Apparatus for treating workpieces of porous carbon material with liquid silicon to form silicon carbide, consisting of at least four chambers ( O1, O2, O3 and O4), which separately can be heated, cooled, evacuated and flushed with gases, and which are connected by sluices to each other, wherein in one embodiment with four chambers each have a chamber for the process steps c and f, and each has a chamber for the process steps a and b and d and e to be executed consecutively therein, wherein the steps are defined as a preheating of porous carbon workpieces under inert gas to the selected operating temperature T B 1 in the chamber O1 in the range of 1300°C to 1800°C, by introducing the workpieces into the first chamber O1, flushing the chamber after closing the sluice with an inert gas stream and heating from room temperature to the operating temperature T B 1, b lowering the pressure in the chamber O1 at the latest before opening the sluice 20 to the chamber O2 to the operating pressure of less than 10 hPa, c supplying liquid silicon to the porous carbon workpieces, which are received by a transport apparatus in the chamber 02 and placed on the pads 26 disposed in the siliconization apparatus, which are formed as porous wicks, at an operating pressure p B 2 in the chamber O2 of at most 1 Pa and an operating temperature T B 2 in the chamber O2 in the range of 1450°C to 1700°C, and saturating the porous carbon workpieces with liquid silicon, wherein the silicon reacts at least partially with the carbon present in the workpiece to silicon carbide under the formation of a siliconized workpiece, d lifting the siliconized workpieces from the wicks 26 and transporting the siliconized workpieces through the sluice 30 into the chamber O3, reaction of the liquid silicon in the workpieces at a temperature T B 3 in the chamber O3 in the range of 1500°C to 1900°C, wherein the operating temperature T B 3 in the chamber O3 is at least 50K higher than the operating temperature T B 2 under the formation of silicon carbide from carbon and silicon, e gassing of the workpiece in the chamber O3 by blowing cold inert gas and cooling from the operating temperature T B 3 to a conditioning temperature T k in the range of 500°C to 300°C, wherein the pressure rises from initially less than 1 hPa to normal pressure of 10 5 Pa, f transport of the workpieces 96 through the lock 40 in the chamber O4, and cooling the workpieces in position 97 to room temperature, first with inert gas and from temperatures of at most 300°C with air, and removal of the finished workpieces 98 through the sluice 50, wherein in which in the chamber O2 for the process step c a silicating apparatus is provided, which comprises a tank with liquid silicon and executed as porous wicks supports for the workpiece, and wherein the temperature T B 3 is at least 50 K higher than the temperature T B 2, and the workpiece in the chamber O3 for the process step d is no longer in contact with liquid silicon outside the workpiece. a preheating of porous carbon workpieces under inert gas to the selected operating temperature T B 1 in the chamber O1 in the range of 1300°C to 1800°C, by introducing the workpieces into the first chamber O1, flushing the chamber after closing the sluice with an inert gas stream and heating from room temperature to the operating temperature T B 1, b lowering the pressure in the chamber O1 at the latest before opening the sluice 20 to the chamber O2 to the operating pressure of less than 10 hPa, c supplying liquid silicon to the porous carbon workpieces, which are received by a transport apparatus in the chamber 02 and placed on the pads 26 disposed in the siliconization apparatus, which are formed as porous wicks, at an operating pressure p B 2 in the chamber O2 of at most 1 Pa and an operating temperature T B 2 in the chamber O2 in the range of 1450°C to 1700°C, and saturating the porous carbon workpieces with liquid silicon, wherein the silicon reacts at least partially with the carbon present in the workpiece to silicon carbide under the formation of a siliconized workpiece, d lifting the siliconized workpieces from the wicks 26 and transporting the siliconized workpieces through the sluice 30 into the chamber O3, reaction of the liquid silicon in the workpieces at a temperature T B 3 in the chamber O3 in the range of 1500°C to 1900°C, wherein the operating temperature T B 3 in the chamber O3 is at least 50K higher than the operating temperature T B 2 under the formation of silicon carbide from carbon and silicon, e gassing of the workpiece in the chamber O3 by blowing cold inert gas and cooling from the operating temperature T B 3 to a conditioning temperature T k in the range of 500°C to 300°C, wherein the pressure rises from initially less than 1 hPa to normal pressure of 10 5 Pa, f transport of the workpieces 96 through the lock 40 in the chamber O4, and cooling the workpieces in position 97 to room temperature, first with inert gas and from temperatures of at most 300°C with air, and removal of the finished workpieces 98 through the sluice 50,