Pore-free sintered bodies on the basis of silicon carbide which are suitable as substrates for hard disks, and methods for the fabrication thereof

摘要

Dense sintered bodies are provided which a) comprise from 45 to 99.5 wt % of SiC, the SiC being present in the sintered body as a crystalline first phase, and b) comprise from 0.5 to 55 wt % of a sintering aid, from 0.5 to 30 wt % of which is selected from the group consisting of reaction products of Al2O3 with Y2O3, mixtures of at least one nitrogen-containing aluminum compound with reaction products of Al2O3 with Y2O3, mixtures of at least one rare earth oxide with at least one nitrogen-containing aluminum compound and/or Al2O3, and from 0 to 25 wt % of which is selected from the group of the nitridic silicon compounds, the sintering aid being present in the sintered body as a second phase and optionally further phases, wherein the second phase and optionally the further phases are either amorphous to an extent of more than 10% or are present in amorphous form at the interface to the first phase to a width of at least >/=5 ANGSTROM , and the polished surface of the sintered body does not contain any pores having a diameter >1 mu m.