EP2409143A1 - Détecteur de dommages dus à l'environnement - Google Patents

Détecteur de dommages dus à l'environnement

Info

Publication number
EP2409143A1
EP2409143A1 EP09841991A EP09841991A EP2409143A1 EP 2409143 A1 EP2409143 A1 EP 2409143A1 EP 09841991 A EP09841991 A EP 09841991A EP 09841991 A EP09841991 A EP 09841991A EP 2409143 A1 EP2409143 A1 EP 2409143A1
Authority
EP
European Patent Office
Prior art keywords
magnetic field
sensor
sacrificial material
environment
sensor element
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.)
Withdrawn
Application number
EP09841991A
Other languages
German (de)
English (en)
Other versions
EP2409143A4 (fr
Inventor
David Sean Forsyth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Texas Research International Inc
Original Assignee
Texas Research International Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Texas Research International Inc filed Critical Texas Research International Inc
Publication of EP2409143A1 publication Critical patent/EP2409143A1/fr
Publication of EP2409143A4 publication Critical patent/EP2409143A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/07—Hall effect devices
    • G01R33/072—Constructional adaptation of the sensor to specific applications
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
    • G01N17/04—Corrosion probes
    • G01N17/043—Coupons
    • 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
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
    • G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents

Definitions

  • This invention relates to the general field of sensors and more specifically to sensors for measuring damaging environmental conditions of structures such as corrosion, coatings breakdowns, and fatigue.
  • a major goal in environmental testing has long been to create a sensor that could be utilized in field or service conditions to detect corrosion and adhesion on metal structures of any size before significant degradation has occurred.
  • the immersion of small specimens requires either the destructive sampling of a large structure or the use of witness specimens prepared differently than the actual structure of interest (although the witness specimens and the structure may be prepared at the same time, inherent differences in coating small and large surfaces and inadvertent differences caused by operator error will prevent the witness specimens from being exactly the same as the structure). Additionally, witness specimens will be exposed to slightly different environmental conditions compared to a large structure. Furthermore, the immersion in an electrolyte is not necessarily the exposure condition relevant to the structure being inspected.
  • linear polarization resistance In another prior art application linear polarization resistance (LPR) has been used.
  • LPR linear polarization resistance
  • a potential typically of the order of 10-20 mV
  • linear linear polarization resistance
  • This small potential perturbation is usually applied step-wise, starting below the free corrosion potential and terminating above the free corrosion potential.
  • the polarization resistance is the ratio of the applied potential and the resulting current response. This "resistance” is inversely related to the uniform corrosion rate.
  • Douglas (US Pat. No. 6,843,135) describes an application of using magnetic detectors to monitor corrosion inside of enclosed containers using sacrificial coupons. This approach makes use of spring-loaded coupons that are designed to fail when a specified level of corrosion occurs. A permanent magnet located on the corrosion coupon is used to transmit the failure of the coupon outside of the container. While this approach has potential to provide a contact less monitoring technique, a more continuous monoitoring that would indicate a developing problem is much more desirable.
  • Magnetic Sensors One sensor field of high potential is more modern magnetic sensors. These include, among others, eddy current, Hall effect, and giant magneto resistor sensors These detect changes, or disturbances, in magnetic fields that have been created or modified, and from them derive information on properties such as direction, presence, rotation, angle, or electrical currents. The output signal of these sensors requires some signal processing for translation into the desired parameter. Although magnetic detectors have been considered somewhat more difficult to use, they potentially provide more accurate and reliable data — without physical contact.
  • the test probe is basically a coil of wire through which alternating current is passed. When alternating current is passed through the coil, a magnetic field is generated in and around the coil. When the probe is brought in close proximity to a conductive material, such as aluminum, the probe's changing magnetic field generates current flow in the material. The induced current flows in closed loops in planes perpendicular to the magnetic flux. They are named eddy currents because they are thought to resemble the eddy currents that can be seen swirling in streams.
  • Eddy currents produce their own magnetic fields that interact with the primary magnetic field of the coil.
  • This information includes the electrical conductivity and magnetic permeability of the material, the amount of material cutting through the coils magnetic field, and the condition of the material (i.e. whether it contains cracks or other defects.)
  • the distance that the coil is from the conductive material is called liftoff, and this distance affects the mutual-inductance of the circuits. Liftoff can be used to make measurements of the thickness of nonconductive coatings, such as paint, that hold the probe a certain distance from the surface of the conductive material.
  • the Lorentz force equation describes the force F L experienced by a charged particle with charge q moving with velocity y in a magnetic field B:
  • F L , v, and B are vector quantities, they have both magnitude and direction.
