GB2054865A - Process for the rapid determination of the resistance of corrosion of an electrophoretic coating, and apparatus for its accomplishment - Google Patents
Process for the rapid determination of the resistance of corrosion of an electrophoretic coating, and apparatus for its accomplishment Download PDFInfo
- Publication number
- GB2054865A GB2054865A GB8019606A GB8019606A GB2054865A GB 2054865 A GB2054865 A GB 2054865A GB 8019606 A GB8019606 A GB 8019606A GB 8019606 A GB8019606 A GB 8019606A GB 2054865 A GB2054865 A GB 2054865A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cell
- specimen
- corrosion
- coating
- electrodes
- 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.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 46
- 230000008569 process Effects 0.000 title claims abstract description 46
- 238000005260 corrosion Methods 0.000 title claims abstract description 38
- 230000007797 corrosion Effects 0.000 title claims abstract description 38
- 238000000576 coating method Methods 0.000 title claims abstract description 36
- 239000011248 coating agent Substances 0.000 title claims abstract description 32
- 239000003792 electrolyte Substances 0.000 claims abstract description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims abstract description 15
- 229910052751 metal Inorganic materials 0.000 claims abstract description 6
- 239000002184 metal Substances 0.000 claims abstract description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 12
- 239000011780 sodium chloride Substances 0.000 description 10
- 239000011347 resin Substances 0.000 description 7
- 229920005989 resin Polymers 0.000 description 7
- 238000001962 electrophoresis Methods 0.000 description 6
- 239000005062 Polybutadiene Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000010422 painting Methods 0.000 description 4
- 229920002857 polybutadiene Polymers 0.000 description 4
- 230000007246 mechanism Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000004020 conductor Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- -1 for example Substances 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000007591 painting process Methods 0.000 description 1
- 238000011158 quantitative evaluation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- 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
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Biodiversity & Conservation Biology (AREA)
- Ecology (AREA)
- Environmental & Geological Engineering (AREA)
- Environmental Sciences (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
Abstract
A process for a rapid determination of the resistance to corrosion of an electrophoretic coating, which process comprises at least a stage comprising the following operations:- immersing a specimen comprising a metal support 6 coated with the coating 5 into an electrolyte 2 of an electrolytic cell, into which a solution of a hydroxide has been introduced to obtain an alkaline medium in the cell with a pre-determined hydroxide concentration, electrically connecting the specimen to the negative pole of the current feeder electrode of the said cell, so that the specimen itself forms the cathode of the cell, and determining the time required to detach a portion of the coating from the support and to cause the corrosion of the support until a predetermined current is obtained between the electrodes of the cell. <IMAGE>
Description
SPECIFICATION
Process for the rapid determination of the resistance to corrosion of an electrophoretic coating, and apparatus for its accomplishment
The present invention relates to a process for the determination of the resistance to corrosion of an electrophoretic coating, obtained both by anodic and cathodic treatments, by means of which it is possible to carry out on specimens very rapid measurements of the resistance to corrosion, such as those which are required for the control of industrial painting lines.
As it is well-known, processes of deposition of resin layers of various types on metal supports by means of anodic and cathodic electrophoresis are widely used in painting, in particular in the painting of motor vehicle bodies; the first layer, which is in direct contact with the surface of the body, is, in fact, constituted by a resin deposited by electrophoresis, and to this end usually the anodic electrophoresis is utilized, with which it is possible, for example, to obtain a first coating of polybutadiene resins having thicknesses up to 30 . 35 micron.
In controlling such painting processes it is quite important to evaluate the quality of the electrophoretic coating, in order to ensure a perfect protection against corrosion agents of the support onto which the coating has been deposited.
As it is well-known, the determination of the resistance to corrosion of the said coatings is usually carried out by exposing, first, specimens formed by a suitably coated plate of the material of the support, to the action of a corrosion agent (formed, usually, by a saline fog obtained from a solution of sodium chloride in water), and then measuring the dimensions of the traces of corrosion thus obtained, according to the modalities fixed by the norm ASTM B 117.
Therefore, the corrosion takes place electrochemically (oxidation of the iron and reduction of the oxygen), by the action of the moisture and the oxygen which contact the surface of the specimen through the pores of the coating or through suitable notches formed in this latter); the speed with which this phenomenon takes place is considerably increased by the presence of the sodium chloride in the said fog.
The evaluation of the resistance to corrosion by means of this process gives rise to numerous disadvantages.
