{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/78320"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/78320","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Tribology of engineering and coated materials in the presence of environmentally friendly refrigerant","abstract":"In recent years, considerable effort has been devoted towards finding of alternative refrigerants due to environmental issues related to high global warming potential (GWP). Specifically, developing a system-compatible alternative refrigerant is of prime concern in order to reduce costs associated with design modifications. Among the candidate refrigerants, newly developed HFO-1234yf is considered as a direct substitution for the current R-134a refrigerant for possessing similar thermo -physical properties. However, in an actual system, a refrigerant circulates through different tribo-components where it interacts with the interfacial components (such as surface materials and lubricants), altering their tribological behavior. Therefore, the tribological performance of a refrigerant must be evaluated prior to widely used in refrigeration/ air-conditioning systems. Along this line, we have investigated the tribological performance of HFO-1234yf refrigerant under aggressive boundary lubrication conditions. Specifically, we have performed controlled tribo-experiments, simulating actual automotive air-conditioning compressor systems, to measure in-situ friction and near-contact temperature. Interestingly, we have observed a run-in instability in the frictional behavior for the case of HFO-1234yf refrigerant, unlike R-134a refrigerant. This intermediate instability is associated with decomposition of the reactive HFO-1234yf refrigerant at the contact interface under specific loading conditions. However, beneficial anti-wear tribofilms were shown to evolve throughout this process as revealed via Scanning Electron Microscopic (SEM) analysis. Energy Dispersive Spectroscopy (EDS) in conjunction with X-ray Photoelectron Spectroscopic (XPS) analysis identified the existence of Fluorine on these boundary films, attributing the fluorinated interaction at the contact zone. This fluorination, thus, facilitates formation of FeF3- enriched tribofilms over the cast iron based interface. In addition, we have demonstrated the influence of the loading conditions and state-or-art lubricants on the tribological compatibility of HFO-123yf refrigerant. Finally, the tribological performance of newly synthesized aromatic thermosetting polyester (ATSP), blended with 5% polytetrafluoroethylene (PTFE), namely ATSP/PTFE, has been evaluated under unlubricated and boundary lubricated conditions. Current state-of-art polymeric coatings have also been considered for comparative purposes. Tribological and morphological investigations revealed superior tribological performance for ATSP/PTFE. The better performance is attributed to segregated surface morphology associated with ATSP/PTFE","abstract_html":"In recent years, considerable effort has been devoted towards finding of alternative refrigerants due to environmental issues related to high global warming potential (GWP). Specifically, developing a system-compatible alternative refrigerant is of prime concern in order to reduce costs associated with design modifications. Among the candidate refrigerants, newly developed HFO-1234yf is considered as a direct substitution for the current R-134a refrigerant for possessing similar thermo -physical properties. However, in an actual system, a refrigerant circulates through different tribo-components where it interacts with the interfacial components (such as surface materials and lubricants), altering their tribological behavior. Therefore, the tribological performance of a refrigerant must be evaluated prior to widely used in refrigeration/ air-conditioning systems. Along this line, we have investigated the tribological performance of HFO-1234yf refrigerant under aggressive boundary lubrication conditions. Specifically, we have performed controlled tribo-experiments, simulating actual automotive air-conditioning compressor systems, to measure in-situ friction and near-contact temperature. Interestingly, we have observed a run-in instability in the frictional behavior for the case of HFO-1234yf refrigerant, unlike R-134a refrigerant. This intermediate instability is associated with decomposition of the reactive HFO-1234yf refrigerant at the contact interface under specific loading conditions. However, beneficial anti-wear tribofilms were shown to evolve throughout this process as revealed via Scanning Electron Microscopic (SEM) analysis. Energy Dispersive Spectroscopy (EDS) in conjunction with X-ray Photoelectron Spectroscopic (XPS) analysis identified the existence of Fluorine on these boundary films, attributing the fluorinated interaction at the contact zone. This fluorination, thus, facilitates