This volume introduces testing methods unique to industrial gold and gold alloy plating.

(1)Nitric acid aeration test (porosity test)

In this test, you will measure porosity of gold and gold alloy plating on a metal or nonmetal substrate by exposing the sample in the nitric acid vapor.

(1)Testing method

Prepare an appropriate size desiccator made of glass. Add a moderate amount of nitric acid into the bottom of the desiccator. Rinse a sample with ethanol or benzine and dry it. Place the sample on the porcelain plate of the desiccator and cover it with the lid. Let it stand for one hour at 23℃. Remove the sample from the desiccator. Then, rinse the sample with water and dry it.

(2)Assessment

Observe corrosion points generated from a defect, such as a pinhole on the test surface. Convert it to the number of corrosion points per 1 cm². The calculated value is the porosity.

(2)Color fastness test by heating

In this test, you will measure color fastness of gold and gold alloy plating on a metal or nonmetal substrate by heating it in a furnace. However, this test is not compatible with gold or gold alloy plating of less than 3 µm over copper undercoat or on a copper or copper alloy substrate. In addition, the testing method for partially plated products will be determined and agreed between the parties concerned.

(1)Testing method

Heat up the furnace to 120 to 130℃. Place a sample in it and wait for one minute. Then, remove it from the furnace and allow the sample to cool down.

(2)Assessment

Visually inspect the test surfaces and check for any discoloration.

(3)Hydrogen sulfide test (corrosion resistance test)

In this test, you will measure corrosion resistance of gold and gold alloy plating on a metal or nonmetal substrate by placing a sample in the hydrogen sulfide atmosphere.

(1)Testing method

Perform this test using a dedicated test machine for hydrogen sulfide corrosion. This machine is comprised of a temperature/humidity control equipment, a test piece support equipment, a hydrogen sulfide cylinder, a hydrogen sulfide quantitative dilution equipment, a concentration control equipment, and an exhaust treatment equipment. The testing conditions are as shown in the following [Table].

[Table] Major test conditions

(2)Assessment

Evaluate the degree of corrosion by the rating number standard drawings.