Volume 14 (2014): Issue 3 (October 2014)

Currently, on prosthesis in cardiac blood vessels and heart valves are used materials of animal or synthetic origin. For animal materials include, among others pericardial sac in which is the heart. Materials such as this (natural) are characterized by a remarkable biocompatibility within the human body, but their main disadvantage is the relatively low durability. In turn, synthetic materials, which include the austenitic chromium-nickel-molybdenum steels, alloys with a shape memory (nickel-titanium), or polymeric materials, such as lactic acid, are characterized by high stability in an environment of bodily fluids, wherein the insufficiently high biocompatibility with the organism human requires from patients using after implantation, anticoagulants which prevent anti-platelet deposition on the surface of the prosthesis. The present work is a review of biomaterials using in implantology and implants using in cardiac and vascular surgery.

The paper deals with the measurements of selected parameters during grinding process of aerospace industry alloy. Grinding is one of the most important methods of shaping machine elements. As a result of grinding with high dimensional and shape accuracy as well as with the expected parameters describing the state of the surface layer (SL) should be obtained. Grinding difficult to machine materials used in the aerospace industry is an issue currently being examined by various research centres. An excellent example is the analysis of the grinding process of titanium alloys, as these materials have very poor machinability due to the tendency to adherence to abrasive materials, low thermal conductivity, high strength and compliance at elevated temperatures, which may adversely impact on the quality of SL. A number of factors influence on shaping SL. Worth mentioning are mechanical and thermal phenomena, as well as the type of cutting fluid and abrasive materials

The paper presents an investigation of the bainite morphology in two experimental Mo-Cr and Mo-Cr-V-Ti steels using TEM, high speed dilatometry backed by thermodynamic analysis. The microstructure was investigated using metallography and TEM method. After austenitisation at 1200^oC followed by bainitic reaction in upper and lower temperatures of isothetmal transformation the bainite was in the form of classical sheaves. The amont, distribution and morphology of retained austenite and bainitic ferrite depend on prior austenitisation and isothermal transformation temperatures within the bainitic range.

This work presents the nanoindentation results of two newly developed titanium alloy biomaterials, TNZ and Ti2448, after different surface treatments. The investigations were performed on the samples, AR – as received, MP – after abrasive polishing, EP – after a standard electropolshing, and MEP – after magnetoelectropolishing. The electropolishing processes, both EP and MEP, were conducted in the same proprietary electrolyte based on concentrated sulfuric acid. The mechanical properties of the titanium alloys biomaterials demonstrated an evident dependence on the surface treatment method, with MEP samples revealing extremely different behaviour and mechanical properties. Such a different mechanical behaviour may mean completely different composition and thickness of the surface film formed on the studied samples after MEP

The paper presents a study of the process of grinding stainless steels with different carbon contents. Verified the size and scope of the energy which is introduced in the surface layers for different types of abrasive grains and binders. The influence of parameters in plunge grinding process was considered in studies. The energy ratio was used for this purpose, which was calculated by multiplying energy and time of grinding wheel contact with the workpiece. To investigate influence of different carbon content on the level of energy density generated during grinding process special parameter B_p have been evaluated. The grinding tests were conducted in dry grinding technique.

The key requirement for the modern endoprosthesis is high durability of the friction components, which results in long and trouble-free operation in the human body. The durability of currently used endoprosthesis is often limited by tribological wear processes of friction components (e.g. between the head and the acetabular component in a hip joint endoprosthesis) [8, 19, 23, 24]. In order to compare the tribological wear, tribological tests were carried out by means of tribometer on friction pairs of the following composition: implantation steel 316 LVM/PE-UHMW and titanium alloy Ti13Nb13Zr/PE-UHMW. Determining of the friction coefficient, measured profiles of surface roughness and microscopic observation allowed to evaluate the abrasive wear of the tested biomaterials.