US 2012/0057983 A1Published application

Method for forming surface layer, method for forming erosion resistant component and steam turbine blade

AssigneeMitsubishi Electric Corporation

InventorsAkihiro Goto, Hiroyuki Teramoto, Nobuyuki Sumi, Yoshikazu Nakano

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Abstract

A method for forming a surface layer, the method including: arranging a member in a machining fluid; and forming a surface layer including silicon by supplying silicon component from the silicon electrode to the member side by applying a predetermined voltage and generating electric discharge, wherein a value of an electric discharge detection level is set to be equal to or larger than a value obtained by adding a voltage depression at the silicon electrode to an arc potential during electric discharge, and wherein the surface layer is formed on a surface of the member by repetitively performing, after the voltage is applied, detecting the electric discharge generated between the silicon electrode and the member by detecting a drop of the voltage to be lower than the electric discharge detection level, stopping applying the voltage for a predetermined time, and applying the voltage again after a predetermined break time.

Claims11

Dependent claims

A method for forming a surface layer, the method comprising:

arranging a member in a machining fluid;
and
forming a surface layer including silicon by spacing an silicon electrode from the member by a predetermined distance, and by supplying silicon component from the silicon electrode to the member side by applying a predetermined voltage between the member and the silicon electrode and generating electric discharge,
wherein a value of an electric discharge detection level, which is for recognizing that the electric discharge is generated when the applied voltage becomes lower than the value, is set to be equal to or larger than a value obtained by adding a voltage depression at the silicon electrode to an arc potential during electric discharge, and
wherein the surface layer including silicon is formed on a surface of the member by repetitively performing, after the voltage is applied, detecting the electric discharge generated between the silicon electrode and the member by detecting a drop of the voltage to be lower than the electric discharge detection level, stopping applying the voltage for a predetermined time after the electric discharge is generated, and applying the voltage again after a predetermined break time.

2 more elements

A method for forming an erosion resistant component, the method comprising:

spacing an silicon electrode, which is formed in a shape of a portion of the erosion resistant component to be treated, from the portion of the erosion resistant component to be treated, which is arranged in a machining fluid, by a predetermined distance;
and
forming a surface layer including silicon on a surface of the erosion resistant component through an electric discharge surface treatment, by repetitively performing, applying a predetermined voltage between the erosion resistant component and the silicon electrode, detecting the electric discharge generated between the silicon electrode and the member by detecting a drop of the voltage to be lower than an electric discharge detection level which is equal to or larger than a value obtained by adding a voltage depression at the silicon electrode to an arc potential while the applied voltage is electrically discharged, continuing the electric discharge for a predetermined time and stopping voltage application for a break time after the continuance of the electric discharge.

Dependencies are inferred from the claim text.