Effect of NOCOLOK® Flux Dry-off Temperature on Mechanical Properties of Brazed Joint of Automotive Aluminum-Based Heat Exchangers

Drying temperature of the flux at normal atmosphere has a crucial role in brazing quality in automotive aluminum-based heat exchangers. Over the course of this research, NOCOLOK® flux consists of two phases of K۲AlF۵.H۲O and KAlF۴ with melting point around ۵۸۰ °C was used. A flux slurry was applied on the base metal, and dried at ۲۲۰, ۳۰۰ and ۳۸۰ °C in air. Mechanical assessment revealed that when flux dried at ۳۰۰ °C, the joint withstands maximum shear stress of ۴۴ MPa with complete bonding. At ۲۲۰ °C and ۳۸۰ °C, joint shear stresses are ۳۴ MPa, ۳۰ MPa respectively. ۳۸۰ °C dry-off temperature under nitrogen gas improved shear strength to ۳۹ MPa. Taking dry-off temperature as ۳۰۰ °C the amount of defective heat exchangers was reduced from ۶% to ۲% on a daily basis.

کلیدواژه ها:

Brazing of Aluminum ، NOCOLOK® Flux ، Aluminum-Silicon