Periprosthetic joint infections (PJI) are a common reason for orthopedic revision surgeries. It has been shown that the silver surface modification of a titanium alloy (Ti–6Al–4V) by PMEDM (powder mixed electrical discharge machining) exhibits an antibacterial effect on Staphylococcus spp. adhesion. Whether the thickness of the silver-modified surface influences the adhesion and proliferation of bacteria as well as the ossification processes and in-vivo antibacterial capacity has not been investigated before. Therefore, the aim of this work is to investigate the antibacterial effect as well as the in vitro ossification process depending on the thickness of PMEDM silver modified surfaces.

TiAl6V4 wrought alloy is a standard material used for endoprostheses due to its ideal characteristics in terms of osseointegration. However, the insufficient wear and crevice corrosion resistance of TiAl6V4 are limiting factors that can cause clinical problems. Therefore, the objective of this study was to analyze and identify suitable phases and microstructural states of TiAl6V4 alloy with advantageous implant properties by thermal treatments. By varying the temperature and cooling rate, four heat treatment strategies were derived that produced different microstructural states that differed in morphology, arrangement and proportions of phases present. All TiAl6V4 modifications were characterized regarding their microstructure, mechanical, corrosive and tribological properties, as well as cell adhesion. The acicular, martensitic microstructure achieves a significant hardness increase by up to 63% and exhibits improved corrosion and wear resistance compared to the forged condition. Whereas the modified microstructures showed similar electrochemical properties in polarization tests using different electrolytes (PBS with H₂O₂ and HCl additives), selective α or β phase dissolution occurred under severe inflammatory crevice conditions after four weeks of exposure at 37 °C. The microstructurally selective corrosion processes resemble the damage patterns of retrieved Ti-based implants and provide a better understanding of clinically relevant in vivo crevice corrosion mechanisms. Furthermore, a microstructural effect on cell attachment was determined and is correlated to the size of the vanadium-rich β phase. These key findings highlight the relevance of an adapted processing of TiAl6V4 alloy to increase the longevity of implants.

Due to their excellent biocompatibility, favorable strength-to-weight ratio and mechanical properties, Ti-based alloys are most commonly used for long-term implants in the human body. Nevertheless, low wear resistance and increased degradation due to corrosion under critical in vivo conditions impair the service life of these implants. This fact opens the potential for optimization, which can be exploited by chemical alloying with Cr. This study investigates the effect of Cr alloying on the mechanical, tribological, corrosion properties and cytocompatibility of cp Ti and TiAl6V4 alloys. Argon-arc melting was used to cast binary and quaternary specimens of varying Cr content (0.1, 0.2, 0.4, 1, 2, 4, 8, 10, 15 and 20 m%). After homogenization (1100 °C, 30 min), microstructures were characterized by means of XRD and EBSD and correlated with mechanical properties using hardness and compression tests. At up to 2 m% Cr, a martensitic α' microstructure is formed. A Cr content of 4 m% reveals two phase α' + β alloys. Alloying with ≥8 m% Cr results in complete β phase, whereas the significantly reduced fracture compression indicates the formation of metastable ω phase for Cr content of 8-10 m%. Based on XPS analysis, a change in the composition of the passive layers by incorporation of Cr₂O₃ and CrO_x is verified. These modified passive layers result in a reduction in corrosion current densities under mimicked severe inflammatory conditions (PBS with HCl and H₂O₂). In addition, the tribological behavior is significantly improved by a reduced wear rate for binary Ti-2/4Cr and quaternary TiAlV-4/8Cr alloys. Cell viability is not inhibited by Cr alloying, but reduced calcification is observed for all Cr modified specimens. These findings highlight the tremendous potential of Ti alloying with Cr for improved implant properties, with the alloy range of 2-4 m% Cr being the most suitable.

The pyroelectric effect enables the generation of a strong electric field, which can lead to the emission and acceleration of electrons, ultimately resulting in x-ray production in combination with a metallic target. This study presents a systematic experimental investigation on the optimization of pyroelectric x-ray sources for material analysis. Lithium tantalate (LiTaO3) and lithium niobate (LiNbO3) crystals were examined to evaluate the influence of working pressure, crystal geometry, target material, and target arrangement on x-ray intensity and end point energy. Optimized parameters enhanced the x-ray output. By changing from a single crystal to a double crystal configuration, the measured end point energy is increased from 51 to 70 keV, representing a 37% enhancement in the end point energy. X-ray fluorescence (XRF) measurements of the steel samples were performed with an acquisition time of 600 s. Validation through XRF measurements confirmed faster acquisition for sufficient intensities and improved analytical precision. Upon introducing a second crystal, the spectra acquired during the 600 s cooling phase indicated that the Fe Kα intensity increased from 5000 to 10 000 counts. These results provide a foundation for the design of a compact, low power, and energy efficient pyroelectric x-ray source.