Papers by Keyword: Calcium Silicate

Abstract: The high density polyethylene/calcium silicate (HDPE/CS) hybrid composites were prepared using a twin-screw extruder and shaped into test specimens using a compression molding machine. The CS loadings, limited to a total of 20 %vol, were incorporated in HDPE matrix. The morphological behavior, thermal behavior, mechanical properties and bioactivity of the composites were investigated and compared with the neat HDPE under identical conditions. It was found that poor dispersion of the CS particles was observed in the composites with high CS loadings because of only weak interaction between CS particles and HDPE. The percentage of HDPE crystallinity was insignificantly changed when adding CS particles in the HDPE/CS composites. The stiffness of the HDPE/CS hybrid composites was strongly improved and reached the maximum values of flexural and compressive moduli at 1190 MPa (35% greater than the neat HDPE) and 581 Ma (17% greater than the neat HDPE), respectively, with 15 % CS loading. The higher the CS loading, the greater the hardness of the HDPE/CS composites were seen. However, the flexural strength of the HDPE/CS composites (up to 15% CS loading) was not considerably altered. Moreover, both flexural and compressive properties were lowered with higher CS content (20%) due to the generated voids in the HDPE/CS composites. After soaking in simulated body fluid (SBF) at 36.5°C for 7–49 days, the HDPE/CS composites could induce the formation of ball-like HA aggregates covering on the composite surface, indicating its bioactivity. This research successfully prepared HDPE/CS hybrid composites with fast rate bioactivity and their modulus and strength values were within those for human trabecular bone. Therefore, the HDPE/CS hybrid composites had potentially used as bioactive materials for medical applications.

Abstract: Present usage of Metal Matrix Composites is high in engineering applications. Especially, Al 6065 aluminum alloy is finding suitable for many applications of engineering components. In this work, a metal matrix composite has prepared with the pure Al 6065 aluminum alloy as matrix and Calcium silicate (CaSiO₃) as reinforcement using bottom pour stir casting machine. The percentage of Calcium silicate (CaSiO₃) has been increased from 1 % to 4 % in steps of 1% by weight. The reinforcement has been distributed over the matrix for which micro structural analysis and hardness test has been performed. The hardness values are found to be increasing with increase of reinforcement.

Abstract: The morphology and surface topography of calcium silicate coated on Ti6Al4V implant were studied using field emission scanning electron microscopy (FESEM) and X-ray diffraction analysis (XRD) respectively. The surface of titanium alloy plates was mechanically ground with 320, 800 and 1200 grits of SiC abrasive paper followed by surface polishing into mirror-like finish. The synthesized β-CaSiO₃ was deposited onto the Ti6Al4V substrate using electron beam evaporator. After coating, calcium silicate was heat treated at 500 °C for 1 hour. Characterization of the calcium silicate coated on Ti6Al4V substrate using e-beam evaporation technique demonstrated that 5 wt% of PVA addition was able to improve the coating-to-substrate adhesion.

Abstract: Calcium silicate was successfully synthesized using agricultural byproduct such as rice husk ash and shell of snail namely Pomacea canaliculata by solid state reaction. Chemical composition of silica in rice husk ash and calcium oxide in shell were 91.50 and 98.25%, respectively by X-ray fluorescent determination. The rice husk ash and shell in molar ratio of 1:1 were milled for 5-8 hr and calcined at 800-1000 ^°C for 2 hr. The Fourier transforms infrared spectra and X-ray diffractometry pattern were confirmed the formation of calcium silicate as the milling time increased.

Abstract: A novel and facile process called “alternative loop immersion method” formed bioactive and biocompatible Zn-doped calcium silicate coating over the drug-loaded titania nanotube arrays to improve the properties of drug release. The samples were characterized by scanning electronic microscope (SEM), x-ray diffraction (XRD) and fourier transform infrared (FT-IR). The results show that TNTs modified by Zn-doped calcium silicate coating possess improved drug release characteristics with reduced burst release (from 83% to 66%) and prolonged drug release (from 11 days to over 15 days). This approach provides an alternative to tailor the surface of TNTs and offer considerable propects for diverse biomedical applications.

