Abstract
Purpose - The main goal of the study was to improve current efficiency and to obtain thicker coatings via Al2O3 addition to the Cr (III) bath.Design/methodology/approach - Pure Cr and nanocomposite Cr-Al2O3 coatings were electrodeposited from trivalent chromium bath onto cathode copper substrates by conventional method. Dependence of current efficiency to current density, Al2O3 content and particle size was investigated.Findings - Current efficiency increased with Al2O3 amount and decreased with Al2O3 particle size. Maximum current efficiency was achieved at 25 A/dm2 for pure chromium and 30 A/dm2 for composite coatings. Al2O3 bath content, current density and stirring rate increased the coating Al2O3 weight percent, significantly. Addition of Al3+ bath composition inhibited nanoparticle agglomeration, increased film homogeneity. Cr-Al2O3 nanocomposites showed higher microhardness and better corrosion resistance than pure chromium layer.Originality/value - Cr (III) is not as toxic and as carcinogenic as Cr (VI) which is widely used for Cr electroplating these days. Low ccurrent efficiency and poor product quality are, however, major drawbacks of the former. This paper describes significant improvements obtainable by addition of Al2O3 nanoparticles to the trivalent chromium bath for increasing of the microhardness, the corrosion resistance and the current efficiency of the deposition.
Purpose - The main goal of the study was to improve current efficiency and to obtain thicker coatings via Al2O3 addition to the Cr (III) bath.Design/methodology/approach - Pure Cr and nanocomposite Cr-Al2O3 coatings were electrodeposited from trivalent chromium bath onto cathode copper substrates by conventional method. Dependence of current efficiency to current density, Al2O3 content and particle size was investigated.Findings - Current efficiency increased with Al2O3 amount and decreased with Al2O3 particle size. Maximum current efficiency was achieved at 25 A/dm2 for pure chromium and 30 A/dm2 for composite coatings. Al2O3 bath content, current density and stirring rate increased the coating Al2O3 weight percent, significantly. Addition of Al3+ bath composition inhibited nanoparticle agglomeration, increased film homogeneity. Cr-Al2O3 nanocomposites showed higher microhardness and better corrosion resistance than pure chromium layer.Originality/value - Cr (III) is not as toxic and as carcinogenic as Cr (VI) which is widely used for Cr electroplating these days. Low ccurrent efficiency and poor product quality are, however, major drawbacks of the former. This paper describes significant improvements obtainable by addition of Al2O3 nanoparticles to the trivalent chromium bath for increasing of the microhardness, the corrosion resistance and the current efficiency of the deposition.
