Latest Addition to the WHW Portfolio: Hydrogen Permeation Measurement

At WHW Innovation and Technology Center (CIT), new methods and solutions are developed daily. The objective here is not only to provide customers with high-corrosion protection alongside galvanic coating processes, but also to supply test methods related to procedures such as protection against hydrogen embrittlement. To effectively prevent hydrogen embrittlement resulting from production, high-strength components must be stress-relieved today. This is not only a time-consuming process, but also a complex and expensive one in terms of energy intensity. With STRONGARD & OXIGARD, WHW Hillebrand Group has been offering recognized coating processes for several years that do not require stress-relieving and prevent the risk of hydrogen embrittlement. For this purpose, coating processes at WHW are closely monitored and all process stages critical to hydrogen embrittlement are controlled and approved step by step. This applies particularly to pickling and coating processes. The coating process is only subjected to processing after all tests have been performed, and products are delivered to our customers following final inspections. Everything from One Source To further increase efficiency in this effective process chain, we are making efforts to perform all necessary tests in-house. This means that all correct measuring instruments, relevant technical knowledge and appropriate measurement methods must be available within the company. One of these tests is the measurement of hydrogen permeation (permeability) according to DIN EN ISO 17081. This is suitable for determining the hydrogen hazard potential in the pickling process. A permeation cell is used in this test method. This consists of two half-cells separated by a membrane. The measurement principle can be described as follows: Hydrogen evolution occurs in the left half-cell, thus representing the "loading side." Hydrogen is produced either through galvanostatic processes (such as galvanic deposition) or chemical processes (pickling attack with hydrochloric acid). It is absorbed across the membrane and passes through it (migrates "from left to right" across the membrane due to concentration gradient) and emerges again on the "measurement side." The escaping hydrogen is immediately oxidized electrochemically in the right half-cell, during which one electron is produced per hydrogen atom. Thus, the hydrogen passing through can be recorded quantitatively via the measured current. In short, a current flowing over a specified period of time is measured. The result here is the charge in Coulombs, which is a measure of the hydrogen passing through and thus represents the hydrogen hazard potential. In the past, the hydrogen permeability test at WHW Hillebrand was performed by an external service provider. To also meet our "everything from one source" principle in the hydrogen embrittlement field, a project was launched at Hillebrand Chemicals in 2018 to integrate this measurement into the WHW Hillebrand Group portfolio. Objective: To independently perform hydrogen permeability measurement within our institution in the future.

Said and Done

Following development of the method, the measurement procedure was evaluated. For this purpose, a round-robin test was conducted with numerous independent test institutes, including the TU Darmstadt State Materials Testing Institute. Permeability measurement has been installed and integrated into the test laboratories of WHW Hillebrand Group and has since been successfully used to provide customers with the necessary process reliability and efficiency.     İzzet Aydın General Manager Hillebrand Chemicals Chemical Marketing Ltd. Co.