Fluid-induced metal corrosion failure is one of the main causes of pipe wall damage. In this paper, aimed at the corrosion failure of stainless-steel pipe wall in high-speed flowing liquid, a self-made micro three-electrode electrochemical test system was used to test the electrochemical characteristics of the pipe under different flow rates and different Cl− concentrations. In the experiment, the changes of open circuit potential, polarization curve and impedance spectrum of 304L stainless steel surface were obtained. At the same time, the corrosion rate of the material under different conditions was obtained by fitting. The results show that the corrosion rate varied non-linearly with increasing flow velocities. In addition, with the increase of Cl− concentration, the corrosion rate increased at a slower rate. The material surface under high concentration and high flow rate conditions was subject to physical cutting and electrochemical reactions, showing an activated and easy pitting corrosion state. The results of this study can provide data for failure analysis and life extension of pipelines and equipment in service.
22 January 2021 in Journal of Materials Engineering and Performance
ZrW2O8-Cf/E51 composite with a negative Coefficient of Thermal Expansion (CTE) was fabricated by a method combining mechanical stirring with ultrasonic vibration, then microstructures and properties of the composites were analyzed and summarized by scanning electron microscope (SEM), DIL 402 C thermal expansion tester and electronic universal testing machine. The results showed that particles distribution defects and impregnation defects of carbon fibers would occur when the process parameters were not controlled properly. Long curing time and good fluidity of resin were beneficial for resin impregnating carbon fibers and bubbles overflow. However, for the ZrW2O8-Cf/E51 composites studied in this paper, long curing time and low viscosity could cause particle settling and accumulation. The experimental results confirmed that the CTE (about −0.52 × 10−6/°C) and tensile strength (about 440 MPa) of E51 resin were improved with the addition of carbon fibers and ZrW2O8 particles.