JP4302852B2 - Method for measuring surface oxide of metal material and X-ray diffractometer - Google Patents

Description

【００２７】
この結果、10〜80g/m²のFe₃O₄ 付着量に対してσ_d として2.0g/m² が得られ、十分な精度でFe₃O₄ 量(g/m²)を定量できることが分かった。
次に、スケール組成がマグネタイト(Fe₃O₄) およびウスタイト(FeO) の２成分である鋼板試料を用いて、FeO の(220) 面の回折Ｘ線強度を測定し、下記(1) 、(2) の手順でスケール中 FeO濃度とFeO の回折Ｘ線強度との関係を求めた。
【００２８】
(1) スケール中 FeO濃度の測定：
スケール組成比の決定は、用いた鋼板の断面について走査電子顕微鏡(SEM) の反射電子像を数箇所測定し、画像解析を行うことによりスケール中の析出物や孔を除去しFe₃O₄ と FeOの面積比を求め、それぞれの密度を乗することにより行った。
【００２９】
すなわち、例えば、 SEM像でFe₃O₄ の厚さが５μｍで、 FeOの厚さが１μｍで、観察した範囲が20μｍの場合、Fe₃O₄ の面積は１×10^-6(cm²) で、FeO の面積は 0.2×10^-6(cm²) となる。
断面と直交する方向にｈcmの幅をとれば、体積はそれぞれ１×10^-6ｈ(cm³) および 0.2×10^-6ｈ(cm³) である。
【００３０】
また、Fe₃O₄ および FeOの密度は、それぞれ5.0g/cm³および5.7g/cm³であるので、それぞれの質量は 5.0×10^-6ｈ(g) および1.14×10^-6ｈ(g) である。
したがって、上記した試料の場合、スケール全体に対する FeOの濃度は、18.6mass％となる。
上記の測定を複数の試料について行った結果、これら試料のスケール中の FeO濃度は０〜70mass％であった。
【００３１】
(2) スケール中 FeO濃度とFeO の回折Ｘ線強度との関係の調査：
上記で用いた鋼板試料において、高次酸化物であるFe₃O₄ はスケールの表層側（表面酸化物層における上層）に存在し、低次酸化物である FeOは下地鋼板側（表面酸化物層における下層）に存在する。
この結果、下層に存在する FeOからの回折Ｘ線の一部は表層のFe₃O₄ に吸収される。
【００３２】
このため、上記した鋼板試料のFe₃O₄[(511) 面] の回折Ｘ線強度：Ｉ(Fe₃O₄) と前記式(1) の検量線を用いて鋼板試料のFe₃O₄ の量：Ｗ（Fe₃O₄)(g/m²)を求め、下記式(3) に基づき、FeO の(220) 面の回折Ｘ線強度：Ｉ(FeO) を、Fe₃O₄ による質量吸収係数：μ(m²/g)で補正した回折Ｘ線強度補正値：Ｉ(FeO)._com を求めた。
【００３３】
Ｉ(FeO)._com ＝Ｉ(FeO) ／exp[−μ・Ｗ(Fe₃O₄) ] ………(3)
上記式(3) 中、μ＝67.5(m²/g)を示す。
次に、上記した複数の試料についてスケール中の FeOの量：Ｗ（FeO)(g/m²)と吸収補正したFeO の(220) 面の回折Ｘ線強度補正値：Ｉ(FeO)._com との関係を求め、図４および下記式(4) で近似される検量線を得た。
【００３４】
Ｗ（FeO)＝ｇ（Ｉ(FeO)._com ）＝1.57×10^-4〔Ｉ(FeO)._com 〕² −1.73×10^-2〔Ｉ(FeO)._com 〕………(4)
次に、前記した式(2) と同様の計算式で、検量線の精度を求めた結果、σ_d は3.4(g/m²) であり、十分な精度で下層のFeO を分析できることが分かった。
さらに、得られたFeO 量 (g/m²) 、Fe₃O₄ 量(g/m²)からスケール中のFeO 濃度を求めた結果を、化学分析値と対比して図５に示す。
【００３５】
FeO 濃度もσ_d ＝3.1 mass％で分析できることが分かった。
以下、本発明における金属材表面酸化物の測定方法を、上記した鋼板試料の表面酸化物層における上層のFe₃O₄ および下層のFeO の測定を例として説明する。すなわち、Ｘ線管球からのＸ線を鋼板表面に照射し、鋼板表面から放射されるFe₃O₄ およびFeO それぞれの回折Ｘ線強度Ｉ(Fe₃O₄) 、Ｉ(FeO) を測定する。
【００３６】
次に、鋼板試料表面の酸化物層の内、上層に存在するFe₃O₄ の存在量Ｗ(Fe₃O₄) を、上記で得られたFe₃O₄ の回折Ｘ線強度Ｉ(Fe₃O₄) と、予め求めたFe₃O₄ の存在量Ｗ（Fe₃O₄)とFe₃O₄ の回折Ｘ線強度Ｉ（Fe₃O₄)との関係を示す検量線である前記した式(1) とから求める。
次に、上記で得られたFeO の(220) 面の回折Ｘ線強度Ｉ(FeO) をFe₃O₄ の存在量Ｗ(Fe₃O₄) および前記式(3) の両者に基づき補正した回折Ｘ線強度補正値：Ｉ(FeO)._com を求める。
【００３７】
上記で得られた回折Ｘ線強度補正値：Ｉ(FeO)._com および前記式(4) の検量線からスケール中のFeO の存在量Ｗ(FeO) さらにはFeO 濃度を求めることができる。
以上、本発明の金属板表面酸化物の測定方法を、鋼板試料におけるFe₃O₄ およびFeO の測定を例として説明したが、本発明によれば、図１に例示したＸ線回折装置を金属板の通板（搬送）ラインに設置することによって、金属板表面の各種酸化物の組成と量を同時にオンラインで迅速かつ正確に測定することができる。
【００３８】
すなわち、本発明のＸ線回折装置を、例えば鋼板試料におけるFe₃O₄ およびFeO の測定装置として用いる場合、Ｘ線回折装置は、下記(1) 〜(4) の各機器から構成される。
(1) 鋼板試料表面にＸ線を照射するＸ線管球２
(2) 取り出し角が固定された回折Ｘ線検出器3A、3B
(3) 計数回路部8A
計数回路部8Aにおいては、鋼板試料表面層から放射されるFe₃O₃ 、FeO それぞれの回折Ｘ線強度を計数する。
【００３９】
(4) 演算手段9A、9B
演算手段9Aにおいては、計数回路部8Aで計数された鋼板試料表面層のFe₃O₄ の回折Ｘ線強度Ｉ(Fe₃O₄) および予め求めた前記した式(1) で例示される検量線に基づき、鋼板試料表面層上層のFe₃O₄ の存在量Ｗ(Fe₃O₄) を求める。
すなわち、演算手段9Aとしては、前記した式(1) で例示される検量線を予め記憶し、計数回路部8Aで計数された鋼板試料表面層のFe₃O₄ の回折Ｘ線強度Ｉ(Fe₃O₄) に基づいて鋼板試料表面層上層のFe₃O₄ の存在量Ｗ(Fe₃O₄) を求める記憶・演算装置を用いることができる。
【００４０】
演算手段9Bにおいては、<1> 上記で得られたＷ(Fe₃O₄) 、<2> 計数回路部8Aで計数された鋼板試料表面層のFeO の回折Ｘ線強度Ｉ(FeO) および<3> 前記した式(3) で例示される補正式から、上層の酸化物Fe₃O₄ の回折Ｘ線吸収率で補正した酸化物FeO の回折Ｘ線強度：Ｉ(FeO)._com を求める。
次に、演算手段9Bにおいては、上記で得られた回折Ｘ線強度：Ｉ(FeO)._com と、予め求めた前記した式(4) で例示される検量線に基づき、鋼板試料表面層下層のFeO の存在量Ｗ(FeO) を求める。
【００４１】
すなわち、演算手段9Bとしては、前記した式(3) で例示される補正式および式(4) で例示される検量線の両者を予め記憶し、計数回路部8Aで計数された鋼板試料表面層のFeO の回折Ｘ線強度Ｉ(FeO) および演算手段9Aで求められた鋼板試料表面層上層のFe₃O₄ の存在量Ｗ(Fe₃O₄) に基づいて鋼板試料表面層下層のFeO の存在量Ｗ(FeO) を求める記憶・演算装置を用いることができる。
