K. Matsu, Tokyo Braze Co., Ltd., Tokyo, Japan; Y. Miyazawa, T. Ariga, Tokai University, Kanagawa-ken, Japan
The paper reviews the investigation of titanium brazing for manufacturing titanium heat exchangers. Being considered for corrosion resistance applications of titanium heat exchangers and availability on commercial scale of the filler metal, powder form of titanium based filler metals were carefully investigated. Brazing was done in vacuum furnace with slow heating rate and long brazing time being considered reliability of assembly on commercial base.
Brazing filler metals were studied by Differential Thermal Analysis to determine melting range. Characteristics of brazing filler metals were evaluated by wet test, gap flow test. Mechanical property of the brazed joints was estimated by shear strength test. Interfacial reactions were observed by optical microscope, SEM and EPMA.
This paper reviews the investigation of titanium brazing for manufacturing titanium heat exchangers. Joint strength was examined by shear strength test. Reliability of joint strength was evaluated by calculation of Weibull slope. Different formation of microstructure was effected Weibull slope, which was also related to reliability of joint strength. Microstructure of brazed joints was observed by optical microscope, SEM and EPMA. It is understood that sufficient brazing time is necessary to improve mechanical properties of titanium heat exchangers.
