82 research outputs found
Influence of metallic and oxidized iron/steel on the reactivity of triphenyl phosphorothionate in oil solution
No full textThe influence of metallic and oxidized iron/steel on the reactivity of triphenyl phosphorothionate (TPPT) in oil solution at 473 K was investigated by means of FT-IR, NMR and XPS. The FT-IR and NMR results show that the degradation of TPPT was catalyzed by metallic and oxidized iron powder and started with the breakage of the P=S bond to form triphenyl phosphate (TPP). The results of the XPS sputter depth profile show the multilayer structure of the thermal film formed on 100Cr6 steel filings immersed for 72 h in TPPT solution heated at 473 K
La storia e il progetto: ipotesi di riqualificazione ambientale per il territorio di Mesola e Goro
No full textRicerca che ha lo scopo di sperimentare forme di progettazione integrata di manufatti, percorsi, misure di salvaguardia e di valorizzazione di un sistema ambientale ad elevato valore storico-documentale. Si ipotizza il mantenimento delle attività connesse con le coltivazioni e la trasformazioni dei prodotti agricoli, come condizione di fattibilità economica, ma soprattutto come fulcro per la condivisione collettiva dei valori culturali da preservare
In Situ Attenuated Total Reflection (ATR/FT-IR) Tribometry: A Powerful Tool for Investigating Tribochemistry at the Lubricant–Substrate Interface
No full textTo investigate the chemical changes occurring at metal/lubricant interfaces under tribological conditions in the boundary-lubrication regime, an in situ system for conducting quantitative tribological measurements has been constructed by combining an attenuated total reflection Fourier-transform infrared (ATR/FT-IR) spectrometer with a reciprocating tribometer. By periodically acquiring ATR/FT-IR spectra during sliding, spectroscopic changes due to thermal and/or tribochemical reactions occurring at the metal/oil interface can be monitored and correlated with friction measurements. The usefulness of this tribological test system has been demonstrated by performing ATR tribological experiments in the presence of a poly-α-olefin base oil at high temperature (423 K) on iron-coated germanium ATR crystals
Substituent Effect on the Reactivity of Alkylated Triphenyl Phosphorothionates in Oil Solution in the Presence of Iron Particles
No full textISSN:1023-8883ISSN:1573-2711ISSN:1573-271
Tribochemistry of Triphenyl Phosphorothionate (TPPT) by In Situ Attenuated Total Reflection (ATR/FT-IR) Tribometry
No full textThe surface reactivity of triphenyl phosphorothionate (TPPT) on air-oxidized iron surfaces under tribological conditions in the boundary-lubrication regime has been investigated by in situ attenuated total reflection (ATR) FT-IR tribometry and ex situ X-ray photoelectron spectroscopy (XPS). In situ ATR/FT-IR tribometry allowed the measurement of the friction force during the tribological tests and its correlation with ATR/FT-IR results, providing an insight into the chemical reactions taking place at the buried interface. The TPPT molecule, which did not behave as a friction-modifier additive, reacted at the air-oxidized iron surface upon tribotesting at 423 K to give pyrophosphate, organo-phosphate, and sulfate species. The oxygenated compounds produced by the oxidation of the base oil (poly-α-olefin, PAO) during the tribological tests, adsorbed onto the iron surface and reacted with it to form carbonates and carboxylates. During the tribotests, the iron coating was worn away and corroded by the aggressive species formed during the thermo-oxidative aging of PAO. This resulted in the availability of iron cations necessary for the production of orthophosphate compounds. The ATR/FT-IR results also suggested that the rate of tribofilm formation was lower than that of tribofilm removal. The ex situ XPS analysis corroborated the formation of short-chain iron polyphosphates, organo-phosphates, and iron sulfates, together with carbonates and carboxylates. Long-chain polyphosphates and sulfoxides were also generated in the boundary lubricant layers formed by TPPT at 423 K. The composition of the tribofilms formed by TPPT was found to differ significantly from that of the boundary layers generated by ZnDTP
Pulse plating of sacrificial Mn-Cu alloys from sulphate bath
No full textPulse plating of manganese-copper alloys from a sulphate solution with the addition of ammonium sulphate at pH 6-7 has been studied. The Mn-Cu electrodeposition system is characterised by steady state and transient electrokinetic methods. The influence of pulse current on cathodic efficiency, microstructure and morphology of the deposits was analysed and compared with the results achieved with continuous current. When short off-times are applied, a uniform and homogeneous morphology is obtained. All the deposits exhibit suitable mechanical properties and low copper content (<5 wt-%). The codeposition of copper prevents the phase transformation of as deposited ductile γ-Mn to the brittle and hard α-Mn for up to a few months
Chemical Reactivity of Triphenyl Phosphorothionate (TPPT) with Iron: An ATR/FT-IR and XPS Investigation
No full textThe surface reactivity of triphenyl phosphorothionate (TPPT) on air-oxidized iron surfaces has been studied by in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR/FT-IR) and ex situ X-ray photoelectron spectroscopy (XPS). The ATR/FT-IR spectra indicate that a reaction took place at 423 K on the iron-coated germanium ATR crystal with the formation of pyrophosphates, organophosphates, and sulfates. The oxidation of the base oil (poly-a-olefin, PAO) during thermal testing, leading to the production of oxygenated compounds that can adsorb onto the iron surface and react with it, resulted in the presence of carbonates and carboxylates in the film. As the heating time increased, the corrosion of the iron coating by the aggressive species formed during the thermooxidative aging of PAO provided the cations necessary for the formation of orthophosphate compounds. The subsequent ex situ XPS analysis, besides substantiating the formation of short-chain polyphosphates, organophosphates, and sulfates on the air-oxidized iron surface, indicates the presence of oxygenated organic compounds in the outermost part of the reaction layer. Modeling the ATR/FT-IR system allowed the correlation of the changes observed in the experimental ATR/FT-IR spectra with the reflectivity alterations caused by the formation of reaction products on the iron-coated germanium ATR crystal. On the basis of these findings, a mechanism for the reaction of TPPT at the oil/iron oxide interface has been proposed
Reactivity of Triphenyl Phosphorothionate in Lubricant Oil Solution
No full textISSN:1023-8883ISSN:1573-2711ISSN:1573-271
Chain-Length-Identification Strategy in Zinc Polyphosphate Glasses by Means of XPS and ToF-SIMS
No full textThe surface chemistry of amorphous zinc polyphosphates of different compositions (ranging from zinc metaphosphate to zinc orthophosphate) has been investigated by means of X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectroscopy (ToF-SIMS). The identification of the chain length of zinc polyphosphates by XPS could be achieved on the basis of the integrated intensity ratio of the bridging (P-O-P) and non-bridging (P=O and P-O-M) oxygen peaks used for fitting the oxygen 1s signal, the shift of the P 2p3/2 signal towards lower binding energies, and of the modified Auger parameter towards higher values as the zinc content increases. The discrimination of the polyphosphate chain lengths could be also achieved by ToF-SIMS, by comparing the intensities of selected characteristic phosphate fragments. Both techniques appear to be suitable for the investigation of polyphosphate glasses in applications such as tribology, where there is a need to identify the chain length present in the outermost monolayer of the film.
Fourier-transform infrared (FT-IR) spectroscopy was used in order to characterize the bulk compounds. The FT-IR studies showed that long-chain structures linked through P-O-P bonds predominate in the metaphosphate composition, while upon increasing the Zn content, the chains become shorter, ultimately being replaced by PO4 monomers in the orthophosphate composition
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