Slip containing at least one aluminium oxide powder and at least one unstabilized zirconium dioxide powder, wherein a) the zirconium dioxide powder i) has a mean particle diameter of less than 300 nm, ii) shows only the monoclinic phase and the tetragonal phase in the X-ray diffraction pattern, with the proportion of tetragonal phase at room temperature being from 20 to 70%, and iii) is present in a proportion of from 2 to 20% by weight, based on the total amount of the slip, b) the aluminium oxide powder i) has a mean particle diameter of more than 300 nm and ii) is present in a proportion of from 80 to 98% by weight, based on the total amount of the slip, and c) the solids content, as the sum of aluminium oxide and zirconium dioxide, is from 50 to 85% by weight, based on the total amount of the slip.