Toughness enhancement of zirconia-toughened alumina ceramic composite using multi-phasic additives and microwave heat treatment

Aluminium oxide is a chemical compound, also known as alumina (Al2O3), is being widely used as a material in a cutting tool due to its superior mechanical properties. Nevertheless, alumina is not a straightforward solution for practical application due to its brittle nature. One of the solutions was to integrate other components into the base material of alumina. For an example, adding zirconia (ZrO2) in alumina (Al2O3) matrix produced a ceramic that improved the toughness of the material, though the toughness can be further improved. As a solution, the present work aims to enhance the ZTA ceramic composite’s fracture toughness by introducing a combination of microwave heat treatment and multi-phasic additives. Part 1 and Part 2 of this study utilised a conventional sintering process operating at a temperature of 1600°C for a total of 1 hour dwelling time. In the case of Part 3, 2.45 GHz microwave is used for sintering process at a temperature range of 1200°C - 1400°C in a 10-minutes dwelling time. The first phase of this work reported an enhanced ZTA properties with an addition of 3.0 wt.% TiO2. Moreover, the hardness is improved from 1516.13 HV/14.87 GPa (0 wt.% TiO2) to 1615.8 HV/15.85 GPa (3.0 wt.% TiO2), while the fracture toughness is improved from 5.93 MPa.m1/2 (0 wt.% TiO2) to 6.56 MPa.m1/2 (3.0 wt.% TiO2). Additionally, the enhanced mechanical properties can also be attributed to the presence of TiO2 as a vital sintering aid, which impeded Al2O3 grain growth, and consequently led to the formation of a denser and finer microstructure. In the second part, Cr2O3 is introduced as a new additive material that can be used with ZTA-3.0 wt.% TiO2. The outcome revealed that the properties associated with ZTA–3.0 wt.% TiO2 ceramic composite improved after the addition of 0.6 wt.% Cr2O3. Subsequently, the fracture toughness (7.15 MPa.m1/2) improved due to the formation of an isovalent solid solution between Al2O3 and Cr2O3. On the other hand, the enhanced hardness (1681 HV/16.5 GPa) is associated with the grain growth inhibition of Al2O3. Lastly, the microwave sintering process is used to produce ZTA-3.0 wt.% TiO2-0.6 wt.% Cr2O3 to enhance the microstructure and its properties. The outcome of the process exhibited that increased hardness (1803.4 HV/17.7 GPa) and excellent fracture toughness (9.61 MPa.m1/2) are obtained when the sample was sintered at a temperature of 1350°C within a 10-minutes dwelling time. The finding can be attributed to the process of volumetric heating, which led to shorter sintering time and lower sintering temperature. Thus, it produced tool material that has better densification, finer grain size, and excellent mechanical properties

A promising route of magnetic based materials for removal of cadmium and methylene blue from waste water

Adsorption equilibrium is an essential measure to be controlled in attaining the maximum capacity of an adsorbent. Synthesis of magnetic biochar by using various discarded biomass possesses varied adsorbate adsorption capability. Maximising the removal percentage of the pollutant from wastewater by altering operational parameters are the very important skill to be mastered by environmentalist. In this research work, mangosteen peel derived ferric oxide magnetic biochar was pyrolysed at 800 �C for 20 min via modified muffle furnace at zero oxygen environment. The factors affecting adsorption were studied for two different liquid pollutant. A comparative study was carried out for adsorption of methylene blue dye and Cd (II) ions by altering the adsorbate pH, agitation speed, and contact time and particle diffusion mechanism were investigated respectively. The removal of methylene blue dye attained maximum removal at pH of 7.0 and above, 50 min contact time and 150 rpm agitation speed. Moreover, adsorption equilibrium of Cd (II) ions reaches maximum removal percentage at the pH value of 8.0, agitation speed of 150 rpm and 60 min contact time. The thermodynamics study was performed to further understand the effect of operating temperature in determining the adsorption spontaneous of adsorption medium. The experimental analysis reveals that the produced magnetic biochar is viable for adsorption of both heavy metal ions and organic pollutant at optimised conditio

