【発明の詳細な説明】[Detailed description of the invention]
本発明は自動車ラジエーター及びヒーターのフ
イン用銅合金に関するもので、特にラジエーター
の放熱特性を低下せしめることなく、フインの耐
食性を改善したものである。
自動車のラジエーターは、エンジン部の温度上
昇を防止するためのもので、エンジン部とラジエ
ーター間に冷却媒体である水を循環させ、エンジ
ン部で温度上昇した水をラジエーターで放熱させ
ることにより、エンジン部の冷却を行なつてい
る。一般にラジエーターは水の通るチユーブと、
該チユーブより熱を大気中に放散させるフインと
からなり、通常自動車の前部に取り付け、これに
空気を強制的に吹き付けて放熱を促進させてい
る。
従来このようなラジエーターのフインには、
CuにCd又はSnを0.1〜1.0wt％（以下wt％を単に
％と略記）含有せしめた厚さ0.03〜0.2mmの銅合
金薄板が用いられていたが、最近、空気中に塩
素、窒素酸化物、亜硫酸ガス等が増加し、道路に
は凍結防止剤として塩素化合物が散布されるな
ど、自動車の走行環境が著しく悪化し、自動車は
勿論自動車に装着したラジエーターの腐食は加速
の一途をたどつている。
即ち、ラジエーターは放熱性を向上するため、
通常自動車の前部に取り付けられているため、前
記汚染空気が吹きつけられており、更に道路から
は凍結防止剤が跳上がりなどにより汚染空気に混
入し、これがラジエーターのフインし直接接触す
ることになる。従つてラジエーターのフインは前
記腐食性物質と接触する厳しい腐食条件下におか
れておりフインが腐食するとラジエーターの放熱
性が劣化し、更に腐食が進むと、チユーブからフ
インが脱落し、ラジエーターは使用できなくな
る。
近年、自動車は省エネルギー、排ガス等の対策
から軽量化が要求され、自動車の一部であるラジ
エーターにおいても例外でなく、その構成部材で
あるフインにおいても薄肉軽量化が求められてい
る。従つて、フインには単位面積当りの放熱性の
向上と、その寿命維持が重要な課題となつてい
る。
このような状況において、現用のフイン材料で
あるCuにCd又はSnを添加した前記銅合金では腐
食に対する抵抗がほとんどなく、耐食性の改善が
強く望まれている。
本発明はこれに鑑み、フインの腐食状態を詳細
に観察した結果、腐食はフインの金属表面に酸化
物Cu2Ｏが多層に重なり、Cu2Ｏと金属との界面
に塩素及び硫黄が凝集し、更に腐食面は一般に乾
燥状態で水分が微量であることを知見し、このよ
うな条件下における耐食材料について研究を重ね
た結果、熱伝導性及び耐食性が優れ、かつ加工性
が良好な自動車ラジエーターのフイン用銅合金を
開発したもので、Y0.005〜1.0％とIn，Ni，Co，
Crのうち１種又は２種以上の合計0.005〜0.3％と
を含み、残部Cuからなることを特徴とするもの
である。
即ち、本発明は、Cuに少量のＹを添加するこ
とによりCu特有の熱伝導性をあまり低下せしめ
ることなく、塩素、窒素酸化物、亜硫酸ガス等の
混在する空気中における亜酸化銅の生成及び増殖
を抑制して耐食性を向上せしめ更にこれにIn，
Ni，Co，Crを１種又は２種以上少量添加するこ
とによりＹとの相剰効果によりさらに耐食性を向
上せしめることが可能になる。
しかして本発明の合金組成を前記の如く限定し
たのは次の理由によるものである。
Ｙ含有量を0.005〜1.0％と限定したのは、Ｙ含
有量が0.005％未満ではCu2Ｏの生成、増殖を抑制
する作用が充分でなく、1.0％を超えると耐食性
は向上するも、圧延加工性が悪くなり製造コスト
が大巾に高くなる。またIn，Ni，Co，Crの添加
量を１種又は２種以上の合計で0.005〜0.3％と限
定したのは0.005％未満ではＹとの相剰効果によ
る耐食性の向上が不充分であり0.5％を越えると
Ｙとの相剰効果による耐食性の向上が飽和してし
まい、熱伝導率を低下させるためである。
また本発明合金は残部Cuが、酸素含有量の少
ない無酸化溶解で製造したもの及び大気溶解で製
造した酸素含有量の多いものの両方に適用できる
ものである。
以下本発明を実施例について詳細に説明する。
黒鉛ルツボを用いて、タフピツチ銅を真空中で及
び大気中で溶解し、これに各添加元素を挿入し、
これを金型に鋳造して第１表に示す組成の厚さ25
mm、巾250mm、長さ250mmの鋳塊を得た。
この鋳塊の各表面を一面あたり2.5mm面削した
後、加熱して850℃の温度で熱間圧延し、その後
冷間圧延と中間焼鈍を繰返して厚さ0.5mmの板に
仕上げた。
この板について耐食性、熱伝導性及び圧延加工
性を調べた。その結果を第２表に示す。
耐食性は上記板より縦100mm、横100mmのサンプ
ルを切り出し、0.3％SO2ガスと0.3％Cl2ガスを含
む空気中に48時間暴露し、続いて温度60℃、湿度
80％の恒温恒湿槽内に96時間保持することを４回
繰返し、サンプル表面の腐食生成物であるCu2Ｏ
を除去して重量を測定し、試験前後の重量より腐
食減量を算出した。
また熱伝導性については、これを強い正相関の
関係にある導電率を測定した。
また圧延加工性については、上記板に圧延と焼
鈍をくりかえして厚さ0.1mmの板に仕上げ、これ
を100mの長さに切断して0.02mmの厚さまで圧延
し、該圧延中に発生した圧延切れの回数を求め
た。
The present invention relates to a copper alloy for the fins of automobile radiators and heaters, and in particular improves the corrosion resistance of the fins without deteriorating the heat dissipation characteristics of the radiator. A car radiator is used to prevent the temperature of the engine from rising.By circulating water, which is a cooling medium, between the engine and the radiator, and dissipating the water that has risen in temperature in the engine, the radiator cools the engine. is being cooled. Generally, a radiator has a tube through which water flows,
It consists of a fin that dissipates heat from the tube into the atmosphere, and is usually attached to the front of an automobile, and air is forcedly blown onto it to promote heat dissipation. Conventionally, the fins of such a radiator have
Copper alloy thin sheets with a thickness of 0.03 to 0.2 mm, which contain 0.1 to 1.0 wt% of Cd or Sn to Cu (hereinafter wt% is simply abbreviated as %), have been used, but recently, chlorine and nitrogen oxidation in the air have been used. The driving environment for automobiles has deteriorated significantly, with the increase in the amount of carbon dioxide, sulfur dioxide, etc., and the spraying of chlorine compounds on roads as antifreeze agents, and the corrosion of not only automobiles but also the radiators installed in automobiles is accelerating. It's on. In other words, since radiators improve heat dissipation,
