JP3577598B2 - Method for producing molten metal bath member having coating excellent in molten metal corrosion resistance and peeling resistance - Google Patents
Method for producing molten metal bath member having coating excellent in molten metal corrosion resistance and peeling resistance Download PDFInfo
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- JP3577598B2 JP3577598B2 JP01435792A JP1435792A JP3577598B2 JP 3577598 B2 JP3577598 B2 JP 3577598B2 JP 01435792 A JP01435792 A JP 01435792A JP 1435792 A JP1435792 A JP 1435792A JP 3577598 B2 JP3577598 B2 JP 3577598B2
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- Prior art keywords
- molten metal
- resistance
- corrosion resistance
- film
- metal bath
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Coating With Molten Metal (AREA)
- Coating By Spraying Or Casting (AREA)
Description
【０００１】
【産業上の利用分野】
本発明は、製鉄機械、特に溶融亜鉛めっきライン等において用いられる溶融金属浴用部材の製造方法に関する。
【０００２】
【従来の技術】
溶融亜鉛めっきライン用金属浴中ロール等としては、各種サーメット系材料を溶射したり、酸化物セラミックス系材料を溶射したものが使われてきたが、サーメット系溶射皮膜は溶融金属耐食性に乏しく、セラミックス系溶射皮膜は剥離しやすいという難点があった。
【０００３】
【発明が解決しようとする課題】
本発明は、溶融金属耐食性および耐剥離性に優れた溶融金属浴用部材の製造方法を提供することを目的とする。
【０００４】
【課題を解決するための手段】
前記の課題は、下記要旨の本発明によって解決される。
基材表面に５〜６０％の硼化物とＣｏ、Ｃｒ、Ｍｏ、Ｗの１種又は２種以上を５〜３０％含有し、残部炭化物および不可避不純物よりなるサーメット材料を溶射した上に、酸化物系セラミックスを厚さ５０〜２００μｍに溶射後、クロム酸（Ｈ２ ＣｒＯ４ およびＨ２ Ｃｒ２ Ｏ７ ）を主成分とする水溶液で含浸処理し、次いで焼成することを特徴とする溶融金属耐食性および耐剥離性に優れた皮膜を有する溶融金属浴用部材の製造方法。
【０００５】
本発明者らはさきにタングステン硼化物等の硼化物を含有する皮膜は溶融金属耐食性に極めて優れていることを確認した。又ＷＢ等はＷＣより若干熱膨脹係数が高いようで溶射皮膜は熱衝撃性にも強いことが考えられる。又、硼化物は酸化性雰囲気ではＢ２ Ｏ３ を表面に生成し、一部表面に残存することが認められた。さらにこの生成Ｂ２ Ｏ３ は低温でガラス化し、溶融温度も低いため、セラミックスが溶射された場合、ソルダー化し、セラミックスとのなじみがよくなると考えられる。本発明者らは、ＷＢ等硼化物を含有したサーメット皮膜の上に酸化物系セラミックス溶射を行った皮膜は溶融金属耐食性に優れるばかりでなく、基材との密着性が高く、剥離し難いことを確認した。
【０００６】
このためボンドコート材料へのＷＢ等硼化物の添加は必須であるが、含有量が少ない場合には、密着強度改善効果がなく、多すぎる時は大気中での良好な溶射は難しくなる。よって硼化物添加量は５〜６０％に限定する。
サーメットとしての金属相としてはＣｏ、Ｃｒ、Ｍｏ、Ｗが選定されるが、ボンドコートサーメットの金属成分としては、これら元素の１種又は２種以上を５〜３０％添加する。金属成分は、少なすぎると皮膜粒子の結合力を弱めるため、最低５％は添加する。又、必要以上に添加すると、皮膜の溶融金属による侵食性が増すため、添加量は３０％までとする。
【０００７】
なお、残部はＷＣ等の炭化物であるが、これら炭化物は硼化物の作用効果を補完し、ボンドコート自体に溶融金属耐食性を与えるものである。
トップコートセラミックスとしては、基材である金属部と熱膨脹率の差が大きくないセラミックスが良好であり、出来るだけ線膨脹係数の大きい材料を選択するのがよい。本発明の実施例では膨脹係数の大きいクロミアを適用している。
【０００８】
トップコート皮膜厚みについては、皮膜厚が過大になると残留応力が増し、セラミックス皮膜内部やボンドコートとトップコートセラミックス界面で剥離しやすくなるので、５０〜２００μｍに限定する（実施例参照）。
又、ボンドコート表面に生成しているＢ２ Ｏ３ は、セラミックス界面でガラス化し、強い密着力を呈するようになる。すなわち本発明はボンドコートの硼化物系サーメットにより硼酸を含むガラス質をつくり、強い密着力をトップコートに与えるものである。
【０００９】
さらに、本発明において、トップコートとして酸化物系セラミックスを溶射後にクロム酸を主成分とする水溶液で含浸処理を行い、焼成処理を行うのは、セラミックス皮膜を緻密化し、皮膜粒子の脱落を抑制するためである。主成分であるＨ２ ＣｒＯ４ 、Ｈ２ Ｃｒ２ Ｏ７ 等は含浸後の加熱で脱水反応を起し、ＣｒＯ３ 化する。ＣｒＯ３ は２００℃程度から溶融し、皮膜を酸化しながらＣｒ２ Ｏ３ 化し、封孔が行われる。この場合ＣｒＯ３ の酸化でＣｒ２ Ｏ３ は皮膜に密着し、皮膜強度を上げることになる。又、モリブデン酸アンモニウムを添加した液ではｐＨ調整と、酸化モリブデンによる封孔を行わせ、封孔効果を補完することができる。
【００１０】
【実施例】
本発明の実施例および比較例を表１（トップコートおよびボンドコート成分）および表２（トップコート溶射後にクロム酸を主成分とする水溶液で含浸焼成処理した後の侵食熱衝撃試験結果）に示す。
Ｎｏ．１〜Ｎｏ．８は本発明の実施例、Ｎｏ．９〜１２は比較例である。Ｎｏ．１〜Ｎｏ．８の実施例においては、ボンドコートとして硼化物を含むサーメットを溶射して皮膜を形成した。トップコートとしてＣｒ２ Ｏ３ を５０μｍ、１００μｍおよび２００μｍ溶射した皮膜は、侵食熱衝撃試験で全く剥離していない。２５０μｍ厚トップコートを溶射した場合に、はじめて皮膜中残留応力のため一部部分剥離を生じた。
【００１１】
これに対して、ボンドコートがＷＣ系である比較例Ｎｏ．９およびＮｉ−Ａｌ系である比較例Ｎｏ．１０の皮膜の場合は、膜厚２００μｍ以下ですでに部分剥離が認められた。又、ボンドコートなしで、セラミックスを溶射した比較例Ｎｏ．１１および１２の皮膜の場合には、膜厚に関係なくすべて剥離した。
これより本発明の部材は溶融金属浴に対する耐食性および耐剥離性の点で優れたものであることが分る。
【００１２】
なお、本実施例ではトップコート材料としてクロミアのみを使用した結果であるが、他の実施例ではアルミナ、ジルコニア・イットリア、スピネル等で同様の結果が得られており、本発明の効果が確認されている。
