【発明の詳細な説明】[Detailed description of the invention]
（産業上の利用分野）
本発明は主として電力トランス、高周波トラン
スなどの電力変換器の鉄心として用いられる非晶
質合金薄帯の表面処理方法に関するものである。
（従来の技術）
変圧器や回転機など、電磁機器に使用される鉄
心材料は、電磁気特性として、励磁特性が良好
で、鉄損が低いことが要求される。鉄損を低くす
るには、欠陥を少くし、内部応力を下げてヒステ
リシス損を下げ、更に電気抵抗を高くし、板厚を
薄くして渦電流損を低減させねばならない。この
様な条件を満す材料として、珪素鋼板が、通常用
いられてきている。
ところが近年、合金を高温の溶融条件より超急
冷し、液体と同じ構造をもつ非晶質合金の薄帯を
大量につくる方法が開発されてきた。一方非晶質
合金は異方性がなく、電気抵抗も高く、鉄損が著
しく低く、励磁特性も良好で鉄心材料として大い
に期待され、種々の組成の非晶質合金が発表され
ている。
非晶質合金薄帯が、トランス鉄心等に加工され
て使用される場合、鉄心としての特性が問題とな
る。すなわち、層間抵抗、耐食性等である。層間
抵抗が小さいと層間を流れる渦電流が大きくな
り、鉄損を増加させることになる。このためけい
素鋼などでは材料の表面に絶縁を目的とする皮薄
を施している。非晶質材料の場合、それ自身の比
抵抗がけい素鋼など結晶材料の数倍大きいため
に、誘導される渦電流は本来小さくなること、さ
らに板厚が薄く、かつ板の表面には適当な凹凸が
あるため、板同志は面接触とはならず、もともと
層間抵抗が大きいことを理由に、絶縁皮膜を付与
して層間抵抗を高める必要性はないとされてい
た。むしろコーテイングすることによつて、板厚
が薄く、表面が粗いために低い占積率をさらに大
幅に低下させることになり、かえつて磁気特性を
劣化させることが指摘されていた。
しかしアモルフアス合金自体の磁気特性を損な
わずに絶縁皮膜を付与できれば、渦電流による鉄
損の低下をたしかにおさえることができるわけ
で、特に大型の巻鉄心にアモルフアス薄板材料を
使用する場合には、何らかの絶縁皮膜が必要と考
えられるようになつて来た。
一方アモルフアス合金は磁性用材料として用い
られるものには通常クロムが含まれておらず耐食
性に問題があつた。
このため、近年表面に絶縁被膜処理を施し、例
えば特開昭58−74025号公報に示される様に誘導
機の渦流損を低下させる試みが発表されている。
非晶質合金材料が実際に使用される環境での耐
食性、更には大容量機器に使用される場合の絶縁
の問題から、表面処理は不可欠と考えられるが、
従来のコーテイングでは皮膜の特性から焼鈍後に
歪を残して鉄損を悪くしたり皮膜の厚みを均一に
出来ず、焼鈍後不均一応力を生じ鉄損を悪くして
いる問題があつた。また表面粗さが大きい為、表
面凸部の層間抵抗の低下が避けられない問題があ
つた。
（発明が解決しようとする問題点）
本発明は、非晶質磁性薄帯の良好な磁気特性を
保持しつつ、高い層間絶縁抵抗をもつ皮膜を得る
ことを目的としたものである。
（問題点を解決するための手段）
本発明は、溶液の陽極処理を行い酸化物系皮膜
を非晶質磁性薄帯に均一に塗布することにより表
面粗さが大きな薄帯でも層間抵抗を高く出来、且
つ焼鈍後、薄帯表面に不均一歪を残さず良好な磁
気特性を確保することを特徴とする。
すなわち、非晶質合金薄帯の表面に、絶縁皮膜
を生成するに際し、非晶質合金薄帯を陽極とし、
電解溶液中につけて、陰極との間に電圧をかけ、
陽極である非晶質合金薄帯表面に溶液からの酸化
物を均一に付着せしめ、高層間抵抗と良好な磁気
特性を同時に満足させる表面皮膜を得る。
以下本発明を詳細に説明する。
非晶質合金薄帯の磁気特性は、磁気異方性が小
さいこと、固有抵抗が大きいこと、板厚が薄いこ
とにより鉄損が非常に小さくなるとされている。
また磁歪の大きな非晶質合金、例えば、Fe−Si
−Ｂ系非晶質合金においては、応力に対して、磁
気特性変化が非常に大きく、特に非晶質合金薄帯
に圧縮応力が誘起されれば、極端に磁気特性は低
下する。また、不均一応力がある場合も同様であ
る。特に商用周波数域（50〜60Hz）での磁気特性
の劣化が大きく、電力トランス用鉄心に使われる
場合に問題となる。
一方非晶質合金薄帯は特に単ロール法で鋳造さ
れる場合、ロール側表面にエアポケツトと呼ばれ
る凹みを多数発生し、ロール面側と反対の面まで
影響を及ぼし、表面粗さを大きくする。この様な
非晶質薄帯に、通常行われている塗布法、即ち浸
漬法、バーコート法、ロールコート法、スプレー
コート法等を使用すれば非晶質合金薄帯表面の凹
部にコーテイング液が溜り皮膜が厚くなり、他方
凸部はコーテイング液付着量が少なく、皮膜は薄
くなる。この様な皮膜の不均一厚みは非晶質合金
薄帯に不均一応力を誘起し焼鈍後の磁気特性を悪
くする。層間絶縁抵抗を確保する場合、層間抵抗
は非晶質合金薄帯表面の凸部で決まるため、この
部分に、所定以上の皮膜厚を付着させるには、凹
部のコーテイング液量は非常に多くなり皮膜厚は
