JP3302812B2 - Pre-nitriding method for chromium-containing alloy - Google Patents
Pre-nitriding method for chromium-containing alloyInfo
- Publication number
- JP3302812B2 JP3302812B2 JP02743494A JP2743494A JP3302812B2 JP 3302812 B2 JP3302812 B2 JP 3302812B2 JP 02743494 A JP02743494 A JP 02743494A JP 2743494 A JP2743494 A JP 2743494A JP 3302812 B2 JP3302812 B2 JP 3302812B2
- Authority
- JP
- Japan
- Prior art keywords
- alkali metal
- nitrate
- nitriding
- chromium
- nitrite
- 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.)
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Description
【０００１】[0001]
【産業上の利用分野】本発明はクロムを含有する各種合
金を窒化及び軟窒化処理する際の前処理方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretreatment method for nitriding and nitrocarburizing various alloys containing chromium.
【０００２】[0002]
【従来の技術及びその問題点】クロムを含有する各種合
金、例えば不銹鋼、耐熱鋼あるいは含ニッケル耐熱合金
からなるエンジン等の耐熱、耐摩耗の構造部材及びエン
ジンバルブ、ピストンリング等の耐熱、耐摩耗の機械部
材の耐摩耗性、耐疲労性をより高めるために、従来より
これら部材に窒化及び軟窒化処理が施されている。これ
ら部材表面に窒化及び軟窒化処理を施す際、部材表面に
クロム酸化物不働態皮膜が形成されていることが多く、
このような不働態膜が形成されているまま処理すると、
窒化及び軟窒化処理が阻害され、均一で充分な深さで窒
化処理されなくなる。2. Description of the Related Art Heat and wear resistant structural members of engines made of various alloys containing chromium, such as stainless steel, heat resistant steel or nickel containing heat resistant alloys, and heat and wear resistance of engine valves and piston rings. In order to further enhance the wear resistance and fatigue resistance of the mechanical members described above, nitriding and nitrocarburizing treatments have been conventionally applied to these members. When performing nitriding and nitrocarburizing treatment on the surface of these members, a chromium oxide passive film is often formed on the surface of the members,
If processing is performed while such a passivation film is formed,
The nitriding and nitrocarburizing treatment is hindered, and the nitriding treatment cannot be performed at a uniform and sufficient depth.
【０００３】そのため、部材表面にクロム酸化物不働態
皮膜が形成されている部材に熱処理を施す場合、これら
部材をある種の酸に浸漬、あるいはハロゲン元素を含む
有機及び無機化合物を部材表面に塗布するか、それら化
合物を処理炉内に導入あるいは処理部材と一緒に装入
し、ハロゲン元素を含む有機及び無機化合物の熱分解生
成物であるハロゲン化水素、ハロゲンガスの作用により
部材表面を活性化させて窒化及び軟窒化処理を容易なら
しめる方法が採られている。[0003] Therefore, when heat treatment is applied to members having a chromium oxide passivation film formed on the surface of the member, these members are immersed in a certain acid, or an organic or inorganic compound containing a halogen element is applied to the surface of the member. Alternatively, these compounds are introduced into the processing furnace or charged together with the processing components, and the surface of the components is activated by the action of hydrogen halide and halogen gas, which are the thermal decomposition products of organic and inorganic compounds containing halogen elements. Then, a method of facilitating nitriding and nitrocarburizing is adopted.
【０００４】しかしながら、窒化及び軟窒化処理を施す
部材の表面を活性化する方法として、酸に浸漬する方法
は、酸による腐食に伴って発生する水素を部材が吸収す
ることにより引き起される水素脆化の欠点を有する。ま
た、ハロゲンを含む有機及び無機化合物の熱分解生成物
であるハロゲン化水素、ハロゲンガスの腐食作用を行な
わしめる方法は、切欠き部、狭い隙間部、不貫通の細い
穴の内部にそれらのガスが侵入しにくいことによる不均
一な腐食の欠点、あるいは処理炉内部の構成部材がそれ
らのガスにより不必要に腐食される等の欠点を有する。However, as a method for activating the surface of a member to be subjected to nitriding and nitrocarburizing treatment, a method of immersing the member in an acid is a method in which the member absorbs hydrogen generated due to corrosion by the acid. It has the disadvantage of embrittlement. In addition, the method of performing the corrosive action of hydrogen halide and halogen gas, which are the thermal decomposition products of organic and inorganic compounds containing halogen, is based on the notch, the narrow gap, and the inside of the impervious narrow hole. Has the disadvantage of non-uniform corrosion due to the difficulty of infiltration, and the disadvantage that components inside the processing furnace are unnecessarily corroded by these gases.
