Calcium Borate Research Articles

Thermal and flame properties of calcium borate and intumescent ammonium polyphosphate in epoxy/glass fiber composites

The thermal and flammability properties of halogen-free flame retardants, calcium borate and intumescent ammonium polyphosphate, were evaluated on epoxy/glass fiber composites. The evolved volatile products under thermal stresses were analyzed accordingly, and the thermal decomposition of the composites was studied. It was determined that ammonium polyphosphate and calcium borate releases water vapor and carbon dioxide during their thermal decomposition, as a method to overcome the fire. Ammonium polyphosphate that achieved the V-0 rating at 5 vol% loading had showed better fire resistance than calcium borate that failed to achieve any rating even at high loading of 20 vol%. However, the calcium borate had recorded higher residual content. The combination of 1 vol% calcium borate and 4 vol% ammonium polyphosphate exhibited a synergistic performance by mass producing more char as a protection for the composites. Nevertheless, this synergism was not observed with the other combination, which comprised a 50:50 ratio of ammonium polyphosphate–calcium borate.

Boron removal by means of chemical precipitation with calcium hydroxide and calcium borate formation

Boron removal was investigated by chemical precipitation from aqueous solutions containing boron using calcium hydroxide. pH, initial boron concentration, amount of Ca(OH)2, stirring speed and solution temperature were selected as operational parameters in a batch system. The highest boron removal efficiency was reached at pH 1.0. Increasing initial boron concentration and amount of calcium hydroxide raised to boron removal efficiency. Boron removal efficiency was highest at a stirring speed of 150 rpm. The most important parameter affecting boron removal efficiency was solution temperature. Increasing solution temperature increased importantly boron removal. XRD analysis showed that CaB3O3(OH)5·4H2O, which is a borate mineral called inyoite, occurred between Ca(OH)2 and borate ions. As a result of the obtained experimental data, when the optimum operational conditions were selected, over 96% of boron removal efficiency was reached by this method.

Synthesis, crystal structure and properties of a new lead calcium diborate

Single crystals of a novel lead calcium borate, PbCaB2O5, have been successfully grown by spontaneous crystallization method for the first time. The single-crystal X-ray structural analysis showed that PbCaB2O5 crystallizes in the triclinic space group P1¯ with a = 3.6736(6) Å, b = 6.5363(11) Å, c = 9.7585(17) Å, α = 100.504(2)°, β = 90.752(2)°, γ = 91.627(2)°, and Z = 2. The crystal structure consists of isolated B2O5 units, PbO5 and Pb/CaO7 polyhedra. Spectrum properties of PbCaB2O5 were reported.

Properties of flame-retardant fillers in polypropylene/ethylene propylene diene monomer composites

The incorporation of zinc hydroxy stannate (ZHS), calcium borates (CBs), and NP-100 as flame-retardant fillers in polypropylene (PP) ethylene propylene diene monomer (EPDM) blends was investigated. The composites were prepared using an internal mixer and were molded using a compression mold to form test samples. Studies on the effect of filler loading (15, 30, 45, and 60 vol%) on the flame-retardant, thermal stability, and tensile properties were reviewed. A study on flame retardancy and thermal stability of ZHS, CB, and NP-100 fillers found that NP-100 has better flame retardancy compared with ZHS and CB even though NP-100 exhibits lower thermal stability compared with ZHS and CB. The mechanical properties of ZHS are the highest, followed by CB. NP-100 has the lowest mechanical properties. Tensile strength, Young’s modulus, and strain at break of 30 vol% ZHS are slightly higher compared with other loadings. In addition, 30 vol% CB has the highest mechanical properties for PP/EPDM/CB system but has slightly lower mechanical properties compared with 30 vol% ZHS-filled PP/EPDM composites.

Incorporation of B2O3 in CaO-SiO2-P2O5 bioactive glass system for improving strength of low-temperature co-fired porous glass ceramics

