Study on Mechanical and Wear Behaviour of AA7075/TaC/Si3N4/Ti Hybrid Metal Matrix Composites

This research article focuses on the development of AA7075 alloy reinforced with different wt% of Tantalum Carbide (TaC), Silicon Nitride (Si3N4) and Titanium (Ti) particulates using stir casting. Mechanical characteristics like tensile, compression and microhardness of the developed composites were analysed. High temperature tribological properties of the hybrid MMCs were studied for various input control factors like sliding speed, load and temperature. Design analysis has been executed by Taguchi orthogonal array and ANOVA (Analysis of Variance). The incorporated reinforcements exhibited improved wear resistance at ambient temperature along with elevated temperatures. Monolithic dissemination of reinforcement’s in the prepared composites magnifies the mechanical and tribological characteristics for composites compared to matrix material. From the optimization technique, it was witnessed that Wear Rate and Frictional Coefficient are afflicted by temperature go after load & sliding speed. The optimal amalgamation of control parameters of distinct tribo-responses has been detected.

Increasing the Efficiency of Food Material Cutting during Inclined and Shear Movements of Knife

Mathematical models for predicting the resistance forces that are developed during the inclined and sliding cutting of food materials have been developed. The dependence of the actual cutting angle on the angle of inclination and sliding speed of the cutting edge at various sharpening angles have been investigated. For the inclined cutting mode, the dependence of the useful resistance force on the cutting speed has been determined at various angles of inclination of the cutting edge and designed sharpening angles. For the sliding cutting mode, the dependence of the useful resistance force on the feeding speed has been demonstrated at various sliding speed values and designed knife sharpening angles. The dependence of the transformed dimensionless sharpness of the knife on the angle of inclination of the cutting edge and the sliding speed has been established for different constructional sharpness values of the knife. The results of the study indicate that the useful resistance force is significantly reduced during the inclined and sliding cutting processes when compared with the normal cutting process, and a change in the pattern of fiber destruction, which significantly increases the cutting efficiency of cutting tools, is obtained.

Optimization and analysis of dry sliding wear process parameters on cellulose reinforced ABS polymer composite material

Purpose This study aims to the optimization using three factors and three-level parameters (sliding speed [rpm], sliding distance [m/s] and load [N]) of design matrix were adapted to Box–Behnken design using design expert v8.0 software. Based on the parameters, to develop the linear regression equation and to find the significant considerable wear process parameters based on output responses like wear loss (WL) and coefficient of friction (COF) value of polymer matrix composites (PMC) specimen of Acrylonitrile-butadiene-styrene (ABS)/cellulose composite (80 wt% of ABS and 20 wt% of cellulose). Design/methodology/approach The fabrication of the ABS/cellulose composite sample was carried out by the simple hands-on stir process method. As per the American Society for Testing and Materials G99 standard, the sample was made by the molding process. The wear analysis was made by multi tribotester TR25 machine and validated the developed model by using statistical software design expert v.8.0 and numerical tools like analysis of variance. The surface morphology [field emission scanning electron microscopy (FESEM) analysis] of the sample was also observed using the Quanta FEG-250 FESEM instrument. Findings The parameters like sliding speed, sliding distance and load are independently affected the COF value and WL of the 80% of ABS matrix and 20% cellulose reinforced composite material. The regression equations were generated by the coefficient of friction value and WL, which predicted the minimum WL of 80% of ABS matrix and 20% of cellulose reinforced composite material. The worn surface analysis result exposes the worn path and equal distribution of reinforcement and matrix on the surface of composite material. Originality/value The literature survey revealed a small number of studies available regarding wear analysis of ABS matrix and cellulose reinforced composite materials. In the present work, to fabricate and evaluate the wear performance of PMC (80% of ABS and 20% of cellulose) depends on the WL and COF value. The maximum and minimum COF value (µ) of 80% of ABS and 20% of cellulose composite material is 4.71 and 0.28 with the optimized wear process parameter by 1,000 mm of sliding distance, 0.25 (m/s) of sliding speed and 9 N of load.

Hydrodynamic Lubrication of Partially Textured Gas Parallel Slider Bearings with Orientation Ellipse Dimples

The hydrodynamic lubrication performance of partially textured gas parallel slider bearings with orientation ellipse dimples is investigated in this paper. By using the multigrid finite element method, the pressure distribution between a partially textured slider and a smooth slider is obtained. The geometric parameters of the ellipse dimples are optimized to maximize the average pressure under a given sliding speed. The numerical results show that geometric parameters such as orientation angle, depth, slender ratio, and area density have an important impact on hydrodynamic pressure. Besides, the effect of textured fraction on hydrodynamic pressure is investigated under a given sliding speed. It is observed that the optimum textured fraction for maximizing the average pressure is dependent on the sliding speed.

