Preparation and Characterization of Metatitanic Acid/Urea‐Formaldehyde Microcapsules as Wear‐Reducing Additives

Abstract

Metatitanic acid/urea‐formaldehyde microcapsules were synthesized to inhibit the erosion of gun barrel resulting from the propellant combustion. The microcapsules were prepared by one‐step in‐situ polymerization method. SEM and EDS were employed to characterize the morphology, core‐shell structure and the chemical composition of the microcapsules. FTIR spectra and XRD patterns confirmed the formation of crystalline urea‐formaldehyde resin on the surface of the metatitanic acid particle. TG results showed that the thermal decomposition residue weight ratio of the microcapsules in air was 12.8 %. Kinetic parameters of thermal decomposition of propellant with and without the microcapsules were calculated based on the DSC results, respectively, which proved the good compatibility between the microcapsules and the double‐base propellant. Erosion tube comparative test showed the wear‐reducing efficiency reached 18.54 % with 1.5 wt.% addition of microcapsules. The combination of metatitanic acid and urea‐formaldehyde resin surprisingly resulted in a synergistic effect, which was attributed to the better dispersibility of TiO2 particles generated by metatitanic acid microcapsules. The metatitanic acid/urea‐formaldehyde microcapsules exhibit a potential application for propellant erosion additive.

Influence of Various Flame Temperatures of the Gun Propellant on the Effectiveness of the Erosion Inhibitor and Relevant Mechanisms

“…Up to now, the incorporation of wear-reducing additives into propellant charges has emerged as an efficient and low-cost technique, extensively employed in a diverse range of firearm systems over recent decades. ,− The inhibitors usually involve inorganic materials with a low thermal conductivity like talc, TiO 2 CaCO 3 , and BN, and organic materials like paraffin and silicone. ,,, These inhibitor materials can be directly incorporated into the gun propellant matrix ,, or added to the propellant charge placed between the projectile and propellant grains. ,, These inhibitors include not only single material like silicone oil, talc, TiO 2 , K 2 SO 4 , and BN ,, but also the mixing of inorganic and organic inhibitor materials like titanium dioxide (TiO 2 )/paraffin, talc/paraffin, and microcapsules. − In this perspective, recent research efforts have been dedicated to the synthesis and optimization of composition for inhibitors. ,, Some types of inhibitors show significant erosion-reducing effects for general propellants, including single-, double-, triple-, and RDX-based gun propellants. However, conventional inhibitor materials also face challenges in achieving the desired erosion-reducing effect for propellants with higher energy due to the continuously increasing demand for modern high chamber pressure guns.…”

“…13−15 In this perspective, recent research efforts have been dedicated to the synthesis and optimization of composition for inhibitors. 14,15,21 Some types of inhibitors show significant erosionreducing effects for general propellants, including single-, double-, triple-, and RDX-based gun propellants. However, conventional inhibitor materials also face challenges in achieving the desired erosion-reducing effect for propellants with higher energy due to the continuously increasing demand for modern high chamber pressure guns.…”

“…These high energy propellants exhibit an enhanced flame temperature and severe erosion. The synthetic methodologies of inhibitors have been extensively studied in prior reports − which have also demonstrated their remarkable effectiveness in reducing erosion for a specific propellant formulation. However, the influence of flame temperatures on the inhibitor efficiency has rarely been extensively discussed in relation to various propellant composites.…”

Study on the adhesive mechanism of erosion reducing additive on the bore surface of gun barrel

“…It can not only reduce the erosion and wear, but also easy to load. For these reasons, researchers are constantly working on ERAs, and research achievements include BNH x [1], BN [2], fullerene-like WS 2 particles [3], hollow TiO 2 /polyimide particles [4], Si 3 N 4 /polymethyl methacrylate/para n composite phase change materials [5], TiO 2 /BN/polymethyl methacrylate/para n composite phase change materials [6], Si 3 N 4 /TiO 2 /polystyrene composite microcapsules [7,8], zeolitic imidazolate framework/para n composite phase change materials [9] and metatitanic acid/ureaformaldehyde microcapsules [10].…”