CN1003808B - Scanner for testing micro zone corrosion electric potential current density distribution - Google Patents
Scanner for testing micro zone corrosion electric potential current density distribution Download PDFInfo
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- CN1003808B CN1003808B CN86103043.5A CN86103043A CN1003808B CN 1003808 B CN1003808 B CN 1003808B CN 86103043 A CN86103043 A CN 86103043A CN 1003808 B CN1003808 B CN 1003808B
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Abstract
The present invention belongs to a testing apparatus with local metallic corrosion, which comprises a micro reference electrode with small outside diameter and low internal resistance, a mechanical scanning device and a circuit controlled by a microcomputer. A measuring circuit and software matched with microcomputer control can detect zones of micrometres, microzone potential signals of 10 microvolts and a current density distribution diagram which is clear and intuitionistic, and the quantitative result is obtained. The apparatus has the advantages of high accuracy, high sensitivity, simple structure, low manufacturing cost and strong applicability. The apparatus can be used for researching the local metallic corrosion mechanism of most practical systems and evaluating the local corrosion resistance performance of metallic materials.
Description
The invention belongs to the testing apparatus of metal local corrosion.
For a long time, the measurement of metal surface current potential and electric current distribution at home and abroad corrosion science circle be a difficult problem always.The inventor discloses a kind of microcell Potential distribution analyzer that adopts automatic plane scanning mechanism and micro-stepping motors to drive the microelectrode scanning motion in " WF-II type microcell Potential distribution analyzer " (the 24th the 4th phase of volume of Xiamen University's journal, 457-463 page or leaf).It adopts two micro reference electrodes, adopts two micro-step motors by given pulse, controls sample and micro reference electrode synchronization action respectively.X-y sweep signal control circuit is made up of pulse producer, counter, trigger and gate circuit.Driving circuit is made up of two identical stepper motor ring distributor CH250 of group and power amplifier level, drives x, two stepper motor work of y axle respectively.Sweep velocity, sweep limit and measuring accuracy have been improved.
Because the Potential distribution weak output signal of actual corrosion system, serious interference, scan control and driving circuit are restricted, so the potential image of said apparatus gained only is the equipotential diagram of fixed interval, and be clear inadequately, directly perceived; Its sweep limit is less and fixing, at the needs that can't satisfy actual corrosion system aspect measuring accuracy, data processing and the demonstration as a result.
The objective of the invention is to improve micro reference electrode, utilize microsystem, provide to have to detect the low micro-potential signals that reaches several microns zones and about 10 microvolts in metal surface, noise inhibiting ability is strong, realizes the device of on-site on-line measurement and measurement result smoothing processing.
Micro reference electrode is the critical component of microcell electrochemical measurement, and its parameter greatly influences the measuring accuracy of microcell current potential.The present invention is fixed together two micro reference electrodes, and its tip is positioned on the same straight line perpendicular to sample surfaces, and distance is 300～600 microns, most advanced and sophisticated from sample less than 30 microns, as illustrated in fig. 1 and 2.
Distance between micro reference electrode and the sample is regulated and reading by reading micro actuator (25) about the electrode, and distance is generally less than 30 microns less than 50 microns, and preferably about 10 microns, reading accuracy is 1 micron.
The reading micro actuator, mechanical scanner partly is made up of base plate, slide rail, slide block, column, crossbeam, screw mandrel, motor, bearing hitch bar, specimen holder, electrolytic cell, electrode clamping tool and Controlled by Microcomputer circuit etc. about micro reference electrode and electrode.Scan mode adopts sample to move back and forth in X-direction, and micro reference electrode is in the Y direction stepping, with scanning whole sample surface.Its tenet of dynamic state is: the X-direction stepper motor directly drives screw mandrel with certain rotating speed, promotes the certain distance of slide block translation on slide rail, and the sample on the slide block is also followed same motion.At this moment, Y direction stepper motor rotating certain angle advances micro reference electrode at Y direction stepping certain distance, then X-axis stepper motor counter-rotating, make the sample flyback to the other end, micro reference electrode is further to the Y direction step again, and then the X-axis stepper motor just changes again.And so forth the circulation, micro reference electrode with regard to autoscan the whole sample surface.
