Presenter: Grant Ogilvie
Authors: Grant Ogilvie, Brian Jensen, Anton Bowden
Faculty Advisor: Brian Jensen
Institution: Brigham Young University
Carbon infiltrated carbon nanotube (CICNT) coatings for metals have strong potential for use in medical implants because they are conducive to bone cell growth while inhibiting microbial growth. However, growing carbon nanotubes on stainless steel (SS) has been shown to make it subject to corrosion. The goal of this research was to improve the corrosion resistance of CICNT-coated SS by adding a thin film of chromium before CICNT growth. A thermal evaporator was used to coat squares of SS (321 and 316) with 10nm, 20nm, and 50nm of chromium. The samples were then subjected to the following CICNT direct growth furnace procedure: 2 min in air at 800°C, 10 min in ethylene and argon at 800°C, and 5 min in ethylene and argon at 900°C. Using a scanning electron microscope it was found that only the 10nm layer of chromium on 321 SS created a viable CICNT layer. The 321 SS and 316 SS samples with 10nm of chromium were tested in a corrosion experiment.. This was done by placing the samples in 1ml of phosphate buffered saline and leaving them in an incubator for 48 hours. We found that all the samples with CICNTs suffered from dramatic corrosion regardless of the added chromium, while the controls without CICNTs experienced no corrosion. This experiment determined that adding a chromium layer does not improve corrosion resistance in CICNT coated SS. We also found that it is not possible to grow viable CICNTs on SS coated with more than 10nm of chromium using a direct growth process. CICNT coated metals continue to show promise for biomedical applications; however, the problems with corrosion of CICNT coated SS are not resolved by the addition of a chromium film.