Abstract: The article deals with energy rehabilitation of a building with damaged waterproofing of its lower structure. The reference construction is made of fired bricks, whose functional properties are perfectly fine, but the thermal insulation properties are insufficient for this time. The most common solution of such a problem is the application of a thermal insulating material based on expanded polystyrene on the building envelope. Unfortunately, these solutions often entail the risk of moisture problems in places that appeared to be dry before. The article compares the current solution with the new one relying on material based on calcium silicate [4] with high moisture transport capabilities as an alternative insulation of these buildings.

Abstract: The silica, one of the by-products of fluorine industry, contains soluble fluoride which is harmful to the environment. Therefore, a study on fixing soluble fluoride was conducted by hydrothermal method with the silica as raw material and adding hydrated lime (HL), and the nanowires-reticulated calcium silicate with high specific surface area up to 143.8m²/g was prepared at the same time. The prepared calcium silicate was used as adsorbent in the experiments of phosphorus (P) adsorption from aqueous solution, the adsorption capacity, adsorption rate and P removability were characterized. The results show that the preparation conditions affect distinctly the adsorption performances of calcium silicate, especially, the dosage Ca/Si molar ratio. For the optimized calcium silicate sample, the total P adsorption capacity is 125.7mg/g and the exchange rate of Ca²⁺ reaches 95.8%, the P residual concentration is only 0.3mg/L, the saturated adsorption time is 3900 min, when the simulation solution with P concentration of 100 mg/L is treated. The P residual concentration is only 0.1mg/L for the simulation solution of 56.12mg/L.

Abstract: Calcium silicate phosphors, Ca2-xSiO4(CS):Eu3+x, CS:Eu2+x and Ca2-y-zMgSi2O7 (CMS):Eu2+y,Dy3+z were prepared by the solid state reaction. The phases in CS:Eu3+ system were β- and αL’ -types. The fluorescent color under a black-light irradiation was red and the emission spectrum consisted of 590nm(αL’), 615nm(β) and 625nm(αL’) peaks. The emission intensity took a maximum value at x=0.2. The addition of B3+ accelerated the solid solution of Eu3+. The phase in CS:Eu2+ system was β-type only. The fluorescent color was yellow-green(520nm). The emission intensity took a maximum value at x=0.01. The CMS product showed the akermanite phase. The lattice constants of CMS:Eu2+ increased with increasing Eu content, but those became constant at y>0.05. The fluorescent color of CMS:Eu2+ was yellow-green and the emission intensity took a maximum value at y=0.03. In the case of CMS:Eu2+0.03,Dy3+z, the fluorescent color and the afterglow color were same, yellow-green. The emission intensity took a maximum value at z=0.06. The longest afterglow time, 23min., was obtained at z=0.09. The trap depth were 0.64-0.69 eV.

Abstract: Abstract: Calcium silicate (CS) ceramics have good biocompatibility, high bonding strength with titanium alloy substrates, and are potential candidates for implant coating materials. The osteo-integration of coated implants with host bone tissue is greatly affected by the degradation of these coating materials in biological fluid. In this paper, zirconia adopted calcium silicate (CaO-ZrO2-SiO2, CZS) ceramic powder was synthesized. Plasma spraying was used to prepare the coating with Ti-6Al-4V as substrates. Human bone marrow-derived stromal cells (hBMSCs) culture system was used to evaluate the cytocompatibility of the CS and CZS coatings. Results showed that more cells were adhered to the CZS coating with high proliferation ratio than those on CS. The dissolution of CS and hereby elevated pH value were contributed to the decreased cell adhesion and proliferation.

Abstract: A series of calcium silicate/rubber composites with different CaSiO3 contents was prepared. micro-morphology, vulcanizing properties and mechanical properties of CaSiO3/rubber were were characterized. It can be observed that mean particle size of CaSiO3 was 2.627 µm. The micro-morphology of particles were honeycomb structure on the particles of CaSiO3. As compared with NR, the least torque enhanced wtih increasing CaSiO3 content. Curing rate reduced with a rise of CaSiO3 content. The tensile strength and the elongation of composites was increased with increasing CaSiO3 content.