hBN Nanoparticles Research Articles

DEVELOPMENT OF NEXT GENERATION DIAMOND TOOLS BASED ON SUPERHARD MATERIALS WITH NANOMODIFIED BINDER FOR STEEL AND CAST IRON MACHINING

The paper demonstrates the possibility of using Next100 type binders alloyed with nickel and modified with WC, ZrO 2 and hBN nanoparticles for the manufacture of cutting tools based on superhard materials intended for steel and cast iron machining. It was found that nickel alloying of the binder makes it possible to increase its impact strength by 2,5 times and significantly improve the life of tool segments while in operation. Introduction of WC, ZrO 2 and hBN nanoparticles into the binder increases its strength by 100–150 MPa and hardness by 5–7 HRB. In the presence of WC nanoparticles, the adhesion of cubic boron nitride to the binder increases. The optimal ratio of diamond to CBN grains in the coating is determined for better tool performance – 75 : 25. The paper reveals the formation of amorphous boron nanoclusters at the at CBN-binder interface, and dissolution of a small amount of nitrogen in the binder components during hot pressing.

Tribological effects of nano-based engine oil diluted with biodiesel fuel

The aim of this study was to investigate the tribological effects of nano-based engine oil diluted with biodiesel fuel. The nano-oil was prepared by disperse an optimal composition 0.5 vol.% of 70 nm hexagonal boron nitride (hBN) nanoparticles in diesel engine oil using sonication technique. Sample was diluted by difference percentages of B100 biodiesel fuel in range of 5-20 vol.%. The tribological test was performed using a four-ball tribometer. It was found that the addition of biodiesel fuel increases the coefficient of friction (COF) and seizure wears as compared with nano-oil. However, there is no significant effect on the extreme pressure (EP) properties, where the seizure for all tested samples starts to occur at 981 N.

Development of a Next Generation of Diamond Tools Based on Superhard Materials with a Nanomodified Binder for Steel and Cast Iron Machining

The possibility of using binders of the Next100 type alloyed with nickel and modified with WC, ZrO2, and hBN nanoparticles for fabricating a cutting tool based on superhard materials and intended for steel and cast iron machining is shown. It is established that alloying the binder with nickel makes it possible to increase its impact viscosity by a factor of 2.5 and substantially improve the resistance of tool segments during operation. An increase in binder strength by 100–150 MPa and hardness by 5–7 HRB is provided due to the introduction of WC, ZrO2, and hBN into it. The adhesion of cubic boron nitride to a binder increases in the presence of WC nanoparticles. The optimal ratio of diamond single crystals and cubic boron nitride in a working layer, at which maximal service characteristics of the tool are attained, is determined to be 75: 25. The formation of nanoclusters of amorphous boron at the interface of cubic boron nitride and a binder and dissolution of a small amount of nitrogen in binder components during hot compaction are revealed.

Experimental investigation of heat transfer enhancement and viscosity change of hBN nanofluids

Hexagonal boron nitride (hBN) is a highly stable dielectric ceramic material that exhibits versatile properties such as, exceptionally high thermal conductivity and good chemical inertness. Due to its layered hexagonal crystal structure, hBN is the softest form among the other polymorphs of BN. Preparation, stability and thermophysical properties of hBN containing DI water, ethylene glycol (EG) and EG–DI water mixture (by volume 50%) based nanofluids are investigated. For this purpose a series of well dispersed, stable nanofluids, containing hBN nanoparticles with a mean diameter of 70nm, are produced with a two-step method, relying on ultrasonication and use of surface active materials such as sodium dodecyl sulfate (SDS) and polyvinyl pyrrolidone (PVP). The effect of these surfactants on the base fluids’ thermophysical properties is measured. The stability is evaluated by quantitative methods such as, time dependent zeta potential, and thermal conductivity measurements. Morphological characterization of nanofluids is completed by qualitative methods such as, SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy). The thermal conductivity enhancement of nanofluids, with particle volume concentration varying between 0.03% and 3%, is investigated experimentally in accordance with their increase in viscosity. It is observed that the hBN nanofluids have remarkably higher thermal conductivity values than their corresponding base fluids, depending on the volume concentration of dispersed nanoparticles. Moreover, water based hBN nanofluids with relatively dilute particle suspensions, exhibits significant increase in thermal conductivity with respect to the viscosity increase.

Nanocomposite glass coatings containing hexagonal boron nitride nanoparticles

Glass coatings composed of SiO2–K2O–Li2O, containing non-modified and fluorosilane modified hexagonal boron nitride (hBN) nanoparticles, were prepared on stainless steel plates through sol–gel spin-coating method. Coatings were examined by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), atomic force microscopy (AFM) and thermo-gravimetric analysis (TGA). 1.3–2.5µm thick uniform coatings were obtained after curing at 500°C for 1h. The coatings adhered well to the steel substrates. It was determined by salt spray tests that the coatings enhance corrosion resistance. The aim of hydrophobic fluorosilane modification of hBN nanoparticles was to enrich hBN quantity on the top surface of the coatings. Coatings containing fluorosilane modified hBN nanoparticles presented slightly lower friction coefficient values than the other coatings.

Modification of hexagonal boron nitride nanoparticles with fluorosilane

Surfaces of hexagonal boron nitride (hBN) nanoparticles were modified with perfluorooctyl-triethoxysilane (FTS). Experiments were performed for 40–120min in 70–150°C range with FTS/hBN weight ratio in the range of 0.5–1.5. The products were analyzed by FT-IR, TGA, FESEM, HRTEM and EDX. Results of FT-IR analyses indicated that modification takes place in 80min at 150°C under reflux with a FTS/hBN ratio of 1.5. Presence of FTS on hBN nanoparticles was confirmed by the weight losses in TGA, and by TEM, TEM-EDX analyses.

