In the present work, the effect of Zr-doping on the sintering, microstructure development, and mechanical properties of polycrystalline Al2O3 was studied. Dopant concentrations of 830 and 2070ppm cationic ratio of Zr in Al2O3 corresponding to 2000 and 5000 wt. ppm of ZrO2 in Al2O3, respectively, were used. The sintering schedule of undoped as well as Zr-doped Al2O3 samples was optimised following a series of precoarsening experiments. The Zr-doped Al2O3 ceramics exhibited controlled grain size and improved density. Upon increasing the Zr-dopant concentration from 830 cat. ppm to 2070 cat. ppm. Zr-doped Al2O3 ceramics having a refined microstructure with a homogeneous distribution of controllably grown ZrO2 in Al2O3 matrix was obtained. Microhardness of the Zr-doped samples showed negligible dependence with Zr-doping, whereas mechanical strength was found to improve with it. The improvement in strength was attributed to the combined effect of improved sinter density, microstructural refinement, and grain-boundary strengthening.
RileyF.Structural ceramics. Cambridge: Cambridge University Press; 2009.
2.
ChoJ, HarmerM, ChanHM, . Effect of yttrium and lanthanum on the tensile creep behavior of aluminum oxide. J Am Ceram Soc. 1997;80:1013–1017. doi:10.1111/j.1151-2916.1997.tb02936.x
3.
SkrovanekSD, BradtR.Microhardness of a fine-grain-size Al2O3. J Am Ceram Soc. 1979;62(3-4):215–216. doi:10.1111/j.1151-2916.1979.tb19059.x
4.
RiceR.Ceramic tensile strength-grain size relations: grain sizes, slopes, and branch intersections. J Mater Sci. 1997;32(7):1673–1692. doi:10.1023/A:1018511613779
5.
RoyRS, GuchhaitH, ChandaA, . Improved sliding wear-resistance of alumina with sub-micron grain size: a comparison with coarser grained material. J Eur Ceram Soc. 2007;27(16):4737–4743. doi:10.1016/j.jeurceramsoc.2007.02.205
6.
MuchtarA, LimL.Indentation fracture toughness of high purity submicron alumina. Acta Mater. 1998;46(5):1683–1690. doi:10.1016/S1359-6454(97)00371-6
7.
KrellA, BlankP, MaH, . Processing of high-density submicrometer Al2O3 for new applications. J Am Ceram Soc. 2003;86(4):546–553. doi:10.1111/j.1151-2916.2003.tb03339.x
8.
GaoL, HongJ, MiyamotoH, . Bending strength and microstructure of Al2O3 ceramics densified by spark plasma sintering. J Eur Ceram Soc. 2000;20(12):2149–2152. doi:10.1016/S0955-2219(00)00086-8
9.
ChakravartyD, BysakhS, MuraleedharanK, . Spark plasma sintering of magnesia-doped alumina with high hardness and fracture toughness. J Am Ceram Soc. 2008;91(1):203–208. doi:10.1111/j.1551-2916.2007.02094.x
10.
WeibelA, BouchetR, DenoyelR, . Hot pressing of nanocrystalline TiO2 (anatase) ceramics with controlled microstructure. J Eur Ceram Soc. 2007;27(7):2641–2646. doi:10.1016/j.jeurceramsoc.2006.11.073
11.
HeZ, MaJ.Grain-growth rate constant of hot-pressed alumina ceramics. Mater Lett. 2000;44(1):14–18. doi:10.1016/S0167-577X(99)00289-X
12.
LinFJ, JongheLC, RahamanMN.Microstructure refinement of sintered alumina by a Two-step sintering technique. J Am Ceram Soc. 1997;80(9):2269–2277. doi:10.1111/j.1151-2916.1997.tb03117.x
13.
KrellA, KlaffkeD.Effects of grain size and humidity on fretting wear in fine-grained alumina, Al2O3/TiC, and zirconia. J Am Ceram Soc. 1996;79(5):1139–1146. doi:10.1111/j.1151-2916.1996.tb08565.x
14.
KrellA, BlankP.Grain size dependence of hardness in dense submicrometer alumina. J Am Ceram Soc. 1995;78(4):1118–1120. doi:10.1111/j.1151-2916.1995.tb08452.x
15.
KrellA, BlankP.The influence of shaping method on the grain size dependence of strength in dense submicrometre alumina. J Eur Ceram Soc. 1996;16(11):1189–1200. doi:10.1016/0955-2219(96)00044-1
16.
KooJ, HongK, ParkJ, . Effect of grain size on transmittance and mechanical strength of sintered alumina. Mater Sci Eng A. 2004;374(1):191–195.
17.
GalusekD, GhillányováK, SedláčekJ, . The influence of additives on microstrucutre of sub-micron alumina ceramics prepared by two-stage sintering. J Eur Ceram Soc. 2012;32(9):1965–1970. doi:10.1016/j.jeurceramsoc.2011.11.038
18.
ChoJ, WangCM, ChanHM, . Role of segregating dopants on the improved creep resistance of aluminum oxide. Acta Mater. 1999;47(15):4197–4207. doi:10.1016/S1359-6454(99)00278-5
19.
BeheraSK.Kinetics of grain growth in La-doped ultrapure Al2O3. J Alloys Compd. 2016;683:444–449. doi:10.1016/j.jallcom.2016.05.109
20.
