Measuring and testing – Testing of material
Reexamination Certificate
2000-08-08
2001-07-31
Noori, Max (Department: 2855)
Measuring and testing
Testing of material
Reexamination Certificate
active
06267017
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to non-destructive testing of materials for their fatigue status, and more particularly to a transducer cell array for use with electrochemical and electromechanical impedance methods for such testing.
BACKGROUND OF THE INVENTION
Fatigue damage of various materials has been a topic of considerable economic importance and one to which a significant amount of scientific and engineering effort has been devoted over the latter half of this century. Methods for non-destructive testing are of particular interest.
Fatigue damage is intimately tied to microscopic structural and chemical processes that occur at the points of microdeformations, which develop over time as a material is strained. These processes have been used advantageously as the basis of analytical techniques that measure fatigue damage within metallic materials under simulated service conditions. For example, under conditions of applied cyclic deformation, chemical processes such as the oxidation, leading to passive film formation, and reoxidation, subsequent to passive film rupture, of a metal substrate at points of microdeformation can be probed electrochemically.
Electrochemical fatigue measurement is the subject of U.S. Pat. No. 5,419,201, entitled “Methods and Devices for Electrochemically Determining Metal Fatigue Status”, to Li and Laird. This measurement technique uses a three-electrode electrolyte-filled cell to provide an elecrochemical interface with the material under test. The material is subjected to cyclic mechanical deformations, and during these deformations, the transient current passing through the electrolyte are measured. The current's signature is analyzed to determine the fatigue status of the material.
Another electrochemical technique that has recently been studied is that of electrochemical impedance spectroscopy. “Impedance”, in its most general sense, can be the quotient of any cyclic input perturbation (e.g., mechanical, electrical or optical) and a consequent cyclic output response. A “true” electrical impedance is measured by applying an ac voltage to the material, measuring the response current and phase relationship, and calculating the impedance (Z=V/I). An electrolyte-filled cell having two or three electrodes is used to apply the input voltage and to measure the output current. Impedance values over a suitable spectrum of frequencies can be related to physical and chemical properties of the material.
SUMMARY OF THE INVENTION
One aspect of the invention is a transducer cell array for use in materials testing, such as electromechanical or electrochemical spectroscopy. The array has a number of array layers. A capillary layer has a number of on-conductive capillary elements open at each end. A bottom end of each capillary element may be placed on the surface of a material under test. An electrically conductive reference electrode layer is placed at the upper surface of the capillary array. This reference electrode layer extends down into at least a portion of each capillary element, thereby forming a reference electrode for each capillary element. A contact point array layer is above the reference electrode layer. It has a number of electrically conductive contact points. Each contact point forms a counter electrode for a corresponding capillary element. A contact grid has a number of electrical leads, one lead corresponding to each counter electrode, such that each counter electrode is individually addressable.
REFERENCES:
patent: 4133722 (1979-01-01), Ensanian
patent: 4864329 (1989-09-01), Kneezel et al.
patent: 5006786 (1991-04-01), McKubre et al.
patent: 5419201 (1995-05-01), Li et al.
patent: 5491408 (1996-02-01), Rousseau
patent: 5560811 (1996-10-01), Briggs et al.
patent: 5650058 (1997-07-01), Wenske et al.
patent: 5859537 (1999-01-01), Davis et al.
patent: 6151969 (2000-11-01), Miller et al.
Hudak, Jr. Stephen J.
Miller Michael A.
Baker & Botts L.L.P.
Noori Max
Southwest Research Institute
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