【００４２】
本発明においては、さらに下記(5) 〜(7) の機器を配設することによって、前記した回折Ｘ線検出器（3A、3B）と金属材の試料Ｓとの距離の経時的変化による回折Ｘ線強度の変化を補正し、さらに正確な酸化物の測定が可能となる。
(5) 蛍光Ｘ線検出器3C
取り出し角βが固定された蛍光Ｘ線検出器3C
(6) 計数回路部8B
蛍光Ｘ線検出器3Cで検出された蛍光Ｘ線強度を計数する計数回路部8B
(7) 演算手段9C
演算手段9Cにおいては、計数回路部8Bで計数された蛍光Ｘ線強度に基づき回折Ｘ線検出器（3A、3B）と金属材との距離の経時的変化によるＡ成分、Ｂ成分それぞれの回折Ｘ線強度の計数値の経時的変化を補正する。
【００４３】
以下、鋼板表面の酸化物の測定を例として、上記した蛍光Ｘ線強度による補正方法について述べる。
蛍光Ｘ線の取り出し角度をβとすると、測定中に鋼板が基準位置に対してｄだけ垂直方向に動いた時、蛍光Ｘ線検出器と鋼板との距離はｄ/sinβ変化する。
蛍光Ｘ線検出器と測定円の中心との距離をＬとすると、蛍光Ｘ線強度比は下記式(5) で示される。
【００４４】
Ｉ₁/Ｉ₀ ＝Ｌ²/（Ｌ＋ｄ/sinβ）² ………(5)
上記式(5) 中、
Ｉ₀ ：鋼板が基準位置にある時の蛍光Ｘ線強度
Ｉ₁ ：鋼板が垂直方向にｄだけ基準位置よりずれている時の蛍光Ｘ線強度
を示す。
【００４５】
すなわち、例えば鋼板のマトリックスであるFeの蛍光Ｘ線強度を得ることによって、前記式(5) によってｄを求めることができる。
回折Ｘ線の検出角度をδとすると、Ｌ、ｄ、δは全て既知のパラメータであるので、下記式(6) から回折Ｘ線の真の強度Ｔ₁ を求めることができる。
Ｔ₁ ＝Ｔ₀ ・Ｌ²/（Ｌ＋ｄ/sinδ）² ………(6)
なお、上記式(6) 中、
Ｔ₀ ：測定された回折Ｘ線の見掛け上の強度
Ｔ₁ ：測定された回折Ｘ線の真の強度
を示す。
【００４６】
上記した回折Ｘ線の真の強度Ｔ₁ の演算方法を、前記した回折Ｘ線強度：Ｉ(Fe₃O₄) および回折Ｘ線強度：Ｉ(FeO) に適用し、鋼板が基準位置にある場合のＩ(Fe₃O₄) およびＩ(FeO) を求め、得られたそれぞれの値と、前記した式(1) 、(3) 、(4) とから、さらに正確なFe₃O₄ 、FeO の存在量を求めることができる。なお、前記した５種類の記憶・演算装置は、単一（一台）の記憶・演算装置とすることができる。
【００４７】
【実施例】
以下、本発明を実施例に基づいてさらに具体的に説明する。
熱間圧延設備→酸洗設備→冷間圧延設備の工程順序からなる冷延鋼板の製造ラインにおいて、酸洗設備の入口側に前記した図１に示すＸ線回折装置を設置し、前記した方法で、鋼板表面に存在するスケール中のFe₃O₃ 、FeO の存在量を測定した。
【００４８】
なお、上記した測定においては、図１に示す蛍光Ｘ線検出器3Cによって鋼板のマトリックスであるFeの蛍光Ｘ線強度を測定し、回折Ｘ線検出器（3A、3B）と鋼板試料Ｓとの距離の経時的変化による回折Ｘ線強度の変化を補正し、距離補正後の回折Ｘ線強度：Ｉ(Fe₃O₄) および回折Ｘ線強度：Ｉ(FeO) に基づきスケール中のFe₃O₃ 、FeO の存在量を測定した。
【００４９】
また、本実施例においては、得られた測定結果に基づき酸洗設備への通板速度を制御した。
なお、Ｘ線回折装置の測定条件は、下記の通りとした。
照射Ｘ線：Cr-Kα線（波長：0.229nm ）
Fe₃O₃ の回折角度２θ：90°
FeO の回折角度２θ ：64°
この結果、上記した制御を行うことによって鋼板の酸洗不良の発生量を、従来の１／２に低減することが可能となった。
【００５０】
【発明の効果】
本発明によれば、金属板などの金属材の表面に存在する酸化物の組成と存在量を迅速かつ正確に非破壊で測定し、金属材表面酸化物の量を制御することが可能となった。
【図面の簡単な説明】
【図１】本発明のＸ線回折装置の一例を示す説明図(a) およびＸ線管球−Ｘ線検出器収納部の一例を示す説明図(b) である。
【図２】鋼板試料のＸ線回折結果（θ−２θ方式）を示すグラフである。
【図３】スケール(Fe₃O₄) 量とFe₃O₄[(511) 面] の回折Ｘ線強度との関係を示すグラフである。
【図４】スケール中の FeO量と吸収補正したFeO[(220) 面] の回折Ｘ線強度補正値との関係を示すグラフである。
【図５】スケール中の FeO濃度の化学分析値とＸ線回折法による分析値との関係を示すグラフである。
【符号の説明】
１ Ｘ線管球−Ｘ線検出器収納部
２ Ｘ線管球
３、3A、3B 回折Ｘ線検出器（：Ｘ線検出器）
3C 蛍光Ｘ線検出器
４ 高電圧発生部
５ 波高分析器
６ Ｘ線検出器高電圧印加装置
７ 測定角度コントローラ
8A、8B 計数回路部
9A、9B、9C、9D、9E 演算手段
10 プリンタ
11 レコーダ
12 デイスプレー
13 送水装置
15A 、15B 、15C ソーラースリット
Ｓ 試料[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring a metal material surface oxide such as an oxide formed on the surface of a steel plate in a steel plate manufacturing process, for example, and an X-ray diffractometer used in the measurement method.
[0002]
[Prior art]
Oxide (scale) composed of Fe ₃ O ₄ , FeO, etc. formed on the surface of the steel plate in the steel plate manufacturing process is either by spraying high-pressure water on the surface of the steel plate or by passing the steel plate into an acidic solution and washing it. Remove.
Since the composition and amount of oxide on the surface of the steel plate have a great influence on the properties of the final product, it is important to accurately measure and control the composition and amount of oxide in the manufacturing process.
[0003]
The following method is used as a method for measuring the composition and amount of the oxide.
That is, one method is a method in which bromomethanol is used to peel the oxide on the surface of the steel plate from the surface, and the powder is pulverized in a mortar and X-ray diffraction is performed.
In this case, quantification is performed based on several types of powder samples (standard samples) with different mixing ratios of magnetite and wustite.
