Tribo-mechanical Properties Research Articles

Microstructure and tribo-mechanical properties of APS-sprayed NiAl/Cr2AlC composite coatings with various additions of self-made Cr2AlC

The microstructures, tribo-mechanical properties of the fabricated NiAl/Cr2AlC composite coatings with various additions of self-made Cr2AlC were comparatively investigated. The results indicated that appropriate addition (10 wt%) of Cr2AlC could improve the microstructure, hardness, bending strength and tribological performance of the coatings. However, excessive addition of Cr2AlC led to the loose structure, decreased bending strength and adhesive strength of the coatings. The added Cr2AlC played a critical role of lubrication and wear resistance at low and medium temperatures due to its layered structure, leading to the low COFs and wear rates. At higher temperatures, the Cr2AlC accompanied with the generated oxides such as Al2O3, Cr2O3 and NiO played a critical role of antifriction and anti-wear, resulting in the significant reduced COFs and wear rates. The NiAl/Cr2AlC composite coating with the Cr2AlC addition of 10 wt% exhibited excellent tribological performance from room temperature to 800 °C.

Surface modification of coatings based on Ni-Cr-Al by pulsed plasma treatment

<abstract> <p>To protect materials from abrasion-corrosion, various thermal spraying methods can be used to apply coatings, such as gas-flame powder spraying, plasma spraying, high velocity oxygen-fuel spraying and detonation cannon. Thermal spraying is one of the most effective methods of protecting the material from wear and corrosion, thereby increasing the service life of the material used. We present the surface modification of coatings based on Ni-Cr-Al by a pulsed plasma treatment using a plasma generator. The coatings were obtained by detonation spraying followed by pulsed plasma treatment. The changes to the structural properties of the coatings under the influence of plasma flow were studied using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The mechanical and tribological properties were analyzed by surface roughness characterization, microhardness testing and tribological tests for a comprehensive analysis of changes in the characteristics of the Ni-Cr-Al coatings following pulsed plasma treatment. It was found that modification of the coating by pulsed plasma treatment causes an increase in the microhardness of the surface layer, as well as a reduction in the surface roughness and friction coefficient. According to the results of X-ray phase analysis, these improvements in the mechanical and tribomechanical properties of the obtained surfaces is associated with an increase in the content of CrNi<sub>3</sub>, NiAl and NiCr phases in the coatings.</p> </abstract>

Synthesis and Thermal Adsorption Characteristics of Silver-Based Hybrid Nanocomposites for Automotive Friction Material Application

Advances in friction materials are imposed on developing multiceramic reinforced hybrid nanocomposites with superior tribomechanical properties. The silver-based matrix metals are gained significance in various applications like bearing, ratchet, and electrical contacts due to their high frictional resistance and good thermal and chemical stability compared to traditional metals. The present research is to develop silver-based hybrid nanocomposites containing alumina (Al2O3) and silicon carbide (SiC) nanoparticles of 50 nm mixing with the ratio of 0 wt% Al2O3/0 wt% SiC, 5 wt% Al2O3/0 wt% SiC, and 5 wt% Al2O3/5 wt% SiC via the semisolid vacuum stir-cast technique. The vacuum technology minimizes casting defects and increases composite properties. The casted composite samples are subjected to study the effect of reinforcement on thermal adsorption, conductivity, diffusivity, and frictional resistance. The composite containing 5 wt% Al2O3np/5 wt% SiCnp is to find optimum thermal and frictional behaviour. The thermal adsorption and frictional resistance are increased by 30% and 27% compared to unreinforced cast silver. The Ag/5 wt% Al2O3np/5 wt% SiCnp hybrid nanocomposite is recommended for automotive friction-bearing applications.

Ultralight Functionally Graded Hybrid Nanocomposites Based on Yttrium and Silica-Reinforced Mg10Li5Al Alloy: Thermal and Tribomechanical Properties.

