Effect Of Solid Lubricants Research Articles

Sustainable Grease Lubrication Induced by Graphene Oxide and LiFePO4

This study investigates the possibility of modifying lubricating greases by 2D graphene oxide (GO) and lithium iron phosphate (LiFePO4) to enhance their tribological performance. GO's layered structure plays a crucial role in reducing friction by facilitating easy sliding between rubbing surfaces, making it an effective solid lubricant. The impact of these additives on friction reduction, wear resistance, and the tribolayer formation ability is evaluated by ball‐on‐disc tribometry with an emphasis on durability and sustainability. Comparative results reveal that unmodified greases exhibit a high susceptibility to wear, including oxide formation and severe plastic deformation. In contrast, greases with GO show a notable reduction in friction, while the addition of LiFePO4 contributes to the formation of a continuous protective layer that substantially reduces abrasive wear. The combination of GO and LiFePO4 results in a homogeneous, durable tribofilm that effectively protects surfaces against severe wear providing long‐term friction stability. Although lab‐scale LiFePO4 is used, the findings suggest a great potential for extending the useful life of recycled LiFePO4 from lithium‐ion batteries, similar to commercial LiFePO4 thus confirming significant improvements in the grease performance but also highlighting the potential to advance toward more sustainable solutions in industrial applications and electric vehicles.

Enhanced wear resistance and strength synergy in Ti3AlC2 MAX through in-situ synthesis of nano TiB2 heterostructure

The rapid development of science and technology poses the core parts and techniques of industrial tribo-systems facing more stringent situations like high temperature exceeding 600 °C. For this case, solid lubrication materials are required to possess high strength, low friction coefficient and high wear resistance over a wide temperature range. However, achieving such “strong wearable yet lubricated” materials have proven challenging. Here we report a unique reinforced strategy for lubricated Ti3AlC2 MAX ceramic by in-situ synthesis of nano TiB2 heterostructure, which results in a superior high temperature strength and lubrication simultaneously excess other traditional solid-lubrication materials. Such TiB2/Ti3AlC2 composite employs a high level of compressive strength (1120 MPa ∼ 1368 MPa), wear resistance (<10‐5 mm3/(N∙m)) and low friction coefficient (<0.4) at even 800 °C. We show that its unusual properties stem from the introduction of TiB2 nanocrystalline densified and strengthened the Ti3AlC2 matrix thus to ensure the high strength. Meanwhile, the TiB2 also undergoes rapid oxidation along high temperatures friction, resulting in the formation of a continuous and smooth lubricative tribofilm containing solid lubricant B2O3, leading to exceptional solid lubrication effect at high temperature. Our finding provides a potential material portfolio and a new design strategy for high temperature solid-lubricative applications.

Prediction and analysis of wheel flange wear on small curved track considering wheel-rail conformal and lubricated contact

Wheel flange wear on curved tracks is a significant issue that poses a threat to the safety of rail vehicles and leads to increased maintenance costs for railway operators. This study aims to develop a numerical model to predict wheel flange wear on small radius curves. The model integrates an efficient wheel-rail conformal contact model with laboratory-tested wear coefficients. By using virtual penetration and influence coefficients for conformal geometries, the model accurately simulates the conformal contact between the wheel flange and the rail gauge corner. The validity of the wheel flange wear prediction model is confirmed through field tracking testing. Using the proposed model, the effects of track layout parameters and solid lubricants on wheel flange wear are investigated. This study provides theoretical guidance for the operation and maintenance of the wheel-rail system to reduce wear.

Tribological behavior of Ni-based composite coatings produced by cold spray

The current experiment examined the friction and wear characteristics of Ni-based composite coatings developed by cold spray route. In the developed coatings, fixed concentration of MoS2 (10 wt. %) and varying concentrations of Ag (5, 10, and 15 wt. %) were incorporated to evaluate the lubricating potential of reinforcing elements. The specimens were slid in various working regimes of loads (6, 11, 16, &amp; 21 N) and at a fixed sliding speed of 0.3 m/s under room temperature (RT). According to the investigation, all participating composite coatings have revealed a lower coefficient of friction (COF) and wear rate as the testing load increased from 6 to 16 N, beyond which a reverse trend was recorded till 21 N. However, composite coating with 10 wt. % Ag has shown excellent tribological properties in terms of the lowest COF (0.29) as well as wear rate (4.0 × 10−5 mm3/Nm) at 16 N and 0.3 m/s. The superior tribological characteristics of the aforesaid coating have been explained and well connected to the synergistic effect of solid lubricants (Ag and MoS2) as well as the optimal weight percent of Ag in the creation of tribo layer on the wear track.

