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•Friction stir process fabricates a rough and nanosized composite layer on the surface of Tit-6Al-4V alloy.•The composite layer is composed of mainly Ti-6Al-4V and TiO2.•The surface ...microhardness of composites is greatly improved.•The alloy after friction stir process exhibits enhanced cell adhesion and proliferation.•The composite layer shows an increase of corrosion potential.
Although Ti-6Al-4V has been widely used in biomaterial field. Compared with other classes of materials, it still encounters some problems such as low surface hardness and relative low biocompatibility. To solve these problems friction stir processing (FSP) was applied to fabricate a nanosized composite layer of TiO2 and Ti-6Al-4V. Uniform distribution of TiO2 particles with some clusters on the surface of alloy can be observed. Due to severe plastic deformation and stirring heat, nanocrystallines and amorphous TiO2 can be observed in stir zone. FSPed samples show significant improvement in surface microhardness and biocompatibility due to its modified structure compared with original sample. In addition, through corrosion behaviors of the samples in simulated body fluid, it is found that FSP can enhance whilst TiO2 reduces the possibility and corrosion rate of material in environment of human body.
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•Graphene reacted with Ti matrix to form TiC nanotwin during friction stir process.•Stir zone near surface contained more TiC and obtained higher hardness.•Fewer slip systems in stir ...zone were confirmed by in situ microcompression tests.
Gradient materials have significant potential to break strong plastic tradeoffs. Graphene with a strong affinity for titanium alloys has an influential application value for material modification. In this study, microstructure evolution and deformation behavior of graphene-based TiC/Ti6Al4V composites processed by friction stir processing (FSP) have been investigated. Electron backscattered diffraction (EBSD) reveals uniform microstructure in the stir zone (SZ). Transmission electron microscopy (TEM) observations reveal distinct microstructures at different depths from the processed surface. The SZ includes nano/micro grains and TiC nanoplates. Twin structure exists in both α matrix and TiC. Stress-induced martensitic transformation is suppressed. As depth increases, TiC gradually disappears and the FSP-induced texture {-2116} < 2–1–11 > becomes slightly stronger. Moreover, there exists special crystallographic orientation relation: (111)TiC//(0001)Ti. In the base metal (BM), larger grains are observed, and dislocation structure becomes the dominant defect feature. Nanoindentation results show that hardness decreases first and then increases from the processed surface to the bulk metal. The distribution of hardness is the result of combined action of strengthening effect of TiC twins and deformation adaptation effect of α twins.
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•Grain refinement and TiZn2 intermetallic complex were found in the stir zone.•Dislocation and α″ martensite enhanced the microhardness of the composite surface.•The composite surface ...promoted cell adhesion, proliferation and osteogenic differentiation.•The composite surface inhibited bacterial adhesion and growth.
Osteogenic differentiation and antibacterial property are two-core requirements for bone implants, but typically they are not compatible. Zinc (Zn) as a common bioactive material is widely used in the medical field. A balance between antibacterial and osteogenic activity can be achieved at appropriate Zn concentration. In this study, the TNTZ/Zn micro/nano-composites were prepared by doping Zn nanoparticles onto Ti-35Nb-2Ta-3Zr (TNTZ) surface through the friction stir processing (FSP) technique. The results of material characterization revealed the homogeneous distribution of Zn, the presence of α″ martensite, and the increase in microhardness in the stir zone. Due to the solid metallurgical bonding between Zn NPs and substrate, Zn ions were released slowly and may be biologically responsive through body fluid corrosion. In terms of biological activity, the expression of adhesion-related protein vinculin and osteogenic differentiation genes were up-regulated by TNTZ/Zn, which improved the early adhesion and osteogenic differentiation of bone marrow stromal stem cells. Besides, TNTZ/Zn presented excellent antibacterial properties, and direct contact with the fine grain surface containing Zn NPs may be the dominant mechanism. TNTZ/Zn micro/nano-composites have excellent mechanical properties, osteogenic differentiation and antibacterial properties, providing an efficient strategy for titanium alloy surface modification and showing tremendous potential in dental applications.
