JP5388084B2 - Aluminum alloy clad material for heat exchangers with excellent strength and pitting corrosion resistance - Google Patents
Aluminum alloy clad material for heat exchangers with excellent strength and pitting corrosion resistance Download PDFInfo
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- JP5388084B2 JP5388084B2 JP2007196010A JP2007196010A JP5388084B2 JP 5388084 B2 JP5388084 B2 JP 5388084B2 JP 2007196010 A JP2007196010 A JP 2007196010A JP 2007196010 A JP2007196010 A JP 2007196010A JP 5388084 B2 JP5388084 B2 JP 5388084B2
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- 238000005260 corrosion Methods 0.000 title claims description 91
- 239000000463 material Substances 0.000 title claims description 91
- 230000007797 corrosion Effects 0.000 title claims description 88
- 229910000838 Al alloy Inorganic materials 0.000 title claims description 44
- 239000010405 anode material Substances 0.000 claims description 67
- 238000005219 brazing Methods 0.000 claims description 62
- 239000011162 core material Substances 0.000 claims description 34
- 239000011856 silicon-based particle Substances 0.000 claims description 25
- 239000012535 impurity Substances 0.000 claims description 11
- 239000011159 matrix material Substances 0.000 claims description 10
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- 229910052725 zinc Inorganic materials 0.000 description 5
- 229910018125 Al-Si Inorganic materials 0.000 description 4
- 229910018520 Al—Si Inorganic materials 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
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Description
本発明は、フラックスを用いる不活性ガス雰囲気ろう付や真空ろう付により製造される自動車用のラジエーター、ヒーターコアなどのアルミニウム製熱交換器の構造部材として適用でき、特に優れたろう付性や耐孔食性が要求される薄肉のチューブ材として最適に使用できる強度および耐孔食性に優れる熱交換器用アルミニウム合金クラッド材に関するものである。 INDUSTRIAL APPLICABILITY The present invention can be applied as a structural member for aluminum heat exchangers such as radiators for automobiles and heater cores manufactured by inert gas atmosphere brazing and vacuum brazing using flux, and has particularly excellent brazing properties and hole resistance. The present invention relates to an aluminum alloy clad material for a heat exchanger that is excellent in strength and pitting corrosion resistance that can be optimally used as a thin-walled tube material that requires corrosion resistance.
自動車用熱交換器の一種であるラジエーターは、一般にフィン、チューブ、ヘッダー、サイドサポートなどの部材をフッ化物系フラックスを使用するろう付接合によって一体化され、製造される。
チューブ材としては、Ａｌ−Ｍｎ−Ｃｕ系合金からなる芯材の片面にＡｌ−Ｓｉ系ろう材をクラッドし、他の片面に犠牲陽極材としてＡｌ−ＺｎもしくはＡｌ−Ｍｇ−Ｚｎ系合金をクラッドした３層のアルミニウム合金が使用されている。最も一般的に用いられている前記クラッド材合金としては、ＪＩＳ３００３合金（質量％でＭｎ：１．０〜１．５％、Ｃｕ：０．１〜０．２％、Ｓｉ：０．６％以下、Ｆｅ：０．７５％以下、Ｚｎ：０．１０％以下、残部：Ａｌおよび不可避不純物からなるＡｌ−Ｍｎ系合金）を芯材とし、この芯材の片面にＪＩＳ７０７２合金からなる犠牲陽極材を貼り合わせ、他方の片面にＡｌ−Ｓｉ系あるいはＡｌ−Ｓｉ−Ｚｎ系ろう材を貼り合わせたクラッド材（ブレージングシート）が知られている。Ａｌ−Ｓｉ系ろう材は、ろう付時にチューブ材とフィン材の接合、およびチューブ材とヘッダープレートとの接合に用いられ、犠牲陽極材は熱交換器として使用中に作動流体と接して芯材との電気化学的性質の違いにより皮材が主として腐食する犠牲陽極効果を発揮し、芯材の孔食や隙間腐食の発生を抑制し、耐孔食性を向上させる作用を有する。
A radiator, which is a type of heat exchanger for automobiles, is generally manufactured by integrating members such as fins, tubes, headers, and side supports by brazing using a fluoride-based flux.
As a tube material, an Al—Si brazing material is clad on one surface of a core material made of an Al—Mn—Cu alloy, and Al—Zn or Al—Mg—Zn alloy is clad as a sacrificial anode material on the other surface. A three-layer aluminum alloy is used. The most commonly used clad alloy is JIS3003 alloy (Mn: 1.0 to 1.5%, Cu: 0.1 to 0.2%, Si: 0.6% or less in mass%). Fe: 0.75% or less, Zn: 0.10% or less, balance: Al—Mn alloy composed of Al and inevitable impurities) as a core material, and a sacrificial anode material composed of JIS7072 alloy on one side of the core material. A clad material (brazing sheet) is known in which an Al—Si or Al—Si—Zn brazing material is bonded to the other surface. The Al-Si brazing material is used for joining the tube material and the fin material, and joining the tube material and the header plate at the time of brazing, and the sacrificial anode material is in contact with the working fluid during use as a heat exchanger and is a core material. The sacrificial anode effect in which the skin material mainly corrodes due to the difference in electrochemical properties with the above has an effect of suppressing pitting corrosion and crevice corrosion of the core material and improving pitting corrosion resistance.
近年、自動車用熱交換器は軽量化および小型化によるコストの低減や高性能化を達成するため構成部材には一層の薄肉化が要求されている。チューブ材が薄肉化すると高周波溶接によるチューブ造管が困難となるため、今後はろう付により造管を行なうチューブが主流となると考えられる（特許文献１、２参照）。該造管の例を図２により説明すると、ろう材１２と犠牲陽極材１３とを芯材１１のそれぞれ片面にクラッドしたクラッド材１０を犠牲陽極材１３が内側になるように曲げるとともに、両端をそれぞれ内側に折り込んで互いに当接して内柱部１５を設け、該円柱部１５の先端を犠牲陽極材１３に突き当てて、ろう付けを行って管にするものである。
2. Description of the Related Art In recent years, automotive heat exchangers are required to have thinner components in order to achieve cost reduction and high performance by reducing weight and size. If the tube material is thinned, it becomes difficult to make a tube by high-frequency welding, so that it is considered that a tube that is formed by brazing will become the mainstream in the future (see
しかし、この場合、チューブ造管形状の違いや材料の薄肉化に伴い上記のブレージングシートを使用してもチューブ内柱部近傍Ａで接合不良が多発し、期待通りの耐久・耐圧強度が得られないことが問題となっている。そこで、チューブ内柱部近傍においても良好な接合が得られるクラッド材が求められている。 However, in this case, due to the difference in tube tube shape and thinning of the material, even if the above brazing sheet is used, joint failure frequently occurs in the vicinity A of the column in the tube, and the expected durability and pressure strength can be obtained. There is no problem. Therefore, a clad material that can obtain good bonding even in the vicinity of the column in the tube is required.
