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Milti-principal cation oxide ceramics with excellent mechanical properties for potential applications in coating materials. A Multi-principal cation mullite (MPCM) ceramic is synthesized with MgO, TiO 2 , Cr 2 O 3 , ZrCl 2 O·8H 2 O and Al 2 O 3 , SiO 2 via solid state reaction at 1600 °C. It is determined that 96.9 % of the sample composition is mullite. MPCM ceramic exhibits higher compressive strength (981 ± 19 MPa) and fracture toughness (3.37 ± 0.05 MPa∙m1/2), the compressive strength has raised by 453 MPa, and the added value of solution strengthening (452 MPa) is gained by using solid-solution strengthening theory. The improvement of compressive strength is mainly due to the solution strengthening effect of the four oxides(Mg, Ti, Zr, Cr), and the improvement of fracture toughness is caused by the grain hindrance during crack propagation. Moreover, its application at the high-temperature resistant coating is verified through experimentation. The interfacial binding force, as an important mechanical property index for ceramics, is researched. In this study, pure mullite powder and MPCM powder are coated onto the refractory TaWNbV alloy matrix by slurry coating method, and the interfacial toughness of the two coatings mingled with the matrix is calculated to be 72.9 and 62.6 J·m−2, respectively. The "shrinking cylinder" model is introduced to interpret the oxidative weight gain mechanism of the two coatings. [ABSTRACT FROM AUTHOR]

In this study, W-MeC-Si/PCD (Me = Ti, Zr, Hf, V, Nb and Ta) composite materials were prepared via high pressure and high temperature (HPHT, 5.5 GPa and 1600 °C) sintering, the effect of the addition of transition metal carbides on the micromorphology, phase composition and mechanical properties of PCD has been systematically studied, and various mechanical data of W-TaC-Si/PCD have been provided. The results show that the addition of MeC is conducive to the improvement of the mechanical properties of PCD. The sample with TaC has the best mechanical properties, and its flexural strength, relative density, hardness and fracture toughness reached 743.5 MPa, 99.75%, 63.4 GPa and 8.1 MPa m1/2, respectively. Finally, the toughening mechanism of W-MeC-Si/PCD is also discussed. The improvement of fracture toughness can be attributed to the change of fracture mode and the pinning effect of MeC dispersion in the binder. [ABSTRACT FROM AUTHOR]

ZTM ceramics were successfully derived from coal gangue. The effect of zirconium source (ZrO 2 and ZrOCl 2 ∙8H 2 O) and content on properties of the ZTM ceramics has been studied. The phase composition, density, and microscopic morphology were characterized with X-ray diffraction (XRD), Archimedes method and scanning electron microscopy (SEM). The influence of zirconium source, sintering temperature, zirconia content on flexural properties and fracture toughness was studied. The sample, with ZrOCl 2 ∙8H 2 O added 12% zirconia (Z2TM12) sintered at 1475 °C for 3 h has the highest density of 2.83 g/cm3. Partially stable t -ZrO 2 was present in samples with zirconium oxychloride (ZrOCl 2 ∙8H 2 O) as the zirconium source, due to the constraints of mullite crystals. Therefore, Z2TM12 had both microcrack toughening and stress phase transformation toughening mechanisms. The flexural strength was increased from 162.40 MPa to 285.04 MPa, while the fracture toughness was improved to 3.55 MPa m1/2 from 2.38 MPa m1/2. Our achievement can be used as a reference to fabricate ZTM ceramics from coal gangue with high-value additions. [ABSTRACT FROM AUTHOR]