Heat Treatments

After deposition, NIPLATE® coatings are normally subjected to dehydrogenation or hardening heat treatments, according to the needs and specifications required.

Dehydrogenation

During pre-treatments and electroless nickel plating, a diffusion of atomic hydrogen occurs within the metal matrix in both the coating and the substrate. Due to this phenomenon, metals such as nickel, titanium, and high-strength steels in particular can undergo embrittlement, known as hydrogen embrittlement.

During electroless nickel plating, because deposition occurs without the input of an external electrical current, the amount of hydrogen that can diffuse is significantly lower than traditional electroplating coatings, such as chrome or nickel electroplating.

To prevent possible embrittlement, however, dehydrogenation is usually implemented, which typically consists of a heat treatment at 150–180°C for 4 hours.

Hardening

Electroless nickel plating treatments can be heat-treated to increase the coating's hardness. Coating hardening occurs through the formation of Ni3P aggregates within the coating that increase its hardness.

The hardening treatment can raise the hardness of the deposit from the initial 500–600 HV to values of 1000–1100 HV, depending on the temperatures and times used. As a rule, hardening heat treatments are carried out at 260–280°C for 8 hours or at 330–350°C for 4 hours, providing increasing surface hardness.