THERMOCHEMICAL TREATMENT APPARATUS Russian patent published in 1995 - IPC

FIELD: strengthening of metal cutting tool. SUBSTANCE: thermochemical treatment apparatus has vacuumizer 1, where cathode 2, anode 3, optically nontransparent screen 4, electrically insulated holder 5 formed as wall with holes 6 for receiving articles to be treated are positioned. Power is supplied to electrodes 2 and 3 from power source 8, which has circuit with current relay 9 having open contact 11. When holder 5 is positioned between anode 3 and screen 4, charge is passed through article cavities to form homogeneous plasma inside them. To provide heating of inner surfaces, negative potential of up to 400 V is supplied from source 10. Gaseous plasma ions are accelerated in layer positioned adjacent to cavity surface to bombard its surface. As a result cavity surface is heated and subject to nitriding. EFFECT: increased quality of treatment by presence of homogeneous plasma within hollow articles and uniform thickness of layer subject to nitriding. 3 dwg