Development of polycrystalline Ni–P mold by heat treatment for glass microgroove forming

• Electroless plated amorphous nickel phosphorus (Ni–P) mold has been confirmed to be workable for microgroove forming at 330 °C, but its whole shape is subject to change when the molding temperature is at 380 °C.
• Polycrystalline Ni–P mold with a higher hardness was proposed to press glass at 380 °C.
• The method to reconstruct the flat surface of polycrystalline Ni–P mold is developed.
• Polycrystalline Ni–P mold has been confirmed to be capable of pressing glass at 380 °C without whole shape deformation.

This paper aims at developing electroless plated nickel phosphorus (Ni–P) as a mold material for glass microgroove forming by glass molding press (GMP) method. A kind of Ni–P with excellent machinability is investigated for the mold fabrication. The mechanical characteristics and the performance of amorphous nickel phosphorus (a-Ni–P) plating layer were experimentally tested. In order to increase the shape consistency and prolong the service life of the mold, polycrystalline nickel phosphorus (c-Ni–P) was developed by heat treatment. With the increase of the hardness after crystallization, the plating layer shape changes due to the heat treatment, and the strategy to deal with the deformation and the techniques to produce c-Ni–P mold are generalized. Finally, the performance of c-Ni–P mold was experimentally tested, which confirmed that c-Ni–P is a workable mold material for glass microgroove forming.