Synthesis of rice‐granular bimetallic nickel/iron phyllosilicates to simultaneously lubricate and strengthen the epoxy‐based composites

AbstractTo improve the subpar lubricating performance of epoxy resin, this paper presents the preparation of a novel bimetallic phyllosilicate featuring a distinctive rice‐granular morphology, which incorporates nickel and iron metal cations through a facile hydrothermal process. These phyllosilicates were then integrated into the epoxy matrix to form composites. A comprehensive analysis of the target product validates the rationality of the synthesis strategy for the as‐prepared rice‐granular bimetallic nickel/iron phyllosilicate, demonstrating a homogeneous hierarchical structure with numerous tiny nanosheets of nickel/iron phyllosilicate grown in situ on the flat surfaces of the rice‐granular metal–organic frameworks. An adequate addition of nickel/iron phyllosilicates allows for excellent dispersion within the matrix and establishes strongly bonded interfaces, steadily increasing the elastic modulus and hardness. Notably, the average friction coefficients decrease from 0.515 for the pure resin to 0.450 for the composites when the filler content reaches 7%, indicating a significant solid lubrication effect. In contrast, adding just 1% nickel/iron phyllosilicate moderately improves wear resistance, elongation at break, and tensile strength. Furthermore, it was found that as the filler content increased, the weight loss rate was reduced by approximately 43.8%, while the residual char increased by 74.2%, significantly enhancing the thermal stability of epoxy composites at high temperatures. This study offers a promising approach to preparing self‐lubricated epoxy composites with favorable mechanical and thermal properties.Highlights NiFePS was successfully synthesized via a facile two‐step self‐polymerization. Excellent mechanical properties of composites could be achieved with low content of NiFePS. The friction coefficient and wear rate were lowered remarkably. The friction mechanism was solid lubrication.

Effect of solid lubricant additives on solid particle erosion characteristics of rigid and toughened epoxy resins

AbstractSolid lubricants are added to polymers to upgrade their tribological properties, especially in cases where adhesive and abrasive friction are valid. However, there are not enough studies on the effects of solid lubricants on particle erosion. This study investigated the effects on solid particle erosion behavior of three different well known solid lubricants (molybdenum disulfide, polytetrafluoroethylene, and graphite). These solid lubricants were added at three different ratios (5, 10, and 15 wt.%) to the two different type (rigid and toughened) epoxy resins. Garnet abrasive particles (180–400 μm) were blasted to the sample surface under 1.5 bar for 15 s to conduct solid particle erosion tests. The erosive wear mechanisms of neat and solid lubricant‐reinforced epoxy resins were investigated in relation to the epoxy type, solid lubricant type, and solid lubricant reinforcement ratio. Statistical analysis was performed according to response surface methodology to support the experimental results, and ANOVA tables were obtained. The wear and deformations that occurred on the surface after solid particle erosion were examined using a noncontact optical profilometer system and scanning electron microscopy, and a significant relationship was detected between the deformation on the surface and particle erosion. Analysis results showed that the factor causing the greatest erosion rate change was the epoxy resin type. Finally, it has been observed that all solid lubricants reduce the erosive wear resistance, and this resistance decreases as the weight ratio increases.Highlights Investigations were conducted into the erosion behavior of two types of epoxy resins: rigid and toughened. The toughened epoxy resin exhibited greater resistance to erosion. Although it has the same type of content, on average, rigid epoxy worn 2–4 times more than toughened epoxy. The effect of adding polytetrafluoroethylene tended to increase the erosion rate of both rigid and toughened epoxy resin less than that of other solid lubricants. Graphite particles increased the erosion rate of toughened epoxy by 1.5–3 times and that of rigid epoxy by 2–3 times, depending on the value of the reinforcement ratio. MoS2 increased the erosion rate of toughened epoxy by 1.5–3 times and that of rigid epoxy by 2–3 times. Using a noncontact optical profilometer (for investigating surface topography), it was proven that there is a significant relationship between the erosion rate and roughness characteristics. Wear mechanisms were identified by SEM analysis.

