September 2003 Wear Behavior of Al/Al-Zr Laminated Composites 1549 Log(Velocity, m/s) 1.00 Ball on Flat 5.22 lumina on alumina Ho=16.616.6GPa Ra=6.00 To=25°C a=13.613.6mm2/s uo=0.90c1=250.0 L1b= 10.0 L2b= arctan x 四乏u T3 T4 T5 T6 50050505 T8 5.00 H-0.77 Log(Normalized Velocity) 5.00 Fig. 2. Ashby map with the points relative to the test conditions. Ball-on-flat has been selected because pin-on-disk tests using pins with a spherical end can be approximated to that configuration. The symbol O refers to material A/AZ while symbol to AA and symbol V to MA. Il. Results and Discussion Table 1. Mean Values of Grain Size for the Three Different Materials Produced (1) Microstructural Properties For A/AZ hybrid laminates, the mean density was 4.16= 0.0 Mean grain Material 'cm and for AA laminates it was 3. 88+ 0.02 g/cm(96.8% and size (um) 97.3% of the theoretical density, respectively ) For the material MA, the density almost reached theoretical level. Due to the high amount of organic substances used in tape casting, a small amount Alumina in a/AZ of porosity in sintered bodies obtained by this process4..2 is to Alumina laver A be expected. This porosity was almost equally distributed through Composite layer AZ. out the layers. Zirconia (in AZ layer) in hybrid laminate A/AZ 0.35 Figure 3 shows a micrograph of the cross section of the A/AZ aminated structure. Table I shows the mean grain size values measured in the different materials It is evident from Table I that the highest temperature used sInter nolithic alumina results in the formation of slight In the hybrid laminates, the growth of alumina grains in the AZ layers is hindered by the zirconia, as expected. (2) Mechanical Properties and Residual Stresses Calculation Table II shows Vickers hardness values, calculated Y oung s moduli, and fracture toughnesses of the different materials 因射 Table Il. Measured Hardness, Calculated Youngs Modulus, and Surface Toughness for the Different Materials N额的 Material HV (GP: E(GPa K,(MPam)' A/AZ 17.6±0.8 5.37±0.502 164±0.6 3.04±0.2 16.6±0.5 410 3.35±0.43 400 (361 Fig- 3, Optical microscope photograph of a cross section of the hybrid laminate A/AZ. The darker layers are alumina, while the lighter ones are niques for aw an moina with similar microstructure. 31Refemed to alumina layers already re the composite alumina-zirconia