An eccentric screw pump with a rotor (2) and with a rotationally fixed stator (6; 6′) surrounding the rotor (2). The rotationally fixed stator includes at least one elastomeric portion, wherein a pressure chamber (16) is arranged on this elastomeric portion of the stator (6; 6′) at a side facing away from the rotor (2). The pressure chamber (16) is connected to a pressure region of the eccentric screw pump such that the at least one elastomeric portion of the stator (6; 6′) is subjected to a pressure produced by the eccentric screw pump.

A dry vacuum pump has a stator (2) and two rotors (5) that are accommodated in at least one compression chamber (3) of the stator (2), the rotors (5) being configured to rotate synchronously in opposite directions so as to drive a gas to be pumped between an intake and a delivery of the vacuum pump. The rotors (5) and the compression chamber (3) of the stator (2) are coated with a nickel-phosphorus coating (11) comprising between 9% and 14% phosphorus and having a thickness greater than 20 μm, the nickel-phosphorus coating (11) having undergone a hardening heat treatment comprising a step of heating to a treatment temperature greater than 250° C. for a treatment duration greater than one hour, so as to have a hardness greater than 700 HV.