In mortar and concrete, the microstructure of the cement paste is affected by the presence of the aggregate and sand particles and this is most significant in the interfacial transition zone (ITZ). The durability of concrete is affected by the inferior proportion of constituents in ITZ compared with bulk paste, i.e. higher porosity, higher calcium hydroxide (CH), lower calcium silicate hydroxide (C-S-H), and almost no anhydrous in ITZ. This work for the first time investigates the effect of sand size on the proportion of different constituents in ITZ and mortar as a whole. It shows that, as sand size reduces, the shearing force exerted on the paste during mixing increases leading to an increase in C-S-H/CH ratio. Also the effective w/c ratios in the ITZs are calculated for different sand sizes. It is shown that water/cement (w/c) ratio increases with sand size and decreases with distance from the sand surface.

Abstract Precipitates were induced by aging super-saturated (Zr,W)C solid solution carbides. The temperature dependence of their solubility was analyzed, as were their mechanical properties (hardness and toughness). The solubility limit of WC in the (Zr,W)C was 0.15 ± 0.03 mol fraction at 1500 °C and 0.27 ± 0.03 mol fraction at 1850 °C. The aged (Zr0.7W0.3)C ceramics were significantly strengthened up to 8 MPa m1/2 compared with the as-sintered (Zr0.7W0.3)C.

The parameters for the electroplating process of Ni-Fe(Ti,W)C nanocomposite on the steel substrate were developed and optimised. for this purpose, the coating process was performed under a direct current using a nickel bath. The coating was fully characterised employing the X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy and microhardness tester. The results indicated that the Ni-Fe(Ti,W)C nanocomposite can be coated on the steel with an appropriate structure using the current density and the concentration of 40 mA cm(-2) and 6 g L-1, respectively.

Partially solutionized carbide cermets (PSCs) were prepared for cutting tool applications by replacing a portion of Ti(CN) with (Ti0.88W0.12) C or (Ti0.88W0.12)(C0.7N0.3) in a conventional Ti(CN)-based cermet. The PSC containing (Ti0.88W0.12) C exhibited high fracture toughness with no loss of hardness. The elimination of Ti(C0.7N0.3) cores in the microstructure reduced the strain at the core/rim interfaces, leading to the increase in fracture toughness. The PSC containing (Ti0.88W0.12) C showed coherent relationships at the core/rim and rim/binder interfaces, contributing to the improved mechanical properties. In contrast, nitrogen in (Ti0.88W0.12)(C0.7N0.3) resulted in a different microstructure and properties. The major factors determining the mechanical properties of the cermets are discussed in terms of the carbide/binder interfaces and the thermal stability of the added carbides. (C) 2015 Elsevier B.V. All rights reserved.

Highlights • The addition of (Ti0.88W0.12)C significantly improved the toughness of cermets. • The ceramic particles in the cermets exhibited {111} plane faceting. • The coherency state at the core/rim/binder interfaces led to high toughness. • The thermal stability of constituents and nitrogen in the system are the main causes. Abstract Partially solutionized carbide cermets (PSCs) were prepared for cutting tool applications by replacing a portion of Ti(CN) with (Ti0.88W0.12)C or (Ti0.88W0.12)(C0.7N0.3) in a conventional Ti(CN)-based cermet. The PSC containing (Ti0.88W0.12)C exhibited high fracture toughness with no loss of hardness. The elimination of Ti(C0.7N0.3) cores in the microstructure reduced the strain at the core/rim interfaces, leading to the increase in fracture toughness. The PSC containing (Ti0.88W0.12)C showed coherent relationships at the core/rim and rim/binder interfaces, contributing to the improved mechanical properties. In contrast, nitrogen in (Ti0.88W0.12)(C0.7N0.3) resulted in a different microstructure and properties. The major factors determining the mechanical properties of the cermets are discussed in terms of the carbide/binder interfaces and the thermal stability of the added carbides. Graphical abstract

New relations for the Appell function F-4(a, b; c, c'; w, z) are obtained including differentiation and integration formulas, finite and infinite series, and functional relations. Some reduction and transformation formulas are also presented.

Highlights • For the first time, the C–W–Zr ternary system is described using the CALPHAD approach. • Experimental phase diagram data over the whole temperature and composition range are well reproduced by this modeling. • The complete liquidus projection, three-dimensional isometric view, and reaction scheme of the C–W–Zr system are presented. Abstract On the basis of critical evaluation of the literature data, the ternary C–W–Zr phase diagram has been assessed by means of the CALPHAD technique. The individual solution phases, i.e., liquid, fcc, hcp, bcc, and W2Zr have been modeled. The modeling covers the whole composition and temperature ranges. A self-consistent thermodynamic description for the C–W–Zr system has been developed. Comprehensive comparisons between the present calculations and measured phase diagrams show that the reliable experimental information is satisfactorily accounted for by the present thermodynamic description. The liquidus projection, three-dimensional isometric view, and reaction scheme of the C–W–Zr system have been presented.

Highlights • Effect of W fraction on pressureless densification of W–Si–C composites. • Full densification of high-W composite in a single PIP cycle. • High-W composite exhibits increase in thermal conductivity with temperature. • Low-W composites densified with six PIP cycles. • Low-W composites exhibit high mechanical and thermal properties. Abstract W–Si–C composites were fabricated by active filler controlled pyrolysis of W powder (high tungsten content) and W–SiC powder mixtures (low tungsten content), infiltrated by a preceramic polymer and heat treated at temperatures from 1600 to 2000 °C. Material with high volume fraction of W in initial powder–polymer mixture, formed a composite material composed of W, W2C and W5Si3 with closed porosity in a single polymer infiltration and pyrolysis (PIP) cycle. After heat treatment at 1700 °C the material exhibited flexural strength above 350 MPa, hardness of 7.8 GPa and indentation modulus of 250 GPa. Room temperature thermal conductivity of the composite was rather low, 23 W m−1 K−1, however, thermal conductivity increased with increasing temperature achieving 35 W m−1 K−1 at 1000 °C. The effect of W as active filler in W–SiC powder mixtures with low volume fraction of tungsten was negligible. Therefore, six polymer infiltration and pyrolysis cycles were used to achieve significant densification with 15% porosity. The material fabricated at 1800 °C was composed of SiC, WC and WSi2 and exhibited flexural strength of ∼400 MPa and room temperature thermal conductivity of 100 W m−1 K−1, which decreased to 32 W m−1 K−1 at 1000 °C. Graphical abstract

The parameters for the electroplating process of Ni-Fe(Ti,W)C nanocomposite on the steel substrate were developed and optimised. for this purpose, the coating process was performed under a direct current using a nickel bath. The coating was fully characterised employing the X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy and microhardness tester. The results indicated that the Ni-Fe(Ti,W)C nanocomposite can be coated on the steel with an appropriate structure using the current density and the concentration of 40 mA cm−2 and 6 g L−1, respectively.