Welcome to the IKCEST
Materials Letters

Materials Letters

Archives Papers: 2,790
Please choose volume & issue:
Phase composition and ionic conductivity of zirconia stabilized with scandia and europia
J.P. Souza; R.L. Grosso; R. Muccillo; E.N.S. Muccillo;
Abstracts:Sintered specimens of zirconia-10 mol% scandia pure and codoped (up to 1.25 mol%) with europium sexquioxide were prepared by solid-state synthesis, aiming to stabilize at room temperature the high-conductivity cubic phase. High-temperature X-ray diffraction and differential scanning calorimetry results reveal that small amounts of the codopant reduce the enthalpy of phase transition, and full stabilization is evidenced for 1 mol% europium sexquioxide. The low-temperature (<600 °C) ionic conductivity increases with increasing codopant content.
High temperature wettability between CMAS and YSZ coating with tailored surface microstructures
Y.X. Kang; Y. Bai; G.Q. Du; F.L. Yu; C.G. Bao; Y.T. Wang; F. Ding;
Abstracts:In the present work, the wetting behavior of molten calcium-magnesium-aluminum-silicate (CMAS) on femtosecond laser ablated YSZ coatings is comparatively studied. The results suggest that femtosecond laser ablated coating possesses smaller initial contact angle compared with as-sprayed or polished YSZ coatings, but lower spreading rate and larger equilibrium contact angle. This difference can be attributed to: 1) restricted CMAS spreading by the ablated squares through pinning the solid-liquid-vapor triple-phase contact line; 2) retarded CMAS penetration by microrod-shaped structure inside the ablated squares. This study provides an effective method to improve the CMAS resistance of YSZ coating by femtosecond laser.
Fe-Zr-N films: Effect of nitrogen content and nitrogen-to-zirconium concentration ratio on saturation induction
E.N. Sheftel; E.V. Harin;
Abstracts:Films FexZr9Ny (x = 86 ÷ 77, y = 5 ÷ 14, at.%) prepared by rf reactive magnetron sputtering were used to study the effect of nitrogen content and nitrogen-to-zirconium concentration ratio on their phase composition and saturation induction Bs . It was shown that the films containing 9 at.% Zr and characterized by the nitrogen-to-zirconium ratio ≥1 have the two-phase structure, which forms during deposition and comprises α-Fe(N) solid solution and ZrN nitride. The Bs dependence on the nitrogen content in α-Fe(N) solid solution was found to be linear.
Phosphorus adsorption characteristics of alum sludge: Adsorption capacity and the forms of phosphorus retained in alum sludge
Qingjie Hou; Panpan Meng; Haiyan Pei; Wenrong Hu; Yang Chen;
Abstracts:Adsorption is an effective method for phosphorus removal from eutrophic waters. Phosphorus adsorption is affected by various factors, such as the nature of the adsorbent, the characteristics of the raw water, etc. This study investigated the effect of alum sludge chemical components on adsorption capacity and the forms of P retained in alum sludge. Results showed that alum sludge can be used as a good candidate material for P adsorption, and components of Al, Ca and initial concentration of P had a significant effect on P adsorption. All the sampled sludges had high P adsorption capacity ranging from 2.06 to 6.06 mg P g−1 sludge. Derived from four different water treatment plants in Shandong province, Yu Qing alum sludge had the largest P adsorption capacity (6.06 mg P g−1), followed by Xue Shan and Que Hua, while San He sludge had the least. Sequential P extraction test indicated that most of the P forms stored in the sludges are in the inorganic forms, and the relative proportion illustrated that most of the P fractions bound to Ca (AP) and P-Al, Fe (NAIP) in all samples. Utilization of alum sludge as P adsorbent has become a win–win technology for water treatment and waste management.
Facile hydrothermal synthesis and electrochemical properties of (NH4)2V4O9 sheets for supercapacitor electrode with excellent performance
Xiaoyu Liu; Yifu Zhang; Jiqi Zheng; Changgong Meng;
Abstracts:A facile and versatile method for synthesis of novel ammonium vanadium oxide [(NH4)2V4O9] sheets is developed by a simple hydrothermal route. It is found that the synthetic conditions play an important role in the successful synthesis of (NH4)2V4O9 sheets, and the favorable condition is NH4VO3/H2C2O4·2H2O = 1/1 at 180 °C for 48 h. (NH4)2V4O9 sheets exhibit the square-like shape with several nanometers in thickness, BET specific surface area of 16 m2 g−1 and pore volume of 0.16 cm3 g−1. Electrochemical properties of (NH4)2V4O9 sheets are firstly investigated as supercapacitor electrodes by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). (NH4)2V4O9 sheets exhibit electrical storage based on the faradaic mechanism with excellent capacity and rate capability. Specific capacitance of (NH4)2V4O9 sheets reaches to 249F g−1 at a current density of 0.5 A g−1, suggesting that (NH4)2V4O9 sheets can be promising potential as electrode material applied to supercapacitors.
