Takio Okuda

Study on vapor-shielded pressure bonding process of nonferrous metals by resistance heating and its inprocess quality control. (Report-6). Improvement of properties of contact-bars by applying new bonding process.

The bonds in mass-produced electric devices are recently required high reliability in precision and in quality.For the purposes, new bonding process for dissimilar metals by resistance heating is successfully developed.To control the material deformation, the optimum electrode constitution of materials, sizes and their arrangement is established as described in Report-1 and Report-2.To get high quality at bonds, the vapor shield process available to clean the material interface while bonding is developed as described in Report-3 and Report-4.Moreover, inprocess control system for getting high quality bonds stably is newly developed and automatic bonder for mass-production line of contact-bars is successfully manufactured as described in Report-5.In this study, main properties of contact-bars bonded by the new process which is operated in massproduction line are examined in comparison with the conventional one by brazing.The main results obtained are as follows;1) Bond strength increases of 40% as compared with the conventional one.2) Temperature rise at bond by arcing heat input to the contact-top is sharply suppressed.3) Bond strength at high temperature of 973 K is three times as high as the conventional one.4) Hardness of carrier bar required spring property is kept at higher value.5) Noticeable longer life of electromagnetic switchgears is confirmed by JEM-standard test.

Study on vapor shielded pressure bonding process of nonferrous metals by resistance heating and its inprocess quality control. (Report 4). Shielding mechanism by vapor and constitution of vapor shielded pressure bonding process.

Contact-bars of electromagnetic switchgears are required high precision and high quality at bonds. For the purposes, the Vapor Shielded Pressure Bonding (V.S.P.B) process and its inprocess control system are successfully developed.To control the material deformation, thermo-characteristics by resistance heating while bonding are examined, and the optimum electrode materials and their constitution are selected as described in the report-1 and -2Then, the examination of bonding quality and its improvement by vapor shield process are described in the report-3.In this study, the mechanism of vapor shielding on cleaning action at the bonding interface and the fundamental properties of bonds are investigated.Moreover, the basic constitution of Vapor Shielded Pressure Bonding Process are examined and the each optimum condition is clarified.The main results obtained are as follows;1) The follow facts about surface oxidation of materials are clarified by AES.a) Material heating in air atmosphere accelerates the striking oxidation.b) Vapor shield can effectively control the oxidation while heating.2) The essential factors of vapor shield process and the typical features of bonds are clarified.a) Liquid composed by 15%-ethanol solution in water is good for vapor shield.b) Compounds both at bonds and expelled metal obtained under vapor shield are of eutectic of Ag and Cu.c) Vapor shield can raise the bond strength of 28% comparing with the one in air atmosphere.3) V.S.P.B process for high precision and high quality of bonds consists of the suitable vapor shielding condition and the optimum resistance heating conditions