CN108444901A - A kind of critical pitting temperature assay method - Google Patents
A kind of critical pitting temperature assay method Download PDFInfo
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- CN108444901A CN108444901A CN201810266738.0A CN201810266738A CN108444901A CN 108444901 A CN108444901 A CN 108444901A CN 201810266738 A CN201810266738 A CN 201810266738A CN 108444901 A CN108444901 A CN 108444901A
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- assay method
- temperature
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- critical pitting
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- 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
- G01N17/02—Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement
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Abstract
A kind of critical pitting temperature assay method, include the following steps, test button is immersed as working electrode in medium and is stablized to current potential, build the galvanic circle including working electrode and medium, galvanic circle is powered, and is heated to medium, record current, temperature, the relationship of time, until electric current is mutated, temperature when matching current is mutated.It solves that existing pitting temperatures assay method cost is excessively high, measures not smart problem.
Description
Technical field
The present invention relates to electrochemical field more particularly to a kind of critical pitting temperature measurement sides of suitable electrochemical analysis
Method.
Background technology
Spot corrosion is also known as pitting corrosion and pitting corrosion, and spot corrosion (Pitting) is that metal surface is relatively concentrated in a very little portion
The local corrosion of position.Metal loss amount very little when spot corrosion, though equipment occur perforation destroy its equipment it is weightless if very little,
Also it is difficult to predict equipment life with the Reducing thickness of wall-thickness measurement.Spot corrosion simultaneously is due to its special dynamic process, reaction
It is accelerated under autocatalysis, spot corrosion is once occur, and solution rate is quite big in hole, so the harmfulness of spot corrosion is very
Greatly, the generation for often suddenly leading to accident is destructive and larger one of the local corrosion form of hidden danger.
Evaluation for metal material pitting resistance, generally use electrochemical test method measure the pitting potential of material
And critical pitting temperature.It is relatively simple to measure spot corrosion electric potential method, such as GB/T 17899-1999《Stainless steel pitting potential measures
Method》Stainless steel pitting potential is measured using potentiodynamic technique, but the defects of experimental result precision is low, poor repeatability.Critical spot corrosion
Temperature can preferably reflect pitting resistance performance of material.Such as patent " a kind of nickel-base alloy pitting resistance evaluation method and device
For CN201410457514.X " using Eb100 values are measured, it is absolute critical spot corrosion temperature to take corresponding temperature when Eb100 value mutations
Degree.Patent " a kind of method CN201310130483.2 of evaluating pitting resistance performance of material " is reached for the first time by measuring current density
The temperature of 1 × 10-4A/cm2, as material critical pitting temperatures." one kind is for measuring the critical point of stainless steel tube outer surface for patent
The fixture CN201610128590.5 " of erosion temperature discloses a kind of folder for testing outer surface of steel tube material critical pitting temperatures
Tool.
Invention content
For this reason, it may be necessary to provide a kind of electrochemistry critical pitting temperature assay method of other style, solves existing pitting temperatures and survey
Determine that method cost is excessively high, measures not smart problem.
A kind of critical pitting temperature assay method, includes the following steps, immerses medium using test button as working electrode
In stablize to current potential, build the galvanic circle including working electrode and medium, galvanic circle is powered, and is heated to medium,
Record current, temperature, the relationship of time, until electric current is mutated, temperature when matching current is mutated.
Further, further include step, test button coated with insulator so that working electrode only have a working face with
Media contact, the contact surface are plane.
Specifically, the insulator includes thermosetting plastics, epoxy resin.
Specifically, further include step, working face is polished.
Preferably, include the following steps, heating water bath is carried out to medium, water bath device heating rate is (1-2) ± 0.3
℃/min。
Preferably, further include step, working electrode is first carried out cathodic polarization by galvanic circle before being powered.
Optionally, the medium selects 3.5% sodium chloride solution.
Further, further include step, select different as cast condition temperature solid-solution materials as test button, different metal is tried
Sample makes working electrode and is tested.
It is different from the prior art, above-mentioned technical proposal plays the effect for preferably measuring electrochemical sample critical pitting temperature
Fruit solves the problems, such as sample spot corrosion temperature measuring.And above method requirement equipment is few, source is easy to get, and is not necessarily to electrochemistry work
Make station and adds special temperature control module, it is of low cost.
Description of the drawings
Fig. 1 is the critical pitting temperature assay method flow chart described in specific implementation mode；
Fig. 2 is the critical pitting temperature measurement device figure described in specific implementation mode；
Fig. 3 is current potential-time variation diagram described in specific implementation mode；
Fig. 4 is the electrochemical sample external member structure figure described in specific implementation mode.
