What is Hydrogen Embrittlement?

Hydrogen embrittlement is the phenomenon where the interaction of hydrogen with other metals causes a reduction in the ductility and strength of the metal. Hydrogen atoms diffuse into the metal, disrupting the metal’s lattice structure. The change in the microstructure can be problematic, as the absorbed hydrogen can lead to fractures in the metal when a load is applied. The effects of hydrogen can vary based on the metal and metal properties. Metals with higher hardness levels and lower thicknesses are more susceptible to hydrogen embrittlement.

Hydrogen Embrittlement in Electroplating

Electroplating is depositing a metal onto another surface using an electric current in an aqueous electrolytic solution. The solution consists of various components such as metal salts, ions, chemicals, and water—the main component. As hydrogen is one of two elements in water’s makeup, hydrogen absorption can occur during most, if not all, of the steps in the electroplating process as hydrogen is present in the aqueous solutions.

Powered steps during the electroplating process increase the amount of hydrogen created compared to non-powered steps. Acid pickling, also known as the activation step, using an acid, is another step where an increase in hydrogen absorption typically occurs. The reaction between most acids and the metal creates free hydrogen ions as a byproduct which the metal can absorb during the process.

Mitigating Hydrogen in the Electroplating Process

Though eliminating the presence of hydrogen during the electroplating process is unfeasible, there are ways to mitigate the amount of hydrogen absorption in the standard electroplating process. After numerous research and trials, the engineering team at ProPlate? has established several methods to decrease the introduction of hydrogen during the electroplating process.

Limiting Powered Steps

Powered steps are often used for cleaning and activation of parts. Powered steps have proven to be more effective at ridding any debris and oil present on the component. Changing the steps to a non-powered step can help reduce the amount of hydrogen introduced to the component at that time in the process. Nevertheless, each process is unique and may require a powered cleaning and activation step. The component’s state upon arrival can determine if powered steps are necessary.

Limiting Acid Use

Submerging a metal in an acid creates a reaction producing free hydrogen atoms, which can then diffuse into the metal component. The time needed in acid baths is unique to each process, dependent on what is necessary to achieve adequate adhesion. Using a lower acid concentration, reduced acid time, or a combination of both can help limit the amount of hydrogen created.

Implementing Baking

Baking is a standard practiced method for components prone to hydrogen embrittlement. Metals with high hardness or essential mechanical properties, such as shape memory, typically have a post-bake included in the electroplating process. Nickel-Titanium Alloy, also known as Nitinol or NiTi, is a substrate with the essential mechanical properties of shape memory and is highly susceptible to hydrogen embrittlement. Standard electroplating processes for Nitinol include a final baking step at the end of the plating process.

There are several other proprietary methods ProPlate? implements to mitigate hydrogen absorption in the electroplating process and to prevent hydrogen embrittlement. The engineering team uses a combination of cleaning, activation, baking, and time management methods to develop the best process for each unique situation.

Ultimately, there is no solution to eliminate hydrogen embrittlement. However, there are precautions and steps to help avoid excess hydrogen absorption and lower the odds of hydrogen embrittlement. Implementing one or a combination of the above methods may help reduce hydrogen exposure to the component during the electroplating process.