Assimilation of Nanoparticles of SiC, ZrC, and WC with Polyaryletherketone for Performance Augmentation of Adhesives.

The present paper reports the analyses of results obtained from experiments carried out to explore the challenge of homogeneous, uniform, and deagglomerated dispersion of ultra-heavy nanoparticles (NPs) in the high-performance polyaryletherketone (PAEK) matrix. An equal and fixed amount of (0.5 vol. %) NPs of silicon carbide (SiC), zirconium carbide (ZrC), and tungsten carbide (WC) were dispersed in a PAEK matrix and compression molded to develop three different nanocomposites. Simultaneously, nano-adhesives of the same composition were also developed to join the stainless steel adherends. The composites and adhesives were characterized for their physical, thermal, thermo-mechanical, thermal conductivity (TC), and lap shear strength (LSS) behavior. It was observed that SiC NPs performed significantly better than ZrC and WC NCs in all performance properties (LSS: 154%, TC: 263%, tensile strength: 21%). Thermal conductivity (TC) and tensile properties were validated using various predictive models, such as the rule of mixture parallel model, the Chiew and Glandt model, and the Lewis model. Scanning electron micrographs were used for the morphological analysis of LSS samples to detect macro- and micro-failure. Micrographs showed evidence of micro-striation and plastic deformation as a micromodel, as well as mixed failure, i.e., adhesive-cohesive as a macro-failure mode.

Carbon Fabric Decorated with In-Situ Grown Silver Nanoparticles in Epoxy Composite for Enhanced Performance.

The current study focuses on studying the effect of reinforcement of carbon fabric (CF) decorated with in-situ grown silver (Ag) nanoparticles (NPs) on the performance properties of epoxy composite. The Ag NPs were grown on carbon fabric by reducing silver nitrate. The main objective of developing such an innovative reinforcement was to improve thermal conductivity, interlaminar strength, and tribological properties of CF-epoxy composites. The growth of NPs on the surface of CF was confirmed through scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDAS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction studies. The development of composites was conducted by the impregnation method, followed by compression molding. It was observed that in-situ growth of Ag NPs enhanced thermal conductivity by 40%, enhanced inter-laminar shear strength by 70%, enhanced wear resistance by 95%, and reduced the friction coefficient by 35% in comparison to untreated CF.

Suppression of Brake Noise and Vibration Using Aramid and Zylon Fibers: Experimental and Numerical Study.

Aramid pulp/fiber is the most vital ingredient of brake friction material (FM) formulation. It is perpetually added to achieve quality brake pads/shoes and improve the overall friction and wear performance. Additionally, novel Zylon fibers have a superior property to aramid fibers. However, no studies give insights on their influence on brake noise and vibration (NV) performance. In the current work, a series of six different types of eco-friendly brake pads was developed. The first five contain aramid pulp, aramid short fibers, and Zylon fibers of different sizes (1, 3, and 6 mm) as the theme ingredients (3 wt %) by keeping the parent composition identical. Additionally, one more pad was developed that contains no aramid/Zylon fibers (i.e., reference pad). The pads were characterized for physical and mechanical properties. The damping and natural frequencies of pads were measured experimentally and numerically. All brake pads were evaluated for detailed NV performance by following the SAE J 2521 test schedule. In addition, numerical simulation was performed to validate the experimental brake squeal results. Results revealed that aramid/Zylon fiber-based pads improved the porosity, damping, and compressibility. Overall, brake noise and vibrations were improved for aramid/Zylon fiber-based pads by 1.2-1.5 dBA and 20-25%, respectively, compared to the reference pad. The complex eigenvalue analysis (CEA) proved that squeal was mainly influenced by the damping and density of the pad materials. Thus, aramid/Zylon fiber-based pads can effectively suppress the instability of the brake system and reduce the brake squeal propensity.

Performance Augmentation of Epoxy Adhesives with TiN Nanoparticles.

In the current study, nanoparticles (NPs) of titanium nitride (50-70 nm) in varying amounts (0-4 wt %) were uniformly suspended in an epoxy solution and then used to cast the films of nanocomposites. The same formulations were used to prepare the lap shear strength joints using stainless-steel coupons with the help of standard molds and then employing the compression molding technique. The nanocomposites films were characterized for their physical properties, thermal stability, friction performance, and scratch hardness, while the lap shear strength of joints prepared using nanocomposites as nanoadhesives was evaluated. The failed surfaces of joints were investigated using scanning electron microscopy (SEM) to understand the failure modes, that is, micro-failure mechanisms, while the cross-sectional surfaces of fractured nanocomposites were investigated using SEM to identify the distribution of NPs. The increase in the contents of NPs in the epoxy led to an almost linear increase in the selected performance properties. The highest (70%) improvement in the lap shear strength was observed with 4 wt % NPs, which was correlated with an increase in the hardness of composites.

Carbon Nanoparticles of Varying Shapes as Additives in Mineral Oil Assessment of Comparative Performance Potential.

In this work, carbonaceous nanoparticles (NPs) of varying morphology, viz., multilayer graphene (lamellar, thickness ∼ 3-7 nm), graphite (spherical ∼70 nm), and multi-walled carbon nanotubes (tubular), were selected to explore their tribo-potential in oil under identical operating conditions. A series of nano-oils were prepared using API group III mineral base oil with a dispersant (1%) and selected NPs in incremental concentration (0.5-4%). The tribo-performance of oils was evaluated on a four-ball tester and SRV-IV for extreme-pressure, antiwear (AW), and antifriction performance. Formulations were characterized for density, viscosity, and viscosity index. The stability of oils was monitored through visual observation weekly. Results revealed that the graphene particles showed excellent wear-preventive ability as an AW additive with (41-50) % increase followed by nanographite. Worn surfaces were studied to understand the plausible wear mechanism using a different spectroscopic technique. Tribo-behavior performance was supported with lateral force microscopy on the surfaces of tribo-films.