Calcium Borate Research Articles

Anti-wear Chemistry of ZDDP and Calcium Borate Nano-additive. Coupling Experiments, Chemical Hardness Predictions, and MD Calculations

Zinc dialkyl dithiophosphate (ZDDP) is an anti-wear additive for steel surfaces currently used in engine oils. Its anti-wear performance (against abrasion) is due to tribochemical reaction of zinc polyphosphate with abrasive metal oxides nanoparticles, under the combined effect of pressure and shear. However, phosphorous and sulfur are nocuous for environmental issues. Borates are possible candidates to replace phosphates in engine oils. Friction reduction with borates is found to be better than ZDDP but the anti-wear efficiency of borates is lower. In this work, we show how chemical hardness model and computer simulation can explain these different behaviors. Also we show that molecular dynamics is able to predict accurately behavior of mixtures of phosphates and borate. Results show that mixtures of additives with a P:B ratio slightly above unity can be a good compromise to have both good tribological performance and low content of phosphorous and sulfur in the lubricant.

Shimazakiite-4M and shimazakiite-4O, Ca2B2O5, two polytypes of a new mineral from Fuka, Okayama Prefecture, Japan

AbstractShimazakiite occurs as greyish white aggregates up to 3 mm in diameter. Two polytypes, shimazakiite-4M and shimazakiite-4O, have been identified, the former in nanometre-sized twin lamellae and the latter in micrometre-sized lamellae. Shimazakiite was discovered in an irregular vein in crystalline limestone near gehlenite-spurrite skarns at Fuka mine, Okayama Prefecture, Japan. Associated minerals include takedaite, sibirskite, olshanskyite, parasibirskite, nifontovite, calcite and an uncharacterized hydrous calcium borate. The mineral is biaxial (–), with the following refractive indices (at 589 nm): α = 1.586(2), β = 1.650(2), γ = 1.667(2) and 2Vcalc = 53º [shimazakiite-4M]; and α = 1.584(2), β = 1.648(2), γ = 1.670(2) and 2Vcalc = 54.88º [shimazakiite-4O]. Quantitative electronmicroprobe analyses (means of 28 and 25 determinations) gave the empirical formulae Ca2B1.92O4.76(OH)0.24 and Ca2B1.92O4.76(OH)0.24 for shimazakiite-4M and shimazakiite-4O, respectively. The crystal structure refinements: P21/c, a = 3.5485(12), b = 6.352(2), c = 19.254(6) Å , β = 92.393(13)°, V = 433.6(3) Å3 [for shimazakiite-4M]; and P212121, a = 3.55645(8), b = 6.35194(15), c = 19.2534(5) Å , V = 434.941(18) Å3[for shimazakiite-4O], converged into R1 indices of 0.1273 and 0.0142, respectively. The crystal structure of shimazakiite consists of a layer containing B2O5 units (two near-coplanar triangular corner-sharing BO3 groups) and 6- and 7-coordinate Ca atoms. Different sequences in the c direction of four layers are observed in the polytypes. The five strongest lines in the powder-diffraction pattern [listed as d in Å (I)(hkl)] are: 3.02(84)(022); 2.92(100)(10) 2.81(56)(104); 2.76(32)(113); 1.880(32)(11,12,126,118) [for shimazakiite-4M]; and 3.84(33)(014); 3.02(42)(022); 2.86(100)(104); 2.79(29)(113); 1.903(44)(126,118) [for shimazakiite-4O].

Beneficial use of a cell coupling rheometry, conductimetry, and calorimetry to investigate the early age hydration of calcium sulfoaluminate cement

A specific cell was designed to monitor simultaneously the evolution of the viscoelastic properties, electrical conductivity, and temperature of a cement paste with ongoing hydration. Hydration of calcium sulfoaluminate cement by demineralised water or by a borated solution was then investigated as an example. Borate anions acted as set retarders but to a smaller extent than with ordinary Portland cement. The delay in cement hydration resulted from the precipitation of an amorphous or poorly crystallized calcium borate, which also caused a rapid stiffening (and thus a loss of workability) of the paste after mixing. The gypsum content of the CSA cement was shown to play a key role in the control of the cement reactivity.

