Silver-silver sulfide reference electrode

Patent metadata

Field	Value
Publication number	US-2022091064-A1
Application number	US-202117461771-A
Country	US
Kind code	A1
Filing date	Aug 30, 2021
Priority date	Aug 28, 2020
Publication date	Mar 24, 2022
Grant date	—

Abstract

This present disclosure is directed to a silver metal wire coated with silver sulfide reference electrode, the preparation via anodization of a silver metal wire in a sodium and/or potassium sulfide solution and use thereof, including test methods to measure corrosion in test articles such as metal pipes. The reference electrode exhibits good stability characteristics, including stability under high temperature conditions.

First claim

We claim:

1 . A reference electrode apparatus, the apparatus comprising:
a silver wire; and a silver sulfide coating formed on the wire to produce a silver sulfide coated silver wire wherein said silver sulfide wire is prepared by anodizing silver wire in an aqueous sodium sulfide solution.

2 . A method of making a reference electrode apparatus, said method comprising
putting a silver wire Ag(0) in a solution of sodium sulfide (Na 2 S) or sodium sulfide (K 2 S); forming Ag 2 S on said Ag wire by anodizing Ag wire to generate Ag(+1) which in the presence of sodium sulfide or potassium sulfide reacts to form and deposit Ag 2 S on the silver wire to form a silver/silver-sulfide reference electrode (SSRE).

3 . A method of measuring corrosion rate of a pipe and/or or pipe thickness loss, said method
a. using a device comprising a reference electrode of claim 1 to control voltage between device under test (DUT) and the silver/silver-sulfide reference electrode (SSRE) so the potential at the DUT versus the SSRE is known, and then measure electrochemical current through the DUT versus a counter electrode as a function of the potential of the DUT versus SSRE data; b. applying a means for calculating metal corrosion current that converts to corrosion rate to obtain mass loss from said pipe (in grams/year) and/or pipe thickness loss (in mm/year); wherein said method optionally comprises applying a means for controlling potential, recording mass loss data and/or displaying said data.

4 . The method of claim 3 , wherein said method further comprises applying a means of controlling the potential of the metal of said pipe versus said reference electrode and recording the corrosion current on said metal.

5 . The apparatus of claim 1 , wherein said apparatus shows a stable potential.

6 . The method according to claim 1 , said method comprising
a) preparing an aqueous sodium sulfide solution; b) submerging one or more silver metal wire strips into said sodium sulfide solution; c) connecting the silver metal wire strip to a power supply (using e.g., connection wires), thereby forming a cell; d) running a current through the cell at between about two and about five volts for about 5 to about 10 minutes to coat the silver metal wire strip with silver sulfide, thereby forming the reference electrode apparatus as disclosed herein; e) removing the silver/silver-sulfide electrode from positive connection of the power supply; f) rinsing and then drying the silver/silver-sulfide electrode; g) optionally, submerging a silver sulfide coated end of the electrode into a solution of silver sulfide.

7 . The apparatus of claim 1 , wherein said silver sulfide coated silver wire is coated with titania or magnesia to obtain a “tubeless” reference electrode.

8 . The apparatus of claim 1 , wherein said apparatus is prepared by a method comprising
a) preparing an aqueous sodium sulfide solution; b) submerging one or more silver metal wire strips into said sodium sulfide solution; c) connecting the silver metal wire strip to a power supply (using e.g., connection wires), thereby forming a cell; d) running a current through the cell at between about two and about five volts for about 5 to about 10 minutes to coat the silver metal wire strip with silver sulfide, thereby forming the reference electrode apparatus as disclosed herein; e) removing the silver/silver-sulfide electrode from positive connection of the power supply; f) rinsing and then drying the silver/silver-sulfide electrode; and g) submerging a silver sulfide coated end of the electrode into a solution of silver sulfide.

9 . The apparatus of claim 1 , wherein said apparatus is prepared by a method comprising
putting a silver wire Ag(0) in a solution of sodium sulfide (Na 2 S) or sodium sulfide (K 2 S); forming Ag 2 S on said Ag wire by anodizing Ag wire to generate Ag(+1) which in the presence of Na 2 S (or K 2 S) reacts to form and deposit Ag 2 S on the silver wire to form a silver/silver-sulfide reference electrode (SSRE).

10 . The method of claim 3 , said means for calculating metal corrosion current (e.g. in Amp/s) is a computer, an ASIC, a tablet, or smartphone.

11 . The method of claim 4 , wherein said a means for calculating metal corrosion current that converts to corrosion rate to obtain mass loss is a computer, an ASIC, a tablet, or smartphone.

12 . The method of claim 4 , wherein said means of controlling the potential of the metal of said pipe versus said reference electrode and recording the corrosion current on said metal is potentiostat or a Keithly 2400 Source-meter, which is optionally programmed with Labview software.

13 . A sensor apparatus comprising said a reference electrode apparatus according to claim 1 , wherein said reference electrode apparatus generates output values which are optionally transformed into one or more kinetic parameters of a material.

14 . The sensor apparatus of claim 14 , wherein the sensor output values are generated on board the reference electrode apparatus, processed and transformed to one or more kinetic parameters of said material via a data logger/potentiostat/other sensor reading/computing device that is hard-wired or wirelessly connected to the sensor, whereupon the sensor data presented to the user using a local sensor mounted or remote wireless visual display.

15 . The sensor apparatus of claim 14 , wherein the sensor output values are generated on board the reference electrode apparatus, stored in local sensor mounted memory, processed and transformed to one or more kinetic parameters of said material via an onboard sensor mounted computer, and presented to the user using a local, sensor mounted visual display.

16 . The sensor apparatus of claim 14 , wherein an array of said sensor output values are transmitted to a central server, either in a local area network or cloud based, where the sensor output data is stored in server memory, automatically transformed to desired kinetic parameters of materials via a server computer and presented to the user using a visual display.

17 . The sensor apparatus of claim 14 , wherein said material is metal in a pipe.

18 . The sensor apparatus of claim 14 , wherein said apparatus provides either hard-wired or wireless delivery of sensor output values to a separate local area network or cloud-based computing system whereupon the sensor data presented to the user using a hard-wired or remote wireless visual display.

19 . The sensor apparatus of claim 14 , wherein the kinetic parameters of said material is chosen from corrosion potential and corrosion rate of a metal in corrosive medium.

Assignees

• Univ Arizona

Inventors

• Gervasio Dominic Francis
• Danton Kalin
• Kim Gil-Pyo
• Sasaran Vlad Alex
• Mcevoy Nicholas Michael
• Gary Alexis

Classifications

• C25D11/34

  of metals or alloys not provided for in groups C25D11/04 - C25D11/32 · CPC title

• G01B7/06

  for measuring thickness {(measuring during the manufacture of coatings C23C14/54)} · CPC title

• G01N27/301 Primary

  Reference electrodes · CPC title

• G01N27/48

  using polarography, i.e. measuring changes in current under a slowly-varying voltage · CPC title

• G01N17/02

  Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement · CPC title