FrankenPEC, GehringAP.Grain boundary analysis of MgO-doped Al2O3. J Mater Sci. 1981;16(2):384–388. doi:10.1007/BF00738627
BeheraSK, CantwellPR, HarmerMP.A grain boundary mobility discontinuity in reactive element Zr-doped Al2O3. Scr Mater. 2014;90-91:33–36. doi:10.1016/j.scriptamat.2014.07.010
23.
WakaiF, NaganoT, IgaT.Hardening in creep of alumina by zirconium segregation at the grain boundary. J Am Ceram Soc. 1997;80(9):2361–2366. doi:10.1111/j.1151-2916.1997.tb03128.x
24.
IkuharaY, YoshidaH, SakumaT.Impurity effects on grain boundary strength in structural ceramics. Mater Sci Eng A. 2001;319-321:24–30. doi:10.1016/S0921-5093(01)01035-8
25.
YoshidaH, OkadaK, IkuharaY, . Improvement of high-temperature creep resistance in fine-grained Al2O3 by Zr4+ segregation in grain boundaries. Philos Mag Lett. 1997;76(1):9–14. doi:10.1080/095008397179327
26.
KingeryWD.Structure and properties of MgO and Al2O3 ceramics. Am Ceram Soc. 1984;10.
27.
BaruahB, AnandR, BeheraSK.Master sintering curve and activation energy of sintering of ZrO2-doped Al2O3. Ceram Int. 2021;47(5):7253–7257. doi:10.1016/j.ceramint.2020.11.001
28.
GreenDJ.Critical microstructures for microcracking in Al2O3-ZrO2 composites. J Am Ceram Soc. 1982;65(12):610–614. doi:10.1111/j.1151-2916.1982.tb09939.x
29.
AksayI, LangeF, DavisB.Uniformity of Al2O3-ZrO2 composites by colloidal filtration. J Am Ceram Soc. 1983;66(10):c190–c192. doi:10.1111/j.1151-2916.1983.tb10550.x
30.
BalmerML, LangeFF, JayaramV, . Development of nano-composite microstructures in ZrO2-Al2O3 via the solution precursor method. J Am Ceram Soc. 1995;78(6):1489–1494. doi:10.1111/j.1151-2916.1995.tb08842.x
31.
LangeF, HirlingerMM.Hindrance of grain growth in Al2O3 by ZrO2 inclusions. J Am Ceram Soc. 1984;67(3):164–168. doi:10.1111/j.1151-2916.1984.tb19734.x
32.
HeH, ZhaoR, TianH, . Sintering behavior of alumina whisker reinforced zirconia ceramics in hot oscillatory pressing. J Adv Ceram. 2022;11(6):893–900. doi:10.1007/s40145-022-0583-5
33.
JiaY, SuX, WuY, . Flash sintering of 3YSZ/Al2O3-platelet composites. J Am Ceram Soc. 2020;103(4):2351–2361. doi:10.1111/jace.16929
34.
LallemantL, RousselN, FantozziG, . Effect of amount of doping agent on sintering, microstructure and optical properties of Zr- and La-doped alumina sintered by SPS. J Eur Ceram Soc. 2014;34(5):1279–1288. doi:10.1016/j.jeurceramsoc.2013.11.015
35.
HouPY.Impurity effects on alumina scale growth. J Am Ceram Soc. 2003;86(4):660–668. doi:10.1111/j.1151-2916.2003.tb03355.x
36.
ProcopioA, ZavaliangosA, CunninghamJ.Analysis of the diametrical compression test and the applicability to plastically deforming materials. J Mater Sci. 2003;38(17):3629–3639. doi:10.1023/A:1025681432260
37.
C. ASTM. (2003). 1499-03. Standard test method for monotonic equibiaxial flexural strength of advanced ceramics at ambient temperature. West Conshohocken, Pennsylvania: ASTM International.
38.
SatoE, CarryC.Effect of powder granulometry and pre-treatment on sintering behavior of submicron-grained α-alumina. J Eur Ceram Soc. 1995;15(1):9–16. doi:10.1016/0955-2219(95)91294-X
39.
WestmacottK, FountainC, StirtonR.On the spacing of dispersed obstacles. Acta Metall. 1966;14(11):1628–1629. doi:10.1016/0001-6160(66)90184-2
40.
KocksU.On the spacing of dispersed obstacles. Acta Metall. 1966;14(11):1629–1631. doi:10.1016/0001-6160(66)90185-4
41.
AnandR, NayakBB, BeheraSK.Coarsening kinetics of nanostructured ZrO2 in Zr-doped SiCN ceramic hybrids. J Alloys Compd. 2019;811:151939. doi:10.1016/j.jallcom.2019.151939
ChantikulP, BennisonSJ, LawnBR.Role of grain size in the strength and R-curve properties of alumina. J Am Ceram Soc. 1990;73(8):2419–2427. doi:10.1111/j.1151-2916.1990.tb07607.x
44.
TuanWH, ChenJR, YangTJ.Minimum amount of nano-sized nickel particles to enhance the strength of alumina. J Eur Ceram Soc. 2007;27(16):4705–4709. doi:10.1016/j.jeurceramsoc.2007.03.033
