In this present study, synthetic tobermorites are prepared using bio-waste (snail shell) and municipal waste (container glasses) as lime and silica precursors respectively. Six batch compositions ...were formulated with varying combination of soda-lime glass and snail shell ash. The bodies were sintered at 950°C for a holding period of 2h in an electric muffle furnace. Analyses such as scanning electron microscopy (SEM/EDS), Fourier Transform Infra-red Spectroscopy (FT-IR), X-ray diffractometry (XRD) were used to assess the microstructure, functional groups and the phase composition of the prepared tobermorites respectively. The results of the morphology shows that the tobermorites possess irregular but spherical shaped grain with coated water films while the EDS shows the presence of Ca and Si with small amount of Al confirming tobermorite. The FT-IR indicates Ca–O–Si and Si–O–Si as main functional groups while the phase composition investigated by XRD indicate low intensity peaks of calcium silicate (CaSiO3).
En este estudio, las tobermoritas sintéticas se preparan utilizando biorresiduos (caparazón de caracol) y residuos municipales (vasos de contenedores) como precursores de cal y sílice, respectivamente. Se formularon seis composiciones discontinuas con una combinación variable de vidrio de cal sodada y ceniza de concha de caracol. Los cuerpos se sinterizaron a 950°C durante un período de retención de 2 h en un horno de mufla eléctrico. Se utilizaron análisis como microscopía electrónica de barrido (SEM/EDS), espectroscopía infrarroja por transformada de Fourier (FT-IR), difractometría de rayos X (XRD) para evaluar la microestructura, los grupos funcionales y la composición de fase de las tobermoritas preparadas, respectivamente. Los resultados de la morfología muestran que las tobermoritas poseen un grano irregular pero esférico con películas de agua recubiertas, mientras que el EDS muestra la presencia de Ca y Si con una pequeña cantidad de Al que confirma la tobermorita. El FT-IR indica Ca-O-Si y Si-O-Si como grupos funcionales principales, mientras que la composición de fase investigada por XRD indica picos de baja intensidad de silicato de calcio (CaSiO3).
In recent years, the quest to improve sustainability and cut costs has shifted focus to the use of waste materials as reinforcement in metal matrix composites. The current study aimed to evaluate the ...effects of valoxy as an alternative material to alumina on Al-6063 based composites for the first time. Al-composites containing 10 wt-.% Al2O3: Valoxy in the steps of 0, 10:0, 7.5:2.5, 5:5, 2.5:7.5, and 0:10 were fabricated using a double stir casting approach, while representative samples from each composition were studied for microstructure, mechanical, and wear properties, respectively. The results of the chemical composition showed that valoxy contains 70 wt-.% Al2O3 alongside other oxides like SiO2 and MgO, making it a potential sustainable alternative to traditional alumina. The density of the composites decreases with an increase in valoxy content, which is attributed to the density of valoxy (1.4 g/cm3) compared to alumina (3.89 g/cm3), which it replaces. There is also a general improvement in all the properties tested across the composites containing valoxy compared with the base alloy and Al-6063/Al2O3 samples. Composite samples 7.5:2.5 and 5:5 (Al2O3:Valoxy) showed consistent results with better hardness of 46.45 and 46.21 HB, tensile strength of 209.2 and 184.8 MPa, and fracture toughness of 6.54 and 4.67 MPa m1/2, respectively.
This research attempts to evaluate the effects of age-hardening on the mechanical behavior of aluminum (6063) alloy reinforced with alumina (Al2O3) particles. Aluminum (6063)/Al2O3 composites ...containing 0, 5, 7, 9 and 10 wt% Al2O3 particles respectively were fabricated using double stir casting technique and representative samples from each composition were subjected to age-hardening treatment at 180 °C for 60 min, 120 min and 180 min respectively. The microstructures were evaluated using SEM while fracture toughness and tensile properties were used to evaluate the mechanical behavior of both the as-cast composites and their age-hardened counterparts. The microstructure evaluation reveals formation of coherent precipitates of Mg2Si evenly distributed in the age-hardened composites. Significant improvement in tensile strength values of 129.8, 88.6, 90.6, 137.9 and 170.6 MPa were obtained for the age-hardened composites compared to their as-cast composites with 42.2, 72.9, 81.2, 80.84 and 71.5 MPa across the series respectively. Similar trend was observed for fracture toughness with KIC values of 7.5, 5.8, 4.5, 7.8 and 9.6 MPam1/2 for age-hardened composites compared with 4.68, 4.64, 4.07, 4.06 and 3.59 MPam1/2 obtained for their as-cast composites. Age-hardening time of 180 min impart better tensile strength and fracture toughness.
