Surface Engineering & Tribology Laboratory at Oak Ridge National Laboratory
Facility Overview
The Surface Engineering and Tribology Laboratory facility at Oak Ridge National Laboratory provides a bench-scale systematic evaluation of candidate lubricants and bearing/gear materials of the voucher recipient’s interest for advancing the efficiency and durability of marine turbomachinery. Tribological behavior is highly dependent on the operating/testing conditions, and thus the key in tribological evaluation is to identify/design appropriate tests with high relevancy to the actual application.
In each voucher, tribosystem analysis is first conducted to understand the application needs and learn the critical attributes of the actual contact interface including the surface compositions, mechanical properties, and topography, lubricant viscosity and chemistry, temperature, contact pressure, relative motion, and velocity. Then, appropriate tribological tests including ASTM standards are identified and testing protocols are designed to best simulate the actual contact interface. A test matrix is then defined with at least 2-3 repeat tests at each condition. The lubricant viscosity and thermal stability, surface hardness and roughness, and the contact angle of the lubricant on the surface are measured before tribo-testing. The friction coefficient is monitored in situ. The wear loss is quantified using a 3D white interferometer and the surface damage is examined using optical and electron microscopes. Tribofilm characterization is used to learn the lubricant-surface compatibilities. Outcomes include the tribological performance of the candidate lubricants or materials/coatings of interest, side-by-side comparison with relevant commercial baselines, and mechanistic understanding. Monthly meetings are held between the ORNL team and the voucher recipient for work planning, progress update, and discussion. A final report is provided to summarize the testing results with scientific interpretation.
Bench testing and characterization capabilities
- Tribosystem analysis for understanding the failure modes and wear mechanisms
- Contact interface modeling: Contact mechanics, heat transfer, and lubrication modeling
- Materials characterization: Microstructure, composition, morphology, roughness, and mechanical and thermophysical properties
- Materials and lubricants development for mitigation
- Novel lubricants and additives: Ionic liquids, molten salts, and nanoparticles
- Advanced coatings/surface treatments: CNT coatings, oxygen diffusion, friction stir processing, and additive manufacturing
- Standardization: Four ASTM standards for tribo-testing have been developed at ORNL
- Tribological testing
- Various wear modes: Abrasive (2-body & 3-body) wear; Sliding wear; Rolling contact fatigue; Fretting
- Capable of testing under boundary, mixed, and elastohydrodynamic lubrication, simulating the bearing and gear contacts in hydro or tidal turbines under wide operating conditions
- > 15 tribometers including PCS Instruments Micropitting Rig for rolling-sliding, Plint TE-77 reciprocating sliding (ASTM G 133), AMTI unidirectional sliding (ASTM G99), VLBT (simulating journal bearings and generating Stribeck curves), and Loop Abrasion tester (ASTM G 174)
- Well-controlled conditions: Ambient, vacuum, or controlled gas; RT – 1000 oC; 0.1 – 1000 N load; 0.1 mm/s – 15 m/s velocity; Dry, wet, & lubricated
- Lubricant analysis
- Viscometer (MINIVIS II), FTIR (Frontier LR 64912C), TGA (TA Instrument TGA 2950 & DSC Q100), and contact angle meter (Dataphysics OCA 25)
- Multi-scale hardness measurements
- Rockwell, Vickers and Knoop microindentation, and TriboIndenter nanoindentation
- Surface topographical, roughness, energy, morphological, and compositional characterization
- Wyko NT9100 3D white light interferometer for wear quantification and Mahr 2D profiler for roughness measurement
- Contact angle meter (Dataphysics OCA 25) for surface energy quantification
- SEM, EDS, XPS, and FIB-aided TEM/STEM for worn surface and tribofilm characterization
