Sintering of alumina ceramics under different sintering pressure
Shandong Avant New Material Technology studied the effect of oscillation pressure on sintering behavior and mechanical properties of alumina ceramics in different sintering stages through an experiment.
Compared with the traditional ceramic made by hot pressing, the ceramic made by hot shaking hot pressing has higher density, smaller grain size, higher hardness and fracture strength.
The oscillation pressure is beneficial to improve the sintering behavior of alumina ceramics, which is independent of sintering steps. In addition, the higher the temperature at which the oscillating pressure is applied, the better the mechanical properties of the ceramic, and therefore the better the performance of the ceramic.
Experimental materials:
In the experiment, α -Al2O3 powder with particle size D50 of 0.17 μm, purity of 99.99% and surface area of 14.5 m2/g was selected. The powder was used without sintering additives.
Experimental method:
The powder was placed into a graphite mold with an inner diameter of 60 mm and sintered in a hot shaking press furnace. Five sets of samples were prepared under different processing conditions.
The first was prepared by conventional HP, where the temperature was first increased to 900 °C and held for 60 minutes, then increased to 1100 °C and held for 60 minutes, and finally increased to 1300 °C, and then the samples were cooled to room temperature in an oven. During the high pressure process, when the temperature reached 900 °C, a static uniaxial pressure of 40 MPa was applied and maintained until the end of sintering.
The second, third and fourth series of ceramics were prepared following the same procedure as the HP specimen, except that the frequency was superimposed on the static pressure (40 MPa) while the temperature was kept at 900°C, 1100°C, 1300°C Oscillation pressure of ±5 MPa at 2 Hz. Finally, a fifth set of samples (labeled as HOP All, see Figure 1) were prepared by the same method, but the temperature at which both oscillatory pressure and static pressure were applied was kept at 900°C, 1100°C, 1300°C.
The density of the ceramics was evaluated by the Archimedes method in distilled water. The microstructure of the samples was characterized by scanning electron microscopy (SEM) on the S-4700 device. The hardness of the ceramics was evaluated using a Vickers hardness tester at 1.96N-15s. The breaking strength test was carried out on a sample of 3 mm × 4 mm × 36 mm by a three-point bending technique with a span of 30 mm and a test speed of 0.5 mm/min.
For more experimental data and reports, please pay attention and follow up the statistics of the data after the end of our experiment.
