Chemical and Materials Sciences: Research Findings Vol. 8

Investigation of Mechanical Behaviour of Tungsten and Magnesium Particle Reinforced Al6063 Metal Matrix Composites

P. Umar Ahamed, M. Vinoth Kumar, C. Raja, M. Manikandan — Tue, 16 Jun 2026 00:00:00 +0000

The growing demand for lightweight, high-strength materials in automotive and aerospace applications has driven research into aluminium-based metal matrix composites. This study investigates the mechanical behaviour of AL6063 aluminium alloy reinforced with tungsten carbide (WC) and magnesium (Mg) particles. Hybrid metal matrix composites were fabricated using crucible casting — one with 2.5% WC and the other with 5%, both of which included 1% Mg. Mechanical tests such as Hardness, tensile strength, compressive strength, and impact energy were conducted. Hardness increased from 39 HRB (pure AL6063) to 47 HRB and 53 HRB for 2.5% and 5% WC composites, respectively. Similarly, ultimate tensile strength improved from 75.4 MPa to 103.15 MPa and 135.7 MPa, while compressive strength increased from 229.28 MPa to 230.78 MPa and 279.52 MPa. However, impact strength decreased from 11 J (base alloy) to 7 J and 9 J for the reinforced composites, indicating reduced toughness due to increased brittleness and particle agglomeration. Scanning Electron Microscopy (SEM) analysis confirmed relatively uniform particle distribution at lower reinforcement levels and clustering at higher WC content. The results demonstrate that the addition of WC significantly enhances strength and hardness, although with a trade-off in impact resistance, making these composites suitable for applications requiring a high strength-to-weight ratio.

Alumina and Hydroxyapatite Reinforced Glass-Ceramic Composites for Bone Filler and Dental Filler Applications

Khushi Bijalwan, Sutanu Dutta, Sumana Ghosh — Tue, 16 Jun 2026 00:00:00 +0000

Alumina and hydroxyapatite were reinforced into apatite-based glass-ceramics to prepare glass-ceramic composites. The study aims to improve the mechanical properties, bioactivity and biocompatibility of the resultant composites. Developed composites were evaluated by physical, mechanical and biological characterisations. Hardness and Young’s modulus of 40 wt.% hydroxyapatite reinforced glass-ceramic composites were 1.76±0.15 GPa and 41.44±1.12 GPa, respectively, whereas 12 wt.% alumina reinforced glass-ceramic composites showed slightly lower hardness (1.25±0.11 GPa) and Young’s modulus (16.39±0.75 GPa). Apatite was formed on the surfaces of glass-ceramics and their composites when immersed in Simulated Body Fluid (SBF) solution, thereby showing good bioactivity. In vitro cytotoxicity assessment showed non-toxicity of the glass-ceramics and their composites. Thus, the experimental studies indicated that the developed glass-ceramics and composites with good mechanical and biological properties might be used for bone filler and dental filler applications.

Rice Husk Ash in Metakaolin-Derived Geopolymer Binders

Maria Kaka Etete Enoh — Tue, 16 Jun 2026 00:00:00 +0000

Geopolymers are inorganic aluminosilicate binders produced through alkali activation of precursors such as metakaolin, fly ash, and slag using alkaline activators commonly based on sodium hydroxide and sodium silicate. Owing to their lower greenhouse gas emissions and improved durability characteristics, they are increasingly investigated as sustainable alternatives to ordinary Portland cement. Current research efforts are focused on reducing dependence on commercially manufactured activators and increasing the utilisation of biomass-derived waste materials within geopolymer systems.

Rice husk ash (RHA), a silica-rich agricultural by-product containing predominantly amorphous SiO₂, has emerged as a promising supplementary material for modifying geopolymer chemistry through both precursor substitution and activator enhancement. This chapter reviews the chemistry and functional role of RHA in metakaolin-based geopolymer systems and experimentally evaluates the combined influence of RHA incorporation and alkaline activator composition on mechanical performance.

Metakaolin was produced by calcining kaolin at 700 °C, while RHA was obtained through controlled combustion at 600 °C. The experimental programme investigated RHA incorporation levels of 0–10 wt.% and sodium silicate-to-sodium hydroxide (SS/SH) ratios ranging from 0 to 1.0 using a factorial experimental design. Compressive and flexural strengths were evaluated after ambient curing, and statistical analysis was performed using analysis of variance (ANOVA).

The results demonstrated that RHA incorporation significantly improved mechanical performance, with compressive strength increasing by approximately 41% at 10 wt.% RHA and an SS/SH ratio of 1.0. Strength development was governed by the combined effects of silica availability from RHA and soluble silicate concentration within the activator system.

Overall, the findings demonstrate that RHA can serve as an effective and sustainable silica source for tailoring reaction chemistry and enhancing the performance of metakaolin-based geopolymer binders while simultaneously promoting agricultural waste valorisation.