Synergistic effects of 3D porous graphene and T161 as hybrid lubricant additives on 316 ASS surface
Introduction
ASS (Austenitic stainless steel) is widely used in various industrial parts and some specific environment fields such as cylinder liner, the selective laser melting process and the prototype fast breeder reactor (PFBR) due to its great corrosion resistance, excellent oxidation resistance and low cycle fatigue performance [1], [2], [3]. These contact components are often accompanied by sliding wear during operation and maintenance. However, the high friction coefficient and low hardness of ASS compromise their tribological properties, which will also bring challenges to the sheet metal forming and processing in tribologically difficult operations [4]. Usually these components need to be used with lubricants to avoid galling. Compared with coatings, the presence of lubricants can impede wear debris from scratching the substrate and eliminate the heat generated in the friction process [5]. Currently, in order to solve the environmental pollution problem of traditional lubricant additives, researchers have investigated different technologies to explore new additives to replace environmentally harmful additives (ZDDP), including sulfate, sulfur and phosphorus [6], [7].
Graphene shows excellent tribological properties owing to the tightly packed 2D (two-dimensional) laminated structure, high specific surface area and inherent mechanical properties [8], [9]. In the recent past, several reports have demonstrated the potential of 2D graphene as a lubricant additive, in which the characteristics of lamellar structure and surface adherence enable it to easily enter the friction interface, and properties of high strength and toughness as well as excellent thermal properties are conducive to the enhancement of the tribological performance of the lubricants [10], [11]. However, the high price and poor dispersibility of graphene limit the commercial development of graphene lubricants [12], [13]. Interestingly Rasheed et al. [14] reported that very few layers graphene displayed the disadvantages of wrinkling, fracture and poor bending stiffness, while graphene with more layers showed better tribological behaviors. Zheng et al. [15] utilized the molecular dynamics simulations to confirm that the number of graphene folds had a marked impact on the mechanical performance and the strain and compressive strength of folded graphene were much higher than planar graphene. In addition, it has been demonstrated that the graphene with more defects are easier to be dissolved in oil [16]. Consequently, from some certain perspectives, the few-layered graphene with high price may not be the best choice as a lubricant additive.
To solve the problem of graphene dispersibility in oil, researchers tried to add some surfactants or dispersants such as Span 80, but the effect was not satisfactory [17]. Besides, in most studies, the influence of the dispersant itself on the tribological properties was often ignored [18], [19]. Moreover, chemical functionalization is considered as an effective approach. For instance, Mungse et al. [20] used amide bonds to load ODA molecules on acylated rGO to obtain ODA-rGO tablets showing an excellent dispersibility. Kumari et al. [21] reported that the octadecyltriethoxysilane-functionalized h-BNNPs (h-BNNPs-ODTES) remained stable after being placed in pentaerythritol tetraoleate (polyol ester) for 10 days. The main mechanism is that graphene is modified on the edge or surface with polar groups to remove hydroxyl, carboxyl or carbonyl groups, while non-polar group (long alkyl chains) extends into the oil as lipophilic group [20], [21], [22]. The chain length of grafted molecules has a significant impact on dispersibility and the dispersibility of alkylated graphene increases with the increase of the chain length of alkyl grafted. This can be explained by the fact that the longer alkyl chains are easier to fully stretch in the medium to form a steric hindrance layer, which prevents particles from agglomerating and gravitational precipitation [22]. Furthermore, some additives with polar groups and long-chain structures can adsorb or react chemically to form dense molecular layers or thick reactive viscosity layers on polar metal surfaces, thereby reducing friction and wear [23], [24], [25]. For example, some ionic liquids (ILs) can strongly adsorb on the metal surface to form effective protective tribofilms on the sliding surface due to their inherent polarity, and thereby greatly reducing the wear and friction on the steel surface. Investigative results revealed that 1.5% urea-based functionalized imidazolium-organophosphate ionic liquid could significantly reduce the dimension of the wear spot [23]. The addition of 0.8 wt% ricinoleate anion based ionic liquid can effectively reduce the ball wear scar diameter (17–25%) and enhance the load-carrying capacity of base oil [24]. Although diverse different additives sometimes produce antagonistic effects, some ILs and nanoparticles (NPs) exhibit interesting positive synergies as additives of lubricants [26], [27], [28]. For example, N12 ILs and Mo NPs as additives exhibited an excellent anti-wear property [26]. Nasser et al. [27] proved that h-BN and phosphonium ionic liquids as additives for PAO 32 could reduce friction and wear significantly.
