Brijesh Gangil

Thermal stability analysis of nano-particulate-filled phenolic-based friction composite materials

This research article reports the thermal stability behaviour of nano-particulates (multiwalled carbon nanotube and nanoclay)–filled Kevlar-lapinus fibre-reinforced phenolic resin–based friction composite under oxygen atmosphere using thermogravimetric analysis. To analyse the damage assessment of the proposed nano-particulates–filled composites under thermal surroundings, the thermograph of the composites are generally divided into three major temperature zones (i.e. zone-1, zone 2 and zone-3). Temperature of zone-1 ranges from 30℃ to 350℃, zone-2 from 350℃ to 600℃ and finally zone-3 from 600℃ to 900℃. It has also been noticed that in zone-1 the friction composite shows relatively lower magnitude of thermal stability; thereafter, the decomposition rate accelerates with steep drop in thermal stability in zone-2. As heat supply continued to zone-3, the composite degradation rate gradually accelerates. The incorporation of nano-particulates indicated a remarkable improvement in the thermal stability of Kevlar/lapinus fibre combination reinforced friction composites. Furthermore, the result shows that nanoclay surpassed multiwalled carbon nanotube with regard to the thermal stability of friction formulations. This investigation confirms that nano-particulates–filled Kevlar/lapinus fibre-reinforced friction composites possess excellent potential to be used as high temperature–resistant friction materials.

Investigations on mechanical and sliding wear behaviour of short fibre-reinforced vinylester-based homogenous and their functionally graded composites

Now-a-days, short fibre-reinforced functionally graded polymer composites are used in numerous structural applications. This article presents the investigation on mechanical and sliding wear characteristics of short Kevlar fibre-reinforced vinylester resin homogenous and its functionally graded polymer composites. The composites are fabricated by simple mechanical stirring (for homogeneous) and vertical centrifugal casting technique (for graded), respectively. Among the investigated physical and mechanical characteristics, the characteristics like void-fraction, hardness and flexural strength are found to be enhanced in the case of functionally graded materials than homogeneous composites, and this increases with fibre loading. Similarly, the characteristics like tensile strength and impact strength are found to be deteriorated in case of functionally graded materials than homogeneous composites, and this increases with fibre loading. At the end, dry sliding wear behaviour are determined experimentally on pin-on-disk type friction and wear monitoring test rig, under abrasive medium environment. The designed parameters used are sliding velocities (1.5–4.5 m/s), fibre loading (0–20 wt%), normal loads (10–25 N), sliding distance (1–4 km) and abrasive grit size of 18–48 µm that creates abrasive medium. It is observed that for similar test conditions functionally graded materials exhibit much higher wear resistance than homogeneous composites. Sliding wear characteristics and their significant factor settings are successfully analysed using statistics-based Taguchi experimental design. Finally, dynamic mechanical properties of the investigated homogenous/functionally graded materials composites are studied in order to investigate the overall flexibility and interaction of the constituents, so as to improve the specific wear rate. Storage modulus of the composites improves with Kevlar fibre loading. Graded composites in most cases exhibits higher storage modulus than homogeneous composites. Surface morphology studies reveal the dynamics of erosion wear and underlying micro-mechanisms that serve as determinant for wear performance of such composites.

Laser assisted rapid manufacturing technique for the manufacturing of functionally graded materials

Functionally Graded Material (FGM) is a material with engineered gradients of composition, structure and/or specific properties aiming to become superior over homogeneous material composed of same or similar constituents. In the recent years, research has been undertaken on manufacturing of functionally graded materials (FGM) using numerous techniques like powder metallurgy, melt processes, centrifugal casting, electrophoretic deposition, spark plasma sintering, physical vapor deposition, chemical vapor deposition etc. Most of these techniques may be well suited for a specific application yet they suffer from one or more limitations like lower graded thickness, low deposition rate, complexity in process requirement, or high processing cost. To circumvent these limitations innovative technique called laser assisted manufacturing technique is applied for manufacturing functionally graded materials. Three methods that employ Laser for synthesis of FGM is elaborated in this work (i) 3-D Laser Cladding, (ii) LENS and (iii) Selective laser sintering. Laser Cladding is used for obtaining coatings of FGM by direct powder injection into the laser beam. 3-D Laser-engineered net shaping (LENS) is used to fabricate FGM directly from CAD solid models and thus further reduce the lead times for metal art fabrication. Selective laser sintering (SLS) is a layered manufacturing based freeform fabrication approach for constructing three dimensional structures in functionally graded composites. All these methods are used to manufacture FGMs in a short interval of time and the process can be controlled digitally, thus all these methods come in the heading of rapid manufacturing (RM). These methods have a huge industrial potential and can be commercialized for manufacturing bulk FGM.

Mechanical and wear behavior of vinyl ester-carbon/cement by-pass dust particulate filled homogeneous and their functionally graded composites

Abstract The paper presents the processing, mechanical and sliding wear characterization of particulate filled cement by-pass dust and carbon fiber (fixed) reinforced homogeneous and functionally graded vinyl ester composites. Homogeneous and graded composites are fabricated by simple mechanical stirring and vertical centrifugal casting technique, respectively. Among the physical and mechanical properties, void content, hardness and impact strength are found to increase with increase in filler content in case of functionally graded materials (FGMs), whereas tensile strength and flexural strength are found to deteriorate for both FGMs and homogeneous composites as compared to the neat composites. Sliding wear characteristics are studied with the help of pin-on-disc test employing the design of experiments approach based on Taguchi’s orthogonal arrays. The present study reveals that graded composites exhibit good mechanical and wear characteristics compared to homogeneous composites. Scanning electron microscopy confirms the dispersion of carbon fiber in the matrix in graded composites.

