JPH0546495B2 - - Google Patents
Info
- Publication number
- JPH0546495B2 JPH0546495B2 JP15457284A JP15457284A JPH0546495B2 JP H0546495 B2 JPH0546495 B2 JP H0546495B2 JP 15457284 A JP15457284 A JP 15457284A JP 15457284 A JP15457284 A JP 15457284A JP H0546495 B2 JPH0546495 B2 JP H0546495B2
- Authority
- JP
- Japan
- Prior art keywords
- impedance
- electrodes
- coating film
- electrode
- measurement
- 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
Links
- 238000000576 coating method Methods 0.000 claims description 33
- 239000011248 coating agent Substances 0.000 claims description 32
- 238000005259 measurement Methods 0.000 claims description 26
- 238000002847 impedance measurement Methods 0.000 claims description 9
- 239000010953 base metal Substances 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 239000004020 conductor Substances 0.000 claims 1
- 239000003973 paint Substances 0.000 description 27
- 230000006866 deterioration Effects 0.000 description 16
- 238000000034 method Methods 0.000 description 12
- 238000010586 diagram Methods 0.000 description 9
- 230000007423 decrease Effects 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/041—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Measurement Of Resistance Or Impedance (AREA)
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Description
〔発明の利用分野〕
本発明は、防錆・美観等の目的で使用される金
属表面に塗付された塗装膜の劣化を検出、評価す
るために使用される塗膜インピーダンス測定装置
に関する。
〔発明の技術的背景とその問題点〕
まず、従来から行なわれている塗膜劣化の電気
化学的評価方法について説明する。
第5図に表わすように、素地金属1上に塗装し
た評価すべき塗装膜2の上に直接あるいは導電性
の液体ないし導電性のゲルつまり導電性流体3を
介して測定用電極4を接触させる。素地金属1と
測定用電極4間に電流計5を介して交流電源6を
用いて交流電圧を印加する。そのときに印加され
た電圧は素地金属1と測定用電極4に接続された
電圧計7により読取る。
塗装膜2は塗装直後の正常な状態では、電気抵
抗が非常大きく、108Ω・cmあるいはそれ以上の
直流低抗を有する。塗装膜2の電気的等価回路は
塗装膜2が正常な場合には、第6図に示すような
抵抗RfとコンデンサCfとの並列回路で表わされ
る。塗装膜2が劣化してくると、この抵抗Rfが
減少してくるとともに、第6図に示されるような
単純な等価回路から複数の時定数を持つような複
雑なインピーダンスを表わすようになつてくる。
しかしながら、劣化の初期段階では抵抗Rfとコ
ンデンサCfとの並列回路して扱うことが可能であ
る。
塗装膜のインピーダンスZ(jω)は、(1)式から
求められる。
Z(jω)=e(jω)/i(jω) ……(1)
ここで、ωは角周波数、
e(jω)は電圧、
i(jω)は電流を表わす。
また、もう1つの劣化の指標であるtanδは(2)式
で求められる。
tanδ=|Zn|/|Ze| ……(2)
ここで、Znはインピーダンスの虚数部、
Zeはインピーダンスの実数部(インピ
ーダンスが純抵抗と同じ位相の抵抗成分)であ
る。
塗装膜2が劣化してくると、第6図の抵抗Rf
が減少し、同じ交流電圧e(jω)を印加した場合
には電流i(jω)が増加し、インピーダンスZ
(jω)が減少する。同様にして抵抗Rfが減少して
くると、インピーダンスの実数部|Ze|が減少し
tanδが増加する。
このようにして、塗装膜2のインピーダンスあ
るいはtanδを交流インピーダンス法により測定す
ることで、塗装膜2の劣化が検出できる。
塗装膜の劣化前後のインピーダンスの変化を第
7図ならびに第8図に示す。
第7図はインピーダンスの絶対値を周波数(対
数)に対してブロツトしたものであり、一般にボ
ード線図と言われている。劣化していない塗装膜
のインピーダンス曲線aに対して、塗装膜が劣化
してくると、インピーダンスは曲線bのように周
波数の低い側での減少が顕著となる。したがつ
て、インピーダンスの絶対値のみから劣化を検出
する場合には、周波数の低い方で測定する方が有
効である。
第8図はインピーダンスを実数部と虚数部とで
表示したもので、一般にはナイキスト線図と言わ
れる複数表示である。塗装膜2が劣化してくる
と、インピーダンス軌跡dは正常なものの曲線C
と比べて半円が小さくなるとともに、円が変形し
てくる。この形から、塗装膜2の劣化程度が推定
できる。
インピーダンスの測定結果から塗装膜の劣化を
