1 Scope

This standard specifies test methods for silver and silver alloy electrocoatings for engineering, decoration and protection against contamination by residual salts.

This standard applies to metal parts; Not applicable to composite parts, such as parts with both plastic and coated metal.

2 Principles

The part is boiled in water with known conductivity for a specified period of time and the increase in conductivity resulting from the precipitation of residual salts and other conductive impurities is measured.

ISO 4522-3-1988 – Methods of test for metallic coatings of silver and silver alloys – Part 3: Determination of residual salts

3 Reagents

Water: The conductivity is not more than 100µs/m at 20 ° C ±1 ° C.

4 Instruments

All glass instruments used shall be made of borosilicate glass, shall meet the cleanliness requirements specified in 5.2, and shall be kept separately for the purpose of this test.

4.1 Round bottom flask: the capacity is 250mL, and the water reflux condenser tube is installed.

4.2 Beaker: the size shall be suitable for the part under test, marked with 100mL scale, and equipped with appropriate devices to reduce excessive evaporation loss of water, such as cooling water cover.

4.3 Conductivity meter

ISO 4522-3-1988 – Methods of test for metallic coatings of silver and silver alloys – Part 3: Determination of residual salts

5 Test method

5.1 Sample

Take one or more parts fully covered by coated metal with a total surface area of approximately 30cm2 and test according to 5.3.1 or 5.3.2 according to their dimensions (see 5.3).

Be sure to avoid accidental contamination of the sample, in the inspection to bring clean glove corner out of the parts.

5.2 Inspection of instrument cleanliness

Before the assay, 100mL of water (see Chapter 3) was added to the test vessel (see 4.1 or 4.2) and then slowly boiled for 10min under the specified test conditions (see 5.3.1 and 5.3.2). The water was cooled to 20 ° C ±1 ° C and its conductivity was measured with a conductivity meter (see 4.3).

ISO 4522-3-1988 – Methods of test for metallic coatings of silver and silver alloys – Part 3: Determination of residual salts

If the measurement exceeded 100µS/m, it was redetermined with another 100mL of water. If the measured value exceeded 100µS/m again, the test was performed with a new container.

Qualified glass instruments shall be kept separately for this test.

5.3 Determination

5.3.1 Samples with a cross section width or diameter less than 15mm and a length less than 40mm.

After checking the cleanliness of the instrument (see 5.2), place the sample (see 5.1) into a round-bottomed flask and add 100mL of water (see Chapter 3). The conductivity of the water should have been determined quickly before the measurement. Completely immerse the test piece in water. Install a reflux condensing tube on the flask and slowly boil for 10min. Allow the water to cool to 20 ° C ±1 ° C and measure its conductivity with a conductivity meter (see 4.3). The value added of the conductivity was calculated as the measurement result.

5.3.2 Samples with cross section width or diameter greater than 15mm and length greater than 40mm.

Conduct the test as described in 5.3.1. Place the sample (see 5.1) into a beaker (see 4.2) that has been filled with water to 100mL scale. To prevent the loss of water by excessive evaporation during the measurement, a cooling water cover may be used and, if necessary, additional water (see Chapter 3) may be added to replace the evaporated water.

ISO 4522-3-1988 – Methods of test for metallic coatings of silver and silver alloys – Part 3: Determination of residual salts

6 Test Report

The test report shall at least include the following contents:

a) Reference to this Standard;

b) Name or number of test specimen;

) Total surface area of test sample,cm2; d) the name or model of the instrument used;

) Anomalies observed in the test; f) any instructions different from this method;

g) Test results and presentation methods;

h) Test date;

i) Name of operator and test laboratory.