Preparation of Y₂Si₂O₇/ZrO₂ Composites and Their Composition – Mechanical Properties – Tribology Relationships

Abstract

In this work, novel Y2Si2O7/ZrO2 composites were developed for structural and coating applications by taking advantage of their unique properties, such as good damage tolerance, tunable mechanical properties, and superior wear resistance. The γ‐Y2Si2O7/ZrO2 composites showed improved mechanical properties compared to the γ‐Y2Si2O7 matrix material, that is, the Young's modulus was enhanced from 155 to 188 GPa (121%) and the flexural strength from 135 to 254 MPa (181%); when the amount of ZrO2 was increased from 0 to 50 vol%, the γ‐Y2Si2O7/ZrO2 composites also presented relatively high facture toughness (>1.7 MPa·m1/2), but this exhibited an inverse relationship with the ZrO2 content. The composition–mechanical property–tribology relationships of the Y2Si2O7/ZrO2 composites were elucidated. The wear resistance of the composites is not only influenced by the applied load, hardness, strength, toughness, and rigidity but also effectively depends on micromechanical stability properties of the microstructures. The easy growth of subcritical microcracks in Y2Si2O7 grains and at grain boundaries significantly contributes to the macroscopic fracture toughness, but promotes the pull‐out of individual grains, thus resulting in a lack of correlation between the wear rate and the macroscopic fracture toughness of the composites.

Lifetime of environmental/thermal barrier coatings deposited on a niobium silicide composite with boron containing M7Si6‐based bond coat

“…The adhesion of the Y 2 SiO 5 layer to both the TGO and the GZO topcoat was good, probably related to compatible CTE values. For yttrium monosilicate CTE values of (5–8) × 10 −6 K −1 were determined , quite matching those of GZO, chromia and MASC substrate given above. The yttrium silicate layer seems to reduce the localized degradation of the B‐containing M 7 Si 6 ‐based bond coat at the edges of the MASC coupons.…”

Recent progress on synthesis, multi-scale structure, and properties of Y–Si–O oxides

“…162 Thus, wear characteristics in different environments need to be well understood. Sun et al 163 To improve the mechanical and tribological properties of c-Y 2 Si 2 O 7 , Sun et al 164 developed a series of Y 2 Si 2 O 7 / ZrO 2 composites, which are promising as protective coatings against thermal loads and chemical attack. 165 Compared to c-Y 2 Si 2 O 7 , c-Y 2 Si 2 O 7 /ZrO 2 composites showed improved mechanical properties, e.g.…”

Theoretical Predictions on Elastic Stiffness and Intrinsic Thermal Conductivities of Yttrium Silicates

“…Experimental trials have proved that yttrium silicates are promising candidates for environmental/thermal barrier coatings (ETBC) due to their unique mechanical/thermal properties and superior environmental durability . Recent research also revealed that Y 2 Si 2 O 7 /ZrO 2 composite with improved mechanical properties and wear resistance is candidate for advanced ETBC against thermal load, chemical attack, and humid hot‐gas corrosion . In Sun's work, bulk γ‐Y 2 Si 2 O 7 and Y 2 SiO 5 samples have been processed via pressureless sintering and the thermal conductivity was obtained by measuring thermal diffusivity, heat capacity, and density.…”