Shown in accompanying drawing 3,4 and 5, X-axis slide rail (11) is fixed on the base plate (31), X-axis stepper motor (17) rotates X-axis screw mandrel (13) by bearing (14) and shaft coupling parts (15), so that drive X-axis slide block (12) translation back and forth on the X-axis slide rail, specimen holder (19) and electrolytic cell (20) are fixed on and follow motion together on the X-axis slide block.
Crossbeam (21) is fixed on the column (22), draw runner (23) is housed on the crossbeam, Y-axis slide block (24) can be free to slide on draw runner, electrode reading micro actuator up and down is fixed on the Y-axis slide block, micro reference electrode by electrode clamping tool (26) and electrode up and down the reading micro actuator is connected, be fixed on y-axis stepper motor (29) the driving Y-axis feed screw nut (28) on the motor cabinet (30), Y-axis screw mandrel (27) links, the Y-axis slide block is moved, i.e. also accompany movement of micro reference electrode on draw runner.
X-axis screw mandrel and Y-axis screw mandrel are orthogonal, and sample moves back and forth on X-direction like this, and micro reference electrode is in the Y direction stepping, and the result makes micro reference electrode scan the whole sample surface.
The autoscan process is by Controlled by Microcomputer, and control circuit is made up of programmable parallel I/O interface (PPI), CTC, ring distributor and power amplifier etc.CPU in the microcomputer is connected with peripheral hardware by programmable parallel I/O interface (PPI), external status information (for example micro reference electrode position adjustments key) is by the input port input of PPI, by the forward or reverse of port change X-axis stepper motor and y-axis stepper motor, to regulate the scanning position of micro reference electrode.PPI exports control signal, and control provides pulse signal to X-axis and y-axis stepper motor, with the given parameter running of control motor follow procedure.The control signal of another output port output of PPI cooperates the formation timing pip with CTC, as the impulse source of drive stepping motor, pulsed frequency is the sweep velocity of micro reference electrode by software control with the running speed that changes motor.CTC is operated in count status, also can count the umber of pulse that drives X-axis and y-axis stepper motor respectively, thus the time of control motor operation, the i.e. swash width of micro reference electrode.
Give two groups of identical driving circuits from PPI respectively with the pulse signal of CTC output,, export three groups of series of pulses, respectively through three groups of power amplifier rear drive X-axis and y-axis stepper motor running with out of phase relation earlier by the stepper motor ring distributor.
Reset signal can make scanning be in original state.
Advantage of the present invention is owing to adopt electric heating vertical drawing method to obtain most advanced and sophisticated external diameter less than 10 microns, internal resistance is less than 500K Ω, stability is not inferior to 1 millivolt/day, the Ag/AgCl micro reference electrode of good reversibility makes micro reference electrode can test the low micro-potential signals that reaches several microns zones and about 10 microvolts under the condition near several microns on sample surface.Adopt sample to do X-direction scanning again, micro reference electrode is made the autoscan mode of Y direction stepping, utilize micrometer caliper to repack the X-axis screw mandrel into, utilize clock gauge to repack electrode reading micro actuator up and down into, employing by Controlled by Microcomputer by programmable parallel interface (PPI), CTC, the control Driver Circuit that ring distributor and power amplifier are formed realizes the autoscan process to scanister, so scanning accuracy height, error is less than 10 microns, scan area is big, be not less than 20 * 15 square millimeters, sweep velocity is fast, reaches 4 mm/second, adjustable continuously, 1 micron of the distance adjustment precision of micro reference electrode and sample.Sensitivity of this device and resolution height, rational in infrastructure simple, do and make things convenient for, the efficiency of measurement height, cheap, applicability is wide, has overcome the weak point that present the whole bag of tricks can only be measured the surperficial microcell Potential distribution in the low concentration medium.The software that cooperates suitable metering circuit, can be on-the-spot in corrosion, interference corrosion process not, measure rapidly the corrosion behavior of metal surface, detect the faint galvanochemistry inhomogeneity in metal surface, draw various clear, Potential distribution figures intuitively, bear quantitative result, and can surface measurements microcell current density distributing figure, the anti-local corrosion performance of assessment metal material is one of the most direct the most effective electrochemical method of research metal local corrosion.
