敦煌Chemical properties of diamond

First, hydrophobicity

Diamond is not wet to water, but tends to stick to oil. This hydrophobic lipophilic characteristic is determined by the nature of the non-polar bond of the diamond sp3 impurity. This characteristic not only suggests that people can use oil to extract diamond, but also in the manufacture of diamond abrasives, it is appropriate to choose organic compounds containing lipophilic genes as diamond wetting agents.

Second, chemical stability at room temperature

At room temperature, diamond is inert to all chemical reagents such as acid, alkali and salt, and aqua regia cannot chemically react with it. In the case of heating (below 1000 ° C), in addition to individual oxidants, it is not corroded by other chemical agents. Using the chemical stability of diamond, diamond can be purified with acid and base.

Third, oxidation at high temperatures (thermal stability)

At several hundred degrees of temperature, certain oxidants, such as KNO3 and perchlorate, can interact with diamond. Reagents such as NaNO3 corrode diamond in its molten state.

In pure oxygen, above 600°, the diamond begins to lose luster, and a black skin appears, which is called ember. Combustion starts at 700~800℃, and the reaction formula is C+O2→CO2.

In the air, the initial oxidation temperature of artificial diamond is 740~840 ° C, and some products can be oxidized at about 600 ° C. In the air, the initial combustion temperature is 850~1000℃. The thermal stability depends on the integrity of the diamond crystal.

4. Graphitization of diamond (thermal stability in non-oxygen media)