発明はかかる問題点に鑑み、メタル担体用箔材の拡散接合性とその表面粗さの関係を追及した結果、Ｒａに加えて輪郭曲線のスキューネスＲｓｋを組み合わせることにより、拡散接合性の極めて良好な箔を得ることができるという知見に達したことによる。
【０００８】
すなわち本発明の第１のものは、表面粗さがＲａで０．３２μｍ以上０．４μｍ以下で、かつＲａとＲｓｋとの関係が下記（１）式の関係にあることを特徴とする拡散接合性の良好な排気ガス浄化用メタル担体用耐熱ステンレス鋼箔である。
Ｒｓｋ≦−１０×（Ｒａ−０．２）（１）
【０００９】
また本発明の第２のものは、耐熱ステンレス鋼箔で構成されたハニカムを耐熱ステンレス鋼製の外筒に挿入して拡散接合された排気ガス浄化用メタル担体において、前記ステンレス鋼箔の表面粗さが上記第１の発明の範囲内にあることを特徴とする排気ガス浄化用メタル担体である。
【００１０】
【発明の実施の形態】
以下に本発明を詳しく説明する。金属の拡散接合性はその表面粗さが小さい方が良好になることは多くの文献等で開示され、公知であった。この場合の試験材は薄板や棒で、その場合は旧ＪＩＳの最大粗さＲｍａｘや、やはり旧ＪＩＳの十点平均粗さＲｚなどが拡散接合性を左右する指標として使われてきた。前者は基準長さ内で最も高い山頂と最も深い谷底の差高を測定し、後者は最も高い山から５番目までの山頂の高さの平均と最も低い谷から５番目までの谷底の深さの平均との差高を測定するものである。すなわちこれらのパラメータは表面粗さの極値を表す。拡散接合性を左右する因子は、金属面同士を小さな圧力で接触させたときに相互に接触する面積の大小で、これが大であるほど拡散接合性は良好となる。薄板や棒など形状的に比較的リジッドな材料では、これらの表面粗さの極値が接合面の接触状況を左右するので、これらのパラメータが拡散接合性の良い指標となる。
【００１１】
一方箔などの形状的に柔らかな材料では、特許文献５に記載のように、極値を与える山と山の中間の部分もある程度材料が変形して接合面が相互になじむため、極値を表すＲｍａｘやＲｚより平均的な凹凸の程度を表すＲａの方がより的確に拡散接合性を表すことが解明された。この結果から特許文献５においては、拡散接合性の良い箔の表面粗さをＲａで０．００１〜０．２μｍとした。
【００１２】
その後多くの箔を調べるうちに、Ｒａのみでは拡散接合性の良好な箔の表面粗さの特徴を的確に捉えることができないことを新たに知見した。すなわち特許文献５に規定するＲａの範囲内の箔でも拡散接合性の悪いものがあり、またこの範囲外のものでも拡散接合性の良好なものがあることが判明した。
【００１３】
すなわち箔の典型的な輪郭曲線が図２のごとく、山の部分は比較的滑らかな高原台地状になっており、ところどころに深い谷が存在するような形状を有している場合には、Ｒａが０．２μｍ以下でも０．２μｍ超でも拡散接合性が非常に良好となる。これらから判るように、一部に深い谷があるためにＲａはやや大きくなるがこれらは拡散接合性には悪影響せず、大部分の山の部分が滑らかであれば拡散接合性は良好であることを示す。このような輪郭曲線の箔は、表面粗さの大きいローラーで１パス当たりの圧下率を大きくとって能率の良い圧延を数パス行い、最後に極めて滑らかな表面のローラーで仕上げ圧延したときに得られることが判明した。
【００１４】
逆に箔の典型的な輪郭曲線が図３に示すごとく、ところどころに比較的高い山がありかつ大部分の谷が滑らかで、図２の曲線の上下逆さまの形をしている場合には、たとえＲａが０．２μｍ以下でも上記のような非常に良好な拡散接合性を得ることができないことが判った。このような箔はオーバーホール直後の圧延ローラーで圧延したときによく出るものである。すなわち傷んだ圧延ローラーの表面を研削し、さらに研磨して表面を滑らかにするも、深い研削疵が残ったようなローラーで圧延すると図３のような輪郭曲線の箔が得られる。この場合、ところどころの山によって拡散接合性は悪化するが、Ｒａは大部分の谷部の滑らかさに影響されて比較的小さくなったものである。
【００１５】
以上の検討結果から、拡散接合性にはところどころにある深い谷は影響しないが、ところどころにある高い山は悪影響する。したがって突出した山と急峻な谷の多さを区別して表現できる表面粗さパラメータのスキューネスＲｓｋ（輪郭曲線の三乗平均／同二乗平均^3/2で無次元）がＲａとともに拡散接合性の評価基準になり得ることを暗示している。すなわちＲｓｋは、輪郭曲線に突出した山が多ければ正となり、急峻な谷が多ければ負となる無次元の値である。
【００１６】