Effect of solid lubricant reinforcing on drilling performance of castamide and thermal analysis

AbstractThis study addresses the pressing need for enhancing the machining performance and hole quality of castamide by investigating the effects of solid lubricant addition and drilling parameters. Castamide, a highly crystalline polyamide synthesized via anionic ring‐opening polymerization, offers superior mechanical, physical, and chemical properties compared to conventional polyamide 6. However, its machining process, particularly drilling, remains a critical challenge due to its viscoelastic nature and sensitivity to heat generation. Using experimental investigations, thrust forces, drilling temperatures, hole geometry, and quality parameters are systematically analyzed and discussed. Notably, the study introduces Kestlub, a modified version of castamide with solid lubricant, and evaluates its drilling performance, a previously unexplored area in the literature. The research employs response surface methodology to model experimental data, considering both linear and quadratic effects of drilling parameters. Additionally, the significance of each parameter is assessed using ANOVA tables and Pareto charts, offering valuable insights into optimizing the drilling process for enhanced hole quality in castamide. It found that optimal drilling conditions occur at low rotational speeds and high feed rates, but thermal damage, influenced by factors like thermal conductivity and transition temperature, affects hole geometry and burr formation.Highlights Drilling performances of solid lubricant reinforced castamides were investigated. Drilling temperatures were recorded with a thermal camera and differential scanning calorimeter and thermal gravimetric analyses were performed. Drilling properties were analyzed statistically according to the response surface method. It found that optimal drilling conditions occur at low rotational speeds and high feed rates.

Topology optimization of AISI 4140 steel with surface texture filled by multi-solid lubricants for enhancing tribological properties

Wind power gears will be excessively worn due to lubrication failure during operation. Herein, the tribological properties of rubbing pairs are improved by filling solid lubricants into surface texture. In texture design, three types of topological textures (Circle (C), Hexagon (H) and Circle/Hexagon (CH)) were obtained by cell topology optimization, and then three cases with 20%, 30%, and 40% density were designed for each texture. Next, SnAgCu and TiC were deposited in texture of AISI 4140 steel (AS) to obtain 9 kinds of self-lubricating surfaces. Among them, AS with 30% CH density (AS-CH30) exhibits excellent mechanical and tribological properties. Compared with AS-C and AS-H, the maximum equivalent stress of AS-CH was decreased by 10.86% and 5.37%, respectively. Friction coefficient and wear rate of AS-CH30 were 79.68% and 78% lower than those of AS. The excellent tribological performances of AS-CH30 can be attributed to the synergistic effect of topological surface and solid lubricants. Topological surface can not only reduce fluctuation of equivalent stress, but also promote the stored lubricants to be easily transferred at the contact interface to form a 200 nm lubricating film containing solid lubricants (mainly), oxides and wear debris.

Understanding the effect of solid lubricants on scratch behavior in epoxy resins: An experimental and statistical approach

AbstractEpoxy resins inherently have low resistance to scratching. To increase the scratch resistance of epoxy resins, reinforcing solid lubricants into the resin is an option. For this purpose, in this study, polytetrafluoroethylene (PTFE) and graphite were reinforced in two different epoxy resins (rigid and toughened) at different reinforcement ratios (5, 10, and 15 wt%). The effects of solid lubricant reinforcement on the scratch behavior of rigid and toughened epoxy resins were examined both experimentally and statistically. Scratch tests were performed throughout a distance of 10 mm using a test apparatus under a load of 15 N and a scratch speed of 30 mm/min. Following the scratch tests, the COF (Coefficient of Friction) values, scratch hardness, scratch width, and depth of all samples were determined and compared to neat epoxy for each resin. In general, it has been determined that solid lubricant reinforcement at higher reinforcement ratios has a positive effect on the COF value (15 wt%). In the case of 15 wt% graphite reinforced rigid and toughened epoxy, a decrease of 15.90% and 17.77%, respectively, was obtained in the COF value compared to the neat epoxy. After the scratch tests, statistical analysis was performed according to RSM to support the experimental results, and ANOVA tables were obtained.Highlights Epoxy adhesives exhibit low scratch resistance. Examining the impact of PTFE and graphite reinforcement on scratch behavior. Two types of epoxy and varied reinforcement ratios (5, 10, and 15 wt%) were studied. Solid lubricant reinforcement to epoxy positively affected scratch behavior.