Despite the amazing properties of lightweight Mg10Li5Al alloy, its use in industrial applications is highly limited due to its low mechanical properties, wear resistance, and coefficient of thermal expansion (CTE). In this context, this work aimed to improve the above properties without sacrificing the important benefit of this alloy being lightweight. Therefore, function grade composites (FGCs) were prepared based on the Mg10Li5Al alloy reinforced by yttrium (Y) and silica fume using the powder metallurgy technique. Then, the nanocomposite's microstructure, mechanical properties, artificial aging, wear resistance, and thermal expansion were examined. The results indicated that the precipitation (MgAlLi2), softening (AlLi2), and Mg24Y5 phases were formed in high-reinforced samples during high-energy milling. Furthermore, the addition of reinforcements accelerated the decomposition from the MgAlLi2 phase to the Al-Li phase (softening point). For the layer containing the highest reinforcement content, microhardness, strength, and Young's modulus improved up to 40, 22.8, and 41%, respectively, due to the combined effect of the high strength of silica fume and the dispersion strengthening Mg24Y5 phase. Meanwhile, the same sample exhibited a remarkable improvement in wear rate and the CTE value to about 43 and 16.5%, respectively, compared to the non-reinforced alloy.

Effect of nano-phased bismuth–tin alloy surface coating on tribo-mechanical properties of basalt fiber reinforced composites

A novel method for coating basalt fiber with a eutectic bismuth–tin (Bi–Sn) mixture was developed. Bi-Sn nanoparticles were synthesized using a sol-gel process and deposited on basalt fiber by chemical vapor deposition, with the aim of evaluating the tribo-mechanical properties of the final epoxy-composite material. X-ray diffraction showed that the synthesized Bi–Sn alloy was highly polycrystalline with equal distribution of tetragonal and orthorhombic Bi–Sn polymorph phases with crystallite sizes between 17 and 55 nm. High-resolution electron microscopy revealed that the sample possesses highly fused, flake-stacked planar layers, with 50 nm-thick flakes of variable length. Elemental analysis determined that the alloy contains 57% Bi (at.wt%), and Raman spectroscopy confirmed the characteristic Bi–Sn fingerprint peaks of 148, 201, and 397 cm−1. Thermal analysis of the composites showed good thermal stability with only 4% mass loss at 700 °C. Furthermore, an increase in the Bi–Sn loading enhanced the tribo-tensile properties. It was found that at a Bi-Sn gravimetric loading of 0.2 g the composite yielded the highest ultimate tensile strength of 303 MPa compared to the reference (154 MPa), even as the Young's moduli showed a decrease in elasticity by up to 24.99%. Moreover, the tribology results showed a good friction coefficient (0.5), with a negligible wear rate (4.53 × 10−8 mm3/Nm) and relatively low wear volume (0.118 mm3). Thus, the proposed method resulted in alloy composites with improved tribo-mechanical properties, and has potential applicability in the development of lead-free solders.

Natural Computing-Based Designing of Hybrid UHMWPE Composites for Orthopedic Implants

The current study deals with the design of ultra-high molecular weight polyethylene (UHMWPE) composites by integrating various micro and nanoparticles as reinforcements for enhanced performance of acetabular cups in hip prostheses. For the design, a data-driven design approach was implemented, exploiting natural computing techniques such as Artificial Neural Network (ANN) and Genetic Algorithm (GA). Experimental data related to UHMWPE reinforced with carbon nanotube, graphene, carbon fiber, and hydroxyapatite were gathered from the published works of previous researchers. To study the relationship between the volume fraction and the morphology of the particles with the tribological and mechanical properties of the composites, ANN modeling and sensitivity analyses were used. Optimization of the properties was done with the developed ANN models as objective functions in order to find the optimal combinations of reinforcements, which helps to achieve enhanced tribo-mechanical properties of the composites. This natural computing approach of designing the UHMWPE composites paved a way for experimentation.

