Physical Removal of Ablated Aluminum with Titanium Scraper
Gyorfi, Tibor John
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A railgun is a high velocity launcher which relies on the Lorenz force to accelerate projectiles commonly made of aluminum. When a railgun is fired, the large current required to accelerate the projectile to high speeds causes a portion of the armature’s contacting surface to ablate onto copper rails with the largest concentration located at the startup region. This ablation impedes the path of fired armatures causing deformation of subsequent armatures. In addition, aluminum buildup can hasten the rate of rail wear by increasing the incidence of voltage spikes due to poor continuity as well as high velocity shearing of the copper substrate. The goal of this project was to design a scraper which could remove the ablated aluminum without damaging the soft copper rail surface and increase the useful life of a set of railgun rails, decreasing the number of costly and time-consuming teardowns. Since previous research did not exist on the topic, numerous materials were investigated for use as a high velocity scraper, however it was found that titanium Ti-6AL-4V had the best combination of conductivity, stiffness, strength, light weight, and fracture toughness to handle the immense forces within the railgun. A plow shaped tip was designed to attach to existing armature types. The combination was then tested on a set of rails with massive aluminum ablation and was shown to be a success after the rail returned to a favorable condition and excessive deposits were removed. After launching approximately 100 standard shots through the test gun, the scraper was fired, and results were observed to be acceptable. Future work will include improvements in armature manufacturability by utilizing selective laser sintering 3d printing technology.