Corrosion Testing

Corrosion of copper in de-ionized water (DIW) systems is of particular interest to maximizing the lifetime of copper heat exchangers.  To fundamentally understand the corrosion process and identify methods to reduce the corrosion rate of copper in DIW systems, Advanced Cooling Technologies, Inc. (ACT) utilizes electrochemical techniques to evaluate the effectiveness of various passivation techniques, such as ACT’s ANCERTM coating.  ACT uses a  VersaSTAT V3-300 potentiostat from Princeton Applied Research (shown below) equipped with a frequency response analyzer (FRA) giving it electrochemical impedance spectroscopy (EIS) capabilities, which is ideal for passivation coating development.  EIS is a fast, accurate, non-destructive characterization method of corrosion phenomena that is conducted by imposing a low-amplitude, alternating voltage onto a sample (working electrode) immersed in an electrolyte solution and measuring the phase shift of the responding current signal at varying frequencies.  This instrument also gives ACT the ability to conduct linear polarization resistance (LPR) and Tafel Analysis measurements of corrosion current and rate as well as cyclic polarization for measurements of localized corrosion phenomena.

 

Figure 7.  Princeton Applied Research VersaSTAT V3-300 potentiostat used for evaluating corrosion behavior in simulated operating conditions.

Figure 1. Princeton Applied Research VersaSTAT V3-300 potentiostat used for evaluating corrosion behavior in simulated operating conditions.

For evaluating the corrosion rate of samples in pumped, single phase coolant systems, such as DIW, ACT designs and fabricates custom flow cells with integrated electrochemical cells (shown below in Figure 2).  These systems are fully integrated with pumps, flow controls, pH, electrical resistivity, and dissolved oxygen control.

Figure 8.  DIW corrosion testing facility at ACT.  A pumped loop DIW system was fabricated to evaluate the corrosion rate of copper in simulated operating conditions.

Figure 2. DIW corrosion testing facility at ACT. A pumped loop DIW system was fabricated to evaluate the corrosion rate of copper in simulated operating conditions.

The DIW corrosion testing facility at ACT was developed to accurately simulate the coolant conditions in copper microchannel coolers used for laser diode thermal management.  Copper samples were placed within the flow cells, which also serve as electrochemical cells for evaluating corrosion rate, and exposed to high velocity, high purity DIW, and thereby simulating operating conditions.  During the evaluation of copper, the pH of the coolant was reduced to 6 in order to accelerate the corrosion rate of the copper.  Throughout the duration of the exposure, the corrosion rate of ANCERTM coated and equivalent uncoated baseline samples are evaluated to determine the reliability of the coating under intended operating environments.

If you have corrosion problems that need to be investigated, please contact ACT today.