【０００５】本発明の目的は、従来の如く、酸による水
素脆化の問題、及びハロゲン化水素、ハロゲンガスの作
用を用いる場合の不均一腐食及び不必要な腐食問題を伴
わない、クロム含有合金よりなる部材の表面を効果的に
活性化し、もって良好な窒化及び軟窒化処理を行ない得
る前処理方法を提供するにある。[0005] It is an object of the present invention to provide a chromium-containing alloy which is free from the problems of hydrogen embrittlement due to acids and non-uniform corrosion and unnecessary corrosion when using the action of hydrogen halide and halogen gas. It is an object of the present invention to provide a pretreatment method capable of effectively activating the surface of a member made of the material and performing good nitriding and nitrocarburizing treatment.
【０００６】[0006]
【問題点を解決するための手段】本発明では、クロム含
有合金表面を窒化及び軟窒化処理する際の前処理方法で
あって、該合金を、水酸化アルカリ金属、硝酸アルカリ
金属及び亜硝酸アルカリ金属の少なくとも１種を含んだ
溶融塩に浸漬することを特徴とする。本発明において、
水酸化アルカリ金属としては水酸化リチウム、水酸化ナ
トリウム及び水酸化カリウムから選ばれるいずれか１種
又は２種以上、硝酸アルカリ金属としては硝酸リチウ
ム、硝酸ナトリウム及び硝酸カリウムから選ばれるいず
れか１種又は２種以上、亜硝酸アルカリ金属としては亜
硝酸リチウム、亜硝酸ナトリウム及び亜硝酸カリウムか
ら選ばれるいずれか１種又は２種以上であり、これらが
単体又は２種以上含まれる溶融塩が用いられる。According to the present invention, there is provided a pretreatment method for nitriding and nitrocarburizing the surface of a chromium-containing alloy, wherein the alloy is formed of an alkali metal hydroxide, an alkali metal nitrate and an alkali nitrite. It is characterized by being immersed in a molten salt containing at least one metal. In the present invention,
The alkali metal hydroxide is any one or two or more selected from lithium hydroxide, sodium hydroxide and potassium hydroxide, and the alkali metal nitrate is any one or two selected from lithium nitrate, sodium nitrate and potassium nitrate. The alkali metal nitrite is at least one selected from the group consisting of lithium nitrite, sodium nitrite and potassium nitrite, and a molten salt containing one or more of these is used.
【０００７】[0007]
【作用】本発明では、クロム含有の合金よりなる部材を
前記したような溶融塩中に浸漬することにより、当該部
材表面に成形されているクロム酸化物不働態皮膜が、
（１）水酸化アルカリ金属との反応によりクロム酸アル
カリ金属化合物を生成し、溶融塩中に溶解する、及び／
又は（２）硝酸アルカリ金属、亜硝酸アルカリ金属との
反応により高次の酸化物に移行し、溶融塩中に過不働態
溶解する、ことにより、当該部材表面に活性化された面
が露出し、窒化及び軟窒化作用を容易ならしめる結果、
熱処理を促進させることになる。According to the present invention, a member made of a chromium-containing alloy is immersed in a molten salt as described above, so that a chromium oxide passive film formed on the surface of the member becomes:
(1) producing an alkali metal chromate compound by reaction with an alkali metal hydroxide and dissolving it in a molten salt; and / or
Or (2) a transition to a higher oxide by a reaction with an alkali metal nitrate or an alkali metal nitrite, and dissolving in a molten salt in a passive state, so that an activated surface is exposed on the surface of the member. As a result of facilitating the nitriding and nitrocarburizing action,
Heat treatment will be accelerated.