For example accompanying drawing 12 is 18-8 rust steel at 5% FeCl
36H
2Three-dimensional current density distributing figure when surperficial origination point corrodes in the O solution.
Accompanying drawing 13 be the 18-8 stainless steel in 0.1NNaCl solution constant potential at+0.10 volt, sample is in corrosion surface equipotential distribution plan when commitment takes place.
Obvious above-mentioned figure is clear, directly perceived.
Accompanying drawing provides one embodiment of the present of invention, by embodiment will the present invention is described further.
The structure of accompanying drawing 1. micro reference electrodes.
Accompanying drawing 2. is measured the micro reference electrode that metal surface microcell electric current distribution is used.
The front elevation of accompanying drawing 3. automatic sweep apparatuses.
The side view of accompanying drawing 4. automatic sweep apparatuses.
Accompanying drawing 5. specimen holders and electrolytic cell.
Accompanying drawing 6. Controlled by Microcomputer circuit block diagrams.
Accompanying drawing 7. step motor control and pulse-generating circuit figure.
Accompanying drawing 8. stepper motor driving circuit figure.
Accompanying drawing 9. position adjustments keys are regulated the initial scanning position workflow diagram of micro reference electrode.
The timing waveform graph of a relation that accompanying drawing 10. is sent by CTC.
Accompanying drawing 11. directly produces the step-by-step impulse circuit diagram by CPU.
Accompanying drawing 12.18-8 stainless steel is at 5% FeCl
36H
2Three-dimensional current density distributing figure when surperficial origination point corrodes in the O solution.
Accompanying drawing 13.18-8 stainless steel is constant potential surface equipotential distribution plan when+0.10V sample is in corrosion commitment takes place in 0.1NNaCl solution.
The structure of micro reference electrode has been described in accompanying drawing 1, about 1 millimeter of external diameter, the about 0.8 millimeter vertical clamping of horminess glass tube of internal diameter is on frame, utilize the method for the vertical control of electric heating to make fusing of glass tube local location and slow the stretching, until breaking, can obtain most advanced and sophisticated external diameter less than 10 microns, internal resistance is less than little glass capillary (2) of 500 kilohms, charge into KCl solution (3) in the pipe, the little glass capillary that charges into KCl solution is connected with encapsulant (5) with another straight tube (4), the general useable glass pipe of straight tube, encapsulant can be used paraffin, is with the good sleeve pipe of light-proofness (7) on the straight tube, and sleeve pipe can be used plastic casing, charge into 1NKCl solution (6) in the straight tube, insert Ag/AgCl contrast electrode (8) again.
The micro reference electrode that is used to measure current density needs two and is fixed together, and scanning simultaneously, as shown in Figure 2, wherein little glass capillary (10) of one is crooked, the tip of two little glass capillaries is positioned on the same straight line perpendicular to sample surfaces, the distance at two tips is generally 200～600 microns, preferably is about 400 microns.