極端に厚くなり、薄帯に生じる不均一応力も大き
くなり、磁気特性の劣化も大きくなる。
一方皮膜組成は、結晶化温度以下の温度で焼鈍
に耐える必要があるため、無機系、酸化物系の皮
膜が望ましく、熱膨張係数の小さい皮膜が良い。
本発明では、この様に耐熱性があり層間絶縁特
性が良く、熱膨張係数の小さな酸化物系皮膜を、
非晶質合金薄帯を水溶液中で陽極処理を行うこと
により、表面粗さが大きな非晶質合金薄帯の凸、
凹部共に均一に皮膜が塗布出来、磁気特性の良好
な皮膜付非晶質合金薄帯を提供出来る。
本発明で皮膜とする酸化物は通常の溶液電解法
で陽極上に付着する酸化物すべてが使用出来る
が、Al2O3、ZrO2、TaO2等が実際的である。
塗布方法は、非晶質合金薄帯の両面、片面いず
れも処理可能である。特に、単ロール法で鋳造さ
れた非晶質合金薄帯ではロール面のみ処理を行つ
た場合に同一付着量でも自由面のみ処理にくらべ
鉄損を向上させることが可能である。連続的に処
理を行う場合、片面塗布はロール面上で連続処理
を簡単に行える利点がある。層間絶縁抵抗は、薄
帯の凸部の皮膜厚さで決るため積層した場合に
は、片面塗布でも十分確保出来る。
非晶質合金薄帯は前述の如く磁気特性が不均一
応力によつて容易に劣化する。酸化物系皮膜もそ
の膜厚が厚過ぎれば、表面粗さが大きい場合、均
一に付着していても不均一応力を生じ磁気特性、
特に商用周波数鉄損を悪くする傾向が出てくる。
この不均一応力は非晶質合金薄帯の板厚が薄いと
同一皮膜厚でも、板厚の厚い場合にくらべて大き
くなる。
従つて皮膜厚は第１図に示す様に非晶質単位板
厚μｍ当り10mg／m2以下、望ましくは５mg／m2以
下が商用周波数鉄損を損わず良好な皮膜特性を得
ることが出来る。
なお、第１図は商用周波数での塗布量に対する
鉄損の劣化率を示したものである。また、高周波
鉄損を問題とする場合では、商用周波数の場合に
比べ渦流損の比率が大きくするため、鉄損劣化が
小さくなり、従つて、10mg／m2以上の付着量でも
使用可能である。
（実施例）
実施例 １
単ロール法で作製された組成Fe79.5B13.1Si6.9
C0.5（原子％）、板厚25μｍの非晶質合金薄帯をア
ルミン酸ソーダを含む電解液中で陽極処理を行
い、Al2O3を該薄帯表面に3A／ｄm2の電流で、処
理時間を変え塗布した。単位厚当りの皮膜厚が
3.6mg／m2・μｍ(A)、12.3mg／m2・μｍ(B)、18
mg／m2・μｍ(C)の３種類の非晶質合金薄帯を得、
試料とした。乾燥後、磁場中焼鈍をN2中雰囲気
で行い、1.3T、50Hzでの鉄損（W13/50）、層間抵
抗（JIS2法）を測定した。表１にその結果を示
す。
(Industrial Application Field) The present invention mainly relates to a method for surface treatment of an amorphous alloy ribbon used as an iron core of a power converter such as a power transformer or a high frequency transformer. (Prior Art) Iron core materials used in electromagnetic equipment such as transformers and rotating machines are required to have good excitation characteristics and low iron loss. In order to lower iron loss, it is necessary to reduce defects, lower internal stress to lower hysteresis loss, increase electrical resistance, and reduce plate thickness to reduce eddy current loss. Silicon steel plates have been commonly used as a material that satisfies these conditions. However, in recent years, a method has been developed to ultra-quench alloys from high-temperature melting conditions to produce large quantities of amorphous alloy ribbons with the same structure as liquids. On the other hand, amorphous alloys have no anisotropy, have high electrical resistance, extremely low iron loss, and good excitation