Performance of fullerene-like CNx coatings for automotive valve-train applications
(English)Manuscript (Other academic)
The design of internal combustion engines is evolving in order to provide greater efficiency and lower harmful emissions. There has been a move to lower component masses, higher engine temperatures, lower viscosity oils and low SAPS (sulphated ash, phosphor and sulphur) oils. With the transition to low density, low hardness materials and new lubrication conditions, come issues of component wear. Surface engineering techniques such as thin-film coating technologies present a possible solution. Thin-film coating development in recent years has often focused on achieving a high hardness, which often leads to high elastic modulus. However, there are potential benefits of less stiff and more elastic coatings. A number of wear mechanism are directly related to the ratio of hardness (H) and elastic modulus (E) and higher H/E ratios can be beneficial. This work therefore investigates the potential for using a highly elastic, experimental fullerene-like carbon nitride (FL-CNx) coating in a valve-train environment. Two FL-CNx coatings of differing nitrogen content were investigated using microscopy, wear testing, nanoindentation testing and in an experimental cam-tappet testing rig. The two FL-CNx coatings had similar adhesion to the substrate and hardness. The FL-CNx coating with the higher value of H/E also showed greater durability in the valve-train testing.
Fullerene-like materials, automotive valve-train, applications
Other Engineering and Technologies not elsewhere specified
IdentifiersURN: urn:nbn:se:liu:diva-17060OAI: oai:DiVA.org:liu-17060DiVA: diva2:201496