検出する方法は以上の通りであるが、実際の塗装
膜2のインピーダンス測定の際には、素地金属1
から直接電気的なリード線を取出せない場合があ
る。その対処策としてはこの出願人はさきにダブ
ルセル法(2電極法)を提案した。たとえば、特
願昭58−198315(特開昭60−91250号公報)、特願
昭59−55818(特開昭60−20015号公報)等がそれ
である。
この方法は、第9図に示すように2つの測定用
電極4a,4b間に交流電圧を加え、その時の電
圧、電流、周波数から、上述した方法と同様にし
てインピーダンスを測定し、塗装膜2の劣化を検
出する方法である。この場合に測定されるインピ
ーダンスは電極4aと電極4bのインピーダンスの
加算値となる。
しかしながら、この方法を用いてインピーダン
スを測定する場合、塗装膜2のインピーダンスが
非常に大きな塗装系、例えば海洋構造物のように
厚膜系塗膜の測定を行なう場合には、塗装膜表面
のリーク電流が無視できなくなる。塗装膜表面が
汚れている場合、あるいは濡れている場合、ある
いは測定のために電極と塗装膜間に挿入した導電
性の液体ないしはゲルが、電極間に導通を生じさ
せた場合などには、インピーダンス測定結果に誤
差が生じ、本来の塗装膜のインピーダンスが測定
できない場合がある。
第9図において、塗装膜2のインピーダンスは
電圧計7で読取つた電圧e(jω)と電流計5で読
取つた電流i(jω)とから、(1)式により求められ
るが、電流i(jω)は塗装膜2を通つた塗装膜貫
通電流if以外に表面リーク電流isが含まれている
ため、結果してインピーダンスは塗装膜2のイン
ピーダンスよりも小さな値となり、劣化の場合と
同様な判断が下されることになる。表面リークを
少なくする方法としては、測定用電極4aと4bと
の距離を大きくすることが考えられるが、測定装
置が大きくなることあるいは測定物の大きさ、測
定範囲から限定されることが多く、ノイズの面か
らも電極を遠ざけることは好ましくない。
〔発明の目的〕
ここにおいて本発明は、従来装置の難点を克服
し、測定用電極の周囲にガード電極を設け、表面
リーク電流が測定値に影響を与えない正確な測定
が可能な塗膜インピーダンス測定装置を提供する
ことを、その目的とする。
〔発明の概要〕
本発明は、2電極(ダブルセル)による塗膜イ
ンピーダンス測定装置において、
電極間のリーク電流が測定値に影響を与えない
ように、ガード電極を測定電極の周囲に配設した
塗膜インピーダンス測定装置であり、
さらには、ガード電極をアンプを用いて測定電
極と同電位になるようにドライブする塗膜インピ
ーダンス測定装置である。
〔発明の実施例〕
第1図は、本発明の一実施例における回路構成
を表わすブロツク図である。
すべての図面において同一符号は同一もしくは
相当部分を示す。
素地金属1の上に塗られた塗装膜2の上に、直
接あるいは導電性の液体ないしは導電性のゲルも
しくはそれらを含んだ多孔質物質などの導電性物
質3を介して測定電極4aおよび4bを接触させ
る。その測定用電極4aおよび4bは電流計5aお
よび5bを介して交流電源6に接続する。
さらに測定用電極4aおよび4bの周囲にガード
電極8aおよび8bを設け、これらガード電極8a
および8bも塗装膜2に直接あるいは導電性物質
3を介して接触させる。これらガード電極8aお
よび8bは直接交流電源6に接続する。
しかして、測定用電極4aおよび4bあるいはガ
ード電極8aおよび8bの形状は、第2図a,bに
平面図(上の図)、側断面図(下の図)をおのお
の示すように、円形、正方形等被測定物に応じて
どのような形状でも良いが、ガード電極8は測定
電極4aおよび4bの周囲を完全に取巻いている方
が好ましい。
このように構成すると、測定電極4aとガード
電極8aとの間に電流計5aの抵抗による電圧降下
分の電位差が生じるが、測定電極4aとガード電
極8a間の表面リーク抵抗に比べて電流計5aの抵
抗は一般に充分小さいので、この電位差によるガ
ード電極8aから測定電極4aへの流れ込みは、測
定電極iaに比べて充分小さな値となる。
また表面リーク電流isはガード電極8aからの
み流れるので、測定用電極4aに流れる電流iaは
塗装膜2のインピーダンス測定に関与するものだ
けとなる。
測定用電極4b、ガード電極8b、電流計5bに
関しても作用は同じである。
このようにして、塗装膜2の正確なインピーダ
ンス測定が可能となる。
インピーダンス測定用の交流電源6としては、
正弦波以外に、同時に多数の周波数成分を含んだ
インパルスあるいはランダムノイズ等が使用で
き、電流および電圧を伝達関数計に接続すること
で短時間に塗装抵抗Rf、塗装容量Cfないしは第7
図および第8図に示されるようなインピーダンス
軌跡が得られる。
本発明による塗装膜のインピーダンス測定結果
を表1に示す。
[Field of Application of the Invention] The present invention relates to a coating film impedance measuring device used for detecting and evaluating the deterioration of a coating film applied to a metal surface used for purposes such as rust prevention and aesthetics. [Technical background of the invention and its problems] First, a conventional electrochemical evaluation method for paint film deterioration will be explained. As shown in FIG. 5, a measuring electrode 4 is brought into contact with the coating film 2 to be evaluated coated on the base metal 1 either directly or via a conductive