また、アルミニウム合金の表面は通常自然酸化皮膜で覆われおり、中性の水溶液環境では耐食性に優れていることから、自動車用の熱交換器の冷媒流通経路材として用いられている。しかし、この酸化皮膜が何らかの原因で局部的に破壊されると、他の部分が強固なため皮膜欠陥部に腐食が集中して孔食が発生し、早期に貫通孔が生じるという欠点がある。この対策としてラジエーターなどの自動車熱交換器では上記のように芯材の片面に芯材よりも電気的に卑なアルミニウム合金を犠牲陽極材として張り合わせたクラッド材が用いられている。 Moreover, since the surface of an aluminum alloy is usually covered with a natural oxide film and is excellent in corrosion resistance in a neutral aqueous solution environment, it is used as a refrigerant flow path material for a heat exchanger for automobiles. However, when this oxide film is locally broken for some reason, the other part is strong, so that corrosion concentrates on the defective part of the film, resulting in pitting corrosion, and a through hole is formed at an early stage. As a countermeasure, an automobile heat exchanger such as a radiator uses a clad material in which an aluminum alloy that is electrically lower than the core material is bonded to one side of the core material as a sacrificial anode material as described above.
これらのアルミニウム合金クラッド材は、ラジエーターやヒーターコアなどのアルミニウム製熱交換器の冷媒流通経路材として使用された場合、冷媒が中性〜弱酸性でＣｌイオンを含む溶液の時には優れた犠牲陽極効果を発揮するが、冷媒がｐＨ９以上のアルカリ性溶液の場合には、犠牲陽極材の効果が働かずに短期間で貫通孔が発生し、防食効果が十分に発揮されないことが問題となっている。 These aluminum alloy clad materials have excellent sacrificial anode effect when used as a refrigerant flow path material for aluminum heat exchangers such as radiators and heater cores, when the refrigerant is neutral to weakly acidic and contains Cl ions. However, when the refrigerant is an alkaline solution having a pH of 9 or more, the effect of the sacrificial anode material does not work and a through hole is generated in a short period of time, so that the anticorrosion effect is not sufficiently exhibited.
そこで、アルカリ環境中で耐孔食性を向上させたアルミニウム合金クラッド材として、例えば、Ｓｉ：０．６％以下、Ｆｅ：０．７％以下、Ｃｕ：０．０５〜０．２０％、Ｍｎ：１．０〜１．５％、Ｚｎ：０．１０％以下の元素を含み、残部が不可避不純物元素およびＡｌからなるアルミニウム合金芯材の片面にＡｌ−Ｓｉ系合金ろう材をクラッドし、他方の片面にＦｅ：０．７〜１．２％、Ｚｎ：０．１〜１．５％を含むアルミニウム合金犠牲陽極材をクラッドした３層のアルミニウム合金クラッド材が提案されている（特許文献３参照）。 Therefore, as an aluminum alloy clad material with improved pitting corrosion resistance in an alkaline environment, for example, Si: 0.6% or less, Fe: 0.7% or less, Cu: 0.05-0.20%, Mn: Al-Si alloy brazing material is clad on one side of an aluminum alloy core material containing elements of 1.0 to 1.5%, Zn: 0.10% or less, and the balance being inevitable impurity elements and Al, A three-layer aluminum alloy clad material is proposed in which an aluminum alloy sacrificial anode material containing Fe: 0.7 to 1.2% and Zn: 0.1 to 1.5% is clad on one surface (see Patent Document 3). ).
また、アルミニウム合金よりなる芯材の片面にアルミニウム合金ろう材をクラッドし、他の面に犠牲陽極材をクラッドしたアルミニウム合金クラッド材において、犠牲陽極材がＡｌと結合して犠牲陽極材のマトリックスより貴な化合物を生成する元素を含有し、残部Ａｌおよび不純物からなるアルミニウム合金から構成され、マトリックス中に粒子径（円相当直径、以下同じ）１〜１０μｍの前記化合物が１ｍｍ２当たり５×１０２〜５×１０４個存在することを特徴とする耐食性に優れた熱交換器用アルミニウム合金クラッド材も提案されている（特許文献４参照）。
しかし、上記材料は犠牲陽極材中にマトリックスより電位が貴な化合物が多数存在するため、局部セルの形成により犠牲陽極材の腐食速度が増大し、腐食生成物によるラジエータチューブの目詰まりが問題となる。また、従来はクラッド材の耐孔食性向上のみを考慮しており、ろう付性向上については十分とはいえない。特に薄肉材の場合、ろう付で造管するチューブでは、さらなるろう付性の向上が必要となる。 However, since the above materials contain many compounds having a higher potential than the matrix in the sacrificial anode material, the corrosion rate of the sacrificial anode material increases due to the formation of local cells, and clogging of the radiator tube due to corrosion products is a problem. Become. Conventionally, only the improvement of pitting corrosion resistance of the clad material is considered, and it cannot be said that the improvement of brazing is sufficient. Particularly in the case of a thin-walled material, it is necessary to further improve the brazing property in a tube that is formed by brazing.
本発明は、上記事情を背景としてなされたものであり、薄肉材でも優れたろう付性を有し、なおかつ酸性からアルカリ環境までの幅広いｐＨ領域で優れた耐孔食性を有する材料を提供することを目的とする。 The present invention has been made against the background of the above circumstances, and provides a material having excellent brazing resistance even in a thin-walled material and having excellent pitting corrosion resistance in a wide pH range from acidic to alkaline environments. Objective.
発明者らは優れたろう付性と酸性からアルカリにおける幅広いｐＨ領域で優れた耐孔食性向上を有するクラッド材を得るべく研究を行なった結果、以下の知見を得た。 As a result of researches to obtain a clad material having excellent brazing resistance and excellent pitting corrosion resistance in a wide pH range from alkaline to excellent brazing and acidity, the inventors have obtained the following knowledge.
＜ろう付性＞
ろう付性については犠牲陽極材中にＳｉ粒子が微細に分布していると、これらが犠牲陽極材表面の酸化皮膜欠陥部を形成するため、フラックスにより酸化皮膜が十分に除去されない場合でもチューブ自身のろう材との濡れ性が向上し、良好な接合状態が得られる。また、Ｓｉ粒子近傍のマトリックスはろう付熱処理時のＳｉ拡散により低融点化し、ろう材との接合性が向上することを見出すに至った。この効果はＳｉの単独析出によるものであり、ＳｉはＦｅやＭｎ等と金属間化合物を形成しやすいため、これらの元素の添加量をコントロールし、Ｓｉ単独析出が十分に起こる添加量のバランスを考慮することが必要となる。
<Brassability>
As for brazing, if the Si particles are finely distributed in the sacrificial anode material, these form oxide film defects on the surface of the sacrificial anode material, so even if the oxide film is not sufficiently removed by the flux, the tube itself The wettability with the brazing filler metal is improved, and a good bonding state is obtained. In addition, the matrix in the vicinity of the Si particles has a low melting point due to Si diffusion during the brazing heat treatment, and it has been found that the bondability with the brazing material is improved. This effect is due to the single precipitation of Si. Since Si easily forms intermetallic compounds with Fe, Mn, etc., the addition amount of these elements is controlled, and the balance of the addition amount at which the single precipitation of Si occurs sufficiently. It is necessary to consider.
