A pin-on-disc study of the tribology characteristics of sintered versus standard steel gear materials

Abstract

a b s t r a c tThough powder metallurgy (PM) allows manufacturing of complex components, including gears, we lack knowledge of the tribological performance of PM versus standard steel gear materials. Using a pin-ondisc machine, we simulate the sliding part of gear tooth contact in boundary and mixed lubricated regions, comparing the tribological characteristics of two sintered gear materials with those of a standard gear material. The comparison considered damage mechanisms, wear, and friction between these materials in different configurations (i.e., standard versus standard, sintered versus sintered, and sintered versus standard). The results indicate that, for pairings of the same gear materials, i.e., RS-RS (16MnCr5), AQ-AQ (Distaloy AQ þ 0.2% C), and Mo-Mo (Astaloy 85Mo þ0.2% C), RS has a lower friction coefficient. For PM and RS combinations, both PM pins have lower friction coefficients with RS disc material than do RS pins with PM disc materials. For the wear coefficient, at low and high speeds, RS pins always display better wear resistance than do AQ or Mo pins because of their high hardness and compacted microstructure. For RS-PM combinations, Mo pins display higher wear resistance than do AQ pins because their larger and more numerous pores enable good lubrication. Pins in the Mo-RS combination displayed the highest wear resistance, mainly because the pores in Mo discs hold lubricant, lubricating the contact surface and preventing adhesive wear. For the RS pin in the Mo-RS combination and the AQ pin in RS-AQ, the damage mechanism is slight adhesive wear and scuffing. For pins in the PM-PM, RS-PM, AQ-RS, and RS-RS combinations, the damage mechanism is a heavier scuffing-type adhesive wear.

Pin-on-Disc Study of Tribological Performance of Standard and Sintered Gear Materials Treated with Triboconditioning Process: Pretreatment by Pressure-Induced Tribofilm Formation

“…In this experiment only the disc was coated because it was difficult to apply the special procedure to the pin tip given its hemispherical shape. more information is available in [14]. Porosities on or near the surface influence the friction and wear coefficients [14].…”

FZG Gear Efficiency and Pin-on-Disc Frictional Study of Sintered and Wrought Steel Gear Materials

“…Each test was performed twice to ensure repeatability. The test results from 900 MPa were previously presented in Li et al [13]. For the higher maximum contact pressure of 1080 MPa, the speed ranges were chosen differently to explore more of the boundary lubrication regime.…”

“…The main reason is probably that the porosities on the AQ component act as surface roughness, providing more opportunities for asperity contact [13].…”

“…The different alloying elements used in powder metallurgy materials may also influence the surface layer and help prevent adhesive forces. Recently, Li et al [13] compared sintered and standard gear materials in a pin-on-disc study simulating the loading conditions of load stage 5 in a FZG gear test rig. The results showed that the lowest coefficient of friction was obtained with a sintered pin sliding on a standard wrought gear material disc, compared to tests with sintered on sintered contacting pairs and also standard wrought on standard wrought gear material.…”

“…In this study, a further test of the results of Li et al [13] was set up in a FZG efficiency gear test rig. In this test series, the efficiency was evaluated over a wider speed range but for the same maximum contact pressure as previous pin-on-disc tests using the same material combinations.…”