Method of coating internal surfaces of an object by plasma spraying

A method of coating the internal surface of a tube by plasma spraying by means of a plasma spray torch which has a torch arm, said method comprising pushing a tube of an inside diameter of less than 30 mm onto the torch arm;

• igniting the plasma spray torch, and during the plasma spray operation turning the tube and moving it axially relative to the torch arm so as to form a layer having a thickness of between 0.01 and 0.5 mm over the internal surface of the tube further comprising using a spray material on the basis of a Ni Mo alloy with additions of up to 30% Fe and up to 5% B.

A method of coating the internal surface of a tube by plasma spraying by means of a plasma spray torch which has a torch arm, said method comprising pushing a tube of an inside diameter of less than 30 mm onto the torch arm;

• igniting the plasma spray torch, and during the plasma spray operation turning the tube and moving it axially relative to the torch arm so as to form a layer having a thickness of between 0.01 and 0.5 mm over the internal surface of the tube further comprising using a Ni-Cr-base alloy powder with 15% Cr and additions of up to 20% of an element selected from the group consisting of Mo, Fe, B, Si and mixtures thereof as the spray material.

A method of coating the internal surface of a tube by plasma spraying by means of a plasma spray torch which has a torch arm, said method comprising pushing a tube of an inside diameter of less than 30 mm onto the torch arm;

• igniting the plasma spray torch, and during the plasma spray operation turning the tube and moving it axially relative to the torch arm so as to form a layer having a thickness of between 0.01 and 0.5 mm over the internal surface of the tube further comprising using an Fe-Mo-base alloy powder with 10% Mo and additions of 5% Ni and up to 5% of the usual elements present in steel alloys such as Mn, Si and C, as the spray material.

A method of coating the internal surface of a tube by plasma spraying by means of a plasma spray torch which has a torch arm, said method comprising pushing a tube of an inside diameter of less than 30 mm onto the torch arm;

• igniting the plasma spray torch, and during the plasma spray operation turning the tube and moving it axially relative to the torch arm so as to form a layer having a thickness of between 0.01 and 0.5 mm over the internal surface of the tube further comprising using a Cr-base alloy powder with additions of up to 10% C, up to 30% Fe and up to 30% Mo as the spray material.