Parallel evolution of microstructure and mechanical properties of bioglass/hydroxyapatite composites

The purpose of this research work is to establish the parallel evolution stages of microstructure and mechanical properties development as well as their relationship. This kind of observation is not present in the literature of this research area and studies of the relationship between microstructure and mechanical properties have been directing towards the product of final sintering temperature, largely neglecting the parallel evolution of microstructure and mechanical properties and their relationship at various selected sintering temperature. Commercial bioglass (BG) of SiO2–CaCO3–Na2O3–P2O5–CaF2were prepared by conventional melt quenching technique and mixed with hydroxyapatite (HA) via solid state reaction. To complete the evolving series of temperature, the pellet samples were subjected to sinter from 500 to 1000°C with 50°C increments. Sintered sample were characterized by Differential Scanning Calorimetry (DSC), X-ray Diffractometry (XRD), Field Emission Scanning Electron Microscope (FESEM) and Archimedes Principle. Hardness and compressive strength was determined using Vickers Microhardness Tester and Universal Testing Machine (UTM) respectively. Results are implying that a high densification and mechanical regime is reached after sintering at low temperature (500 to 800°C) while low densification and mechanical regime is reached after sintering at higher temperature (850 to 1000°C).BG-HA sintered at 800°Cpresented the best results, with high relative density, hardness and compressive strength of 250 HV and 103 MPa, respectively

Small angle neutron scattering study of a gehlenite-based ceramic fabricated from industrial waste

This paper presents a small angle neutron scattering (SANS) study of a novel porous gehlenite-based ceramic, synthesised from a homogeneous powder mixture of soda-lime-silicate (SLS) glass, α-alumina, calcite and calcium fluoride via solid-state sintering at 1200 °C. The products of sintering at single temperatures from 600 to 1200 °C are examined by X-ray diffraction (XRD). Sintering of the mixture below 1200 °C forms two intermediate phases (Na₂ CaSi₃ O₈ and Ca₄ Si₂ O₇ F₂ ). Nepheline and α-alumina are minor phases in the gehlenite-based ceramic fabricated through sintering at 1200 °C. The microstructure of the gehlenite-based ceramic is investigated using field-emission scanning electron microscopy (FESEM) and SANS at the Australian Centre for Neutron Scattering. This study also evaluated the specific surface area of the gehlenite-based ceramic (~3.0 m² cm⁻ ³) from quantitative analysis of SANS data

Physical and mechanical properties of hydroxyapatite reinforced with 45S5 biocomposite

The physical and chemical properties of bioglass have significance in both fundamental and practical applications such as to be used in bone replacements and dental implants which included excellent osteoconductivity and bioactivity, ability to deliver cells and controllable biodegradability. Hydroxyapatite (HA), which has a similar structure as natural bone is prominent due to its biocompatibility and structure. However, it‘s not suitable to be used in load bearing applications due to the low mechanical strength. The introduction of the bioglass in the HA can helps to increase the mechanical strength of the HA so that it‘s able to be used in load bearing application. Melt quenching technique is used to synthesis 45S5 bioglass because it‘s simple, low cost and applicable in large scale industry. Hence, in this study, the physical and mechanical properties of HA, reinforced with sample glass (SG) and treated glass (TG) at different sintering temperatures have been studied. SG has been prepared by the conventional melt quenching technique with 45S5 type of bioglass composition using 45% SiO₂, 24.5% CaCO₃, 24.5% Na₂CO₃ and 6% P₂O₅ as the starting raw materials. Two series of HA reinforced with 45S5 bioglass were produced. The HASG samples were produced by mixing HA and SG according to their weight ratios and followed by pressing them into a pellet form. While, the HATG samples were produced by mixing HA with TG. Whereas, TG is SG sintered at 800 °C. All samples were sintered at 800, 1000, and 1200 °C with a soaking time of 3 hours. All samples under study were tested for density, XRD, FTIR, FESEM and microhardness. The density of SG decreases from 2.26 to 0.44 gcm-3 while molar volume increases from 34.99 to 179.36 cm3mol-1 as sintering temperature increased, which might be due to decomposition of carbonate group. Whereas, the density of HA increased from 1.99 to 3.11 gcm-3 with an increase in the sintering temperature and molar volume decreased from 252.03 to 162.30 cm3mol-1 with the sintering temperature. The density of both HASG and HATG samples was found decrease with an increase in the SG and TG. The density also decreased with the sintering temperature. The molar volume decreased with increasing in the composition of SG and TG, which also increased with temperature. This might be attributed to the replacement of low density SG with HA. The XRD results revealed amorphous phase of SG. After SG undergoes sintering process, the crystalline phase of sodium calcium silicate (Na₂Ca₃Si₆O₁₆), sodium, calcium phosphate (NaCaPO4) and quartz (SiO₂) was observed. It is evident from the study of HASG and HATG samples that SG behaves more as a sintering aid and promotes the conversion of HA to as –tetracalcium phosphate (β–TCP) and α–tetracalcium phosphate (α–TCP). The FTIR results revealed the presence of SiO4, PO4 vibrations in SG, HASG and HATG samples. In addition, the FESEM analysis revealed that by increasing the sintering temperature, the size of closed pores of SG samples increased, while the Ca/P ratio decreased. The FESEM morphology of the HASG and HATG samples showed irregular shapes of grains and closed pore formation. Smaller grain sizes and closed pores were observed in HATG samples. The incorporation of 45S5 bioglass in HA not only changes the crystal structure of HA but also introduced closed pores in the samples which caused the density and hardness reduced as well. This is due to decomposition of oxide material in the glass system. HA reinforced with 45S5 is suitable material for cancellous bone replacement, but the porosity of the sample not fulfilled the requirement for bone scaffold which is interconnected. Nearly, all the calculated Ca/P ratios were within a range for HA which is 1.3 to 2.0. Microvickers hardness of HASG and HATG increased with the sintering temperature and decreased as the composition of SG and TG is increased. This might be due to a coarser microstructure, crystal growth and porosity formation in the samples. Besides that, the hardness value in the range of 0.05–5.0 GPa shows that it's suitable used in cancellous bone applications. The compressive strength data of HATG were comparable to the cancellous bone which shows the compressive strength of 5–10 MPa

