Operando Spatial and Temporal Tracking of Axial Stresses and Interfaces in Solid-state Batteries.

Solid-state batteries have the potential to replace the current generation of liquid electrolyte batteries. However, the major limitation resulting from their solid-state architecture is the gradual loss of ionic conductivity due to the loss of physical contact between the individual battery components during charging/discharging. This is mainly due to mechanical stresses caused by volume changes in the cathode and anode during lithiation and delithiation. To date, limited research has been devoted to understanding the spatio-temporal distribution of stresses during battery operation. Here, operando scanning high-energy X-ray diffraction to quantify cross-sectional axial stresses with a spatial resolution of 10 µm is used. It is shown how a non-monotonous stress distribution evolves over time during the cycling of the solid-state battery. In addition, degradation of the solid-state electrolyte in the vicinity of the lithium anode is observed and tracked periodic changes in the unit cell volume in the cathode. The presented methodology of tracking the chemo-mechanically induced stresses and interface morphology in real time in correlation with other battery parameters is believed, can provide a valuable platform for the future optimization of solid-state batteries.

Dispersion and Preparation of Nano-AlN/AA6061 Composites by Pressure Infiltration Method.

Nanomaterials play an important role in metal matrix composites (MMC). In this study, 3.0 wt.%, 6.0 wt.%, and 9.0 wt.% nano-AlN-particles-reinforced AA6061 (nano-AlN/AA6061) composites were successfully prepared by pressure infiltration technique and then hot extruded (HE) at 500 °C. The microstructural characterization of the composites after HE show that the grain structure of the Al matrix is significantly refined, varying from 2 to 20 µm down to 1 to 3 µm. Nano-AlN particles in the composites are agglomerated around the matrix, and the distribution of nano-AlN is improved after HE. The interface between AA6061 and nano-AlN is clean and smooth, without interface reaction products. The 3.0 wt.% nano-AlN/AA6061 composite shows an uppermost yield and supreme tensile strength of 333 MPa and 445 MPa, respectively. The results show that the deformation procedure of the composite is beneficial to the further dispersion of nano-AlN particles and improves the strength of nano-AlN/AA6061 composite. At the same time, the strengthening mechanism active in the composites was discussed.

The effect of surface modification of TiMg composite on the in-vitro degradation response, cell survival, adhesion, and proliferation.

This study is aimed to evaluate the influence of mechanical surface treatment on the degradation response, cell survival, adhesion, and proliferation of a TiMg composite material. Two sets of the TiMg samples with different surface characteristics were studied: i) as-machined samples (TiMg-T) and ii) samples with a mechanically modified surface (TiMg-P). Surface roughness was determined using a confocal microscope. Degradation rates (DR) were evaluated in artificial Plasma, HBSS, and NaCl 0.9%. The cell viability was evaluated using an MTT assay. The initial cell adhesion and spreading were investigated using the direct contact assay. An xCELLigence system was employed to provide real-time cell proliferation. The focal adhesion and cell morphological changes were also examined. The DR of TiMg-P decreased by ⁓5 times compared with that of TiMg-T. Surface of the TiMg-P specimens after 72 h exposure to either HBSS or Plasma was passivated by a layer enriched with bioactive Ca/P species. The cell viability of L929 and Saos-2 after 72 h incubation for TiMg-P was 94.6% and 94.8% compared with 73.8% and 74.3% obtained for TiMg-T, respectively. The direct contact assay showed that the initial adhesion and spreading of the L929 cells incubated with TiMg-P was more pronounced compared with that of TiMg-T. The proliferation rate of Saos-2 cells incubated with TiMg-P was higher when compared with that of TiMg-T, and was almost comparable to that of the DMEM-blank between the 24 and 72 h interval. TiMg-P had a pronounced difference in the number and area of Focal Adhesions (FA) compared with that of TiMg-T. The morphology of cells incubated with TiMg-P was not altered. The results confirmed that the smooth and less strained surface of the TiMg-P samples effectively improved the in-vitro degradation response, cell survival, adhesion, and proliferation.

Simple and Eco-Friendly Route from Agro-Food Waste to Water Pollutants Removal.

The current study reflects the demand to mitigate the environmental issues caused by the waste from the agriculture and food industry. The crops that do not meet the supply chain requirements and waste from their processing are overfilling landfills. The mentioned wastes contain cellulose, which is the most abundant carbon precursor. Therefore, one of the possibilities of returning such waste into the life cycle could be preparing the activated carbon through an eco-friendly and simple route. Herein, the carrot pulp from the waste was used. Techniques such as thermogravimetric analysis (TGA), elemental analysis (EA), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and x-ray diffraction (XRD) were used to investigate the thermal treatment effect during the carbon material preparation. The development of microstructure, phase formation, and chemical composition of prepared material was evaluated. The obtained carbon material was finally tested for water cleaning from a synthetic pollutant such as rhodamine B and phloxine B. An adsorption mechanism was proposed on the base of positron annihilation lifetime spectroscopy (PALS) results and attributed to the responsible interactions. It was shown that a significant carbon sorbent from the organic waste for water purification was obtained.

