scholarly journals (Ti,Cr)C-Based Cermets with Varied Nicr Binder Content via Elemental SHS for Perspective Cutting Tools

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 412
Author(s):  
Stepan Vorotilo ◽  
Philipp V. Kiryukhantsev-Korneev ◽  
Boris S. Seplyarskii ◽  
Roman A. Kochetkov ◽  
Nail I. Abzalov ◽  
...  
Keyword(s):  
Solid Solution ◽  
Gas Permeability ◽  
Combustion Velocity ◽  
Cutting Tools ◽  
Secondary Phase ◽  
Fold Increase ◽  
Combustion Products ◽  
Secondary Phase Formation ◽  
Secondary Reactions ◽  
Nickel Binder

The effects of granulation of reactive mixtures Ti-Cr-C and Ti-Cr-C-Ni on the combustion temperature and velocity, as well as phase composition and mechanical properties (crushing ability) of combustion products, were studied. Granulation was associated with a 1.5-fold increase in combustion velocity, caused by a nearly 10-fold increase in gas permeability. Secondary reactions between TiC, Cr7C3, and molten Ni led to the formation of (Ti,Cr)C FCC solid solution and Ni2.88Cr1.12 intermetallics. After the combustion of Ti-Cr-C-Ni mixtures, prolonged fluorescence was registered, suggesting the exothermic nature of secondary phase formation reactions. The introduction of the nickel binder decreased the content of Cr in the solid solution (Ti,Cr)C owing to the formation of the Ni2.88Cr1.12 phase. To prevent the Cr depletion from the carbide solid solution, Ni-20%Cr binder was added to the granulated 80%(Ti + C)/20%(3Cr + 2C) mixture. Combustion of granulated mixture yielded brittle porous sinter cake, which was easy to crush and mill, whereas the combustion products from the powdered mixtures were more ductile and harder to crush.

scholarly journals Influence of ZnO addition and milling process on structure and conductivity of BaCe0.2Zr0.7Y0.1O3-δ ceramics

2021 ◽  
Vol 15 (3) ◽  
pp. 288-296
Author(s):  
Ana Ana Kaori de Oliveira Ouba ◽  
Adilson Chinelatto ◽  
Edson Grzebielucka ◽  
Kethlinn Ramos ◽  
Janaina Borcezi ◽  
...  
Keyword(s):  
Secondary Phase ◽  
Linear Shrinkage ◽  
High Energy ◽  
Milling Process ◽  
Sintering Aids ◽  
X Ray Diffraction ◽  
Sintering Aid ◽  
Secondary Phase Formation ◽  
Precursor Powders ◽  
Perovskite Lattice

Precursor powders for BaCe0.2Zr0.7Y0.1O3-?(BCZY27) ceramics were synthesized by a modified Pechinimethod and calcined at 900?C for 12 h. The calcined BCZY27 powders were milled in eccentric and in high energy mill with the addition of 2 and 4mol% ZnO as sintering aid. The effects of milling and sintering aids on the sinterability and electrical conductivity were studied. The linear shrinkage in thermomechanical analyses started at 1050?C for the BCZY27 with 4mol% ZnO processed in eccentric mill. Theoretical density above of 90%TD was obtained for the BCZY27 milled with 4mol% ZnO and sintered at 1400?C for 4h. X-ray diffraction analysis of the BCZY27 ceramics sintered at 1400?C confirmed the presence of BaCe0.2Zr0.7Y0.1O3-? and Y0.4Ce0.6O1.8 phases. The incorporation of Zn into perovskite lattice leads to the secondary phase formation. SEM and EDS analyses confirmed the presence of Y0.4Ce0.6O1.8 phase. The sintering was assisted by BaO-ZnO eutectic, which was reflected by the increase of activation energy values for grain boundary conduction. The milling processing did not affect the conductivity properties. The obtained BCZY27 dense sample has conductivity of 7.60 ? 10?3 S/cm at 500?C.