  • the Lorentz force is proportional to the cross product between the vectors representing velocity and magnetic field; it is therefore perpendicular to both of them and, for a positively charged carrier, has the direction of advance of a right-handed screw rotated from the direction of y toward the direction of B.
  • the acceleration caused by the Lorentz force is always perpendicular to the velocity of the charged particle; therefore, in the absence of any other forces, a charge carrier follows a curved path in a magnetic field.
  • the Hall effect is a consequence of the Lorentz force in semiconductor materials.
  • charge carriers When a voltage is applied from one end of a slab of semiconductor material to the other, charge carriers begin to flow. If at the same time a magnetic field is applied perpendicular to the slab, the current carriers are deflected to the side by the Lorentz force. Charge builds up along the side until the resulting electrical field produces a force on the charged particle sufficient to counteract the Lorentz force. This voltage across the slab perpendicular to the applied voltage is called the Hall voltage.
  • Magnetoresistors The simplest Lorentz force devices are magneto resistors that use semiconductors such as InSb and InAs with high room-temperature carrier mobility. If a voltage is applied along the length of a thin slab of semiconductor material, a current will flow and a resistance can be measured. When a magnetic field is applied perpendicular to the slab, the Lorentz force will deflect the charge carriers. If the width of the slab is greater than the length, the charge carriers will cross the slab without a significant number of them collecting along the sides. The effect of the magnetic field is to increase the length of their path and, thus, the resistance. An increase in resistance of several hundred percent is possible in large fields.
  • Magnetoresistors formed from InSb are relatively insensitive in low fields; in high fields, however, they exhibit a resistance that changes approximately as the square of the field. They are sensitive only to that component of the magnetic field perpendicular to the slab and not to whether the field is positive or negative. Their large temperature coefficients of resistivity are caused by the change in mobility of the charge carriers with temperature.
  • the sensors are made with either single resistors or pairs of spaced resistors. The latter are used to measure field gradients and are sometimes combined with external resistors to form a Wheatstone bridge. A permanent magnet is often incorporated in the field gradient sensor to bias the magnetoresistors up to a more sensitive part of their characteristic curve.
  • Hall sensors are often combined with semiconductor elements to create integrated sensors. Adding comparators and output devices to a Hall element, for example, yields unipolar and bipolar digital switches. Adding an amplifier increases the relatively low voltage signals from a Hall device to produce ratiometric linear Hall sensors with an output centered on one-half the supply voltage. Power usage can even be reduced to extremely low levels by using a low duty cycle.
  • Giant Magnetoresistive (GMR) Devices Large magnetic field dependent changes in resistance are possible in thin film ferromagnet/nonmagnetic metallic multilayers. Changes in resistance with magnetic field of up to 70% have been seen. Compared to the small percent change in resistance observed in anisotropic magnetoresistance, this phenomenon was truly giant magnetoresistance.
  • the resistance of two thin ferromagnetic layers separated by a thin nonmagnetic conducting layer can be altered by changing the moments of the ferromagnetic layers from parallel to antiparallel, or parallel but in the opposite direction.
  • GMR materials for magnetic field sensors are sometimes used in Wheatstone bridge configurations, although simple GMR resistors and GMR half bridges can also be fabricated.
  • a sensitive bridge can be made from four photolithographically patterned GMR resistors, two of which are active elements. These resistors can be as narrow as 2 ⁇ m, allowing a serpentine 10 k resistor to be patterned in an area as small as 100 ⁇ m 2 . The vary narrow width also makes the resistors sensitive only to the magnetic field component along their long dimension. Small magnetic shields are plated over two of the four equal resistors in a Wheatstone bridge, protecting them from the applied field and allowing them to act as reference resistors. Since they are fabricated from the same material, they have the same temperature coefficient as the active resistors. The two remaining GMR resistors are both exposed to the external field. The bridge output is therefore twice the output from a bridge with only one active resistor. The bridge output for a 10% change in these resistors is ⁇ 5% of the voltage applied to the bridge.
  • GMR materials are sputtered onto wafers and can therefore be directly integrated with semiconductor processes.
  • the small sensing elements fit well with the other semiconductor structures and are applied after most of the semiconductor fabrication operations are complete. Because of the topography introduced by the many layers of polysilicon, metal, and oxides over the transistors, areas must be reserved with no underlying transistors or connections. These areas will have the GMR resistors.
  • the GMR materials are actually deposited over the entire wafer, but the etched sensor elements remain only on these reserved, smooth areas on the wafers.
  • a 2-wire sensor can be designed that has two current levels — low when the field is below a threshold and high when the field is above the threshold.
  • Onboard sensor electronics can increase signal levels to significant voltages with the least pickup of interference. It is always best to amplify low-level signals close to where they are generated. Converting analog signals to digital (switched) outputs within the sensor is another way to minimize electronic noise.