＜耐食性＞
従来は犠牲陽極材にＺｎを添加し、芯材に対して電位を卑にすることで深い孔食の発生を抑制していた。しかし、薄肉材の場合は、ろう付時の元素拡散により芯材との電位差が小さくなり犠牲陽極材の腐食形態が面状とならず部分的に深い孔食が発生してしまうことがあった。そこで、本発明材は犠牲陽極材にＳｉを添加することでＳｉ粒子を微細分散させ、犠牲陽極材の腐食発生起点を増加させることで、深い孔食の発生を抑制した。
<Corrosion resistance>
Conventionally, the generation of deep pitting corrosion has been suppressed by adding Zn to the sacrificial anode material and lowering the potential relative to the core material. However, in the case of thin-walled materials, the potential difference with the core material becomes small due to element diffusion during brazing, and the corrosion form of the sacrificial anode material does not become planar, and partial pitting corrosion may occur. . Therefore, the present invention material suppresses the occurrence of deep pitting corrosion by adding Si to the sacrificial anode material to finely disperse Si particles and increasing the corrosion starting point of the sacrificial anode material.
アルカリ環境における孔食は材料表面の皮膜欠陥部が優先的に腐食し、深い孔食が発生するものである。そこで、アルカリ環境中での耐孔食性を向上させるには皮膜欠陥部が局部的に集中するのを防ぎ、腐食の起点を材料表面全体に分散させる必要がある。そこで、本発明材では犠牲陽極材にＳｉを適量添加し、ろう付後に犠牲陽極材マトリックス中にＳｉ粒子が微細析出することによる耐孔食性の向上を図った。Ｓｉ析出物は皮膜の欠陥部を形成し、同部位が腐食の起点となるため局部的な腐食の発生を抑制し、腐食形態を面状にする効果がある。
犠牲陽極材にＦｅやＮｉを添加した場合もＡｌ−Ｆｅ、Ａｌ−Ｎｉ系の金属間化合物が生成し、アルカリ環境中において耐孔食性の向上効果は見られるが、そのサイズはＳｉ単独析出の場合に比べ非常に粗大となる。分散粒子の大きさはできるだけ小さい方が腐食の起点が増加し、腐食形態が面状となるため上記粗大金属間化合物を生成しないようにＳｉとＦｅ添加量のバランスを最適化することが重要である。
Pitting corrosion in an alkaline environment preferentially corrodes film defects on the material surface, resulting in deep pitting corrosion. Therefore, in order to improve the pitting corrosion resistance in an alkaline environment, it is necessary to prevent the coating defects from being concentrated locally and to disperse the starting point of corrosion over the entire material surface. Therefore, in the present invention material, an appropriate amount of Si was added to the sacrificial anode material, and the pitting corrosion resistance was improved by fine precipitation of Si particles in the sacrificial anode material matrix after brazing. The Si precipitate forms a defective portion of the film, and the same site serves as a starting point of corrosion, so that local corrosion is suppressed and the corrosion form is planarized.
When Fe or Ni is added to the sacrificial anode material, Al—Fe and Al—Ni-based intermetallic compounds are produced, and an effect of improving pitting corrosion resistance is seen in an alkaline environment, but the size is determined by the precipitation of Si alone. It is very coarse compared to the case. It is important to optimize the balance of Si and Fe addition amounts so that the coarse intermetallic compound is not generated because the starting point of corrosion increases and the corrosion form becomes planar when the size of the dispersed particles is as small as possible. is there.
また、Ｓｉ析出物は半導体であり、マトリックスと局部セルをほとんど形成しないため、Ａｌとの金属間化合物に比べ、腐食速度を増大させる作用は非常に小さく、チューブ目詰まりが抑制される。さらにＳｉ分散粒子はアルカリ溶液中で溶解しないため、腐食が進行するとそれらが材料表面に生成する皮膜中に取り込まれ皮膜を緻密かつ均一にする効果を有し、皮膜の密着性が向上するため材料表面への腐食液の侵入を防ぎ、腐食の進行速度を著しく抑制する効果がある。 Further, since the Si precipitate is a semiconductor and hardly forms a matrix and local cells, the action of increasing the corrosion rate is very small compared to an intermetallic compound with Al, and clogging of the tube is suppressed. Furthermore, since the Si-dispersed particles do not dissolve in an alkaline solution, when corrosion progresses, they are incorporated into the film formed on the surface of the material and have an effect of making the film dense and uniform, and the adhesion of the film is improved. It has the effect of preventing the intrusion of the corrosive liquid into the surface and remarkably suppressing the progress of corrosion.
以上のように、本発明者らは、ろう付け性および耐孔食性向上の観点から、犠牲陽極材中にＳｉ粒子が微細分散する優位性を見出し、犠牲陽極材の添加成分と添加量のバランス、その粒子サイズや分布状態を規定することでろう付性と耐孔食性の著しい改善を図っている。 As described above, the present inventors have found the superiority of fine dispersion of Si particles in the sacrificial anode material from the viewpoint of improving brazeability and pitting corrosion resistance, and the balance between the additive components and the addition amount of the sacrificial anode material. By defining the particle size and distribution state, brazing and pitting corrosion resistance are remarkably improved.
すなわち、本発明の強度および耐孔食性に優れるアルミニウム合金クラッド材のうち、第１の本発明は、アルミニウム合金芯材の片面にアルミニウム合金ろう材がクラッドされ、前記芯材の他方の片面に犠牲陽極材がクラッドされたアルミニウム合金クラッドにおいて、前記犠牲陽極材は、質量％で、Ｚｎ：０．５〜１０．０％、Ｓｉ：０．８〜１．５％、Ｍｇ：０．００５〜０．２％を含み、残部がＡｌと不可避不純物からなるとともに、前記不可避不純物中のＦｅと前記Ｓｉ量の割合がＦｅ量（ｗｔ％）≦１／４×Ｓｉ量（ｗｔ％）の関係を満足し、かつ、マトリックス中に円相当径で０．１〜１．０μｍのＳｉ粒子が１ｍｍ２当たり１５０００〜３×１０５個分布していることを特徴とする。 That is, among the aluminum alloy clad materials excellent in strength and pitting corrosion resistance of the present invention, the first present invention is such that an aluminum alloy brazing material is clad on one surface of the aluminum alloy core material and the other surface of the core material is sacrificed. In the aluminum alloy clad in which the anode material is clad, the sacrificial anode material is in mass%: Zn: 0.5 to 10.0%, Si: 0.8 to 1.5%, Mg: 0.005 to 0 .2%, the balance is made of Al and inevitable impurities, and the proportion of Fe and Si in the inevitable impurities satisfies the relationship of Fe amount (wt%) ≦ ¼ × Si amount (wt%). In addition, it is characterized in that 15,000 to 3 × 10 5 Si particles having an equivalent circle diameter of 0.1 to 1.0 μm are distributed in 1 mm 2 in the matrix.