Since it is usually installed at the front of a car, the contaminated air is blown onto it, and the anti-freeze agent jumps up from the road and mixes with the contaminated air, which then comes into direct contact with the radiator fins. Become. Therefore, the fins of the radiator are exposed to severe corrosive conditions as they come into contact with the corrosive substances, and when the fins corrode, the heat dissipation performance of the radiator deteriorates, and if the corrosion progresses further, the fins fall off from the tube and the radiator is no longer usable. become unable. In recent years, automobiles have been required to be lighter in order to save energy and reduce exhaust gas, and radiators, which are a part of automobiles, are no exception, and fins, which are their constituent members, are also required to be thinner and lighter. Therefore, improving the heat dissipation per unit area and maintaining the service life of the fins are important issues. Under these circumstances, the copper alloys that are currently used as fin materials, which are made by adding Cd or Sn to Cu, have almost no resistance to corrosion, and there is a strong desire to improve the corrosion resistance. In view of this, the present invention has carefully observed the state of corrosion of fins and found that corrosion is caused by the formation of multiple layers of oxide Cu 2 O on the metal surface of fins, and the aggregation of chlorine and sulfur at the interface between Cu 2 O and the metal. Furthermore, we discovered that corroded surfaces generally have a trace amount of moisture in dry conditions, and as a result of repeated research on corrosion-resistant materials under such conditions, we have developed an automobile radiator that has excellent thermal conductivity, corrosion resistance, and easy workability. This is a copper alloy developed for fins containing Y0.005~1.0% and In, Ni, Co,
It is characterized by containing one or more types of Cr in a total of 0.005 to 0.3%, with the remainder being Cu. That is, the present invention improves the production of cuprous oxide in air containing chlorine, nitrogen oxides, sulfur dioxide, etc., without significantly reducing the thermal conductivity peculiar to Cu by adding a small amount of Y to Cu. It suppresses proliferation and improves corrosion resistance, and furthermore, In,
By adding a small amount of one or more of Ni, Co, and Cr, it is possible to further improve corrosion resistance due to the mutual effect with Y. The reason why the alloy composition of the present invention is limited as described above is as follows. The reason for limiting the Y content to 0.005 to 1.0% is that if the Y content is less than 0.005%, the effect of suppressing the formation and proliferation of Cu 2 O is insufficient, and if it exceeds 1.0%, although corrosion resistance improves, rolling Workability deteriorates and manufacturing costs increase significantly. In addition, the addition amount of In, Ni, Co, and Cr was limited to 0.005 to 0.3% as one type or the total of two or more types because if it is less than 0.005%, the improvement in corrosion resistance due to the mutual effect with Y is insufficient. %, the improvement in corrosion resistance due to the mutual effect with Y will be saturated and the thermal conductivity will decrease. Furthermore, the alloy of the present invention can be applied both to those produced by non-oxidizing melting with a low residual Cu content and those produced by atmospheric melting with a high oxygen content. The present invention will be described in detail below with reference to examples.