First of all, the time required for the accomplishment of the process is quite long, in the order of hundreds of hours; this is, in fact, the time which is necessary, in the test conditions described, for obtaining traces of corrosion having measurable dimensions.
Moreover, this process cannot be used for obtaining, in a continuous manner, data useful for the control of a continuous painting line in which it is necessary to undertake an action as soon as a disadvantageous variation of the quality or the deposited coatings takes place; in fact, because of
the considerably long time required for carrying
out each test, actions can be underaken only after having painted a considerable quantity of products whose coating is of unacceptable quality.
Finally, the process described hereinabove usually does not allow a very accurate quantitative evaluation of the resistance to corrosion, because of the rather high dispersion of the results to which the process gives rise; therefore, with this process it is not possible to obtain data suitable for a rigorous comparison of coatings whose characteristics are little different.
It is an object of the present invention to provide a process for quickly determining the resistance to corrosion of an electrophoretic coating, which will allow avoiding the disadvantages mentioned hereinabove.
Another object of the present invention is to provide an apparatus for the accomplishment of the process according to the invention.
The process according to the present invention is characterized in that it comprises at least a stage including the following operations: immersing a specimen comprising a metal support coated with the said coating into an electrolyte of an electrolytic cell, into which a hydroxide has been introduced in solution to obtain in the said cell an alkaline medium with a pre-established concentration of hydroxide, electrically connecting the said specimen to the positive pole of the current feeder of the said cell, so that the specimen itself will form the cathode of the cell, and maintaining the said specimen within the said electrolyte for the time which is necessary to produce the detachment of a portion of the said coating from the support and to let the corrosion of the support go on till an electric conductivity between the electrodes of the said cell is obtained which is apt to establish between them a circulation of a pre-established current.
For a better understanding of the process according to the present invention, the fundamental stages of the process will now be described in detail with reference to an embodiment of an apparatus suitable for the accomplishment of the process, shown by way of non limiting example in the accompanying drawings, in which:
FIGURE 1 is a diagrammatic perspective view of the apparatus according to the invention,
FIGURE 2 shows some curves of experimental results obtained by means of the apparatus shown in Fig. 1,and FIGURE 3 shows a nomogram apt to allow an immediate comparison of the data obtained by means of the process according to the invention with those obtained by means of a prior art process.
Before describing the stages of the process according to the invention it is suitable to examine the apparatus for the accomplishment of the said process.
This apparatus substantially comprises an electrolytic cell, indicated generally by reference numeral 1 , filled with an electrolyte 2 obtained substantially by means of a solution of a hydroxide in water; in order to provide an alkaline medium in the said cell.
The said hydroxide may be of any metal, for example a sodium hydroxide; although it is preferable to reach in the electrolyte a concentration of hydroxide of about 1,25 equivalent grams/liter of OH, the said concentration is not critical. It has been noticed that when the hydroxide is sodium hydroxide the concentration of this hydroxide should conveniently be of about 50 g/l.
The cell is provided with two anodes 3 of any suitable material, for example, steel, disposed adjacent two opposite walls of the cell and electrically connected to the positive pole of a suitable current feeder 4. The said cell is provided also with means (not shown) apt to support within the electrolyte a specimen 5 and to connect it electrically with the negative pole of the feeder 4,
in order that it forms the cathode of the cell;
conveniently, the specimen 5 is arranged between the anodes 3, as can be clearly seen in Fig. 1.
The said specimen is formed by lamination of the support material on which the coating being tested has been deposited by electrophoresis; the coating may be any layer deposited by electrophoresis, either anodic or cathodic; thus, the layer may be a thin layer of any resin apt to be deposited by such treatment. In the case of anodic electrophoresis, the said coating may conveniently be formed by a layer of polybutadiene resins, having the maximum thickness of 30-35 micron.
Conveniently, the specimen 5 has its edges 6 covered by a suitable protection material, such as paraffine, in order both to exclude the edge regions from the test and to define on it two opposite substantially rectangular surfaces having a pre-established area; an electric conductor may be connected, in any suitable way, to the said support and serves for an immediate electric connection of the specimen to the said means.
These latter may have any structure, provided they are apt to support the specimen in a preestablished position within the cell 1 and to connect it electrically to the feeder 4; they may comprise guides, stops, electric connection members and the like, normally used in means of this type.