Effect of film thickness on the structural and tribo-mechanical properties of reactive sputtered molybdenum nitride thin films

The current study aims to examine the impact of nitrogen content and film thickness on the structural and tribo-mechanical characteristics of reactive sputtered MoN thin films. Molybdenum nitride thin films with thicknesses ranging from 0.2 to 1.25 m have been applied to steel and silicon substrates for this purpose, with various amounts of controlled atmosphere (Ar+N2). Then, the films are characterized using XRD (X-ray diffraction), EDX (energy dispersive X-ray analysis), SEM (scanning electron microscopy), FTIR (Fourier-transform infrared spectroscopy), and nanoindentation. The residual stress was measured using the Stoney formula. Results show that a high compressive residual stress of -5.7 GPa is present in the film with a 0.3 μm thickness and gradually decreases with increasing film thickness. Above 1 µm of film thickness, there is no change in the density of the MoN films. Also, the coating hardness and Young’s modulus vary between 9.5 and 35 GPa, and 266 and 320 GPa, respectively, depending on nitrogen content and film thickness. Lastly, the friction of the MoN thin films is estimated to be around 0.55, which proves that the oxide is being slowly removed.

MXene-aromatic thermosetting copolyester nanocomposite as an extremely wear-resistant biocompatible implant material for osteoarthritis applications

Osteoarthritis disorder ranks amongst the most common disabling chronic diseases in young and older adults worldwide. It is linked to degenerative joint diseases and frequently occurs with pain in the knee, hand, hip, and feet. This progression breaks down the cartilage and underlying bones over time and causes motion disability. Artificial bone implantation is a standard therapy to treat patients with severe osteoarthritis injuries. However, commonly-used polymeric implant materials such as polyethylene, poly(aryl ether ether ketone) (PEEK), and polymethyl methacrylate are reported to possess weak tribological properties. In this regard, the wear debris contributes to the progress of periprosthetic osteolysis, and replacement of implant might be required at later stages. This study reports the development of an extremely high wear-resistant composite including aromatic thermosetting copolyester (ATSP) matrix and titanium carbide (Ti3C2Tx) MXene nanosheets reinforcement. The tribomechanical properties of the ATSP-MXene composite were tuned by optimizing the MXene content. The ATSP-MXene is highly biocompatible with mesenchymal stem cells and possesses excellent compressive strength, hardness, and wear resistance in synovial fluid over conventional polyethylene material. Overall, the designed ATSP-MXene shows promising properties of an implant material that paves its way for future applications in medicine.

Influence of varying nitrogen content on the structural, tribomechanical properties and machining performance of CrNx-WS2 nanocomposite coatings

This study reports the reactive co-sputtering of CrN and WS2 in order to develop CrNx-WS2 solid lubricant nanocomposites. The nitrogen flow rate during the deposition process was varied within a range of 10–50 sccm and its influence on crystal structure, composition, surface morphology, mechanical properties and tribological properties were systematically analysed. Grazing Incidence X-Ray Diffraction (GIXRD) studies revealed a change in the preferred orientation (200) with varying nitrogen flow rates along with significant broadening of peaks to demonstrate the formation of CrNx-WS2 nanocomposite thin films. The maximum nanohardness of the CrNx-WS2 nanocomposites was observed to be 29 GPa. Scratch test studies revealed a highest critical load of 222 GPa for CrNx-WS2 films which is three times more than that of the pristine WS2. The frictional coefficient of the CrNx-WS2 nanocomposite thin films was observed to be 0.16 while pristine WS2 had a frictional coefficient of 0.08. The wear studies of CrNx-WS2 nanocomposite thin films showed an improvement by 2.9 times when compared to pristine WS2 and 2.5 times when compared to pristine CrN. Machining studies carried out using the CrNx-WS2 coated tools showed reduction in cutting force by 8–12 % when compared to commercial tools. Tool life studies revealed an increase in tool life by 19 % for CrNx-WS2 coated tools in comparison to commercial tools owing to the reduction in tool-chip contact length.

Surface Mo or Ni-Enrichment Applied to Granulated Self-Lubricating Composites: Microstructural and Tribological Evaluation

Sintered self-lubricating components may present inappropriate mechanical properties despite their excellent tribological properties. In general, alloying elements are used to improve these properties, but with a cost increase. As an alternative, surface enrichment (or surface alloying) with alloying elements may be applied. This study developed and characterized sintered composite materials surface-enriched with nickel or molybdenum. The results showed that the surface enrichment process is useful for increasing the tribomechanical properties. The Mo-enriched samples presented superior tribological results. Compared with the reference samples (not enriched), the Mo-enriched specimens showed an increase of 4,954% in scuffing resistance, lower friction coefficient (0.09), and reduced wear rate (68% and 96% lower for the specimen and the counter body). These results were mainly attributed to microstructural modification.

