Use of scanning electrochemical microscopy as a predictive technique in a salt fog corrosion test

Patent metadata

Field	Value
Publication number	US-12332275-B2
Application number	US-202117905774-A
Country	US
Kind code	B2
Filing date	Mar 12, 2021
Priority date	Mar 12, 2020
Publication date	Jun 17, 2025
Grant date	Jun 17, 2025

Abstract

The use of the scanning electrochemical microscopy to predict the corrosion resistance results which would be obtained for a surface S1 having undergone an anticorrosion treatment if the surface S1 was subjected to a salt fog corrosion test, which use comprises an analysis of the surface S1 by scanning electrochemical microscopy.

First claim

What is claimed is:

1. A process for predicting corrosion resistance results which would be obtained for a surface S 1 having undergone an anticorrosion treatment if the surface S 1 was subjected to a salt fog corrosion test, the process comprising an analysis of the surface S 1 by scanning electrochemical microscopy, wherein the analysis comprises the following actions:
i) measuring, under previously selected operating conditions, a current at n1 different points of the surface S 1 by means of a scanning electrochemical microscopy probe to obtain n1 current values, n1 being an integer which is at least equal to 5;
ii) determining the percentage of the n1 current values obtained in step i) which are greater than or equal to a detection threshold D, any current value which is greater than or equal to D being considered as corresponding to a point on the surface S 1 likely to be corroded in the salt fog test; and
iii) determining, from the percentage obtained in step ii), the number N of corrosion points/unit area likely to be presented by the surface S 1 if it was subjected to the salt fog test and comparing the number of corrosion points/unit area thus obtained with the maximum number Nmax of corrosion points/unit area that the surface S 1 should have to successfully pass the salt fog test, whereby:
if N is less than the maximum number Nmax, then it is possible to predict that the surface S 1 will effectively successfully pass this test, while
if N is greater than the maximum number Nmax, then it is possible to predict that this surface will not successfully pass this test.

2. The process of claim 1 , wherein the analysis of the surface S 1 is carried out in feedback mode.

3. The process of claim 2 , wherein the analysis of the surface S 1 comprises a scanning of the surface S 1 with the scanning electrochemical microscopy probe and wherein a tip of the probe is maintained at a constant distance d from the surface S 1 during scanning the surface.

4. The process of claim 3 , wherein the tip of the probe follows, during scanning the surface S 1 , a trajectory comprising one or more rectilinear portions.

5. The process of claim 4 , wherein the tip of the probe follows, during scanning, a trajectory comprising several rectilinear portions which are parallel to each other.

6. The process of claim 3 ,
wherein the analysis of the surface S 1 comprises at least the steps consisting in:
a) selecting a point directly above the surface S 1 ;
b) bringing, at the point selected in step a), the tip of the probe to the distance d; and
c) scanning the surface S 1 with the probe from the point selected in step a) by maintaining the tip of the probe at the distance d and measuring a current at the probe during scanning,
wherein the analysis of the surface S 1 comprises positioning a scanning electrochemical microscopy probe at several points directly above the surface S 1 for obtaining such n1 current values, and
wherein a tip of the probe is located at a constant distance d from the surface S 1 at each positioning point.

7. The process of claim 6 , wherein the positioning points are randomly selected.

8. The process of claim 6 , wherein the analysis of the surface S 1 comprises at least the steps consisting in:
a) selecting the probe positioning points; and
b) bringing, for each positioning point, the tip of the probe to the distance d and measuring a current at the probe at each positioning point.

9. The process of claim 1 , which comprises an use of an electrolyte comprising a redox mediator in the reduced state.

10. The process of claim 9 , wherein the redox mediator is ferrocyanide, ferrocene, decamethylferrocene or ferrocene dimethanol.

Assignees

• Commissariat Energie Atomique
• Centre Nat Rech Scient

Inventors

• Charrier Gaëlle
• Doublet Aurélien
• Deniau Guy
• Cornut Renaud

Classifications

• G01Q10/065

  Feedback mechanisms, i.e. wherein the signal for driving the probe is modified by a signal coming from the probe itself · CPC title

• G01Q60/60 Primary

  SECM [Scanning Electro-Chemical Microscopy] or apparatus therefor, e.g. SECM probes · CPC title