{"paper":{"title":"Defects, Corrugation and Temperature Govern Rarefied-Air Drag on Graphene Coatings","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"Coating alumina with graphene reduces the tangential momentum accommodation coefficient of nitrogen, lowering drag in rarefied air.","cross_cats":["physics.chem-ph","physics.flu-dyn"],"primary_cat":"cond-mat.mtrl-sci","authors_text":"Antimo Marrazzo, Davide Bidoggia, Maria Peressi, Samuel Cajahuaringa","submitted_at":"2026-01-30T20:14:33Z","abstract_excerpt":"In rarefied atmospheric environments, where continuum fluid dynamics breaks down, aerodynamic drag is governed by gas-surface momentum exchange, making surface structure and chemistry key design knobs. Using molecular dynamics simulations, we show that coating the $\\alpha$-Al2O3(0001) surface with graphene markedly reduces the tangential momentum accommodation coefficient (TMAC) of N2, shifting scattering toward more specular reflection and thereby lowering drag; we further benchmark this response against graphite. The reduction strengthens up to 900 K. While structural defects can increase TM"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"coating the α-Al2O3(0001) surface with graphene markedly reduces the tangential momentum accommodation coefficient (TMAC) of N2, shifting scattering toward more specular reflection and thereby lowering drag; the reduction strengthens up to 900 K. While structural defects can increase TMAC via defect-induced corrugation and local atomic and electronic rearrangements, graphene retains its performance at experimentally relevant defect densities.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The molecular dynamics simulations provide an accurate representation of the real-world gas-surface momentum exchange for N2 on graphene-coated alumina, including the effects of temperature and defects.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Graphene coating on alumina reduces TMAC of N2 in rarefied conditions, lowering drag, with the effect strengthening to 900 K and remaining robust to defects.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Coating alumina with graphene reduces the tangential momentum accommodation coefficient of nitrogen, lowering drag in rarefied air.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"ca6f436407fbf8a4be8a8fad7b977f9105cf12933e62bd313f656ef58c030ce4"},"source":{"id":"2602.00285","kind":"arxiv","version":3},"verdict":{"id":"4a78897a-e7c6-4b11-a3f6-b405aa15d310","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-16T09:04:20.291111Z","strongest_claim":"coating the α-Al2O3(0001) surface with graphene markedly reduces the tangential momentum accommodation coefficient (TMAC) of N2, shifting scattering toward more specular reflection and thereby lowering drag; the reduction strengthens up to 900 K. While structural defects can increase TMAC via defect-induced corrugation and local atomic and electronic rearrangements, graphene retains its performance at experimentally relevant defect densities.","one_line_summary":"Graphene coating on alumina reduces TMAC of N2 in rarefied conditions, lowering drag, with the effect strengthening to 900 K and remaining robust to defects.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The molecular dynamics simulations provide an accurate representation of the real-world gas-surface momentum exchange for N2 on graphene-coated alumina, including the effects of temperature and defects.","pith_extraction_headline":"Coating alumina with graphene reduces the tangential momentum accommodation coefficient of nitrogen, lowering drag in rarefied air."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2602.00285/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":2,"snapshot_sha256":"4921788eacd5e1d3787dff13e6e853972fc82527b9507946eaf8d0669b6a01f7"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}