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One-dimensional (1D) structures, such as carbon nanotubes and carbon fibers, used as reinforcements in advanced carbon materials, have been greatly appreciated but facing with some significant challenges of dispersion and interfacial bonding. We utilized electrospinning technology to create a new 1D nanofiller. This material is a superfine fiber composed of polyacrylonitrile (PAN) with a high nanodiamond (ND) content of 75 %, which is referred to as PDNF. During the preparation process, these nanofillers were blended with natural flake graphite (NFG) through electro-spraying. The as-prepared mixture served as the precursor powder sintered into NFG-based high-strength bulk graphite (HPG). During spark plasma sintering at 1800 °C, fibrous PDNF undergoes a phase transformation of diamond to graphite, with onion carbon pinning into and markedly reducing cleavage along the (002) plane of NFG, foundational to the high strength of NFG-based HPG. The PDNF's fiber-like structure and NFG's flake structure greatly increase the interfacial area between the matrix and reinforcement. Furthermore, the PDNF excels at blunting and deflecting cracks, thus bolstering the NFG-based HPG's overall resistance to crack propagation. The density, Young's modulus, and flexural strength of the as-prepared NFG-based HPG achieve 1.65 g/cm3, 17.4 GPa, and 145 MPa, respectively. Most importantly, this process can be a general approach for other high-performance composite materials. [ABSTRACT FROM AUTHOR]

Degradation due to molten salt attack is one of the failure mechanisms of thermal barrier coatings. Thermochemical attack of the salt mixture Na 2 SO 4 –30 mol% NaVO 3 on ZrO 2 –8 mol% YO 1.5 (8YSZ) at 1100 °C for different times was investigated. In the present study, 8YSZ powder was synthesized using co-precipitation route. The graded morphologies and phase compositions were examined using SEM, XRD and Raman before and after hot corrosion test. The results obtained from XRD have shown that m-ZrO 2 and YVO 4 were the main corrosion products after hot corrosion test at 1100 °C. The results obtained from SEM and EDS observations have shown that large polyhedron crystals of m-ZrO 2 and rod-like crystals of YVO 4 formed as hot corrosion products after hot corrosion test for 6 h and 24 h. The phase transformation and chemical interaction are the primary corrosion mechanisms for degradation of 8YSZ ceramic. [ABSTRACT FROM AUTHOR]

ZrO 2 :Eu 3+ nanocrystals were synthesized by hydrothermal technique. Effects of Eu 3+ -doping and annealing on the morphology, crystal structure and fluorescence properties of the resultant ZrO 2 :Eu 3+ nanocrystals were investigated. The morphology and crystal structure of the ZrO 2 :Eu 3+ nanocrystals were characterized by TEM, XRD, FT-IR and Raman, respectively. The fluorescence properties were explored by PL and decay curve. The results showed that both the Eu 3+ doping concentration and annealing temperature had influence on the crystal structure and fluorescence properties of ZrO 2 :Eu 3+ nanocrystals. For the low Eu 3+ -doping concentration, the amount of the tetragonal phase decreased with increasing the annealing temperature. The Eu 3+ ion is trivalent rare earth (RE 3+ ) activator, which can stabilize the tetragonal as well as the cubic structure of ZrO 2 . The ZrO 2 :Eu 3+ nanocrystals with tetragonal or cubic structure may find potential applications as the raw material for producing the transparent ceramics with efficient fluorescence properties. [ABSTRACT FROM AUTHOR]

As a toughening agent, LaPO 4 has been used to improve several properties of ceramics. In such applications, its compatibility with the matrix material should be considered first. In this study, the compatibility of LaPO 4 and magnesium lanthanum hexa-aluminate (LaMgAl 11 O 19 , LMA) was elucidated at temperatures ranging from room temperature to 1600 °C. The compositions, thermal stabilities, thermal conductivities and microstructures of the above-mentioned materials were analysed using X-ray diffraction, thermogravimetry-differential scanning calorimetry, thermal conductivity tester and scanning electron microscopy. The results indicated that the two materials maintained a good compatibility at temperatures lower than 1600 °C. At 1600 °C, the diffusion of La was observed to alter the chemical composition of LaPO 4 and accelerate its reaction with LMA, leading to the formation of LaAlO 3 and magnesium lanthanum aluminium oxide, resulting in the increase of thermal conductivity. [ABSTRACT FROM AUTHOR]