Bioactive glass ceramics (BGCs) have different rates of biodegradation and mechanical properties depending on their chemical compositions and sintering temperatures. The present study was aimed to develop the boron-rich, phosphorus-low CaO–SiO2–P2O5–B2O3 bioactive glasses (BG-Bx, X=0, 10, 20) potentially for improving the mechanical properties of BGCs via low-temperature co-fired process. The B2O3-free BG-B0 shrunk well at ~726°C and melted at over 1050°C, while the onset shrinking and melting temperatures of the 20mol% B2O3-doped BG-B20 was lowered to ~648°C and ~952°C, respectively. The BG-B20 thermally treated at 850–950°C was transformed into wollastonite and calcium borate, and crystallization decreased the kinetics but did not inhibit the development of hydroxyapatite on their powder and disc surface when immersed in simulated body fluid. The in vitro degradation in Tris buffer confirmed that the degradation rate markedly increased with increasing boron content in BG-Bx. The compressive strength and flexural strength of the 10% BG-B20-reinforced 45S5 porous BGC sintered at 850°C was nearly four times than that of 45S5 porous constructs. These studies suggest that the boron-rich, phosphorus-low CaO–SiO2–P2O5–B2O3 system is a promising biomaterial and potential low temperature co-fired aid for improving the mechanical and biological properties of porous BGCs.

Preparation and tribological properties of a kind of lubricant containing calcium borate nanoparticles as additives

PurposeNanoparticles are not well dispersed in non‐polar organic solvents due to their hydrophilic property which limits their applications in lubricant oils. To improve the oil‐solubility of nanoparticles, a novel technology was used to prepare a kind of lubricant containing calcium borate nanoparticles.Design/methodology/approachThe microstructures of the prepared nanoparticles were characterized by transmission electron microscope (TEM) and infrared spectra (IR). Tribological properties of calcium borate nanoparticles used as additive in base oil were evaluated using four‐ball tribotester and SRV tribotester, and the worn surface of the steel ball was investigated by Polarized microscope (PM) and X‐ray photoelectron spectroscopy (XPS). In addition, the dispersing stability and antioxidation property of lubricant containing nanoparticles were also studied.FindingsThe results indicate that the average size of the prepared nanoparticles is in the range of 50‐100 nm, and the surface of the nanoparticles was altered from hydrophilicity to hydrophobicity. At the same time, the nanoparticles can be well dispersed in the base oil totally under novel process which has no significantly negative effect on the antioxidation property. The results of tribological tests show that calcium borate nanoparticles under the novel process (CBNN) show better antiwear property and friction‐reducing property in base oil compared to calcium borate nanoparticles under tradition process (CBNT). Based on the results of PM and XPS, it can be deduced that a continuous resistance film containing depositions and the tribochemical reaction products such as B2O3, FeB, Fe2O3 and CaO formed during the sliding process.Originality/valueThe main innovative thought of this work lies in dealing with the oil‐solubility problem through the combination effect of surface modification and special blend process of lubricating oil, and this method was first used to prepare lubricant containing calcium borate nanoparticles. It should be helpful for the borate nanoparticles used as additives in engine oil, gear oil and other industrial lubricants.

Efficacy of colemanite against mould fungi on rubber wood veneer

Colemanite, also called as hydrated calcium borate hydroxide, is a borate mineral found in evaporite deposits of alkaline lacustrins environments. It is a secondary mineral that forms by alternation of borax and ulexite. As this chemical is not toxic to human beings and other mammals, it has been chosen for the present preliminary work on assessing the efficacy against mould fungi on rubber wood veneers. Colemanite at two different levels of concentrations, 3 and 5 % was tested against moulds and it has been found that 5 % concentration acts as an effective mouldicide. In India this is the first report where colemanite was used against mould fungi.

Controllable white light emission from Dy3+–Eu3+ co-doped KCaBO3 phosphor

Potassium calcium borate, KCaBO3:Eu3+ phosphors with various Dy3+ concentrations (0–3 wt%) were synthesized by solid state reaction and studied for the first time. Under various UV–violet excitations, the obtained single monoclinic phased Dy3+–Eu3+ co-doped KCaBO3 polycrystalline phosphors emit a combination of yellow–blue and red–orange wavelength giving intense white light, which can easily be controlled by varying the concentration of Dy3+. The increase in white light emission with the increase of Dy3+ concentration indicates the efficient energy inter-ion transfer from Dy3+ to Eu3+ ions. Furthermore, the observed emission lifetimes and the intense white light emission are suggestive exploration for the present phosphor for potential optoelectronic applications such as white light-emitting phosphor for blue LEDs chips.

