Abstract No.:
6628

 Scheduled at:
Tuesday, May 04, 2021, Hall 1 12:00 PM
Applications


 Title:
Assessment of interactions between post-braze Nocolok flux and engine coolant in the field and means to reproduce in the laboratory

 Authors:
Mary Ranger* / CCI Manufacturing Illinois Corporation, United States
Yoshi Sato / CCI, Japan
Fred Alverson/ CCI, IL

 Abstract:
Automotive cooling systems contain an increasing number of water-cooled aluminum heat exchangers including radiators, heater cores, charge air coolers, oil coolers, transmission coolers, battery pack coolers, and electronic cooling devices. These modern heat exchangers contain many internal braze joints and narrow fluid passageways to improve heat transfer efficiency. Most aluminum heat exchangers are control atmosphere brazed using NocolokĀ© flux. The post-braze flux in these heat exchangers is exposed to engine coolant. Interactions between the post-braze flux and engine coolant can impact engine coolant additive package / inhibitor stability, impact the corrosion protection performance and / or cause deposit formation.
This paper will present an overview of coolant-flux interactions experienced in the field from dye change to heat exchanger plugging and corrosion. This paper will then review several different laboratory tests used to assess coolant-flux interactions. The test methods will be presented in detail including the test set-up, the factors involved, the pros and cons and a review of results. One method that enables a comparison of results from various coolants will be reviewed in the detail. In this method, a variable amount of post-braze flux is added to the coolant followed by quantitative analysis of the coolant-flux reaction products, an evaluation of the impact on coolant additive stability and an evaluation of coolant aluminum corrosion protection. Results will be presented with several different types of coolants including OAT only, hybrid silicate OAT coolants, and phosphate OAT coolants, all tested with varying levels of flux. It will be demonstrated that some coolants have threshold levels of flux at which reactions between the flux and coolant become more apparent and/or adverse.


<= go back