An on-line corrosion rate measurement system was developed using a personal computer, a data acquisition board and program, and a 2-electrode corrosion probe. Reliability of the developed system was confirmed with through comparison test. With this system, the effect of sodium nitrite (NaNO 2 ) as a corrosion inhibitor were studied on iron and aluminum brass that were immersed in sodium chloride (NaCl) solution. Corrosion rate was measured based on the linear polarization resistance method. The corrosion rates of aluminum brass and iron in 1% NaCl solutions were measured to be 0.290 mm per year (mmpy) and 0.2134 mmpy, respectively. With the addition of 200 ppm of NO 2 -, the corrosion rates decreased to 0.0470 mmpy and 0.0254 mmpy. The addition of NO 2 -caused a decrease in corrosion rates of both aluminum brass and iron, yet the NO 2 -acted as a more effective corrosion inhibitor for iron. than aluminum brass.
Carbon materials are widely used as anode on Li-ion battery (LIB). In particular, the effect of electrical conductivity (EC) on the anode is related to capacity and retention, which are important factors for LIB performance. However, the relationship between carbon properties and battery performance is still unclear. This uncertainty is due to the sp3 and sp2 bond states, the diversity of carbon like amorphous structures, and impurities.
In this study, we investigate the structure-EC relationship from over 50 carbon samples. The carbon used was graphite, carbon nanotube (CNT), carbon black (CB), hetero atom doped carbon, and the ones synthesized by solution plasma. The carbon materials are evaluated by X-ray diffraction (XRD), Raman spectroscopy, Thermogravimetric analysis (TGA), Energy-dispersive X-ray spectroscopy (EDX), and four-point probe (FPP) measurement. The characterized values were extracted from the results and analyzed by Cluster analysis (CA) with JMP software. CA was used to classify how carbons are related to each other.
The clusters were divided into 3 big groups according to the presence of 002 peak and the degree of defects. Some clusters have been shown high conductivity when they have high crystallinity. It was also found that the heteroatomic effect was higher than the crystallinity in the part showing low EC range. However overall correlation with EC is still unclear. This is because XRD and Raman can only provide information of symmetric or periodic structures rather than the effect of disorder or amorphous parts, sizes and shapes are not considered. Thus, analysis of shapes and sizes such as SEM and BET, and additional measurements related to amorphous structures may be helpful to clarifying the correlation.
Figure 1
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