Research On Matching Performance Of Nitriding Cylinder Liner And Three Typical Piston Rings

In recent years,diesel engines have gradually developed in the direction of light weight,compactness,environmental protection and high power.The 3 8CrMoAl nitriding cylinder liner is characterized by high strength,light weight and small volume,which meets the requirements of lightweight and compact of diesel engines,environmental protection requires lower power consumption of diesel engines,so it is necessary to find a piston ring matched with the 38CrMoAl nitriding cylinder liner so that the friction pair composed of the two has better friction reduction,the increase in diesel engine power exacerbates the wear and scuffing tendency of friction pair,so the wear resistance and anti-scuffing performance of the friction pair are also required to be good.Chromium nitride(CrN)piston rings,chromium-based diamond composite plating(GDC)piston rings,and chromium-based ceramic composite plating(CKS)piston rings are three typical piston rings with good tribological properties,it is necessary to carry out the matching research between these three piston rings and 38 CrMoAl nitriding cylinder liner,providing a theoretical basis for material selection and control of friction and wear of cylinder liner-piston ring friction pair of high power density diesel engine.In this paper,the reciprocating tester of friction and wear was used to explore the matching performance of 38CrMoAl nitriding cylinder liner and CrN piston ring,GDC piston ring and CKS piston ring,revealing the influence law of temperature and load on the friction coefficient of three paired pairs,the influence law of load and worn time on the worn amount and worn rate of three paired pairs,and the comparison of anti-scuffing time of three paired pairs,the morphology of three paired pairs after the test was analyzed.The results obtained were as follows:1.When the load was 20MPa to 80MPa and the temperature was 120℃ to 180℃,the friction coefficient of the three paired pairs decreased first and then increased with the increase of the load,the friction coefficient of the three paired pairs decreased slightly with the increase of temperature.As the load increased,the worn amount of the three paired pairs increased,when the load was greater than 60 MPa,the worn rate(the worn amount of per unit load)of the CKS piston ring and the GDC piston ring had a tendency to rise suddenly,the worn rate of the CrN piston ring(the worn amount of per unit load)was gradually decreased.As the worn time increased,the worn amount of the three paired pairs increased,the worn rate(the worn amount of per unit time)was gradually decreased.2.Under the experimental conditions of this paper,the friction coefficients of three paired pairs were sorted as follows:CrN piston ring-nitriding cylinder liner paired pair>GDC piston ring-nitriding cylinder liner paired pair>CKS piston ring-nitriding cylinder liner paired pair;the worn amount of cylinder liner were sorted as follows:cylinder liner matched with CrN piston ring>cylinder liner matched with GDC piston ring>cylinder liner matched with CKS piston ring;the worn amount of piston ring were sorted as follows:CKS piston ring>GDC piston ring>CrN piston ring;the anti-scuffing time of three paired pairs were sorted as follows:CrN piston ring-nitriding cylinder liner paired pair>GDC piston ring-nitriding cylinder liner paired pair>CKS piston ring-nitriding cylinder liner paired pair.3.The mechanism of friction reduction of the friction pair was related to the tribochemical reaction;The worn mechanism of the nitriding cylinder liner was that the contact surface of cylinder liner was firstly deformed and the area of the load bearing platform gradually became larger until a stable contact surface was formed,fatigue shedding occurred in the edge of the bearing platform under the repeated action of contact stress,in turn,the surface area of the entire load bearing platform was gradually reduced,the height of the carrying platform was also gradually decreased.The scuffing mechanism of the three paired pairs was related to adhesive wear and shear damage.