What is the general material of the star wheel of a single screw non-oil-water lubricated air compressor

There are many choices of star wheel materials for single screw oil-free and water-lubricated air compressors, including engineering plastics, phenolic resin plus glass fiber, epoxy resin plus glass fiber cross-weaving, self-lubricating aviation grade composite carbon fiber/ductile epoxy resin matrix imported from Britain, and metallic wear-resistant composite cast iron support body. The choice of these materials will affect the wear resistance, life of the star wheel and the performance of the air compressor. Please note that with the development of technology and the update of materials, more new materials may be applied to star wheel manufacturing in the future.