[0004]
However, the above-described method has a problem that it takes a long time for sample preparation and the like, and furthermore, the oxide distribution state on the steel sheet surface cannot be known.
As another method, a method is used in which the steel plate itself on which the oxide is formed is X-ray diffracted and quantified by comparison with a standard sample.
However, in the case of the method described above, if the scale has a multilayer structure, absorption of diffracted X-rays from the lower layer occurs in the surface layer, and measurement of the lower layer is impossible.
[0005]
Furthermore, since metallic iron exists in the scale, the correct scale thickness cannot be obtained from the attenuation factor of the diffracted X-rays from the base steel plate.
That is, in the case of the above-described method, there is a problem that the composition and amount of the surface oxide having a multilayer structure cannot be measured accurately.
The surface composition measurement method using X-rays as an excitation source is widely used industrially. For example, there is a method of measuring the composition and thickness of a plating layer using fluorescent X-rays. It is possible to determine the composition ratio of zinc and iron in the above, but it is necessary to perform structural analysis in order to determine the amount of iron oxide for each type, which is not possible with the above method.
[0006]
That is, conventionally, it is possible to measure the composition and amount of an oxide on the surface of a metal material such as a steel sheet, which solves the above-described problem, and a method for measuring the surface oxide of a metal material that serves as an index for scale control and the measurement method There has been a demand for an X-ray diffractometer to be used for the above.
[0007]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems of the prior art, and enables a metal material surface oxide capable of measuring the composition and amount of an oxide present on the surface of a metal material such as a steel plate quickly and accurately in a nondestructive manner. It is an object of the present invention to provide an X-ray diffractometer suitably used for the measurement method.
[0008]
[Means for Solving the Problems]
In the first invention, the metal material having the oxide A as the upper layer of the surface oxide layer and the oxide B as the lower layer of the surface oxide layer is irradiated with characteristic X-rays or monochromatic X-rays, the diffracted X-ray intensity I _B of the diffracted X-ray intensity I _a and the oxide B of oxide a to be emitted was measured, and a diffracted X-ray intensity I _a of the oxide a obtained in advance with a calibration curve, surface oxides determine the abundance W _a layer upper layer of oxide a, further, oxides abundance of diffracted X-ray absorption factor the oxide a oxide B diffracted X-ray intensity I _B by the upper layer of the oxide a and B The diffracted X-ray intensity of oxide B: I _B.com is obtained by correcting with W _A, and the abundance W _B of oxide B in the lower layer of the surface oxide layer is obtained from I _B.com and the calibration curve obtained in advance. This is a method for measuring the surface oxide of a metal material.