  • the use of comparators and digital outputs makes the nonlinearity in the output of sandwich GMR materials of less concern. Even the hysteresis in such materials can be useful, since some hysteresis is usually built into comparators to avoid multiple triggering of the output due to noise.
  • GMR materials have been successfully integrated with both BiCMOS and bipolar semiconductor underlayers.
  • the wafers are processed with all but the final layer of connections complete.
  • GMR material is deposited on the surface and patterned.
  • the next step is the application of a passivation layer through which windows are cut to permit contact to both the upper metal layer in the semiconductor wafer and to the GMR resistors.
  • the final layer of metal is then deposited and patterned to interconnect the GMR sensor elements and to connect them to the semiconductor underlayers. This layer also forms the pads to which wires will be bonded during packaging.
  • a final passivation layer is deposited, magnetic shields and flux concentrators are plated and patterned, and windows are etched through to the pads.
  • One aspect of the invention is a sensor apparatus for measuring environmental degradation in the environment of a structure including at least: a first magnetic field sensor element with associated electronics mounted in a fixed position in a sensor housing, the sensor housing mounted in close proximity to the structure; a first sacrificial material coupon mounted in a fixed position in the immediate vicinity of the magnetic field sensor element, the first sacrificial material coupon being chosen to represent the material of the structure and being mounted so as to be exposed to the environment of the structure; and a system for recording magnetic field or magnetic field changes as measured by the first magnetic field sensor element.
  • Another aspect of the invention is a sensor apparatus for measuring environmental degradation in the environment of a structure including at least: a first magnetic field sensor element with associated electronics mounted in a fixed position in a sensor housing, the sensor housing mounted in close proximity to the structure; a first sacrificial material coupon mounted in a fixed position in the immediate vicinity of the magnetic field sensor element, the first sacrificial material coupon being chosen to represent the material of the structure and being mounted so as to be exposed to the environment of the structure; a second sacrificial material coupon with associated electronics mounted in a fixed position in the immediate vicinity of a second magnetic field sensor element, the second material coupon mounted so as to not be exposed to the environment of the structure; wherein the second sacrificial material coupon is of the same material of the first sacrificial material coupon; and a system for recording differences in magnetic field strengths detected between the first and the second magnetic field sensor elements.
  • Another aspect of the invention is a sensor apparatus for measuring environmental degradation in the environment of a structure including at least: a first magnetic field sensor element with associated electronics mounted in a fixed position in a sensor housing; a first sacrificial material coupon mounted in a fixed position in the immediate vicinity of the magnetic field sensor element, the first sacrificial material coupon being chosen to represent the material of the structure and being mounted so as to be exposed to the environment of the structure; and a system for recording magnetic field or magnetic field changes as measured by the first magnetic field sensor element further including rigidly fixing the first sacrificial material coupon directly to the structure.
  • Another aspect of the invention is a method for measuring environmental degradation in the environment of a structure comprising the steps of: mounting a first magnetic field sensor element with associated electronics in a fixed position in a sensor housing, the sensor housing mounted in close proximity to the structure; mounting a first sacrificial material coupon in a fixed position in the immediate vicinity of the magnetic field sensor element, wherein the first sacrificial material coupon is chosen to represent the material of the structure and is mounted so as to be exposed to the environment of the structure; and recording magnetic field or magnetic field changes as measured by the first magnetic field sensor element and using those recordings to measure the environmental degradation in the environment of the structure.
  • Another aspect of the invention is a method for measuring environmental degradation in the environment of a structure comprising the steps of: mounting a first magnetic field sensor element with associated electronics in a fixed position in a sensor housing, the sensor housing mounted in close proximity to the structure; mounting a first sacrificial material coupon in a fixed position in the immediate vicinity of the magnetic field sensor element, wherein the first sacrificial material coupon is chosen to represent the material of the structure and is mounted so as to be exposed to the environment of the structure; mounting a second sacrificial material coupon in a fixed position in the immediate vicinity of a second magnetic field sensor element with associated electronics, the second material coupon mounted so as to not be exposed to the environment of the structure; wherein the second sacrificial material coupon is of the same material of the first sacrificial material coupon; and recording differences in magnetic field strengths detected between the first and the second magnetic field sensor elements, and using those recordings to measure the environmental degradation in the environment of the structure.
