Abstract: Objectives:
In order to optimize the performance of diamond and improve its utilization rate, this paper carried out metallization treatment on the surface of diamond and successfully achieved reliable control of coating thickness.

Methods:
This article uses a high-temperature molten salt plating method to uniformly coat the surface of diamond with 1-5 μ m titanium nickel, titanium molybdenum, titanium tungsten, and titanium cobalt bimetallic coatings. In order to deeply analyze the composition and morphology characteristics of bimetallic coatings on diamond surfaces, advanced characterization techniques such as XRD (X-ray diffraction), EDS (energy dispersive spectroscopy), XPS (X-ray photoelectron spectroscopy) were used to comprehensively characterize and analyze the composition of the coatings. At the same time, SEM (scanning electron microscopy) was used to observe the morphology of the coatings in detail. In addition, Nano Measure and AFM (atomic force microscopy) were used to measure the thickness and surface roughness of four different diamond coatings.

Results:
The experimental data results show that under the conditions of coating temperature of 1000 ℃ and insulation time of 60 minutes, all four diamond bimetallic coatings can form titanium carbide coatings and titanium coatings, and stable compounds are formed between nickel, molybdenum, tungsten, cobalt elements and titanium. The presence of these compounds in the diamond coating forms stable chemical bonding energy, ensuring the stability and reliability of the coating. The titanium nickel, titanium molybdenum, titanium tungsten, and titanium cobalt bimetallic coatings on the surface of diamond particles are uniform and dense. The coating thickness of the four diamond bimetallic coatings is strictly controlled within the range of 1-5 μ m. Effective control of diamond coating thickness provides the possibility for achieving efficient application of diamond tools in various environments. Further research has found that among the four diamond bimetallic coatings, the roughness of the diamond (100) crystal plane is generally greater than that of its (111) crystal plane. Specifically, among the four types of diamond bimetallic coatings, the diamond titanium cobalt bimetallic coating exhibits the highest surface roughness and thinnest coating thickness, which is closely related to the differences in affinity and mismatch between metal nickel powder, molybdenum powder, tungsten powder, cobalt powder, diamond, and titanium powder during the salt bath plating process. Due to the high affinity between titanium powder and diamond, it preferentially reacts with diamond to generate TiC. This type of carbide not only improves the wettability of nickel, molybdenum, tungsten, cobalt and diamond, but also enhances the bonding force between diamond and metal matrix, making the bimetallic coating on the surface of diamond more uniform and dense.

Conclusions:
The metallization coating treatment on the surface of diamond not only provides effective protection for diamond, but also significantly increases the oxidation temperature of diamond. Meanwhile, due to the controllability of diamond coating thickness, this technology is expected to further expand the application range of diamond tools and meet more complex and demanding working environment requirements. This research achievement is of great significance for improving the performance and service life of diamond tools, and provides strong technical support for the widespread application of diamond materials.