[0009]
According to a second aspect of the present invention, there is provided a metal material surface oxide for measuring a surface oxide of a metal material having an oxide A as an upper layer of the surface oxide layer and an oxide B as a lower layer of the surface oxide layer during transport of the metal material. A measurement method using an X-ray diffractometer with a fixed diffraction angle 2θ and a fluorescent X-ray detector with a fixed extraction angle β with respect to a reference position of the metal material. and it was irradiated with X-rays, as well as measuring the diffracted X-ray intensity I _B of the diffracted X-ray intensity I _a and the oxide B of oxide a to be emitted from the metal material, the fluorescent X of matrix metal which is emitted from a metal material By measuring the change over time of the line intensity I _FX , the displacement from the reference position of the metal material is obtained, and the above-mentioned diffraction X-ray intensities I _A and I _B are corrected based on the change. and a correction value I _A.0 diffracted X-ray intensity I _a previously determined with a calibration curve, Determine the abundance W _A of oxide A layer, further, the diffracted X-oxides B correction value I _B.0 of the diffracted X-ray intensity I _B of the oxide B obtained above by the upper layer of the oxide A diffracted X-ray intensity of the corrected oxide B with the linear absorption rate and abundance W _a of the oxide a: seek _I B.0.com, from a previously obtained calibration curve with the I _B.0.Com a measuring method of a metal material surface oxides and obtains the abundance W _B of the lower side of the oxide B.
[0010]
The third invention comprises an X-ray tube 2 that irradiates a sample surface with X-rays, two or more diffracted X-ray detectors 3A and 3B each having a fixed take-off angle, and the diffracted X-ray detector. A counting circuit unit 8A for counting the diffracted X-ray intensities of the A component and B component of the sample surface layer radiated from the sample surface layer detected by each of 3A and 3B, and a sample counted by the counting circuit unit 8A calculation means 9A for determining the abundance W _a of the a component of the sample surface layer based on both of the diffracted X-ray intensity I _a and previously obtained calibration curve of the a component of the surface layer, the sample was counted in the counting circuit section 8A have a calculation means 9B for determining the abundance W _B of the B component of the diffracted X-ray intensity I _B and previously obtained sample surface layer based on both of the calibration curve of the B component of the surface layer, further, the computing means (9B) but a diffraction X-ray absorptivity diffracted X-ray intensity I _B of the B component of the sample surface layer by component a of the sample surface layer Serial oxide abundance W _A and the correction diffracted X-ray intensity of the B component of the sample surface layer of A: seeking I _B.com, from a previously obtained calibration curve with the I _B.com, the sample surface layer it is an X-ray diffractometer, wherein calculating means der Rukoto for determining the abundance W _B of the B component.
[0012]
The fourth invention is an X-ray tube 2 for irradiating the surface of a sample being conveyed with X-rays, two or more diffraction X-ray detectors 3A and 3B each having a fixed extraction angle, and the diffraction X A counting circuit 8A for counting the diffracted X-ray intensities of the A and B components of the sample surface layer radiated from the sample surface layer detected by each of the line detectors 3A and 3B, and a fluorescence with a fixed take-off angle X-ray detector 3C, counting circuit unit 8B for counting the fluorescent X-ray intensity detected by the fluorescent X-ray detector 3C, and the diffracted X-ray based on the fluorescent X-ray intensity counted by the counting circuit unit 8B Calculation means 9C for correcting the change in the count values of the diffracted X-ray intensities of the A component and B component due to the change in the distance between the detectors 3A and 3B and the sample, and the sample surface layer corrected by the calculation means 9C abundance of a components of the sample surface layer based on both of the diffracted X-ray intensity I _A.0 and previously obtained calibration curve of a component Calculation means 9D seeking _A, abundance of B component of the diffracted X-ray intensity I _B.0 and previously obtained calibration curve sample surface layer based on both the B component of the sample surface layer, which is corrected by said calculating means 9C have a calculation means 9E seeking further said calculation means (9E) is of the computation means (9C) sample surface layer from the diffraction X-ray intensity I _B.0 of the B component of the corrected sample surface layer a diffracted X-ray intensity of the corrected B component in the abundance W _a of the oxide a and the diffracted X-ray absorption rate by components: seek I _B.com, previously determined and the obtained value of I _B.com calibration from the line, an X-ray diffractometer, wherein calculating means der Rukoto for determining the abundance W _B of the B component of the sample surface layer.
[0014]
Each calibration curve in the first to fourth inventions described above can be obtained in advance using a plurality of samples whose component composition and component concentration are known.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
FIG. 1 (a) shows an example of the X-ray diffraction apparatus of the present invention, and FIG. 1 (b) shows an example of the X-ray tube-X-ray detector storage part of FIG. 1 (a).
In FIG. 1, 1 is an X-ray tube-X-ray detector housing, 2 is an X-ray tube, 3, 3A and 3B are diffracted X-ray detectors, 3C is a fluorescent X-ray detector, and 4 is a high voltage generator. , 5 is a pulse height analyzer, 6 is an X-ray detector high voltage application device, 7 is a measurement angle controller, 8A and 8B are counting circuit units, 9A, 9B, 9C, 9D and 9E are arithmetic means, 10 is a recorder, 11 is a printer, 12 is a display, 13 is a water supply device, 15A, 15B and 15C are solar slits, S is a sample of a metal material such as a steel plate, 2θ _A and 2θ _B are A component and B component of the sample surface to be measured The diffraction angle of the diffracted X-ray, α is the X-ray incident angle on the surface of the sample S, β is the fluorescent X-ray extraction angle with respect to the fluorescent X-ray detector 3C.
[0016]
In the X-ray diffractometer shown in FIG. 1, X-rays from an X-ray tube 2 are irradiated onto the surface of the sample S at an incident angle α, and diffraction corresponding to the A component and B component of the sample surface emitted from the sample S surface. X-rays are detected by X-ray detectors 3A and 3B, respectively, and fluorescent X-rays are detected by fluorescent X-ray detector 3C.
The diffracted X-ray detectors 3A and 3B of the X-ray diffractometer of the present invention are preferably provided with a radix corresponding to the number of components on the sample surface to be measured.
[0017]
In the X-ray diffractometer shown in FIG. 1, the diffracted X-ray detector 3A and the diffracted X-ray detector 3B are arranged at diffraction angles 2θ _A and 2θ _B of diffracted X-rays corresponding to the A component and B component of the sample surface to be measured. Since it is fixed, unlike a normal counter scan method (θ-2θ method), it can be measured quickly in a few seconds.