In the accompanying drawing 3,4 and 5, the X-axis screw mandrel preferably utilizes micrometer caliper to convert, and specimen holder and electrolytic cell are fixed on the X-axis slide block, and specimen holder and electrolytic cell are made general available organic glass with the material of acid and alkali resistance corrosion.Electrolytic cell preferably adopts fine thread with being connected of specimen holder, and electrolytic cell can be rotated along Z-axis, so that handle sample and microexamination.The electrode the most handy clock gauge of reading micro actuator up and down converts, and settles a convex twisting in the table illiteracy rotating disk of clock gauge, and stem can promote indicator when covering, and makes micro reference electrode follow fine motion.
Described the Controlled by Microcomputer driving circuit of autoscan process in accompanying drawing 6 to 11, it is made up of programmable parallel I/O interface (PPI) Intel8255, Z80-CTC, stepper motor ring distributor CH250 and power amplifier etc.(32) be cpu bus, (33) be PPI, (34) be CTC, (35) be pulse distribution and shaping circuit, (36) be ring distributor, (37) be power amplifier, (38) are the position adjustments key, and parallel I/O interface (PPI) Intel8255 is a kind of programmable interface chip with three 8 bit ports.In circuit, port A is defined as the way of output, PA
0, PA
1, as the control signal of pulsqe distributor, distribute to X-axis and y-axis stepper motor by the timing pip that CTC produces respectively with decision.Port B also is operated in the way of output, working method in order to control step motor ring distributor CH250, forward and backward with decision X-axis and y-axis stepper motor, it is the moving direction of micro reference electrode, the reset signal of ring distributor also by this port provide, port C is operated in input mode, in order to read in the status information of four position adjustments keys.When the master routine calling station is regulated subroutine, just can be with these four key K
1-4Regulate the initial scanning position of micro reference electrode, its course of work is seen accompanying drawing 9.(39) be " reading state ", (40) for " having key to press? ", (41) are " differentiating and respective handling ", and (42) are " end ", and (43) are " returning ".
The generation and the counting of the stepping timing pip of stepper motor can directly be produced by CPU, see accompanying drawing 11.Whenever writing at 1 o'clock to this peripheral hardware mouth, CPU just produces a step-by-step impulse, and by software timing and counting.The advantage of this method is that hardware is simple, but the CPU holding time is longer.
The generation of the stepping timing pip of stepper motor and the another kind of method of counting are to adopt Z-80CTC timer/counter circuit, produce timing pip by CTC, and the step-by-step impulse of X-axis and y-axis stepper motor is counted.The repetition frequency of timing pip is given by software, to change the running speed of electrode, it is the sweep velocity of micro reference electrode, the maximal value of pulse repetition rate mainly is subjected to stepper motor to start the restriction of frequency, can be unlimited on the minimum principle, but requiring usually has certain sweep velocity, can not be too low.To the counting of X, Y step-by-step impulse, can control the stepping number of times of motor, thus the swash width of control micro reference electrode.
The generation of timing pip is shared, flows to the state that X-axis or y-axis stepper motor then are decided by the port A of PPI.Work as PA
0=1(is 01B) time, y-axis stepper motor is delivered in pulse; Every PA
1=2(is 10B) time, the X-axis stepper motor is delivered in pulse.Because the response speed of photocoupler is slow, and the timing of Z-80CTC output pulse narrower (an about cpu clock cycle) therefore must be finished by the ball bearing made using that diode D, capacitor C and Sheffer stroke gate are formed the timing pip broadening.Width behind the broadening but meets the needs of the reliably working of photocoupler in half of the cycle that may reach high repetition frequency, its oscillogram as shown in Figure 10.
Stepper motor ring distributor and power amplifier have been described in accompanying drawing 8.The CH250 ring distributor is a kind of digital integrated circuit chip of three-phase stepper motor control of monolithic.Change the state of 14,15 pin, just can make motor make forward and backward, step-by-step impulse is imported from 7 pin.Power amplification circuit amplifies in order to the signal to ring distributor output, to adapt to the needs of stepper motor.From 8255 and the Xcp of Z-80CTC output, X
OONTR, Ycp, Y
CONTRLPulse signal is given two groups of identical power amplifiers respectively, at first be connected with photocoupler by open-collector gate, after utilizing J003 to carry out level conversion again, send into stepper motor ring distributor CH250, ring distributor is exported three groups of series of pulses with out of phase relation, respectively through three grades of power amplifier rear drive X-axis and y-axis stepper motor running.Reset signal can make scanning be in original state.Open-collector gate can be selected 74LS05 for use, and photocoupler can be used GO102.