We investigated the tensile and superelastic behaviors of Ti-35Nb-2Ta-3Zr processed by double-faced friction stir processing that results in a roughly 2 times higher yield strength with an elongation ...of 37%. The friction stir processed specimens exhibited different superelasticity as loading cycle increased. To assess the strength and deformation of gradient structure, in situ micro compression tests were conducted on stir zone and heat affected zone, revealing higher strength in stir zone and better ductility in heat affected zone. The combination of stir zone and heat affected zone could increase the strength and maintain the ductility of the specimen simultaneously.
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•Ti35Nb2Ta3Zr processed by double-faced friction stir processing obtained roughly 2 times higher yield strength.•Superelasticity showed different tendency after friction stir process.•Higher strength in stir zone and better ductility in heat affected zone were confirmed by in situ microcompression tests.
Gradient materials can achieve both external strengthening and internal toughening, which has great potential to break the strong plastic tradeoff. Titanium carbide (TiC) particle is conducive to ...form a wearable surface in biomedical Titanium (Ti) alloy. In this work, gradient TiC/Ti6Al4V composites were successfully prepared by friction stir processing (FSP). Microstructure, texture and mechanical properties of the material were systematically characterized. Scanning electron microscopy (SEM) showed that the equiaxed grains near the machined surface were transformed into elongated grains inside. The results of energy spectrum analysis (EDS) showed that there was element aggregation near TiC particles. X-ray diffraction (XRD) indicated martensitic transformation in the stir zone and in the transition zone. The results of nano indentation showed that the hardness of stir zone was higher. In order to promote recrystallization and improve the hardness of the transition zone, high temperature rapid heat treatment was carried out after FSP. When the sample was heated at 700 °C and cooled in the furnace, the hardness increased to the maximum. In the process of rapid heating, the dissolution of elements near TiC particles also led to the increase of hardness. This study provides a new idea for surface modification of gradient titanium alloy by using FSP method to improve its mechanical properties.
It is known that the microbiome affects human physiology, emotion, disease, growth, and development. Most humans exhibit reduced appetites under high temperature and high humidity (HTHH) conditions, ...and HTHH environments favor fungal growth. Therefore, we hypothesized that the colonic mycobiota may affect the host's appetite under HTHH conditions. Changes in humidity are also associated with autoimmune diseases. In the current study mice were fed in an HTHH environment (32°C ± 2°C, relative humidity 95%) maintained
an artificial climate box for 8 hours per day for 21 days. Food intake, the colonic fungal microbiome, the feces metabolome, and appetite regulators were monitored. Components of the interleukin 17 pathway were also examined. In the experimental groups food intake and body weight were reduced, and the colonic mycobiota and fecal metabolome were substantially altered compared to control groups maintained at 25°C ± 2°C and relative humidity 65%. The appetite-related proteins LEPT and POMC were upregulated in the hypothalamus (
< 0.05), and
gene expression was downregulated (
< 0.05). The expression levels of PYY and O-linked β-N-acetylglucosamine were altered in colonic tissues (
< 0.05), and interleukin 17 expression was upregulated in the colon. There was a strong correlation between colonic fungus and sugar metabolism.
some metabolites of cholesterol, tromethamine, and cadaverine were significantly increased. There was significant elevation of the characteristic fungi
, and associated appetite suppression and interleukin 17 receptor signaling activation in some susceptible hosts, and disturbance of gut bacteria and fungi. The results indicate that the gut mycobiota plays an important role in the hypothalamus endocrine system with respect to appetite regulation
the gut-brain axis, and also plays an indispensable role in the stability of the gut microbiome and immunity. The mechanisms involved in these associations require extensive further studies.