Reference sign：
1, pvc pipe；
2, electrochemical sample；
3, curing agent；
4, glass；
502, glue；
6, syringe.
Specific implementation mode
For the technology contents of technical solution, construction feature, the objects and the effects are described in detail, below in conjunction with specific reality
It applies example and attached drawing is coordinated to be explained in detail.
Referring to Fig. 1, introducing a kind of critical pitting temperature assay method in the present embodiment, include the following steps, S100 will
Test button is immersed as working electrode in medium to be stablized to current potential, here can be with referring to Fig.2, the work that test button makes in figure
It is immersed in medium as electrode, then carries out step S102 and build leading including working electrode and medium as shown in Figure 2
Electrical circuit, galvanic circle further include electrochemical workstation, to electrode, conducting wire etc..Setting constant potential is 600mV, and is walked
Rapid S104 heats medium, and the mode of heating can have very much, can be by medium in our some embodiments
The heating water bath pattern of outer water proof heating, selects heating water bath pattern that medium is enabled to be heated evenly on the whole, temperature-controllable.
The electrode of device can access recorder, while open constant temperature water bath apparatus and potentiostatic scanning, sweep current-time graph and
Temperature-time curve carries out step S106 recording mediums temperature change and the relationship with the time, until electric current is mutated,
Temperature when matching current is mutated.By the above method, the present invention can accurately control the actual temp of medium, be made by water-bath
It is heated to obtain homogeneous media, it is whole to turn down temperature.Electric current mutates after medium reaches certain temperature, the method for the present invention energy
Medium temperature when the enough time for more accurately measuring critical spot corrosion appearance and critical spot corrosion occur, then play better survey
The effect for determining electrochemical sample critical pitting temperature solves the problems, such as sample spot corrosion temperature measuring.And above method requirement
Equipment is few, source is easy to get, and special temperature control module is added without electrochemical workstation, of low cost.
Further include step for the more acurrate critical pitting temperature for measuring sample in some other further embodiment,
Test button coated with insulator, in specific embodiment, as long as insulator can play isolation medium and test button
Effect, optional range include thermosetting plastics, epoxy resin, and PVC plastic shell and epoxy preferably may be used here
The insulator of resin filling, cost of manufacture is cheap, and resistance is electrically good.Insulator coats so that working electrode only has a working face and is situated between
Matter contacts, and the contact surface is plane.Working electrode only has the electricity of a plane and each contact point of media contact then thereon
It is all vertical with contact surface to flow direction, enables to the electrodynamics process on entire contact surface more balanced, eliminates other and connect
Interference of the possible pitting problem of contacting surface to experimental result, so that obtained experimental result data is more accurate.
In order to enable the working face of test button is more smooth, in the particular embodiment, we also carry out step, are making
Make to be polished working face when working electrode.The step of carrying out sanding and polishing to working face, can better ensure that working face
Flatness so that the measurement result of pitting temperatures is more accurate.
In other preferred embodiments, our assay method includes the following steps, when carrying out heating water bath to medium,
Water bath device heating rate is (1-2) ± 0.3 DEG C/min.Water makes the heating speed of heating water bath due to the characteristic of its high specific heat capacity
Rate more controls slowly and more easily, and it is per minute in 1-2 degree to will heat up rate control, and it is accurate will not to lead to not very much record soon
True pitting temperatures will not cause very much to waste time slowly because of heating.
Preferably, further include step, working electrode is first carried out cathodic polarization by galvanic circle before being powered.Metal surface is general
There is an oxidation film, it is exposed that when test, which needs metal material, and the effect of cathodic polarization is to remove the oxidation film of specimen surface,
So that test is accurate.
Optionally, the medium selects 3.5% sodium chloride solution.
Further include step in some other further embodiment, selects different as cast condition temperature solid-solution materials as metal
Sample makes working electrode to different metal sample and tests.In the embodiment shown in fig. 3, we show including casting
1050 ° of state temperature, 1100 °, the test buttons of 1150 ° of a variety of situations, through the above scheme can also be in specific embodiment
In the evaluations of pitting temperatures is carried out to the test buttons of different as cast condition temperature.