Secondary phase formation by liquid immiscibility in Ca3Ta(Ga1−xAlx)3Si2O14 melt

2019 ◽  
Vol 522 ◽  
pp. 117-124
Author(s):  
Yuki Honda ◽  
Hiromasa Niinomi ◽  
Jun Nozawa ◽  
Junpei Okada ◽  
Satoshi Uda
Keyword(s):  
Phase Formation ◽  
Secondary Phase ◽  
Liquid Immiscibility ◽  
Secondary Phase Formation

Particular Oxydation Features of Various Mechanical Strength Cokes

2019 ◽  
Vol 946 ◽  
pp. 486-492
Author(s):  
V.I. Matyukhin ◽  
S.Ya. Zhuravlev ◽  
A.V. Khandoshka
Keyword(s):  
High Temperature ◽  
Heat Generation ◽  
Gas Permeability ◽  
Combustion Products ◽  
Charge Material ◽  
Reactivity Index ◽  
Generation Process ◽  
Charge Component ◽  
Scanning Calorimetry ◽  
Coke Strength

Lump solid fuel is one of the most important charge material components in layered cupola units. It determines layer gas permeability, conditions development for heat exchange with gasses in it, heat generation process rate and intensity. In present-day conditions of material shaft melting charge materials of boosted fractional makeup are used, as well as oxygen, carbon and hydrogen enriched air. In the circumstances the issue of ensuring the best gas dynamic conditions become particularly vital, both for the furnace low and high temperature zones, at the charge component oxidation and recovery processes development. Under conditions of continuous charge component movement in the layered unit workspace they are subjected to abrasive action of charge components with the result, which may be described by mechanical properties based on mass yield of certain fractions after disruption in a closed drum М10 and М40. Coke lump behavior at relatively high temperature (below 1100°С) in the presence of complete fuel combustion products СО2 and Н2О may be implicitly evaluated by coke strength after reaction (CSR) and coke reactivity index (CRI). When studying, particular combustion features of coal coke in conditions close to shaft cupola unit operation data of the total differential scanning calorimetry (DSC) curve were used. Temperature ranges of intensive heat generation were determined from the beginning of active coke sample oxidation to completion of the burnout period, as well as apparent heating capacity and coke combustion thermal effect.

scholarly journals Effects of Radiation Exposure on SRL 131 Composition Glass in a Steam Environment

1993 ◽  
Vol 333 ◽  
Author(s):  
D. J. Wronkiewicz ◽  
C. R. Bradley ◽  
J. K. Bates ◽  
L. M. Wang
Keyword(s):  
Radiation Exposure ◽  
Glass Surface ◽  
Average Rate ◽  
Reaction Times ◽  
Secondary Phase ◽  
Reaction Rates ◽  
Liquid Volume ◽  
Secondary Phase Formation ◽  
Effects Of Radiation ◽  
Doped Glass

ABSTRACTMonoliths of SRL 131 borosilicate glass were irradiated in a saturated air-steam environment, at temperatures of 150°C, to examine the effects of radiation on nuclear waste glass behavior. Half of the tests used actinide and Tc-99 doped glass and were exposed to an external ionizing gamma source, while the remaining glass samples were doped only with uranium and were reacted without any external radiation exposure. The effects of radiation exposure on glass alteration and secondary phase formation were determined by comparing the reaction rates and mineral paragenesis of the two sets of samples.All glass samples readily reacted with the water that condensed on their surfaces, producing two types of smectite clay within the first three days of testing. Additional crystalline phases precipitated on the altered glass surface with increasing reaction times, including zeolites, smectite, calcium and sodium silicates, phosphates, evaporitic salts, and uranyl silicates. Similar phases were produced on both the nonirradiated and irradiated samples; however, the quantity of precipitates was increased and the rate of paragenetic sequence development was accelerated in the latter. After 56 days of testing, the composite smectite layer developed at an average rate of ~0.16 and 0.63 µm/day for the nonirradiated and irradiated samples, respectively. These comparisons indicate that layer development is accelerated approximately four-fold due to the radiation exposure at high glass surface area/liquid volume (SA/V) conditions. This increase apparently occurs in response to the rapid concentration of radiolytic products, including nitric acid, in the thin films of water contacting the sample monoliths.

PH3 Effects on the Electrochemical Degradation of SOFC Anode

2011 ◽  
Author(s):  
Huang Guo ◽  
Gulfam Iqbal ◽  
Bruce S. Kang
Keyword(s):  
Electrochemical Performance ◽  
Secondary Phase ◽  
Anode Surface ◽  
Electrochemical Degradation ◽  
Secondary Phases ◽  
Nickel Phosphate ◽  
Secondary Phase Formation ◽  
Cell Anode ◽  
Fuel Cell Anode ◽  
Ppm Level