The incorporation of nanoparticles into metallic biomaterials has been recognized as a significant approach to improve their bioactivity for biomedical applications. In this study, friction stir ...processing (FSP) was employed to incorporate TiO2 nanoparticles as bioactive reinforcement into the β titanium alloy Ti–35Nb–2Ta–3Zr (TNTZ) matrix to construct an integrated micro-nano composite layer. The effect of different TiO2 contents on the osteogenic capacity of rat bone marrow stromal stem cells (BMSCs) was studied. The TiO2/TNTZ composite layer exhibited a refined grain structure with a mean grain size of approximately 10 μm and a characteristic surface morphology of pronounced peaks and valleys with enhanced RSkw and RKur values. Moreover, TiO2/TNTZ significantly promoted the adhesion, proliferation, and spreading of BMSCs, upregulated the expression of genes related to osteogenesis (ALP and Runx2) up to nearly 1.5 times, and enhanced the expression of ALP and OCN (P < 0.05). The novel FSPed TiO2/TNTZ micro-nano composite possesses excellent surface characteristics and favorable biological activities, manifesting vast potential for upcoming clinical applications.
A pure Al2O3 sol was used as a substitute for water as a medium for preparing a ceramic slurry. With an Al2O3 sol addition, it became easy to control the microstructure and pore morphologies of the ...porous Al2O3 ceramics by adjusting the solids loading, composition of the ceramic slurries, and the cooling methods. SEM showed that the sol-containing ceramic slurry combined with the freeze casting processing can easily prepare porous Al2O3 ceramics with different pore sizes and morphologies. The porous Al2O3 ceramics prepared from 70 to 90 wt% solids loading sol-containing Al2O3 slurries and sintered at 1500 C for 2 h had open porosities from 81.7% to 64.6%.
NiTi alloy has a wide range of applications as a biomaterial due to its high ductility, low corrosion rate, and favorable biocompatibility. Although Young's modulus of NiTi is relatively low, it ...still needs to be reduced; one of the promising ways is by introducing porous structure. Traditional manufacturing processes, such as casting, can hardly produce complex porous structures. Additive manufacturing (AM) is one of the most advanced manufacturing technologies that can solve impurity issues, and selective laser melting (SLM) is one of the well-known methods. This paper reviews the developments of AM-NiTi with a particular focus on SLM-NiTi utilization in biomedical applications. Correspondingly, this paper aims to describe the three key factors, including powder preparation, processing parameters, and gas atmosphere during the overall process of porous NiTi. The porous structure design is of vital importance, so the unit cell and pore parameters are discussed. The mechanical properties of SLM-NiTi, such as hardness, compressive strength, tensile strength, fatigue behavior, and damping properties and their relationship with design parameters are summarized. In the end, it points out the current challenges. Considering the increasing application of NiTi implants, this review paper may open new frontiers for advanced and modern designs.
Additive manufacturing (AM) is among the most attractive methods to produce implants, the processes are very swift and it can be precisely controlled to meet patient's requirement since they can be ...produced in exact shape, dimension, and even texture of different living tissues. Until now, lots of methods have emerged and used in this field with diverse characteristics. This review aims to comprehensively discuss 3D printing (3DP) technologies to manufacture metallic implants, especially on techniques and procedures. Various technologies based on their main properties are categorized, the effecting parameters are introduced, and the history of AM technology is briefly analyzed. Subsequently, the utilization of these AM-manufactured components in medicine along with their effectual variables is discussed, and special attention is paid on to the production of porous scaffolds, taking pore size, density, etc., into consideration. Finally, 3DP of the popular metallic systems in medical applications such as titanium, Ti6Al4V, cobalt-chromium alloys, and shape memory alloys are studied. In general, AM manufactured implants need to comply with important requirements such as biocompatibility, suitable mechanical properties (strength and elastic modulus), surface conditions, custom-built designs, fast production, etc. This review aims to introduce the AM technologies in implant applications and find new ways to design more sophisticated methods and compatible implants that mimic the desired tissue functions.
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