In this work, we chose 3D porous graphene and high molecular weight polyisobutylene succinimide (T161) as hybrid additives for PAO 6 base oil. 3D porous graphene is composed of a number of graphene nanosheets, which exhibits superior compressibility and resilience. Its price is also much lower than that of 2D graphene [29], [30], [31]. Excellent electrical conductivity and porous structure are conductive to ion diffusion and electron transport. As an excellent candidate for electrode materials, 3D porous graphene has been extensively investigated in Li-ion batteries (LIBs) and supercapacitors, but its application in tribology remains largely unexplored [29], [30], [31]. Similar in structure to some ILs, high molecular weight polyisobutylene succinimide is a high molecular weight long-chain linear polymer composed of polar end (polyvinyl polyamine block) and non-polar end (polyisobutylene block). Wu et al. [32] have tried to use it as a dispersant of MoS2 nanoparticles in liquid paraffin, but its own contribution to tribological performance still needs to be further investigated.
Herein, we aim to comprehensively and deeply investigate the influence of 3D porous graphene and T161 (High molecular weight polyisobutylene succinimide) as PAO 6 additives on the tribological properties of 316 ASS. Furthermore, the detailed tribological mechanism was also discussed. This work can expand the use of 3D porous graphene in tribology and provide a new opportunity for the production of economic and environmentally friendly fully formulated lubricating oil.
Section snippets
Materials
3D porous graphene (3D PG) was commercially supplied from Lanzhou Institute of chemical physics, Chinese Academy of Sciences. T161 (High molecular weight polyisobutylene succinimide, Molecular weight: 2300) was obtained from Shanghai Minglan Chemical Co., Ltd (China). The base oil used in the tests was PAO 6 was provided by Beijing Hao Runte Trading Co., Ltd. Oleic acid (Molecular weight: 282.45) was obtained from Macklin Biochemical Co., Ltd. (Shanghai, China). According to the producer, the
Characterization
It can be seen from Fig. 1a, b, SEM images reveal that 3D PG shows that the porous 3D framework structure is self-assembled from multiple carbon nanosheets. The appearance shows that most of the flakes are curved and 3D PG displays a honeycomb structure. There are obvious wrinkles on the surface (Fig. S1) and the carbon atom accounts are about 98.5% (Fig. 1c). XPS analysis of 3D PG (Fig. 1d) shows that 3D PG has many oxygen containing functional groups. A C1s peak at 284.8 eV can be attributed
Conclusion
All additives show better AF (anti-friction) and AW (anti-wear) properties than PAO 6 base oil, and 3D PG and T161 display a positively synergistic effect. For graphene and T161, the reduction in wear and the acceptable “sacrificial” coefficient of friction need to be carefully balanced. 3D PG-T161 can form a homogenous and stable dispersion in PAO 6 for several months owing to the inhibition of the agglomeration of 3D PG. During the 60 min test, in comparison with those obtained with pure PAO
CRediT authorship contribution statement
Weicong Gu: Investigation, Writing - original draft. Ke Chu: Conceptualization, Project administration. Zhibin Lu: Writing - review & editing, Project administration. Guangan Zhang: Resources, Supervision. Shunshun Qi: Validation, Data curation.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work was financially supported by National Natural Science Foundation of China (51761024), National Natural Science Foundation of China (11972344) and Sichuan Science and Technology Program (No. 2019YFSY0012).
References (52)
- et al.
Effect of lubricant contaminated with waste ayurvedic oil biodiesel on tribological behavior of cylinder liner-piston ring tribo pair material
Mater Today Proc
(2018) - et al.
Tribology of selective laser melting processed parts: stainless steel 316 L under lubricated conditions
Wear
(2016) - et al.
Effect of temperature on sliding wear of AISI 316 L(N) stainless steel – analysis of measured wear and surface roughness of wear tracks
Mater Des
(2013) - et al.
Frictional mechanisms in mixed lubricated regime in steel sheet metal forming
Wear
(2008) - et al.
Revealing the lubrication mechanism of fluorographene nanosheets enhanced GTL-8 based nanolubricant oil
Tribol Int
(2019) - et al.
