The liquidus surface in SiC–B4C–Me
 d
 B2 quasi-ternary eutectic systems (where Me
 d
 B2 is CrB2, VB2, NbB2, TaB2, ZrB2, HfB2, and W2B5) is modeled in the approximation of the regular solution model based on the experimental data on bordering systems and individual compounds. The calculated and experimental data are compared. Regularities of the structure of phase diagrams of SiC–B4C–Me
 d
 B2 systems are analyzed. It is noted that the diboride concentration appropriately decreases in the triple eutectic with an increase in its melting point. Correlation dependences between the eutectic temperature and melting point $${t_{eut}} = f\left( {t_m^{M{e^d}{B_2}}} \right)$$
 and formation enthalpy of diboride $${t_{eut}} = f\left( {\vartriangle H_f^{M{e^d}{B_2}}} \right)$$
 are constructed. The character of dependences is close to previously observed similar dependences in SiC–Me
 d
 B2 and B4C–Me
 d
 B2 bordering quasi-binary systems. It is concluded based on the analysis of the structure and parameters of analyzed systems that it is promising to develop a broad series of construction and functional ceramic materials and coatings fabricated by “free” sintering and by pulsed methods of heating and consolidation based on the considered systems.

Revisiting the structure of SiC–B 4 C–Me d B 2 systems and prospects for the development of composite ceramic materials based on them

Semi-empirical balance-based computational model of air-cooled condensers with the A-frame layout

Arsenic immobilization from aqueous solution by the precipitation of the pseudo-octahedral arsenate-substituted natroalunite solid solutions.

On-site investigations show that an asynchronous load feature would greatly influence the operation of water systems for centralized air conditioning. However, the manner of defining the load feature and relating it to its influence quantitatively is still unclear. This article quantitatively describes the asynchronous load demand feature and reveals its relationship with the loss of pump power and heat transfer ability in a centralized air-conditioning water system. The Lorenz curve and the Gini index are introduced in this study and used as indices to depict load features. For a large-scale use in office buildings, shopping malls, and other buildings, the fan coil unit and the variable air volume systems are investigated in this study. The loss of pump power on valves and heat transfer ability under different load profiles are analyzed. This study develops a new perspective of analyzing load patterns and quantitatively explores reasons for the resulting losses in pump power and heat transfer ability in ...

Influence of load feature on the water distribution system in a centralized air-conditioning system

A high-density ceramic material (97% of theoretical density) was obtained by hot pressing of ball-milled powders W2B5, ZrB2, SiC and B4C with holding for 15 minutes at a temperature of 1850°C and a pressure of 30 MPa in an argon atmosphere. The structure and composition of the material were investigated by x-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Vickers hardness (19.3 GPa), crack resistance coefficient (5,7 MPa∙m1/2) and bending strength (695 MPa) were determined.

Structure and Mechanical Properties of Hot-Pressed Composite Ceramics W2B5–ZrB2–SiC–B4C

Strong electric fields can accelerate molecular dissociation reactions. The phenomenon known as the Wien effect was previously observed using high-voltage electrolysis cells that produced fields of about 107 V m-1, sufficient to accelerate the dissociation of weakly bound molecules (e.g., organics and weak electrolytes). The observation of the Wien effect for the common case of water dissociation (H2O [Formula: see text] H+ + OH-) has remained elusive. Here we study the dissociation of interfacial water adjacent to proton-permeable graphene electrodes and observe strong acceleration of the reaction in fields reaching above 108 V m-1. The use of graphene electrodes allows measuring the proton currents arising exclusively from the dissociation of interfacial water, while the electric field driving the reaction is monitored through the carrier density induced in graphene by the same field. The observed exponential increase in proton currents is in quantitative agreement with Onsager's theory. Our results also demonstrate that graphene electrodes can be valuable for the investigation of various interfacial phenomena involving proton transport. 

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Wien effect in interfacial water dissociation through proton-permeable graphene electrodes

B4C–ZrB2–SiC composites were synthesised by arc melting in Ar atmosphere using B4C, ZrB2 and β-SiC powders as starting materials. The ternary eutectic composition of 40B4C–20ZrB2–40SiC (mol-%) was first identified and a lamellar eutectic texture was observed. SiC and ZrB2 grains about 1 μm in thickness were uniformly dispersed in B4C matrix of B4C–ZrB2–SiC eutectic composite. B4C (003) and ZrB2 (100) planes were perpendicular to the growth direction. The Vickers hardness of B4C–ZrB2–SiC ternary eutectic composite was 30–34 GPa. The fracture toughness of B4C–ZrB2–SiC composite increased with the decrease of B4C content and the rise of ZrB2 content.

Preparation of B4C–ZrB2–SiC ternary eutectic composites by arc melting and their properties

GdBa2Cu3O7−δ (GdBCO or Gd123) ceramics have been successfully prepared at oxygen partial pressure () of 0.02–0.10 MPa via solid state reaction method by using Gd2O3, BaCO3 and CuO powders as raw materials, whereas GdBa2Cu3O7−δ decomposed to Gd2BaCuO5 (Gd211), Gd2O3 and barium copper oxides owing to the instability of GdBa2Cu3O7−δ at according to the stability phase diagram of GdBa2Cu3O7−δ. Effect of on the phase structure and microstructure of GdBa2Cu3O7−δ has been investigated by X-ray diffractometer and field-emission scanning electron microscopy methods. Composition and microstructure of pellets sintered at were totally different from pellets sintered at .

S. Zhang

Papers

Wien effect in interfacial water dissociation through proton-permeable graphene electrodes

Preparation of B4C–ZrB2–SiC ternary eutectic composites by arc melting and their properties

Effect of oxygen partial pressure on the composition and structure of GdBa2Cu3O7−δ by solid state reaction