산업구조물의 다양화와 구조물의 노후화에 의하여 부식 및 방식에 대한 인식이 점차 증가하고 있다. 구조물의 이용에 대하여 어떻게 하면 안전하게, 장시간 사용할 수 있는 가에 대한 연구가 활발히 친행 중이다. 본 연구에서는 구조물의 부식속도를 모니터링 하는 박막센서를 제작하고자 하였다. 여러 가지 방법의 부식속도를 측정하기위한 실험은 다음과 같은 목적에 이용된다. 어떤 특정한 용도에 가장 적합한 금속 또는 합금 선정, 장비나 기구의 사용수명 결정, 신개발합금 또는 그 제조법 평가, 환경의 조절 및 변화에 대한평가, 부식을 방지하기 위한 가장 경제적인 방법결정 및 부식기구 연구 등의 목적이 있다. 따라서 정확한 부식속도를 측정하는 것은 매우 중요한 일이 된다. 기존에 구조물의 부식속도를 평가하는 방법은 작은 시편의 무게손실(weight ...
산업구조물의 다양화와 구조물의 노후화에 의하여 부식 및 방식에 대한 인식이 점차 증가하고 있다. 구조물의 이용에 대하여 어떻게 하면 안전하게, 장시간 사용할 수 있는 가에 대한 연구가 활발히 친행 중이다. 본 연구에서는 구조물의 부식속도를 모니터링 하는 박막센서를 제작하고자 하였다. 여러 가지 방법의 부식속도를 측정하기위한 실험은 다음과 같은 목적에 이용된다. 어떤 특정한 용도에 가장 적합한 금속 또는 합금 선정, 장비나 기구의 사용수명 결정, 신개발합금 또는 그 제조법 평가, 환경의 조절 및 변화에 대한평가, 부식을 방지하기 위한 가장 경제적인 방법결정 및 부식기구 연구 등의 목적이 있다. 따라서 정확한 부식속도를 측정하는 것은 매우 중요한 일이 된다. 기존에 구조물의 부식속도를 평가하는 방법은 작은 시편의 무게손실(weight loss)에 의한 균일 부식속도 측정이 있다. 이 방법은 일정한 시간이 흐른 후 시편의 무게감량으로 그 결과를 얻으므로 얻어지는 정보는 부식이 진행후의 결과만 보여준다. 향후 부식량과 부식속도에 대한정보는 얻기 힘들다. 또한 X선 탐상법, 자기탐상법등과 같은 비파괴적인 방법 또한 현재의 결과만을 보여줄 뿐이다. 여러 가지 부식속도 측정 방법 중 전기저항법을 이용하며 부식속도 측정하는 센서를 개발하고 센서의 민감도를 향상시키기 위하여 측정부의 두께를 감소시켜 박막으로 제작하여 부식환경 변화에 대한 민감한 센서를 개발 하고자 하였다. 박막은 기본적으로 벌크와 물성이 다르다. 따라서 박막을 이용하여 벌크의 부식속도를 나타내고자할 때는 박막의 기본적인 물성파악이 필수적으로 선행되어야 한다. 따라서 다양한 전기화학적 실험을 통하여 벌크와 박막의 물성을 확인하였다. 부식속도 측정용 박막저항센서의 국부부식 민감도를 향상시키기 위하여 패턴형태를 바꾸었다. single line의 센서에서 multiple line의 센서로 측정부이 패턴을 바꾸었다. 또한 multiple line의 부식속도 측정용 박막저항센서를 제작하여 기판물질에 따른 특성변화를 살펴보고 여러 가지 환경에 적용하였을 경우의 센서 응답성을 확인하였다. multiple line으로 패턴을 변경하였을 때 국부부식의 민감성을 향상됨을 보여 주었고, 다양한 부식환경에 노출되었을 경우 부식성에 따라서 박막센서의 응답이 변함을 확인하였다. 또한 음극전기방식의 부식속도가 낮은 환경에 적용하였을 때 방식환경 변화에도 민감한 반응을 보임을 확인하였다.