characteristics, and are highly expected as iron core materials, and amorphous alloys with various compositions have been published. When an amorphous alloy ribbon is processed into a transformer core or the like, its properties as a core become a problem. That is, interlayer resistance, corrosion resistance, etc. When the interlayer resistance is small, the eddy current flowing between the layers becomes large, leading to an increase in iron loss. For this reason, a thin layer is applied to the surface of materials such as silicon steel for the purpose of insulation. In the case of amorphous materials, the resistivity of the material itself is several times higher than that of crystalline materials such as silicon steel, so the induced eddy current is inherently smaller. Because of the unevenness, the plates do not come into surface contact with each other, and because the interlayer resistance is originally high, it was thought that there was no need to add an insulating film to increase the interlayer resistance. On the contrary, it has been pointed out that by coating, the space factor, which is low due to the thin plate thickness and rough surface, is further significantly reduced, and on the contrary, the magnetic properties are deteriorated. However, if an insulating film can be applied without impairing the magnetic properties of the amorphous alloy itself, it will certainly be possible to suppress the drop in iron loss caused by eddy currents. Especially when using amorphous thin plate material for a large wound core, it is possible to Insulating coatings have come to be considered necessary. On the other hand, amorphous amorphous alloys used as magnetic materials usually do not contain chromium and have a problem in corrosion resistance. Therefore, in recent years, attempts have been made to reduce the eddy current loss of induction machines by applying an insulating coating to the surface, as shown in, for example, Japanese Patent Application Laid-open No. 74025/1983. Surface treatment is considered essential due to corrosion resistance in the environment where amorphous alloy materials are actually used, as well as insulation issues when used in large-capacity equipment.