Hydrothermal Synthesis of Calcium Borate Whiskers

A type of calcium borate whiskers with highly thermal stability was synthesized by hydrothermal method at 180 °C for 2 h, using borax, calcium chloride and sodium hydroxide as raw reactants. The X-ray powder diffraction (XRD) indicated that as-prepared products were composed of monoclinic Ca2B2O5·H2O phase. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed calcium borate whiskers with a length of 50~100 μm and diameter 1.0 ~3.0 μm. Selected-area electron diffraction (SAED) pattern showed that the calcium borate whiskers were single crystalline structure. The adjustment of temperature of hydrothermal reaction, can lead to obvious morphology changes of products, and the possible chemical reaction and growth mechanism were proposed. Furthermore, the analysis of thermogravimetry (TG) showed the calcium borate whiskers released crystal water at 370~425 °C.

Effect of Synthesis Condition on the Solubility of Surface-Modified Calcium Borate Nanoparticles

To find a kind nanoparticles can be used as additive in lubricants, oil-soluble calcium borate nanoparticles were prepared in the present of Na2B4O7.10H2O, CaCl2, and oleic acid as modifier by in-situ method, and the effects of different reaction conditions on the coil-solubility of the nanoparticles were investigated. The results indicate that the surface of calcium borate was altered from hydrophilicity to hydrophobicity after the modification with oleic acid, and so the nanoparticles possess high solubility in mineral base oils. Moreover, TT-IR confirms that the bond of oleic acid onto the surface of calcium borate nanoparticles exists.

Determination of thermoluminescence kinetic parameters of thulium doped lithium calcium borate

For the first time kinetic parameters of thulium doped Lithium calcium borate (LCB) Thermoluminescence (TL) material are reported here. Irradiated LCB:Tm 3+ powder has revealed two intense TL glow peaks one at 510 (peak 1) and the other at 660 K (peak 2). Activation energy ( E ), frequency factor ( s ) and order of kinetics ( b ) of these peaks were determined by various heating rate (VHR), initial rise (IR), and peak shape (PS) methods. The trap depth and frequency factor determined for peaks 1 and 2 of LCB:Tm phosphor using VHR and IR methods are in good agreement. The average activation energy of peaks 1 and 2 obtained by these methods is 1.62 and 1.91 eV respectively. The frequency factors of peaks 1 and 2 are in the range of 10 13–16 and 10 12–14 sec −1 respectively. The E and s values estimated using the glow peak shape dependent parameters are relatively less compared to the values obtained from other methods. The large difference in these values is due to the complex nature of the glow curves. The order of the kinetics process for complex glow curve peaks could not be assigned on the basis of shape parameters alone but T m response on absorbed dose is to be considered for final confirmation. Glow peaks 1 and 2 of LCB:Tm 3+ obey first and general order kinetics respectively. ► Trap depth and frequency factor are determined for the peaks at 510 and 660 K of LCB:Tm. ► Parameters obtained by various heating rate and initial rise methods are in good agreement. ► Trap depth of peak 1 and peak 2 is 1.61 eV and 1.91 eV respectively. ► T m response to absorbed dose is used to distinguish a first order or non-first order kinetics.

Electrophoretic deposition of porous CaO–MgO–SiO2 glass–ceramic coatings with B2O3 as additive on Ti–6Al–4V alloy

The sub-micron glass-ceramic powders in CaO-MgO-SiO(2) system with 10wt% B(2)O(3) additive were synthesized by sol-gel process. Then bioactive porous CaO-MgO-SiO(2) glass-ceramic coatings on Ti-6Al-4V alloy substrates were fabricated using electrophoretic deposition (EPD) technique. After being calcined at 850°C, the above coatings with thickness of 10-150μm were uniform and crack-free, possessing porous structure with sub-micron and micron size connected pores. Ethanol was employed as the most suitable solvent to prepare the suspension for EPD. The coating porous appearance and porosity distribution could be controlled by adjusting the suspension concentration, applied voltage and deposition time. The heat-treated coatings possessed high crystalline and was mainly composed of diopside, akermanite, merwinite, calcium silicate and calcium borate silicate. Bonelike apatite was formed on the coatings after 7days of soaking in simulated body fluid (SBF). The bonding strength of the coatings was needed to be further improved.

Treatment of boron-containing optoelectronic wastewater by precipitation process

A greener and more cost-effective process was studied for boron removal from synthetic and optoelectronic wastewater by precipitation with lime (Ca(OH) 2) under moderate temperature (45–80 °C). The precipitates were characterized by SEM, XRD, and XPS, and confirmed that it was calcium borate (Ca 2B 2O 5.H 2O). Pseudo-first order kinetic model fits the reaction satisfactorily. The activation energy (E a) of the reaction was 45.1 kJ/mol, implying that the reaction rate was controlled by surface chemical reaction. The calcium borate precipitate formed at 60 °C was cooled to room temperature gradually and no re-dissolution of boron was found, indicating that calcium borate was a stable compound. Boron removal in both synthetic wastewater and optoelectronic wastewater increased with increasing pH and stabilized at equilibrium pH of 12.4 ± 0.1. The optimum dose of Ca(OH) 2 was 10 g/L, at which 87% of boron was removed at 60 °C. Experimental results showed that precipitation process using lime was very effective and efficient to remove boron from concentrated wastewater.