Deposition of carbonitride titanium coatings by magnetron sputtering and its effect on tribo-mechanical properties

Metal parts in machinery often fail as a result of damage caused by wear and tear, resulting in the loss of functionality of the products. Thin film solid nitride coatings are used to improve the wear resistance and service life of parts and are considered to be effective. The article presents a brief overview of modern literature in the field of obtaining wear resistant coatings of titanium carbonitride by using magnetron sputtering. The review presents a detailed assessment of the scientific results obtained depending on the deposition parameters and the conditions for obtaining coatings. The results of the coefficient of friction, wear rate of the coating and counterbody, nanohardness and adhesion force of coatings obtained by magnetron sputtering and its modifications are shown. The influence of alloying elements on the mechanical and tribological properties of titanium carbonitride coatings is considered. Recent advances in the production of titanium carbonitride coatings with improved wear characteristics are discussed.

Physical properties evolution of β-tricalcium phosphate/hydroxyapatite heterostructures in relation to the bilayer number

Tribo-mechanical properties for the heterostructures based on β-tricalcium phosphate (β- TCP) (Ca3(PO4)2) and hydroxyapatite (HA) (Ca5(PO4)3(OH)) as a function of the bilayers number (n = 1, 10, 30 and 50) were deposited on metallic AISI 302 steel substrates. In this sense, the β-TCP layer was deposited on the substrate surface, and the HA layer was deposited on the multilayer system surface (Steel [β-TCP/HA]n).The results obtained shows a reduction of 46% in roughness and a 16% in grain size when comparing the coating with 50 bilayers with the coating with 1 bilayer. Subsequently, the coating with 50 bilayers showed an increase of 108% in the hardness compared to the coating with 1 bilayer and the tribological properties showed a reduction in the friction coefficient of 32% of the coating with 50 bilayers with the coating with 1 bilayer. The results obtained in this research evidenced that the coating with 50 bilayers presented the best set of surfaces, mechanical and tribological properties. In this sense, this heterostructure coating deposited with n = 50 bilayers is the best option to be incorporated on biomedical devices, in order to confer higher wear resistance in the biomedical equipments.

Tribomechanical and microstructural properties of cathodic arc-deposited ternary nitride coatings

Sintered carbides are promising materials for surfaces that are exposed to extreme wear. Owing to their high service load, ceramic-based thin films are coated on carbides using different techniques. In this study, non-toxic and cobalt-free powder metallurgy-sintered carbide samples were coated with TiN, TiAlN, CrAlN, and TiSiN ceramic-based thin film coatings by cathodic arc physical vapor deposition. The microstructure (phase formation, coating thickness, surface roughness, and topography), mechanical properties (hardness, modulus of elasticity, and plasticity indices), and tribological properties (nanoscratch and wear behavior) of the thin film coatings were investigated. No cracks or defects were detected in these layers. The ceramic-based ternary nitride thin film coatings exhibited better mechanical performance than the TiN coating. The TiN thin film coating had the highest average surface roughness, which deteriorated its tribological performance. The ternary nitride thin film coatings exhibited high toughness, while the TiN thin film coating exhibited brittle behavior under applied loads when subjected to nanoscratch tests. The wear resistance of the ternary nitride coatings increased by nearly 9–17 times as compared to that of the TiN coating and substrate. Among all the samples investigated, the substrate showed the highest coefficient of friction (COF), while the TiSiN coating exhibited the lowest COF. The TiSiN thin film coating showed improved mechanical and tribological properties as compared to other binary and ternary nitride thin film coatings.

