Multi-Layer Coating for Optical Mold of Strengthening by Electroplating Ni-W and Electroless Plating Ni-Mo-P by Nonisothermal Method

Abstract

The development of optical mold coatings has become a key technology in precision optical components in recent years. Researchers are still seeking ideal electroforming materials capable of resisting higher temperature and improve the lifespan of optical mold. Examples of these materials include Ni-W, and Ni-Mo-P alloy plating, among others. However, the literature rarely mentions these alloys as protective coatings. This may be because coating stability, flatness, and strength cannot achieve the desired protective effects. This study develops a combination of two wet electrochemical processes to form a multi-layer coating on optical molds. This coating consists of Ni-W, and Ni-Mo-P alloys. The proposed treatment process attempts to enhance the mechanical strength of the mold and extend its lifespan. We first used electro-deposition to form a thick-film Ni-W coating, and then applied the electroless plating by nonisothermal deposition method (NITD) to create a Ni-Mo-P thin-film and form a multi-layer coating. We also measured the composition, hardness, and elastic modulus of the protective coating as a reference basis for the development of optical molds. The results of this study reveal the appropriate process parameters to provide the multilayer films with a high strength and flat surface. This article can serve as a reference for the development of optical mold coatings.

Recent trends in metal alloy electrolytic and electroless plating research: a review

“…Sarobol et al 87 analysed the finishes of Sn, Sn-Cu and Sn-Cu-Pb (various compositions) for hillock/whisker growth and found these to increase with certain textures that lead to Larson 98 formed an Ni-W and Ni-Mo-P multilayer coating on optical moulds using electrodeposition and electroless nonisothermal deposition respectively. The resultant flat, high strength materials are of interest for the development of precision optical components.…”

“…Thus, alloy deposits have been improved by composite plating, utilising the codeposition of dispersed particles, 23,33,36,56,114,134,136 pulsed current plating, 5,7,13,27,29,31,58,88,89,90,137 deposition within a magnetic field, 128,129 multilayer deposition 4,12,24,34,37,47,57,60,65,75,80,98 followed, usually, by a post-deposition heat treatment to produce the alloy, and deposition from ionic liquids 25,72,139 to expand possible systems, e.g. Zn-Sn coatings with considerably higher Zn contents than those possible from aqueous baths.…”