Formation of diamond like carbon films on materials for medical application

Abstract

The aim of this experimental work is to identify how the surfaces of materials that are most often used in medical implants and prostheses, affect the properties of the deposited amorphous carbon films. The DLC films were formed on the stainless steel, aluminium, polyetheretherketone (PEEK) and polycaprolactone (PCL) surfaces by PECVD method using C 2 H 2 gas plasma and their properties was compared with the films deposited on silicon. The differences of the films properties were determined by a null-ellipsometry and Raman spectroscopy. It was found that the thicknesses of the carbon coatings deposited on metallic substrates are larger than on the silicon when the deposition conditions were the same. When the films are formed at high bias voltage the refractive index of the DLC films deposited on stainless steel are lower compared to the coatings on silicon but the extinction coefficients are higher. Raman spectra shows that sp 2 bonds concentration is higher in this case. When the ion energy is lowest (bias voltage -400 V), Raman spectroscopy shows that D peak isn't observed on the Si-deposited carbon coating, while the typical carbon amorphous coating is formed on the Al substrate. The thickness of amorphous carbon coatings deposited on the polymers depends on the bias voltage, and the optical properties depend on the type of polymer. The coatings deposited on PCL have a much higher refractive index than on PEEK.