Synergistic Effect of Heat Treatment and Graphene/ZrO 2 Addition on the Mechanical and Tribological Properties of Al7075‐Based Hybrid Composites

This study reports on silicon nitride (Si3N4) and graphene nanoplatelets binary powder reinforced hybrid titanium composites obtained by a powder metallurgy method. Si3N4 powder was added at 3 wt.% and graphene nanoplatelets were added in various amounts (0.15, 0.30, 0.45, 0.60 wt.%) in the titanium matrix. Density, micro-Vickers hardness, compressive behavior, wear properties and microstructure of the hybrid composites were evaluated. Addition of different percentages of graphene nanoplatelets and 3 wt.% Si3N4 to the titanium matrix composites significantly enhanced mechanical properties. The highest hardness (634 HV) and compressive strength (1458 MPa) values were measured for 0.15 wt.% graphene nanoplatelets and 3 wt.% Si3N4 added titanium hybrid composite. The lowest mass loss and wear rate (Δm = 4 mg, W = 6.1×10–5 mm3 (N m)–1) values were measured for the same 0.15 wt.% graphene nanoplatelets and 3 wt.% Si3N4 added titanium hybrid composite compared with pure Ti.

Thermal barrier coatings (TBCs) are advanced ceramic layers applied to metal components to provide insulation and protection against high temperatures in extreme operating environments. This study investigated the effects of graphene nanoplatelet (GNP) reinforcement on samarium niobate (SN: SmNbO4) TBCs for extreme environments. Four ceramic top coat compositions were plasma-sprayed onto Inconel 718 substrates: Yttria-stabilized zirconia (YSZ), SmNbO4 (SN), and SN reinforced with 1 and 1.5 wt% GNPs (SN-1GNP, SN-1.5GNP). The research examined microstructural characteristics, phase evolution, mechanical properties and toughening mechanisms. GNP reinforcement significantly improved coating density, with SN-1.5GNP reaching 97.4 ± 1.64% compared to 91.3 ± 1.69% for SN and 86.6 ± 1.47% for YSZ. Hardness and elastic modulus were enhanced by 86.38% and 57.91% for SN-1GNP, and 101.09% and 65.23% for SN-1.5GNP respectively. Moreover, fracture toughness experienced a significant increase from 1.86 ± 0.4 to 5.48 ± 0.7 MPa·m1/2, facilitated by toughening mechanisms, like splat bridging, GNP pull-out, crack arrest and ferroelastic domain switching. Additionally, the SN-1.5GNP coating exhibited a higher adhesion strength of 36.84 MPa, thereby leading to improved layer distribution and lesser chance of delamination. Compared to YSZ, these findings suggest that GNP-reinforced SN coatings offer enhanced performance for extreme environment applications.

In the present study, the effect of graphene nanoplatelet (GNP) reinforcement in Aluminum material at different rates was investigated on tribological properties. In this scope, the samples were produced by the hot press under determining different production parameters. The wear characteristics of the composites were determined using the ball-on disc wear test method. Ball on disc wear test showed that the Al6061/GNPs composite which was produced with the addition of 1 wt% GNPs, a sintering temperature of 600 °C, and a sintering time of 45 min, had the best wear resistance. Thanks to the GNPs reinforcement, a 61 % reduction in wear rate was achieved when compared to the non-reinforced Al material. The effects of the production parameters on the friction coefficient were investigated using the Taguchi method and it was determined that the most important parameter affecting the friction coefficients of the composites was the wt % GNPs addition. The results showed that the addition of GNPs is an important reinforcing material that reduces the wear rate when added to the structure at certain rates.

Analysis and active control of geometrically nonlinear responses of smart FG porous plates with graphene nanoplatelets reinforcement based on Bézier extraction of NURBS

Lightweight advance composites are the new emerging class of the engineering materials that are rapidly replacing a large category of conventional material for various aerospace, automotive, structural industrial and marine applications because of excellent tribological as well as mechanical properties. The scope and objectives are to investigate tribological properties of the hybrid aluminium composite under lubricated sliding conditions. In this concern, lightweight aluminium hybrid composite is fabricated using non-conventional spark plasma sintering (SPS) route. The tribological behaviour of hybrid composite sample is examined using a ball-on-disc reciprocating universal tribometer configuration for 120 m sliding distance for variable load 10–80 N for 2 mm stroke and reciprocating frequency of 30 Hz. Wear test sliding distance is also performed for the (90–450 m) sliding distance. Two variable lubricants, i.e. Base PAO-4 lubricant and commercial SAE2W50 lubricant, are used in the present study. From the results, it is observed that the commercial SAE20W50 lubricant shows superior tribological properties with the fabricated sample and exhibit min coefficient of friction (COF) and wear rate. Abrasion and delamination are the main wear mechanisms that cause the removal of material while tribological testing. Reduction in the COF is attributed to the 2D graphene nanoplatelets (GNP) reinforcement in the composite samples that cause easy sliding due to weak van der Waals force and hence provide the exceptional lubrication mechanism for the composite sample.

