Hard surface coating experimental evaluation and thermomechanical analysis of a seal with micro heat exchanger

Abstract

Mechanical face seals are important components of many rotating machinery. Minimizing the friction between seal faces and efficiently removing the heat generated between seal surfaces are two crucial considerations in the design of mechanical seal. Thin film coating and MEMS technology hold great promise for improving the performance of mechanical seals from the viewpoint of reducing friction and heat at the interface in these two aspects. To reveal what effect the coating and MEMS technology can have on tribological properties of seals, friction and wear characteristics of Ti-C:H coatings on seal-like rings and heat transfer performances of a seal prototype implanted with micro heat exchangers were studied in this thesis. Implanted micro-heat exchangers were built using the MEMS technology in a previous work. Coating on seal-like rings was successfully implemented using CVD/PVD Friction and wear properties of coatings with different compositions were investigated through a series of unlubricated ring-on-disk experiments in a tribometer. The results showed the Ti-C:H coatings tend to improve the tribological performance. However, the experimental results did not reveal a direct relationship between coating composition and its tribological properties. Micro posts implanted seal prototype had been manufactured and tested in a previous work. In the present study, a finite element model was developed to simulate the experiment and evaluate the heat transfer characteristic of the seal prototype. The predictions of the model are in good agreement with the measured results. In addition, a method was developed for the calculation of the seal structure’s maximum stress under normal friction load. This method can be used for the structural analysis and failure prediction of seals with micro posts.