【０００８】本発明においては、被処理合金を、水酸化
アルカリ金属、硝酸アルカリ金属及び亜硝酸アルカリ金
属の少なくとも１種を含んだ溶融塩に浸漬することから
なり、より具体的には、ＬｉＯＨ，ＮａＯＨ，ＫＯＨ
（水酸化アルカリ金属）、ＬｉＮＯ3，ＮａＮＯ3，ＫＮ
Ｏ3（硝酸アルカリ金属）、ＬｉＮＯ2，ＮａＮＯ2，Ｋ
ＮＯ2（亜硝酸アルカリ金属）の単体、もしくは２種以
上を含んだ溶融塩に浸漬するものであり、それらの好ま
しい例として、ＬｉＯＨ，ＮａＯＨ，ＫＯＨのいずれか
から選ばれる１種又は２種以上（水酸化アルカリ金属グ
ループ単独）、ＬｉＯＨ，ＮａＯＨ，ＫＯＨのいずれか
から選ばれる１種又は２種以上と、ＬｉＮＯ3，ＮａＮ
Ｏ3，ＫＮＯ3のいずれかから選ばれる１種又は２種以上
との組合せ（水酸化アルカリ金属グループ＋硝酸アルカ
リ金属グループ）、ＬｉＯＨ，ＮａＯＨ，ＫＯＨのいず
れかから選ばれる１種又は２種以上と、ＬｉＮＯ3，Ｎ
ａＮＯ3，ＫＮＯ3のいずれかから選ばれる１種又は２種
以上と、ＬｉＮＯ2，ＮａＮＯ2，ＫＮＯ2のいずれかか
ら選ばれる１種又は２種以上との組合せ（水酸化アルカ
リ金属グループ＋硝酸アルカリ金属グループ＋亜硝酸ア
ルカリ金属グループ）たものが考えられる。このよう
に、本発明に使用する溶融塩としてその中に水酸化アル
カリ金属が含まれることが好ましい。In the present invention, the alloy to be treated is immersed in a molten salt containing at least one of an alkali metal hydroxide, an alkali metal nitrate and an alkali metal nitrite, and more specifically, LiOH, NaOH, KOH
(Alkali metal hydroxide), LiNO 3 , NaNO 3 , KN
O 3 (alkali metal nitrate), LiNO 2 , NaNO 2 , K
It is immersed in a molten salt containing a simple substance of NO 2 (alkali nitrite) or two or more kinds thereof. Preferred examples thereof include one or more kinds selected from LiOH, NaOH and KOH. (Alone alkali metal hydroxide group), one or more selected from LiOH, NaOH and KOH, and LiNO 3 , NaN
Combination with one or more selected from O 3 and KNO 3 (alkali metal hydroxide group + alkali metal nitrate group), one or more selected from LiOH, NaOH and KOH And LiNO 3 , N
a combination of one or more selected from aNO 3 and KNO 3 and one or more selected from LiNO 2 , NaNO 2 and KNO 2 (alkali metal hydroxide group + nitric acid (Alkali metal group + alkali metal nitrite group). Thus, the molten salt used in the present invention preferably contains an alkali metal hydroxide.
【０００９】なお、水酸化アルカリ金属グループ単独の
場合の溶融塩温度範囲は、３００〜６５０℃、水酸化ア
ルカリ金属グループ＋硝酸アルカリ金属グループを組み
合わせる場合、水酸化アルカリ金属グループの量は１０
〜４０重量％とし、その温度範囲は３００〜５００℃、
また水酸化アルカリ金属グループ＋硝酸アルカリ金属グ
ループ＋亜硝酸アルカリ金属グループを組み合わせる場
合、水酸化アルカリ金属グループの量は１０〜４０重量
％とし、その温度範囲は２５０〜４５０℃が適当であ
る。When the alkali metal hydroxide group alone is used, the molten salt temperature range is 300 to 650 ° C., and when the alkali metal hydroxide group + alkali metal nitrate group is combined, the amount of alkali metal hydroxide group is 10%.
~ 40% by weight, the temperature range is 300 ~ 500 ° C,
When the alkali metal hydroxide group + alkali metal nitrate group + alkali metal nitrite group is combined, the amount of the alkali metal hydroxide group is 10 to 40% by weight, and the temperature range is suitably from 250 to 450.degree.
【００１０】[0010]
【実施例１】水酸化カリウム４０重量％、水酸化ナトリ
ウム４０重量％、硝酸ナトリウム２０重量％、温度３５
０℃の溶融塩中にＳＵＨ １１材の試験片を２０分間浸
漬し、前処理を行なったものと、行なわなかったものと
に、５５０℃×６時間のアンモニアガス窒化処理を行な
った。その結果、前処理を行なった試験片には、８８μ
ｍの均一な全窒化層が形成されたのに対し、前処理を行
なわなかった試験片には、３３μｍの均一な全窒化層が
形成されたにすぎなかった。Example 1 Potassium hydroxide 40% by weight, sodium hydroxide 40% by weight, sodium nitrate 20% by weight, temperature 35
A test piece of SUH 11 material was immersed in a molten salt at 0 ° C. for 20 minutes, and a pre-treated one and a non-pretreated one were subjected to an ammonia gas nitriding treatment at 550 ° C. × 6 hours. As a result, 88 μm
While a uniform nitrided layer having a thickness of m was formed, the test piece that had not been subjected to the pretreatment had only a uniform total nitrided layer having a thickness of 33 μm.