第２の本発明の強度および耐孔食性に優れるアルミニウム合金クラッド材は、前記第１の本発明において、前記犠牲陽極材は、さらに質量％で、Ｎｉ：０．１〜１．５％を含むことを特徴とする。 Aluminum alloy clad material having excellent strength and pitting corrosion resistance of the second present invention, in the first aspect of the present invention, the sacrificial anode material is a further mass%, Ni: containing 0.1 to 1.5% It is characterized by that.
第３の本発明の強度および耐孔食性に優れるアルミニウム合金クラッド材は、前記第１または第２の本発明のいずれかにおいて、前記犠牲陽極材は、さらに質量％で、Ｔｉ：０．０５〜０．３％、Ｚｒ：０．０５〜０．３％のうち１種または２種以上を含むことを特徴とする。 Aluminum alloy clad material having excellent strength and pitting corrosion resistance of the third invention, in any one of the first or second invention, wherein the sacrificial anode material is a further mass%, Ti: 0.05 to One or more of 0.3% and Zr: 0.05 to 0.3% are included.
本発明では、上記のように犠牲陽極材各元素の含有量やその割合、Ｓｉ粒子のサイズと分布を制御し、犠牲陽極材中にＳｉ粒子を単独析出させることで、優れたろう付性と耐孔食性を確保している。以下に、犠牲陽極材中の合金成分の意義および成分範囲限定理由を記載する。なお、以下の含有量はいずれも質量％で示されている。 In the present invention, as described above, the content and ratio of each element of the sacrificial anode material, the size and distribution of the Si particles are controlled, and the Si particles are precipitated alone in the sacrificial anode material, thereby achieving excellent brazing and resistance. Ensures pitting corrosion. The significance of the alloy component in the sacrificial anode material and the reason for limiting the component range are described below. In addition, all the following contents are shown by the mass%.
Ｚｎ：０．５〜１０．０％
Ｚｎは犠牲陽極材の電位を卑にし、芯材に対する犠牲陽極効果を効果的なものにするため、芯材に腐食が進行するのを防止する。また、犠牲陽極材表面の酸化皮膜を脆弱にし、腐食の発生起点を増加させて腐食形態を面状にする効果もある。その含有量が０．５％未満では酸性域で所望の効果が得られず、一方、１０．０％を超えて含有すると自己耐食性が増大し過ぎて好ましくない。したがって、Ｚｎ含有量は０．５〜１０．０％に定めた。Ｚｎ含有量の一層好ましい下限は１．０％、同じく上限は５．０％である。
Zn: 0.5 to 10.0%
Zn lowers the potential of the sacrificial anode material and makes the sacrificial anode effect on the core material effective, thus preventing the corrosion of the core material. It also has the effect of making the oxide film on the surface of the sacrificial anode material brittle and increasing the starting point of corrosion to make the corrosion form planar. If the content is less than 0.5%, the desired effect cannot be obtained in the acidic region. On the other hand, if the content exceeds 10.0%, the self-corrosion resistance is excessively increased, which is not preferable. Therefore, the Zn content is set to 0.5 to 10.0%. The more preferable lower limit of the Zn content is 1.0%, and the upper limit is 5.0%.
Ｓｉ：０．８〜１．５％
Ｓｉは犠牲陽極材中にＳｉ粒子として分散し、Ｓｉ粒子が存在する部位は酸化皮膜の生成が抑制され、皮膜欠陥部を生じるため、ろう付時にろう材との濡れ性すなわち接合性が向上する。また、ろう付後に素地中に微細分散し、腐食の起点が増加するため、耐孔食性を向上させる。さらに、微細析出やマトリックスに固溶して強度を向上させる作用を有し、犠牲陽極材の強度向上に寄与する。Ｓｉ：０．８％未満では析出する分散粒子の数が少なくなるため所望の効果が得られず、一方、１．５％を超えると、融点が低下するためろう付け時に犠牲陽極材が局部溶融し、さらにＳｉ析出物のサイズや数が多くなり、かえって耐食性が低下する。したがって、Ｓｉ量を０．８〜１．５％に定めた。Ｓｉ含有量の一層好ましい下限は０．９％、同じく上限は１．２％である。
Si: 0.8 to 1.5%
Si is dispersed as Si particles in the sacrificial anode material, and the site where the Si particles are present suppresses the formation of an oxide film, resulting in a film defect, thereby improving the wettability, that is, the bondability with the brazing material during brazing. . Moreover, since it is finely dispersed in the substrate after brazing and the starting point of corrosion increases, the pitting corrosion resistance is improved. Furthermore, it has the effect of improving the strength by solid solution in fine precipitation or matrix, and contributes to the strength improvement of the sacrificial anode material. When Si is less than 0.8%, the desired effect cannot be obtained because the number of precipitated dispersed particles is small. On the other hand, when it exceeds 1.5%, the melting point is lowered and the sacrificial anode material is locally melted during brazing. In addition, the size and number of Si precipitates increase, and the corrosion resistance decreases. Therefore, the Si content is set to 0.8 to 1.5%. The more preferable lower limit of the Si content is 0.9%, and the upper limit is 1.2%.
Ｍｇ：０．００５〜０．２％
Ｍｇはろう付時に固溶し、材料強度を向上させる。また、ろう付後に犠牲陽極材中のＺｎ、ＳｉとＭｇＺｎ２、Ｍｇ２Ｓｉを形成し、時効硬化によりさらなる強度向上に寄与する。Ｍｇは、その含有量が０．００５％未満では所望の効果が得られず、０．２％を超えて含有するとろう付性が低下する。したがって、Ｍｇ添加量は０．００５〜０．２％の範囲に定めた。Ｍｇ含有量の一層好ましい下限は０．０３％、同じく上限は０．１５％である。
Mg: 0.005-0.2%
Mg dissolves during brazing and improves material strength. In addition, Zn, Si, MgZn 2 , and Mg 2 Si in the sacrificial anode material are formed after brazing and contribute to further strength improvement by age hardening. If the content of Mg is less than 0.005%, the desired effect cannot be obtained, and if it exceeds 0.2%, the brazing property decreases. Therefore, the Mg addition amount is set in the range of 0.005 to 0.2%. The more preferable lower limit of the Mg content is 0.03%, and the upper limit is 0.15%.
