Friction And Wear Properties Of Alloy Cast Iron Cylinder Liner Of High Power Density Diesel Engine

Cylinder liner-piston ring is the core of friction pair in internal combustion engine. Currently, energy saving and environmental protection have more stringent requirements. As the explosion pressure and rotating speed increasing, the mechanical load and thermal load increased in a large margin on the cylinder liner and piston ring friction pair. The analysis and research of this friction pair is vital significance for the service life and reliability of internal combustion. This paper conducts friction-wear tests and anti-adhesion tests on alloy cast iron cylinder liner and three kinds of surface modification piston rings (CrN piston ring; spraying molybdenum piston ring; CKS piston ring). Friction and wear properties and anti-adhesion properties are studied under different working conditions. The main conclusions are as follows:1)As load increasing, friction coefficient increased after the first decreased. Wear increased slowly at first and then have a rapidly increasing, its trend to stable as the load increased. As temperature increasing, friction coefficient and wear fell slightly. Fiction coefficient and wear from high to low is:cast iron-spraying molybdenum> cast iron-CKS> cast iron-CrN.2) Cast iron-CrN and cast iron-CKS have the similar wear mechanism. There are plastic deformations in contact area at first until it’s become stable. The asperities fall off after plastic deformation under repeated contact stress. The wear mechanism of cast iron-spraying molybdenum is that the transfer particles come into being in contact surface. The transfer particles plough grooves and cracks on the surface after work hardening. The embedded particles tear the surface and become grooves after adhesive. The scuffing mechanism is that the oil film consumption unceasing after oil cut-off. When the production is less than the consumption of the boundary film, the stick point formed at part of the surface. Then it’s enlarged to the whole contact surface.3) Friction coefficient and wear of cast iron-CrN and cast iron-CKS is low at normal. Under the boundary condition, the anti-adhesion performance of cast iron-CKS is better than cast iron-CrN. Cast iron-CrN is the best.