The apparatus may also comprise a time counter 7, apt to be activated when the specimen 5 is introduced into the cell 1 (or when current is supplied by the feeder 4) and to be desactivated by an electric signal emitted when a preestablished current flows between the electrodes 3 and 5 of the cell. The said counter is conveniently an electronic counter, for example of the digital type, activable manually. In order to generate the said desactivation electric signal, cell
1 and electrodes 3 and 5 are part of an electric circuit (not shown) comprising two points whose voltage difference is compared with a reference voltage; the said desactivation signal is emitted when the said reference voltage is reached between the said two points.The circuit is conceived in such a way that the said condition (equality between the voltage differences between the said two points and the reference voltage) will arise only when between the electrodes 3 and 5 a current circulates which has a pre-established value, for example 1 ampere.
The process according to the invention, accomplished by means of the apparatus described hereinabove, takes place in the following manner.
A specimen 5, prepared as described hereinabove, is introduced into the cell 1 and is connected to the said support means, and at the same time the time counter 7 is activated.
The solution of the electrolyte 2 passes through the pores of the coating (or through the eventual notches formed in the coating in accordance with modalities fixed by some standardized norms) and the corrosion of the support initiates. The corrosion takes place according to the same cathodic etching mechanism according to which it proceeds both in the conditions of the outer ambient and in the the saline fog process described before.
However, the corrosion takes place at a very high speed, owing both to the alkaline medium created by the addition of the hydroxide to the electrolyte and the cathodic connection of the specimen. In fact, it has been found that when in the interface coating/support surface there is, from the chemical point of view, a high basicity and, from the electrical point of view, a distribution of negative voltages (cathodic areas), the detachment of the coating occurs easily and the corrosion rate as particularly high.
It has, however, to be noted that, on the other
hand, the said two conditions are not created artfully without any connection with the
mechanism of the corrosion in the case of She
exposition of the specimen to the outer ambient or to that of the saline fog. In fact, it has been found that in both said cases the corrosion can proceed,
even at a very modest rate, only when cathodic
areas are created, through normal electrochemical
phenomena, in the interface coating/support surface; it has been noticed that in these areas the
basicity is always rather high and higher than that of the other areas.
Therefore, with the process of the present invention modalities have been contrived for increment, to a substantial extent, the rate at which normally the corrosion of the coating
proceeds in the outer ambient, without substantially altering the mechanism with which the corrosion takes place in the said ambient. It follows that the results obtainable by means of the
process according to the invention, not only give a quantitative indication of the resistance to
corrosion as if it was taking place in the outer ambient, but also give indications comparable with those which are obtained by means of the saline fog exposition process described
hereinabove.
As the corrosion of the specimen proceeds and consequently the area of its surfaces loosing their coating increases, there is an increase of the current which flows in the electrolyte 2 between the electrodes 3 and 5.
On the ground of the process according to the invention, the resistance to corrosion of the specimen is evaluated on the basis of the time required to let the corrosion proceed to a sufficient degree for obtaining a flow of a pre-established current in the electolyte and between the electrodes. The value of this current may be chosen in any way whatever, for example by means comparison with the saline fog test process.With an electrolytic cell having the capacity of about two litres and with specimens coated with a polybutadiene resin and having surfaces of 1 50 x 70 mm (free surfaces between the edges 6 of about 134 cm2), with steel anodes having the dimensions 25 x 120 x 0,8 mm and disposed at a distance of 120 mm, and with a concentration of sodium hydroxide of 50 g/l in the electrolyte, it has been deemed suitable to fix at
1 ampere the value of the said current.
Under these circumstances, the time required for evaluating the resistance to corrosion of each specimen was in the order of 30 minutes: the results obtained in the said experimental conditions are shown in the diagrams of Fig. 2, whose curves indicate the values of the currents measured between the electrodes 3 and 5, as a function of the test time, for four different specimens. From these results it can be noticed that for current values of 1 ampere there is a considerable differentiation between the resistances to corrosion of the various specimens; obviously, to the increase of the test time required for causing a 1 ampere current to flow between the electrodes, correspond higher resistances to corrosion.
With the process according to the present invention, when the aforementioned condition (flow of a pre-established current between the electrodes 3 and 5) is obtained, between the said points of the electric circuit described hereinabove there is also obtained a voltage difference sufficient for the time counter to emit a desactivation signal. In this way, the count of the time is stopped and the operator can, at any moment, carry out on the counter the reading of the test time which, as said before, constitutes a parameter proportional to the resistance to corrosion.
