Superhard cutting-tool materials refer to natural diamond, as well as synthetic diamond and cubic boron nitride (CBN) whose hardness and performance are comparable. Given the high cost of natural diamond, industrial applications of superhard cutting tools typically rely on synthetic polycrystalline diamond, polycrystalline cubic boron nitride, and their composite materials. Next, let’s take a closer look. Ultra-Hard Cutting Tool Solutions Let’s talk about its development and applications!

　　Diamond possesses extremely high hardness and wear resistance, with a microhardness reaching 10,000 HV, making it the hardest material among tool materials. In addition, it exhibits a low coefficient of friction, poor affinity with nonferrous metals, easy chip evacuation, and high thermal conductivity, which helps prevent built-up edge formation during cutting and results in excellent surface finish. However, copper, aluminum, and other nonferrous metals and their alloys, as well as ceramics, sintered carbides, and various fiber- and particle-reinforced composites, tend to undergo carbonization at temperatures between 700 and 800°C; therefore, diamond is not suitable for machining ferrous materials. This is because, at elevated temperatures, iron atoms readily react with carbon atoms to transform into a graphite structure. Furthermore, when used to machine nickel-based alloys, diamond tools also experience rapid wear.

　　 Ultra-Hard Cutting Tool Solutions Main Varieties and Applications

　　Currently, the main types of cemented carbide cutting tool materials that are either in use or undergoing trial include:

　　1. Natural and synthetically produced large single-crystal diamonds

　　Single-crystal diamond comes in two forms: natural diamond (ND) and synthetic diamond. To be used for manufacturing cutting tools, single-crystal diamond must consist of large grains, with a mass exceeding 0.1 g and a minimum diameter of less than 3 mm. ND is the hardest known mineral, boasting a microhardness of up to 10,000 HV, excellent wear resistance, and exceptionally sharp cutting edges characterized by low surface roughness, a low coefficient of friction, good resistance to adhesion, and high thermal conductivity. During machining, the superior hardness, wear resistance, corrosion resistance, and chemical stability of natural diamond tool inserts ensure exceptionally long tool life, sustained stable cutting performance, and reduced impact of tool wear on the workpiece; moreover, its high thermal conductivity helps lower cutting temperatures and minimize thermal deformation of the workpiece. This makes it an ideal solution for ultra-hard cutting tools.

　　2. Polycrystalline Diamond and Polycrystalline Diamond Composite Cutting Edges

　　PCD, also known as sintered polycrystalline diamond, is a polycrystalline material in which a large quantity of single-crystal diamond powder is consolidated under high temperature and high pressure with a metallic binder such as cobalt. Its hardness is slightly lower than that of natural single-crystal diamond; however, because it consists of randomly oriented diamond grains bonded together, it exhibits isotropic properties and lacks cleavage planes. Consequently, unlike large single-crystal diamonds, there is little variation in strength, hardness, and wear resistance across different crystal faces, and the material does not display the brittleness associated with the presence of cleavage planes.

　　3. CVD Diamond

　　CVD diamond is prepared under low-pressure conditions, unlike large single-crystal diamonds; PCD and PDC, by contrast, are synthesized under high-temperature and high-pressure conditions. CVD diamond comes in three forms: first, CVD diamond coatings deposited on suitable substrates (including diamond-like carbon, DLC, coatings); second, thick, unsupported CVD diamond films with a deposition thickness of 1 mm; and third, epitaxial growth of CVD diamond single-crystal or quasi-single-crystal films on diamond seed crystals. CVD diamond is pure diamond free of any metallic catalysts, giving it thermal stability comparable to that of natural diamond. Similar to high-pressure, high-temperature–synthesized polycrystalline diamond, the grains in CVD polycrystalline diamond are also randomly oriented, with no brittle cleavage planes and isotropic properties. Compared with PCD and PDC tools, CVD-coated tools offer advantages such as greater geometric complexity, lower cost, and multiple cutting edges per insert. However, superhard tool solutions based on CVD diamond also suffer from weak bonding between the diamond coating and the substrate, as well as a tendency for the coating at the cutting edge to delaminate during grinding operations. To date, the market for CVD diamond applications remains relatively small; compared with PDC, the main advantage of thick CVD diamond films is their superior thermal stability, while their drawbacks include low intergranular cohesion, high internal stresses, relatively high brittleness, and non-conductivity. In particular, the lack of electrical conductivity has hindered their use in electrical discharge machining (EDM) cutting and grinding processes. This technology is widely employed in the diamond-tool manufacturing industry, especially in the production and dressing of woodworking tools.

　　The above is the introduction to Ultra-Hard Cutting Tool Solutions For more information on its development and applications, please feel free to contact us at any time!