Comparative Study on the Thermal and Tribological Properties of PA12 and PA11 for Coating Applications

In this study, the performance and potential applicability of polyamide-12 (PA12) as an alternative to polyamide-11 (PA11), which is currently used in the coating processes of sliding tools present in cardan shafts, was investigated. The advantages of PA12 powder instead of PA11 in cardan shafts' coating include ease of supply and cost-effectiveness, while still achieving similar performance. Therefore, PA12 is a more economical choice for coating applications. The PA11 and PA12 neat polymers were characterized via differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Based on the analyses, PA12 demonstrated substantial advantages over PA11. It showed a 16 degrees C improvement in decomposition temperature and a 50% increase in crystallinity, enhancing stability under operational conditions, whereas PA11 exhibited approximately 6-7% higher values in crystallization and melting temperatures. The wettability behavior of the steel substrates coated with those polyamides was measured via contact angle analysis. Wear properties and morphologies of coatings were examined using a ball-on disc test and scanning electron microscopy, respectively and comparatively. Furthermore, PA12 typically displays 30% lower wear rates and similar deformation patterns in tests, thereby presenting itself as a cost-effective and widely accessible option for coating applications in comparison to PA11.