Structural, magnetic and dielectric properties of FeշO3-TeOշ glass with starting materials of different particle size

Tellurite based glasses have physical properties that are important for both fundamental and practical applications which are low melting temperature, high dielectric constant,high refractive index, good infrared transmittance and high chemical durability while oxide glass with iron oxide are important due to their magnetic, optical and electrical properties. Hence we proposed to study the structural, magnetic and dielectric properties of Fe2O3-TeO2 glass with different particle size of the starting materials. Glasses in a wide range of composition in the binary system (Fe2O3)x-(TeO2)1-x where x ranges from 0.10 to 0.30 in the interval of 0.05 have been prepared using different sizes of the starting materials by conventional melt quenching technique with Fe2O3 and TeO2 as the starting raw materials. All the glasses in the present work have been confirmed to be amorphous by X-Ray diffraction (XRD) analysis. The short range structures of those binary glasses were examined by Fourier-transform infrared (FTIR) spectroscopy. The density of the glasses was determined by Archimedes Principle. From the empirical data, molar volumes have been computed. Glass stability and glass forming ability was determined using Differential Thermal Analysis (DTA) curve. Magnetic measurement has been performed at room temperature using vibrating sample magnetometer (VSM). The dielectric properties of the samples were also measured using Novocontrol Novotherm High Dielectric Resolution Analyser. The density of the FT series decreases from 5.26 gcm-3 to 5.09 gcm-3 while FTN series decrease from 5.37 gcm-3 to 5.06 gcm-3 with the addition of Fe2O3 due to the replacement of high density TeO2 with Fe2O3. The molar volume of the glass samples shows a reverse trend compared to the density which increases with increasing Fe2O3 where FT series increase from 30.28 cm3 mol-1 to 31.18 cm3 mol-1 and FTN series increase from 29.71 cm3 mol-1 to 31.35 cm3 mol-1. The magnetization analysis shows that all samples have soft magnetic properties. FT glass series were found to exhibit paramagnetic behavior. Binary samples using nano material with x=0.30 has paramagnetic behavior with contribution of superparamagnetic behaviour. The results show that the dielectric permittivity and dielectric loss decrease with frequency and increase with temperature. The behavior of dielectric curves was modeled using equivalent RC circuit consisting combinations of dispersion barrier C*A, quasi – dc, C*B, resistance R, and non dispersive capacitance C∞. The conductivity plot shows two regions, dispersive and flat. This is due to the DC conduction and hopping mechanism. The hopping will take place between the Fe2+ and Fe3+ ions (Fe2+ → Fe3+ + e−) among the different factors, which influence the conductivity

Magnetic behaviour of (Fe2O3)x (TeO2)1-x glass system.

Homogeneous (Fe2O3)x (TeO2)1-x were synthesis using melt- quenching technique for x= 0.1-0.3 in the interval of 0.05. The binary glasses were dark brown in colour. The amorphous structure of glasses was confirmed by the X-ray diffraction spectrum. The physical properties such as density and molar volume have been determined in room temperature and were found decrease with Fe2O3 contents increase. From the vibrating-sample magnetometer (VSM) measurement it was observed that that magnetization of glass increase almost linearly with applied fields and shows paramagnetic materials behavior

Investigation on Structural and Optical Properties of Willemite Doped Mn2+ Based Glass-Ceramics Prepared by Conventional Solid-State Method