Using a graphite crucible, Toughpitch copper is melted in vacuum and in the air, and each additive element is inserted into it.
This is cast into a mold and the thickness of the composition shown in Table 1 is 25
An ingot with a width of 250 mm and a length of 250 mm was obtained. Each surface of this ingot was milled by 2.5 mm per side, heated and hot rolled at a temperature of 850°C, and then cold rolled and intermediate annealing were repeated to form a plate with a thickness of 0.5 mm. This plate was examined for corrosion resistance, thermal conductivity, and rolling workability. The results are shown in Table 2. Corrosion resistance was measured by cutting a sample 100 mm long and 100 mm wide from the above board, exposing it to air containing 0.3% SO 2 gas and 0.3% Cl 2 gas for 48 hours, and then exposing it to air containing 0.3% SO 2 gas and 0.3% Cl 2 gas, and then exposing it to a temperature of 60°C and humidity.
Holding in a constant temperature and humidity chamber at 80% for 96 hours was repeated four times to remove Cu 2 O, a corrosion product on the sample surface.
was removed, the weight was measured, and the corrosion weight loss was calculated from the weight before and after the test. Regarding thermal conductivity, we measured electrical conductivity, which has a strong positive correlation. Regarding rolling workability, the above plate was repeatedly rolled and annealed to produce a plate with a thickness of 0.1 mm, which was then cut into 100 m lengths and rolled to a thickness of 0.02 mm. The number of breaks was calculated.
【表】【table】
【表】
第１表及び第２表から明らかなように本発明合
金は何れも従来合金No.20に比較し、熱伝導性を著
しく低下させることなく、耐食性が改善され、し
かも加工性も良好であることが判る。
これに対して本発明合金の組成範囲よりＹ含有
量の少ない比較合金No.15，In，Ni，Co，Cr含有
量の少ない比較合金No.16ではいずれも耐食性がそ
れほど改善されず、In，Ni，Co，Cr含有量の多
い比較合金No.18，19では耐食性の向上が著しい反
面、フインとして重要な熱伝導性の低下が著しく
なりフイン材には適さないことが判る。またＹ含
有量が多い比較合金No.18では加工性が悪いことが
判る。
このように本発明合金は、加工性が良好で、塩
素及び硫黄の混在する腐食環境において優れた耐
食性を示し、かつ、フインとして充分な熱伝導性
を有しており、自動車熱交換器のフインに使用
し、自動車熱交換器の寿命を増大させると共に、
軽量化を可能にする顕著な効果を奏するものであ
る。[Table] As is clear from Tables 1 and 2, compared to conventional alloy No. 20, all of the alloys of the present invention have improved corrosion resistance without significantly decreasing thermal conductivity, and also have good workability. It turns out that. On the other hand, the corrosion resistance of Comparative Alloy No. 15, which has a lower Y content than the composition range of the present alloy, and Comparative Alloy No. 16, which has a lower In, Ni, Co, and Cr content, was not significantly improved. Comparative alloys No. 18 and 19, which have a high content of Ni, Co, and Cr, showed a remarkable improvement in corrosion resistance, but on the other hand, the thermal conductivity, which is important for fins, significantly decreased, making them unsuitable for fin materials. In addition, it can be seen that comparative alloy No. 18, which has a high Y content, has poor workability. As described above, the alloy of the present invention has good workability, exhibits excellent corrosion resistance in a corrosive environment containing chlorine and sulfur, and has sufficient thermal conductivity as a fin, making it suitable for use as a fin in automobile heat exchangers. used to increase the lifespan of automotive heat exchangers,
This has a remarkable effect of making it possible to reduce the weight.