【００１１】[0011]
【実施例２】水酸化カリウム４０重量％、水酸化ナトリ
ウム４０重量％、硝酸ナトリウム２０重量％、温度３５
０℃の溶融塩中にＳＵＨ ３５材の試験片を２０分間浸
漬し、前処理を行なったものと、行なわなかったものと
に、５７０℃×３０分の塩浴軟窒化処理を行なった。そ
の結果、前処理を行なった試験片には、２３μｍの均一
な窒化物層が形成されたのに対し、前処理を行なわなか
った試験片には、０〜１０μｍの窒化物層が不均一に形
成された。Example 2 40% by weight of potassium hydroxide, 40% by weight of sodium hydroxide, 20% by weight of sodium nitrate, temperature 35
A test piece of SUH 35 material was immersed in a molten salt at 0 ° C. for 20 minutes, and a pretreatment and a non-treated test piece were subjected to salt bath soft nitriding at 570 ° C. for 30 minutes. As a result, a uniform nitride layer of 23 μm was formed on the test piece subjected to the pretreatment, whereas a non-uniform nitride layer of 0 to 10 μm was formed on the test piece without the pretreatment. Been formed.
【００１２】[0012]
【実施例３】実施例２と同一の３５０℃の溶融塩中に、
ＳＵＳ ２０１材の試験片を２０分間浸漬し、前処理を
行なったものと、行なわなかったものとに、５７０℃×
３０分の塩浴軟窒化処理を行なった。その結果、前処理
を行なった試験片には、１７μｍの均一な窒化物層が形
成されたのに対し、前処理を行なわなかった試験片に
は、０〜１０μｍの窒化物層が不均一に形成された。Example 3 In the same molten salt at 350 ° C. as in Example 2,
A test piece of SUS 201 material was immersed for 20 minutes and subjected to pretreatment and non-pretreated at 570 ° C. ×
A salt bath nitrocarburizing treatment was performed for 30 minutes. As a result, a uniform nitride layer of 17 μm was formed on the pre-treated test piece, whereas a non-uniform nitride layer of 0 to 10 μm was formed on the non-pre-treated test piece. Been formed.
【００１３】[0013]
【実施例４】硝酸ナトリウム３５重量％、硝酸カリウム
３５重量％、水酸化ナトリウム３０重量％、温度３００
℃の溶融塩中に、ＳＵＳ ２０１材の試験片を２０分間
浸漬し、前処理を行なったものと、行なわなかったもの
とに、５７０℃×２０分の塩浴軟窒化処理を行なった。
その結果、前処理を行なった試験片には、１５μｍの均
一な窒化物層が形成されたのに対し、前処理を行なわな
かった試験片には、０〜５μｍの窒化物層が不均一に形
成された。Example 4 35% by weight of sodium nitrate, 35% by weight of potassium nitrate, 30% by weight of sodium hydroxide, temperature of 300
A test piece of SUS 201 material was immersed in a molten salt at 20 ° C. for 20 minutes, and a pretreatment and a non-treated test piece were subjected to salt bath soft nitriding at 570 ° C. for 20 minutes.
As a result, a uniform nitride layer of 15 μm was formed on the pre-treated test piece, whereas a non-uniform nitride layer of 0 to 5 μm was formed on the non-pre-treated test piece. Been formed.
【００１４】[0014]
【実施例５】水酸化ナトリウム５０重量％、水酸化カリ
ウム５０重量％、温度４００℃の溶融塩中に、ＳＵＳ
２０１材の試験片を２０分間浸漬し、前処理を行なった
ものと、行なわなかったものとに、５７０℃×２０分の
塩浴軟窒化処理を行なった。その結果、前処理をおこな
った試験片には１５μｍの均一な窒化物層が形成された
のに対し、前処理を行なわなかった試験片には０〜５μ
ｍの窒化物層が不均一に形成された。Embodiment 5 In a molten salt of 50% by weight of sodium hydroxide and 50% by weight of potassium hydroxide at a temperature of 400 ° C., SUS
201 specimens were immersed for 20 minutes and subjected to pretreatment and those not subjected to salt bath soft nitriding at 570 ° C. for 20 minutes. As a result, a uniform nitride layer having a thickness of 15 μm was formed on the test piece subjected to the pretreatment, whereas the test piece not subjected to the pretreatment was 0 to 5 μm.
m was formed unevenly.