Copper Absorption by Glass Derived Hydroxyapatite Scaffolds Prepared by Dipping with Polymer Foam

Sodium calcium borate glass derived hydroxyapatite (G-HAP) scaffolds were prepared by dipping with polymer foam. The effects of glasses and ethyl-cellulose (EC) content on the porosity and compressive strength of the scaffolds were studied. The effects of different initial pH value and ions concentration on adsorption performance of copper ions in aqueous solutions were also investigated. The results showed that G-HAP scaffolds could immobilize copper ions in solution effectively. The mechanism of G-HAP scaffolds in immobilizing Cu2+ ions from aqueous solutions was investigated by the X-ray diffraction, Infrared Spectra and Scanning electron microscopy-Energy Dispersive Spectrometer.

Dissolution of vitrified wastes in a high-pH calcium-rich solution

The current baseline for the conditioning of most UK intermediate-level radioactive waste (ILW) is immobilisation using cement. However, vitrification of some UK ILW is being considered as an alternative. One option for the disposal of the resulting vitrified ILW would be to place it in a geological disposal facility in a high-pH environment with cemented ILW and a cement-based backfill. Therefore, the potential effects of such a high pH (∼12.5), calcium-rich cement-based environment on the dissolution behaviour of simulant ILW glasses have been studied using the product consistency test (PCT). Three non-radioactive waste compositions were assessed: a laboratory simulant ILW vitrified in a borosilicate glass and two full-scale simulant vitrified products (a slag containing simulant plutonium-contaminated material and Magnox sludge; and a glass containing clinoptilolite). Powdered samples were leached in saturated Ca(OH)2 solutions for up to 42days at temperatures between 30 and 90°C.In general the rates of dissolution were lower than expected at such a high pH compared to studies in the literature under alkaline conditions. In contrast to the typical dissolution behaviour of high level waste (HLW) glasses, dissolution of the simulant borosilicate ILW glass was initially slow, followed by a period of faster boron and alkali metal release. The saturation/residual regime was not reached within experimental timescales. The rate of dissolution during the period of faster release increased with increasing temperature; the activation energy for this stage of dissolution was calculated to be 47±2kJmol−1 based on boron release. The two full-scale simulant glasses, which contained negligible boric oxide, exhibited conventional static dissolution profiles, and entered the residual rate regime after 7-14days at 50°C. The greater durability of the full-scale simulants is thought to be due to the greater content of network-forming oxides in these glasses compared to the borosilicate glass. It is also suggested that the formation of calcium borates may delay initial hydration of the borosilicate glass in a similar manner to the retardation of cement hydration by soluble borates. More generally, the formation of calcium- and magnesium-containing precipitates on the surface of the vitrified wastes, and agglomeration of the powder, appeared to act to reduce the dissolution rate. Overall these results suggest that calcium has an important role in the long-term durability of vitrified wastes at high pH.

Hydrothermal Fabrication and Wet Chemical Surface Modification of Calcium Borate as Flame Retardant

Hydrothermal Fabrication and Wet Chemical Surface Modification of Calcium Borate as Flame Retardant

Enhancing Mechanical Properties of Ceramic Papers Loaded with Zeolites using Borate Compounds as Binders

NaY zeolite-containing ceramic papers were prepared by a papermaking technique with a dual polyelectrolyte retention system that implied the use of cationic and anionic polymers. To improve their mechanical properties, we found that some borate compounds could be successfully used as ceramic binders. Three types of sodium and/or calcium borates were tested as binders: colemanite, nobleite, and anhydrous ulexite. The improvement in the mechanical properties depends both on the borate used and on the calcination temperature. By XRD it was determined that the faujasite structure collapsed after calcination at 700°C, which limited the final calcination temperature of zeolitic ceramic papers. Different amounts of NaY zeolite were added to ceramic papers and, as observed by SEM, faujasite particles were well distributed throughout the ceramic paper structure. Ceramic papers containing 1.2 wt.% zeolite after calcination at 650°C resulted in structured catalysts that were easy-to-handle, and which can be adapted to different conformations.

