Investigation of Sintering Processes by Tomography
Sintering especially of loose particle packings is accompanied by dimensional changes of the specimen. The growth of inter particle contacts under the influence of the Laplace pressure is well understood and described by the two particle model. On the other hand the understanding of other fundamental sintering phenomena i.e. cooperative material transport processes is rather vague. To overcome this limitation for near net-shape production of components by powder metallurgy an improved model of particle rearrangement processes is required. First efforts to obtain necessary experimental data were performed at 1D and 2D models. But recent improvements of high resolution synchrotron computer tomography (SCT) setups allow the acquisition of in-situ data of particle rearrangements. In-situ studies of particle rotations during sintering were conducted at the ESRF in Grenoble. The rotations during free sintering of monocrystalline particles were investigated during continuous heating up to 1050 °C or with frequent interruptions of the heating by 1 hr dwell times every 100 °C. In contrast to 1D specimens measured by Wieters the 3D specimens showed negligible rotations. This must be attributed to the constraints in 3D samples. To obtain a more detailed insight in the rotations the particles of one sample were marked. It is possible to show that the particles perform intrinsic rotations. Therefore a new rotation model is developed. The intrinsic rotations are confirmed by complementary EBSD analyses as well.
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
B. Kieback et al., "Investigation of Sintering Processes by Tomography", Materials Science Forum, Vols. 638-642, pp. 2511-2516, 2010