scholarly journals Structural and Electrochemical Properties of Dense Yttria-Doped Barium Zirconate Prepared by Solid-State Reactive Sintering

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3083 ◽  
Author(s):  
Dae Yun ◽  
Jaegyeom Kim ◽  
Seung-Joo Kim ◽  
Jong-Heun Lee ◽  
Jong-Nam Kim ◽  
...  
Keyword(s):  
Solid State ◽  
Electrochemical Properties ◽  
Electrochemical Impedance ◽  
Sintering Temperature ◽  
Proton Conductors ◽  
Barium Zirconate ◽  
Reactive Sintering ◽  
Practical Utilization ◽  
Average Grain Size ◽  
Ceramic Fuel Cells

For practical utilization of proton-conducting ceramic fuel cells and electrolyzers, it is essential to lower the sintering temperature and processing time of BaZrO3-based proton conductors. We investigated the effect of sintering temperature and time on the structural and electrochemical properties of dense BaZr0.8Y0.2O3−δ (BZY) prepared by a solid-state reactive sintering process, using NiO as a sintering aid. The sintered BZY prepared from the micronized precursor powder exhibited a density higher than 93%, and an average grain size in the range of 0.6 to 1.4 μm. The orthorhombic BaY2NiO5 phase was also observed in the sintered BZY from the combined conventional and synchrotron X-ray diffraction measurements. Electrochemical impedance spectroscopy showed that the total proton conductivities of BZY can be modulated by sintering temperature in a wet reducing atmosphere. The maximum total ion transport number achieved was 0.89 at 600 °C, and the maximum power density of the symmetric BZY electrolyte supported cell with Pt electrodes was 5.24 mW·cm−2 at 900 °C.

Solid-state reactive sintering mechanism for large-grained yttrium-doped barium zirconate proton conducting ceramics

2010 ◽  
Vol 20 (30) ◽  
pp. 6333 ◽  
Author(s):  
Jianhua Tong ◽  
Daniel Clark ◽  
Lisa Bernau ◽  
Michael Sanders ◽  
Ryan O'Hayre
Keyword(s):  
Solid State ◽  
Barium Zirconate ◽  
Reactive Sintering ◽  
Proton Conducting ◽  
Sintering Mechanism

scholarly journals Comparative Study of Reactive and Non-reactive Spark Plasma Sintering Routes for The Production of TaB2-TaC Composites

2021 ◽  
Author(s):  
Melis Kaplan Akarsu ◽  
Ipek Akin ◽  
Filiz Sahin ◽  
Gultekin Goller
Keyword(s):  
Spark Plasma Sintering ◽  
Oxidation Behavior ◽  
Sintering Temperature ◽  
Single Step ◽  
Reactive Sintering ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Significant Difference ◽  
Spark Plasma

Abstract The influence of two different spark plasma sintering-based processing routes (i.e., reactive SPS (RSPS) and non-reactive SPS) on the properties of TaB2-TaC composites was investigated. Ta2O5 and B4C powders were used as starting materials in the RSPS method, and synthesis and densification of TaB2-TaC composites were accomplished in a facile single step. The effect of sintering temperature and time on the microstructure and densification of the in-situ RSPS were investigated. The obtained results were compared with non-reactive spark plasma sintered TaB2-TaC composites. The highest densification (~ 99.5 %) was achieved for the TaB2-TaC composite with 6.64 vol% TaC after reactive sintering at 1550 °C under 40 MPa with a 5 min holding time. Although lower SPS temperature was used in the RSPS method, better densification and higher Vickers hardness were obtained compared to the non-reactive SPS. While platelet-shaped TaC formation was observed in both processes, the average grain size was smaller in the sample produced by the RSPS method. On the other hand, no significant difference was detected in fracture toughness and oxidation behavior of the composites produced by RSPS and non-reactive SPS.

scholarly journals Effect of starting materials and sintering temperature on microstructure and optical properties of Y2O3:Yb3+ 5 at% transparent ceramics

2020 ◽  
Author(s):  
R. P. Yavetskiy ◽  
A. E. Balabanov ◽  
S. V. Parkhomenko ◽  
O. S. Kryzhanovska ◽  
A. G. Doroshenko ◽  
...  
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Sintering Temperature ◽  
Raw Materials ◽  
High Energy ◽  
Reactive Sintering ◽  
Average Grain Size ◽  
Median Particle ◽  
Energy Ball ◽  
Sintering Method

Abstract Y2O3:Yb3+ 5 at% ceramics have been synthesized by the reactive sintering method using different commercial yttria powders (Alfa-Micro, Alfa-Nano, and ITO-V) as raw materials. It has been shown that all Y2O3 starting powders consist from agglomerates up to 5–7 µm in size which are formed from 25–60 nm primary particles. High-energy ball milling allows to significantly decreasing the median particle size D50 below 500 nm regardless of the commercial powders used. Sintering experiments indicate that powder mixtures fabricated from Alfa-Nano yttria powders have the highest sintering activity, while (Y0.86La0.09Yb0.05)2O3 ceramics sintered at 1750 °C for 10 h are characterized by the highest transmittance of about 45%. Y2O3:Yb3+ ceramics have been obtained by the reactive sintering at 1750–1825°C using Alfa-Nano Y2O3 powders and La2O3+ZrO2 as a complex sintering aid. The effects of the sintering temperature on densification processes, microstructure, and optical properties of Y2O3:Yb3+ 5 at% ceramics have been studied. It has been shown that Zr4+ ions decrease the grain growth of Y2O3:Yb3+ ceramics for sintering temperatures 1750–1775 °C. Further increasing the sintering temperature was accompanied by a sharp increase of the average grain size of ceramics referred to changes of structure and chemical composition of grain boundaries, as well as their mobility. It has been determined that the optimal sintering temperature to produce high-dense yttria ceramics with transmittance of 79%–83% and average grain size of 8 µm is 1800 °C. Finally, laser emission at ∼1030.7 nm with a slope efficiency of 10% was obtained with the most transparent Y2O3:Yb3+ 5 at% ceramics sintered.

