Characterization of Wet-Chemically Nanostructured Stainless Steel Surfaces
- PDF / 1,322,455 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 97 Downloads / 205 Views
Characterization of Wet-Chemically Nanostructured Stainless Steel Surfaces R. Buescher 1, H.P. Jennissen 2, M. Chatzinikolaidou2, A. Fischer 1 1 Materials Science and Engineering Department, 2 Institute of Physiological Chemistry, University of Essen, Germany Abstract
A novel surface modification process is presented, which creates a macroscopically smooth and a nanoscopically rough surface on an austenitic stainless steel. The chemical structure of the oxide layer is changed due to the acid treatment, whereas the thickness is not increased. An altered chromiumoxide content in the passive layer connected with a high bonding strength to the substrate material suggests the use of these wet chemically modified steels in biomedical applications. Introduction
The aim of modern implant research is to modify the topography and the chemistry of surfaces in order to gain a better integration in the human tissue. Many attempts make use of coating techniques, which create a bioactive surface with structures in the macro- and micrometer range. The effectiveness of various coatings is partly limited by their bonding strength to the substrate material. A surface modification on the other hand, which penetrates less than a µm is believed not to deteriorate the physical properties of the implant surface. In the present study, austenitic stainless steel was subjected to a novel wet chemical treatment, which modifies the chemical and topological structure of the surface. In order to characterize the surfaces properties, the structure and the penetrated rim zone were examined using mechanical, chemical and optical means. Experimental Details
In all experiments AISI 316L (Multi-Veredelung GmbH, Schliengen, Germany) was used as the starting material. The chemical composition is given in Table 1. From the variety of stainless steels, 316L was chosen due to its high strength and excellent corrosion resistance and therefore biotolerant behavior. Prior to the wet chemical treatment the machined samples were polished to obtain a homogenous surface. Since mechanical polishing always results in a very thin paracrystalline topmost layer, the samples were additionally electropolished. The smooth austenitic metals were incubated in a concentrated chromosulfuric acid (92% H2SO4, 1.3% CrO3, density 1.84 g/cm3) at 190-230°C for 30-90 min [1,2] and washed carefully before they were stored in methanol.
Y3.14.1
Table 1: Alloying elements [in weight-%] in the investigated austenitic stainless steel 316L AISI 316L
Short Name C Cr Mn X2CrNiMo18 15 3
Data Loading...