Obviously, it is possible to put into relation the results obtained by means of the process according to the invention with those obtained by means of the conventional process with exposition to a saline fog, in order to to ascertain to which dimensional value of the corrosion trace on a specimen subjected to tests with this latter process corresponds, in the same experimental conditions, the test time evaluated, as indicated above, with the first mentioned process. This correlation can be found in various manners by means of experimental comparison tests which do not require any further description.
By way of example, in the nomogram of Figure 4 there are indicated the results of the correlation found between the two processes by means of tests carried out in the aforementioned experimental conditions on specimens coated with polybutadiene resin coatings having thicknesses between 1 5 and 25 micron; the results shown in Figure 4 relate to the comparison by means of tests carried out in accordance with the saline fog exposition process in which the duration of the exposition was of 200 hours.
The comparison of the results obtained with the two processes may be carried out by means of a straight line like the one traced by a dashed line in the nomogram; as indicated by this straight line, to a test carried out in accordance with the process of the invention, whose time is indicated by a point of the scale on the left-hand side and whose coating thickness is indicated by a point of the scale on the right-hand side, corresponds a test carried out by means of the saline fog exposition process which leads to a dimension of the corrosion trace which can be read on central scale, at the point at which it is intersected by the straight line joining the aforementioned points.
It is clear that each of the described stages of the process according to the present invention may be modified and the succession of these stages may be varied, without departing from the scope of the invention.
Claims (9)
1. A process for a rapid determination of the resistance to corrosion of an electrophoretic coating, which process comprises at least a stage comprising the following operations: immersing a specimen comprising a metal support coated with the coating into an electrolyte of an electrolytic cell, into which a solution of a hydroxide has been introduced to obtain an alkaline medium in the cell with a pre-determined hydroxide concentration, electrically connecting the specimen to the positive pole of the current feeder electrode of the said cell, so that the specimen itself forms the cathode of the cell, and maintaining the specimen within the said electrolyte for the time required to detach a portion of the coating from the support and to cause the corrosion of the support until an electric conductivity between the electrodes of the cell is obtained which establishes between them a pre-determined current.
2. A process as claimed in claim 1 wherein the electrolyte has a hydroxide in a concentration of between 0.2 and 3 equivaient g/l.
3. A process as claimed in claim 1 or claim 2 wherein the hydroxide is sodium hydroxide and the concentration of sodium hydroxide in the electrolyte is between 8 and 120 g/l.
4. A process as claimed in any one of the preceding claims wherein the said time is the time which is necessary to produce the detachment of a portion of the coating from the support and sufficient to obtain between the electrodes of the cell an electric conductivity which causes a current of 1 ampere to flow between the electrodes.
5. An apparatus for the rapid determination of the resistance to corrosion of an electrophoretic coating, which apparatus comprises an electrolytic cell into the electrolyte of which a solution of a hydroxide has been introduced to obtain an alkaline medium in the cell with a pre-determined hydroxide concentration, the cell being arranged to use as its cathode a specimen comprising a metal support coated with the coating, and a measuring means to measure the current flowing between the electrodes of the cell, the resistance to corrosion of the specimen being measured on the basis of the time required to produce the detachment of a portion of the coating to an extent sufficient to obtain between the electrodes of the cell an electric conductivity which causes a pre-determined current to flow between them.
6. An apparatus as claimed in claim 5 which comprises a time counter which activates when the specimen is introduced into the cell and which is deactivated by an electric signal which is emitted when the pre-determined current flows between the electrodes of the cell.
7. An apparatus as claimed in claim 6 wherein the electric signal is emitted when a predetermined reference voltage is obtained between the electrodes and the electrolyte of the electrolytic cell.