Ｆｅ量≦１／４×Ｓｉ量
ＦｅはＳｉとＡｌ−Ｆｅ−Ｓｉ系化合物を生成し、アルカリ環境中においてはこれらの金属開化合物を起点としてピットが発生し、孔食の起点を増加させる作用がある。ただし、Ｓｉ分散粒子に比べ粗大な化合物が形成されるため大きな孔食が発生しやすく、マトリックスと局部セルを形成しやすいため腐食速度も増加する。本発明においてはＳｉの析出が阻害され、かえって耐孔食性が低下するため、Ｓｉ含有量とのバランスによりＦｅ量を規制する。
Fe amount ≦ 1/4 × Si amount Fe generates Si and Al—Fe—Si based compounds, and in an alkaline environment, pits are generated starting from these metal opening compounds, thereby increasing the starting point of pitting corrosion. There is. However, since a coarser compound is formed as compared with Si-dispersed particles, large pitting corrosion is likely to occur, and since a matrix and local cells are easily formed, the corrosion rate is also increased. In the present invention, the precipitation of Si is inhibited, and the pitting corrosion resistance is lowered. Therefore, the Fe amount is regulated by the balance with the Si content.
すなわち、上記のように本発明では犠牲陽極材中にＳｉ単体粒子を析出させることが重要だが、ＳｉはＦｅと金属間化合物を生成しやすいため、Ｓｉ添加量に対するＦｅ添加量を制限する必要があり、本発明ではＦｅ量（ｗｔ％）≦１／４×Ｓｉ量（ｗｔ％）と規定した。犠牲陽極材中のＦｅ量が添加Ｓｉ量の１／４より多い場合は、Ａｌ−Ｆｅ−Ｓｉ系化合物が生成し、Ｓｉ単独析出量が低下するため、十分な効果を得ることが出来ない。 That is, as described above, it is important to precipitate Si single particles in the sacrificial anode material in the present invention, but since Si easily generates an intermetallic compound with Fe, it is necessary to limit the amount of Fe added to the amount of Si added. In the present invention, Fe amount (wt%) ≦ 1/4 × Si amount (wt%) is defined. When the amount of Fe in the sacrificial anode material is more than 1/4 of the amount of added Si, an Al—Fe—Si based compound is generated and the amount of precipitated Si alone is reduced, so that a sufficient effect cannot be obtained.
Ｎｉ：０．１〜１．５％
Ｎｉは素地中にＡｌ−Ｎｉ系化合物を生成するため、そこを起点として材料表面にピットが発生し、孔食の起点を増加させ深い孔食の発生を抑制するので所望により含有させる。特にアルカリ環境中ではカソード点の集中を抑制し、耐食性の向上に寄与する。また、強度の向上にも寄与する。Ａｌ−Ｎｉ系化合物はＳｉ粒子に比べると粗大だが、Ａｌ−Ｆｅ系化合物やＡｌ−Ｆｅ−Ｓｉ系化合物に比べるとその大きさが小さく均一に分布するため、耐食性向上に及ぼす効果が大きい。また、Ｓｉの析出物を微細に分布させる効果もある。Ｎｉは、その含有量が０．１％未満では所望の効果が得られず、一方、１．５％を超えて含有すると犠牲陽極皮材の自己腐食性が増大するので好ましくない。したがって、Ｎｉを所望に含有させる場合、その含有量を０．１％〜１．５％の範囲に定めた。Ｎｉ含有量の一層好ましい下限は０．３％であり、同じく上限は０．７％である。
Ni: 0.1 to 1.5%
Ni forms an Al—Ni-based compound in the substrate. Therefore, pits are generated on the material surface starting from the Ni-Ni compound, and the starting point of pitting corrosion is increased to suppress deep pitting corrosion. In particular, in an alkaline environment, the concentration of cathode spots is suppressed, contributing to improvement in corrosion resistance. It also contributes to the improvement of strength. Al—Ni-based compounds are coarser than Si particles, but compared to Al—Fe-based compounds and Al—Fe—Si-based compounds, their size is small and evenly distributed, so that they have a great effect on improving corrosion resistance. In addition, there is an effect of finely distributing Si precipitates. If the Ni content is less than 0.1%, the desired effect cannot be obtained. On the other hand, if it exceeds 1.5%, the self-corrosion property of the sacrificial anode skin material is increased, which is not preferable. Therefore, when Ni is contained as desired, the content is set in the range of 0.1% to 1.5%. The more preferable lower limit of the Ni content is 0.3%, and the upper limit is 0.7%.
Ｔｉ：０．０５〜０．３％
Ｚｒ：０．０５〜０．３％
Ｔｉを添加すると鋳造時にＴｉ濃度（固溶度）が高い部分と低い部分が生成し、これが圧延時に延ばされ材料中に層状のＴｉ濃度分布が形成されるので所望により含有させる。Ｔｉ濃度が低い部分は高い部分に比べ電位が卑になり、優先的に腐食が進行するため腐食形態が層状となり耐食性が向上する。また、Ｚｒを添加するとＡｌ−Ｚｒ系の金属間化合物が微細に析出し、それらがアルカリ環境中で腐食の起点となり、孔食の発生数を増加させ、深い孔食の発生を抑制する。ＺｒにはＴｉの層状腐食を促進する作用があり、ＴｉとＺｒを同時に添加するとさらに耐孔食性を向上させる効果がある。
Ti: 0.05-0.3%
Zr: 0.05-0.3%
When Ti is added, a portion having a high Ti concentration (solid solubility) and a portion having a low Ti content are produced during casting, and this is extended during rolling to form a layered Ti concentration distribution in the material. The portion where the Ti concentration is low has a lower potential than the portion where the Ti concentration is high, and corrosion progresses preferentially, so that the corrosion form becomes layered and the corrosion resistance is improved. In addition, when Zr is added, Al—Zr-based intermetallic compounds are finely precipitated, which serve as starting points of corrosion in an alkaline environment, increase the number of pitting corrosion, and suppress the occurrence of deep pitting corrosion. Zr has the effect of promoting the layered corrosion of Ti, and when Ti and Zr are added simultaneously, it has the effect of further improving the pitting corrosion resistance.
これらの成分は、ろう付後に微細な金属間化合物として素地中に分散し、強度を向上させる作用を有するので必要に応じて添加するが、Ｔｉ：０．０５％未満、Ｚｒ：０．０５％未満では所望の効果が得られず、一方、Ｔｉ：０．３％、Ｚｒ：０．３％を超えて含有させると、加工性が低下するので好ましくない。したがって、Ｔｉ：０．０５〜０．３％、Ｚｒ：０．０５〜０．３％の範囲に定めた。 These components are dispersed in the substrate as a fine intermetallic compound after brazing and have an effect of improving the strength, so that they are added as necessary, but Ti: less than 0.05%, Zr: 0.05% If it is less than the range, the desired effect cannot be obtained. On the other hand, if it exceeds Ti: 0.3% and Zr: 0.3%, the workability is lowered, which is not preferable. Therefore, Ti: 0.05 to 0.3% and Zr: 0.05 to 0.3% were set.
＜Ｓｉ粒子のサイズと数の規定＞
０．１〜１．０μｍのＳｉ粒子：３×１０２〜３×１０５個／ｍｍ２
犠牲陽極材表面のＳｉ粒子が存在する部位は酸化皮膜の生成が抑制され、皮膜欠陥部を生じると共に、ろう付温度ではＳｉ粒子近傍のマトリックスがＳｉ拡散により低融点化し、ろう材との濡れ性が向上し、チューブ内柱部の接合性が向上する。また、Ｓｉ粒子は酸化皮膜の欠陥部を生成するため、その周りが腐食の発生起点となり、腐食形態を面状にする。本発明の範囲ではそれらの分散粒子が腐食の起点となり、局所的な孔食による貫通孔の発生は抑制され、優れた耐孔食性が得られる。
<Defining the size and number of Si particles>
0.1-1.0 μm Si particles: 3 × 10 2 to 3 × 10 5 particles / mm 2
The part where the Si particles exist on the surface of the sacrificial anode material suppresses the formation of an oxide film, resulting in a film defect, and at the brazing temperature, the matrix near the Si particles has a low melting point due to Si diffusion, and the wettability with the brazing material Is improved, and the bondability of the tube column is improved. Further, since the Si particles generate a defective portion of the oxide film, the surrounding area becomes a starting point of corrosion, and the corrosion form becomes planar. Within the scope of the present invention, these dispersed particles serve as a starting point of corrosion, and the generation of through holes due to local pitting corrosion is suppressed, and excellent pitting corrosion resistance is obtained.
ただし、Ｓｉ粒子のサイズが、円相当径で０．１μｍより小さい場合は、皮膜の欠陥部を生成する作用が得られず、円相当径で１．０μｍより大きい場合はこれら粒子の周辺が腐食されるため孔食サイズが大きくなり、深い孔食が発生する。したがって、円相当径で０．１〜１．０μｍのサイズのＳｉ粒子の分布密度に着目する必要がある。 However, when the size of the Si particles is less than 0.1 μm in the equivalent circle diameter, the effect of generating a defective portion of the film cannot be obtained, and when the equivalent circle diameter is greater than 1.0 μm, the periphery of these particles is corroded. As a result, the pitting size increases and deep pitting occurs. Therefore, it is necessary to pay attention to the distribution density of Si particles having an equivalent circle diameter of 0.1 to 1.0 μm.
上記サイズのＳｉ粒子の数が１ｍｍ２当たりで３×１０２個より少ない場合は、腐食の起点が少ないため腐食形態が面状にならず、深い孔食が発生する。一方、１ｍｍ２当たりのＳｉ粒子の数が３×１０５個より多い場合、腐食速度が増加するため犠牲陽極材の自己腐食性が増加し、犠牲陽極材の作用が早期に失われる。したがって、上記サイズのＳｉ粒子の分布密度を３×１０２〜３×１０５個／ｍｍ２とするのが望ましい。なお、該分布密度は、好ましくは、下限を５×１０２個／ｍｍ２、上限を１×１０５個／ｍｍ２とするのが一層望ましい。 If the number of Si particles of the size is less than 3 × 10 2 cells in 1 mm 2 per, the corrosion form because less starting point of corrosion does not become planar, deep pitting occurs. On the other hand, when the number of Si particles per 1 mm 2 is more than 3 × 10 5 , the corrosion rate increases, so that the self-corrosion property of the sacrificial anode material increases, and the action of the sacrificial anode material is lost early. Therefore, it is desirable that the distribution density of the Si particles of the above size is 3 × 10 2 to 3 × 10 5 particles / mm 2 . The lower limit of the distribution density is preferably 5 × 10 2 pieces / mm 2 and the upper limit is preferably 1 × 10 5 pieces / mm 2 .
すなわち、本発明の強度および耐孔食性に優れるアルミニウム合金クラッド材によれば、アルミニウム合金芯材の片面にアルミニウム合金ろう材がクラッドされ、前記芯材の他方の片面に犠牲陽極材がクラッドされたアルミニウム合金クラッドにおいて、前記犠牲陽極材は、質量％で、Ｚｎ：０．５〜１０．０％、Ｓｉ：０．８〜１．５％、Ｍｇ：０．００５〜０．２％を含み、所望によりＮｉ：０．１〜１．５％を含み、また所望によりＴｉ：０．０５〜０．３％、Ｚｒ：０．０５〜０．３％のうち１種または２種以上を含み、残部がＡｌと不可避不純物からなるとともに、前記不可避不純物中のＦｅと前記Ｓｉ量の割合がＦｅ量（ｗｔ％）≦１／４×Ｓｉ量（ｗｔ％）の関係を満足し、さらに、マトリックス中に円相当径で０．１〜１．０μｍのＳｉ粒子が１ｍｍ２当たり１５０００〜３×１０５個分布しているので、ろう付性および耐孔食性において顕著に優れており、自動車用ラジエーター、ヒーターコアなどのチューブ材、ヘッダープレート材に好適に適用でき、熱交換器の寿命向上に大いに貢献し得る効果がある。 That is, according to the aluminum alloy clad material excellent in strength and pitting corrosion resistance of the present invention, the aluminum alloy brazing material is clad on one side of the aluminum alloy core material, and the sacrificial anode material is clad on the other side of the core material. In the aluminum alloy clad, the sacrificial anode material includes, in mass%, Zn: 0.5 to 10.0%, Si: 0.8 to 1.5%, Mg: 0.005 to 0.2%, If desired, Ni: 0.1 to 1.5%, optionally Ti: 0.05 to 0.3%, Zr: 0.05 to 0.3% of one or two or more, The balance is made of Al and inevitable impurities, and the ratio of Fe to Si in the inevitable impurities satisfies the relationship of Fe amount (wt%) ≦ 1/4 × Si amount (wt%). The equivalent circle diameter is 0.1 to 1. Since μm of Si particles are 1 mm 2 per 15000 to 3 × 10 5 cells distributed in the brazing property and pitting corrosion resistance is remarkably superior, automobile radiators, tubing such as a heater core, a header plate member It can be applied suitably and has the effect of greatly contributing to the improvement of the life of the heat exchanger.