本発明者らは圧延ローラーの表面仕上げ状況をいくつかに変化させて２０Ｃｒ−５Ａｌ鋼の５０μｍ箔を３０μｍまで圧延し、さらに圧延された箔の表面を種種の粗さのエメリー紙で研磨するなどして、各種の表面性状の箔を得た。かくして得られた各箔のＲａとＲｓｋを表面粗さ計で測定した。この際の基準長さは０．８ｍｍ、触針径２μｍ、その他はＪＩＳＢ０６０１（２００１年）に従った。さらにこれらの箔を１００Ｌ×１０Ｗの大きさに夫々２枚切り、図４に示すようにそれら箔１１の先端の１０Ｌ×１０Ｗが重なるようにして、ここにあらかじめ酸化処理した２０Ｃｒ−５Ａｌ鋼製のブロック１２を台座１３の上に乗せて９０ｇの荷重が加わるようにセットし、１２００℃×２０分の真空熱処理を行った。なお１２００℃での真空度は２〜５×１０^-5Ｔｏｒｒであった。熱処理後に箔の両端を引張試験機のチャックにくわえて引っ張り、母材で破断したものを拡散接合性良好（○）、重ね面が剥がれたものを拡散接合性不良（×）として、Ｒａを横軸、Ｒｓｋを縦軸とする図１上にプロットした。その結果、Ｒａ≦０．４μｍで、かつＲａとＲｓｋとの関係が上記（１）式の関係にある場合には拡散接合性良好、そうでない場合には拡散接合性が不良となることがわかった。すなわちＲａが０．２μｍ超で拡散接合性の良好なものはＲｓｋが負でなければならず、Ｒａが０．２μｍ未満ならＲｓｋは若干は正であっても良いということになる。かくして表面粗度がＲａで０．０１μｍ以上０．２μｍ以下でかつＲａとＲｓｋとの関係が上記（１）式の関係にある箔、あるいは表面粗度がＲａで０．２μｍ超０．４μｍ以下でかつＲａとＲｓｋとの関係が上記（１）式の関係にある箔において、拡散接合性が良好であることが判った。
【００１７】
本発明においてＲａも上下限を設定した理由を説明する。Ｒａの下限の０．０１μｍは、これ未満のＲａのものは工業的につくりにくく、またメタル担体加工した後も触媒物質の担持工程でも問題を起こすので０．０１μｍをＲａの下限とした。またＲａが０．４μｍを超えると、Ｒｓｋがかなり大きな負であっても、さすがに表面凹凸が大きくなるので拡散接合性が悪くなってくるため０．４μｍをＲａの上限とした。
【００１８】
なお本発明の対象となる箔材は２０Ｃｒ−５Ａｌ鋼の他、メタル担体のハニカムに使用されるすべてのＣｒ−Ａｌ系ステンレス鋼、その他の耐熱合金製金属箔材などである。
【００１９】
【実施例】
（実施例１）
図１にプロットした箔のうち７種のものを幅１５０ｍｍの箔からさらに１２０ｍｍにスリットし、各箔の約６割のものをコルゲート加工して波箔を作成した。平箔とともに充分脱脂をしてから平箔と波箔を重ね、平箔に５ｋｇの後方張力を掛けながら円筒形に巻回し、７８ｍｍφのハニカムを作った。これを１９％Ｃｒステンレス鋼製の８１ｍｍφ×１．５ｍｍｔの外筒内に挿入し、その後これを８０ｍｍφにまで縮径した。このようにして各箔材についてメタル担体を作成し、これらに１２５０℃×３０分の真空熱処理を行い、拡散接合処理を行った。これらのメタル担体のハニカム部の外周部付近から１ｃｍキューブの試験材を切り出し、エポキシ系接着剤によりステンレス製の補助冶具に固定して、ハニカムの径方向に引張試験を行った。この際の最大荷重が１０ｋｇｆ以上のものは良品で、それ未満であれば接合不良と判定できることが経験的に判っている。
【００２０】
各箔のＲａ、Ｒｓｋとハニカムの引張強度と判定結果等を表１に示す。
【００２１】
【表１】

【００２２】
上表が示すように、ＲａとＲｓｋが本発明の要件を充たす本発明例のハニカムはいずれも高いハニカム強度を示し、本発明の要件を満たさない比較例のハニカムは低い接合強度を示した。
【００２３】
（実施例２）
実施例１で作られた試料番号Ａ，Ｃ，Ｇの箔を用いて、同様な方法でメタル担体を３個試作した。今回はエンジンベンチ試験で冷熱耐久試験を行うため、図５に示すように熱応力開放のための接合構造の作りこみを行った。すなわち、ハニカム１を巻回す際に、最外周層から３，４層目の波箔の波頂点でガス出側から９０ｍｍまでの部分に焼き付き防止剤を塗布して、熱処理後のハニカム内に非接合部４を導入した。またハニカム１を外筒２に挿入する前に、ガスの出側から４０ｍｍまでのハニカム外周面にロウ箔をスポット溶接し、それ以外の外周面には焼き付き防止剤を塗布した。これによりガス出側から４０ｍｍまでの間にハニカムと外筒間の接合部３が導入された。
【００２４】
かくして試作されたメタル担体の両側にコーンとフランジを溶接し、排気量が２０００ｃｃのエンジンのエキマニ直下に装着して、６０００回転でスロットル全開を３０分、エンジン停止３０分ファン冷却を６００回繰り返す冷熱耐久試験を各メタル担体について行った。試験は５０回ごとに内部を点検して、異常が無ければ試験を続行した。
