Rapid formation of TiC coating on diamond surface through thermal explosion reaction

Abstract

Objectives: Coating treatment on the surface of diamond particles is an important technique to effectively overcome the problem of difficult bonding between diamond and substrate, and the thermal explosion reaction is a common surface coating technique for diamond particles. However, this technology has disadvantages such as difficulty in separating diamonds from the product and a low proportion of diamonds, which increases its complexity and production costs, greatly limiting the promotion and application of this technology. This article aims to introduce polytetrafluoroethylene (PTFE) into thermal explosion reaction technology to form a coating mainly composed of TiC on the surface of diamond particles. It is expected to optimize the coating preparation process and promote the popularization and application of thermal explosion reaction technology in the field of diamond plating, so as to improve the wear resistance and service life of the diamond tools. Methods: Using two raw material systems, Ti/carbon black/diamond and Ti/carbon black/PTFE/diamond powders, the thermal explosion reaction of Ti/carbon black/diamond is induced by the chemical furnace method, and the intense chemical reaction between PTFE and titanium at low temperature ensures that the Ti/carbon black/PTFE/diamond system directly undergoes a thermal explosion reaction. At the same time, the TiC coating can be generated on the surface of diamond particles by adjusting the ratio of raw materials and triggering the thermal explosion reaction under high temperature conditions. The macroscopic morphology of diamond particles before and after coating is observed and compared by optical microscope to roughly infer the plating condition, and the phase compositions of the coating were analyzed by X-ray diffraction. Then the scanning electron microscope and the energy dispersive spectroscopy are used to observe the surface morphology of diamond particles, determine the elemental compositions, and infer the surface reaction state. Results: The thermal explosion reaction of both raw material systems can form a TiC coating on the surface of diamond. The main phase of the binder reaction product is TiC, and the main phases of the coating on the surface of diamond particles are TiC and Ti. But for the Ti/carbon black/diamond system, the chemical furnace method is needed to induce a thermal explosion reaction. When the diamond mass fraction in the raw material is 30% or lower, the TiC coating on the surface of the diamond particles is good. When a small amount of PTFE is introduced into the Ti/carbon black/diamond system, the reaction between Ti and PTFE releases a large amount of heat, which induces the thermal explosion reaction between Ti and carbon black and synthesizes TiC, and finally forms a TiC coating on the surface of diamond particles. In addition, the system does not need the chemical furnace method to detonate. When the diamond mass fraction in the raw material is less than or equal to 60%, the diamond particle surface coated with TiC coating is good. At the same time, appropriately reducing the content of carbon black in the raw materials can enable diamond to obtain a good TiC coating on its surface even when the mass fraction of diamond is 90% or higher. Conclusions: TiC coatings are prepared on the surface of diamond particles using thermal explosion reaction technology, and the important effects of raw material compositions and PTFE additives on the formation of diamond particles' surface coating are revealed. Adding an appropriate amount of PTFE can directly induce the thermal explosion reaction, which greatly promotes the increase of the proportion of diamond in the raw material, and effectively improves the formation quality of the coating. This can greatly save binder powder, thereby reducing production costs, while obtaining loose powder products that are easy to separate from diamonds. In addition, drawing on the work of this study, other carbide materials (such as SiC) can be analogously extended for coating on the surface of diamond particles, thereby promoting the promotion and the application of thermal explosion reactions in diamond coating.

Keywords

• ti-tic coating
• diamond
• thermal explosion
• ptfe