  • Another aspect of the invention is a method for measuring environmental degradation in the environment of a structure comprising the steps of: mounting a first magnetic field sensor element with associated electronics in a fixed position in a sensor housing, the sensor housing mounted in close proximity to the structure; mounting a first sacrificial material coupon in a fixed position in the immediate vicinity of the magnetic field sensor element, wherein the first sacrificial material coupon is chosen to represent the material of the structure and is mounted so as to be exposed to the environment of the structure; further including rigidly fixing the first sacrificial material coupon directly to the structure and; recording magnetic field or magnetic field changes as measured by the first magnetic field sensor element and using those recordings to measure the environmental degradation in the environment of the structure.
  • Figure 1 is a side and top view of one aspect of the invention.
  • Figure 2 is a side and top view of one aspect of the invention.
  • Figure 3 is a side and top view of one aspect of the invention.
  • FIG. 100 represented generally by the numeral 100 illustrates an aspect of the instant invention.
  • a magnetic sensor element 130 is mounted in a fixed position in a sensor housing 120.
  • the sensor housing 120 is mounted on or in close proximity to the structure 140 that is being monitored.
  • the sensor housing could be made of any number of non-magnetic materials, such as aluminum, or a plastic material.
  • Mounted in close proximity or in direct contact to sensor element 130 is a sacrificial material coupon 110.
  • Sacrificial material coupon 110 is chosen to match the material of structure 140. As shown in Figure 1 a significant portion of sacrificial material coupon 110 is exposed to the environment surrounding structure 140.
  • Element 150 is a spacer or gasket to aid in mounting sacrificial material coupon 110 and is not critical to the instant invention.
  • Figure 1 indicates a sensor housing 120 as being made up of separate parts but could also be an integral single piece surrounding sensor housing 120 and sacrificial material coupon 110. Not shown in the Figure 1 is the electronics associated with sensor element 130 that would capture and record magnetic field strength or magnetic fluxes over time. The data collected could be stored integrally in memory in sensor housing 120, or transmitted by wiring or wirelessly to remote environmental monitoring equipment.
  • Magnetic sensor 130 could for example be a AD22151G linear output magnetic field transducer (Hall Effect) manufactured by Analog Devices of Norwood, Massachusetts. Alternately a giant magnetoresistance detector such as model AAH-004-00 magnetometer, manufactured by NVE Corporation of Eden Prairie, Minnesota. These sensors, as well as select eddy current sensors are suited to this application.
  • FIG 2 represented generally by the numeral 200, illustrates a further application of the instant invention.
  • a first magnetic sensor element 230 is mounted in a fixed position in a sensor housing 220.
  • the sensor housing 220 is mounted on or in close proximity to the structure 240 that is being monitored.
  • the sensor housing could be made of any number of nonmagnetic materials, such as aluminum, or a plastic material.
  • Mounted in close proximity or in direct contact to sensor element 230 is a sacrificial material coupon 210. Sacrificial material coupon 210 is chosen to match the material of structure 240. As shown in Figure 2 a significant portion of sacrificial material coupon 210 is exposed to the environment surrounding structure 240.
  • a second magnetic sensor element 235 is mounted in a fixed position in a sensor housing 220.
  • a second sacrificial material coupon 225 is mounted in close proximity or in contact with magnetic sensor element 235.
  • Sacrificial material coupon 225 is sealed from exposure to the environment by being sealed inside sensor housing 220.
  • magnetic sensor elements 230 and 235 would be identical in nature, as would the material of sacrificial material coupons 210 and 225.
  • Magnetic sensor elements 210 and 235 are in communication, either wired or wirelessly with a differential measurement system 250 to measure and record the differences in magnetic field or magnetic flux measurements. This aspect of the invention allows environmental degradation to be measured as the difference between two relatively identical sacrificial material coupons, one being exposed to the environment and the other not exposed. It should be noted that although the two sensor housings are shown as separate, in practice this could be an integral sensor housing.
  • Figure 3 represented generally by the numeral 300, represents another embodiment of the instant invention.
  • the sensor housing 320 containing the fixed magnetic sensor element 330 is mounted onto structure 340.
  • Sacrificial material coupon 310 is placed in close proximity to magnetic sensor element 330 but in addition is rigidly fixed to structure 340 with mounting elements 350.
  • Other means, such as a load frame (not shown) could be used couple the sacrificial material coupon to the structure.
  • the electronics associated with sensor element 330 that would capture and record magnetic field strength or magnetic fluxes over time. The data collected could be stored integrally in memory in sensor housing 320, or transmitted by wiring or wirelessly to remote environmental monitoring equipment.
  • Processing of the data from these various aspects of the invention is used to monitor corrosion.
  • Field strength as measured by the sensor is proportional to current, which is proportional to actual damage.
  • the corrosion magnetic field contains spatial and temporal information that correlate with the distribution, magnitude, and time course of currents associated with electrochemical corrosion.
  • the magnetic activity of a corroding sample can be used for non- destructive and real-time quantification of electrochemical corrosion activity of non-ferromagnetic metals.

