BrazeLet^® Ni5R-9003

The nickel-based brazing alloy BrazeLet BNi5 has good wetting behaviour on stainless steels and nickel-based superalloys and is suitable for brazing in vacuum or protective atmospheres (hydrogen or argon). The high level of alloyed chromium results in a good hot gas and acid corrosion resistance. The high melting range of BrazeLet BNi5 makes it suitable for applications working at very high temperatures, for instance EGR coolers for trucks, automotive metal catalytic converters and turbine vanes. It is also a commonly used filler material for industrial heat exchangers. Joint properties can be further improved by employing a diffusion hold after brazing.

The brazing paste BrazeLet Ni5R-9003 can be used for roller coating fins or structured plates, typically found in flat heat exchanger designs. Depending on type of roller used the paste can be applied with thin layers either on top or on the side of the fin tips. Gap size between the paste roll and the scraper of 0.08 – 0.12 mm is recommended. The amount of paste is controlled by weight and is a function of the fins or structured plate design. BrazeLet Ni5R-9003 properties allow reliable application in a wide range of coating speeds, tested with good results from 3 m/min up to 20 m/min. The oil-based paste ensures reliable coating over time without drying on the roll. BrazeLet Ni5R-9003 has higher metal content and lower binder content compared to standard roller coating pastes, which decreases packaging and transportation needs for the same amount of brazing filler metal.

The coated fins can be dried with standard drying process (hot air) at 120 – 170 °C. The drying time depends on thermal mass, parts design and the used furnace and thus needs to be established. When dried, the paste has excellent adhesion to the metal sheet.