Plate-like ceramic molded body used as substrate plate in the manufacture of magnetic reading-writing heads is made from liquid phase sintered silicon carbide

摘要

Plate-like ceramic molded body has a surface A lying between 15 and 1000 cm2, a thickness d of 0.2-5 mm and is made from liquid phase sintered silicon carbide. The molded body has a planarity of less than 0.05 x 10-3 of its characteristic dimension, a front side having a roughness Ra less than 3, a density of more than 99% of its theoretical density, especially more than 99.9% of its theoretical density, pores of a maximum size less than 10, especially 2 microns m, a ferromagnetic amount of its magnetization in an external field of less than 10-2, preferably more than 10-3 e.m.u/cm3, a specific electrical resistance rho more than 103 OMICRON cm measured at a measuring voltage of 1 V, a heat conductivity of more than 70 W/mK, a fracture toughness of more than 3.5 Mpam1/2, an edge toughness of less than 300 N/mm, a four-point bending strength of more than 400 MPa, a Vickers hardness of more than 20 GPa, and an elastic modulus of more than 380 GPa. An Independent claim is also included for a process for the production of a molded body. Preferred Features: The molded body contains SiC crystals consisting of a SiC core and SiC mixed crystals surrounding the core or only SiC mixed crystals, and a binder phase having a crystalline portion and an amorphous portion. The SiC mixed crystals also contain Al, O and/or N.