Comparison of conventional hydrothermal and microwave‐assisted synthesized g‐C3N4/MoS2 nanocomposite coated steel substrate by tribological measurement

AbstractMolybdenum disulfide is an effective solid lubricant, but it suffers from oxidation and moisture absorption issues, resulting in insufficient wear resistance and a shortened lifespan. This study introduces an innovative approach, integrating graphitic carbon nitride with molybdenum disulfide via advanced microwave‐assisted synthesis, offering precise control over synthesis parameters. The research assesses the tribological performance, comparing it with conventional hydrothermal synthesis. The study extensively investigates the morphology, microstructure, and tribology of a g‐C3N4/MoS2 nanocomposite created through novel microwave (g‐C3N4/MoS2‐MW) and hydrothermal techniques (g‐C3N4/MoS2‐HT). MoS2 exhibits a flower‐like structure, while graphitic carbon nitride has a layered structure, as confirmed by elemental analysis via energy‐dispersive X‐ray spectroscopy. X‐ray diffraction identifies g‐C3N4 peaks at 13.0° (100) and 27.5° (002) and hexagonal MoS2 peaks at 14° (002), 32.7° (100), 35.8° (102), and 58.3° (110). The Fourier‐transform infrared spectrum reveals peaks at 1237.4 and 808 cm−1 (aromatic and triazine ring breathing modes in g‐C3N4), 1407.1 and 1638.9 cm−1 (C=N and C−C heterocyclic structures), and 3432 cm−1 (vibrations due to −NH and −OH). The coefficients of friction for microwave‐assisted and traditional hydrothermal synthesized nanocomposites are 0.22 and 0.34, respectively. The wear depths are 98 microns and 141 microns, with a wear scar diameter of 2.87 mm for g‐C3N4/MoS2‐MW and 3.45 mm for g‐C3N4/MoS2‐HT, indicating superior lubrication with the microwave‐assisted coating.

Tribological behavior under 1200°C elevated temperature of spark plasma sintered h-BN bulk

h-BN with a layered crystal structure is one type of effective solid lubricants, especially at elevated temperatures. In present work, h-BN with relative density of about 91% was prepared by SPS technology, and its tribological behavior under 1200 °C was investigated. The results exhibited that the friction coefficient of h-BN was relatively stable when paired with Si3N4, which stayed at the range of 0.215–0.305. Low friction coefficient under 1200 °C was mainly thought to be the effect of weaker interlaminar binding of h-BN and easier slip of h-BN plates under higher temperature. Because of low hardness and fracture toughness, wear mechanism of h-BN was mainly brittle fracture, while coexistence of B2O3 and Al5BO9 was beneficial for reducing wear rate.

The effect of solid lubricants in the brake friction composite on brake emissions: A case study with graphite, Sb2S3, and MoS2

Particulate matter produced during brake application was investigated, focusing on the effect of the solid lubricants in the brake friction composite, such as graphite, antimony trisulfide, and molybdenum disulfide. Results showed that the brake emission was significantly affected by the solid lubricant type and braking temperatures. Antimony trisulfide caused high brake emissions at moderate temperatures, whereas graphite produced high emissions at elevated temperatures. The brake emission at moderate temperatures was affected by the aggressiveness of the composites and the presence of friction films on the gray iron disc surface. In contrast, the brake emissions at elevated temperatures were determined by the thermal decomposition of the composite and the oxidation of solid lubricants.

Evolution of different third bodies and their influences on the tribological properties of C/C-SiC composites

Friction film has an important influence on the tribological properties of C/C-SiC composites, which is closely related to its composition. In this study, exogenous third bodies in the form of powders of graphite, SiC, SiO2 and a mix of graphite, SiC, and SiO2 powders were added to the friction surface of the C/C-SiC composites under a constant speed. By comparing the change in the coefficient of friction (COF) and the wear rate of the C/C-SiC composites before and after addition of exogenous third bodies, the influence of each component on the tribological properties of the C/C-SiC composites and its mechanism were proposed. The graphite third body had a solid lubrication effect, with the average COF bellowing 0.344 and a 24% reduction in wear rate after addition. With the addition of SiC and SiO2 third body, the average COF was greater than 0.550 and 0.441, and the wear rate increased by 128.4% and 25.1%, respectively. SiO2 with a stronger pinning effect, promoted the formation of friction film and ultimately resulted in a smaller increase in average COF and wear rate. With the addition of the multi-component third bodies, the first platform containing SiO2 and SiC was formed, which resulted in a reduction in sharpness and being prone to refinement. Meanwhile, the large first platform accelerates the formation of friction film. Furthermore, while the first platform exceeded to the bearing capacity, SiC and SiO2 started to decompose, and redistributed in the friction film, which cause the instantaneous COF tended to stable with a low wear rate.

