Author Archives: Alex Shapiro

Dr. Alexander E. Shapiro has graduated from Moscow Aviation Technology University and received a Ph.D. degree in 1979 with emphasis on composite filler metals for brazing non-capillary joints of carbon steel tubes in conveyor belt furnaces under Endogas atmosphere. His area of expertise is the joining technology of titanium, magnesium alloys, carbon steel, stainless steel, ceramics, and C-C composites, in vacuum, hydrogen, or boron-fluoride atmosphere. Powdered and composite brazing filler metals created by Dr. Shapiro for joining aircraft parts have been used in the U.S. industry for many years. Alex is recognized also as an expert in sintering Ti-based composite materials and joining graphite or C/C composites by direct synthesis of high-temperature carbides or silicides in the joint. He published over 80 papers and patents. Also, he is a co-author of the AWS Brazing Handbook, 5th edition, published in 2007. Alex Shapiro is a member of AWS C3 Brazing & Soldering Committee and he is the columnist of “Brazing Q&A” in Welding Journal. Since 2007, he conducts Brazing Course WE7023 in Ohio State University for graduate students.

Brazing of titanium, ceramics, and graphite using new low-temperature Ti- and Zr-based amorphous foils

Applications of new brazing filler metals in the form of amorphous foils 50 microns thick, and 75 mm wide for vacuum brazing of titanium alloys, graphite, and ceramics are discussed in the paper. Brazed joints were evaluated by testing strength, microstructures, and sometimes phase compositions of base and filler metal interfaces. The following amorphous foils were tested: (a) TiBraze®200 (Ti-20Zr-20Cu-20Ni wt.%) with the melting range of 845-863°C (1553-1585°F), (b) TiBraze®590 (Zr-17Ti-20Ni-1Hf wt.%) with the melting range of 796-813°C (1465-1495°F), and (c) TiBraze®800 (Zr-14.7Ti-12.6Ni-7Cu-1Hf wt.%) with the melting range of 772-786°C (1422-1447°F).
Shear strength of brazed joints of CP titanium and Ti-6Al-4V alloy with copper, stainless steel 304, and Ni-plated carbon steel are reported, as well as microstructures of joints studied after brazing at different temperatures. Brazing temperatures of titanium joints with amorphous foils are significantly lower than that of standard filler metal AWS BTi-1 (Ticuni®). Brazing of titanium-to-ceramics and graphite with new foils should be done at temperatures greater by 50-60°C than that of brazing titanium-to-titanium. If compared to traditional active brazing filler metals which do not spread on ceramic surfaces, the tested Ti- and Zr-based amorphous foils revealed excellent wetting, and sometimes spreading, along ceramic surfaces of alumina and boron nitride, as well as graphite. Also, all samples of fin-plate titanium heat exchangers and honeycomb panels brazed with amorphous foils displayed good quality of the brazed joints.