Borate-Treated Strand Board from Southern Wood Species: Resistance Against Decay and Mold Fungi

Combined decay and mold resistance of zinc borate-(ZB) and calcium borate-(CB) treated oriented strand board (OSB) from southern mixed hardwood (MHW) and southern yellow pine (SYP) was investigated. Tests were done with a brown-rot fungus, Gloeophyllum trabeum, and a white-rot fungus, Trametes versicolor, for 8 and 12 weeks, respectively. Wood species and fungus type had significant influence on the decay resistance. Decay caused by the brown-rot fungus was evident for all untreated SYP and mixed MHW controls. White-rot fungus did not cause significant sample weight loss for either species group. In the SYP OSB control inoculated with G. trabeum, the hyphae were abundant in wood rays and cell walls where they primarily penetrated through bordered and simple pits. The incorporation of ZB and CB into OSB provided significant protection against the fungi with no significant weight loss observed in the treated OSB. Microscopic analysis showed distinct evidence of fungal colonization and a thinning pattern of cell wall material. Untreated OSB samples from MHW and commercial OSBs were most susceptible to mold growth after 6 weeks. The borate-modified OSB from MHW and SYP effectively prevented the mold growth.

Facile Synthesis of Calcium Borate Nanoparticles and the Annealing Effect on Their Structure and Size

Calcium borate nanoparticles have been synthesized by a thermal treatment method via facile co-precipitation. Differences of annealing temperature and annealing time and their effects on crystal structure, particle size, size distribution and thermal stability of nanoparticles were investigated. The formation of calcium borate compound was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Thermogravimetry (TGA). The XRD patterns revealed that the co-precipitated samples annealed at 700 °C for 3 h annealing time formed an amorphous structure and the transformation into a crystalline structure only occurred after 5 h annealing time. It was found that the samples annealed at 900 °C are mostly metaborate (CaB2O4) nanoparticles and tetraborate (CaB4O7) nanoparticles only observed at 970 °C, which was confirmed by FTIR. The TEM images indicated that with increasing the annealing time and temperature, the average particle size increases. TGA analysis confirmed the thermal stability of the annealed samples at higher temperatures.

Preparation, Characterization, and Tribological Evaluation of a Calcium Borate Embedded in an Oleic Acid Matrix

Calcium borate nanoparticles embedded in an oleic acid liquid matrix (CBNL) with high stability in base oil were synthesized as nanoparticle lubricant additives designed as potential solution to pr...

Combustion synthesis and luminescence characteristic of rare earth activated LiCaBO3

Lithium calcium borate (LiCaBO3) polycrystalline thermoluminescence (TL) phosphor doped with rare earth (Tb3+ and Dy3+) elements was synthesized by novel solution combustion synthesis. The reaction produced very stable crystalline LiCaBO3:D (D= Tb3+ and Dy3+) phosphors. These rare earth doped phosphors material showed maximum TL sensitivity with favorable glow curve shape. TL glow curve of X-ray irradiated that LiCaBO3:Tb3+ and LiCaBO3:Dy3+ samples showed two major well-separated glow peaks. The TL sensitivity of these phosphors to X-ray radiation was comparable with that of TLD-100 (Harshaw). Photoluminescence spectra of LiCaBO3:Tb3+ and LiCaBO3:Dy3+ showed the characteristic Tb3+ and Dy3+ peaks respectively. TL response to X-ray radiation dose was linear up to 25 Gy.

Ulexite-galena intermediate-weight concrete as a novel design for overcoming space and weight limitations in the construction of efficient shields against neutrons and photons

Recently, due to space and weight limitations, scientists have tried to design and produce concrete shields with increased attenuation of radiation but not increased mass density. Over the past years, the authors' had focused on the production of heavy concrete for radiation shielding, but this is the first experience of producing intermediate-weight concrete. In this study, ulexite (hydrated sodium calcium borate hydroxide) and galena (lead ore) have been used for the production of a special intermediate-weight concrete. Shielding properties of this intermediate-weight concrete against photons have been investigated by exposing the samples to narrow and broad beams of gamma rays emitted from a ⁶⁰Co radiotherapy unit. Densities of the intermediate-weight concrete samples ranged 3.64-3.90 g cm⁻³, based on the proportion of the ulexite in the mix design. The narrow-beam half-value layer (HVL) of the ulexite-galena concrete samples for 1.25 MeV ⁶⁰Co gamma rays was 2.84 cm, much less than that of ordinary concrete (6.0 cm). The Monte Carlo (MC) code MCNP4C was also used to model the attenuation of ⁶⁰Co gamma-ray photons and Am-Be neutrons of the ulexite-galena concrete with different thicknesses. The ⁶⁰Co HVL calculated by MCNP simulation was 2.87 cm, indicating a good agreement between experimental measurements and MC simulation. Furthermore, MC-calculated results showed that thick ulexite-galena concrete shields (60-cm thickness) had a 7.22 times (722 %) greater neutron attenuation compared with ordinary concrete. The intermediate-weight ulexite-galena concrete manufactured in this study may have many important applications in the construction of radiation shields with weight limitations such as the swing or sliding doors that are currently used for radiotherapy treatment rooms.