Microstructural and tribological properties of TiO2/Ag multilayer coatings using magnetron sputtering technique for potential applications in non-permanent implants

The development of ideal surfaces for metal implants and osseous stabilization devices requires consideration of various phenomena. These include the formation of bacterial biofilms on the surface, which can lead to infections or rejection of the device. Additionally, the overgrowth of bone material around these devices can create a barrier to their removal once their function has been fulfilled. Due to this, the development of multilayer antibacterial coatings of TiO2/Ag on Ti6Al4V substrates was studied for potential use in non-permanent implants. Magnetron Sputtering technique, which provides significant control over the microstructural features was used to deposit 10 and 15 TiO2/Ag bilayers, resulting in coatings with a uniform and packed structure. Additionally, TiO2 monolayer was used as a comparative sample. Consequently, the properties of the developed systems were characterized using scanning electron microscopy/energy dispersive spectroscopy, Raman spectroscopy, X-ray diffraction, tribologic assays and surface properties such as rugosity and wettability. Experimental results confirm the presence of crystalline anatase in all systems and an increase both in thickness and roughness as the bilayer number increases compared to TiO2 monolayer coatings. Multilayer coatings evince decreased wettability and crystallinity with higher bilayer counts compared to the highly hydrophobic nature of Ti6Al4V substrates (>90°). Both systems, 10 and 15 multilayer coatings present a thickness of approximately 730 nm and improved hydrophilicity with contact angles of 68.5° and 55.2° respectively, while the TiO2 monolayer grew around 1300 nm and had a contact angle of 86.3° Finally, the tribological properties improve as the silver content on the surface increases as the noble metal tends to accumulate in nanoparticles on the outermost layers of the multilayer systems, exhibiting its solid lubricating effect, however, the wear rate increases for 15TiO2-Ag sample, as more Ag migrates, altering the coating microstructure.

Tribological and radiation shielding response of novel titanium-boron nitride coatings for lunar structural components

Aluminum (Al) and titanium (Ti) lightweight alloys play a crucial role in space systems due to their exceptional strength-to-weight ratio. However, their premature failure in the presence of lunar regolith and their lack of neutron shielding ability are significant challenges. To address these issues, we have developed air and vacuum plasma-sprayed hBN (hexagonal Boron Nitride) -reinforced titanium coatings with 2 and 10 vol% of hBN. Tribological studies conducted with JSC-1 A lunar regolith simulant revealed a 90 % reduction in wear volume for the Ti/2 vol% hBN coatings compared to conventional materials due to the synergistic action of harder secondary phases and solid lubrication effect of hBN. Additionally, a 27 % enhancement in radiation shielding is obtained based on the mass absorption coefficient (radiation absorbed per sample density and thickness) for VPS Ti/2 vol% hBN coatings.

Bionic sweat high temperature self-lubricating coating based on ceramic precursor polysilazanes

Bionic sweat high temperature self-lubricating coating were prepared using ceramic precursor polysilazane and MoS2, Ag and BaF2 as fillers through high temperature chemical reaction to produce ceramic adhesive and molybdate solid lubricants. And the addition of active ZrB2 filler converted into ZrO2 and B2O3 through high temperature oxidation reaction not noly solved the cracking issues caused by the pyrolysis of polysilazane, but also enhances the tribology property due to the excellent fluidity and lubricity of the molten B2O3 through phase transition at high temperature through bionic sweat. Furthermore, the coating treated at 700 °C has the best lubrication performance at 500 °C, 2 N and 100 rpm that the friction coefficient was 0.223 and the wear rate was 1.53 × 10−4 mm3/N·m, respectively. Synergistic effect of solid lubricants and molten B2O3 leads to excellent lubrication property.