Thermo-optical characteristics and concentration quenching effects in Nd3+doped yttrium calcium borate glasses

In this work we present a comprehensive study of the spectroscopic and thermo-optical properties of a set of samples with composition xNd(2)O(3)-(5-x)Y(2)O(3-)40CaO-55B(2)O(3) (0 ≤ x ≤ 1.0 mol%). Their fluorescence quantum efficiency (η) values were determined using the thermal lens technique and the dependence on the ionic concentration was analyzed in terms of energy transfer processes, based on the Förster-Dexter model of multipolar ion-ion interactions. A maximum η = 0.54 was found to be substantially higher than for yttrium aluminoborate crystals and glasses with comparable Nd(3+) content. As for the thermo-optical properties of yttrium calcium borate, they are comparable to other well-known laser glasses. The obtained energy transfer microparameters and the weak dependence of η on the Nd(3+) concentration with a high optimum Nd(3+) concentration put this system as a strong candidate for photonics applications.

Design parameters of boric acid production process from colemanite ore in the presence of propionic acid

In this study, three different boric acid production process alternatives which can be performed in the presence of propionic acid and/or calcium propionate were evaluated. The process in which calcium propionate is the recycling component was selected as the best alternative and modeled. Some of the design parameters were determined for the selected process. These parameters are solubility change of boric acid in the presence of calcium propionate at 25 °C, 35 °C and 75 °C, precipitation risk of calcium borate components in concentrated boric acid solutions containing calcium propionate, and the effect of calcium propionate on the solution pH with respect to free sulfuric acid concentration. According to the determined parameters, principal reactions occurred in the process, and other process parameters obtained by industrial practice, mass balances were conducted and all flow rates were calculated. In the process, calcium propionate concentration in production liquor must be kept lower than 3% and the reaction must be carried out without any free sulfuric acid in order to perform the process according to the model.

Synergistic fire retardancy of colemanite, a natural hydrated calcium borate, in high-impact polystyrene containing brominated epoxy and antimony oxide

This study explores for the first time the synergistic fire retardant action of natural hydrated calcium borate, namely the mineral colemanite, which partially replaces antimony oxide in brominated flame retardant high-impact polystyrene compounds. Various antimony oxide to hydrated calcium borate ratios were employed keeping the brominated flame retardant additive at a constant loading level. With partial colemanite substitution for antimony oxide, lower heat release rate, total heat evolved and fire growth index was obtained under forced flaming fire conditions. Synergism was also seen in limiting oxygen index along with maintained V-0 classification in UL-94 tests. Regarding fire behaviour and flammability ratings, a large antimony oxide to calcium borate ratio provided ultimate fire retardant performance whereas magnitudes of synergism in average heat release rate and total heat evolved tend to be higher towards a smaller ratio. Effective heats of combustion and structural/morphological characterization of fire residues ascribed the underlying mechanism demonstrated by hydrated calcium borate to the formation of a consolidated residue that co-operates with the dominant gas phase fire retardancy originating from bromine–antimony synergism. It is thus proposed that coupling is achieved between gas phase and condensed phase modes of action increasing the overall fire retardant effectiveness. Along with enhanced fire retardancy, thermal stability and mechanical properties were satisfactorily maintained with the use of hydrated calcium borate at a variety of loading levels in compounds.

