Method and apparatus for thermochemical treatment
AssigneeThe Electricity Council
InventorsAmos C. Dexter, Michael I. Lees, Barry J. Taylor
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Abstract
Known techniques of plasma case hardening of workpieces may fail to provide sufficient treatment to re-entrant portions, such as fine holes, in the workpiece. This specification discloses a technique of pulsed plasma treatment in which the duration of the plasma pulses and the intervals between them are selected to allow a substantially even distribution of the gas which forms the plasma over all the surface to be treated of the workpiece.
Claims8
A method of thermochemical treatment of a workpiece having first surface portions less accessible for treatment than other portions in a gas comprising the steps of bombarding a workpiece with ions for a series of time periods to provide a desired surface treatment to the workpiece, separating the steps of active bombardment by an interval of substantially no active ionic bombardment, the duration of the steps and the intervals between them being timed to provide a substantially even distribution of the gas over all the surface portions to be treated of the workpiece.
An apparatus for thermochemical treatment of a workpiece comprising means for heating the workpiece to a predetermined temperature;
- means providing a gas about the workpiece;
- and means operable to induce repeated time separated periods of ionic bombardment to provide a desired surface treatment and said means to induce including means to provide intervals of substantially no ionic bombardment between the periods of ionic bombardment to allow, during the treatment, a substantially even distribution of the gas over all the surface to be treated of the workpiece.
Dependencies are inferred from the claim text.