formation of FeF3- enriched tribofilms over the cast iron based interface. In addition, we have demonstrated the influence of the loading conditions and state-or-art lubricants on the tribological compatibility of HFO-123yf refrigerant. Finally, the tribological performance of newly synthesized aromatic thermosetting polyester (ATSP), blended with 5% polytetrafluoroethylene (PTFE), namely ATSP/PTFE, has been evaluated under unlubricated and boundary lubricated conditions. Current state-of-art polymeric coatings have also been considered for comparative purposes. Tribological and morphological investigations revealed superior tribological performance for ATSP/PTFE. The better performance is attributed to segregated surface morphology associated with ATSP/PTFE","abstract_has_math":false,"creators":["Akram, Mohammad"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Polycarpou, Andreas A.","Economy, James","Bellon, Pascal","Jasiuk, Iwona","Dunn, Alison"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-07-22T22:15:59Z","date_published":"2015-07-22T22:15:59Z","updated_at":"2026-07-22T22:26:11Z","subjects":["Aromatic Thermosetting Poyester (ATSP)","Polymeric Coatings","Tribofilm","Boundary Lubrication","Tribology","Hydrofluoroolefins (HFO-1234yf)","Environmentally Friendly Refrigerant"],"languages":[],"rights":["Copyright 2015 Mohammad Akram"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/78320","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Polycarpou, Andreas A.","Economy, James","Bellon, Pascal","Jasiuk, Iwona","Dunn, Alison"]},{"key":"dc:creator","label":"Author","values":["Akram, Mohammad"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-07-22T22:15:59Z","2015-05","2015-03-10","2015-5"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Aromatic Thermosetting Poyester (ATSP)","Polymeric Coatings","Tribofilm","Boundary Lubrication","Tribology","Hydrofluoroolefins (HFO-1234yf)","Environmentally Friendly Refrigerant"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2015 Mohammad Akram"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/78320"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["In recent years, considerable effort has been devoted towards finding of alternative refrigerants due to environmental issues related to high global warming potential (GWP). Specifically, developing a system-compatible alternative refrigerant is of prime concern in order to reduce costs associated with design modifications. Among the candidate refrigerants, newly developed HFO-1234yf is considered as a direct substitution for the current R-134a refrigerant for possessing similar thermo -physical properties. However, in an actual system, a refrigerant circulates through different tribo-components where it interacts with the interfacial components (such as surface materials and lubricants), altering their tribological behavior. Therefore, the tribological performance of a refrigerant must be evaluated prior to widely used in refrigeration/ air-conditioning systems. Along this line, we have investigated the tribological performance of HFO-1234yf refrigerant under aggressive boundary lubrication conditions. Specifically, we have performed controlled tribo-experiments, simulating actual automotive air-conditioning compressor systems, to measure in-situ friction and near-contact temperature. Interestingly, we have observed a run-in instability in the frictional behavior for the case of HFO-1234yf refrigerant, unlike R-134a refrigerant. This intermediate instability is associated with decomposition of the reactive HFO-1234yf refrigerant at the contact interface under specific loading conditions. However, beneficial anti-wear tribofilms were shown to evolve throughout this process as revealed via Scanning Electron Microscopic (SEM) analysis. Energy Dispersive Spectroscopy (EDS) in conjunction with X-ray Photoelectron Spectroscopic (XPS) analysis identified the existence of Fluorine on these boundary films, attributing the fluorinated interaction at the contact zone. This fluorination, thus, facilitates formation of FeF3- enriched tribofilms over the cast iron based interface. In addition, we have demonstrated the influence of the loading conditions and state-or-art lubricants on the tribological compatibility of HFO-123yf refrigerant. Finally, the tribological performance of newly synthesized aromatic thermosetting polyester (ATSP), blended with 5% polytetrafluoroethylene (PTFE), namely ATSP/PTFE, has been evaluated under unlubricated and boundary lubricated conditions. Current state-of-art polymeric coatings have also been considered for comparative purposes. Tribological and morphological investigations revealed superior tribological performance for ATSP/PTFE. The better performance is attributed to segregated surface morphology associated with ATSP/PTFE","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-07-22 