In-situ growth of graphene on 90Cu10Ni by electron beam irradiation during EBSD and its anti-corrosion property
Surf Coat Technol
(2020) - et al.
Mono-dispersed Ag/graphene nanocomposite as lubricant additive to reduce friction and wear
Tribol Int
(2020) - et al.
Green hydrothermal synthesis of high quality single and few layers graphene sheets by bread waste as precursor
J Mater Res Technol
(2020) - et al.
Grafting of straight alkyl chain improved the hydrophobicity and tribological performance of graphene oxide in oil as lubricant
J Mol Liq
(2020) - et al.
Heat transfer and tribological performance of graphene nanolubricant in an internal combustion engine
Tribol Int
(2016)
Experimental research on tribological properties of liquid phase exfoliated graphene as an additive in SAE 10W-30 lubricating oil
Tribol Int
Investigation on the lubrication advantages of MoS2 nanosheets compared with ZDDP using block-on-ring tests
Wear
Surface chemistry of graphene and graphene oxide: a versatile route for their dispersion and tribological applications
Adv Colloid Interface Sci
Significantly enhancing lubricity and anti-wear performances of glycerol lubricant with urea-functionalized imidazolium-organophosphate ionic liquid as additive
Tribol Int
Synthesis of ricinoleate anion based ionic liquids and their application as green lubricating oil additives
J Saudi Chem Soc
Understanding the synergistic lubrication effect of 2-mercaptobenzothiazolate based ionic liquids and Mo nanoparticles as hybrid additives
Tribol Int
Phosphonium-organophosphate modified graphene gel towards lubrication applications
Tribol Int
3D porous graphene/NiCo2O4 hybrid film as an advanced electrode for supercapacitors
Appl Surf Sci
3D graphene-based anode materials for Li-ion batteries
Curr Opin Chem Eng
3D hierarchical porous graphene nanosheets as an efficient grease additive to reduce wear and friction under heavy-load conditions
Tribol Int
Characterization of cotton fabric scouring by FT-IR ATR spectroscopy
Carbohydr Polym
Studies on the macromolecular components of nonwood available in Bangladesh
Ind Crop Prod
Electrospinning of linear homopolymers of poly(methyl methacrylate): exploring relationships between fiber formation, viscosity, molecular weight and concentration in a good solvent
Polymer
Effect of liquid crystal molecular orientation controlled by an electric field on friction
Tribol Int
Frictional and wear performance of TiAlN/TiN coated tool against high-strength steel
Ceram Int
XANES investigation of chemical states of nitrogen in polyaniline
Synth Met
Cited by (14)
Graphene nanospheres and their mechanical and tribological responses
2023, Tribology InternationalCobalt phosphate octahydrates nanoflowers as oil-base additives for enhanced tribological performance
2023, Tribology InternationalTribological properties and lubrication mechanism of manganese phosphate trihydrate as lubricant additives
2023, Tribology InternationalCopper phosphate nanosheets as high-performance oil-based nanoadditives: Tribological properties and lubrication mechanism
2023, Tribology InternationalCitation Excerpt :After physical or chemical modifications, graphene was functionalized by oleic acid [15], ionic liquids [16], phosphonium-organophosphate [17], and so on, the good dispersibility in oil was achieved. The COF can be reduced by 80% [18] and wear by 98% [19]. Unfortunately, although the high cost of graphene-based nanomaterials has decreased over the past few years, they are still relatively expensive at engineering scales [20].
Friction-reducing and anti-wear properties of 3D hierarchical porous graphene/multi-walled carbon nanotube in castor oil under severe condition: Experimental investigation and mechanism study
2022, WearCitation Excerpt :Qi et al. also found that the synergistic effect between 3D graphene and 2D hexagonal boron nitride can greatly improve the tribological properties of PAO 4, thus reducing friction and wear of steel/steel contact [34]. In addition, it was proposed by Gu et al. that the synergistic lubrication effect of 3D porous graphene and T161 (high molecular weight polyisobutylene succinimide) in PAO 6 dramatically decreases the friction and wear of 316 ASS surface under specific loads, which is attributed to the formation of a uniform lubricating protective film [35]. Nevertheless, there are still very limited reports on the tribological properties of 3D HPG.