Tribo-mechanical measurements and in vivo performance of zirconia-containing biphasic calcium phosphate material implanted in a rat model for bone replacement applications

The present study aimed to optimize the mechanical and tribological performance of biphasic calcium phosphate (BCP) without sacrificing its excellent bioactivity and bioresorbability to be suitable for bone replacement applications. Zirconia (ZrO2) was added to BCP in various proportions to achieve this goal. Then resulting nanocomposites powders were sintered and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Tri-bological measurements were determined for all samples prepared at different loads along with mechanical properties in terms of microhardness, compressive strength and elastic moduli group. Since the bioactivity of BCP could not be accurately evaluated in vitro, a selected nanocomposite was implanted in rats for 1, 2, 3 and 4 weeks. The obtained results showed that ZrO2 played a strong role in improving the tribo-mechanical properties of the prepared nanocomposites. It also reduced the particle sizes of the prepared powders from 64.5 to 43.4 nm. The implanted sample was completely covered and surrounded by fibrous connective tissue after two weeks, indicating the excellent bioactivity of this specimen. Based on these results, the prepared nanocomposites are suitable for bone replacement applications.

Effect of processing parameters on Tribo-mechanical properties of developed Nano-Composite Coating of h-BN & B4C on Ti6Al4V Substrate by Laser Surface Alloying

ABSTRACT This work deals with the development of hard coating of h-BN + B4C mixed powder on the Ti6Al4V surface through laser cladding under different processing conditions of laser power and scanning speed. A hard multicomponent nanocomposite coating has constituent phases of TiB2-TiC-TiCN-h-BN-B4C-C3N4-B13C2. This composite coating has been synthesised by laser cladding of pre-placed h-BN and B4C mixed powders on the Ti6Al4V substrate. In this investigation, the average thickness of the coating has been taken up to 50 µm with a maximum microhardness of 2814 HV0.05. The developed coatings have been characterised by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and hardness and wear test, and a correlation is established between the microstructure and the hardness value. TEM analysis reveals the formation of an intricate nanostructure in the coatings during laser cladding. The results indicate the significant improvement in the hardness and tribological characteristics of the coated Ti6Al4V substrate. Improvement in the hardness and wear resistance is attributed to the presence of nanocrystalline phases of C3N4, B13C2 and TiCN, which are formed due to the addition of titanium boride and titanium carbide elements. The present investigation provides valuable insights into the development of nanocomposite coating on the metal surfaces.

PVA-Based Hydrogels Loaded with Diclofenac for Cartilage Replacement.

Polyvinyl alcohol (PVA) hydrogels have been widely studied for cartilage replacement due to their biocompatibility, chemical stability, and ability to be modified such that they approximate natural tissue behavior. Additionally, they may also be used with advantages as local drug delivery systems. However, their properties are not yet the most adequate for such applications. This work aimed to develop new PVA-based hydrogels for this purpose, displaying improved tribomechanical properties with the ability to control the release of diclofenac (DFN). Four types of PVA-based hydrogels were prepared via freeze-thawing: PVA, PVA/PAA (by polyacrylic acid (PAA) addition), PVA/PAA+PEG (by polyethylene glycol (PEG) immersion), and PVA/PAA+PEG+A (by annealing). Their morphology, water uptake, mechanical and rheological properties, wettability, friction coefficient, and drug release behavior were accessed. The irritability of the best-performing material was investigated. The results showed that the PAA addition increased the swelling and drug release amount. PEG immersion led to a more compact structure and significantly improved the material’s tribomechanical performance. The annealing treatment led to the material with the most suitable properties: besides presenting a low friction coefficient, it further enhanced the mechanical properties and ensured a controlled DFN release for at least 3 days. Moreover, it did not reveal irritability potential for biological tissues.

Bioactive Bilayer Glass Coating on Porous Titanium Substrates with Enhanced Biofunctional and Tribomechanical Behavior

The use of porous titanium samples fabricated by space-holder powder metallurgy with bioactive coatings has already been reported to prevent resorption of the bone surrounding the implant and improve osseointegration, respectively. However, the presence of pores as well as the poor adherence and the brittle behavior inherent to glassy coatings affect the service behavior of implants fabricated from these samples. Therefore, they need to be optimized. In this work, 50 vol.% of porosity titanium substrates were manufactured with different pore range size (100–200 and 355–500 µm) spacer particles and coated with a bilayer of bioactive glasses (45S5/1393). The effect of the pores on the tribomechanical properties and infiltration of the bioactive glass 1393 along with the bioactivity of the bioactive glass 45S5 were evaluated by instrumented micro-indentation and scratch tests and the formation of hydroxyapatite in simulated body fluid. The results obtained were very promising as potential implants for the replacement of small tumors in cortical bone tissues, mainly due to the smaller pores that present an improved biomechanical and biofunctional balance.