Facile and green preparation of magnetite/zeolite nanocomposites for energy application in a single-step procedure

This paper presents a green, facile and rapid method to prepare magnetite/zeolite-nanocomposites (NCs) in one step procedure at ambient temperature. The powder X-ray diffraction (PXRD) pattern of iron oxide nanoparticles (NPs) with the sole zeolite showed the broadening of zeolite peaks attributed to the incorporation of Fe3O4. Field-emission scanning electron microscopy (FESEM) analysis depicted that the Fe3O4‒NPs were formed on the surface of porous zeolite framework. Transmission electron microscopy (TEM) analysis displayed the Fe3O4 nanoparticles (NPs) were mostly in spherical shape with a mean diameter and standard deviation of 2.40 ± 0.41 nm. The selected-area electron diffraction (SAED) pattern confirmed the presence of cubic Fe3O4 phase. The vibrating sample magnetometer (VSM) results indicated the as-synthesized sample has a saturation magnetization of around 6.52 emu g−1. The magnetite/zeolite-NCs can be considered as a low-cost alternative catalyst for oxygen reduction reaction (ORR) process. The electrochemical measurement showed that the performance of magnetite/zeolite-NCs towards the ORR increased as the scan rate increased from 20 mV s−1 to 500 mV s−1. The ORR is a diffusion-controlled process in the alkaline medium

Analysis on physiochemical properties of cellulose fiber from rice straw waste

Green biobased polymeric membranes are being increasingly studied for different applications. In this study, freeze dried cellulose fiber with 35% yield was isolated from rice straw. The cellulose fiber was obtained through bleaching and delignification of the rice straw waste using soxhlet instrument and facile method of alkali treatment, respectively. The cellulose fiber was analysed through X-ray powder diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), zeta potential analyzer and scanning electron microscope (SEM). Compared to the straw, all physicochemical properties of treated cellulose fiber increased with zeta potential up to-33.61 mV. FTIR revealed that the treatments on the straw was successful to obtain cellulose fiber with high purity. In addition, the morphological study illustrated cellulose fiber with organized structure

Carbon-based Nanomaterials for Energy Storage and Sensing Applications

This chapter reviews carbon-based nanomaterials and their potential applications in energy storage and sensing. Several methods of synthesizing carbon nanomaterials have been developed over the years. They include exfoliation, thermal decomposition, chemical vapor deposition, chemical-based techniques (including Hummer’s method), laser abrasion, and arc-discharge method. There are several synthesis methods developed over the years for carbon nanomaterials. There are mainly three different approaches to the chemical vapor deposition (CVD) technique, namely, atmospheric pressure CVD, low pressure CVD, and plasma enhanced CVD (e.g., microwave plasma enhanced CVD). Chemical-based techniques are the chemical extraction of graphene films from graphite, unlike the liquid phase exfoliation technique. Laser ablation relies on the laser exfoliation or ablation of amorphous graphite, and is sometimes called pulsed laser deposition. In the field of materials science, electrochemical energy storage has become a big challenge due to the rising need for portable electronic devices and systems

Magnetically modified sugarcane bagasse biochar as cadmium removal agent in water

Heavy metals are hazardous to health at certain levels. Currently, heavy metals are removed by physicochemical treatments, such as adsorption, flotation, and electrochemical deposition, and also biological treatments, such as algal biofilm reactor and anaerobic ammonium oxidation. In this study, magnetic biochar was produced to enhance the effectiveness and performance of the adsorbent for heavy metal removal. This study aimed to synthesise high-performance magnetic biochar, to determine the optimum parameters and conditions for high yield of magnetic biochar and high removal of cadmium (Cd2+) from aqueous solution, and to determine the adsorption kinetics and isotherms for Cd2+ removal. Nickel oxide (NiO)-impregnated sugarcane bagasse was subjected to slow pyrolysis to produce magnetic biochar. The impregnated metal, pyrolysis temperature, and pyrolysis time were varied to determine the optimum parameters and conditions to produce high-performance magnetic biochar. The removal of Cd2+ from aqueous solution and batch adsorption study were conducted. The synthesised magnetic biochar was characterised using field-emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, Fourier transform infrared (FTIR), and vibrating sample magnetometer (VSM). The adsorption data agreed well with the pseudo-second-order model and followed the Langmuir isotherm model. This study achieved 88.47% removal efficiency of Cd2+ from aqueous solution. Thus, the removal of this heavy metal as a human carcinogen reduces the hazardous effects on human health and reduces the toxicity in the environment

