Abstract: Ceramic material of high impact strength, in particular based on Si3N4 or ZrO2, having an HV10 hardness of not more than 15.5 GPa and an E modulus at room temperature of less than 330 GPa, wherein the material contains 0.2 to 5 wt. % of carbon particles which have a maximum particle size of 5 ?m, a process for the preparation of the ceramic material and the use thereof, in particular as roller bodies in bearings.

Abstract: Process and apparatus for a non-destructive continuous automatic quality control system monitoring a stoneware pipe and like objects, where the pipe is excited with a vibration generator up to a resonance frequency vibration, this vibration being measured with a vibration receiver, thereupon being registered and compared with values of a calibration curve. During the excitation and measuring, the pipe is borne on two turn crosses coated with rubber. The resonance frequency vibration is measured at the maximum of at least one antinode of vibration. The pipe is transported by a conveyor belt having rollers. A photoelectric pipe scanning system measures the nominal diameter of the pipe for preadjusting the position of the vibration receiver.