Friction-Induced Change of Boron Hybridization in Lubricant Additives
Bibliographic record
Abstract
Tribochemical interactions between antiwear zinc dithiophosphate (Zndtp), friction modifier molybdenum dithiocarbamate (Modtc) and overbased detergent calcium borate (OCB) lubricant additives have been investigated. A Cameron-Plint friction machine was used to generate large tribofilm areas in mild tribological conditions. Two analytical techniques, X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure spectroscopy (XANES), have been employed to characterize the chemical species in tribofilms. XANES spectroscopy at the P K and L-edges, S K-edge, Mo L and M-edges and B K-edge was carried out in order to investigate phosphate, sulfide and borate species in tribofilms. The XANES spectra were recorded in both the total electron yield (TEY), surface sensitive and fluorescent yield (FY), bulk sensitive mode. This was completed with XPS analyses in the same location in the tribofilm. The ternary system Zndtp + Modtc + OCB provides a low wear rate comparable to the binary system Modtc + OCB. XANES analyses have shown that adding OCB to the binary system Zndtp + Modtc increases the formation of MoS2 and reduce the formation of ZnS. It has been seen that few quantity of boron is consumed during the tests, meaning that boron does not react with other additives, we only observe a formation of calcium phosphate. A special attention has been paid on the hybridization of boron (trigonal sp2 and tetrahedral sp3). All tribofilms show a higher proportion of trigonal borate than the additives alone. However, this proportion is the highest in the case of tribofilms produce with the ternary mixture OCB + Zndtp + Modtc. Borate has a planar conformation and could be friction-oriented in the sliding interface. The oriented borate planar molecule might be at the origin of the MoS2 sheets orientation in the ternary system.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".