This is because the composition of the surface of the sample to be measured, such as a continuously flowing metal plate, and the amount of each component are simultaneously online by installing the X-ray diffractometer configured as described above on a continuous production line such as a metal plate. This is because it enables quick and accurate measurement and quick operation management.
[0018]
Further, in the X-ray diffraction apparatus of the present invention, as shown in FIG. 1, it is preferable that a fluorescent X-ray detector 3C fixed at the take-out angle β is installed.
This is because the X-ray fluorescence detector 3C measures the time-dependent change in the characteristic X-ray (fluorescence X-ray) intensity of the matrix simultaneously emitted from the sample surface such as a metal plate. This is because the change over time in the distance between the line detector (3A, 3B) and the surface of the sample such as a metal plate can be corrected, and more accurate measurement becomes possible.
[0019]
Hereinafter, the measurement method and X-ray diffractometer of the metal material surface oxide of the present invention are taken as an example of the measurement of the upper layer Fe ₃ O ₄ and the lower layer FeO 2 in the steel sheet surface oxide layer of the steel plate to be continuously passed. explain.
That is, in the case of a steel plate through which the sample is continuously passed, in the X-ray diffraction apparatus shown in FIG. 1, the surface of the steel plate sample S is irradiated with X-rays from the X-ray tube 2 at an incident angle α. Diffracted X-rays corresponding to FeO and Fe ₃ O ₄ emitted from the surface are detected by X-ray detectors 3A and 3B, respectively.
[0020]
Further, preferably, the fluorescent X-ray emitted from the surface of the sample S is further detected by the fluorescent X-ray detector 3C.
The diffracted X-ray detector 3A and the diffracted X-ray detector 3B are fixed at diffraction angles 2θ _A and 2θ _B of diffracted X-rays corresponding to FeO 2 and Fe ₃ O ₄ to be measured.
Further, when the fluorescent X-ray detector 3C is provided, it is preferably fixed at the extraction angle β.
[0021]
Note that it is preferable that the incident angle α of X-rays be as high as possible to reduce the fluctuation of the diffracted X-ray intensity due to the flickering of the steel sheet.
In the present invention, the diffraction angle 2θ is determined in advance when the diffraction X-ray detector is installed.
FIG. 2 shows a counter scan method (in order to determine the diffraction angle 2θ _B of the diffracted X-ray corresponding to Fe ₃ O ₄ , that is, the mounting angle of the diffracted X-ray detector 3B of the X-ray diffractometer shown in FIG. An example of the result of X-ray diffraction of a steel sheet sample performed by (θ-2θ method) is shown.
[0022]
The steel plate sample used is a sample whose scale is a single composition of magnetite (Fe ₃ O ₄ ).
That is, as shown in FIG. 2, the attachment angle of the diffraction X-ray detector for detecting Fe ₃ O ₄ in the scale of the steel sheet sample is set so that, for example, the diffraction angle 2θ (: 2θ _B ) is 90 °. .
[0023]
Next, the inventors of the present invention made a Fe ₃ O ₄ (511) plane (diffraction angle 2θ) for a plurality of steel sheet samples having a single composition of Fe ₃ O ₄ and a scale amount of 10 to 74 g / m ^2. = 90 °) was measured.
The measurement time of the diffraction X-ray intensity of each sample was 1 s.
Next, the relationship between the amount of scale (Fe ₃ O ₄ ) and the diffraction X-ray intensity was determined.
[0024]
The scale amount of the steel sheet was obtained by weighing the scale peeled off from the steel sheet surface using bromine / methanol.
FIG. 3 shows the relationship between the amount of scale (Fe ₃ O ₄ ) and the diffraction X-ray intensity.
As shown in FIG. 3, although there is some variation, the amount of scale (Fe ₃ O ₄ ): W (Fe ₃ O ₄ ) and the diffraction X-ray intensity of Fe ₃ O ₄ [(511) plane]: I (Fe A calibration curve approximated by the following formula (1) having a good correlation with ₃ O ₄ ) was obtained.
[0025]
W (Fe ₃ O ₄ ) = f (I (Fe ₃ O ₄ )) = 1.38 × 10 ⁻⁸ [I (Fe ₃ O ₄ )] ² −8.21 × 10 ⁻⁵ [I (Fe ₃ O ₄ )] − 1.55 ……… (1)
In order to examine the accuracy of the obtained calibration curve, σ _d obtained by the following equation (2) was calculated.
[0026]
[Expression 1]

[0027]
As a result, 2.0 g / m ² is obtained as σ _d for 10 to 80 g / m ² of Fe ₃ O ₄ adhesion, and the amount of Fe ₃ O ₄ (g / m ² ) can be quantified with sufficient accuracy. I understood.
Next, the diffraction X-ray intensity of the (220) plane of FeO was measured using a steel sheet sample whose scale composition was two components of magnetite (Fe ₃ O ₄ ) and wustite (FeO), and the following (1), ( The relationship between the FeO concentration in the scale and the diffraction X-ray intensity of FeO was obtained by the procedure in 2).
[0028]
(1) Measurement of FeO concentration in scale:
The scale composition ratio was determined by measuring several reflected electron images of the scanning electron microscope (SEM) on the cross section of the steel sheet used, and performing image analysis to remove precipitates and pores in the scale and remove Fe ₃ O ₄ The area ratio of FeO was obtained and multiplied by the respective densities.
[0029]
That is, for example, in the SEM image, when the thickness of Fe ₃ O ₄ is 5 μm, the thickness of FeO is 1 μm, and the observed range is 20 μm, the area of Fe ₃ O ₄ is 1 × 10 ⁻⁶ (cm ² ). Thus, the area of FeO is 0.2 × 10 ⁻⁶ (cm ² ).
If the width of hcm is taken in the direction perpendicular to the cross section, the volumes are 1 × 10 ⁻⁶ h (cm ³ ) and 0.2 × 10 ⁻⁶ h (cm ³ ), respectively.
