Fabrication of New Cemented Carbide Containing Diamond Coated with Nanometer‐Sized SiC Particles

Abstract

A simple process for depositing a coating of silicon carbide (SiC) crystallites ∼10 nm in size onto diamond particles has been developed. SiO powders react with diamond in a vacuum at 1350°C to form a uniform β‐SiC polycrystalline layer ∼60 nm thick. The SiC coating improves the oxidation resistance of the diamond. A cemented carbide material containing 20‐vol%‐SiC‐coated diamond particles was sintered to a relative density of 99.5% by pulsed‐electric‐current sintering. A Vickers hardness and indentation fracture toughness of 15 GPa and 16.3 MPa·m1/2, respectively, were obtained. This toughness is two times higher than that of cemented carbide containing no particles. The higher toughness is attributed to deflection and blockage of crack propagation by the diamond particles.

Growth Mechanism of Nanometer‐Sized SiC and Oxidation Resistance of SiC‐Coated Diamond Particles

“…The apparent activation energy was found to be 100 Ϯ 21 kJ/mol. Shimoo et al calculated the apparent activation energy for the formation of a SiC layer on a graphite plate based on reaction (7) and obtained 97 kJ/mol. 10 Both values for the activation energies are found to be in excellent agreement.…”

“…From these results, the SiC layer on diamond is considered to grow in a two-step process: (1) formation of a very thin SiC layer by the direct reaction between SiO(g) and diamond; (2) deposition of SiC on a thin SiC layer by reaction (7). Figure 10 shows the starting temperature of oxidation for SiC-coated diamond particles as a function of coating time at various temperatures.…”

“…We have developed a new process for coating SiC onto diamond particles by a very simple method using the reaction of SiO vapor with diamond. 6,7 Each diamond particle whose diameter was between 8 and 60 m was completely and uniformly coated with a ␤-SiC polycrystalline layer about 60 nm thick. The onset of oxidation of SiC-coated diamond was about 150°C higher than that for uncoated diamond.…”

SiC-coated carbon nanotubes and their application as reinforcements for cemented carbides

“…We have developed a new and simple process for coating diamond particles with SiC [15,16]. This coating is formed by a reaction of SiO vapor with the diamond surface.…”

Oxidation Resistance of Multiwalled Carbon Nanotubes Coated with Silicon Carbide

“…We have developed a new and simple process for coating diamond particles with SiC. [15][16][17] This coating is very simple, which is produced by a reaction of SiO vapor with the diamond surface. Each diamond particle is completely and uniformly coated with a nanometer-sized ␤-SiC polycrystalline layer.…”