Author/Authors :
Hashemi Milani, Ali Akbar Faculty of Materials Engineering - Sahand University of Technology, Tabriz, Iran , Tavangar, Reza Faculty of Materials Engineering - Sahand University of Technology, Tabriz, Iran , Azadbeh, Maziyar Faculty of Materials Engineering - Sahand University of Technology, Tabriz, Iran , Kahinpoor, Ibrahim Iran Radiator Co., Tehran, Iran , Sadeghi- Nasab, Hossein Iran Radiator Co., Tehran, Iran
Abstract :
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
K2AlF5.H2O and KAlF4 with melting point around 580 °C was used. A
flux slurry was applied on the base metal, and dried at 220, 300 and 380
°C in air. Mechanical assessment revealed that when flux dried at 300 °C,
the joint withstands maximum shear stress of 44 MPa with complete
bonding. At 220 °C and 380 °C, joint shear stresses are 34 MPa, 30
MPa respectively. 380 °C dry-off temperature under nitrogen gas
improved shear strength to 39 MPa. Taking dry-off temperature as 300 °C
the amount of defective heat exchangers was reduced from 6% to 2% on a
daily basis.