The effects of CeO2 addition on the physical and microstructural properties of ZTA-TiO2 ceramics composite

The effect of CeO2 addition ranging from 0 wt. % to 7 wt. % on phase, microstructural evolution, physical and mechanical properties of ZTA-3 wt. % TiO2 ceramic composite were investigated. The samples were prepared by solid-state mixing and sintered at 1600 °C for 1hr under pressureless condition. Samples were then characterized by XRD, SEM, densitometer and Vickers indentation method. Based on XRD analysis, m-ZrO2 began to diminish at 1 wt.% CeO2 while secondary phases, i.e. Ce0.7Zr0.3O2and Zr0.4Ti0.6O2 initiated at 3 wt.% CeO2 addition. SEM images showed finer grain sizes was produced upon increasing amount of CeO2 up to 5 wt.%, corresponding to higher average grain intercept (AGI) values. From the results obtained, the optimum amount of CeO2 addition was at 5 wt. % which yielded the highest bulk density (4.41 g/cm3), firing shrinkage (21.94%), hardness (1580.10HV) and fracture toughness (9.77 MPa m1/2). This is contributed by the grain refinement and the highest amount of secondary phases formed, especially Zr0.4Ti0.6O2. However, with an excessive addition of CeO2, i.e more than 5 wt.%, grain sizes enlarged and the amount of secondary phases reduced, which degraded the mechanical properties of ZTA-3 wt. % TiO2

Single-route synthesis of binary metal oxide loaded coconut shell and watermelon rind biochar: Characterizations and cyclic voltammetry analysis

Generally, the type of biomass precursors is one of the key factors affecting the properties of synthesized biochar. This novel study therefore examined the single-route preparation of coconut shell and watermelon rind biochar with the combination of two types of binary metal oxide, iron nickel oxide (Fe2NiO4), and cobalt iron oxide (CoFe2O4) by employing a novel vacuum condition in an electric muffle furnace. The samples were characterized by several methods such as Fourier transform infrared (FTIR), field emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) Surface Area. The optimum pyrolysis temperature for producing a high surface area of 322.142 m2/g and 441.021 m2/g for coconut shell biochar and watermelon rind biochar, respectively, was recorded at 600 °C. FTIR analysis revealed lesser adsorption bands found in FTIR spectrum of the samples with higher pyrolysis temperature (500–700 °C). In addition, FESEM results also revealed the surface changes of the samples with the impregnation of CoFe2O44 and Fe2NiO4. Furthermore, the value added application of biochar in electrochemical energy storage has been explored in the present work. In typical three-electrode configuration, WR-BMO 600 exhibits about 152.09 Fg−1 with energy density about 19.01 Wh kg−1

Performance and emissions of diesel engine with circulation nonsurfactant emulsion fuel system

Diesel engine is known for its durable operation and capability of utilizing various type of fuels, however, dangerous exhaust emissions are emitted from diesel engines. Nonsurfactant emulsion fuel is a potential fuel for diesel engine to reduce for Nitrogen oxides (NOx) and Particulate matter (PM) emission compare to conventional diesel fuel in a diesel engine. In this study, emulsion fuel was prepared using a mixer known as Circulation Non-Surfactant Emulsion Fuel System. The study carried out with different water percentages in the emulsion fuel given as follows: 3%, 6%, and 9% and at a different engine load condition from 1-4 kW with a constant speed of 3200 rpm. Results show that, 6% emulsion fuel shows average 4.38% reduction in NOx emission and 1.10% reduction in fuel consumption. 9% emulsion fuel show higher amount of CO emission compare to Diesel while it reduces CO2 emission. Overall, 6% when prepared are recommended for the formation of non-surfactant emulsion fuel