Ceramic Cam Roller Follower Simulation Tests and Evaluation

Abstract

Two types of ceramic materials, zirconia-toughened alumina (ZTA), and transformation-toughened zirconia (TTZ—yttria stabilized zirconia), were evaluated as cam roller followers in simulated valve train tests and were compared to silicon nitride (Si₃N₄) roller followers. These tests were conducted to determine the short-term durability of these ceramics and to determine their efficacy as cam roller followers. A weight gain of approximately 10⁻⁴ g occurred on each type of ceramic material. This was caused by a polishing action on the driving ring specimen, made of AISI 52100 steel, and the formation of a transfer film. The friction coefficients ranged between 0.041 and 0.071, correlating closely to theoretical predicted values of approximately 0.064. A relative ranking of the materials could only be made by the change in surface roughness on the steel ring, as weight loss was not measured. The asperity tips on the steel rings exhibited a greater amount of polishing wear and lower roughness values when tested against the ZTA and Si₃N₄, while the rings tested against the TTZ ceramics exhibited little wear.

Presented at the 47th Annual Meeting in Philadelphia, Pennsylvania May 4–7, 1992

KEY WORDS:

• Silicon Nitride
• Zirconia-Toughened Alumina
• Yttria-Stabilized Zirconia
• Monoclinic Phase
• Tetragonal Phase
• Ceramics
• Lubricated Tests
• Rolling/Sliding Wear Tests
• X-ray Diffraction
• Transfer Film
• Grain Pullout
• Slide-to-Roll Ratio
• Polishing Wear

Notes

Presented at the 47th Annual Meeting in Philadelphia, Pennsylvania May 4–7, 1992