【００２５】
その結果Ａの箔を用いて試作したメタル担体は、４５０回の点検時にハニカム内の非接合部４より内周部が、ガス出側に突出しているのが発見され、試験を中止した。これに対し、ＣおよびＧの箔を用いたメタル担体は６００回の点検時まで異常がなく、耐久試験に合格した。
【００２６】
【発明の効果】
以上に述べたように、本発明は拡散接合性の良いメタル担体用の金属箔とそれによるメタル担体を高い信頼性のもとに供給するものである。
【図面の簡単な説明】
【図１】箔の表面粗さＲａ（横軸）とＲｓｋ（縦軸）によって拡散接合性の良好なものと悪いものが区別できることを示す分布図。
【図２】Ｒａが０．２μｍ超でかつ拡散接合性の良い箔の典型的な輪郭曲線のパターンを示す図。
【図３】Ｒａが０．２μｍ以下でかつ拡散接合性の悪い箔の典型的な輪郭曲線のパターンを示す図。
【図４】箔の拡散接合性を簡便に評価するために、真空熱処理で箔を拡散接合させるための装置図。
【図５】拡散接合をして試作されたメタル担体の接合構造を示す断面図。
【符号の説明】
１ハニカム
２外筒
３ハニカム／外筒間の接合部
４ハニカム内の非接合部
１１評価する箔
１２接合部に荷重をかけるための錘
１３台座[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat resistant stainless steel foil used for a metal carrier for purifying automobile exhaust gas and a metal carrier using the foil.
[0002]
[Prior art]
As a catalytic converter for purifying automobile exhaust gas, a metal carrier using a heat-resistant steel foil as a honeycomb material has been increasingly important. Although the metal carrier is superior to the ceramic carrier in purifying exhaust gas, etc., the metal carrier is expensive and limited to some luxury vehicles. Therefore, efforts are made to reduce the cost of the metal carrier as much as possible. A metal carrier is usually manufactured by joining a flat foil and a corrugated foil by brazing, but a technique of producing by diffusion bonding without using an expensive brazing material is proposed in Patent Document 1, Patent Document 2, and the like. In the case of diffusion bonding, the diffusion bonding property depends on the surface roughness of the foil material. In Patent Document 3, the surface roughness of the honeycomb body (after diffusion bonding) is defined as an arithmetic average roughness Ra of 0.15 to 3 μm. It is disclosed that a catalyst support layer such as γ-alumina is suitably formed on a honeycomb body (after diffusion bonding). Patent Document 4 discloses that the surface roughness of a foil suitable for diffusion bonding is 0.1 to 0.3 with a 10-point average roughness Rz (former JIS).
