Analysis of Biocompatible Metallic Materials used in Medicine

Abstract

The paper presents the results of the analysis of two biocompatible materials, Kirschner wires of different thicknesses. Kirschner wires (K-wires) are stainless steel pins used in surgery to fix bone fragments and to provide an anchor for skeletal traction. The K-wires are produced in different diameters. In the present work, a scanning electron microscopy and light microscopy were employed to document the microstructure of two K-wires with different thicknesses. Before observation, the wires were prepared by a standard metallographic procedure (grinding and polishing) followed by electrolytic etching. The chemical composition was determined by studying the wires using quantitative energy-dispersive X-ray spectrometry. It has been found that the chemical composition of the materials corresponds to Cr-Ni stainless steel. In the thick Kirschner wire (sample no. 1) a deformed microstructure after drawing was observed. Sample no. 2 (thin Kirschner wire), on the other hand, consisted of polyhedral austenitic grains, which were formed after recrystallization annealing. Furthermore, isolated microparticles were observed and assigned to titanium nitride. A Vickers hardness test was also performed on the samples. It has been found that the hardness of sample no. 1 was 428.8 HV 0.5. The average hardness of sample no. 2 was 213.4 HV 0.5. It can be concluded that recrystallization annealing decreases the hardness of the material. The K-wires with smaller diameter are thus easier to bend which facilitates their fixation in human body.