Skarn-greisen deposits of the lost river and mount ear ore field, Seward Peninsula, Alaska, United States

The boron, tin, tungsten, beryllium, and fluorite deposits of the York Range, Seward Peninsula, represent the continuation of the Asian segment of the Pacific ore belt and are globally conjugate with the Verkhoyan-Chukotka ore province of Northeastern Russia. They are localized in the alteration aureoles of dolomites and limestones of the Paleozoic Port Clarence Formation at the contact with the Mesozoic leucocratic granites and genetically belong to the magnesian-skan ore formation. Ore-generating process developed in marbles, skarns, and greisens under hypabyssal conditions in several stages and was accompanied by sequential formation of polymineral assemblages. Early mineralization is represented by magnetite in prograde pyroxene skarns after dolomites. Postmagmatic ore stage is represented by formation of endogenous borates, including their tin-bearing Mg-Fe species, in the magnesian skarns, superposition of calcareousskarn assemblages containing calcium borates, borosilicates, and scheelite, formation of cassiterite and wolrframite in the greisenized granites, and precipitation of sulfides, chrysoberyl, and fluorite. The mineral composition of the rocks and ores was formed under the influence of F-bearing hydrothermal solutions, which caused the presence of fluorine in borates, rock-forming silicates, and the replacement of calcite by fluorite. Boron, tin, beryllium, and fluorine participate at all the stages of endogenous process, but the mineral modes of their occurrence are varied, which is confirmed by data on their chemical composition. The results of studying the skarns and ores of the Alaska deposits are of great applied and scientific significance, and can be used for study of skarn-greisen deposits localized at the contacts of carbonate rocks with granite intrusions of the Pacific ore belt and other world’s regions.

Dehydration processes in borate minerals: pentahydroborite and nifontovite from Fuka Mine, Okayama Prefecture, Japan

AbstractData on the dehydration of pentahydroborite, CaB2O(OH)6·2H2O and nifontovite, Ca3B6O6(OH)12·2H2O from the Fuka mine, Japan are presented. Critical temperatures of the dehydration of the borates were determined by thermogravimetric analysis/differential thermal analysis measurements. The untreated mineral samples and their heating products were investigated by X-ray diffraction and Raman spectroscopy. Upon dehydration, both minerals decompose and undergo amorphization, and at greater temperatures crystallize as an orthorhombic calcium borate, CaB2O4 (Pnca). The dehydration paths of the two minerals are different, with nifontovite showing a greater resistance to decomposition and amorphization than pentahydroborite. Differences in the dehydration processes are related to the residuals of the water content and structural accommodation of the borate polyanion.

Fluoride removal performance of glass derived hydroxyapatite

Research highlights: {yields} Novel sodium calcium borate glass derived hydroxyapatite (G-HAP) is prepared. {yields} Micro-G-HAP adsorbs F{sup -} ions in solutions more effectively than commercial nano-HAP. {yields} The adsorption kinetics and isotherms are well fitted by a second order kinetic model and Freundlich isotherm model. -- Abstract: A novel sodium calcium borate glass derived hydroxyapatite (G-HAP) with different ranges of particle size was prepared by immersion sodium calcium borate glass in 0.1 M K{sub 2}HPO{sub 4} solution by the ratio of 50 g L{sup -1} for 7 days. The unique advantage of G-HAP for the adsorption of fluoride ions in solutions was studied. The effects of size and quantity of particles, pH value and adsorption time on adsorption performance were investigated. The maximum adsorption capacity was 17.34 mg g{sup -1} if 5 g L{sup -1}, <100 {mu}m G-HAP was added to a solution with an initial pH value of 6.72 and the adsorption time was 12 h. The results showed that the micro-G-HAP could immobilize F{sup -} in solution more effectively than commercial nano-HAP, which makes potential application of the G-HAP in removing the fluoride ions from wastewater. The adsorption kinetics and isotherms for F{sup -} could be well fittedmore » by a second order kinetic model and Freundlich isotherm model respectively, which could be used to describe the adsorption behavior. The mechanism of G-HAP in immobilizing F{sup -} from aqueous solutions was investigated by the X-ray diffraction (XRD), infrared spectra (IR) and scanning electron microscopy (SEM).« less

Preparation, Characterization and Tribological Evaluation of Calcium Borate Nanoparticles as Lubricant Additives

To develop a potential substitute for conventional lubricant additive, pure calcium borate nanoparticles (PCBN) and calcium borate nanoparticles modified with oleic acid (MCBN) were prepared. The microstructures of the as-obtained samples were characterized using X-ray power diffraction (XRD), transmission electron microscope (TEM) and infrared spectra (IR), and the dispersing stability of oil containing nanoparticles was also evaluated. Tribological properties of MCBN used as lubricating additive were evaluated using four-ball tribometer and compared with that of PCBN. The results indicate that MCBN show better antiwear and friction-reducing property than PCBN. The worn surface of the steel ball lubricated with MCBN was investigated by Polarized microscope (PM) and X-ray photoelectron spectroscopy (XPS), and the action mechanism of MCBN during friction process was preliminarily discussed.