No abstract

The photoaging of coating based on toluene diisocyanate (TDI) and N75 was investigated though artificial light exposure. The properties of studied polyurethane coatings, such as film gloss loss and discoloration were examined at some aging interval. In addition, scanning electronic microscopy (SEM) and Fourier transform infra-red spectroscopy (FTIR) were used to measure the morphology and chemical change of coatings before and after exposed under UV light. It was found that the addition of N75 had a significant effect on the discoloration of polyurethane coating. Furthermore, SEM images showed that greater degradation occurred in the coating without N75. These findings were also supported by the results obtained from FTIR analysis and gloss loss. The above results suggested that a mixed curing agent system with a mass ratio of TDI to N75 between 5:5 and 3:7 be a possible substitute of pure N75 for weather resistance PU coatings.

To investigate the corrosion state of subsea pipeline under cathodic protection, the surface potential distribution of the pipeline has to be measured exactly, but it’s very difficult to measure directly in actually. On base of boundary element methods (BEM), a 2D model about pipe’s cathodic protection under sea water was established, and then software to calculate the electric field distribution on pipe surface in even media (seawater) was developed by way of Matlab. The developed software was verified through an experiment in lab. The result shows that numerical calculation based on BEM by Matlab is feasible for cathodic protection electric field of pipe in marine environment.

(Gd,La)2-x O2CO3:Eux3+(0.01 ≤x≤0.04) were synthesized via a flux method at 400°C, and their photoluminescence properties under vacuum ultraviolet (VUV) excitation were examined. The excitation spectra showed two bands in the region from 125 nm to 300 nm, the first band centered at 190 nm was ascribed to absorption of related CO32- complex, and the second broad band centered at 246nm and 278nm in Gd2O2CO3:Eu3+ was ascribed to the charge transfer band of O2-→ Eu3+. Series samples exhibited red emission at around 611 nm under vacuum ultraviolet excitation corresponding to the 5D0→ 7F2.transition of Eu3+.