Abstract:Layered
sodium silicates β-Na2Si2O5 and kanemite were synthesized via facile methods under mild
conditions. The tribological properties of β-Na2Si2O5 and kanemite utilized as additives in lithium
grease were evaluated with a four-ball tester under different experimental
conditions. The maximum nonseizure load value of 5.0 wt % β-Na2Si2O5 grease jumped from 353 N (the
base grease) to 1568 N. However, 5.0 wt % MoS2 grease
could only reach 617 N under the same conditions. The SEM and EDS
results confirm that a pr… Show more
“…Supplementary Figure S8 shows the results for the PAO8 lithium-based grease, which are consistent. These results suggest that the layered phosphates with corrugated layers as lubrication additives may form protective films on friction pairs, thereby increasing the lubricating ability, in agreement with the results for β-LDS and α-ZrP in our previous study 8,10 .Figure 7Analysis of the rubbing surface after long run (3600 s) friction-wear testing. ( a ) Non-contact 3D.…”
Section: Resultssupporting
confidence: 88%
“…β-LDS was synthesized according to literature 8 , Silicates powder (5 g) was put into a stainless-steel autoclave, and heated at 260 °C for 45 min in a muffle furnace. After cooling the autoclave to room temperature, the solid products were obtained.…”
Lubricating technologies are essential for saving energy and identifying effective, environmentally friendly layered materials that meet the demands of solid lubricants is an important direction. Herein, we probed the relationships between load-carrying capacity and crystal structure. The results showed that increasing the sliding resistance of interlayers using corrugated layers increased the load-carrying capacity of layered solid lubricants. This finding expands on the traditional lubrication mechanism of layered materials. Following the rules, rapid selection of layered potassium magnesium and calcium phosphates (K-LMP and K-LCP) as effective solid lubricants was achieved using crystallographic data and strict filtering criteria. In order to prepare materials suitable for lubrication, the synthesis of K-LMP and K-LCP was optimised. These materials could be utilised in the food, textile or marine machinery industries in the future. The developed method could successfully guide the synthesis of application-oriented materials.
“…Supplementary Figure S8 shows the results for the PAO8 lithium-based grease, which are consistent. These results suggest that the layered phosphates with corrugated layers as lubrication additives may form protective films on friction pairs, thereby increasing the lubricating ability, in agreement with the results for β-LDS and α-ZrP in our previous study 8,10 .Figure 7Analysis of the rubbing surface after long run (3600 s) friction-wear testing. ( a ) Non-contact 3D.…”
Section: Resultssupporting
confidence: 88%
“…β-LDS was synthesized according to literature 8 , Silicates powder (5 g) was put into a stainless-steel autoclave, and heated at 260 °C for 45 min in a muffle furnace. After cooling the autoclave to room temperature, the solid products were obtained.…”
Lubricating technologies are essential for saving energy and identifying effective, environmentally friendly layered materials that meet the demands of solid lubricants is an important direction. Herein, we probed the relationships between load-carrying capacity and crystal structure. The results showed that increasing the sliding resistance of interlayers using corrugated layers increased the load-carrying capacity of layered solid lubricants. This finding expands on the traditional lubrication mechanism of layered materials. Following the rules, rapid selection of layered potassium magnesium and calcium phosphates (K-LMP and K-LCP) as effective solid lubricants was achieved using crystallographic data and strict filtering criteria. In order to prepare materials suitable for lubrication, the synthesis of K-LMP and K-LCP was optimised. These materials could be utilised in the food, textile or marine machinery industries in the future. The developed method could successfully guide the synthesis of application-oriented materials.
“…Hence, this class of materials, when included in the matrix as an SL, offers notable anti-friction capability [ 3 ]. Layered sodium silicates such as δ-Na 2 Si 2 O 5 , α-Na 2 Si 2 O 5 , β-Na 2 Si 2 O 5 , and kanemite represent another group of relatively inexpensive materials to reduce wear due to their layered structure similar to other transition-metal dichalcogenides [ 40 ]. The widely known materials of this category include graphene, graphite, hexagonal boron nitride (hBN), TMDs, and particularly MoS 2 and WS 2 ( Figure 5 ).…”
Understanding the complex nature of wear behavior of materials at high-temperature is of fundamental importance for several engineering applications, including metal processing (cutting, forming, forging), internal combustion engines, etc. At high temperatures (up to 1000 °C), the material removal is majorly governed by the changes in surface reactivity and wear mechanisms. The use of lubricants to minimize friction, wear and flash temperature to prevent seizing is a common approach in engine tribology. However, the degradation of conventional liquid-based lubricants at temperatures beyond 300 °C, in addition to its harmful effects on human and environmental health, is deeply concerning. Solid lubricants are a group of compounds exploiting the benefit of wear diminishing mechanisms over a wide range of operating temperatures. The materials incorporated with solid lubricants are herein called ‘self-lubricating’ materials. Moreover, the possibility to omit the use of conventional liquid-based lubricants is perceived. The objective of the present paper is to review the current state-of-the-art in solid-lubricating materials operating under dry wear conditions. By opening with a brief summary of the understanding of solid lubrication at a high temperature, the article initially describes the recent developments in the field. The mechanisms of formation and the nature of tribo-films (or layers) during high-temperature wear are discussed in detail. The trends and ways of further development of the solid-lubricating materials and their future evolutions are identified.
“…In recent years, silicate glasses have appeared as bright candidates for lubrication in harsh conditions because of their exceptional thermal stability, low cost, and environmentally friendly properties . This kind of lubricant can provide superb friction reduction and antiwear properties at high temperatures. − In addition, silicate-based compounds have self-restoration capabilities which can repair the mechanical damage at the bearing surfaces . Although a number of experiments have been carried out to investigate the frictional behaviors and characterizations of a silicate glass tribofilm at macroscopic scales, the formation mechanisms as well as the chemical insight into the iron–silicate tribofilm still remain unclear.…”
Silicate
glasses are potential materials for lubrication at elevated
temperature because of their exceptional thermal stability, low cost,
and environmentally friendly properties. Although the frictional behaviors
and characterizations of silicate glass tribofilms have been studied
by a number of experiments, the formation mechanisms as well as the
chemical insight into the iron–silicate tribofilm still remain
unclear. In the present study, the adsorption and depolymerization
of the sodium sorosilicate cluster Na6Si2O7 on a Fe(110) surface have been studied using both first-principles
molecular dynamics and density functional theory. Comparisons of adsorption
processes and electronic structure of some typical configurations
at different temperatures have been carried out. The results strongly
suggest that the silicate cluster chemically adsorbs on the Fe(110)
surface by forming multiple Fe–nonbridging oxygen (NBO) bonds.
The iron surface plays an important role in the dissociation of the
NBO by significantly reducing the strength of Si–NBO bonds.
Electronic structure calculation reveals that the charge transfer
between the lubricant and the iron surface during the adsorption may
lead to a flow of alkali ions and a layering process in the tribofilm.
Depolymerization is observed at higher temperature and has larger
activation energy compared to Si–NBO dissociations, indicating
that the process is more difficult. Temperature is also an important
factor that contributes to the dissociation of NBOs as well as the
depolymerization of the lubricant, both of which can have several
impacts on the lubricity of the tribofilm. This study provides a detailed
understanding of the chemical reaction of sodium polysilicate on the
iron surface at high temperature.
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