本発明の熱交換器用アルミニウム合金クラッド材は、芯材、犠牲陽極材およびろう材を構成するアルミニウム合金を、通常は、半連続鋳造により造塊し、芯材および犠牲陽極材については均質化処理した後、それぞれ所定厚さまで熱間圧延する。なお、連続鋳造圧延によってそれぞれの板材を得ることも可能である。上記犠牲陽極材としては、前記した組成に調製したアルミニウム合金が用いられる。また、芯材の組成は本発明としては特定のものに限定をされるものではなく、通常は、強度特性に優れたＡｌ−Ｍｎ−Ｃｕ系合金やＡｌ−Ｍｎ−Ｃｕ−Ｓｉ系合金が用いられる。また、ろう材の組成も本発明としては特定のものに限定をされるものではないが、一般にろう材として用いられているＡｌ−Ｓｉ系合金やＡｌ−Ｓｉ−Ｚｎ系合金を用いることができる。 The aluminum alloy clad material for a heat exchanger according to the present invention is typically formed by ingot-making aluminum alloy constituting the core material, the sacrificial anode material and the brazing material by semi-continuous casting, and the core material and the sacrificial anode material are homogenized. Then, each is hot rolled to a predetermined thickness. Each plate material can be obtained by continuous casting and rolling. As the sacrificial anode material, an aluminum alloy prepared in the above-described composition is used. In addition, the composition of the core material is not limited to a specific one in the present invention, and usually an Al-Mn-Cu alloy or Al-Mn-Cu-Si alloy having excellent strength characteristics is used. It is done. Further, the composition of the brazing material is not limited to a specific one in the present invention, but an Al—Si based alloy or an Al—Si—Zn based alloy generally used as a brazing material can be used. .
これらの材料は、その後、芯材、犠牲陽極材およびろう材の各材料を組み合わせ、熱間圧延によりクラッド材とし、最終的に所定厚さまで冷間圧延する工程を経て作製される。
クラッド材の製造工程において犠牲陽極材中に前記Ｓｉ析出物が生成するが、この析出物のサイズや分布は主に製造時の熱処理条件によって決まるため、安定的に析出させるには下記の製造方法が好適である。
These materials are manufactured through a process of combining the core material, the sacrificial anode material, and the brazing material, forming a clad material by hot rolling, and finally cold rolling to a predetermined thickness.
The Si precipitates are formed in the sacrificial anode material in the manufacturing process of the clad material, but the size and distribution of the precipitates are mainly determined by the heat treatment conditions at the time of manufacture. Is preferred.
犠牲陽極材の前記均質化処理は３５０〜５５０℃、さらに好ましくは４００〜５００℃の温度で、２時間以上保持することが望ましい。均質化処理が３５０℃未満では耐食性の向上への寄与が低い０．１μｍ以下のＳｉ粒子の析出が促進され、５００℃を超えると１μｍ以上の粗大な化合物が析出し、同部位を起点に深い孔食が発生しやすくなる。また均質化処理時間が２時間未満では、Ｓｉ粒子の析出が不十分となり、その効果がほとんど得られない。 The homogenization treatment of the sacrificial anode material is desirably held at a temperature of 350 to 550 ° C, more preferably 400 to 500 ° C for 2 hours or more. When the homogenization treatment is less than 350 ° C., precipitation of Si particles of 0.1 μm or less, which has a low contribution to the improvement of corrosion resistance, is promoted, and when it exceeds 500 ° C., coarse compounds of 1 μm or more are precipitated and deep from the same site. Pitting corrosion tends to occur. On the other hand, when the homogenization time is less than 2 hours, the precipitation of Si particles becomes insufficient and the effect is hardly obtained.
また、上記均質化処理後、ろう付熱処理時にもＳｉ析出物の分布状態は変化するが、通常のろう付熱処理（６００℃に０．５〜１５分保持後、１００℃／分以下の冷却速度で冷却）を行なえば、ろう付の冷却時やその後、熱交換器として使用される間にＳｉ析出が起こり、本発明に記載した範囲の分布状態を得ることが出来る。 Moreover, the distribution state of Si precipitates also changes during the brazing heat treatment after the homogenization treatment, but the normal brazing heat treatment (cooling rate of 100 ° C./min or less after holding at 600 ° C. for 0.5 to 15 minutes) in by performing the cooling), cooling time and subsequent brazing, occurs Si precipitated during use as a heat exchanger, can be obtained the distribution of the range described in this invention.
上記で得られたクラッド材１は、図１（ａ）に示すように、芯材２の片面にアルミニウム合金ろう材３がクラッドされ、芯材２の他面に犠牲陽極材４がクラッドされている。このアルミニウム合金クラッド材１は、犠牲陽極材４が管内面となるように曲げ成形されて管状にされる。図１に示す形態では、図１（ｂ）に示すように内面中央部にそれぞれアルミニウム合金クラッド材１の両端側を密着させるようにして、内柱部１ａを形成し、その両側に冷媒経路５、５を確保する。また、管の外面側に位置するアルミニウム合金ろう材３には、図示しないフィンなどを密着させてろう付け加熱を行う。なお、ろう付けにおける加熱条件や雰囲気、フラックスの種別などについては本発明としては特に限定をされるものではない。該ろう付けに際し、犠牲陽極材４は、ろうとの良好な濡れ性を示し、管内面とアルミニウム合金クラッド材１の端部とが、フィレット６、６の形成によって良好に接合される。
The
以下の製造工程により熱交換器用アルミニウム合金クラッド材として発明材および比較材の作製を行なった。芯材（ＪＩＳ３００３合金：Ａｌ−１．０％Ｍｎ−０．１５％Ｃｕ、残部Ａｌおよび不可避不純物）、表１に示す成分を有する犠牲陽極材、およびろう材（ＪＩＳ４３４３合金：Ａｌ−７．５％Ｓｉ、残部Ａｌおよび不可避不純物）をそれぞれ半連続鋳造により造塊し、芯材については６００℃×６ｈｒの条件、犠牲陽極材については表２に示す条件により均質化処理を実施し、それぞれ所定厚さまで熱間圧延した。
その後、犠牲陽極材、芯材、ろう材のクラッド率がそれぞれ１５％、７５％、１０％となるように各材料を組み合わせて熱間圧延により３層材とし、厚さ約６ｍｍ厚まで熱間圧延後、適宜中間焼鈍を行ないながら冷間圧延により板厚０．２０ｍｍ、調質Ｈ１４のクラッド材を作製した。
Invention materials and comparative materials were produced as aluminum alloy clad materials for heat exchangers by the following manufacturing process. Core material (JIS 3003 alloy: Al-1.0% Mn-0.15% Cu, balance Al and inevitable impurities), sacrificial anode material having the components shown in Table 1, and brazing material (JIS 4343 alloy: Al-7.5) % Si, balance Al and unavoidable impurities) are each agglomerated by semi-continuous casting, and homogenized by a condition of 600 ° C. × 6 hr for the core material and the conditions shown in Table 2 for the sacrificial anode material. Hot rolled to thickness.