산업구조물의 다양화와 구조물의 노후화에 의하여 부식 및 방식에 대한 인식이 점차 증가하고 있다. 구조물의 이용에 대하여 어떻게 하면 안전하게, 장시간 사용할 수 있는 가에 대한 연구가 활발히 친행 중이다. 본 연구에서는 구조물의 부식속도를 모니터링 하는 박막센서를 제작하고자 하였다. 여러 가지 방법의 부식속도를 측정하기위한 실험은 다음과 같은 목적에 이용된다. 어떤 특정한 용도에 가장 적합한 금속 또는 합금 선정, 장비나 기구의 사용수명 결정, 신개발합금 또는 그 제조법 평가, 환경의 조절 및 변화에 대한평가, 부식을 방지하기 위한 가장 경제적인 방법결정 및 부식기구 연구 등의 목적이 있다. 따라서 정확한 부식속도를 측정하는 것은 매우 중요한 일이 된다. 기존에 구조물의 부식속도를 평가하는 방법은 작은 시편의 무게손실(weight loss)에 의한 균일 부식속도 측정이 있다. 이 방법은 일정한 시간이 흐른 후 시편의 무게감량으로 그 결과를 얻으므로 얻어지는 정보는 부식이 진행후의 결과만 보여준다. 향후 부식량과 부식속도에 대한정보는 얻기 힘들다. 또한 X선 탐상법, 자기탐상법등과 같은 비파괴적인 방법 또한 현재의 결과만을 보여줄 뿐이다. 여러 가지 부식속도 측정 방법 중 전기저항법을 이용하며 부식속도 측정하는 센서를 개발하고 센서의 민감도를 향상시키기 위하여 측정부의 두께를 감소시켜 박막으로 제작하여 부식환경 변화에 대한 민감한 센서를 개발 하고자 하였다. 박막은 기본적으로 벌크와 물성이 다르다. 따라서 박막을 이용하여 벌크의 부식속도를 나타내고자할 때는 박막의 기본적인 물성파악이 필수적으로 선행되어야 한다. 따라서 다양한 전기화학적 실험을 통하여 벌크와 박막의 물성을 확인하였다. 부식속도 측정용 박막저항센서의 국부부식 민감도를 향상시키기 위하여 패턴형태를 바꾸었다. single line의 센서에서 multiple line의 센서로 측정부이 패턴을 바꾸었다. 또한 multiple line의 부식속도 측정용 박막저항센서를 제작하여 기판물질에 따른 특성변화를 살펴보고 여러 가지 환경에 적용하였을 경우의 센서 응답성을 확인하였다. multiple line으로 패턴을 변경하였을 때 국부부식의 민감성을 향상됨을 보여 주었고, 다양한 부식환경에 노출되었을 경우 부식성에 따라서 박막센서의 응답이 변함을 확인하였다. 또한 음극전기방식의 부식속도가 낮은 환경에 적용하였을 때 방식환경 변화에도 민감한 반응을 보임을 확인하였다.
There has been growing interest in corrosion monitoring since it is crucial in aging systems in that it enables one to evaluate corrosion risks and predict the service life of construction materials. Corrosion monitoring also plays an important role in paradigm shift regarding maintenance of aging s...