In the embodiment shown in fig. 4, a kind of electrochemical sample set that can carry out metal spot corrosion temperature test is disclosed
Part, including plastic tube 1, electrochemical sample 2 cure oxidant layer 3；The electrochemical sample 2 is located in plastic tube 1, the plastic tube
A bottom surface for hollow tubular, electrochemical sample 2 is parallel with a bottom surface of plastic tube 1, is filled out between electrochemical sample 2 and plastic tube 1
Filled with curing agent, a bottom surface of the curing agent is parallel with a bottom surface of plastic tube；There are copper wire, institute in the electrochemical sample
State copper wire and penetrate electrochemical sample, and extend to outside plastic tube, copper wire can be used for being connected to after completing external power supply or
Conductor wire is done on person's electrochemical workstation to be used.Copper wire is arranged by way of cold connection in electrochemical sample, and such as perforation is inserted
Enter etc..In actual manufacturing process, in order to ensure that above-mentioned plastic tube, electrochemical sample, the bottom surface of curing agent are smooth, flat
Together；The installation that electrochemical sample external member can be carried out in a smooth flat, such as in our embodiment, by the work of sample
Face (being bottom surface in figure) and pvc pipe are placed on the surface of glass 4 and apply upper glue layer 502 jointly, and sample and pvc pipe are sticked to
On glass, as shown in Figure 4.Then curing agent can also be injected to the middle layer of plastic tube and electrochemical sample by syringe 6
3, epoxy resin+polyamide can be used as curing agent in preferred embodiment, 15% (quality percentage can be added in the epoxy
Number) polyamide, stir evenly after (pay attention to speed otherwise to easy to produce bubble slowly) through syringe, then slowly live to note
Enter in pvc pipe and (is careful not to too soon, otherwise have bubble).Naturally dry after the completion of injection forms solidification oxidant layer.Again will later
Entire external member is struck down from glass, obtains can be used in the side cladding that pitting temperatures assay method uses, bottom surface conduct
The working electrode of working face and media contact.Each Coating combination of electrochemical sample of above-mentioned design is close, can complete spot corrosion temperature
The measurement operation of degree.
Further include sleeve in some other preferred embodiment, the sleeve is inserted vertically into curing agent, the copper wire
A part be arranged in sleeve.As shown in Figure 4, copper wire lower end passes through electrochemical sample, upper part to be arranged in sleeve
Extend outwardly, copper wire is protected by sleeve design, the service life of this external member can be promoted, preferably completes pitting temperatures and measure
Work.
It should be noted that although the various embodiments described above have been described herein, it is not intended to limit
The scope of patent protection of the present invention.Therefore, based on the present invention innovative idea, to embodiment described herein carry out change and repair
Change, or using equivalent structure or equivalent flow shift made by description of the invention and accompanying drawing content, it directly or indirectly will be with
Upper technical solution is used in other related technical areas, is included within the protection domain of patent of the present invention.
Claims (8)
1. a kind of critical pitting temperature assay method, which is characterized in that include the following steps, using test button as working electrode
Immerse in medium and stablize to current potential, build the galvanic circle including working electrode and medium, galvanic circle is powered, and to medium into
Row heating, record current, temperature, the relationship of time, until electric current is mutated, temperature when matching current is mutated.
2. critical pitting temperature assay method according to claim 1, which is characterized in that further include step, metal is tried
Sample is coated with insulator so that it is plane that working electrode, which only has a working face and media contact, the contact surface,.
3. critical point temperature assay method according to claim 1, which is characterized in that the insulator includes thermosetting property modeling
Material, epoxy resin.
4. critical pitting temperature assay method according to claim 1, which is characterized in that further include step, to working face
It is polished.
5. critical pitting temperature assay method according to claim 1, which is characterized in that include the following steps, to medium
Heating water bath is carried out, water bath device heating rate is (1-2) ± 0.3 DEG C/min.
6. critical pitting temperature assay method according to claim 1, which is characterized in that further include step, galvanic circle
Working electrode is first subjected to cathodic polarization before being powered.
7. critical pitting temperature assay method according to claim 1, which is characterized in that the medium selects 3.5% chlorine
Change sodium solution.
8. critical pitting temperature assay method according to claim 1, which is characterized in that further include step, selection is different
As cast condition temperature solid-solution material makes working electrode as test button, to different metal sample and tests.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810266738.0A CN108444901A (en) | 2018-03-28 | 2018-03-28 | A kind of critical pitting temperature assay method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810266738.0A CN108444901A (en) | 2018-03-28 | 2018-03-28 | A kind of critical pitting temperature assay method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN108444901A true CN108444901A (en) | 2018-08-24 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810266738.0A Pending CN108444901A (en) | 2018-03-28 | 2018-03-28 | A kind of critical pitting temperature assay method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108444901A (en) |
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2018
- 2018-03-28 CN CN201810266738.0A patent/CN108444901A/en active Pending
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