[0003]
Furthermore, in Patent Document 5, it is clarified that Ra is a more accurate index than the maximum roughness Rmax of the old JIS and the ten-point average roughness Rz of the old JIS that affects the diffusion bonding property of the foil. The surface roughness of the foil having good diffusion bonding property was set to 0.001 to 0.2 μm in Ra.
[0004]
[Patent Document 1]
JP-A-1-270947 [Patent Document 2]
JP-A-2-14747 [Patent Document 3]
Japanese Utility Model Publication No. 3-102237 [Patent Document 4]
Japanese Patent Laid-Open No. 3-1188839 [Patent Document 5]
JP-A-8-38912
[Problems to be solved by the invention]
According to the invention described in Patent Document 5, it has become possible to provide a foil having good diffusion bonding properties that can be used in the production of a metal carrier. However, the durability of the metal carrier has been improved to further increase the reliability. In order to provide a metal carrier having a further improvement in diffusion bonding properties is required.
[0006]
An object of the present invention is to realize a further improvement in diffusion bonding property of a metal carrier foil material and to supply a metal carrier with high reliability.
[0007]
[Means for Solving the Problems]
In view of such problems, the present invention has pursued the relationship between the diffusion bonding property of the metal carrier foil material and the surface roughness thereof, and as a result, combined with the skewness Rsk of the contour curve in addition to Ra, the diffusion bonding property is extremely good. This is due to the fact that a new foil can be obtained.
[0008]
That is, according to the first aspect of the present invention, the diffusion bonding is characterized in that the surface roughness Ra is 0.32 μm or more and 0.4 μm or less, and the relationship between Ra and Rsk is expressed by the following formula (1). It is a heat-resistant stainless steel foil for a metal carrier for exhaust gas purification having good properties.
Rsk ≦ −10 × (Ra−0.2) (1)
[0009]
The second aspect of the present invention is an exhaust gas purifying metal carrier in which a honeycomb composed of a heat-resistant stainless steel foil is inserted into a heat-resistant stainless steel outer tube and diffusion-bonded. Is a metal carrier for purifying exhaust gas, characterized in that the above is within the scope of the first invention.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below. It has been disclosed in many documents that the diffusion bonding property of metal is better when the surface roughness is smaller, and is well known. In this case, the test material is a thin plate or a bar. In that case, the maximum roughness Rmax of the old JIS, the ten-point average roughness Rz of the old JIS, and the like have been used as indexes that influence the diffusion bonding property. The former measures the difference between the highest peak and the deepest valley bottom within the reference length, and the latter measures the average height of the highest peak from the highest peak to the fifth and the depth of the lowest valley to the fifth peak. The height of the difference from the average is measured. That is, these parameters represent the extreme values of surface roughness. The factor that affects the diffusion bonding property is the size of the area where the metal surfaces are brought into contact with each other with a small pressure. The larger the value, the better the diffusion bonding property. In the case of a relatively rigid material such as a thin plate or a bar, the extreme values of these surface roughnesses affect the contact state of the joint surface, so these parameters are good indicators of diffusion weldability.
[0011]
On the other hand, in the case of a soft material such as a foil, as described in Patent Document 5, since the material is deformed to some extent in the middle part between the peak and the peak that gives the extreme value, the joint surface becomes compatible with each other. It has been clarified that Ra representing the average degree of unevenness more accurately represents diffusion bonding than Rmax and Rz. From this result, in Patent Document 5, the surface roughness of the foil having good diffusion bonding property was set to 0.001 to 0.2 μm in Ra.
[0012]
Thereafter, while investigating many foils, it was newly discovered that the characteristics of the surface roughness of a foil having good diffusion bonding properties cannot be accurately grasped only by Ra. That is, it has been found that some foils within the Ra range defined in Patent Document 5 have poor diffusion bonding properties, and even those outside this range have good diffusion bonding properties.
[0013]
That is, when the typical contour curve of the foil is as shown in FIG. 2, the mountain portion has a relatively smooth plateau plateau shape, and there is a deep valley in some places. Even if the thickness is 0.2 μm or less or more than 0.2 μm, the diffusion bonding property is very good. As can be seen from these, Ra is slightly larger due to deep valleys in some parts, but these do not adversely affect diffusion bonding properties, and diffusion bonding properties are good if most of the peaks are smooth. It shows that. A foil with such a contour curve is obtained when a roller with a large surface roughness is used to increase the rolling reduction per pass and several efficient rollings are performed, and finally the finish rolling is performed with a roller having an extremely smooth surface. Turned out to be.