There has been growing interest in corrosion monitoring since it is crucial in aging systems in that it enables one to evaluate corrosion risks and predict the service life of construction materials. Corrosion monitoring also plays an important role in paradigm shift regarding maintenance of aging systems_ One can rely on a new preventive and predictive maintenance approaches, rather than more costly and old-fashioned corrective maintenance practices, provided that reliable corrosion monitoring methods are available. Both qualitative (likeliness of corrosion) and quantitative (corrosion rate) information are requisite for innovative maintenance of aging systems. Corrosion damage is generally reported as metal loss or penetration as a function of time. In many situations, the service conditions involve unknown parameters and/or unexpected conditions where corrosion rates are not constant with time. In cases when any corrosion mitigation measures such as use of inhibitors and cathodicprotection are incorporated, corrosion monitoring for verification control is important. Different monitoring techniques are available in industrial processes but the need for more reliable, sensitive and accurate corrosion monitoring systems is still in great demand. Various monitoring techniques, such as weight loss coupon, thin film activation, linear polarization (LP), electrical resistance (ER), electrochemical noise and impedance spectroscopy, have been proposed. Among these, three techniques of weight loss coupon, LP and ER have been extensively used for field application at present time. These methods, however, have their limitations which are outlined below. In the weight loss coupon method a coupon is exposed to the corrosive medium and periodically withdrawn to measure its loss in weight. This is the most widely utilized monitoring method due to its simplicity and straightforwardness in data interpretation. This method, however, is generally a long, tedious process which requires a considerable time span. It often does not produce satisfactory results especially when the corrosion rate changes with time. In the ER method, one measures the increase in electric resistance of a probe as its cross-sectional area is reduced by corrosion. This method provides the means to automate the corrosion rate and absolute measure of metal loss. A resistance conductor probe is made of materials of interest and has the shape of wire or strip or tube. One should understand the trade off feature between the probe life and sensitivity. The sensitivity of the ER probe is decided by the thickness of the element: the thicker the probe element the slower the response time. Like weight loss coupon, the sensitivity of ER prove is so low that low values of corrosion rates cannot measured over a short period of time. Denzine and Reading reported that it will take more than 60~70 hours to register a corrosion rate change of 1 mpy with conventional ER probes. Recently, new method has been developed to enhance the resolution of ER method. In this method one measures magnetic inductive resistance change of the probe insteadof electrical resistance change. This method could sensitively detect dimension change of the probe and significantly reduce the fluctuation of the reading from temperature change of the probe. This method could be applied to soft ferromagnetic materials like carbon steel. In other attempt, thin metal film was employed in ER probes. As the thickness of the probe could be controlled at extremely low level, the sensitivity of the sensor could be manipulated at the desired range. It has been reported that these thin film probes are applicable to an atmospheric corrosion monitoring where the corrosion rate is low and usually uniform. This thin film probe could be useful in the application where corrosion is inhibited by protection method, for example, cathodically protected structure. When the protection system is properly working, the corrosion rate of the structure is practically zero and the life of the sensor is unlimited. The desired property of the corrosion monitoring system for protected structure lies in its ability to detect the interruption of the protection system as soon as possible. We could expect many applications of the thin film type prove, however few papers have been published on the application of the thin film probes. On this subject there are one important thing to be done before wide application of the thin film ER sensor. Usually sputtered thin film and target materials have different characteristics. One should know the effect of this difference on the monitoring capability of the sensor. Another limitation of ER probe method lies in inaccuracy to local corrosion. Severe pitting corrosion could occur without significant metal loss and resistance change. Sometimes localized thinning puts a high resistance giving inflated corrosion rate reading. This study presents the characteristics of the thin film ER probe in various conditions. thin metal film made by sputtering of commercial grade mild steel. We investigated the relation between film deposition condition and the corrosion behavior of the thin film in various environments.Another goal of this study was improvement of sensitivity to localized corrosion. As mentioned above non-uniform corrosion could influence the response of the ER probe severely. We improved the response of the sensor to localized corrosion using new design of multiple narrow lined elements. This method utilizes averaging effect of irregular response of the individual single line during non-uniform corrosion. The response of the improved sensor was compared with commercial bulk probe in three solutions of different corrosiveness. We also wish to report herein a result from application of thin film probe for cathodic protection monitoring which is one of the promising applications of the sensor.