liquid or conductive gel, that is, a conductive fluid 3. . An alternating current voltage is applied between the base metal 1 and the measurement electrode 4 using an alternating current power source 6 via an ammeter 5. The voltage applied at that time is read by a voltmeter 7 connected to the base metal 1 and the measuring electrode 4. In the normal state immediately after coating, the coating film 2 has a very high electrical resistance, and has a direct current resistance of 10 8 Ω·cm or more. When the paint film 2 is normal, the electrical equivalent circuit of the paint film 2 is represented by a parallel circuit of a resistor R f and a capacitor C f as shown in FIG. As the paint film 2 deteriorates, this resistance R f decreases, and the simple equivalent circuit shown in Figure 6 begins to represent a complex impedance with multiple time constants. It's coming.
However, at the initial stage of deterioration, it is possible to treat the resistor R f and the capacitor C f as a parallel circuit. The impedance Z (jω) of the coating film is obtained from equation (1). Z(jω)=e(jω)/i(jω)...(1) Here, ω represents the angular frequency, e(jω) represents the voltage, and i(jω) represents the current. Further, tan δ, which is another index of deterioration, is obtained by equation (2). tanδ=|Z n |/|Z e | ...(2) Here, Z n is the imaginary part of the impedance, and Z e is the real part of the impedance (resistance component whose impedance is in the same phase as the pure resistance). As the coating film 2 deteriorates, the resistance R f in Fig. 6
decreases, and when the same AC voltage e(jω) is applied, the current i(jω) increases, and the impedance Z
(jω) decreases. Similarly, as resistance R f decreases, the real part of impedance |Z e | decreases.
tanδ increases. In this way, deterioration of the coating film 2 can be detected by measuring the impedance or tan δ of the coating film 2 by the AC impedance method. Changes in impedance before and after the paint film deteriorates are shown in FIGS. 7 and 8. FIG. 7 shows the absolute value of impedance blotted against frequency (logarithm), and is generally referred to as a Bode diagram. As opposed to the impedance curve a of an undegraded paint film, as the paint film deteriorates, the impedance decreases more markedly on the lower frequency side as shown by curve b. Therefore, when detecting deterioration only from the absolute value of impedance, it is more effective to measure at a lower frequency. FIG. 8 shows the impedance in real and imaginary parts, which is a multiple representation generally called a Nyquist diagram. As the paint film 2 deteriorates, the impedance locus d changes to the normal curve C.
