Production of Diamond-Like Carbon (DLC) Coatings by the Liquid-Phase Electrical Discharge

Carbon usually exists in several forms; graphite, diamond, and the new form of fullerenes. All three of these forms are crystalline in structure but have varying properties based on the bonding order of the carbon atoms. Diamond-like carbon (DLC), on the other hand, is amorphous in structure, containing both sp2 and sp3 bonded carbon. As such, DLC has both diamond-like and graphitic properties. Today, the most prevalent applications of DLC are those exploiting the ability of this material to reduce abrasive wear of various metals, such as stainless steel and alumina. In this work, for the first time, DLC film formation was tested using pulsed electrical discharge in four different organic liquids: acetonitrile, dimethyl sulfoxide, methanol and acetone. Raman spectra confirmed the presence of graphite and crystalline carbon on a high-voltage electrode when the discharge took place in liquid acetonitrile and dimethyl sulfoxide but not in methanol or acetone. In addition, the formation of plasma in a medium other than water was an opportunity to study the chemical and physical properties of the discharge. It was found that the boiling point of the liquid is a major factor determining the discharge initiation.