This research aims at investigating the influence of quarry dust (QD)-silicon carbide (SiCp) particles weight percentage on the mechanical properties and wear behavior of ZA-27 alloy based hybrid ...composites. The ZA-27 alloy hybrid composites containing 8wt% and 10wt% QD-SiCp with varied weight percentage of 0, 25, 50, 75 and 100% quarry dust respectively was produced using stir casting technique. Microstructural evaluation, density measurement, estimated percentage porosity, mechanical properties evaluation and wear evaluation were used to assess the performance of the produced composites. The results show that the microstructures of the produced composites are similar, displaying a somewhat feathery feature which is the dendritic structure of the ZA-27 alloy matrix with homogeneous dispersion of the reinforcing particles. The density of the composites decreased with increase in the weight percent of quarry dust (corresponding to decrease in weight percent of SiCp) while slight voids exist as compared to the unreinforced alloy. The hardness and tensile properties of the composites improved showing similar trend as quarry dust increases to maximum addition of 75% for both the 8 and 10wt% composites grade; there is consistent increase in fracture toughness with exception of composites containing 50% stone dust which showed slight decrease in both the 8 and 10wt% composites grade while superior wear behavior in terms of wear loss was observed for hybrid composites over the unreinforced and SiCp single reinforced alloys for both 8 and 10wt% composite grades.
This paper investigates the corrosion behaviour of Zn-27Al based hybrid composites reinforced with quarry dust (QD) and silicon carbide particles (SiCp). The Zn-27Al hybrid composites containing 8 ...wt% and 10 wt% SiCp-QD particles reinforcement with varied weight percentage of 0, 25, 50, 75 and 100% quarry dust respectively were synthesized using stir casting technique. The corrosion behaviour of the composites was investigated in 0.3M H2SO4 and 3.5 wt% NaCl solution at 25ºC using electrochemical methods in accordance with ASTM G59-97(2014) standard. The results show that for 8 wt% reinforcement, the hybrid composites A2 and A3 (corresponding to 50% SiCp: 50% QD and 25% SiCp: 75% QD respectively) having corrosion rate of 0.006 mmpy displayed superior corrosion resistance. For 10 wt% reinforcement, hybrid grades B1 (75% SiCp: 25% QD), B2 (50% SiCp: 50% QD) and B3 (25% SiCp: 75% QD) has superior corrosion rate of 0.0172, 0.0126 and 0.0135 mmpy respectively while B4 (corresponding to 100% QD) shows the most superior corrosion rate of 0.00315 mmpy when compared with the monolithic alloy having corrosion rate of 0.213 mmpy all in marine environment (3.5 wt% NaCl solution). However, except for composite grade A2 with 0.055 mmpy corrosion rate and B4 (corresponding to 100% QD) with superior corrosion rate of 0.0143 mmpy in 0.3M H2SO4 medium, all other composite grades performed poorly in the acidic medium.
The use of wastes as substitute to traditional materials from non-renewable sources has recently increased as a result of growing interest in environmental preservation and solid wastes management. ...In this work, the effect of waste glasses on the physico-mechanical properties of soft porcelain is investigated. Soft porcelain bodies containing milled waste soda-lime and borosilicate glasses at varied percentage were composed and were uniaxially dry pressed under 40kN load using hydraulic pressing machine. The pressed bodies were oven dried at 110°C and were later subjected to firing at temperatures of 1000°C and 1200°C respectively. Tests such as water absorption, porosity, bulk density and firing shrinkage were used for physical characterization while flexural strength and wear loss was used for mechanical characterization under standard approach to investigate the behavior of the developed soft porcelain bodies at temperatures of 1000°C and 1200°C respectively. The results showed that higher densification was observed at 1200°C while water absorption drastically reduced below the required maximum 1% and porosity fall below 4% for both samples containing waste soda-lime and borosilicate glasses respectively. Improvements in terms of wear loss and strength properties were also observed for samples containing waste soda-lime and borosilicate glasses respectively subjected to temperature of 1200°C. This better behavior observed at temperature of 1200°C can be attributed to better glassy phase formation and mullite growth at that temperature.
El uso de desechos como sustitutos de los materiales tradicionales de fuentes no renovables ha aumentado recientemente como resultado del creciente interés en la preservación del medio ambiente y el tratamiento de desechos sólidos. En este artículo se analiza el efecto de los vidrios de desecho en las propiedades físico-mecánicas de la porcelana blanda. Los cuerpos de porcelana blanda que contenían residuos molidos de vidrio cálico-sódico y vidrio borosilicatado en un porcentaje variable se compusieron y se prensaron uniaxialmente en seco bajo una carga de 40kN con una máquina de prensado hidráulico. Los cuerpos prensados se secaron al horno a 110°C y luego se sometieron a cocción a temperaturas de 1.000 y 1.200°C, respectivamente. Se utilizaron pruebas como absorción de agua, porosidad, densidad de masa y contracción por cocción para la caracterización física mientras que la resistencia a la flexión y la pérdida por desgaste se utilizaron para la caracterización mecánica con un enfoque estándar para analizar el comportamiento de los cuerpos de porcelana blanda elaborados a temperaturas de 1.000 y 1.200°C, respectivamente. Los resultados mostraron que se observó mayor densificación a 1.200°C mientras que la absorción de agua se redujo drásticamente por debajo del máximo requerido del 1% y la porosidad cayó por debajo del 4% en ambas muestras que contenían residuos de vidrio cálico-sódico y vidrio borosilicatado, respectivamente. También se observaron mejoras en términos de pérdida por desgaste y propiedades de resistencia en muestras que contenían residuos de vidrio de soda-lima y borosilicato, respectivamente, sometidas a una temperatura de 1.200°C. Este mejor comportamiento, que se observó a una temperatura de 1.200°C, puede atribuirse a una mejor formación de fase vítrea y crecimiento de mullita a esa temperatura.