Solid Oxide Fuel Cell anode is readily degraded by trace amount of Phosphine (PH3) contaminant that is found in coal-derived syngas. PH3 interacts with the anode material and affects its electrochemical performance by forming secondary phases. In this paper, the influence of the ppm level of PH3 with moisture is investigated on the formation of secondary phases and hence on anode electrochemical performance degradation. Nickel yttria-stabilized zirconia (Ni-YSZ) anode shows immediate and severe electrochemical degradation due to PH3 in moist hydrogen condition attributed to the nickel-phosphate secondary phase formation. Whereas in dry hydrogen condition, nickel-phosphide is preferred to form on the anode surface that shows less deleterious effects on SOFC performance as compared to nickel-phosphate.

scholarly journals The Formation of Barite and Celestite through the Replacement of Gypsum

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 189 ◽  
Author(s):  
Pablo Forjanes ◽  
José Astilleros ◽  
Lurdes Fernández-Díaz
Keyword(s):  
Solid Solution ◽  
Fluid Phase ◽  
Secondary Phase ◽  
Crystal Habit ◽  
Replacement Reaction ◽  
Random Orientation ◽  
End Members ◽  
Kinetics Of ◽  
Oriented Layer ◽  
Orientational Relationship

Barite (BaSO4) and celestite (SrSO4) are the end-members of a nearly ideal solid solution. Most of the exploitable deposits of celestite occur associated with evaporitic sediments which consist of gypsum (CaSO4·2H2O) or anhydrite (CaSO4). Barite, despite having a broader geological distribution is rarely present in these deposits. In this work, we present an experimental study of the interaction between gypsum crystals and aqueous solutions that bear Sr or Ba. This interaction leads to the development of dissolution-crystallization reactions that result in the pseudomorphic replacement of the gypsum crystals by aggregates of celestite or barite, respectively. The monitoring of both replacement reactions shows that they take place at very different rates. Millimeter-sized gypsum crystals in contact with a 0.5 M SrCl2 solution are completely replaced by celestite aggregates in less than 1 day. In contrast, only a thin barite rim replaces gypsum after seven days of interaction of the latter with a 0.5 M BaCl2 solution. We interpret that this marked difference in the kinetics of the two replacement reactions relates the different orientational relationship that exists between the crystals of the two replacing phases and the gypsum substrate. This influence is further modulated by the specific crystal habit of each secondary phase. Thus, the formation of a thin oriented layer of platy barite crystals effectively armors the gypsum surface and prevents its interaction with the Ba-bearing solution, thereby strongly hindering the progress of the replacement reaction. In contrast, the random orientation of celestite crystals with respect to gypsum guarantees that a significant volume of porosity contained in the celestite layer is interconnected, facilitating the continuous communication between the gypsum surface and the fluid phase and guaranteeing the progress of the gypsum-by-celestite replacement.

Identification of Secondary Phases Formed During Unsaturated Reaction of UO2 with EJ-13 Water

1989 ◽  
Vol 176 ◽  
Author(s):  
J. K. Bates ◽  
B. S. Tani ◽  
E. Veleckis ◽  
O. J. Wronklewicz
Keyword(s):  
Phase Formation ◽  
Secondary Phase ◽  
Yucca Mountain ◽  
Solution Chemistry ◽  
Spent Fuel ◽  
Secondary Phases ◽  
Secondary Phase Formation

ABSTRACTA set of experiments, wherein UO2 has been contacted by dripping water, has been conducted over a period of 182.5 weeks. The experiments are being conducted to develop procedures to study spent fuel reaction under unsaturated conditions that are expected to exist over the lifetime of the proposed Yucca Mountain repository site. One half of the experiments have been terminated, while one half are ongoing. Analyses of solutions that have dripped from the reacted UO2 have been performed for all experiments, while reacted UO2 surfaces have been examined for the terminated experiments. A pulse of uranium release from the UO2 solid, combined with the formation of schoepite on the surface of the UO2, was observed between 39 and 96 weeks of reaction. Thereafter, the uranium release decreased and a second set of secondary phases was observed. The latter phases incorporated cations from the EJ-13 water and include boltwoodite, uranophane, sklodowskite, compreignacite, and schoepite. The experiments are continuing to monitor whether additional changes in solution chemistry or secondary phase formation occurs.

scholarly journals In situ observation of secondary phase formation in Fe implanted GaN annealed in low pressure N2 atmosphere

2009 ◽  
Vol 95 (23) ◽  
pp. 232506 ◽  
Author(s):  
G. Talut ◽  
J. Grenzer ◽  
H. Reuther ◽  
A. Shalimov ◽  
C. Baehtz ◽  
...  
Keyword(s):  
Phase Formation ◽  
Secondary Phase ◽  
Low Pressure ◽  
In Situ Observation ◽  
N2 Atmosphere ◽  
Secondary Phase Formation
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