Experimental study on the effect of solid lubricants on wheel rail contact wear and surface hardness evolution

PurposeThe CL60 steel wheels of subway vehicles operating on specific lines require frequent refurbishment due to rapid wear and tear. Considering this issue, MoS2-based and graphite-based solid lubricants are used to reduce the wear rate of subway wheels and extend their service life.Design/methodology/approachUnder laboratory conditions, the effect of MoS2-based and graphite-based solid lubricants on the friction and wear performance of subway wheels and rails was evaluated using a modified GPM-60 wear testing machine.FindingsUnder laboratory conditions, MoS2-based solid lubricants have the best effect in reducing wheel/rail wear, compared to the control group without lubrication, at 2 × 105 revolutions, the total wheel-rail wear decreased by 95.07%. However, when three types of solid lubricants are used separately, the hardness evolution of the wheel-rail contact surface exhibits different characteristics.Practical implicationsThe research results provide important support for improving the lifespan of wheel and rail, extending the service cycle of wheel and rail, reducing the operating costs of subway systems, improving the safety of subway systems and providing wear reduction maintenance for other high wear mechanical components.Originality/valueThe experiment was conducted through the design and modification of a GPM-60 testing machine for wear testing. The experiment simulated the wheel-rail contact situation under actual subway operation and evaluated the effects of three different solid lubricants, MoS2-based and graphite-based, on the wear performance and surface hardening evolution of subway wheel-rail.

Tribological properties of high-speed steel surface with texture and vertical fibers

Inadequate lubrication of the two touching surfaces during friction can lead to severe wear, especially in metal cutting. Therefore, a surface with synergistic anti-friction effect of texture and solid lubricant was proposed to improve lubrication. A mesh texture with excellent wettability was prepared on the high-speed steel (HSS) surface by laser, and then nylon fibers were vertically implanted into the grooves of the texture using the electrostatic flocking technology. The friction and wear state of different surfaces (smooth, textured, flocking) under dry/oil-lubricated were studied by a linear reciprocating wear tester. The coefficient of friction (COF) under different working conditions was used to analyze the anti-friction properties, and the wear rate was used to evaluate the wear resistance of the surface. The results showed that the tribological properties of flocking surfaces were better than those of the other two surfaces. This is because the addition of nylon fibers eases shear at the edges of the texture. The broken fibers form a solid lubricating film on the specimen surface, which prevents the surface from being scratched by debris. In addition, it is found that COF decreases with increasing load. Finally, the rapid wettability of the oil droplets on the flocking surface shows the great potential of the surface for lubrication and anti-friction.

Nickel metal matrix composites reinforced with solid lubricants: A comprehensive review

Nickel metal matrix composites are suitable for aerospace and military applications due to their superior mechanical and tribological properties. The incorporation of reinforcing components in the nickel metal matrix composites significantly improves the specific strength, microhardness, wear resistance, frictional behavior, creep, and fatigue characteristics, as well as provides exceptional surface quality in comparison to typical engineering materials. The current study attempted to explore a review on nickel composites reinforced with various solid lubricants, along with their pros and cons. The study focuses on the issues like interfacial transition, agglomerating activity, and non-uniform particle dispersion. Several studies have been conducted to highlight the effect of solid lubricants on the microstructure, mechanical and tribological characteristics such as tensile strength, yield strength, ductility, hardness, friction, wear, and fatigue. In this review, the principal applications of various nickel matrix composites are also thoroughly examined.

Degradation analysis of tribologically loaded carbon nanotubes and carbon onions

Coating laser-patterned stainless-steel surfaces with carbon nanotubes (CNT) or carbon onions (CO) forms a tribological system that provides effective solid lubrication. Lubricant retention represents the fundamental mechanism of this system, as storing the particles inside the pattern prevents lubricant depletion in the contact area. In previous works, we used direct laser interference patterning to create line patterns with three different structural depths on AISI 304 stainless-steel platelets. Electrophoretic deposition subsequently coated the patterned surfaces with either CNTs or COs. Ball-on-disc friction tests were conducted to study the effect of structural depth on the solid lubricity of as-described surfaces. The results demonstrated that the shallower the textures, the lower the coefficient of friction, regardless of the applied particle type. This follow-up study examines the carbon nanoparticles’ structural degradation after friction testing on substrates patterned with different structural depths (0.24, 0.36, and 0.77 µm). Raman characterization shows severe degradation of both particle types and is used to classify their degradation state within Ferrari’s three-stage amorphization model. It was further shown that improving CNT lubricity translates into increasing particle defectivity. This is confirmed by electron microscopy, which shows decreasing crystalline domains. Compared to CNTs, CO-derived tribofilms show even more substantial structural degradation.