【００１３】
【表１】
【表２】
【発明の効果】
本発明によれば、溶融金属耐食性および耐剥離性の優れた溶融金属浴用部材を提供することができる。[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a member for a molten metal bath used in an iron making machine, particularly a hot dip galvanizing line or the like.
[0002]
[Prior art]
As a roll in a metal bath for a hot-dip galvanizing line, various cermet-based materials have been sprayed or oxide ceramics-based materials have been sprayed, but the cermet-based sprayed coating has poor molten metal corrosion resistance and ceramics. The system spray coating has a disadvantage that it is easily peeled.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a molten metal bath member excellent in molten metal corrosion resistance and exfoliation resistance.
[0004]
[Means for Solving the Problems]
The above problems are solved by the present invention having the following gist.
A cermet material containing 5 to 60% of boride and one or more of Co, Cr, Mo, and W on the surface of the base material and containing 5 to 30%, and a balance of carbide and unavoidable impurities is sprayed, and then oxidized. Molten ceramics, characterized in that after spraying a material-based ceramic to a thickness of 50 to 200 μm, impregnating with an aqueous solution containing chromic acid (H 2 CrO 4 and H 2 Cr 2 O 7 ) as a main component, and then firing. And a method for producing a member for a molten metal bath having a film having excellent peel resistance.
[0005]
The present inventors have previously confirmed that a film containing a boride such as a tungsten boride is extremely excellent in molten metal corrosion resistance. Also, WB and the like seem to have a slightly higher thermal expansion coefficient than WC, and it is considered that the thermal spray coating has a strong thermal shock resistance. Also, it was recognized that boride forms B 2 O 3 on the surface in an oxidizing atmosphere and partially remains on the surface. Further, since the generated B 2 O 3 is vitrified at a low temperature and has a low melting temperature, it is considered that when the ceramic is sprayed, it becomes a solder and becomes more compatible with the ceramic. The present inventors have found that a coating obtained by spraying an oxide-based ceramic on a cermet coating containing a boride such as WB has not only excellent molten metal corrosion resistance but also high adhesion to a base material and is difficult to peel off. It was confirmed.
[0006]
For this reason, it is essential to add a boride such as WB to the bond coat material. However, when the content is small, there is no effect of improving the adhesion strength, and when the content is too large, it becomes difficult to perform good thermal spraying in the atmosphere. Therefore, the amount of boride added is limited to 5 to 60%.
Co, Cr, Mo, and W are selected as the metal phase as the cermet. One or more of these elements are added as the metal component of the bond coat cermet in an amount of 5 to 30%. If the amount of the metal component is too small, the bonding force of the coating particles is weakened, so at least 5% is added. Also, if added more than necessary, the erosion of the coating by the molten metal increases, so the addition amount is limited to 30%.