In this work, nano-sized silica xerogel particles were synthesized using sodium silicate solution prepared from waste container glasses (of mix colors) as precursor. The as-received waste container ...glasses of different mix colors (green, white and amber) from municipal dumpsite were initially washed, crushed and wet milled for 24 h then sieved through 63 μm mesh. The sieved glass slurries were then oven dried at 110 °C for 72 h to obtain powdered glass (GP). Appropriate amount of GP was reacted with 320 ml of 3 M NaOH solutions respectively in a 500 ml Erlenmeyer flask placed on a hot plate connected with a reflux condenser and continuously stirred at 40 rpm with the aid of magnetic stirrer for a period of 3 h under reaction temperature of 200 °C. The resultant solution was filtered to obtain sodium silicate solutions (SSS). 3 M HCl was prepared and was gently added into the SSS whilst continuously stirred to obtain a white gelly-like mixture (at pH ˂10). The gelly mixture was left for 18 h (ageing), then filtered and dried in an electric oven at 80 °C for 12 h to obtain highly pure silica gel particles and then characterized. The results showed that the synthesized nano-sized silica particles range between 0.031 (31 nm) μm to 0.051 (51 nm) μm.
•Recycling of wastes instead of allowing them to constitute environmental nuisance.•Practice green chemistry approach of no toxic by-products released to environment.•Brings innovation of the possibility of harnessing silica rich wastes and turning them into new and useful products.•Silica xerogel nanoparticles can be synthesized from waste glasses.
This work presents a novel approach for the fabrication and characterization of 45S5 bioglass-ceramics using rice husk ash (RHA) and eggshell ash (EGSA) as alternative resources at varying ...inclusions. In this study, RHA and EGSA, which are abundant agricultural waste products, are utilized to synthesize 45S5 bioglass through a microwave energy-assisted melt-quenching approach and sintered at temperatures of 950, 1000 and 1050 °C respectively. The obtained bioglass-ceramics (BGCs) were characterized for their structure, mechanical properties, morphology, antibacterial properties, and bioactivity. The results showed the developed BGCs exhibited a broad hump base with sharp crystalline peaks. The morphology showed irregular morphology containing heterogeneous grains, rough and porous surface respectively, essential for bone in-growth and cell infiltration, while a cauliflower-like appearance of carbonate-hydroxyapatite was well pronounced on all the samples after immersion in simulated body fluid. The developed BGCs also showed improved mechanical properties with increased sintering temperature and antibacterial properties to justify their use for biomedical applications.
Glass foams are modern developed building materials which are now favorably competing with conventional materials for applications in thermal insulation. In this study, glass foams are synthesized ...solely from waste container glasses of mixed colors using sodium silicate (water glass) as foaming agent. Several glass foams of 150 × 150 × 30 mm were prepared from waste glasses of 75 μm, 150 μm and 250 μm size with addition of 15 wt % sodium silicate respectively and pressed uniaxially under a pressure of 10 MPa. The prepared glass foams were then sintered at temperatures of 800 °C and 850 °C respectively. Tests such as bulk density, estimated porosity, flexural strength, compressive strength and microstructure evaluation were used to assess the performance of the developed glass foams. The results showed that with increasing temperature and grain sizes, the percent porosity of the developed foams increased while the bulk density decreased. The microstructure evaluation showed that the finer the grain sizes used, the more homogenized are the pores formed and the higher the temperature, the larger the pores but are mostly closed. Both compressive and flexural strength were found to decrease with grain sizes and higher temperatures. The thermal conductivities of all the developed foam glasses satisfy the standard requirement to be used as an insulating material as their thermal conductivities did not exceed 0.25 W/m.K.
During the past few decades, zinc-aluminum family of alloys has increasingly been used as a result of the good combinations of their mechanical, physical, tribological, and low production costs. ...However, among the zinc-aluminum family, ZA-27 alloy has the highest strength, low density, excellent bearings, and wear properties. In order to improve these good properties possessed by this alloy, ZA-27-based composites became a new generation of metal matrix composites that possess the potentials of meeting the recent needs of advanced engineering in bearing and bushing applications. The optimum display of behaviors of this material is a function of the processing parameters and reinforcing phases. This review article attempts to review the recent developments on synthesis, combination of reinforcing materials used in processing of ZA-27-matrix-based composites and how it influences the microstructure, mechanical, and corrosion behavior of the composites. This review also summarizes previous works done by several researchers on ZA-27-based composites in achieving optimum mechanical and wear performance in these composites.
PDF