As the semicircle becomes smaller compared to , the circle becomes deformed. From this shape, the degree of deterioration of the coating film 2 can be estimated. The method for detecting the deterioration of the paint film from the impedance measurement results is as described above, but when actually measuring the impedance of the paint film 2, the base metal 1
It may not be possible to take out the electrical lead wires directly from the As a countermeasure to this problem, the applicant previously proposed a double cell method (two-electrode method). For example, Japanese Patent Application No. 58-198315 (Japanese Unexamined Patent Publication No. 60-91250) and Japanese Patent Application No. 59-55818 (Japanese Unexamined Patent Publication No. 60-20015) are examples. In this method, as shown in Figure 9, an AC voltage is applied between two measuring electrodes 4a and 4b , and the impedance is measured from the voltage, current, and frequency in the same manner as the method described above. This is a method for detecting deterioration of the membrane 2. The impedance measured in this case is the sum of the impedances of the electrode 4 a and the electrode 4 b . However, when measuring impedance using this method, when measuring a coating system in which the impedance of the coating film 2 is very high, for example, when measuring a thick coating film such as a marine structure, leakage on the coating film surface may occur. The current can no longer be ignored. If the surface of the paint film is dirty or wet, or if a conductive liquid or gel inserted between the electrode and the paint film creates continuity between the electrodes, the impedance Errors may occur in the measurement results, and the original impedance of the paint film may not be measured. In FIG. 9, the impedance of the coating film 2 is determined by equation (1) from the voltage e(jω) read by the voltmeter 7 and the current i(jω) read by the ammeter 5. ) includes the surface leakage current i s in addition to the paint film penetration current i f passing through the paint film 2, resulting in an impedance smaller than the impedance of the paint film 2, similar to the case of deterioration. A judgment will be made. One possible way to reduce surface leakage is to increase the distance between the measurement electrodes 4a and 4b , but this may increase the size of the measurement device or be limited by the size of the object to be measured or the measurement range. In many cases, it is not preferable to move the electrode away from the noise standpoint. [Object of the Invention] The present invention overcomes the drawbacks of conventional devices, provides a guard electrode around the measurement electrode, and provides coating film impedance that enables accurate measurement without surface leakage current affecting the measured value. Its purpose is to provide a measuring device. [Summary of the Invention] The present invention provides a coating film impedance measurement device using two electrodes (double cell), in which a guard electrode is arranged around the measurement electrode so that leakage current between the electrodes does not affect the measured value. It is a membrane impedance measurement device, and furthermore, it is a coating film impedance measurement device that uses an amplifier to drive the guard electrode to have the same potential as the measurement electrode. [Embodiment of the Invention] FIG. 1 is a block diagram showing a circuit configuration in an embodiment of the present invention. The same reference numerals indicate the same or corresponding parts in all drawings. Measuring electrodes 4 a and 4 are applied directly or via a conductive substance 3 such as a conductive liquid or gel or a porous material containing them onto a coating film 2 applied on a base metal 1 . Bring b into contact. The measurement electrodes 4 a and 4 b are connected to an AC power source 6 via ammeters 5 a and 5 b . Furthermore, guard electrodes 8 a and 8 b are provided around the measurement electrodes 4 a and 4 b , and these guard electrodes 8 a
and 8b are also brought into contact with the coating film 2 directly or via the conductive substance 3. These guard electrodes 8 a and 8 b are directly connected to the AC power source 6 . Therefore, the shape of the measurement electrodes 4 a and 4 b or the guard electrodes 8 a and 8 b is as shown in the plan view (upper figure) and side sectional view (lower figure) in FIGS. 2 a and b, respectively. Although the guard electrode 8 may have any shape depending on the object to be measured, such as circular or square, it is preferable that the guard electrode 8 completely surround the measurement electrodes 4 a and 4 b . With this configuration, a potential difference equal to the voltage drop due to the resistance of the ammeter 5a is generated between the measurement electrode 4a and the guard electrode 8a , but the surface leak resistance between the measurement electrode 4a and the guard electrode 8a is In comparison, the resistance of the ammeter 5a is generally sufficiently small, so that the flow from the guard electrode 8a to the measurement electrode 4a due to this potential difference has a sufficiently small value compared to the measurement electrode ia . Further, since the surface leakage current i s flows only from the guard electrode 8 a , the current i a flowing to the measurement electrode 4 a is only that which is involved in measuring the impedance of the coating film 2. The same effect applies to the measurement electrode 4b , the guard electrode 8b , and the ammeter 5b . In this way, accurate impedance measurement of the coating film 2 becomes possible. As the AC power supply 6 for impedance measurement,
In addition to sine waves, impulses or random noise containing many frequency components simultaneously can be used, and by connecting the current and voltage to a transfer function meter, the coating resistance R f , coating capacitance C f or the seventh
Impedance trajectories as shown in FIG. 8 and FIG. 8 are obtained. Table 1 shows the impedance measurement results of the coating film according to the present invention.