[0014]
Conversely, if the typical contour curve of the foil is as shown in FIG. 3, where there are relatively high peaks and where most of the valleys are smooth and the shape of the curve of FIG. 2 is upside down, It has been found that even if Ra is 0.2 μm or less, the above-described very good diffusion bonding property cannot be obtained. Such a foil often appears when rolled with a rolling roller immediately after overhaul. That is, when the surface of the damaged rolling roller is ground and further polished to smooth the surface, rolling with a roller in which a deep grinding iron remains remains, a foil having a contour curve as shown in FIG. 3 is obtained. In this case, although the diffusion bonding property is deteriorated by some peaks, Ra is affected by the smoothness of most valleys and becomes relatively small.
[0015]
From the above examination results, some deep valleys do not affect diffusion bonding, but some high peaks adversely affect. Therefore, the surface roughness parameter skewness Rsk (contour curve root-mean-square / root-mean-square ^3/2 dimensionless) that can be expressed by distinguishing the number of protruding peaks and steep valleys together with Ra is an evaluation criterion for diffusion bonding properties. It implies that it can be. That is, Rsk is a dimensionless value that is positive if there are many peaks protruding in the contour curve and negative if there are many steep valleys.
[0016]
The present inventors changed the surface finish of the rolling roller to several, rolled a 20 μm-5Al steel 50 μm foil to 30 μm, and polished the surface of the rolled foil with various kinds of emery paper. Thus, foils having various surface properties were obtained. Ra and Rsk of each foil thus obtained were measured with a surface roughness meter. In this case, the reference length was 0.8 mm, the stylus diameter was 2 μm, and the others were in accordance with JIS B 0601 (2001). Further, these foils were cut into two pieces each having a size of 100 L × 10 W, and as shown in FIG. 4, 10 L × 10 W at the tips of the foils 11 were overlapped with each other. The block 12 was placed on the base 13 and set so that a load of 90 g was applied, and vacuum heat treatment was performed at 1200 ° C. for 20 minutes. The degree of vacuum at 1200 ° C. was 2 to 5 × 10 ⁻⁵ Torr. After heat treatment, pull both ends of the foil together with the chuck of the tensile tester, break the base metal with good diffusion bondability (○), and peel off the overlapped surface with poor diffusion bondability (×). Plotted on FIG. 1 with the axis, Rsk as the vertical axis. As a result, it is understood that when Ra ≦ 0.4 μm and the relationship between Ra and Rsk is the relationship of the above formula (1), the diffusion bonding property is good, and otherwise, the diffusion bonding property is poor. It was. That is, if Ra is more than 0.2 μm and diffusion bonding is good, Rsk must be negative, and if Ra is less than 0.2 μm, Rsk may be slightly positive. Thus, a foil having a surface roughness Ra of 0.01 μm or more and 0.2 μm or less and a relationship between Ra and Rsk in the above formula (1), or a surface roughness Ra of 0.2 μm or more and 0.4 μm or less. In addition, it was found that in the foil in which the relationship between Ra and Rsk is the relationship of the above formula (1), the diffusion bonding property is good.
[0017]
In the present invention, the reason why Ra also sets the upper and lower limits will be described. The lower limit of Ra of 0.01 μm is less than that of Ra, which is difficult to produce industrially, and causes a problem in the process of supporting the catalyst material after processing the metal carrier, so 0.01 μm was set as the lower limit of Ra. Further, if Ra exceeds 0.4 μm, even if Rsk is very large negative, the surface unevenness is increased, so that the diffusion bonding property is deteriorated. Therefore, 0.4 μm is set as the upper limit of Ra.
[0018]
In addition to the 20Cr-5Al steel, the foil material that is the subject of the present invention is all Cr-Al stainless steel used for the honeycomb of the metal carrier, other heat-resistant alloy metal foil materials, and the like.