Growth of neodymium lanthanum calcium borate (NdLCB) single crystals by the Czochralski method and its characterisation

The synthesis of neodymium lanthanum calcium borate (NdLCB) was carried out using solid state reaction method. The NdLCB single crystals were grown by the Czochralski method using platinum wire as a seed. The single phase of NdLCB is confirmed by powder X-ray diffraction analysis. EDAX analysis is carried out to find the presence of constituent elements of NdLCB. Single crystal X-ray diffraction analysis was performed to find the lattice parameters and crystal system. Nd concentration in the crystal is determined using ICP-OES measurements. Optical studies such as UV–vis–NIR and photoluminescence were carried out for the NdLCB crystal and the results are analysed. SEM and etching analysis were carried out to analyse the surface morphology and the growth pattern of the as grown NdLCB crystals respectively.

Hydrothermal liquefaction of beech wood using a natural calcium borate mineral

This study reports the effects of a natural calcium borate mineral, colemanite, on the hydrothermal liquefaction of beech wood biomass. Hydrothermal liquefaction experiments were performed at 250, 300 and 350°C with and without colemanite. The highest light bio-oil yield (11.1wt%) and the highest heavy bio-oil yield (29.8wt%) were obtained at 300°C with colemanite. The total bio-oil yields were 22wt% and 41wt% ca. at 300°C without and with colemanite, respectively. The highest heating values were obtained from the hydrothermal liquefaction of biomass using colemanite at 350°C: 23.81MJ/kg for LBO and 27.53MJ/kg for HBO. Most of the identified compounds in the light bio-oils were phenols. The light bio-oil obtained without the catalyst at 300°C contained furfurals. However, these compounds were not observed in the run with colemanite at the same temperature. The heavy bio-oils from the runs both without and with colemanite are composed of phenols, aldehydes, ketones, acids, and benzene derivatives. 4-Methyl-3-penten-2-one was the major compound in the heavy bio-oils produced in the catalytic runs.

Effect of binder on phase transformations in an induction furnace lining

The effect of different additions is considered on properties and phase composition of crucible induction furnace linings, and a reduction of volatility of a binder with water vapor during crucible drying and firing. Calcium and magnesium borates, and other additions are made to the composition of a limning mix instead of boric acid. The possibility is demonstrated by experiment of using boron-containing additions and fluorspar as a binder in crucible induction furnace linings for melting nonferrous metals based on copper.

Crystal growth of lanthanum calcium borate (LCB) single crystals from melt and its characterization

Non-linear optical lanthanum calcium borate (LCB) single crystals were grown by the melt growth method using the Czohralski technique. The polycrystalline LCB compound is synthesized using the solid state reaction method. The grown crystals were characterized by XRD, EDAX, DTA, HRXRD, specific heat, dielectric and NLO studies. The powder XRD pattern revealed the formation of LCB compound and the lattice parameters of the grown crystals were identified through single crystal XRD studies. The melting point of the LCB compound is analyzed by the DTA measurements. Good crystalline nature of the grown crystal is observed from HRXRD analysis. Specific heat measurements in the temperature range 50–550°C are carried out for the as grown crystal samples. The results obtained by the dielectric and NLO studies are also presented.

