STUDY OF ELECTROCHEMICAL DEPOSITION PROCESS OF CHROMIUM IN THE PRESENCE OF COMPOSITE DIAMOND-CONTAINING COMPOUND

Abstract

The purpose of the study is to develop a method for producing a high-quality electrochemical chromium coating using a new type of diamond-containing additive, which has significant advantages over traditionally used detonation nanodiamonds (DNDs) in the form of aqueous suspensions. As an additive, a powdered composite diamond-containing compound was developed and used, consisting of detonation nanodiamond (DND), alkaline agent (NaHCO₃) and acid agent (citric acid). The composition contains 62.5 wt. % of DND. A standard chromium electrolyte was used: CrO₃ - 250 g / l, H₂SO₄ - 2.5 g / l, DND – 0.1 to 5 g / l, traditional methodologies and the algorithm of the experiment was applied.

The scope of the study is limited to the creation and application of a specific, easy-to-use and prepare DND composition. Modified DND (MDND) can be added to the standard chromium electrolyte directly or in the form of a freshly prepared aqueous suspension, it is environmentally friendly. A significant increase in the current yield of chromium by ~ 5% was achieved.

The originality of the work lies in combining the “inert” nanodiamond and active alkaline and acid components in the diamond-containing composition, which work only when introduced into the aquatic environment and provide the necessary disaggregation and stability of DND suspensions. An increase in microhardness of wear-resistant chromium coating by 1.3 times (up to 9.6 GPa) and hard chromium coating by 1.6 times (up to 13.6 GPa) were achieved. The wear resistance of the resulting coatings increased by 2 times. Concentration (based on pure DND) from 1 to 5 g / l in the electrolyte.