重型柴油机缸体用蠕墨铸铁边界磨损行为研究OA

Vermicular graphite cast irons(VGIs)with vermicularity values of 10％,53％,and 100％were fabricated by adding varying amounts of Fe-Si-Mg vermicularizing agents.The boundary friction and wear behavior between the piston ring assembly and the VGI cylinder block was simulated using an Rtec-MFT5000 tribometer.The results indicate that a VGI with 100％vermicularity is achieved with the addition of 0.102 wt.％vermicularizing agent,which exhibits a specific wear rate of 0.138×10-15m3·N-1·m-1.The wear resistance of the VGI is decreased by approximately 40.8％with increasing vermicularity.The worn-off graphite particles alter the wettability between the boundary layer and the VGI surface,evidencing by a decrease in the contact angle from 23.713° to 13.870°,a reduction scale of approximately 41.5％,which consequently impairing the friction-reducing function of the boundary layer.The dominant wear mechanism is identified as micro-cutting,accompanied by fatigue spalling.Furthermore,with increasing vermicularity,the depth of the ploughing grooves is increased,and the surface roughness is decreased by 3.6％.