Influence of Nanographite on Dry Sliding Wear Behaviour of Novel Encapsulated Squeeze Cast Al-Cu-Mg Metal Matrix Composite Using Artificial Neural Network

This paper investigates the dry sliding wear behaviour of squeeze cast Al-Cu-Mg reinforced with nanographite metal matrix composites. The experimental study employed the Taguchi method. The Taguchi method plays a significant role in analyzing aluminium matrix composite sliding tribological behaviour. Specifically, this method was found to be efficient, systematic, and simple relative to the optimization of wear and friction test parameters such as load (10, 20, and 30), velocity (0.75, 1.5, and 2.25 m/s), and nanographite (1, 3, and 5 wt%). The optimization and results were compared with the artificial neural network. An orthogonal array L27 was employed for the experimental design. Analysis of variance was carried out to understand the impact of individual factors and interactions on the specific wear rate and the coefficient of friction. The wear mechanism, surface morphologies, and composition of the composites have been investigated using scanning electron microscopy with energy-dispersive X-ray spectroscopy. Results indicated that wt% addition of nanographite and increase of sliding speed led to a decrease in the coefficient of friction and wear rate of tested composites. Furthermore, individual parameter interactions revealed a smaller impact. The interactions involved wt% of nano-Gr and sliding speed, sliding speed and normal load, and wt% of nano-Gr and normal load. This inference was informed by the similarity between the results obtained ANN, ANOVA, and the experimental data.

Tribological behaviour of lamb bone ash and boron carbide reinforced ZA-27 hybrid metal matrix composites under dry sliding conditions

This study aims to investigate the tribological behaviour of lamb bone ash (LBA) and boron carbide (B4C) reinforced ZA-27 hybrid metal matrix composites fabricated using a stir casting process. The weight percentage of LBA and B4C particles in the composites were varied from 0-5 wt.%. The composites have been evaluated for density, porosity and microhardness before tribological testing. Dry sliding friction and wear behaviour of composites were studied on a pin-on-disc tribometer by varying load from 10-50 N at a fixed sliding speed of 1 m/s. Also, to investigate the effect of sliding speed on friction and wear behaviour of composites, tests were carried out at 2 m/s and 3 m/s of sliding speed. A scanning electron microscope (SEM) was used for examining the microstructure and worn surface morphology of composite samples. SEM micrographs revealed the presence and homogeneous distribution of reinforcement particles, and energy-dispersive X-ray spectroscopy (EDS) analysis confirmed the presence of LBA and B4C particles in the composites. Composites density decreased, and porosity increased with the addition of reinforcement particles. The microhardness of the 5 wt.% reinforced LBA composite improved by 18.38%, whereas hybrid composite containing (2.5 wt.% LBA + 2.5 wt.% B4C) showed an improvement of 42% compared to the base alloy. The coefficient of friction (COF) and wear loss increased with the increase in load, whereas COF decreased and wear loss increased with the increase in sliding speed. Composites showed superior wear resistance even at higher loads and sliding speeds. SEM micrographs of worn surface revealed adhesion and abrasion type of wear mechanisms. Therefore, with the improvement in wear resistance this developed composite can be used as a bearing material over monolithic ZA-27 alloy in the automotive sector.

Sliding wear characteristics of a-C:H:SiOx coatings

The paper presents the experimental study of the friction and wear characteristics of amorphous carbon coating containing hydrogen and SiOx (a-C:H:SiOx) deposited onto WC-8Co cemented carbide substrates. A 5 μm thick a-C:H:SiOx coating was fabricated using plasma-assisted chemical vapor deposition. The tribological properties of the a-C:H:SiOx coating sliding in contact with WC–8Co, ZrO2, SiC, Si3N4 counter bodies, are examined using the ball-on-disc method at different normal loads and sliding speeds. Tribology testing shows that the minimum values of the friction coefficient (0.044) and the wear rate (9.3×10−8 mm3/Nm) are observed when using a counter body made of silicon nitride at a 5 N indentation load. The load increase from 5 to 12 N raises the friction coefficient up to 0.083 and the wear rate up to 46×10−8 mm3/Nm. When the sliding speed reaches its critical value, the coating friction provides the transition from sp3 hybridized to sp2 hybridized and polymeric carbon, which is accompanied by the reduction in the friction coefficient. The a-C:H:SiOx coating provides an increase in the critical sliding speed up to 50–75 mm/s, which exceeds that of non-alloyed (a-C and a-C:H) diamond-like carbon coatings as a result of doping by silicon and oxygen.

Effect of Micro-Textured Surfaces and Sliding Speed on the Lubrication Mechanism and Friction-Wear Characteristics of CF/PEEK Rubbing against 316L Stainless Steel under Seawater Lubrication

In this work, the lubrication mechanism and friction-wear characteristics of the friction pair between carbon-fiber-reinforced polyether ether ketone (CF/PPEK) and 316L stainless steel with a micro-hemispherical pit textured surface at different sliding speeds under seawater lubrication were studied through numerical simulation and experimental investigation. The study results indicate that the seawater moves following the sliding direction of the upper specimen, forms a vortex ring flow in the hemispherical pit of the bottom specimen, uses the convergent gap to generate a hydrodynamic effect, produces the bearing capacity, and realizes fluid lubrication. The hemispherical pit diminishes the abrasive wear during the friction process by storing the wear debris, and the main wear forms of the hemispherical-pit surface friction pair are oxidative wear and adhesive wear. The friction coefficient of the hemispherical-pit surface friction pair is 0.018–0.027, the specimen contact temperature is 40.2–55.1 °C, and it is always in the hydrodynamic lubrication state in a rotation speed ranging from 1000 r/min to 1750 r/min. As the sliding speed increases, the specimen contact temperature climbs, and the oxidation reaction gradually becomes full. Oxidative wear and adhesive wear alternately play a dominant role in the friction, and the wear rate first decreases and then increases sharply.