Structural and physico-mechanical characterization of closed-cell aluminum foams with different zinc additions

Abstract Closed-cell aluminum foams with different percentages of zinc content were successfully prepared and investigated. The foamable precursors were prepared in a pit furnace by adding calcium as thickening agent, calcium carbonate as blowing agent and different percentages (0 wt.%, 0.5 wt.% and 1 wt.%) of zinc particles at 650–750°C. The distribution of Zn elements and quassi-static behavior of the foams at room temperature were investigated. The experimental results show that Zn element is uniformly distributed in cell wall matrix. The distribution of Zn elements had a significant effect on the quasi-static compressive behavior of aluminum foams; from the results, it is obvious that zinc-containing foams possessed higher compressive strength and energy absorption capacities than pure aluminum foams. Hence, it can be concluded that increase in percentage of Zn particles helps to increase the compressive strength, plateau region and energy absorption, in addition to providing better and uniform pores.

Physico-mechanical and erosive wear analysis of polyester fibre-based nonwoven fabric-reinforced polymer composites

The research work aims to study the physico-mechanical and erosive wear behaviour of polyester fibre-based needle-punched nonwoven fabric mat reinforced epoxy composites. Therefore, the epoxy composites with varying proportion of polyester fibre-based needle-punched nonwoven fabric mat were fabricated and characterized for their physical, mechanical and erosive wear properties. The experimental results indicated that the increase of fibre content enhanced the physical and mechanical properties of the composites. To optimize and improve the erosive wear performance of fabricated composites, the Taguchi method was implemented. For this, L27 orthogonal array was constructed to examine the influence of the five control factors including impingement angle, impact velocity, stand-off distance, fibre content and erodent size. The experimental schedule was carried out in an air jet erosion test rig. The results indicate that the impact velocity emerges as the most significant control factor affecting the erosive wear of fabricated composites. Finally, the possible erosive wear mechanisms were studied by examining the composites eroded surfaces with scanning electron microscopy.

Experimental investigation of machining process parameters in conventional turning of Al-7075 on MRR using response surface methodology

Lathe machine is the basic machine used for all type of material removal process used to manufacture components with complicated shape and profile. A lathe is a machine tool which rotates the workpiece on its axis to perform the various operations with tools that are applied to the workpiece to create an object which has a symmetry about an axis of rotation. The effect of various process parameters of conventional lathe like feed rate, depth of cut, spindle speed for turning operation on AL-7075 have been investigated to reveal their impact on output parameter i.e. Material Removal Rate(MRR), Surface Roughness(SR) using response surface methodology. Experimental plan is performed by a standard RSM design called BOX BEHKEN design. The result of analysis of variance (ANOVA) indicate that the proposed mathematical model adequately describe the performance within the limit of factors being studied. The optional set of parameters have also been predicted to maximize the material removal rate.

Physico-mechanical and tribological properties of Grewia Optiva fiber/bio-particulates hybrid polymer composites

Lack of resources and increasing environmental issues has received widespread attention for the development of natural fiber/ particulate reinforced hybrid polymer composites. In the present investigation the authors use (GO) Grewia Optiva as the main reinforcement and rice husk/wheat straw as additional particulates for improving the mechanical and wear properties of polymer composites. The samples were prepared by hand layup technique according to ASTM standards. The results indicated that incorporation of wheat straw with GO polymer materials exhibited better hardness (2.5 times harder) and less wear (0.85 times) than mono GO fiber polymer composites (GOFRP). Moreover, Rice husk filled GOFRP shows superior impact energy among the all set of composites. Water absorption behavior was also discussed in this investigation.

Thermo-mechanical and sliding wear behaviour of vinyl ester–cement by-pass dust particulate-filled homogenous and their functionally graded composites

In this article, particulate-filled cement by-pass dust and short Kevlar fibre have been utilised to produce homogenous and functionally graded vinyl ester composites. In this study, cement by-pass dust varies from 4 to 12 wt% whereas the Kevlar fibre is kept fixed (i.e. 10 wt%). The physical and mechanical properties like void content and hardness are found to increase with increase in filler content in case of functionally graded materials, whereas tensile strength, impact energy and flexural strength are found to deteriorate for both functionally graded materials and homogeneous composites. Similarly, sliding wear tests are performed over a range of sliding velocities (1.5–4.5 m/s), normal loads (10–25 N), filler contents (4–16 wt%), sliding distance (1–4 km) and abrasive grit size (18–48 µm) using pin on disc test rig. Wear characteristics and their significant factor are successfully analysed using statistics-based Taguchi experimental design and analysis of variance, respectively. Dynamic mechanical analysis is carried out for homogenous and functionally graded materials composites in order to investigate the overall flexibility and interaction of the constituents. Finally, surface morphology of the worn surfaces was studied with the help of scanning electron microscope.