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  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Immunology (AREA)
  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Ecology (AREA)
  • Environmental Sciences (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)

Abstract

L'appareil de détection ci-décrit permettant de mesurer la dégradation d'une structure due à l'environnement utilise des coupons de matériaux sacrifiés exposés, montés au voisinage immédiat d'éléments de détection magnétiques dans l'environnement de la structure sous surveillance.
EP09841991.4A 2009-03-18 2009-03-18 Détecteur de dommages dus à l'environnement Withdrawn EP2409143A4 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2009/001690 WO2010107413A1 (fr) 2009-03-18 2009-03-18 Détecteur de dommages dus à l'environnement

Publications (2)

Publication Number Publication Date
EP2409143A1 true EP2409143A1 (fr) 2012-01-25
EP2409143A4 EP2409143A4 (fr) 2017-11-08

Family

ID=42739885

Family Applications (1)

Application Number Title Priority Date Filing Date
EP09841991.4A Withdrawn EP2409143A4 (fr) 2009-03-18 2009-03-18 Détecteur de dommages dus à l'environnement

Country Status (3)

Country Link
EP (1) EP2409143A4 (fr)
CA (1) CA2754181C (fr)
WO (1) WO2010107413A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11598714B1 (en) * 2021-06-17 2023-03-07 Matergenics, Inc. Alternating current interference corrosion detector

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004523767A (ja) * 2001-03-16 2004-08-05 シーメンス　アクチエンゲゼルシヤフト 炭化物含有合金又は表面近傍が硫化された合金の非破壊検査方法およびガスタービン翼の製造方法
WO2004003255A2 (fr) * 2002-06-28 2004-01-08 Vista Engineering Technologies, L.L.C. Procede et appareil de surveillance a distance de la corrosion a l'aide d'echantillons
GB0226249D0 (en) 2002-11-11 2002-12-18 Clearspeed Technology Ltd Traffic handling system
JP2007192803A (ja) * 2005-12-19 2007-08-02 Ishikawajima Harima Heavy Ind Co Ltd 腐食評価装置及び腐食評価方法
JP4007386B2 (ja) * 2006-01-12 2007-11-14 Ｔｄｋ株式会社 渦電流プローブ
JP2008175638A (ja) * 2007-01-17 2008-07-31 Toshiba Corp 構造材の欠陥検出装置及び方法
US8085165B2 (en) * 2007-02-09 2011-12-27 Luna Innovations Incorporated Wireless corrosion sensor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2010107413A1 *

Also Published As

Publication number Publication date
CA2754181C (fr) 2016-08-02
EP2409143A4 (fr) 2017-11-08
CA2754181A1 (fr) 2010-09-23
WO2010107413A1 (fr) 2010-09-23

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