Why stainless steel diaphragms are gold plated when measuring hydrogen in pressure transmitters?

1.Hydrogen Permeability and Its Effects

Hydrogen (H₂) is a very small molecule that can easily permeate solid materials, including metals like stainless steel. This causes two main issues:

-Hydrogen Embrittlement: Hydrogen atoms diffuse into the steel’s lattice, making it brittle and more prone to fracture under stress.

-Measurement Errors: Hydrogen penetration into the diaphragm affects the strain properties, leading to inaccurate measurements in pressure transmitters.

2.Gold Plating to Prevent Hydrogen Penetration

Gold is used to prevent hydrogen from penetrating stainless steel due to its properties:

-Low Permeability: Gold's denser atomic structure significantly reduces hydrogen diffusion.

-Corrosion Resistance: Gold does not react with hydrogen, maintaining its stability.

-Prevention of Embrittlement: Gold blocks hydrogen entry, preventing embrittlement in the stainless steel substrate.

3.Gold Plating Mechanism

A gold-plated stainless steel diaphragm acts as a physical barrier, preventing hydrogen from entering the material. This preserves the diaphragm’s mechanical strength and ensures stable, accurate readings from pressure transmitters.

4.Application in Industry

In industries like chemical and energy sectors, hydrogen is common. Without gold plating, stainless steel diaphragms fail over time when exposed to hydrogen. Gold-plated diaphragms extend the lifespan and reliability of pressure transmitters in hydrogen-rich environments.

5.Conclusion

Gold plating is essential for stainless steel diaphragms in hydrogen measurement applications. It forms a barrier that prevents hydrogen permeation, ensuring long-term equipment stability and accurate measurements.