Due to the characteristics of the coating, conventional coatings have problems such as leaving distortions after annealing, which worsens iron loss, and the coating thickness cannot be made uniform, resulting in uneven stress after annealing, which worsens iron loss. Furthermore, since the surface roughness is large, a problem arises in which a decrease in interlayer resistance at the surface convex portions is unavoidable. (Problems to be Solved by the Invention) The object of the present invention is to obtain a film having high interlayer insulation resistance while maintaining the good magnetic properties of an amorphous magnetic ribbon. (Means for Solving the Problems) The present invention achieves high interlayer resistance even in a thin strip with large surface roughness by uniformly applying an oxide film to an amorphous magnetic thin strip by anodizing a solution. It is characterized by ensuring good magnetic properties without leaving any non-uniform strain on the surface of the ribbon after being produced and annealed. That is, when forming an insulating film on the surface of an amorphous alloy ribbon, the amorphous alloy ribbon is used as an anode,
Immerse it in an electrolytic solution and apply a voltage between it and the cathode.
Oxide from a solution is uniformly deposited on the surface of an amorphous alloy ribbon serving as an anode to obtain a surface film that satisfies interlayer resistance and good magnetic properties at the same time. The present invention will be explained in detail below. The magnetic properties of amorphous alloy ribbons are said to be such that iron loss is extremely small due to their small magnetic anisotropy, large specific resistance, and thin plate thickness.
Also, amorphous alloys with large magnetostriction, such as Fe-Si
-B-based amorphous alloys have very large changes in magnetic properties in response to stress, and in particular, if compressive stress is induced in the amorphous alloy ribbon, the magnetic properties will be extremely degraded. The same applies when there is non-uniform stress. The deterioration of magnetic properties is particularly large in the commercial frequency range (50 to 60Hz), which is a problem when used in power transformer cores. On the other hand, especially when an amorphous alloy ribbon is cast by a single roll method, many dents called air pockets are generated on the roll side surface, which affects the surface opposite to the roll side and increases the surface roughness. If a commonly used coating method such as a dipping method, bar coating method, roll coating method, or spray coating method is used on such an amorphous alloy ribbon, the coating liquid will be applied to the recesses on the surface of the amorphous alloy ribbon. On the other hand, the amount of coating liquid deposited on the convex portions is small, resulting in a thin film. Such non-uniform thickness of the film induces non-uniform stress in the amorphous alloy ribbon and deteriorates the magnetic properties after annealing. When ensuring interlayer insulation resistance, the interlayer resistance is determined by the convexities on the surface of the amorphous alloy ribbon, so in order to deposit a film with a thickness greater than the specified value on these areas, the amount of coating liquid in the concave areas must be extremely large. The film thickness becomes extremely thick, the non-uniform stress generated in the ribbon becomes large, and the deterioration of magnetic properties becomes large. On the other hand, as for the coating composition, since it is necessary to withstand annealing at a temperature below the crystallization temperature, an inorganic or oxide coating is desirable, and a coating with a small coefficient of thermal expansion is preferable. In the present invention, we use an oxide film that is heat resistant, has good interlayer insulation properties, and has a small coefficient of thermal expansion.
By anodizing the amorphous alloy ribbon in an aqueous solution, the amorphous alloy ribbon has a large surface roughness.
The coating can be uniformly applied to both the recesses, and a coated amorphous alloy ribbon with good magnetic properties can be provided. As the oxide to form the film in the present invention, any oxide that adheres to the anode by a normal solution electrolysis method can be used, but Al 2 O 3 , ZrO 2 , TaO 2 and the like are practical. The coating method can treat either both sides or one side of the amorphous alloy ribbon. In particular, in the case of an amorphous alloy ribbon cast by a single roll method, when only the roll surface is treated, it is possible to improve iron loss compared to when only the free surface is treated, even with the same amount of coating. When performing continuous processing, single-sided coating has the advantage that continuous processing can be easily performed on the roll surface. Since the interlayer insulation resistance is determined by the film thickness of the convex portion of the ribbon, when laminated, it can be sufficiently ensured by single-sided coating. As mentioned above, the magnetic properties of an amorphous alloy ribbon easily deteriorate due to non-uniform stress. If the oxide film is too thick or has a large surface roughness, it will cause uneven stress even if it is evenly deposited, which will affect the magnetic properties.
In particular, there is a tendency to worsen commercial frequency iron loss.