Investigation of Tribo-Mechanical Properties of Polyamide 6 Nano-Biocomposite: Novel Approach Prediction of Fiber Orientation with OMMT

Investigation of Tribo-Mechanical Properties of Polyamide 6 Nano-Biocomposite: Novel Approach Prediction of Fiber Orientation with OMMT

Silicon- and tungsten-containing hydrogen-free and hydrogenated amorphous carbon films for friction-reducing applications

For tribological applications, adding Si or W to hydrogen-free a-C or hydrogenated a-C:H is highly beneficial to tailor the film properties. Hence, a direct comparison between Si- and W-containing a-C and a-C:H considerably enhances the understanding of both the interaction between Si or W and the hydrogenation state as well as its effect on the structure and tribo-mechanical properties of these films. Therefore, non-modified a-C(:H), Si-containing a-C(:H):Si, and W-containing a-C(:H):W films were systematically grown in a mid-frequency magnetron sputtering process.The formation of W-based nanocrystallites within a-C(:H):W is identified by x-ray diffraction, whereas a-C(:H):Si still possesses an amorphous character. Raman scattering spectra show higher I(D)/I(G) ratios for hydrogen-free a-C(:X) films compared to the respective a-C(:H):X, indicating a higher number and larger sizes of sp2 clusters in the carbon network. For the hydrogenated a-C:H:X films, the reduced number of sp2 clusters is related to the presence of terminating CH bonds, which were detected as stretching modes. Among the different films, a-C:W has the highest I(D)/I(G) ratio, while a-C:H and a-C:H:Si exhibit the lowest I(D)/I(G) values. While a-C:Si and a-C:H:Si are characterized by comparable hardness values of (18.7 ± 1.3) and (18.4 ± 1.1) GPa, a-C:W has a lower hardness of (13.8 ± 1.0) GPa compared to a-C:H:W with (17.5 ± 0.9) GPa. Among all modified a-C(:H):X films, a-C:Si and a-C:H:Si reveal the lowest coefficients of friction, but show highest wear rates in dry sliding against 100Cr6 steel. Contrarily, a-C:W has higher friction and wear than a-C:H:W. Consequently, the Si-containing a-C(:H):Si films demonstrate comparable tribo-mechanical properties, while the hydrogenation state leads to different tribo-mechanical properties of a-C(:H):W.

Tribological Behavior of Aluminum Hybrid Nanocomposites Reinforced with Alumina and Graphene Oxide

Due to rapid technological advancements, the demand for lightweight materials with improved tribo-mechanical properties is continuously growing. The development of composite materials is one of the routes taken by researchers to meet these target properties. Aluminum (Al) is one of the most suitable materials used for developing composites for a wide range of applications because of its light weight, high conductivity, and high specific strength. In this study, aluminum hybrid nanocomposites with alumina (10 Vol% Al2O3) and varying loadings of graphene oxide (0.25, 0.5 and 1 wt% GO) were fabricated using the spark plasma sintering technique. The tribological properties of the developed hybrid composites were evaluated by conducting ball-on-disk wear tests at a normal load of 3N, with a sliding speed of 0.1 m/s, and for a sliding distance of 100 m. A 440C hardened stainless steel ball with a diameter of 6.3 mm and a hardness of 62 RC was used as a counterface. Scanning electron microscopy (SEM), elemental X-ray dispersive analysis (EDS), and optical profilometry were used to ascertain the involved wear mechanisms. The results revealed that Al-10 Vol%Vol% Al2O3-0.25 wt% GO hybrid nanocomposite showed an increase of 48% in the hardness, a reduction of 55% in the specific wear rate, and a reduction of 5% in COF compared with pure aluminum.