Annamalai Gnanavelbabu

The fabrication of aluminum metal matrix composites (AMMCs) plays a pivotal role in determining their suitability for marine applications, where materials are subjected to harsh environments, including saltwater exposure, high humidity, and fluctuating mechanical loads. Poor particle dispersion, agglomeration, and inadequate bonding between the matrix and reinforcements often result in localized corrosion, reduced wear resistance, and structural degradation, making conventional AMMCs less reliable in marine settings. The presence of defects such as porosity and uneven reinforcement distribution further compromises their mechanical integrity and long-term durability under corrosive marine conditions. To overcome these challenges, this study employed an innovative stir-ultrasonication-squeeze (SUS) casting technique to enhance the microstructural and corrosion properties of AA2014-nAl ₂ O ₃ nanocomposites. Critical process parameters, including ultrasonic power (2250 W), ultrasonication time (16 minutes), pouring temperature (700 °C), squeeze pressure (150 MPa), and reinforcement content (2 wt.%), were systematically optimized to achieve uniform particle dispersion, grain refinement, and enhanced corrosion resistance. Advanced characterization using high-resolution scanning electron microscopy (HR-SEM) and optical microscopy (OM) revealed the mitigation of particle clustering and a refined grain structure with a minimum size of 43 µm under optimized conditions. Taguchi grey relational analysis (TGRSA) identified the influence of process parameters on corrosion performance, with ANOVA showing ultrasonication time as the most significant factor (11.5% contribution). Confirmation tests demonstrated optimal process conditions—2.248 kW ultrasonic power, 15.89 minutes ultrasonication time, 700.1 °C pouring temperature, 143 MPa squeeze pressure, and 1.95 wt.% reinforcement—leading to significant improvements in corrosion resistance, including a 14% reduction in salt spray corrosion rate and a 37% increase in grey relational grade (GRG). These findings underscore the potential of the SUS casting technique to address the traditional limitations of AMMCs, providing a pathway for developing corrosion-resistant materials tailored for marine and other extreme environmental applications.

AZ91D composites are ideal for weight-sensitive, high-stress aerospace applications because of their improved mechanical properties and corrosion resistance. This study focuses on the microstructural, physical, and mechanical characterization of newly developed AZ91D composites reinforced with Zirconium diboride (ZrB₂) and explores their optimal performance in tribocorrosion conditions. The metal matrix composites (MMCs) were fabricated using the stir-ultrasonication-squeeze (SUS) casting technique. Additionally, an innovative approach called entropy-integrated TODIM, an MCDM method, was employed to determine the optimal process conditions. Based on the TODIM results, the optimized tribocorrosion parameters were found to be a wt.% reinforcement of 15%, an ageing temperature of 230 °C, an applied load of 30 N, and a pH value of 10. Furthermore, the desirability approach showed significant deviations in responses. Using the desirability approach and optimizing process parameters minimized corrosion pits and peak generation in the surface profile.

The modern era has realized the tremendous potential of metal matrix composites (MMCs) in slowly substituting the traditional materials used in automotive and aerospace industries. Traditional machining of second generation MMCs is quite challenging due to heat generation, tool wear, and low cut surface quality. This work presents an analysis on hydro-abrasive machining (HAM) of the Al6061/Al2O3/B4C composite by using an amalgamated method of gray incidence based response surfaces (GIRS) to produce a good surface quality. The influence of HAM variables [abrasive flow rate (FA), waterjet pressure (PWJ), jet traverse speed (SJT), and stand-off distance (DS)] on various cut surface characteristics [surface roughness (Ra), striation-free zone (SFZ), striation angle (ΘS), and kerf angle (ΘK)] is examined using L27 OA and response surface plots. A hybrid approach of the GIRS method is presented for necessary polynomial modeling and simultaneous optimization. The reduction of response values is primarily influenced by the waterjet pressure and jet traverse speed. An optimal cutting condition resulted in a significant reduction in surface roughness by 19.22% and striation angle by 10.82%. The improvements in striation-free zone and kerf angle were also notable with reductions of 7.89% and 4.74%, respectively. FESEM images of machined surfaces, profile graphs of surface roughness, and images observed using atomic force microscopy were also studied.

In recent decades, there has been a notable advancement in the field of bioactive, biodegradable, and biocompatible metallic materials, particularly for applications in general surgery. Among these materials, magnesium alloy-based composites have gained popularity due to their excellent biological properties and adequate strength. However, their resistance to wear is still an area that requires further investigation. Therefore, this study examines the wear properties of stir-ultrasonic-squeeze-casted magnesium (AZ91D) composites, incorporating distinct nanoparticles such as ZnO, MnO, and TiO₂. The Evaluation-based Distance from Average Solution (EDAS) approach is used to determine the optimal parameters. Additionally, an Analysis of Variance (ANOVA) is conducted to identify the crucial factors influencing the responses. The effect of process factors on the wear rate and Coefficient of Friction (COF) is then investigated using response surface plots. The confirmation assessments reveal that the optimal parameter conditions for the tribo process comprise a 50.0018 N applied load, a 1.4998 m/s sliding velocity, and the AZ91D + 1% TiO₂ (ATO) composite utilization. The ANOVA findings demonstrate that the applied load significantly contributes to 67.3% of the wear performance. Subsequently, after determining the optimal condition, it is observed that the ATO composite, when exposed to temperatures above 150 °C, exhibits an abrupt increase in wear rate and COF due to the degradation of grain strength and the dissolution of the β-phase within the composite.