without embargo terms","The student, Mohammad Akram, accepted the attached license on 2015-02-27 at 22:21.","The student, Mohammad Akram, submitted this Dissertation for approval on 2015-02-27 at 22:36.","This Dissertation was approved for publication on 2015-03-10 at 16:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #7730 on 2015-07-22 at 10:30:14","Made available in DSpace on 2015-07-22T22:15:59Z (GMT). No. of bitstreams: 2 Akram_Mohammad1.pdf: 7005983 bytes, checksum: ea68e4c0b965b77aa129b4fe67c77e98 (MD5) license.txt: 4063 bytes, checksum: ed0f456ce856d3b4086e73e66b2d08e8 (MD5) Previous issue date: 2015-03-10"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Tribology of engineering and coated materials in the presence of environmentally friendly refrigerant"]}]}],"canonical_facts":{"dc:contributor":["Polycarpou, Andreas A.","Economy, James","Bellon, Pascal","Jasiuk, Iwona","Dunn, Alison"],"dc:creator":["Akram, Mohammad"],"dc:date":["2015-07-22T22:15:59Z","2015-05","2015-03-10","2015-5"],"dc:description":["In recent years, considerable effort has been devoted towards finding of alternative refrigerants due to environmental issues related to high global warming potential (GWP). Specifically, developing a system-compatible alternative refrigerant is of prime concern in order to reduce costs associated with design modifications. Among the candidate refrigerants, newly developed HFO-1234yf is considered as a direct substitution for the current R-134a refrigerant for possessing similar thermo -physical properties. However, in an actual system, a refrigerant circulates through different tribo-components where it interacts with the interfacial components (such as surface materials and lubricants), altering their tribological behavior. Therefore, the tribological performance of a refrigerant must be evaluated prior to widely used in refrigeration/ air-conditioning systems. Along this line, we have investigated the tribological performance of HFO-1234yf refrigerant under aggressive boundary lubrication conditions. Specifically, we have performed controlled tribo-experiments, simulating actual automotive air-conditioning compressor systems, to measure in-situ friction and near-contact temperature. Interestingly, we have observed a run-in instability in the frictional behavior for the case of HFO-1234yf refrigerant, unlike R-134a refrigerant. This intermediate instability is associated with decomposition of the reactive HFO-1234yf refrigerant at the contact interface under specific loading conditions. However, beneficial anti-wear tribofilms were shown to evolve throughout this process as revealed via Scanning Electron Microscopic (SEM) analysis. Energy Dispersive Spectroscopy (EDS) in conjunction with X-ray Photoelectron Spectroscopic (XPS) analysis identified the existence of Fluorine on these boundary films, attributing the fluorinated interaction at the contact zone. This fluorination, thus, facilitates formation of FeF3- enriched tribofilms over the cast iron based interface. In addition, we have demonstrated the influence of the loading conditions and state-or-art lubricants on the tribological compatibility of HFO-123yf refrigerant. Finally, the tribological performance of newly synthesized aromatic thermosetting polyester (ATSP), blended with 5% polytetrafluoroethylene (PTFE), namely ATSP/PTFE, has been evaluated under unlubricated and boundary lubricated conditions. Current state-of-art polymeric coatings have also been considered for comparative purposes. Tribological and morphological investigations revealed superior tribological performance for ATSP/PTFE. The better performance is attributed to segregated surface morphology associated with ATSP/PTFE","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-07-22 without embargo terms","The student, Mohammad Akram, accepted the attached license on 2015-02-27 at 22:21.","The student, Mohammad Akram, submitted this Dissertation for approval on 2015-02-27 at 22:36.","This Dissertation was approved for publication on 2015-03-10 at 16:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #7730 on 2015-07-22 at 10:30:14","Made available in DSpace on 2015-07-22T22:15:59Z (GMT). No. of bitstreams: 2 Akram_Mohammad1.pdf: 7005983 bytes, checksum: ea68e4c0b965b77aa129b4fe67c77e98 (MD5) license.txt: 4063 bytes, checksum: ed0f456ce856d3b4086e73e66b2d08e8 (MD5) Previous issue date: 2015-03-10"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/78320"],"dc:rights":["Copyright 2015 Mohammad Akram"],"dc:subject":["Aromatic Thermosetting Poyester (ATSP)","Polymeric Coatings","Tribofilm","Boundary Lubrication","Tribology","Hydrofluoroolefins (HFO-1234yf)","Environmentally Friendly Refrigerant"],"dc:title":["Tribology of engineering and coated materials in the presence of environmentally friendly refrigerant"],"dc:type":["text"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:11Z"}