Bioactive Ti + Mg composites fabricated by powder metallurgy: The relation between the microstructure and mechanical properties.

Metallic implant materials are biomaterials that have experienced major development over the last fifty years, yet some demands posed to them have not been addressed. For the osseointegration process and the outcome of endosseous implantation, it is crucial to reduce the stress shielding effect and achieve sufficient biocompatibility. Powder metallurgy (PM) was utilized in this study to fabricate a new type of titanium (Ti) + magnesium (Mg) bioactive composite to enable stress-shielding reduction and obtain better biocompatibility compared with that of the traditional Ti and Ti alloys used for dental implants. Such composites are produced by well-known cost-effective and widely used PM methods, which eliminate the need for complex and costly Ti casting used in traditional implant production. The relation between the microstructure and mechanical properties of as-extruded Ti + (0-24) vol% Mg composites was investigated with respect to the Mg content. The microstructure of the composites consisted of a biodegradable Mg component in the form of filaments, elongated along the direction of extrusion, which were embedded within a permanent, bioinert Ti matrix. As the Mg content was increased, the discrete filaments became interconnected with each other and formed a continuous Mg network. Young's modulus (E) of the composites was reduced to 81 GPa, while other tensile mechanical properties were maintained at the values required for a dental implant material. The corrosion behavior of the Ti + Mg composites was studied during immersion in a Hank's balanced salt solution (HBSS) for up to 21 days. The elution of Mg pores formed at former Mg sites led to a further decrease of E to 74 GPa. The studied compositions showed that a new Ti + Mg metallic composite should be promising for load-bearing applications in endosseous dental implants in the future.

Titanium Ions Release from an Innovative Titanium-Magnesium Composite: an in Vitro Study.

BACKGROUND: The innovative titanium-magnesium composite (Ti-Mg) was produced by powder metallurgy (P/M) method and is characterized in terms of corrosion behavior. MATERIAL AND METHODS: Two groups of experimental material, 1 mass% (Ti-1Mg) and 2 mass% (Ti-2Mg) of magnesium in titanium matrix, were tested and compared to commercially pure titanium (CP Ti). Immersion test and chemical analysis of four solutions: artificial saliva; artificial saliva pH 4; artificial saliva with fluoride and Hank balanced salt solution were performed after 42 days of immersion, using inductively coupled plasma mass spectrometry (ICP-MS) to detect the amount of released titanium ions (Ti). SEM and EDS analysis were used for surface characterization. RESULTS: The difference between the results from different test solutions was assessed by ANOVA and Newman-Keuls test at p<0.05. The influence of predictor variables was found by multiple regression analysis. The results of the present study revealed a low corrosion rate of titanium from the experimental Ti-Mg group. Up to 46 and 23 times lower dissolution of Ti from Ti-1Mg and Ti-2Mg, respectively was observed compared to the control group. Among the tested solutions, artificial saliva with fluorides exhibited the highest corrosion effect on all specimens tested. SEM micrographs showed preserved dual phase surface structure and EDS analysis suggested a favorable surface bioactivity. CONCLUSION: In conclusion, Ti-Mg produced by P/M as a material with better corrosion properties when compared to CP Ti is suggested.

Effects of Wire EDM on the Microstructure of P/M Titanium Samples.

PURPOSE: Commercially pure titanium (CP Ti) has been recognized in dentistry for its biocompatibility, good mechanical properties and corrosion resistance. Conventional manufacturing processes can affect surface quality and result in poor bonding of dental ceramics to CP Ti. This is why powder metallurgy (P/M) and wire electro-discharge machining (WEDM) are being introduced in the manufacturing process. The aim of this study was to evaluate the effect of WEDM on the surface composition and microstructure of P/M CP Ti samples produced for bond strength testing according to ISO 9693. MATERIALS AND METHODS: Eight samples of P/M CP Ti, dimensions according to ISO 9693, were made using WEDM and divided in two groups (untreated and grinded). Microanalyses of chemical composition and microstructure of both groups were made using SEM, EDS and XDR. RESULTS: SEM and EDS analysis of untreated samples showed a thin layer on surfaces with fractures in it. Grinded samples showed homogenous structure with no layer and no fractures. XDR analysis showed high level of oxides on the surface of untreated samples, while after grinding only pure α-phase was found. CONCLUSION: WEDM is a suitable method of sample production for ISO 9693 if accompanied by grinding with silicon carbide papers P320-P4000.