かくして本発明によれば、2電極法(ダブルセ
ル法)による塗膜劣化の検出に使用されるインピ
ーダンス測定装置にガード電極を設けることで、
海洋構造物等に使用される厚膜型塗料のような高
抵抗の塗膜インピーダンスに関しても精度よく測
定できるとともに、測定用電極を近づけることが
可能となり、小型化、耐ノイズ性能が向上し、現
地での測定が精度よく測定できるようになつた。
この結果、塗膜の劣化が早期に検出可能とな
り、寿命の推定、塗換え時期の決定、塗膜の評価
等が短時間に高精度で行なえるようになり、工業
的に益するところ大きい。
Thus, according to the present invention, by providing a guard electrode in an impedance measurement device used for detecting paint film deterioration by the two-electrode method (double cell method),
It is possible to accurately measure the impedance of high-resistance coatings such as those used on marine structures, etc., and it also enables measurement electrodes to be brought closer together, making it more compact and having improved noise resistance. It has become possible to measure with high accuracy. As a result, deterioration of the paint film can be detected early, and life estimation, repainting timing determination, paint film evaluation, etc. can be performed in a short time and with high precision, which is of great industrial benefit.
第1図は本発明の一実施例の回路構成を表わす
ブロツク図、第2図a,bはその電極の形状を示
す平断面図と側断面図、第3図は本発明の他の実
施例の回路構成を表わすブロツク図、第4図a,
bは本発明の別の実施例の側断面図、平断面図、
第5図は従来の塗装膜劣化を電気化学的に評価す
る方法を示す説明図、第6図は塗装膜の劣化を評
価するために用いられる塗装膜の電気的等価回
路、第7図は塗装膜の劣化によるインピーダンス
の周波数依存性の変化を表わす説明図、第8図第
7図を複素平面上で示した説明図、第9図は2電
極法による塗装膜劣化を電気化学的に評価する方
法を表わす説明図である。
1……素地金属、2……塗装膜、3……導電性
物質、4,4a,4b……測定用電極、5,5a,
5b……電流計、6……交流電源、7……電圧計、
8,8a,8b……ガード電極、9……絶縁物、1
0,10a,10b……バツフアアンプ、11,1
1a,11b,12……高入力インピーダンスアン
プ、a,c……正常塗装膜のインピーダンス、そ
の軌跡、b,d……劣化した塗装膜のインピーダ
ンス、その軌跡、Rf……塗膜抵抗、Cf……塗膜容
量、ia……測定電流a、ib……測定電流b、is…
…表面リーク電流、R,Ra,Rb……IV変換抵抗。
FIG. 1 is a block diagram showing the circuit configuration of one embodiment of the present invention, FIGS. 2 a and b are a plan sectional view and a side sectional view showing the shape of the electrode, and FIG. 3 is another embodiment of the present invention. A block diagram showing the circuit configuration of FIG. 4a,
b is a side sectional view and a plan sectional view of another embodiment of the present invention;
Figure 5 is an explanatory diagram showing a conventional method for electrochemically evaluating paint film deterioration, Figure 6 is an electrical equivalent circuit of a paint film used to evaluate paint film deterioration, and Figure 7 is a painting An explanatory diagram showing changes in the frequency dependence of impedance due to film deterioration. Figure 8 is an explanatory diagram showing Figure 7 on a complex plane. Figure 9 is an electrochemical evaluation of paint film deterioration using the two-electrode method. It is an explanatory diagram showing a method. DESCRIPTION OF SYMBOLS 1... Base metal, 2... Paint film, 3... Conductive substance, 4, 4 a , 4 b ... Measuring electrode, 5, 5 a ,
5 b ... Ammeter, 6... AC power supply, 7... Voltmeter,
8, 8 a , 8 b ...Guard electrode, 9...Insulator, 1
0,10 a ,10 b ……Buffer amplifier, 11,1
1 a , 11 b , 12... High input impedance amplifier, a, c... Impedance of normal paint film, its trajectory, b, d... Impedance of deteriorated paint film, its trajectory, R f ... Paint film resistance , C f ... Coating film capacity, i a ... Measurement current a, i b ... Measurement current b, i s ...
