Tribo-Characteristics of Cryogenic Hybrid Ceramic Ball Bearings for Rocket Turbopumps: Self-Lubricating Performance©

Cryogenic Tribology in High-Speed Bearings and Shaft Seals of Rocket Turbopumps

“…To the contrary, the all-steel bearing indicated excellent load capacity accompanied by a stable bearing and enabled to sustain a thrust load of 2,650 N (Smax, 2.7 GPa) at a speed of 50,000 rpm without seizure in LO 2 [39].…”

“…Furthermore, even when bearing torque increased with a rise of bearing temperature, the hybrid ceramic bearing was able to sustain a thrust load of 2,840 N (Smax, 3.2 GPa) at 50,000 rpm without seizure in LH 2 . High critical load capacity of the single-guided hybrid ceramic bearing was demonstrated [39]. Tribology -Fundamentals and Advancements Figure 23 shows the XPS depth analysis of a Si 3 N 4 ball taken from the hybrid ceramic bearing tested in LH 2 [27].…”

“…In order to improve internal coolant flow through the bearing and to reduce bearing frictional torque, a new type of bearing having a single-guided retainer was developed. Figure 21 shows the 25-mm-bore bearing having a single-guided retainer with elliptical ball pockets [39]. The singleguided retainer is guided only by one side of the outer-ring bore (land) to reduce land friction and to increase the cooling ability within the bearing.…”

“…6.1.1. Self-lubricating performance and transfer film [27,39] a. In LH 2 Figure 22 shows the bearing torque of the single-guided bearings (hybrid ceramic bearing and all-steel bearing) and the conventional double-guided bearing at speeds to 50,000 rpm in LH 2 [39].…”

“…Self-lubricating performance, bearing wear and transfer film of two-types of the single-guided bearing, i.e., a hybrid ceramic bearing with Si 3 N 4 and all-steel bearing, was evaluated under high thrust loads at speeds up to 50,000 rpm in LH 2 , LO 2 and LN 2 [27,39]. Furthermore, to evaluate the durability of the single-guided bearing for long-life bearing, the all steel bearing was tested for total operation times up to 11.7 hours at a speed of 50,000 rpm with high thrust loads in LO 2 [28].…”