Tungsten coating by diffusion on diamond surfaces: process and characterization

Abstract Tungsten coating on the diamond surface can significantly enhance the thermal stability, corrosion resistance, and wear resistance of diamond, thereby stabilizing its performance. It can also improve the wettability of diamond with other matrix materials, enhance interfacial bonding, and optimize the properties of composite materials. In this study, high-purity tungsten powder was treated, and a self-made coating material was used to coat a nano-tungsten layer on the diamond surface via diffusion coating. The phase, microstructure, and microscopic defects of the tungsten-coated diamond were characterized and analyzed. The results show that continuous and dense nano-coatings can be formed on the diamond surface through diffusion coating. The main phases of the coatings are W, W₂C, and WC, with the absolute contents of W₂C and WC increasing as the coating time increases. The relationship between coating thickness and coating time transitions from linear to nonlinear with increasing time. The diamond {111} surface typically forms a dense, continuous structure with triangular etched pits, while the {100} surface usually presents a granular junction with square etched pits and a higher degree of etching. Additionally, random, irregular etched pits are observed on the diamond surface. These findings are of great significance for improving diamond properties and are expected to guide the development of diamond surface metallization and the diamond composite material system.