[0030]
Moreover, since the densities of Fe ₃ O ₄ and FeO are 5.0 g / cm ³ and 5.7 g / cm ³ , respectively, their masses are 5.0 × 10 ⁻⁶ h (g) and 1.14 × 10 ⁻⁶ h (g ).
Therefore, in the case of the above sample, the concentration of FeO with respect to the entire scale is 18.6 mass%.
As a result of performing the above measurement on a plurality of samples, the FeO concentration in the scale of these samples was 0 to 70 mass%.
[0031]
(2) Investigation of the relationship between the FeO concentration in the scale and the diffraction X-ray intensity of FeO:
In the steel plate sample used above, Fe ₃ O ₄ which is a high-order oxide is present on the surface side of the scale (upper layer in the surface oxide layer), and FeO which is a low-order oxide is on the base steel plate side (surface oxide). Present in the lower layer).
As a result, part of the diffracted X-rays from FeO existing in the lower layer is absorbed by the surface Fe ₃ O ₄ .
[0032]
Thus, the diffracted X-ray intensity of Fe ₃ O ₄ of the steel plate samples the [(511) _{plane]: I (Fe 3 O 4} ) and Fe ₃ O ₄ of the steel sheet sample using the calibration curve of the equation (1) Of W: Fe (O ₃ O ₄ ) (g / m ² ), and based on the following formula (3), the diffraction X-ray intensity of the (220) plane of FeO: I (FeO) is determined by Fe ₃ O ₄ . Diffraction X-ray intensity correction value corrected by mass absorption coefficient: μ (m ² / g): I (FeO) _.com was determined.
[0033]
I (FeO). _Com = I (FeO) / exp [−μ · W (Fe ₃ O ₄ )] ……… (3)
In the above formula (3), μ = 67.5 (m ² / g) is shown.
Next, the amount of FeO in the scale: W (FeO) (g / m ² ) and the corrected X-ray diffraction intensity of the (220) plane of absorption corrected FeO: I (FeO). _Com The calibration curve approximated by FIG. 4 and following formula (4) was obtained.
[0034]
W (FeO) = g (I (FeO). _Com ) = 1.57 × 10 ⁻⁴ [I (FeO). _Com ] ² −1.73 × 10 ⁻² [I (FeO). _Com ] (4)
Next, as a result of obtaining the accuracy of the calibration curve using the same calculation formula as the above-mentioned formula (2), σ _d is 3.4 (g / m ² ), and it is found that the lower layer FeO can be analyzed with sufficient accuracy. It was.
Further, FIG. 5 shows the result of obtaining the FeO concentration in the scale from the obtained FeO amount (g / m ² ) and Fe ₃ O ₄ amount (g / m ² ) in comparison with the chemical analysis value.
[0035]
It was found that the FeO concentration can be analyzed at σ _d = 3.1 mass%.
Hereinafter, the method for measuring the surface oxide of a metal material according to the present invention will be described by taking, as an example, the measurement of the upper Fe ₃ O ₄ and the lower FeO 2 in the surface oxide layer of the above steel sheet sample. That is, X-rays from an X-ray tube are irradiated on the steel plate surface, and the diffracted X-ray intensities I (Fe ₃ O ₄ ) and I (FeO) of Fe ₃ O ₄ and FeO emitted from the steel plate surface are measured. .
[0036]
Then, among the oxide layer of the steel sheet sample surface, the presence of Fe ₃ O ₄ that is present in the upper layer W (Fe ₃ O _4), diffraction X-ray intensity I of Fe ₃ O ₄ obtained above (Fe and ₃ O _4), a calibration curve showing the relationship between a previously obtained Fe ₃ O ₄ abundance W (Fe ₃ O ₄₎ and Fe ₃ O ₄ of the diffracted X-ray intensity I (Fe ₃ O ₄₎ wherein It is obtained from the equation (1).
Was then corrected based on both of the diffracted X-ray intensity of the (220) plane of FeO obtained in I abundance (FeO) and _{Fe 3 O 4 W (Fe 3} O 4) and the formula (3) Diffraction X-ray intensity correction value: I (FeO) _.com is obtained.
[0037]
Diffraction X-ray intensity correction value obtained above: I (FeO) _.com and the calibration curve of the above equation (4) can determine the FeO abundance W (FeO) and the FeO concentration in the scale.
As described above, the method for measuring the surface oxide of the metal plate according to the present invention has been described by taking the measurement of Fe ₃ O ₄ and FeO 2 in a steel plate sample as an example. According to the present invention, the X-ray diffractometer illustrated in FIG. By installing in the plate passing (conveying) line, the composition and amount of various oxides on the surface of the metal plate can be simultaneously measured quickly and accurately on-line.
[0038]
That is, when the X-ray diffractometer of the present invention is used, for example, as a measurement device for Fe ₃ O ₄ and FeO 2 in a steel sheet sample, the X-ray diffractometer is composed of the following devices (1) to (4).
(1) X-ray tube 2 that irradiates the surface of a steel sheet with X-rays 2
(2) Diffraction X-ray detectors 3A and 3B with fixed extraction angles
(3) Counting circuit unit 8A
In the counting circuit unit 8A, the diffraction X-ray intensities of Fe ₃ O ₃ and FeO radiated from the steel sheet sample surface layer are counted.
[0039]
(4) Calculation means 9A, 9B
In the calculation means 9A, the diffraction X-ray intensity I (Fe ₃ O ₄ ) of the Fe ₃ O ₄ of the steel sheet sample surface layer counted by the counting circuit unit 8A and the calibration exemplified by the previously obtained equation (1) Based on the line, the abundance W (Fe ₃ O ₄ ) of Fe ₃ O _{4 in} the upper surface layer of the steel sheet sample is determined.
That is, as the calculation means 9A, a calibration curve exemplified by the above-described equation (1) is stored in advance, and the diffracted X-ray intensity I (Fe of Fe ₃ O ₄ of the steel sheet sample surface layer counted by the counting circuit unit 8A. Based on ₃ O ₄ ), it is possible to use a storage / arithmetic device for obtaining the Fe ₃ O ₄ abundance W (Fe ₃ O ₄ ) in the upper surface layer of the steel sheet sample.
