Preparation and properties of an organosilicon-modified coating to protect combustible cartridge cases

Abstract

To improve the environmental adaptability and mechanical properties of combustible cartridge cases (CCCs), a novel organosilicon-modified coating was proposed to increase heat resistance, water resistance, salt resistance, and mechanical properties. Herein, four organosilicon-modified coatings were prepared using the sol-gel method with an alkaline silica sol, methyltrimethoxysilane, and diphenyldimethoxysilane. Fourier-transform infrared spectroscopy confirmed the synthesis of the organosilicon resins, which possessed cross-linked semi-inorganic polymers with Si-O-Si main chains and various grafted organic functional groups. The optimal sample retained its heat resistance at 230 ℃ for 168.4 s, which was significantly longer than the previous resin-centric composite layer result of 108.8 s. Moreover, after the sample was immersed in water for 120 h, it only absorbed 1.98 wt% water, and 5.78 wt% saltwater after 3 days, and the water contact angle (WCA) reached 101º. Furthermore, the elongation-at-break reached 29.22%, which was significantly higher than the 3.69% of the CCC control sample. Therefore, the organosilicon-modified coating may protect CCCs during industrial fabrication processes, which can significantly improve the overall performance of CCCs.