The Development Of A Virtual Instrument Testing System Based On PXI Module And Its Application In Corrosion Research

Since it came forth in 1980’s,virtual instrumentation has been widely used in the field of automatic test and electronic measurement technology owing to its cost-effectiveness,flexibility and short development cycle. In the area of corrosion electrochemical,the Virtual instrument technology can be used to improve the maneuverability and flexibility of the testing instruments and by means of the ready-made hardware module and software platform rapidly build measurement systems, saving cost and reducing the investments in scientific research equipment.In the paper, the virtual corrosion electrochemical testing system was developed, based on the PXI module, LabVIEW software development platform and electrochemical workstation of NI. The test system could nearly automatically and synchronously test multi-channel wire beam electrode(WBE) galvanic current and galvanic voltage, and polarization curve as well, then collecting data through data acquisition card, which were displayed on the PC and were stored automatically by means of the LabVIEW software program design. The test system had the advantages of high testing speed, high accuracy, good current and voltage synchronization, and easily coupled with other electrochemical measurement techniques etc. A number of laboratory simulation tests were carried out by applying the system and the wire beam electrode technique to the corrosion electrochemical test, the expected results have been achieved.In different marine environments, the Virtual testing system was used to test the galvanic current, galvanic voltage and polarization curve of two different materials, three kinds of different size wire beam electrode(Q235 carbon steel wire beam electrode(8×8,10×10), HPB300 hot rolled round bar in concrete(2×18) wire beam electrode). The experimental results showed that: Q235(8×8) showed typical Evans ring phenomenon in the situation of seawater droplets corrosion. The central region of the droplet was the anode region, and the surrounded liquid droplet was the cathode region, which occurred galvanic corrosion mainly resulting from forming oxygen concentration gradient. Q235(10×10) corrosion from seawater and sea mud interface was determined by the dissolved oxygen concentration, mud impedance and potential difference factors, etc. Sea mud was the anode region and seawater was the cathode region. The corrosion of HPB300 Hot rolled round bar electrode array(2 x 18) was determined by oxygen diffusion and salt penetration in the simulated marine environment.Conclusions drawn from the above experiments were consistent with the mechanism of the corrosion behavior mentioned in the literature, indicating that the test performance of the measurement system was stable, the data obtained were reliable, which showed that the test system could be well used in electrochemical corrosion test.