[0040]
In the calculating means 9B, <1> W (Fe ₃ O ₄ ) obtained above, <2> the diffraction X-ray intensity I (FeO) of FeO of the steel sheet surface layer counted by the counting circuit section 8A and <3> from the correction equation exemplified by the equation (3), the diffraction X-ray intensity of the oxides FeO corrected by the upper oxide Fe ₃ O ₄ of the diffraction X-ray absorption factor of: I a (FeO) _com. Ask.
Next, in the calculation means 9B, based on the diffraction X-ray intensity obtained above: I (FeO) _.com and the calibration curve exemplified in the above-described equation (4), the steel sheet sample surface layer lower layer The amount of FeO present W (FeO) is obtained.
[0041]
That is, as the calculation means 9B, both the correction equation exemplified by the above-described equation (3) and the calibration curve exemplified by the equation (4) are stored in advance, and the steel sheet sample surface layer counted by the counting circuit unit 8A Based on the diffraction X-ray intensity I (FeO) of FeO and the abundance W (Fe ₃ O ₄ ) of Fe ₃ O _{4 in} the upper surface layer of the steel sheet sample obtained by the arithmetic means 9A, A storage / arithmetic unit for obtaining the abundance W (FeO) can be used.
[0042]
In the present invention, further, the following devices (5) to (7) are provided, whereby diffraction due to a change in the distance between the diffraction X-ray detector (3A, 3B) and the metal sample S over time is provided. The change in the X-ray intensity is corrected, and the oxide can be measured more accurately.
(5) X-ray fluorescence detector 3C
Fluorescent X-ray detector 3C with fixed extraction angle β
(6) Counting circuit section 8B
Counting circuit unit 8B for counting the intensity of fluorescent X-ray detected by the fluorescent X-ray detector 3C
(7) Calculation means 9C
In the calculation means 9C, the diffraction X of each of the A component and the B component due to the change over time of the distance between the diffraction X-ray detector (3A, 3B) and the metal material based on the fluorescent X-ray intensity counted by the counting circuit unit 8B. Correct the change in the line strength count over time.
[0043]
Hereinafter, the correction method based on the fluorescent X-ray intensity will be described by taking the measurement of the oxide on the steel sheet surface as an example.
Assuming that the extraction angle of fluorescent X-rays is β, the distance between the fluorescent X-ray detector and the steel plate changes by d / sin β when the steel plate moves vertically by d with respect to the reference position during measurement.
If the distance between the fluorescent X-ray detector and the center of the measurement circle is L, the fluorescent X-ray intensity ratio is expressed by the following formula (5).
[0044]
I ₁ / I ₀ = L ² / (L + d / sin β) ² (5)
In the above formula (5),
I ₀ : X-ray fluorescence intensity when the steel sheet is at the reference position I ₁ : X-ray fluorescence intensity when the steel sheet is deviated from the reference position by d in the vertical direction.
[0045]
That is, for example, by obtaining the fluorescent X-ray intensity of Fe which is a matrix of a steel plate, d can be obtained by the above formula (5).
Assuming that the detected angle of the diffracted X-ray is δ, L, d, and δ are all known parameters, so the true intensity T ₁ of the diffracted X-ray can be obtained from the following equation (6).
T ₁ = T ₀ · L ² / (L + d / sin δ) ² (6)
In the above formula (6),
T ₀ : Apparent intensity of measured diffraction X-ray T ₁ : Indicates the true intensity of measured diffraction X-ray.
[0046]
The above-described method for calculating the true intensity T ₁ of the diffracted X-ray is applied to the above-described diffracted X-ray intensity: I (Fe ₃ O ₄ ) and diffracted X-ray intensity: I (FeO), and the steel plate is at the reference position. I (Fe ₃ O ₄ ) and I (FeO) for each case, and from the obtained values and the above formulas (1), (3), (4), more accurate Fe ₃ O ₄ , The abundance of FeO can be determined. The five types of storage / calculation devices described above can be a single (one) storage / calculation device.
[0047]
【Example】
Hereinafter, the present invention will be described more specifically based on examples.
In the production line for cold-rolled steel sheets comprising the process sequence of hot rolling equipment → pickling equipment → cold rolling equipment, the X-ray diffraction apparatus shown in FIG. Then, the abundance of Fe ₃ O ₃ and FeO in the scale existing on the steel sheet surface was measured.
[0048]
In the measurement described above, the fluorescent X-ray intensity of Fe, which is a matrix of the steel plate, is measured by the fluorescent X-ray detector 3C shown in FIG. 1, and the diffraction X-ray detector (3A, 3B) and the steel plate sample S are measured. distance variations of the diffracted X-ray intensity by time course of correction, the diffracted X-ray intensity after distance correction: I (Fe ₃ O ₄₎ and the diffracted X-ray intensity: Fe ₃ in the scale on the basis of the I (FeO) O _3. The abundance of FeO was measured.
[0049]
Moreover, in the present Example, the plate | board speed to a pickling facility was controlled based on the obtained measurement result.
The measurement conditions of the X-ray diffractometer were as follows.
Irradiation X-ray: Cr-Kα ray (wavelength: 0.229 nm)
Fe ₃ O ₃ diffraction angle 2θ: 90 °
FeO diffraction angle 2θ: 64 °
As a result, by performing the above-described control, it is possible to reduce the amount of defective pickling of the steel sheet to ½ of the conventional amount.
[0050]
【The invention's effect】
According to the present invention, it is possible to quickly and accurately measure non-destructively the composition and abundance of an oxide present on the surface of a metal material such as a metal plate, and to control the amount of metal surface oxide. It was.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram (a) showing an example of an X-ray diffraction apparatus of the present invention and an explanatory diagram (b) showing an example of an X-ray tube-X-ray detector storage unit.
FIG. 2 is a graph showing an X-ray diffraction result (θ-2θ method) of a steel sheet sample.
FIG. 3 is a graph showing the relationship between the amount of scale (Fe ₃ O ₄ ) and the diffraction X-ray intensity of Fe ₃ O ₄ [(511) plane].
