chemical stability

Diamond exhibits stable chemical properties and is resistant to non-oxidizing acids across various temperatures. However, it is not resistant to strong alkalis, oxyacids, and molten metals. For instance, when the {111} surface of diamond is corroded by strong oxidants such as potassium perchlorate (KCIO) and sodium perchlorate (NaCIO) at 380℃ for 181 hours, corrosion phenomena occur on the surface. It also dissolves in sodium nitrate molten salt at 430℃ and in molten metals.

oxidizing property

It begins to oxidize at 600℃ in oxygen and burns at 720℃. In air, it burns at 850℃. Residual oxygen in a low vacuum environment, such as 1kPa to 1Pa, can cause a dense black graphite film to form on the surface of diamond, which can be removed using hot perchloric acid or aqua regia. The formation temperature of this graphite film is above 600℃, but it is not a solid-state phase transition from diamond to graphite, but rather a transformation product of carbon monoxide or carbon dioxide. The graphitization reaction of diamond only begins when heated to 1500℃ in a clean inert gas, and the graphitization rate accelerates at 2100℃. Ion beam etching technology can achieve an etching rate of 2000Å/min.

Surface properties

Diamond is a non-polar mineral with a high oleophilicity on its surface, exhibiting a wetting contact angle ranging from 80° to 120°. Both the purity of the diamond itself and the cleanliness of its surface influence the performance of the diamond's surface.