8. A process as claimed in claim 1 substantially as hereinbefore described with reference to the accompanying drawings.
9. An apparatus as claimed in claim 4 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT68325/79A IT1118991B (en) | 1979-06-21 | 1979-06-21 | PROCEDURE FOR THE QUICK DETERMINATION OF THE CORROSION RESISTANCE OF AN ELECTROPHORESIS COATING AND EQUIPMENT SUITABLE TO CARRY OUT SUCH PROCEDURE |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2054865A true GB2054865A (en) | 1981-02-18 |
| GB2054865B GB2054865B (en) | 1983-09-07 |
Family
ID=11308985
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8019606A Expired GB2054865B (en) | 1979-06-21 | 1980-06-16 | Process for the rapid determination of the resistance of corrosion of an eletrophoretic coating and apparatus for its accomplishment |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE3022634A1 (en) |
| FR (1) | FR2459469A1 (en) |
| GB (1) | GB2054865B (en) |
| IT (1) | IT1118991B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102006028442A1 (en) * | 2006-06-21 | 2008-01-03 | Bayerische Motoren Werke Ag | Method for determining the damage to the electrocoating layer of a filler-free automotive paint by the action of light |
| US7422678B2 (en) * | 2003-10-21 | 2008-09-09 | Teledyne Licensing, Llc | Evaluation of the corrosion inhibiting activity of a coating |
| CN105092461A (en) * | 2015-09-14 | 2015-11-25 | 北京科技大学 | Metal corrosion high-throughput characterization experimental apparatus based on image |
| CN107024422A (en) * | 2016-01-29 | 2017-08-08 | 立邦涂料（中国）有限公司 | A kind of moisture resistance properties test device of aqueous woodware paint |
| RU2770844C1 (en) * | 2021-09-24 | 2022-04-22 | Публичное акционерное общество "Газпром" | Method for evaluating the protective efficiency of compositions inhibiting stress corrosion cracking in pipe steels |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3143780B2 (en) * | 1996-06-10 | 2001-03-07 | 本田技研工業株式会社 | Corrosion resistance test method and electrolysis tester for specimen consisting of metal material and coating film |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1109322A (en) * | 1954-07-26 | 1956-01-24 | Carnaud & Forges | Improvement in the electrolytic determination of the level of a protective metal on iron |
| US3223598A (en) * | 1962-11-23 | 1965-12-14 | Germaine F Jacky | Method for determining the adhesion of metal plating |
| US3439531A (en) * | 1966-02-11 | 1969-04-22 | Us Navy | Method for simulating environmental conditions |
| DD95811A3 (en) * | 1971-02-05 | 1973-02-20 | ||
| SE416238B (en) * | 1977-06-10 | 1980-12-08 | Stig Allan Alfredsson | PROCEDURE FOR DETERMINING CRITICAL TEMPERATURES FOR CORROSION AND DEVICE FOR EXECUTION OF THE PROCEDURE |
| US4229264A (en) * | 1978-11-06 | 1980-10-21 | The Boeing Company | Method for measuring the relative etching or stripping rate of a solution |
-
1979
- 1979-06-21 IT IT68325/79A patent/IT1118991B/en active
-
1980
- 1980-06-16 GB GB8019606A patent/GB2054865B/en not_active Expired
- 1980-06-18 DE DE19803022634 patent/DE3022634A1/en not_active Withdrawn
- 1980-06-20 FR FR8013781A patent/FR2459469A1/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7422678B2 (en) * | 2003-10-21 | 2008-09-09 | Teledyne Licensing, Llc | Evaluation of the corrosion inhibiting activity of a coating |
| US8016987B2 (en) | 2003-10-21 | 2011-09-13 | Teledyne Licensing, Llc | Evaluation of the corrosion inhibiting activity of a coating |
| DE102006028442A1 (en) * | 2006-06-21 | 2008-01-03 | Bayerische Motoren Werke Ag | Method for determining the damage to the electrocoating layer of a filler-free automotive paint by the action of light |
| CN105092461A (en) * | 2015-09-14 | 2015-11-25 | 北京科技大学 | Metal corrosion high-throughput characterization experimental apparatus based on image |
| CN105092461B (en) * | 2015-09-14 | 2018-01-02 | 北京科技大学 | A kind of metal erosion iron-enriched yeast experimental provision based on image |
| CN107024422A (en) * | 2016-01-29 | 2017-08-08 | 立邦涂料（中国）有限公司 | A kind of moisture resistance properties test device of aqueous woodware paint |
| RU2770844C1 (en) * | 2021-09-24 | 2022-04-22 | Публичное акционерное общество "Газпром" | Method for evaluating the protective efficiency of compositions inhibiting stress corrosion cracking in pipe steels |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1118991B (en) | 1986-03-03 |
| DE3022634A1 (en) | 1981-01-22 |
| GB2054865B (en) | 1983-09-07 |
| FR2459469A1 (en) | 1981-01-09 |
| IT7968325A0 (en) | 1979-06-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |