743 J Mater Sci(2006)41:7425-7436 5000 Mi I{m-ZrO2(111+{t-ZrO2(111 ZrO2(111+I{-ZrO2(111+I{ ErIc4(200)} 27 2000 MUllite(210)1 IMullite(210))+IZrSio4(200)1 The results are summarized in Table 3. with a sub-micron zircon as starting powder, the reaction between zircon and alumina was much closer to completion than for the case of coar zIrcon Dow der. As shown in Fig. 12c, the rBM layer made fror RBAOTA finer zircon powder is composed of only mullite (matrix) and zirconia(brighter and in round shape) grains. From the XRD results, it has been found that up to 95 of the zircon was reacted to form mullite mated to be 93-95 TD% by comparing the results of X-ray phase analysis with the density measurements However, it should be noted that some glassy phase may be present in the rBM layers, which would not etected by XRD and would reduce the residual Fig 10(a) XRD powder patterns from a reaction-bonded porosity. aluminum oxide(RBAo)sample before and after reaction The above results show that we have successfully bonding:(b)optical micrograph of the cross-section of a RBAO/ fabricated three types of oxide ceramic laminates, TA laminate which were designed for different stress states and are micrograph of the cross- (b) section of a sintered alumina- toughened zirconia/textured alumina(ATZ/TA)laminate b) back scattering electron image of the ATZ layer; the atz layer; (d)Zr EDs map of the ATZ laye 2 SpringerM1 ¼ I mf gþ
ZrO2ð111Þ I t f g
ZrO2ð111Þ I mf gþ
ZrO2ð111Þ I t f gþ
ZrO2ð111Þ If g ZrSiO4ð200Þ ð6Þ M2 ¼ If g Mullite ð210Þ If g Mullite ð210Þ þ If g ZrSiO4ð200Þ ð7Þ The results are summarized in Table 3. With a sub-micron zircon as starting powder, the reaction between zircon and alumina was much closer to completion than for the case of coarse zircon pow￾der. As shown in Fig. 12c, the RBM layer made from finer zircon powder is composed of only mullite (matrix) and zirconia (brighter and in round shape) grains. From the XRD results, it has been found that up to 95% of the zircon was reacted to form mullite and zirconia. The final laminate density was esti￾mated to be 93–95 TD% by comparing the results of X-ray phase analysis with the density measurements. However, it should be noted that some glassy phase may be present in the RBM layers, which would not be detected by XRD and would reduce the residual porosity. The above results show that we have successfully fabricated three types of oxide ceramic laminates, which were designed for different stress states and are Fig. 11 (a) Optical micrograph of the cross￾section of a sintered alumina￾toughened zirconia/textured alumina (ATZ/TA) laminate; (b) back scattering electron image of the ATZ layer; (c) Al energy dispersive X-ray spectroscopy (EDS) map of the ATZ layer; (d) Zr EDS map of the ATZ layer 0 1000 2000 3000 4000 5000 30 40 50 60 70 80 90 RBAO20/green RBAO/final Intensity (a.u.) 2θ(degree) (a) (b) Fig. 10 (a) XRD powder patterns from a reaction-bonded aluminum oxide (RBAO) sample before and after reaction bonding; (b) optical micrograph of the cross-section of a RBAO/ TA laminate 7434 J Mater Sci (2006) 41:7425–7436 123