There are more hydrogen embrittlement testing methods as follows.

(4) Lawrence Hydrogen Detection Gage

This testing method was developed by a Boeing engineer Mr. Lawrence in cooperation with Mr. Takada for the purposes of plating bath management, and determining the effects and safety of aircraft landing gear cleaning solution and paint remover in relation to hydrogen embrittlement.

This method uses a metal cased vacuum tube as a probe to detect the hydrogen atom intrusion penetrating through the vacuum tube's metal case wall. The metal tube case (probe) is used as the cathode in the plating process. Hydrogen atoms generated during the plating process penetrates the coating layer and the steel case wall, and ionize when intrude into the vacuum tube. Here, an ionization gage is used to monitor and record the presence of hydrogen atoms.

Next, the plated probe is dried and placed into a 200 deg.C oven associated with the test equipment, and a baking process is performed. By the baking process, the hydrogen atoms occluded by the coating layer and the steel case wall diffusively migrates rapidly into the vacuum tube.

A barium getter is placed inside the vacuum tube to absorb and remove the migrated hydrogen at a constant rate. The vacuum level inside the probe can be interpreted as the change in hydrogen release rate. As the result, plating layer's hydrogen release characteristics can be determined.

As seen above, this testing method can measure the amount of hydrogen intrusion during the plating process, and hydrogen release characteristics by baking process.

[Fig.1] is a conceptual diagram of the testing probe. It explains how occluded hydrogen by the plating layer is measured.

1） Electrons (e) generated from the heated cathode are attracted to hydrogen molecules inside the vacuum tube. 2） The electrons accelerate when passing through the positively charged grid, and collide with the hydrogen molecules. H2+e→2H+Hydrogen molecules become ionized. 3） Ionized hydrogen H+ is attracted to #2 cathode and transforms into an electrical current, then read by a meter.