Effect of partial substitution of aluminum hydroxide with colemanite in fire retarded low-density polyethylene

Metal hydroxides have long been considered as abundant and low-cost fillers for the development of halogen-free flame-retarded polyolefins. However, large filler loading levels are required in the matrix resin to achieve satisfactory fire retardant performance, which results in deteriorated processing characteristics and poor mechanical properties of compounds. Therefore, this study was aimed at improving the fire retardancy of low-density polyethylene and decreasing the total filler loading in the resin using combinations of aluminum hydroxide and a natural hydrated calcium borate, namely, colemanite mineral. Flame retardancy was studied by the mass loss calorimeter analysis, limiting oxygen index measurements, and UL94 classification. Peak heat release rate and total heat evolved were lowered by around 20% and 15%, respectively, with partial replacement of aluminum hydroxide by colemanite, which facilitated the use of lower total filler loading in the resin. Depending on colemanite content and total filler loading, limiting oxygen index was increased by 1%–4% while maintaining the UL94 V-0 rating. Fire retardant effect of colemanite used in conjunction with aluminum hydroxide was attributed to better protective character of fire residues and more effective fuel trapping in the condensed phase. Lower elastic modulus and higher ductility was obtained due to decreased total filler loading in the matrix.

Effects of poly(dimethylsiloxane) and inorganic fillers in halogen free flame retardant poly(ethylene-co-vinyl acetate) compound: A chemometric approach

A quaternary system based on poly(ethylene-co-vinyl acetate) has been studied by Mixture Design in order to analyse the effect of additives on flame retardant properties. The FR components of the system are magnesium hydroxide (MDH), a silicon additive (Sil) based on poly(dimethylsiloxane) and a calcium borate additive (CaB). Many parameters from different flame retardant tests (LOI, UL94-V, DIN 4102 B2 and Cone Calorimeter) are selected as experimental responses and mathematical models with good quality are obtained for most of them. Principal Components Analysis (PCA) on flame retardant parameters points out no particular strong correlations among the three FR tests. The Experimental Design (DoE) approach allows minimization of the number of experiments and analysis of the influence of each component and of the interactions among them. Sil additive shows positive effects on LOI results and in the heat release rate and the fillers, mostly MDH, have positive influence on Cone Calorimeter and vertical burning test performance. Two optimal formulations have been obtained with improved stability of the residue together with LOI value in one case and Cone Calorimeter performance in the other case.

Effect of Preparation Conditions of Calcium Borate Nanoparticles on Oil-Solubility

Oil-soluble calcium borate nanoparticles were prepared in the presence of N2B4O7.10H2O, CaCl2 and oleic acid through in-situ modification method. The effects of five variables (pH value, the dosage of oleic acid, reaction temperature, the molar ratio of reactant and the dosage of absolute ethanol) on oil-solubility were investigated in detail. The as-obtained samples were characterized by infrared spectra (IR) and transmission electron microscope (TEM). It had been found that the average size is in the range of 50-200 nm. The results of the contact angle and active ratio indicate that the surface of calcium borate has been altered from hydrophilicity to hydrophobicity.

Tribological synergism of surface‐modified calcium borate nanoparticles and sulfurized olefin

PurposeSulfurized olefins have been extensively used in many kinds of gear lubricants as EP additives. However, their commercial applications are not totally satisfactory because of the pungent, obnoxious odor and corrosion of copper and copper alloys. The purpose of this paper is to investigate the synergistic effects of one type of calcium borate nanoparticles modified by oleic acid (code to CaBN) and sulfurized olefin, in a kind of mineral base oil MVIS 250, in order to find a potential substitute for sulfurized olefins.Design/methodology/approachOne kind of calcium borate nanoparticle modified by oleic acid (CaBN) was prepared, and its structures were characterized by inductively coupled plasma atomic emission spectroscopy (ICP‐AES), X‐ray power diffraction (XRD) and transmission electron microscope (TEM). The tribological properties of the complex of CaBN with sulfurized olefins (T321) in base oil were evaluated using four‐ball tribotester and compared with CaBN or T321 as individual component. The worn surfaces were investigated by scanning electron microscope (SEM) and X‐ray photoelectron spectroscopy (XPS). In addition, the corrosion‐inhibiting properties of additives were also studied.FindingsThe results of tests show that there are significant synergistic effects on tribological properties between two kinds of additives. Based on the results of SEM and XPS, it can be deduced that a wear resistance film containing B2O3, FeS, FeS2 and CaO was formed on the worn surfaces during the sliding process. Moreover, CaBN and T321 also show excellent synergistic effect on the corrosion‐inhibiting property.Originality/valueThis paper provides a kind of “green” nanoparticle which possesses excellent synergic effect with sulfurized olefins, and gives another selection for industrial applications in which T321 is needed.