FIG. 4 is a graph showing the relationship between the amount of FeO in the scale and the diffraction X-ray intensity correction value of FeO [(220) plane] corrected for absorption.
FIG. 5 is a graph showing the relationship between the chemical analysis value of the FeO concentration in the scale and the analysis value by the X-ray diffraction method.
[Explanation of symbols]
1 X-ray tube-X-ray detector housing 2 X-ray tube 3, 3A, 3B Diffraction X-ray detector (: X-ray detector)
3C X-ray fluorescence detector 4 High voltage generator 5 Wave height analyzer 6 X-ray detector high voltage application device 7 Measuring angle controller
8A, 8B counting circuit
9A, 9B, 9C, 9D, 9E Calculation means
10 Printer
11 Recorder
12 Day spray
13 Water supply device
15A, 15B, 15C Solar Slit S Sample

Claims (4)

Oxide A emitted from the metal material by irradiating the metal material having oxide A as the upper layer of the surface oxide layer and the metal material having oxide B as the lower layer of the surface oxide layer with characteristic X-rays or monochromatic X-rays Diffracted X-ray intensity I _A and oxide B diffracted X-ray intensity I _B are measured, and from the diffracted X-ray intensity I _{A of} oxide _A and the calibration curve determined in advance, oxide A on the upper surface oxide layer Determination of the amount W _a exists, further oxides diffracted X-ray intensity I _B were corrected by upper diffracted X-ray absorption rate by the oxide a and the abundance W _a of the oxide a oxide B of B calculated diffracted X-ray intensity I _B.com, previously determined from a calibration curve, the surface oxide layer underlying the oxide metal material surface oxidation and obtaining an abundance W _B of B and the I _B.com Measuring method of things. A metal material surface oxide measuring method for measuring a surface oxide of a metal material having an oxide A as an upper layer of a surface oxide layer and an oxide B as a lower layer of a surface oxide layer during transportation of the metal material, Using a X-ray diffractometer with a fixed diffraction angle 2θ and a fluorescent X-ray detector with a fixed extraction angle β with respect to the reference position of the metal material, the metal material is irradiated with characteristic X-rays or monochromatic X-rays, The diffraction X-ray intensity I _A of the oxide A emitted from the metal material and the diffraction X-ray intensity I B of the oxide _B are measured, and the fluorescence X-ray intensity I _FX of the matrix metal emitted from the metal material is measured over time. By measuring the change, the displacement of the metal material from the reference position is obtained, and based on the displacement, the diffracted X-ray intensities I _A and I _B are corrected, and the diffracted X-ray intensity I _A of the obtained oxide A is corrected. and a correction value I _A.0 previously obtained a calibration curve, presence of the upper oxide a Determine the amount W _A, further, the abundance of the diffracted X-ray intensity I _B of the correction value I _B.0 the upper layer of the oxide A by the diffraction X-ray absorption rate between the oxide A oxide B obtained above The diffracted X-ray intensity of oxide B: I _B.0.com is obtained by correcting with W _A, and the existing amount of oxide B in the lower layer W _B is obtained from the I _B.0.com and the calibration curve obtained in advance. A method for measuring a surface oxide of a metal material. An X-ray tube (2) that irradiates the sample surface with X-rays, two or more diffracted X-ray detectors (3A, 3B) each having a fixed extraction angle, and the diffracted X-ray detector (3A) 3B) a counting circuit unit (8A) for counting the diffracted X-ray intensities of the A component and B component of the sample surface layer radiated from the sample surface layer detected in each of the above, and the counting circuit unit (8A) and arithmetic means for obtaining the abundance W _a of the a component of the diffracted X-ray intensity I _a and pre-determined calibration curve sample surface layer based on both the a component of the counted sample surface layer (9A), the counting circuit have a calculation means for calculating the abundance W _B of the B component of the diffracted X-ray intensity I _B and previously obtained sample surface layer based on both of the calibration curve of the B component of the counted sample surface layer (8A) (9B) and, further, the computing means (9B) comprises a diffraction X-ray absorptivity diffracted X-ray intensity I _B of the B component of the sample surface layer by component a of the sample surface layer Diffracted X-ray intensity of the B component of the oxide corrected sample surface layer with the abundance W _A of A: seeking I _B.com, from a previously obtained calibration curve with the I _B.com, the sample surface layer X-ray diffractometer, wherein calculating means der Rukoto for determining the abundance W _B of the B component. An X-ray tube (2) that irradiates the surface of the sample being transported with X-rays, two or more diffracted X-ray detectors (3A, 3B) each having a fixed take-off angle, and diffracted X-ray detection Counting circuit (8A) that counts the diffracted X-ray intensities of the A and B components of the sample surface layer radiated from the sample surface layer detected by each of the detectors (3A and 3B), and the take-off angle is fixed The fluorescent X-ray detector (3C), the counting circuit unit (8B) for counting the fluorescent X-ray intensity detected by the fluorescent X-ray detector (3C), and the counting circuit unit (8B) were counted. Arithmetic means (9C) for correcting changes in the count values of the diffracted X-ray intensities of the A component and B component due to changes in the distance between the diffracted X-ray detector (3A, 3B) and the sample based on the fluorescent X-ray intensity When, a components of the sample surface layer based on both the calculation means (9C) diffracted X-ray intensity of the a component of the corrected sample surface layer with I _A.0 and previously obtained calibration curve And arithmetic means for obtaining the abundance W _A (9D), the sample surface based on both said arithmetic means (9C) diffracted X-ray intensity of the B component of the corrected sample surface layer with I _B.0 and previously obtained calibration curve A calculating means (9E) for determining the abundance of the B component in the layer, and the calculating means (9E) further calculates the diffracted X-ray intensity I of the B component of the sample surface layer corrected by the calculating means (9C); diffracted X-ray intensity of the B component that is corrected by the abundance W _a from _B.0 and the diffracted X-ray absorption rate by the a component of the sample surface layer wherein the oxide a: seek I _B.com, resulting I _B from the value of _.com and previously determined with a calibration curve, X-rays diffractometer it said arithmetic means der Rukoto for determining the abundance W _B of the B component of the sample surface layer.

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