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Purpose The knowledge of the mechanical response of bones and their substitutes is pertinent to numerous medical problems. Understanding the effects of mechanical influence on the body is the first step toward developing innovative treatment and rehabilitation concepts for orthopedic disorders. Methods This was a comparative study of 5 synthetic scaffolds based on porous calcium phosphates and natural bones, with regard to their microstructural, chemical, and mechanical characterizations. The structural and chemical characterizations of the scaffolds were examined by means of X-ray diffraction, scanning electron microscopy, and X-ray spectroscopy analysis. The mechanical characterization of bones and bone graft biomaterials was carried out through compression tests using samples with noncomplex geometry. Results Analysis of the chemical composition, surface features, porosity, and compressive strength indicates that hydroxyapatite-based materials and trabecular bone have similar properties.

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Titanium and its alloys are becoming very promising materials in biomedicine due to their excellent properties. However, their poor tribological behavior characterized by high friction coefficient and severe adhesive wear is their main limitation. Surface modification technologies based on electrochemical and physical techniques have been successfully employed to improve the tribological performance and osseointegration of Titanium materials, ensuring an effective protection against both wear and corrosion. For instance, anodizing and plasma electrolytic oxidation (PEO) are two electrochemical techniques that allow the growth of an oxide film of high hardness and good adhesion. The formation of these oxide films in electrolytes with bioactive elements has been reported to enhance cell functionalities and improve the tribocorrosion performance of Titanium surfaces considerably. Similarly, physical vapor deposition (PVD) technologies such as cathodic arc evaporation (CAE) and magnetron sputtering (MS) are commonly used today for the growth of protective hard coatings on different Titanium components in the biomedical field. Diamond-like-carbon (DLC) and transition metal nitride (MeNx) and carbide (MeCx) protective films grown by PVD have proven to be excellent candidates to enhance Titanium and Titanium alloys performance and durability, owing to their excellent adhesion, high hardness, low friction coefficient and enhanced wear and corrosion resistance.

Lead containing bronzes are widely used as bearings, bushings and sliding plates. Lead is a heavy metal and known to be harmful to people and environment, but currently no feasible substitute material exists in many engineering applications. The ecological considerations in recent years have led to restrictions by the European Commission on the use of lead for example in the bearings used in cars (The Directive on the end-of-life of vehicles). However, due to the lack of substitutes for lead in many application areas, the ban has been given an exemption. The aim of the ECOBEARINGS project was to evaluate, whether any metallic or composite bearing material has similar tribological and mechanical properties as the currently used standard lead bronzes. In heavy machine engineering, lead bronze alloys containing up to 10-20 % of Pb are commonly used as sliding bearings such as thrust and journal bearings. In lead bronzes, lead has a function of a solid lubricant especially during the start of the operation of the bearing. Additionally, lead bronzes form a soft sliding surface where small contamination particles can be embedded in the material without causing an abrasive effect. A variety of different lead-free bearing solutions are already commercially available, but there are many applications where the emergency lubricating properties of lead cannot be substituted yet. It has been proposed that other solid lubricants such as graphite or bismuth could possibly have similar tribological characteristics as lead in bronze bearing materials. In this work, bronze alloys containing solid lubricants such as bismuth and graphite were produced by casting and spray forming. The alloys were characterized and tribologically tested in boundary lubricated and dry sliding conditions. The results were compared with the testing results of lead bronze. On the basis of the results, it was noted that different solid lubricants have very special tribological characteristics. This information can be used in the further development of ecologically sound bearing materials.