Surface Degradation of Additively Manufactured ABS for Naval Applications

Additive manufacturing (AM) has an essential role in the manufacturing process of several industries due to its rare shape-making ability that can optimize the creation of parts. Within the marine industry, the application of AM is confined due to the remaining questions regarding the degradation of polymers in a saline environment and whether AM is more viable than its traditional manufacturing (TM) counterpart. In this work, the surface degradation of AM and TM ABS samples is analyzed in a simulated marine environment. The simulated environment is created by having a set temperature of 27°C, 35°C, and 55°C respectively where the samples are aged for a duration of 7, 14, and 21 days. The ABS material is molded and cut into rectangle samples for comparison with its 3D printed counterpart. Upon observation, it was found that the surfaces of the AM samples degraded substantially more and at a faster rate in comparison to the TM samples. The AM samples also experienced a % weight change in the range of 2.5% compared to TM samples where the % weight change was below 1%. This research will help with the widespread adoption of AM ABS in the naval industry as well as provide information regarding the viability of AM material.

Hello, my name is Daniel Hernandez. I am a junior mechanical engineering student, here at GMU working with Dr. Ali Beheshti on the surface degradation of additively manufactured ABS for naval applications. This project is a continuation of my work done in the summer semester to determine the viability of additively manufactured ABS polymers in a saline environment in comparison to their traditionally manufactured counterpart. Additive manufacturing also known as 3D printing is the process of adding successive layers of material on top of each other vertically to create virtually any geometrical 3D structure at exceptional quality. A range of materials from metals to ceramics can be used in the additive manufacturing process, however, polymers such as ABS are an optimal choice given their exceptional mechanical properties and low costs. However, unlike most traditional materials, weathering factors have a substantial effect on polymers. In the maritime environment, polymers can degrade sustainably due to the corrosiveness of the ocean polymers. Thus, the usage of additively manufacture parts for naval applications is rather selective due to the change in resilience and degree of degradation that is imposed by the saline environment.

In terms of the experimental process of this project, samples were initially 3D modeled on CAD Inventor and were made using the lab printer. As for the traditionally manufactured samples identical samples were ordered from a plastic manufacturer. In order to simulate a saline environment aging chamber where setup for the ABS samples. The aging chambers consisted of tanks filled with artificial seawater heated to 27°C, 35°C, and 55°C accordingly using a water heater where these temperatures were selected in coordination to the room temperature and the proper temperatures needed to accelerate the aging of the samples. The set submerged durations of the samples were 7, 14, and 21 days where groups of additively and traditionally manufactured samples were placed in each tank. The water levels of the aging chambers where monitored every other day to ensure water heaters operated at set temperatures. The samples were then weighted every 3- 4-day intervals to record the percentage weight change. Where it was observed that the additively manufacturing samples saw a much greater % weight change in the range of 2.5% compared to their traditional counterpart where the % weight change was below 1%. This is due to the traditionally manufactured parts being much more rigid and compact in comparison to the additively manufactured parts which are susceptible to manufacturing defects. It was also seen that the rate of % weight change was more fluctuated in samples that were in the 35°C tank. Given that the heightened temperature increased the rate of hydrolysis that affects the degree of surface degradation. This was furthered observed in the 21-day aged samples where the surfaces of the additively manufactured samples show major deterioration along the top printing layers. Whereas for the TM samples the surface quality is rather intact though the top edges are showing signs of deterioration. It is important to note that the discoloring of these samples is not correlated to the aging process. This occurred due to the unexpected degradation of the wires used to keep the samples in place. The next steps of the project are to assess the surfaces of the samples through micro indentation and profiling tests. These tests will allow for the observation of the change in surface roughness, Young’s modulus, and hardness of the samples.
Thank you!