Manufacture of sustainable clay ceramic composite with composition SiO2-Al2O3-CaO-K2O materials valuing biomass ash from olive pomace
E. Bonet-Martínez; L. Pérez-Villarejo; D. Eliche-Quesada; P.J. Sánchez-Soto; B. Carrasco-Hurtado; E. Castro-Galiano;
Abstracts:Fly ash is a biomass combustion by-product produced by dragging ash from the base of the furnace. Disposing of ash is a growing economic and environmental burden. Based on physical and chemical properties, fly ash could be used in the manufacture of construction materials. This paper investigates the influence of biomass fly ash from olive pomace as additive to manufacture of clay ceramic composite materials. Fired clay brick at 950 °C were prepared containing between 0 and 25 wt% fly ash. Final products are studied by water absorption, bulk density, loss of ignition, linear shrinkage, compressive strength and physisorption N2. The results reveal that the porosity of the materials increases with the level of fly ash replacement (10% up to 25 wt%) resulting in to increased water absorption and decreased compressive strength. Fired clay brick developed in this study can be used for construction materials based on criteria of the current regulations.
Magnetron sputtered NbN thin film electrodes for supercapacitors
Hao Shen; Binbin Wei; Dongfang Zhang; Zhengbing Qi; Zhoucheng Wang;
Abstracts:Selecting suitable electrode materials is the key to develop high-performance supercapacitors. Herein, we report the niobium nitride (NbN) thin films prepared by reactive magnetron sputtering and investigate their electrochemical performances when used as supercapacitor electrodes. NbN thin film electrodes can achieve the optimal electrochemical performance with a volumetric capacitance of 707.1 F cm−3 and an outstanding cycling stability (remaining 92.2% after 20,000 cycles). Such impressive properties render the NbN thin films qualified as the promising candidates for supercapacitors or other energy storage systems.
Segregated conductive CNTs/HDPE/UHMWPE composites fabricated by plunger type injection molding
Wei Zhai; Ruizhou Sun; Hongling Sun; Miaoning Ren; Kun Dai; Guoqiang Zheng; Chuntai Liu; Changyu Shen;
Abstracts:The advantages of segregated conductive polymer composites are greatly hampered owing to its limited preparation technology, which seriously relies on hot compression with low efficiency. The plunger type injection molding (PTIM) is employed to fabricate segregated carbon nanotubes (CNTs)/high density polyethylene (HDPE)/ultra-high molecular weight polyethylene (UHMWPE) composites in this paper, which lowers the production cycle by 45%, compared with the conventional hot compression. The morphology and conductive properties are investigated in detail. Graceful segregated conductive network and a very low percolation threshold (0.45 vol%) of the polymer composites have both been achieved. The present processing technique with short production cycle provides a fancy idea to realize segregated conductive polymer composite in mass production.
Biomass fly ash and aluminium industry slags-based geopolymers
L. Pérez-Villarejo; E. Bonet-Martínez; D. Eliche-Quesada; P.J. Sánchez-Soto; J.Mª. Rincón-López; E. Castro-Galiano;
Abstracts:Geopolymers are a new class of non-Portland cements produced using an alumino-silicate material and an activating solution, which is mainly composed of sodium or potassium and waterglass to be subsequently cured at relatively low temperatures. Those can be formulated by adding natural minerals, waste and/or industrial by-products. The study investigates the microstructural properties of geopolymers synthesized from metakaolin (MK) and the admixture of fly ash (FBA) and aluminium industry slags (AIS) at different ages of curing. Five different geopolymer compositions were prepared and characterized by XRD, ATR-FTIR and SEM/EDS. The study revealed that geopolymeric gels are identified, which show mainly glassy microstructures, in agreement with the X-ray amorphous diffraction patterns, broad FTIR features and confirmed by SEM/EDS, with promising results prior to an industrial scale.
Aligned keratin submicrometric-fibers for fibroblasts guidance onto nanogrooved titanium surfaces for transmucosal implants
Sara Ferraris; Vincenzo Guarino; Andrea Cochis; Alessio Varesano; Iriczalli Cruz Maya; Claudia Vineis; Lia Rimondini; Silvia Spriano;
Abstracts:Biomaterials surface modification represents a very attractive tool to modulate host tissue response. Surface modifications of titanium for bone contact applications have been widely investigated, while only few papers can be found regarding modifications aimed at soft tissue contact. However, soft tissue healing represents a crucial step for percutaneous/transmucosal titanium implants success. Fibroblasts, the soft tissues most representative cells, are known to be sensitive to surface topography. Anyhow, fibroblasts adhesion and spread can be more influenced by the presence of attractive macromolecules; so, within a grooved and keratin-coated Ti surface, cells will align following the strongest biochemical guide provided by keratin submicrometric-fibers. In order to obtain the most effective cell stimulation/guidance keratin submicrometric-fibers should be aligned to substrate nanogrooves. Despite the very promising cells guidance provided by keratin submicrometric-fibers, the strong limitation to their synthesis is related to the macromolecules high sensitivity to environmental parameters (temperature/humidity/pH) which can seriously compromise the feasibility and reproducibility of the final submicrometric-fibers layer. Accordingly, this work has the aim to obtain, for the first time, a coating of submicrometric keratin fibers aligned to the nanogrooves of a Ti substrate, in order to validate the attitude of the coated surface to impart additive topographical plus biochemical signals in the same direction for the stimulation of fibroblasts repopulation.
Hot Journals