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A novel metal matrix composites (MMC) with Mg matrix reinforced with natural filler in the form of Didymosphenia geminata frustules (algae with distinctive siliceous shells) are presented in this work. Pulse plasma sintering (PPS) was used to manufacture Mg-based composites with 1, 5 and 10 vol.% ceramic filler. As a reference, pure Mg was sintered. The results show that the addition of 1 vol.% Didymosphenia geminata frustules to the Mg matrix increases its corrosion resistance by supporting passivation reactions, and do not affect the morphology of L929 fibroblasts. Addition of 5 vol.% the filler does not cause cytotoxic effects, but it supports microgalvanic reactions leading to the greater corrosion rate. Higher content than 5 vol.% the filler causes significant microgalvanic corrosion, as well as increases cytotoxicity due to the greater micro-galvanic effect of the composites containing 10 and 15 vol.% diatoms. The results of contact angle measurements show the hydrophilic character of the investigated materials, with slightly increase in numerical values with addition of amount of ceramic reinforcement. The addition of Didymosphenia geminata frustules causes changes in a thermo-elastic properties such as mean apparent value of coefficient of thermal expansion (CTE) and thermal conductivity (λ). The addition of siliceous reinforcement resulted in a linear decrease of CTE and reduction in thermal conductivity over the entire temperature range. With the increasing addition of Didymosphenia geminata frustules, an increase in strength with a decrease in compressive strain is observed. In all composites an increase in microhardness was attained. The results clearly indicate that filler in the form of Didymosphenia geminata frustules may significantly change the most important properties of pure Mg, indicating its wide potential in the application of Mg-based composites with a special focus on biomedical use. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has seen remarkable development in recent years due to relatively high efficiency of the process. Cold spraying (CS) is a particular method of AM, in which titanium and titanium alloy powders are used. CS is a very competitive technology enabling the deposition of coatings, repairing machine parts, and manufacturing new components. For specific applications, the surface of cold-sprayed materials may require further processing. This paper reports an attempt to employ laser surface treatment (LST) of cold-sprayed coatings on an aluminium alloy substrate. The influence of laser beam interaction time on the coatings' properties was analysed. The microstructure was investigated and observed employing scanning electron microscopy (SEM). To evaluate residual stress after CS and LST, the sin2ψ technique was used. Investigations were also performed on Vickers hardness, contact angle, and surface roughness. Significant changes in the surface morphology of the coatings and elevated residual stress levels dependent on the laser beam interaction time were observed. Increased Vickers hardness was recorded for titanium alloy Ti6Al4V. LST also led to increased surface hydrophilicity of the modified materials Ti and Ti6Al4V. [ABSTRACT FROM AUTHOR]

[Display omitted] • GO can functionalize inert zirconia surfaces by covalent immobilization. • GO nanofilm provides wettability and osteogenic character to zirconia implants. • GO coating on bioinert ceramics improves osteogenic differentiation of MSC. • Novel GO-film is full-covering, homogeneous, hydrophilic, and hydrolytically stable. This study aimed to join the proven osteogenic properties of graphene oxide (GO) with bioinert zirconia implants. The dip-coating technique allows achieving this goal by forming a thin, homogenous, hydrolytically, and mechanically stable GO film onto silanized ceramic-substrates. SEM, AFM, XPS, and contact angle measurements confirmed the presence, transparency, integrity, and homogenous covering character of the GO film. The GO film is hydrolytically stable since it remained intact after a soaking period of 24 days in double-distilled water (ddH 2 O) and phosphate buffered saline and resisted a ten-minute sonication treatment for in ddH 2 O. This strong hydrolytic stability is due to the silanization with 3-amino-propyl-diisopropylethoxy-silane (APDS) enhancing the anchoring of GO flakes onto zirconia surfaces. Besides, the GO film disinfectable in 70% ethanol. Subsequently, we assessed our immobilized GO film as cytocompatible for L929 mouse fibroblast and human mesenchymal stem cells and propitious for the osteogenic differentiation demonstrated by a two times upregulation of the osteogenic transcription factor RunX2. The active hydroxyl and carboxyl groups of the GO film open new perspectives for the functionalization of ceramic implants by immobilization of biological agents, such as growth factors or antibiotics, and thus enhance the osseointegration. [ABSTRACT FROM AUTHOR]