Getinet Asrat Mengesha

Mullite ceramics were synthesized from filter cake waste following the diphasic gel method. Filter cake waste, with over 65% silica content, and aluminum nitrate nonahydrate were utilized as the sources of silica and alumina, respectively. The prepared samples were sintered at various temperatures of 1150, 1250, and 1350 °C. The sintered bodies were then evaluated for porosity, density, compressive strength, and dielectric strength. Differential Thermal Analysis (DTA) revealed exothermic peaks at 970 °C and 1147 °C, corresponding to spinel and mullite formation, which was also confirmed by X-ray diffraction (XRD) analysis. The XRD result also showed single-phase mullite crystallization at 1250 °C. Field Emission-Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS) demonstrated morphological changes, grain growth, and uniform elemental distribution in sintered mullite ceramics. The mullite ceramics sintered at 1350 °C exhibited a density of 2.615 g/cm³, compressive strength of 420 MPa, and dielectric strength of 10.2 kV/mm. These findings highlight the potential of the diphasic gel method to produce high-quality mullite ceramics from industrial waste, contributing to cost-effective, eco-friendly materials with promising applications, including electronic devices, electrical power transmission systems, and other structural and functional advanced ceramics.

Biocomposite materials have brought other possibilities to the manufacturing industry rather than synthetic materials. Biodegradable polymer materials such as polylactic acid (PLA) have attracted various industries’ attention for numerous applications due to their tensile strength (TS), while they have some mechanical weaknesses that prevent them from being utilized for different engineering applications. The amalgamation of microcrystalline cellulose (MCC) at varying percentages (0%, 3%, 6%, and 9%) and montmorillonite (MTT) at the same percentages (0%, 3%, 6%, and 9%) serves as a filler, while sorbitol (S) is used as a plasticizer in concentrations of 10%, 20%, 30%, and 40%. The material is fabricated at different temperatures (Ts) of 100°C, 125°C, 150°C, and 175°C using the melt‐mixing method, and the process is optimized to establish an effective experimental setup. This study prepared 16 samples through Taguchi’s orthogonal array design. The optimal factor level combinations were investigated for flexural strength (FS) at (3% MCC/9% MTT/20% S/175°C); at these levels FS is 96.5 MPa; flexural modulus (FM) at (6% MCC/9% MTT/20% S/175°C); at these control factors FS is 9.8 GPa; TS at (9% MCC/9% MTT/10% S/175°C); at these levels TS is 85.2 MPa; Young’s modulus (YM) at (6% MCC/9% MTT/0% S/150°C); at this experimental run YM is 4.22 GPa; hardness value (HV) at (6% MCC/9% MTT/10% S/175°C); at these levels HV is 138.2; impact strength (IS) at (9% MCC/9% MTT/20% S/175°C); at these factor combinations IS is 54.2 J/m; water absorption (WA) at (0% MCC/0% MTT/0% S/150°C); at this experimental run WA is 2.42%; and density (D) at (9% MCC/9% MTT/30% S/175°C) at this experimental run density is 0.0427 g/mm ³ . Analysis of variance (ANOVA) for the regression model shows the statistical significance of the model and the significance of the factors. The comparison analysis indicated that the quality characteristics of the optimum MCC/MTT/S/PLA material are comparable to the performances of various engineering materials.

Hybrid Titanium Metal Matrix Composites (HTMMCs) has material that exhibits a lower wear rate compared to other materials, particularly in specific various applications. The primary objective of this study is to examine the impact of reinforcements incorporating with different weight fractions of Boron Carbide, Molybdenum Dioxide, Silicon Carbide, and Zirconium Oxide on the mechanical, metallurgical, and physical characteristics of titanium grade 5 composites synthesized through powder metallurgy (PM). Milling time for mixed nanoparticles was 1, 2, 3, 4, 5, and 6 h, and milled powders were compressed at 65 MPa pressure for 50 min. Green compacted samples were sintered at temperatures ranging from 900°C to 1150°C for durations of 1, 2, 3, 4, 5, and 6 h. Furthermore, an investigation was carried out to analyze the morphology and XRD in order to assess the dispersion and interfacial bonding between the reinforcements and matrix. The result of this investigation shows that the minimum porosity of the developed composite is 0.015% and the mechanical tests demonstrated a significant enhancement, with a maximum hardness of 60.9HRC reached compared to 36HRC; maximum compressive strength of 2730 MPa reached compared to 970 MPa and a minimum specific wear rate of 0.013 × 10 ⁻³ gm/m reached compared to 0.01 mm ³ /m for the base alloy.