...Surface leakage current, R, R a , R b ...IV conversion resistance.
Claims (1)
接あるいは導電性物質を介して設けられた測定用
電極と、 両測定用電極間に接続された交流電源と、 両測定用電極の周囲におのおの直接あるいは導
電物質を介して素地金属表面塗装上に配設され交
流電源の両端に接続れたガード電極と、 両測定用電極間電圧を測定する電圧計と、 両測定用電極を流通する電流を測定する電流計
と、 を備えたことを特徴とする塗膜インピーダンス測
定装置。 2 ガード電極を測定用電極の周囲を取り囲むよ
うにした特許請求の範囲第1項記載の塗膜インピ
ーダンス測定装置。 3 ガード電極をアンプを用いて測定用電極と同
電位になるようにドライブするようにした特許請
求の範囲第1項記載の塗膜インピーダンス測定装
置。 4 電圧計の前段に高入力インプピーダンスアン
プを設けて電圧を検出し、電流計に代えIV(電流
→電圧)変換抵抗を接続しその両端に高入力イン
ピーダンスアンプを備えこのアンプ出力から電流
を導出するようにした特許請求の範囲第1項記載
の塗膜インピーダンス測定装置。[Scope of Claims] 1. Measuring electrodes provided directly or via a conductive substance at two locations on the base metal surface coating, an AC power source connected between both measuring electrodes, and both measuring electrodes. Guard electrodes are placed around the electrodes either directly or via a conductive material on the painted base metal surface and are connected to both ends of the AC power source, a voltmeter that measures the voltage between the electrodes for both measurements, and electrodes for both measurements. A coating film impedance measurement device comprising: an ammeter that measures a current flowing through the impedance. 2. The coating film impedance measuring device according to claim 1, wherein the guard electrode surrounds the measurement electrode. 3. The coating film impedance measuring device according to claim 1, wherein the guard electrode is driven to have the same potential as the measurement electrode using an amplifier. 4 A high input impedance amplifier is installed in front of the voltmeter to detect the voltage, and instead of an ammeter, an IV (current → voltage) conversion resistor is connected, and a high input impedance amplifier is installed at both ends of the resistor, and the current is derived from the output of this amplifier. A coating film impedance measuring device according to claim 1, wherein the coating film impedance measuring device is configured to:
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15457284A JPS6131948A (en) | 1984-07-25 | 1984-07-25 | Instrument for measuring impedance of coated film |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15457284A JPS6131948A (en) | 1984-07-25 | 1984-07-25 | Instrument for measuring impedance of coated film |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6131948A JPS6131948A (en) | 1986-02-14 |
JPH0546495B2 true JPH0546495B2 (en) | 1993-07-14 |
Family
ID=15587158
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP15457284A Granted JPS6131948A (en) | 1984-07-25 | 1984-07-25 | Instrument for measuring impedance of coated film |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6131948A (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6078182A (en) * | 1998-04-21 | 2000-06-20 | Illinois Tool Works Inc | Resistance measuring meter with voltage multiplier |
JP4532357B2 (en) * | 2005-06-15 | 2010-08-25 | 株式会社アタゴ | Concentration measuring device |
JP4748451B2 (en) * | 2006-02-08 | 2011-08-17 | 凸版印刷株式会社 | Hybridization detection method |
JP5625941B2 (en) * | 2011-01-20 | 2014-11-19 | 日産自動車株式会社 | Resistance measuring device and resistance measuring method |
JP2014044102A (en) * | 2012-08-27 | 2014-03-13 | Hioki Ee Corp | Four-terminal resistance measuring device, inspection device, four-terminal resistance measuring method and inspection method |
JP6565979B2 (en) * | 2017-08-04 | 2019-08-28 | マツダ株式会社 | Corrosion resistance test apparatus and corrosion resistance test method for coated metal material |
JP2020118468A (en) * | 2019-01-18 | 2020-08-06 | マツダ株式会社 | Corrosion resistance test device of coated metal material |
JP2023160373A (en) * | 2022-04-22 | 2023-11-02 | 株式会社Screenホールディングス | Impedance measurement apparatus and impedance measurement method |
-
1984
- 1984-07-25 JP JP15457284A patent/JPS6131948A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS6131948A (en) | 1986-02-14 |
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