Mn-doped willemite (Zn2SiO4:Mn2+) glass-ceramics derived from ZnO-SLS glass system were prepared by a conventional melt-quenching technique followed by a controlled crystallization step employing the heat treatment process. Soda lime silica (SLS) glass waste, ZnO, and MnO were used as sources of silicon, zinc, and manganese, respectively. The obtained glass-ceramic samples were characterized using the X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared (FTIR), UV-Visible (UV-Vis), and photoluminescence (PL) spectroscopy. The results of XRD revealed that ZnO crystal and willemite (β-Zn2SiO4) were presented as major embedded crystalline phases. This observation was consistent with the result of FESEM which showed the presence of irregularity in shape and size of willemite crystallites. FTIR spectroscopy exhibits the structural evolution of willemite based glass-ceramics. The optical band gap shows a decreasing trend as the Mn-doping content increased. Photoluminescent technique was applied to characterize the role of Mn2+ ions when entering the willemite glass-ceramic structure. By measuring the excitation and emission spectra, the main emission peak of the glass-ceramic samples located at a wavelength of 585 nm after subjecting to 260 nm excitations. The following results indicate that the obtained glass-ceramics can be applied as phosphor materials

Development and characterization studies of Eu3+-doped Zn2SiO4 phosphors with waste silicate sources

Structures, morphologies, and properties of europium doped zinc silicate were characterized using X-ray diffractometer, Field emission scanning electron microscope, Fourier transform infrared spectrometer, and UV-vis spectrophotometer. The density of doped zinc silicate shows the trend of increment when the sintering temperature increases. The XRD pattern shows that the material was highly crystalline, having sharp peaks, while the FESEM image reveals the presence of densely packed grains as sintering temperature increased 600 ̊C up to 1000 ̊C. The increase of transmission band intensities at 3443, 1630, 980, 650, 530 cm-1 confirmed the crystallization of Zn2SiO4 crystal in the glass matrix with increasing sintering temperature. Lastly, the increment of energy band gap after sintering temperature at 900 ̊C was related to the stabilization of α-Zn2SiO4 phase in material

Effects of calcination on the crystallography and nonbiogenic aragonite formation of ark clam shell under ambient condition

This paper presents a study of crystallographic evolution of disposed ark clam shell (ACS) after calcination at 400–1400°C which was kept at room temperature under ambient condition in Malaysia during nine months. A better understanding of hydration and recarbonation of ACS powder (≤63 μm) after calcination was discovered by PXRD and FTIR. The research focuses on the crystallographic transformation, biogenic calcite decomposition, and unusual atmospheric aragonite formation in ACS after calcination and atmospheric air exposure. Ex situ PXRD showed calcite present in ACS at ≤900°C. ACS transformed to pyrogenic fcc CaO at ≥800°C after three months. Long term atmospheric air exposure of decarbonized ACS caused nucleation of nonbiogenic aragonite, vaterite, calcite, and portlandite. However, in situ PXRD analysis of ACS at instantaneous temperature without cooling process does not indicate the presence of aragonite, vaterite, and portlandite crystals. FTIR spectra revealed CaO–CO2 bond in ACS dissociated with temperature (600–900°C) to form CaO and CO2. Ca–OH bond was also traced in FTIR spectra of ≥700°C. It resulted by hydroadsorption of CaO with H2O in atmospheric air

The usability of ark clam shell (Anadara granosa) as precursor to produce hydroxyapatite nanoparticles via wet chemical precipitate method

This paper reported the uses of ark clam shell calcium precursor in order to form hydroxyapatite (HA) via the wet chemical precipitation method. The main objective of this research is to acquire better understanding regarding the effect of sintering temperature in the fabrication of HA. Throughout experiment, the ratio of Ca:P were constantly controlled, between 1.67 and 2.00. The formation of HA at these ratio was confirmed by means of energy-dispersive X-ray spectroscopy analysis. In addition, the effect of sintering temperature on the formation of HA was observed using X-ray diffraction analysis, while the structural and morphology was determined by means of field emission scanning electron microscopy. The formation of HA nanoparticle was recorded (~35-69 nm) in the form of as-synthesize HA powder. The bonding compound appeared in the formation of HA was carried out using Fourier transform infrared spectroscopy such as biomaterials that are expected to find potential applications in orthopedic and biomedical industries

Effects of different sintering temperatures on thermal, physical, and morphological of SiO2-Na2O-CaO-P2O5 based glass-ceramic system from vitreous and ceramic wastes

This research involved comprehensive studies on thermal, physical, and morphological properties of SiO2-Na2O-CaO-P2O5 (SNCP) glass-ceramic at various sintering temperatures. The study in SNCP glass-ceramic using soda-lime-silica (SLS) wastes glass and clam shell (CS) wastes as the main raw of materials via conventional melt-quenching technique and solid state sintering are interesting and challenging by considering the research using waste materials to fabricate novel SNCP glass-ceramic. The main peaks, Na3PO4 and Ca3Na6Si6O18 were assigned to high crystallization temperature (Tc) at 650-950 °C. The density of samples increases at 550-750 °C and decreases at 850-950 °C due to the increase of sample thickness and higher specific volume at high sintering temperature. FESEM micrograph showed that existed porous increased at sintering temperature 850-950 °C contributes effect to low densification of the sample