The globally increasing concern over industrial byproducts highlights the need for sustainable waste management solutions. Repurposing such byproducts offers a promising approach to sustaining development. This study focuses on the extraction of silica from filter cake waste (FCW). Amorphous silica was successfully synthesized through sol–gel method using acetic acid as the precipitation agent. XRD and SEM analyses were used to confirm the crystal structure of silica to be amorphous, while FTIR studies identified characteristic Si−O−Si bonds, indicating high purity of the extract. The silica purity was further validated by EDS analysis to be about 98.98%. Optimization of the extraction process was carried through variation of parameters such as NaOH concentration, temperature, and stirring time, resulting in a maximum yield of 54%.

Natural fiber composites offer a range of advantages, from biodegradability after the component’s lifespan little to no output of greenhouse gases and reduced pollution. These properties have made natural fiber composites popular in military, automotive, aerospace, and residential spaces. Bamboo Stem Ash Powder (BSAP) is one example of a commonly found natural fiber composite. This research looks into its effect on the physical and mechanical parameters when added to pure aluminum. The 0, 2.5, 5, 7.5, and 10 weight percent of BSAP were added in addition to the secondary reinforcements in the matrix. Parameters such as density, porosity, hardness, compressive strength, X-Ray Diffraction analysis results of BSAP/composite mixture, as well as Thermal Gravimetric Analysis (TGA) findings for the BSAP itself were all studied. The highest values of hardness 239.66 HV and compressive strength 308.32 MPa have been observed with 7.5 weight percent BSAP addition. It can be confirmed that these natural fiber composites can improve standard materials’ behavior when used correctly and can be potential candidates for many engineering applications.

Sustainability of energy supply has become a prime concern for energy producers and consumers alike. There is heightened awareness in the global community about the decreasing supply of conventional fossil fuels along with increasing fuel and energy demand and the consequent rise in unit energy cost. In addition to the sustainability aspect, the environmental impact of emissions from fossil fuel combustion is the focus of global targets for emissions reduction. In this context, the research and application of sustainable and non-polluting fuels become significant. Internal combustion (IC) engines are part of a significant energy-consuming sector, and the application of sustainable and non-polluting fuels within IC engines would be impactful. Biogas and hydrogen are viewed as sustainable and non-polluting alternatives to conventional fossil fuels. However, either of these used individually offer certain disadvantages. Experimental results and analysis of the performance and emissions characteristics of an IC engine fueled with biogas blended with 5, 10, and 15% hydrogen volume fractions are studied. An increase in hydrogen content increases the engine’s performance and power and reduces carbon monoxide (CO) and total hydrocarbons (THCs). However, nitrogen oxides (NOx) are found to increase due to higher combustion temperatures attributed to hydrogen. A 17.5% increase in brake power is observed for 15% hydrogen-enriched biogas, compared to plain biogas, at an equivalence ratio of 0.6. Similarly, a 17% increase in BTE, a 50% decrease in CO, a 68% decrease in UHC, but a 71% increase in NOx are observed for 15% hydrogen-enriched biogas.

The application of biomass-derived composite material is in high demand worldwide in various commercial sectors, including automotive, due to its durable, cost-effective, and environment-friendly characteristics. However, one of the limiting factors of biomass-based composites is its higher water absorption capacity compared to commercial synthetic composites. Therefore, this study aimed to optimize the water absorption capacity of biomass-based, wheat straw fiber-basalt hybrid composite brake pad using the Taguchi method by considering the particle size and volume % of the composite compositions. The composite synthesized in this study carried two variations of particle sizes of basalt, wheat straw, steel, river sand, and graphite, as well as two-volume percentages of epoxy resin for optimization. All composites were molded using a compression molding process at compressive pressure of 6 MPa for 2 h curing in a forced convection oven at 100 °C. Water absorption capacity has been determined according to ASTM D570. The wheat straw fiber has been chemically treated with 5 wt.% of sodium hydroxide (NaOH) to remove the impurities, lignin, and hemicellulose and increase the surface area of the fiber, resulting in a larger area of contact between the fiber and the matrix. Elemental analysis, crystallinity, morphology, and mechanical strength of wheat straw fiber-based composites have been determined by XRD, SEM, and compression tests, respectively. The statistical method, analysis of variance (ANOVA), was implemented for Taguchi optimization of the composite compositions. The maximum compressive strength and minimum and maximum water absorption capacity of composites were obtained as 77 MPa, 3.55%, and 26.86%, respectively. From the optimum setting of the confirmation experiment, the optimal water absorption value of 5.718% has been obtained. The optimum particle size of the composite compositions was 1 mm basalt particle, 0.5 mm wheat straw fiber, 1 mm steel particle, 1 mm river sand, 0.5 mm graphite dust particle, and 30 vol% epoxy resin by Taguchi method. The parameter impact of Taguchi ranking on water absorption capacity presented the maximum improvement of water absorption, 10.47%, with river sand particle size.