The study of the electrochemical properties of zinc-rich coating on the base of water sodium silicate

2019 ◽  
Vol 24 (4) ◽  
pp. 51-58
Author(s):  
Le Hong Quan ◽  
Nguyen Van Chi ◽  
Mai Van Minh ◽  
Nong Quoc Quang ◽  
Dong Van Kien
Keyword(s):  
Carbon Steel ◽  
Electrochemical Properties ◽  
Sodium Silicate ◽  
Cathodic Protection ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Electrical Contact ◽  
Electrochemical Impedance Spectra ◽  
Pure Zinc ◽  
Electric Circuits

The study examines the electrochemical properties of a coating based on water sodium silicate and pure zinc dust (ZSC, working title - TTL-VN) using the Electrochemical Impedance Spectra (EIS) with AutoLAB PGSTAT204N. The system consists of three electrodes: Ag/AgCl (SCE) reference electrode in 3 M solution of KCl, auxiliary electrode Pt (8x8 mm) and working electrodes (carbon steel with surface treatment up to Sa 2.5) for determination of corrosion potential (Ecorr) and calculation of equivalent electric circuits used for explanation of impedance measurement results. It was shown that electrochemical method is effective for study of corrosion characteristics of ZSC on steel. We proposed an interpretation of the deterioration over time of the ability of zinc particles in paint to provide cathodic protection for carbon steel. The results show that the value of Ecorr is between -0,9 and -1,1 V / SCE for ten days of diving. This means that there is an electrical contact between the zinc particles, which provides good cathodic protection for the steel substrate and most of the zinc particles were involved in the osmosis process. The good characteristics of the TTL-VN coating during immersion in a 3,5% NaCl solution can also be explained by the preservation of corrosive zinc products in the coating, which allows the creation of random barrier properties.

scholarly journals Synthesis and Na+ Ion Conductivity of Stoichiometric Na3Zr2Si2PO12 by Liquid-Phase Sintering with NaPO3 Glass

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3790
Author(s):  
Yongzheng Ji ◽  
Tsuyoshi Honma ◽  
Takayuki Komatsu
Keyword(s):  
Solid State ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Ion Conductivity ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Sintering Time ◽  
Lower Activation

Sodium super ionic conductor (NASICON)-type Na3Zr2Si2PO12 (NZSP) with the advantages of the high ionic conductivity, stability and safety is one of the most famous solid-state electrolytes. NZSP, however, requires the high sintering temperature about 1200 °C and long sintering time in the conventional solid-state reaction (SSR) method. In this study, the liquid-phase sintering (LPS) method was applied to synthesize NZSP with the use of NaPO3 glass with a low glass transition temperature of 292 °C. The formation of NZSP was confirmed by X-ray diffraction analyses in the samples obtained by the LPS method for the mixture of Na2ZrSi2O7, ZrO2, and NaPO3 glass. The sample sintered at 1000 °C for 10 h exhibited a higher Na+ ion conductivity of 1.81 mS/cm at 100 °C and a lower activation energy of 0.18 eV compared with the samples prepared by the SSR method. It is proposed that a new LPE method is effective for the synthesis of NZSP and the NaPO3 glass has a great contribution to the Na+ diffusion at the grain boundaries.

scholarly journals Pitting Corrosion of Type 316L Stainless Steel Elaborated by the Selective Laser Melting Method: Influence of Microstructure

2021 ◽  
Author(s):  
V. Vignal ◽  
C. Voltz ◽  
S. Thiébaut ◽  
M. Demésy ◽  
O. Heintz ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
316L Stainless Steel ◽  
Electrochemical Impedance ◽  
Chemical Properties ◽  
Passive Films ◽  
First Order ◽  
Average Grain Size ◽  
Type 316L ◽  
Pure Matrix ◽  
Type 316L Stainless Steel

AbstractThe microstructure of two sets of 316L alloys (SLM and wrought structure) is determined using SPECTROMAXx stationary metal analyzer, FE-SEM/EDS and XRD. The physical–chemical properties of the passive films are also investigated by means of XPS, Auger after sputtering and electrochemical impedance spectroscopy measurements. Differences and similarities between the two sets of alloys are then identified. The corrosion behavior of alloys is investigated in NaCl solution at the macro- and microscale (microcapillary technique). It was found that the inclusion/particles cleanliness is the first-order parameter explaining differences between 316L(WS) and 316L(SLM). In the absence of particles (pure matrix), the two sets of alloys have the same corrosion behavior. Residual stresses, the average grain size, the PREN and the passive films properties are of second order.

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