Enhanced mechanical properties by grain boundary strengthening in ultra-fine-grained TZP ceramics

Abstract

The mechanical properties of ceramics with the compositions of 5 mol% YO,.s-TZP (ZY5) and 4 mol% YOl.i-4 mol% CeO,-TZP (ZY4Ce4) were investigated. Nanocrystalline powders of both TZPs were synthesized by a gel precipitation technique. Powder compacts were made by cold isostatic pressing, and were then pressureless sintered or sinter-forged to dense TZP ceramics (density: 9699%) with grain sizes of 180 nm. Shear deformation during sinter-forging was found to favourably afleet densification and microstructure. The mechanical properties of both types of ultrafine-grained TZP ceramics were examined up to 760°C. The results point towards an improved grain boundary structure and the elimination of residual flaws obtained by the sinter-forging technique. The sinter-forged samples exhibited a higher Vicker hardness compared to that of pressureless sintered specimens. After sin ter-forging the fracture energy value was found to be 325 J/m2 and the fracture toughness to be IO MPa ml". A Weibull modulus of 21 was obtained for the sinter-forged samples which was sigm$cantly higher than the value of 8 for the pressureless sintered specimens. The enhancement of reliability is obviously connected to a decrease in the average size and concentration of flaws caused by inhomogeneous powder particle packing due to the presence of irregular agglomerates.

An investigation of different ceramic coating thermal properties

“…Latest works expose that microstructure and mechanical properties, such as grain size [12][13][14][15][16], porosity [17], hardness [18,19], fracture toughness [20], have strong effect on abrasive/sliding wear resistance of bulk ceramics and coatings under dry or lubrication circumstances. Among the reduction in the grain size of ceramics, their mechanical properties would be improved [21,22], which is helpful in improving the abrasive/sliding wear resistance of bulk ceramics and coatings [1,18,[12][13][14][15][16][17][18][19][23][24][25].…”

Effect of density homogeneity on the dynamic response of powder beds

“…The properties and quality of particulate products are de-Ž pendent upon the means of processing He et al, 1996;Lu et . al., 2000;Yeh et al, 1988;Zhao et al, 1988 .…”

­Effect of sintering treatment time on the sintering behaviour and thermal shock resistance of Li2O-Al2O3-SiO2 glass-ceramics

“…Meanwhile, LAS glass-ceramics doped with B 2 O 3 , Na 3 AlF 6 and Na 2 O and thermally treated at 630-835°C for 2 h, yielded 2.74 × 10 −6°C−1 CTE (100-650°C) with 132.4 MPa flexural strength [56]. Apart from that, other studies favored smaller grain size as it enhances the mechanical properties [35,57]. This may also be explained by the fact that large grain size is susceptible to destructive mechanical strength causing higher CTE, making the appearance of microcracks perceivable [32,56,58].…”