This non-uniform stress becomes larger when the amorphous alloy ribbon is thinner than when the amorphous alloy ribbon is thicker, even if the coating thickness is the same. Therefore, as shown in Figure 1, the film thickness should be 10 mg/m 2 or less, preferably 5 mg/m 2 or less per μm of amorphous plate thickness, in order to obtain good film characteristics without impairing commercial frequency iron loss. I can do it. Note that FIG. 1 shows the deterioration rate of iron loss with respect to the coating amount at commercial frequencies. In addition, when high frequency iron loss is an issue, the ratio of eddy current loss is larger than in the case of commercial frequencies, so iron loss deterioration is reduced, and therefore it can be used even with a coating weight of 10mg/ m2 or more. . (Example) Example 1 Composition produced by single roll method Fe 79.5 B 13.1 Si 6.9
An amorphous alloy ribbon containing C 0.5 (at. The treatment time was changed and the coating was applied. Film thickness per unit thickness
3.6mg/m 2・μm (A), 12.3mg/m 2・μm (B), 18
Three types of amorphous alloy ribbons of mg/m 2 μm (C) were obtained.
It was used as a sample. After drying, magnetic field annealing was performed in a N 2 atmosphere, and core loss (W 13/50 ) and interlayer resistance (JIS2 method) at 1.3 T and 50 Hz were measured. Table 1 shows the results.
【表】
本発明によるＡ、Ｂは層間抵抗、鉄損共に優
れ、鉄心用材料用の皮膜として好適であることが
わかつた。
実施例 ２
単ロール法で作製された組成Fe79.5B13.1Si7.1
C0.3（原子％）、板厚40μｍの非晶質合金薄帯を、
アルミン酸ソーダ電解液中で、該薄帯を陽極とし
て100mmφのロールに沿わし薄帯のロール面のみ
を処理し厚み当り５mg／m2・μｍの皮膜を塗布し
た。次に同じ処理を自由面のみに行い試料とし
た。乾燥後磁場中焼鈍をN2中雰囲気で行い、鉄
損（W13/50）層間抵抗（JIS2法）を測定した。表
２に測定結果を示す。[Table] It was found that A and B according to the present invention were excellent in both interlayer resistance and core loss, and were suitable as a coating for iron core materials. Example 2 Composition Fe 79.5 B 13.1 Si 7.1 produced by single roll method
C 0.3 (atomic%), amorphous alloy ribbon with a plate thickness of 40 μm,
In a sodium aluminate electrolyte, the thin strip was passed along a roll of 100 mm diameter using it as an anode, and only the roll surface of the thin strip was treated to coat a film with a thickness of 5 mg/m 2 .mu.m. Next, the same treatment was applied only to the free surface to prepare a sample. After drying, magnetic field annealing was performed in an N 2 atmosphere, and iron loss (W 13/50 ) and interlayer resistance (JIS2 method) were measured. Table 2 shows the measurement results.
【表】
片面処理を行つても、鉄損は良好で且層間抵抗
をも高く出来ることがわかつた。単ロール法によ
る非晶質合金薄帯ではロール面側の処理が鉄損が
良好であることがわかつた。
（発明の効果）
以上説明したように本発明によれば非晶質磁性
薄帯に層間抵抗が高く、且鉄損が良好な均一皮膜
を付着出来、鉄心特性を改善出来、その効果は大
きい。[Table] It was found that even with single-sided treatment, iron loss was good and interlayer resistance could be increased. It was found that for amorphous alloy ribbon produced by the single roll method, treatment on the roll surface side had good iron loss. (Effects of the Invention) As explained above, according to the present invention, a uniform film with high interlayer resistance and good iron loss can be deposited on an amorphous magnetic ribbon, and the core characteristics can be improved, which is highly effective.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は本発明（商用周波数の場合）による皮
膜の単位板厚当りの膜厚と鉄損劣化状況を示す図
である。
FIG. 1 is a diagram showing the film thickness per unit plate thickness of the film according to the present invention (in the case of commercial frequency) and the state of iron loss deterioration.