Crystallite size of the graphitic phase in soot ink based on historic recipe: A potential dating tool for old manuscripts

In this paper, we report the crystallite size of the graphitic phase observed in a soot ink sample prepared based on an original Ottoman recipe in the 18th century for the first time. Intensity ratio of the D and G bands that were observed at 1384 and 1609 cm-1 respectively, revealed that the crystallite size is 24.33 nm. This corresponds to a carbon phase between graphitic and well graphitic stage. We strongly believe that this could be further used particularly for dating purposes by investigating carbon-black pigments which we have not encountered its consideration in the literature for mainly manuscripts. Here, we especially propose using the Tuinstra-Koenig relationship together with the consideration of D and G band profiles to derive the crystallite size of the graphitic phase observed in soot ink and other various carbon-black inks for the purpose of manuscript dating.

Preparation of ZrO2 in SiC coating via hydrothermal method and sintering process onto carbon/carbon composite

To reduce the defects in SiC coating, a SiC/ZrO2 composite is prepared and coated onto carbon/carbon composite via hydrothermal method and sintering process. The microstructure, surface morphology, chemical states, and elemental distribution of SiC/ZrO2 coating are analysed with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). In addition, we analyze the tribological behavior of the SiC and SiC/SiC/ZrO2 coatings and the related microstructure. The results show that SiC/ZrO2 coating is composed of SiC phase, ZrO2 phase, carbon phase, and SiO2 phase. EDS results show that Si, C, O, and Zr elements are present in the SiC/ZrO2 coating. Moreover, XPS results show the presence of SiC, ZrO2, and SiO2. According to the SEM image, the coating is dense except for some observable cracks. Notably, specimens with the SiC/ZrO2 coating have smaller, more stable friction coefficients and less weight loss than specimens with the SiC-only coating. The formation of ZrO2 strengthens the SiC coating, while the SiO2 formed in the coating acts as a lubricant and reduces the friction coefficient of the coating.

Diamond Coating Reduces Nuclear Fuel Rod Corrosion at Accidental Temperatures: The Role of Surface Electrochemistry and Semiconductivity

If we want to decrease the probability of accidents in nuclear reactors, we must control the surface corrosion of the fuel rods. In this work we used a diamond coating containing <60% diamond and >40% sp2 “soft” carbon phase to protect Zr alloy fuel rods (ZIRLO ®) against corrosion in steam at temperatures from 850 °C to 1000 °C. A diamond coating was grown in a pulse microwave plasma chemical vapor deposition apparatus and made a strong barrier against hydrogen uptake into ZIRLO® (ZIRLO) under all tested conditions. The coating also reduced ZIRLO corrosion in hot steam at 850 °C (for 60 min) and at 900 °C (for 30 min). However, the protective ability of the diamond coating decreased after 20 min in 1000 °C hot steam. The main goal of this work was to explain how diamond and sp2 “soft” carbon affect the ZIRLO fuel rod surface electrochemistry and semi conductivity and how these parameters influence the hot steam ZIRLO corrosion process. To achieve this goal, theoretical and experimental methods (scanning electron microscopy, Raman spectroscopy, electrochemical impedance spectroscopy, carrier gas hot extraction, oxidation kinetics, ab initio calculations) were applied. Deep understanding of ZIRLO surface processes and states enable us to reduce accidental temperature corrosion in nuclear reactors.

Polymer-Derived Biosilicate®-like Glass-Ceramics: Engineering of Formulations and Additive Manufacturing of Three-Dimensional Scaffolds

Silicone resins, filled with phosphates and other oxide fillers, yield upon firing in air at 1100 °C, a product resembling Biosilicate® glass-ceramics, one of the most promising systems for tissue engineering applications. The process requires no preliminary synthesis of parent glass, and the polymer route enables the application of direct ink writing (DIW) of silicone-based mixtures, for the manufacturing of reticulated scaffolds at room temperature. The thermal treatment is later applied for the conversion into ceramic scaffolds. The present paper further elucidates the flexibility of the approach. Changes in the reference silicone and firing atmosphere (from air to nitrogen) were studied to obtain functional composite biomaterials featuring a carbon phase embedded in a Biosilicate®-like matrix. The microstructure was further modified either through a controlled gas release at a low temperature, or by the revision of the adopted additive manufacturing technology (from DIW to digital light processing).

Efficient Improvement in Fracture Toughness of Laminated Composite by Interleaving Functionalized Nanofibers

Functionalized polyacrylonitrile (PAN) nanofibers were used in the present investigation to enhance the fracture behavior of carbon epoxy composite in order to prevent delamination if any crack propagates in the resin rich area. The main intent of this investigation was to analyze the efficiency of PAN nanofiber as a reinforcing agent for the carbon fiber-based epoxy structural composite. The composites were fabricated with stacked unidirectional carbon fibers and the PAN powder was functionalized with glycidyl methacrylate (GMA) and then used as reinforcement. The fabricated composites’ fracture behavior was analyzed through a double cantilever beam test and the energy release rate of the composites was investigated. The neat PAN and functionalized PAN-reinforced samples had an 18% and a 50% increase in fracture energy, respectively, compared to the control composite. In addition, the samples reinforced with functionalized PAN nanofibers had 27% higher interlaminar strength compared to neat PAN-reinforced composite, implying more efficient stress transformation as well as stress distribution from the matrix phase (resin-rich area) to the reinforcement phase (carbon/phase) of the composites. The enhancement of fracture toughness provides an opportunity to alleviate the prevalent issues in laminated composites for structural operations and facilitate their adoption in industries for critical applications.

Effects of the Ethyne Flow Ratio on Structures and Mechanical Properties of Reactive High Power Impulse Magnetron Sputtering Deposited Chromium-Carbon Films

Chromium-carbon films were deposited by utilizing reactive high-power impulse magnetron sputtering with different mixture ratios of ethyne and argon with a constant deposition total pressure while the deposition temperature, pulse frequency, duty cycle and average power of the chromium cathode remain the same. The microstructure and chemical bonding of the obtained films within different composition were compared. The results show that with the increasing ethyne ratio, the carbon content in films increases linearly with two slopes. Moreover, the microstructure of the deposited film changes from a dense glassy structure into a columnar structure, even a clusters structure. The sp2-C bonding in films decreases but the Cr–C bonding increases with decreasing the ethyne ratio. This reveals the main phase of films changes from a hydrogenated amorphous carbon phase into a glassy amorphous chromium carbide phase. Such changes of the microstructure and phase cause a large difference on the film hardness and elasticity.