GB/T 24488-2021 English PDF (GBT24488-2021)

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GB/T 24488-2021: Test method for electrochemical properties of magnesium alloys sacrificial anode
GB/T 24488-2021
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.99
CCS H 21
Replace GB/T 24488-2009
Test method for electrochemical properties of magnesium
alloys sacrificial anode
ISSUED ON: AUGUST 20, 2021
IMPLEMENTED ON: MARCH 1, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and Definitions ... 6
4 Principle of the method ... 7
5 Test conditions ... 7
6 Reagents ... 8
7 Instruments and equipment ... 8
8 Samples ... 10
9 Test steps ... 13
10 Experimental data processing ... 15
11 Precision ... 17
12 Test report... 17
Test method for electrochemical properties of magnesium
alloys sacrificial anode
Warning -- This document does not indicate all possible safety issues. The user of
this document shall take appropriate safety and health measures and formulate
corresponding rules and regulations.
1 Scope
This document specifies the electrochemical performance test method for magnesium
alloy sacrificial anode samples when working in saturated calcium sulfate and
magnesium hydroxide medium.
This document applies to the electrochemical performance test for magnesium alloy
sacrificial anodes (hereinafter referred to as buried anodes) when the saturated calcium
sulfate and the magnesium hydroxide testing electrolyte are used for serving as the
padding for the buried anode. This document can also be used as a reference for the
electrochemical performance test of the magnesium alloy sacrificial anode for a water
heater (hereinafter referred to as water-heater anode) used in freshwater.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 6682 Water for analytical laboratory use—Specification and test methods
GB/T 8170 Rules of rounding off for numerical values and expression and judgment
of limiting values
GB/T 17731 Magnesium alloy sacrificial anode
3 Terms and Definitions
The terms and definitions defined in GB/T 17731 and the following apply to this
document.
3.1 Closed circuit potential
In the electrolyte, the cathode is connected to the sacrificial anode; the potential of the
sacrificial anode that is relative to the reference electrode, when the current is passing
through.
3.2 Open circuit potential
In the electrolyte, the cathode is connected to the sacrificial anode; the potential of the
sacrificial anode that is relative to the reference electrode, after the current is
disconnected for 1 h.
3.3 Practical current capacity
The actually measured amount of electricity produced by consuming a unit mass of
sacrificial anode.
[Source: GB/T 17731-2015, 3.1]
3.4 Theoretical current capacity
The amount of electricity produced by consuming a unit mass of sacrificial anode,
which is calculated according to Faraday’s law.
[Source: GB/T 17731-2015, 3.2]
3.5 Current efficiency
The percentages of practical current capacity and theoretical current capacity.
4 Principle of the method
Make the constant DC current flow through a series-connected test cell consisting of a
pre-weighed magnesium alloy anode sample, a steel cathode test crucible, and the
electrolyte for 14 d. Measure the oxidation potential of the sample several times during
the test; measure the oxidation potential of the sample after the test ends and the current
is disconnected for 1 h; measure the total amount of electricity flowing through the
battery. After the test, wash and weigh each sample, and calculate the amount of
electricity obtained from the loss of a unit mass of the sample.
5 Test conditions
During the test, the temperature of the electrolyte shall be kept within the range of
22 °C±5 °C.
9 Test steps
9.1 Test preparation
9.1.1 When using a copper coulombmeter (as shown in Figure 2), use fine abrasives (00
# or finer) to grind the coulombmeter’s cathode copper wire; then, put it in an oven, dry
it at 105 °C for 15 minutes, and cool it to room temperature; weigh it, and the weight
shall be accurate to 0.1 mg. The anode copper sheet shall be cleaned before being put
in the coulombmeter’s solution, and the purity of copper wire and copper sheet shall
not be less than 99.9%.
9.1.2 Wash the anode sample with water and acetone in turn; then, put it in an oven, dry
it at 105 °C for 30 min, and cool it to room temperature; weigh it, and the weight shall
be accurate to 0.1 mg. After the sample is cleaned with acetone, in order to avoid
contamination of the sample, the sample shall be handled with gloves.
9.1.3 Buried anode sample: Use insulating tape to wrap the surface between 100 mm
and 139 mm from the immersed end face of the sample, so that the immersion area of
the sample is 41.2 cm2.
9.1.4 Sample of the extruded magnesium anode of the water heater: Seal the immersed
end face and the surface 10 mm away from it with insulating materials; wrap the surface
between 113.2 mm and 142 mm from the immersed end face of the sample with
insulating tape, so that the immersed area of the sample is 41.2 cm2.
9.1.5 Sample of the cast magnesium anode of the water heater: Process it according to
the method of “9.1.3 Buried anode sample”.
9.1.6 Brush the cathode test crucible with soft plastic. If the inner surface of the cathode
test crucible is completely covered by a high-resistance coating, and the required
current cannot be obtained, the high-resistance coating on the surface shall be removed
by sandblasting, wire brushing, or scraping.
9.2 Sample determination
9.2.1 Add the electrolyte to the cathode test crucible until the solution is about 15 mm
away from the top.
9.2.2 Insert the sample into the rubber stopper and then put it in the cathode test crucible.
9.2.3 Put the anode copper sheet and cathode copper wire in the coulombmeter’s
solution, and the length of the copper wire immersed shall be 10 mm~50 mm.
9.2.4 The schematic diagram of the complete test circuit is shown in Figure 6. 0.75 mm2
insulated stranded copper wire is used in the circuit. Each end of each wire is connected
method of the closed-circuit potential in 9.2.6.
9.2.8 After the test is completed, first remove the wires on the sample; then, take the
sample out of the electrolyte, and remove the rubber stopper; finally, remove the tape
on the sample.
9.2.9 Put an untested sample in the cleaning solution preheated to 60 °C~80 °C, leave
it in the solution for 10 minutes (or put it in the cleaning solution at room temperature
for 30 minutes); then, wash it with tap water, and finally dry it in a 105 °C oven for 30
min; if the mass loss of the sample is greater than 5 mg, pour out the cleaning solution;
if the mass loss of the sample is less than 5 mg, place the tested sample and the untested
sample together in the cleaning solution at 60 °C~80 °C for 10 min or put them in room
temperature cleaning solution for 30 min; then, wash them with tap water, and dry them
in a 105 °C oven for 3 h; if the mass loss of the untested sample is more than 5 mg,
repeat the steps 9.2.1~9.2.9.
9.2.10 When using a copper coulombmeter, the cathode copper wire on the
coulombmeter shall be removed, then washed with tap water...