Tribological Behavior of Z-axis Carbon Fiber in Gas Turbine Engines

The conditions in which materials are expected to operate in the next generation of gas turbine engines are becoming increasingly more challenging. Proper selection of materials is thus critical to increase the lifetime operation of components within the engine. Owing to their high strength properties and their light weight, Polymer Matrix Composites (PMC) are considered to be cost-effective alternatives to conventional metals or alloys. However, under harsh environments, the lifetime of conventional PMCs can be limited by mechanical and tribological properties such as friction and wear. With the recent advancement of Z-axis Carbon Fiber composites, this technology has shown to be promising for improving tribological applications in gas turbine engines. The ZRT film is developed by means of vertically orienting sub-millimeter carbon fibers using a novel process to produce thin films of Z-axis aligned carbon fibers in a polymer matrix. In the present study, the tribological behavior of conventional standard modulus carbon fiber/PEEK unidirectional tape (Toray Cetex® TC1200) was compared with Boston Materials ZRT™/PEEK film under various loading conditions and over time to fully capture their capabilities for the purpose of long-lasting gas turbine engines. Subsequently to the testing, the worn surfaces were critically examined by ex situ analysis to reveal the interfacial phenomena by means of Scanning Electron Microscopy (SEM) as well as confocal laser scanning microscopy (CLSM). A correlation between the fiber orientation of milled carbon fibers and the wear and friction performance was established based on the different study parameters. Emphasis will be made on the strong beneficial of the alignment of the fibers in the Z-axis direction.