[0007]
The balance is carbide such as WC, but these carbides complement the function and effect of the boride and provide the bond coat itself with molten metal corrosion resistance.
As the top coat ceramic, a ceramic having a small difference in thermal expansion coefficient from the metal portion as the base material is preferable, and a material having a linear expansion coefficient as large as possible is preferably selected. In the embodiment of the present invention, chromia having a large expansion coefficient is applied.
[0008]
The thickness of the top coat film is limited to 50 to 200 μm, because if the film thickness is excessively large, the residual stress increases and the film easily peels off inside the ceramic film or at the interface between the bond coat and the top coat ceramic (see Examples).
Further, B 2 O 3 generated on the surface of the bond coat is vitrified at the ceramic interface, and exhibits a strong adhesion. That is, in the present invention, a boric acid-containing glass material is produced by a boride-based cermet of a bond coat, and a strong adhesive force is imparted to the top coat.
[0009]
Furthermore, in the present invention, performing the impregnation treatment with an aqueous solution containing chromic acid as a main component after spraying an oxide ceramic as a top coat and performing the baking treatment densifies the ceramic film and suppresses the falling off of the film particles. That's why. H 2 CrO 4 as the main component , H 2 Cr 2 O 7 and the like cause a dehydration reaction by heating after impregnation, and turn into CrO 3 . CrO 3 is melted from about 200 ° C., and is oxidized to form Cr 2 O 3 while oxidizing the film, and sealing is performed. In this case, due to the oxidation of CrO 3 , Cr 2 O 3 adheres to the film and increases the film strength. Further, in the liquid containing ammonium molybdate, pH adjustment and sealing with molybdenum oxide can be performed to complement the sealing effect.
[0010]
【Example】
Examples 1 and 2 of the present invention are shown in Table 1 (top coat and bond coat components) and Table 2 (corrosion thermal shock test results after impregnation and firing treatment with an aqueous solution containing chromic acid as a main component after top coat spraying). Show.
No. 1 to No. No. 8 is an embodiment of the present invention. 9 to 12 are comparative examples. No. 1 to No. In Example 8, a cermet containing boride was sprayed as a bond coat to form a coating. The films sprayed with 50 μm, 100 μm, and 200 μm of Cr 2 O 3 as the top coat did not peel off at all in the erosion thermal shock test. When a 250 μm thick top coat was sprayed, partial partial peeling occurred for the first time due to residual stress in the coating.
[0011]
On the other hand, in Comparative Example No. 1 in which the bond coat was a WC type. 9 and Comparative Example Nos. In the case of the film No. 10, partial peeling was already observed when the film thickness was 200 μm or less. Also, in Comparative Example No. 1 in which ceramics were sprayed without a bond coat. In the case of the films 11 and 12, all were peeled regardless of the film thickness.
This indicates that the member of the present invention is excellent in corrosion resistance and peeling resistance to a molten metal bath.
[0012]
In this example, the result of using only chromia as the top coat material was used.In other examples, similar results were obtained with alumina, zirconia / yttria, spinel, and the like, and the effects of the present invention were confirmed. ing.
[0013]
[Table 1]
[Table 2]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the member for molten metal baths excellent in molten metal corrosion resistance and peeling resistance can be provided.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP01435792A JP3577598B2 (en) | 1992-01-29 | 1992-01-29 | Method for producing molten metal bath member having coating excellent in molten metal corrosion resistance and peeling resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP01435792A JP3577598B2 (en) | 1992-01-29 | 1992-01-29 | Method for producing molten metal bath member having coating excellent in molten metal corrosion resistance and peeling resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05209259A JPH05209259A (en) | 1993-08-20 |
| JP3577598B2 true JP3577598B2 (en) | 2004-10-13 |
Family
ID=11858824
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP01435792A Expired - Lifetime JP3577598B2 (en) | 1992-01-29 | 1992-01-29 | Method for producing molten metal bath member having coating excellent in molten metal corrosion resistance and peeling resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3577598B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3312709B2 (en) * | 1994-10-24 | 2002-08-12 | 新日本製鐵株式会社 | Immersion roll for continuous galvanizing |
| JPH10306362A (en) * | 1997-04-28 | 1998-11-17 | Nippon Steel Hardfacing Co Ltd | Member for hot dip metal bath in which composite sprayed coating excellent in corrosion resistance to hot dip metal and peeling resistance is formed |
| KR20030052921A (en) * | 2001-12-21 | 2003-06-27 | 재단법인 포항산업과학연구원 | Thermal spray coated rolls used in an aluminum pot of a continuous aluminum plating line |
| JP4408649B2 (en) * | 2003-04-30 | 2010-02-03 | Ｊｆｅスチール株式会社 | Dipping member for hot metal plating baths with excellent dross resistance |
| JP6516344B1 (en) * | 2018-12-25 | 2019-05-22 | 日鉄ハードフェイシング株式会社 | Method of producing in-bath roll and in-bath roll |
-
1992
- 1992-01-29 JP JP01435792A patent/JP3577598B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05209259A (en) | 1993-08-20 |
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