There has been growing interest in corrosion monitoring since it is crucial in aging systems in that it enables one to evaluate corrosion risks and predict the service life of construction materials. Corrosion monitoring also plays an important role in paradigm shift regarding maintenance of aging systems_ One can rely on a new preventive and predictive maintenance approaches, rather than more costly and old-fashioned corrective maintenance practices, provided that reliable corrosion monitoring methods are available. Both qualitative (likeliness of corrosion) and quantitative (corrosion rate) information are requisite for innovative maintenance of aging systems. Corrosion damage is generally reported as metal loss or penetration as a function of time. In many situations, the service conditions involve unknown parameters and/or unexpected conditions where corrosion rates are not constant with time. In cases when any corrosion mitigation measures such as use of inhibitors and cathodicprotection are incorporated, corrosion monitoring for verification control is important. Different monitoring techniques are available in industrial processes but the need for more reliable, sensitive and accurate corrosion monitoring systems is still in great demand. Various monitoring techniques, such as weight loss coupon, thin film activation, linear polarization (LP), electrical resistance (ER), electrochemical noise and impedance spectroscopy, have been proposed. Among these, three techniques of weight loss coupon, LP and ER have been extensively used for field application at present time. These methods, however, have their limitations which are outlined below. In the weight loss coupon method a coupon is exposed to the corrosive medium and periodically withdrawn to measure its loss in weight. This is the most widely utilized monitoring method due to its simplicity and straightforwardness in data interpretation. This method, however, is generally a long, tedious process which requires a considerable time span. It often does not produce satisfactory results especially when the corrosion rate changes with time. In the ER method, one measures the increase in electric resistance of a probe as its cross-sectional area is reduced by corrosion. This method provides the means to automate the corrosion rate and absolute measure of metal loss. A resistance conductor probe is made of materials of interest and has the shape of wire or strip or tube. One should understand the trade off feature between the probe life and sensitivity. The sensitivity of the ER probe is decided by the thickness of the element: the thicker the probe element the slower the response time. Like weight loss coupon, the sensitivity of ER prove is so low that low values of corrosion rates cannot measured over a short period of time. Denzine and Reading reported that it will take more than 60~70 hours to register a corrosion rate change of 1 mpy with conventional ER probes. Recently, new method has been developed to enhance the resolution of ER method. In this method one measures magnetic inductive resistance change of the probe insteadof electrical resistance change. This method could sensitively detect dimension change of the probe and significantly reduce the fluctuation of the reading from temperature change of the probe. This method could be applied to soft ferromagnetic materials like carbon steel. In other attempt, thin metal film was employed in ER probes. As the thickness of the probe could be controlled at extremely low level, the sensitivity of the sensor could be manipulated at the desired range. It has been reported that these thin film probes are applicable to an atmospheric corrosion monitoring where the corrosion rate is low and usually uniform. This thin film probe could be useful in the application where corrosion is inhibited by protection method, for example, cathodically protected structure. When the protection system is properly working, the corrosion rate of the structure is practically zero and the life of the sensor is unlimited. The desired property of the corrosion monitoring system for protected structure lies in its ability to detect the interruption of the protection system as soon as possible. We could expect many applications of the thin film type prove, however few papers have been published on the application of the thin film probes. On this subject there are one important thing to be done before wide application of the thin film ER sensor. Usually sputtered thin film and target materials have different characteristics. One should know the effect of this difference on the monitoring capability of the sensor. Another limitation of ER probe method lies in inaccuracy to local corrosion. Severe pitting corrosion could occur without significant metal loss and resistance change. Sometimes localized thinning puts a high resistance giving inflated corrosion rate reading. This study presents the characteristics of the thin film ER probe in various conditions. thin metal film made by sputtering of commercial grade mild steel. We investigated the relation between film deposition condition and the corrosion behavior of the thin film in various environments.Another goal of this study was improvement of sensitivity to localized corrosion. As mentioned above non-uniform corrosion could influence the response of the ER probe severely. We improved the response of the sensor to localized corrosion using new design of multiple narrow lined elements. This method utilizes averaging effect of irregular response of the individual single line during non-uniform corrosion. The response of the improved sensor was compared with commercial bulk probe in three solutions of different corrosiveness. We also wish to report herein a result from application of thin film probe for cathodic protection monitoring which is one of the promising applications of the sensor.
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