Coffee husk (CH) is a sustainable and abundantly available cellulosic waste material. Its fiber consists of cellulose as the major structural part which leads to potential utilization for the manufacturing of microcrystalline cellulose (MCC) products that can be utilized for different industrial applications. In the present study, chemical composition of outer skin-isolated coffee husk was determined and sequential treatments of various untreated (UT) sample, ethanoltoluene treated sample through dewaxed (DW) treatment, sodium hydroxide (NaOH)treated sample through alkali (AT) treatment, and sulfuric acid (H₂SO₄)treated sample through bleaching (BL) treatment have been carried out. The Micro Crystalline Cellulose (MCC) has been extracted through hydrogen peroxide (H₂O₂) after BL treatment. The BL treatment for MCC extraction process was conducted without chlorine and additional harsh acid treatment, respectively. The characterization of chemically treated samples was carried out to investigate their morphological, physico-chemistry, and thermal behavior through a scanning electron microscope (SEM), Fourier transform infraredray (FTIR), X-ray diffraction (XRD), thermo gravimetric analysis (TGA), and differential temperature analyzer (DTA). From the chemical composition analysis; the cellulose, hemicellulose, lignin, and extractive content were determined and its values were (52.9), (12.5), (24.3), and (9.4), respectively. In the morphological examination, the great untreated (UT) fiber sample was greatly reduced into a micro-sized BL sample, revealing that (from FTIR analysis) the lignin and hemicellulose contents were greatly removed during chemical treatments and the presence of a micro crystalline cellulose region with 54.7 yield. Also, the sample AT and BL showed the lowest amorphous region in X-RD due to the removal of hemicellulose and lignin. The highest crystallinity index has been determined for the BL sample, i.e., 89.9. Additionally, the thermal analysis shows that the AT and BL sample has great thermal stability than other (UT and DW) samples at high temperature. Therefore, the outer skin separated coffee husk was prepared from agricultural waste was subjected to eco-friendly chemical treatments to yield MCC. Thus, the extracted MCC is expected to be reliable for replacing other plant materials for the production of crystalline nanomaterial and reinforcing constituent for the fabrication of bio composite.

Hybrid aluminum matrix composites (HAMCs) are a new class of advanced composite and hybrid materials that can be customized and engineered to achieve specific properties for specific applications in specific environments. HAMCs are popular in the transportation industry due to their reduced cost and fuel consumption as compared to conventional materials. This research article has mainly focused on multi-response optimization through an L₁₆ orthogonal array experimental design employing Taguchi-based Grey Relational Analysis. It was intended to explore the influence of tetra hybrid reinforced HAMCs synthesized using pure Al matrix with fixed wt% of primary reinforcements (5 wt% SiC and 5 wt% Al₂O₃) and varying wt% of secondary reinforcements such as (0.5, 2.5, 4.5, and 6.5) wt% of Gr and (0.5, 2.5, 4.5, and 6.5) wt% of SCBA on physicomechanical properties of HAMCs when milling time, compaction pressure, and sintering temperature were varied. The Taguchi-Grey’s relational analysis gave the optimal combination of the process and reinforcement parameters for both the physical and the mechanical properties such as milling time (5 h.), compaction pressure (55 MPa), sintering temperature (450 °C), Gr content (0.5 wt%), and SCBA content (4.5 wt%). At the optimum parameter settings, the average density, porosity, hardness, compressive strength, and ultimate tensile strength were 2.5118 gm cm⁻³, 0.8653%, 4228.45 MPa, 343.33 MPa, and 1516.41 MPa, respectively. The utilization of Taguchi and GRA methods have significantly confirmed that the influence of compaction pressure was highest among the all the other four parameters. The newly synthesized tetra hybrid reinforced HAMCs have shown superior physicomechanical properties compared to pure Al, and single as well as double reinforced HAMCs. Therefore, it is anticipated that the newly developed tetra hybrid reinforced AMC material will be utilized in heavy-duty, aerospace, medical, automotive, marine, and other applications.