【００１５】[0015]
【実施例６】硝酸カリウム３５重量％、亜硝酸ナトリウ
ム３５重量％、水酸化ナトリウム３０重量％、温度３０
０℃の溶融塩中に、ＳＵＳ ２０１材の試験片を２０分
間浸漬し、前処理を行なったものと、行なわなかったも
のとに、５７０℃×２０分の塩浴軟窒化処理を行なっ
た。その結果、前処理を行なった試験片には１５μｍの
均一な窒化物層が形成されたのに対し、前処理を行なわ
なかった試験片には０〜１０μｍの窒化物層が不均一に
形成された。以上、実施例１〜６の条件及び結果を表１
及び表２に示す。Embodiment 6 Potassium nitrate 35% by weight, sodium nitrite 35% by weight, sodium hydroxide 30% by weight, temperature 30
A test piece of SUS 201 material was immersed in a molten salt at 0 ° C. for 20 minutes, and a pretreatment and a non-treated test piece were subjected to salt bath soft nitriding at 570 ° C. for 20 minutes. As a result, a 15 μm uniform nitride layer was formed on the pre-treated test pieces, whereas a 0-10 μm nitride layer was formed non-uniformly on the non-pre-treated test pieces. Was. As described above, the conditions and results of Examples 1 to 6 are shown in Table 1.
And Table 2.
【００１６】[0016]
【表１】 [Table 1]
【００１７】[0017]
【表２】 [Table 2]
【００１８】[0018]
【発明の効果】以上のような本発明によれば、クロム含
有合金表面にクロム酸化物不働態皮膜が形成されている
場合にも、これら部材表面を従来の如き問題点を有さず
に活性化することができ、その後の窒化及び軟窒化処理
が著しく容易かつ均一に促進される。According to the present invention as described above, even when a chromium oxide passivation film is formed on the surface of a chromium-containing alloy, the surface of these members can be activated without having any problems as in the prior art. And the subsequent nitriding and nitrocarburizing treatment are remarkably easily and uniformly promoted.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) C23C 8/02 C23C 8/24 C23C 8/26 C23C 8/30 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. 7 , DB name) C23C 8/02 C23C 8/24 C23C 8/26 C23C 8/30
Claims (2)
理する際の前処理方法であって、該合金を、水酸化アル
カリ金属、硝酸アルカリ金属及び亜硝酸アルカリ金属の
少なくとも１種を含んだ溶融塩に浸漬することを特徴と
するクロム含有合金の窒化前処理方法。A pretreatment method for nitriding and nitrocarburizing a surface of a chromium-containing alloy, the method comprising melting the alloy containing at least one of an alkali metal hydroxide, an alkali metal nitrate and an alkali metal nitrite. A method for pre-nitriding a chromium-containing alloy, characterized by immersing in a salt.
酸化リチウム、水酸化ナトリウム及び水酸化カリウムか
ら選ばれるいずれか１種又は２種以上、硝酸アルカリ金
属が硝酸リチウム、硝酸ナトリウム及び硝酸カリウムか
ら選ばれるいずれか１種又は２種以上、亜硝酸アルカリ
金属が亜硝酸リチウム、亜硝酸ナトリウム及び亜硝酸カ
リウムから選ばれるいずれか１種又は２種以上であり、
これらが単体又は２種以上含まれることを特徴とする請
求項１記載のクロム含有合金の窒化前処理方法。2. As the molten salt, the alkali metal hydroxide is at least one selected from lithium hydroxide, sodium hydroxide and potassium hydroxide, and the alkali metal nitrate is selected from lithium nitrate, sodium nitrate and potassium nitrate. Any one or two or more, wherein the alkali metal nitrite is any one or two or more selected from lithium nitrite, sodium nitrite and potassium nitrite,
The method for pre-nitriding a chromium-containing alloy according to claim 1, wherein these are contained alone or in combination of two or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02743494A JP3302812B2 (en) | 1994-01-31 | 1994-01-31 | Pre-nitriding method for chromium-containing alloy |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02743494A JP3302812B2 (en) | 1994-01-31 | 1994-01-31 | Pre-nitriding method for chromium-containing alloy |
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| Publication Number | Publication Date |
|---|---|
| JPH07216527A JPH07216527A (en) | 1995-08-15 |
| JP3302812B2 true JP3302812B2 (en) | 2002-07-15 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP02743494A Expired - Lifetime JP3302812B2 (en) | 1994-01-31 | 1994-01-31 | Pre-nitriding method for chromium-containing alloy |
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| JP6111126B2 (en) * | 2013-04-12 | 2017-04-05 | パーカー熱処理工業株式会社 | Salt bath soft nitriding method |
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| JPH07216527A (en) | 1995-08-15 |
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