Water absorption mechanism and mechanical performance of adhesively joint aluminum alloy with GNP reinforced epoxy

Effect of compressive strength and tensile reinforcement ratio on flexural behavior of high-strength concrete beams

Effect of physio-chemically functionalized graphene nanoplatelet reinforcement on tensile properties of aluminum nanocomposite synthesized via spark plasma sintering

Abstract

The effect of the hybridization of basalt and carbon fabrics on physical and mechanical properties of the thick carbon and basalt hybrid woven composites manufactured by compression molding was investigated in this study. Monotype (all carbon and all basalt) and their hybrid woven fabric layer combinations were used to reinforce polyester resin. However, the effect of the Graphene Nanoplatelets (GNPs) reinforcement was also examined in polyester matrix by adding different volume fractions between 0.1 and 2 wt.-%. Afterward, the optimized GNPs at the ratio of 0.1 wt.-% was used in one of the hybrid composite combinations (10C10BGNP) in order to improve fiber matrix adhesion. The specimens were subjected to three different tests including tensile, flexural and impact tests as well as morphological characterization by SEM and XRD. Results showed that tensile strengths of thick carbon/basalt hybrid composites are higher than the tensile strengths of thick monotype carbon and basalt composites. The best tensile properties were achieved in 14C6BP hybrid composites while the highest flexural performance of 501 MPa and the highest impact energy of 14.32 J was achieved in 10C10BP hybrid composites with the addition of GNPs. Moreover, the ratio of the basalt fiber content increased the impact energy of hybrid composites to a level comparable to that of all basalt fiber composites.

Improved mechanical and wear properties of hybrid Al-Al2O3/GNPs electro-less coated Ni nanocomposite

This paper presents, for the first time, the mechanical model and theoretical analysis of free vibration of a spinning functionally graded graphene nanoplatelets reinforced composite (FG-GPLRC) porous double-bladed disk system. The nanocomposite rotor is made of porous metal matrix and graphene nanoplatelet (GPL) reinforcement material with different porosity and nanofillers distributions. The effective material properties of the system are graded in a layer-wise manner along the thickness directions of the blade and disk. Considering the gyroscopic effect, the coupled model of the double-bladed disk system is established based on Euler–Bernoulli beam theory for the blade and Kirchhoff’s plate theory for the disk. The governing equations of motion are derived by employing the Lagrange’s equation and then solved by employing the substructure mode synthesis method and the assumed modes method. A comprehensive parametric analysis is conducted to examine the effects of the distribution pattern, weight fraction, length-to-thickness ratio, and length-to-width ratio of graphene nanoplatelets, porosity distribution pattern, porosity coefficient, spinning speed, blade length, and disk inner radius on the free vibration characteristics of the FG-GPLRC double-bladed disk system.

BackgroundMost contemporary total disc replacements (TDRs) use conventional orthopaedic bearing couples such as ultrahigh-molecular-weight polyethylene (polyethylene) and cobalt-chromium (CoCr). Cervical total disc replacements incorporating polyetheretherketone (PEEK) bearings (specifically PEEK-on-PEEK bearings) have been previously investigated, but little is known about PEEK-on-ceramic bearings for TDR.Questions/purposes(1) What is the tribologic behavior of a PEEK-on-ceramic bearing for cervical TDR under idealized, clean wear test conditions? (2) How does the PEEK-on-ceramic design perform under impingement conditions? (3) How is the PEEK-on-ceramic bearing affected by abrasive wear? (4) Is the particle morphology from PEEK-on-ceramic bearings for TDRs affected by adverse wear scenarios?MethodsPEEK-on-ceramic cervical TDR bearings were subjected to a 10 million cycle ideal wear test based on ASTM F2423 and ISO 181912-1 using a six-station spine wear simulator (MTS, Eden Prairie, MN, USA) with 5 g/L bovine serum concentration at 23° ± 2° C (ambient temperature). Validated 1 million cycle impingement and 5 million cycle abrasive tests were conducted on the PEEK-on-ceramic bearings based, in part, on retrieval analysis of a comparable bearing design as well as finite element analyses. The ceramic-on-PEEK couple was characterized for damage modes, mass and volume loss, and penetration and the lubricant was subjected to particle analysis. The resulting mass wear rate, volumetric wear rate, based on material density, and particle analysis were compared with clinically available cervical disc bearing couples.ResultsThe three modes of wear (idealized, impingement, and abrasive) resulted in mean mass wear rates of 0.9 ± 0.2 mg/MC, 1.9 ± 0.5 mg/MC, and 2.8 ± 0.6 mg/MC, respectively. The mass wear rates were converted to volumetric wear rates using density and found to be 0.7 ± 0.1 mm3/MC, 1.5 ± 0.4 mm3/MC, and 2.1 ± 0.5 mm3/MC, respectively. During each test, the PEEK endplates were the primary sources of wear and demonstrated an abrasive wear mechanism. Under idealized and impingement conditions, the ceramic core also demonstrated slight polishing of the articulating surface but the change in mass was unmeasurable. During abrasive testing, the titanium transfer on the core was shown to polish over 5 MC of testing. In all cases and consistent with previous studies of other PEEK bearing couples, the particle size was primarily < 2 µm and morphology was smooth and spheroidal.ConclusionsOverall, the idealized PEEK-on-ceramic wear rate (0.7 ± 0.1 mm3/MC) appears comparable to the published wear rates for other polymer-on-hard bearing couples (0.3–6.7 mm3/MC) and within the range of 0.2 to 1.9 mm3/MC reported for PEEK-on-PEEK cervical disc designs. The particles, based on size and morphology, also suggest the wear mechanism is comparable between the PEEK-on-ceramic couple and other polymer-on-ceramic orthopaedic couples.Clinical RelevanceThe PEEK-on-ceramic bearing considered in this study is a novel bearing couple for use in total disc arthroplasty devices and will require clinical evaluation to fully assess the bearing couple and total disc design. However, the wear rates under idealized and adverse conditions, and particle size and morphology, suggest that PEEK-on-ceramic bearings may be a reasonable alternative to polyethylene-on-CoCr and metal-on-metal bearings currently used in cervical TDRs.

Enhancing fire resistance in geopolymer concrete containing crumb rubber with graphene nanoplatelets

Mechanical and corrosion properties of graphene nanoplatelet–reinforced Mg–Zr and Mg–Zr–Zn matrix nanocomposites for biomedical applications