After that, the sacrificial anode material, the core material, and the brazing material are combined with each other so that the cladding ratios are 15%, 75%, and 10%, respectively, to form a three-layer material by hot rolling, and hot to a thickness of about 6 mm. After rolling, a clad material having a thickness of 0.20 mm and a tempered H14 was prepared by cold rolling while appropriately performing intermediate annealing.
［犠牲陽極材中のＳｉ析出物のサイズおよび個数の測定］
作製したクラッド材を高純度窒素ガス雰囲気中で６００℃に３分間保持するろう付熱処理を行なった後、以下に示す方法により犠牲陽極材中のＳｉ析出物の測定を行なった。
犠牲陽極材表面を圧延目が消えるまで機械研磨した後、電解研磨を実施し、日本電子社製のＥＰＭＡ（ＪＸＡ−８９００ＲＬ）により倍率２０００倍で犠牲陽極材の組成像を撮影し、分散粒子の数および円相当径を測定した。次に粒子解析により測定された分散粒子の成分の特定を行なった。円相当径で０．１〜１．０μｍのサイズのＳｉ析出物の１ｍｍ２当たりの数は２０００倍で２０視野（合計０．０５ｍｍ２）測定を実施し、算出を行なった。その結果を表２に示した。
[Measurement of size and number of Si precipitates in sacrificial anode material]
The prepared clad material was subjected to a brazing heat treatment in which the clad material was held at 600 ° C. for 3 minutes in a high-purity nitrogen gas atmosphere, and then Si precipitates in the sacrificial anode material were measured by the following method.
After mechanically polishing the surface of the sacrificial anode material until the rolling marks disappear, electrolytic polishing was performed, and a composition image of the sacrificial anode material was photographed at a magnification of 2000 using EPMA (JXA-8900RL) manufactured by JEOL Ltd. Numbers and equivalent circle diameters were measured. Next, the components of the dispersed particles measured by particle analysis were identified. The number of Si precipitates with an equivalent circle diameter of 0.1 to 1.0 μm per 1 mm 2 was 2000 times and 20 fields of view (total 0.05 mm 2 ) were measured and calculated. The results are shown in Table 2.
［腐食試験１］
作製したクラッド材を高純度窒素ガス雰囲気中で６００℃に３分間保持するろう付熱処理を行なった後、これを５０ｍｍ長さ×４０ｍｍ幅に切り出して腐食試験用の供試材とした。Ｃｌ−：１９５ｐｐｍ、ＳＯ４ ２−：６０ｐｐｍ、Ｆｅ３＋：３０ｐｐｍ、Ｃｕ２＋：１ｐｐｍを含む酸性の水溶液（ｐＨ３．０）を腐食液とし、試験材を自動車用熱交換器の冷却水を想定して８０℃に８時間保持した後、室温で１６時間保持するという温度サイクルを加えながら、浸漬試験を４週間実施した後、犠牲陽極材側の最大孔食深さを測定し、酸性環境下での耐孔食性を評価した。その結果を表２に示した。
[Corrosion test 1]
The clad material thus prepared was brazed and heat-treated at 600 ° C. for 3 minutes in a high-purity nitrogen gas atmosphere, and then cut into 50 mm length × 40 mm width to provide a test material for corrosion test. An acidic aqueous solution (pH 3.0) containing Cl − : 195 ppm, SO 4 2− : 60 ppm, Fe 3+ : 30 ppm, Cu 2+ : 1 ppm is assumed as a corrosive liquid, and the test material is assumed to be cooling water for an automotive heat exchanger. After the immersion test was conducted for 4 weeks, the maximum pitting corrosion depth on the sacrificial anode material side was measured under an acidic environment. The pitting corrosion resistance of was evaluated. The results are shown in Table 2.
［腐食試験２］
作製したクラッド材を高純度窒素ガス雰囲気中で６００℃に３分間保持するろう付熱処理を行なった後、これを５０ｍｍ長さ×４０ｍｍ幅に切り出して腐食試験用の供試材とした。水道水中に市販のロングライフクーラントを濃度１０ｖｏｌ％となるように添加し、ＮａＯＨにてｐＨ１１に調整したアルカリ溶液を腐食液とし、自動車用熱交換器の冷却水を想定して８０℃に８時間保持した後、室温で１６時間保持するという温度サイクルを加えながら、浸漬試験を４週間実施した後、犠牲陽極皮材側の最大孔食深さを測定し、酸性環境下での耐孔食性を評価した。その結果を表２に示した。
[Corrosion test 2]
The clad material thus prepared was brazed and heat-treated at 600 ° C. for 3 minutes in a high-purity nitrogen gas atmosphere, and then cut into 50 mm length × 40 mm width to provide a test material for corrosion test. Commercially available long-life coolant is added to tap water to a concentration of 10 vol%, and an alkaline solution adjusted to
［ろう付性］
作製したクラッド材を図１に示した断面形状のろう付造管チューブに成形し、このチューブとフィンおよびヘッダープレートを組み合わせてノコロックフラックスを約３ｇ／ｍ２塗布した後、高純度窒素ガス雰囲気中でろう付熱処理を行ない、熱交換器を作製した（チューブ幅：１６ｍｍ、チューブ段数：３２段、コアサイズ：３２０ｍｍｌ×３５０ｍｍｗ）。
その後、作製したラジエータに０．５⇔１５０ｋＰａの繰り返し加圧試験を実施し、チューブに破断が発生するまでの回数を測定した。チューブ内柱部に１ヶ所でも接合不良がある場合、破断までの回数は著しく低下するため、本試験によりろう付性の評価が可能となる。
[Brassability]
The produced clad material is formed into a brazed tube tube having the cross-sectional shape shown in FIG. 1, and this tube is combined with a fin and a header plate, and a noclock flux is applied at about 3 g / m 2, and then a high purity nitrogen gas atmosphere Brazing heat treatment was performed therein to produce a heat exchanger (tube width: 16 mm, number of tube stages: 32 stages, core size: 320 mm × 350 mmw).
Thereafter, a repeated pressurization test of 0.5 to 150 kPa was performed on the manufactured radiator, and the number of times until the tube was broken was measured. In the case where there is a joint failure even at one place in the tube column, the number of times until breakage is remarkably reduced, so that the brazing property can be evaluated by this test.
表２から明らかなように、本発明材では、酸性からアルカリ環境までの広いｐＨ領域で優れた耐食性を示し、ろう付性においても優れた特性を示した。 As is apparent from Table 2, the material of the present invention exhibited excellent corrosion resistance in a wide pH range from acidic to alkaline environments, and also exhibited excellent characteristics in brazing.
１ アルミニウム合金クラッド材
２ 芯材
３ アルミニウム合金ろう材
４ 犠牲陽極材
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