As a rare earth hexaaluminate, LaMgAl 11 O 19 (LMA) has been one of the most promising materials used as thermal barrier coatings (TBCs). A large amount of amorphous phase, however, often exists in the plasma-sprayed LMA coating and significantly reduces the service lifetime of TBCs. In this study, La 1- x Gd x MgAl 11 O 19 (x = 0, 0.2, 0.4, 0.6, and 0.8) ceramic powders are synthesised by solid-state reaction, and all of these powders are employed to prepare the corresponding coatings. The phase compositions and microstructures of samples are examined by X-ray diffraction and scanning electron microscopy, respectively. The linear thermal expansion behaviour and thermal cycling behaviour of the coatings are also analysed. The results show that the amorphous phase content is decreased and the thermal expansion behaviour is improved by doping the coatings with Gd 2 O 3. The thermal cycling lifetime of the coating, however, basically remains unchanged. [ABSTRACT FROM AUTHOR]

This study investigates the hot corrosion behaviours of La 1- x Gd x MgAl 11 O 19 (x = 0, 0.2, 0.4, 0.6, 0.8) bulk ceramics and ceramic coatings. The hot corrosion resistance of the ceramic coating was inferior to that of the bulk ceramic, owing to the formation of an amorphous phase during the plasma spraying process. The smaller size of Gd3+ in comparison with La3+ facilitated the ready combination of Gd3+ with V O 4 3 − . LaVO 4 was obtained as the corrosion product in the LaMgAl 11 O 19 (LMA) sample. Upon doping the LMA with Gd 2 O 3 , the LaVO 4 was almost entirely replaced by GdVO 4. Therefore, the sacrificial action of GdMgAl 11 O 19 protected the LMA from hot corrosion, while also providing a new method for modifying the corrosion resistance of molten slag. [ABSTRACT FROM AUTHOR]

The rationale of this study was based on the hypothesis that mechanical strength and ion release in dental composite resins containing 50 wt% calcium phosphate fillers, including spherical micrometer-scale modified dicalcium phosphate anhydrous (Ms-DCPA) and synthetic micro- and nanometer-scale rod-like hydroxyapatite (HA) (respectively abbreviated as Mr-HA and Nr-HA), led to a superior ability to re-precipitate. The reinforced resin properties were measured before and after immersion for 24 h and further exposure to thermal fatigue between 5 and 55 °C for 600 and 2400 cycles. The groups of resins reinforced with Mr-HA and Nr-HA showed a significant increase in their microhardness and ability to re-precipitate after immersion and through thermal fatigue. The 50% Mr-HA sample had the highest anti-decline ability for flexural strength and modulus after thermal fatigue among all three types of fillers, whereas the Nr-HA sample had the lowest flexural strength and modulus. Filler morphologies that had a higher aspect ratio of length to width had better re-mineralization ability after immersion, but the Mr-HA sample showed the advantage of avoiding the agglomeration problems that occurred in the case of Nr-HA. Micro-rod HA-reinforced composite resins have superior potential applications in dental caries restoration. [ABSTRACT FROM AUTHOR]

ZrB 2 – ZrC/Ni composite powders were successfully produced from a Ni – Zr – B 4 C system by self-propagating high-temperature synthesis (SHS), and ZrB 2 – ZrC/Ni cermet coatings were deposited on a magnesium alloy substrate by atmospheric plasma spraying (APS) using the SHS-derived powders as feedstock powders. Microstructure and phase composition of the SHS powders and APS coatings were investigated by scanning electron microscopy and X-ray diffraction, respectively. Microhardness and wear resistance of the coatings were examined by using a Vickers hardness tester and pin-on-desk tribometer. The coatings exhibited lamellar and porous structure, mainly consisting of ZrB 2 , ZrC and Ni in addition to the by-product ZrO 2 . The coatings bonded well to the substrate with the bonding strength as high as 16.27 MPa. Microhardness and wear resistance of the substrate were significantly improved by the coatings. The wear resistance of the coatings for the substrate initially increased and subsequently decreased with the increase in Ni content. The coating with 30 wt% Ni in the feedstock powder displayed the highest microhardness of 525.02±96.08 HV 0.1 and the best wear resistance for the substrate. [ABSTRACT FROM AUTHOR]