Electrochemical Deposition and SEM Surface Morphology of Co and UHMWPE/Co Composite Layers

Abstract

The work aims at obtaining composite coatings in cobalt matrix with dispersed phase UHMWPE (ultra high molecular weight polyethylene) and at characterizing the surface morphology analyse by SEM, the thickness of the deposited layers and the microhardness of Co and Co/UHMWPE composite coatings. All coatings were obtained on stainless steel plates (304L). The electro-deposition of these metal and composite layers is a process consisting of inclusion of UHMWPE (ultra high molecular weight polyethylene) particles in the cobalt matrix during electroplating process. The dispersed particles were suspended in a sulphate cobalt plating electrolyte within the metal which electro-crystallizes and forms the metal matrix. By means of the potentiostat a number of five current densities were applied during deposition as follow: 23 mA/cm², 48 mA/cm², 72 mA/cm², 96 mA/cm² and 120 mA/cm². Keeping particles in suspension was ensured by magnetically stirring at a rotation speed of 300 rotations per minute. After processing the results, it has been noticed that with increasing current density there is an increase in the pure Co layer thickness too as well as in the UHMWPE/Co layers thickness. Adding particles UHMWPE particles in the electrolyte solution, the composite layers thickness is greater as compared with the thickness of pure Co layer obtained under the same electrodeposition conditions. UHMWPE was selected as surface modifier element, due to its high biocompatibility and excellent wear behaviour being used in many biomedical applications. Cobalt is already used in many cobalt alloys as biomedical implants as cobalt – chromium alloys. UHMWPE is also used as bio-polymer in many implants. The metal-matrix composites are materials in which the properties of a metallic host material are modified with addition of a second phase (ceramics, polymers, etc.) by electrodeposition process.