[0019]
【Example】
(Example 1)
Of the foils plotted in FIG. 1, seven types of foils were further slit from a foil with a width of 150 mm to 120 mm, and about 60% of each foil was corrugated to prepare corrugated foils. After thoroughly degreased together with the flat foil, the flat foil and the corrugated foil were overlapped and wound into a cylindrical shape while applying a rear tension of 5 kg to the flat foil to make a 78 mmφ honeycomb. This was inserted into an 81 mmφ × 1.5 mmt outer cylinder made of 19% Cr stainless steel, and then the diameter was reduced to 80 mmφ. In this way, metal carriers were prepared for the respective foil materials, and these were subjected to vacuum heat treatment at 1250 ° C. for 30 minutes to perform diffusion bonding treatment. A test material of 1 cm cube was cut out from the vicinity of the outer periphery of the honeycomb portion of these metal carriers, fixed to a stainless steel auxiliary jig with an epoxy adhesive, and a tensile test was performed in the radial direction of the honeycomb. It has been empirically known that a product with a maximum load of 10 kgf or more is a non-defective product, and if it is less than that, it can be judged as a joint failure.
[0020]
Table 1 shows the Ra, Rsk of each foil, the tensile strength of the honeycomb, the determination results, and the like.
[0021]
[Table 1]

[0022]
As shown in the above table, each of the honeycombs of the present invention in which Ra and Rsk satisfy the requirements of the present invention showed high honeycomb strength, and the honeycomb of the comparative example not satisfying the requirements of the present invention showed low bonding strength.
[0023]
(Example 2)
Using the foils of sample numbers A, C, and G made in Example 1, three metal carriers were manufactured in the same manner. In order to perform a cold endurance test in the engine bench test this time, as shown in FIG. 5, a joint structure for releasing the thermal stress was built. That is, when the honeycomb 1 is wound, an anti-seizing agent is applied to the portion from the gas outlet side to 90 mm at the wave top of the third and fourth corrugated foils from the outermost peripheral layer, and the honeycomb 1 after heat treatment The joint 4 was introduced. Further, before inserting the honeycomb 1 into the outer cylinder 2, a brazing foil was spot welded to the honeycomb outer peripheral surface from the gas outlet side to 40 mm, and an anti-seizure agent was applied to the other outer peripheral surface. Thereby, the joint part 3 between the honeycomb and the outer cylinder was introduced between 40 mm from the gas outlet side.
[0024]
Cone and flange are welded to both sides of the prototype metal carrier thus mounted, mounted directly under the exhaust manifold of the engine with a displacement of 2000cc, the throttle is fully opened at 6000 rpm for 30 minutes, the engine is stopped for 30 minutes, and the fan cooling is repeated 600 times An endurance test was performed on each metal carrier. The test was conducted every 50 times, and the test was continued if there was no abnormality.
[0025]
As a result, it was found that the metal carrier prototyped using the foil of A protruded from the non-bonded portion 4 in the honeycomb to the gas outlet side after 450 inspections, and the test was stopped. In contrast, the metal carrier using the C and G foils did not have any abnormality until 600 inspections, and passed the durability test.
[0026]
【The invention's effect】
As described above, the present invention supplies a metal foil for a metal carrier having a good diffusion bonding property and a metal carrier made thereby with high reliability.
[Brief description of the drawings]
FIG. 1 is a distribution diagram showing that good and bad diffusion bonding properties can be distinguished by foil surface roughness Ra (horizontal axis) and Rsk (vertical axis).
FIG. 2 is a diagram showing a typical contour curve pattern of a foil having Ra of more than 0.2 μm and good diffusion bonding properties.
FIG. 3 is a diagram showing a typical contour curve pattern of a foil having Ra of 0.2 μm or less and poor diffusion bonding property.
FIG. 4 is an apparatus diagram for performing diffusion bonding of a foil by vacuum heat treatment in order to easily evaluate the diffusion bonding property of the foil.
FIG. 5 is a cross-sectional view showing a joint structure of a metal carrier fabricated by diffusion bonding.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Honeycomb 2 Outer cylinder 3 Joining part between honeycombs / outer cylinders 4 Non-joining part 11 in the honeycomb 11 Foil 12 to be evaluated 13 Weight for applying load to the joining part 13 Base

Claims

Surface roughness is 0.32μm or more 0.4μm or less in Ra, and Ra and relationship between the Rsk is below (1) the metal carrier for a good exhaust gas purification of the diffusion bondability, characterized in that a relation of Heat resistant stainless steel foil.
Rsk ≦ −10 × (Ra−0.2) (1)

In the exhaust gas purifying metal carrier which is diffusion bonded by inserting a honeycomb made of heat resistant stainless steel foil into an outer tube made of heat resistant stainless steel, the surface roughness of the stainless steel foil is within the range of claim 1. A metal carrier for exhaust gas purification characterized by the above.