Carbonitride

Carbonitride refers to compounds that contain both carbon and nitrogen within their chemical formula. In solid-state chemistry, the term is often used for metal carbonitrides with the general formula M(C,N), where carbon and nitrogen occupy sites in a close-packed lattice. These materials commonly adopt a rock-salt-type structure with carbon and nitrogen sharing the non-metal sublattice, often distributed randomly.

Well-known examples include titanium carbonitride TiCN, hafnium carbonitride HfCN, zirconium carbonitride ZrCN, and silicon carbonitride SiCN. TiCN, in particular, is widely used as a hard coating and in cemented carbide tools, because of its high hardness, wear resistance, and thermal stability. Silicon carbonitride SiCN is studied as a high-temperature ceramic with strong bonding among Si, C, N, and sometimes O, offering good thermal stability and oxidation resistance.

Synthesis methods include carburization or nitridation of metal carbides or nitrides at high temperatures, chemical-vapor deposition (CVD), physical-vapor deposition (PVD), and polymer-derived routes for SiCN. The precise composition and structure can be tuned to balance hardness, toughness, and thermal properties, making carbonitrides versatile for engineering applications.

Properties of carbonitrides vary with composition but typically include high hardness, high melting points, and chemical inertness. These traits underpin their use in cutting tools, wear-resistant coatings, and advanced ceramics. In addition to metal-based carbonitrides, the field also explores carbon-rich nitrides and related solid solutions to tailor mechanical and thermal performance.