CH250 preferably is connected into two triple time working methods (3 ° of step corners), can make motor rotationization more stable.With Z80-CTC produce timing pip and respectively to X, Y step-by-step impulse counting, reached regularly, stroke all can be by software control, and CPU expends time in less, is the optimal allocation of hardware and software.Between motor and microcomputer, insert photocoupler, reduced interference, guarantee the reliability service of microcomputer microcomputer.
In the accompanying drawing 12 in the position at current potential peak corresponding to each corrosion activity point of sample surfaces.Scan area is selected 7 * 7 square millimeters, 152 millivolts of average potential.
Circle center position in the accompanying drawing 13 in the equipotential distribution plan is all corresponding to each corrosion activity point of sample surfaces.Scan area is also elected 7 * 7 square millimeters as, and average potential is 199 millivolts.
Claims (4)
1, the scanister of testing micro zone corrosion electric potential current density distribution, form by automatic plane scanning mechanism, X-Y sweep signal control circuit and driving circuit, be provided with two micro reference electrodes, adopt two micro-step motors by given pulse, control sample and micro reference electrode respectively, X-Y sweep signal control circuit is made up of pulse producer, counter, trigger and gate circuit, and driving circuit is made up of ring distributor CH250 and power amplifier level, it is characterized in that
(a) two micro reference electrodes are fixed together, and its tip is positioned on the same straight line perpendicular to sample surfaces, and distance is 300～600 microns, most advanced and sophisticated from sample less than 30 microns;
(b) by programmable parallel I/O interface PPI control, the output control signal control CTC of PPI provides the distribution of pulse signal to the autoscan process to x, y axle two stepper motors by the CPU in the microcomputer.
2, scanister as claimed in claim 1, the distance between two tips that it is characterized in that two micro reference electrodes is 350～450 microns, most advanced and sophisticated from sample less than 10 microns.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN86103043.5A CN1003808B (en) | 1986-04-28 | 1986-04-28 | Scanner for testing micro zone corrosion electric potential current density distribution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN86103043.5A CN1003808B (en) | 1986-04-28 | 1986-04-28 | Scanner for testing micro zone corrosion electric potential current density distribution |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN86103043A CN86103043A (en) | 1986-11-12 |
| CN1003808B true CN1003808B (en) | 1989-04-05 |
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ID=4801928
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN86103043.5A Expired CN1003808B (en) | 1986-04-28 | 1986-04-28 | Scanner for testing micro zone corrosion electric potential current density distribution |
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| Country | Link |
|---|---|
| CN (1) | CN1003808B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1035735C (en) * | 1995-07-04 | 1997-08-27 | 厦门大学 | Metal/polymer composite material interface electric potential distribution measuring device |
| US6623611B1 (en) * | 2002-11-20 | 2003-09-23 | General Electric Company | Zircalloy tipped ECP sensor electrode |
| CN100339637C (en) * | 2005-11-22 | 2007-09-26 | 沈阳航空工业学院 | Automatic monitoring and evaluating system for interference corrosion of embedded metal pipeline |
| CN111360265B (en) * | 2018-12-06 | 2023-01-20 | 广州中国科学院先进技术研究所 | Preparation method of SLM porous metal three-dimensional surface film with nano PPy biological activity |
-
1986
- 1986-04-28 CN CN86103043.5A patent/CN1003808B/en not_active Expired
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| Publication number | Publication date |
|---|---|
| CN86103043A (en) | 1986-11-12 |
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