Effect of Diluted Nano-Oil on the Anti-Wear and Friction Properties

Experimental work procedures on the anti-wear and friction properties were conducted to investigate the effect of nano-oil diluted with biodiesel fuel. In this work, an optimal composition (0.5 vol.%) of 70nm hBN nanoparticles was dispersed into SAE15W40 diesel engine oil by using sonication technique as a nano-oil. The homogenize nano-oil then was diluted by four difference percentages of B100 biodiesel fuel (5%, 10%, 15%, 20%). The anti-wear and friction tests were performed using four-ball tribometer according to the ASTM D-4172 standard. Result found that the addition of biodiesel fuel into homogenize nano-oil increases the coefficient of friction (COF) drastically by 25 ~ 96%, as compared with nano-oil and the wear rate also increase approximately by 9.68 ~ 19.50%.

The potential of hBN nanoparticles as friction modifier and antiwear additive in engine oil

An experimental investigation was conducted to investigate the potential of hexagonal boron nitride (hBN) nanoparticles as friction modifier and antiwear additive in engine oil. In this study, an optimal composition (0.5 vol.%) of 70 nm hBN nanoparticles was dispersed in SAE 15W-40 diesel engine oil by sonication technique. Sample was stabilized using 0.3 vol.% oleic acid as a surfactant. The tribological test was performed using a four-ball tribometer. Surface morphology and its chemical composition were carried out using a profilometer, Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDX). It was found that the optimized nano-oil could reduce the coefficient of friction and increase wear resistance, as compared with conventional diesel engine oil. Some adhesive and abrasive wear types were identified as predominant wear mechanisms.

Enhancing the Anhydrous Proton Conductivity of Sulfonated Polysulfone/Polyvinyl Phosphonic Acid Composite Membranes With Hexagonal Boron Nitride

Hexagonal boron nitride (h-BN) particles have attracted increasing interest due to mechanical properties, chemical stability, electrical features, thermal stability, and good lubrication property. In this work hexagonal boron nitride were used as inorganic fillers, which increase the mechanical and thermal stabilities of the membrane. The proton conducting polymer membranes were prepared by blending of sulfonated polysulfone, polyvinyl phosphonic acid, and boron nitride. Scanning electron microscopy indicated the homogeneous distribution of hBN nanoparticles in the polymer matrix. hBN increased the proton conductivity and in the anhydrous state the maximum proton conductivity was determined as 7.9 × 10−3 S/cm at 150°C for PVPA-SPSU-5hBN.

Improving Engine Oil Properties by Dispersion of hBN/Al<sub>2</sub>O<sub>3</sub> Nanoparticles

This paper provides oil properties study of conventional diesel engine oil enriched with hBN/Al2O3 nanoparticles. In this study, an optimal composition (0.5 vol.%) of hBN and Al2O3 nanoparticles separately dispersed in SAE 15W40 diesel engine oil by sonication technique. The oil properties were studied by measuring the Viscosity Index (VI), Total Acid Number (TAN), Total Base Number (TBN) and flash point temperature. The results reveal that the nano-oil with hBN nanoparticles could improves or at least maintain the key lubrication properties, though the TAN value is slightly increased. The results presented here may facilitate improvements in the conventional diesel engine oil performance.

Optimization of Tribological Performance of hBN/AL2O3Nanoparticles as Engine Oil Additives

The purpose of this study is to determine the optimal design parameters and to indicate which of the design parameters that are statistically significant for obtaining a low coefficient of friction (COF) with hexagonal boron nitride (hBN) and alumina (Al2O3) nanoparticles, dispersed in conventional diesel engine oil (SAE 15W40). Design of experiment (DOE) was constructed using the Taguchi method, which consists of L9 orthogonal arrays. Tribological testing was conducted using a four-ball tester according to ASTM standard D4172 procedures. According to the analysis of signal-to-noise (S/N) ratio and analysis of variance (ANOVA), COF and wear scar diameter were reduced significantly by dispersing several concentrations of hBN nanoparticles in conventional diesel engine oil, compared to without nanoparticles and with Al2O3 nanoparticle additive. Contribution of 0.5 vol.% of hBN and 0.3 vol.% of oleic acid, as a surfactant, can be an optimal composition additive in conventional diesel engine oil, to obtain a lower COF. In addition, the predicted value of COF by utilizing the levels of the optimal design parameters (0.5 vol.%hBN, 0.3 vol.% surfactant),as made by the Taguchi optimization method, was consistent with the confirmation test (average value of COF = 0.07215), which fell within a 95% confidence interval (CI).

A facile solid state reaction route towards nearly monodisperse hexagonal boron nitride nanoparticles

Nearly monodisperse hexagonal boron nitride (hBN) nanoparticles with low agglomeration degree were successfully synthesized via a modified solid state metathesis reaction route. It was found that sulfur was essential for preparing monodisperse hBN nanoparticles at 250 °C. However, when the temperature exceeded 300 °C, hBN nanoparticles with uniform size could also be quickly synthesized even without sulfur, and the yield was up to ∼65%. Furthermore, the experimental results were properly explained by a fast reaction and explosive dispersion mechanism, which was proposed according to the exothermal reaction between sulfur and NaN3 and the explosive decomposition of the latter. Besides, the good thermal stability and high specific surface area made the as-prepared hBN nanoparticles applicable in many areas.

Direct synthesis of hBN/MWCNT composite particles using spray pyrolysis

Abstract A spray-pyrolysis technique for the direct synthesis of multi-wall carbon nanotubes (MWCNTs) on a hexagonal boron nitride (hBN) matrix has been developed. Cobalt palladium (CoPd) nanoparticles, hBN nanoparticles, and ethanol were used as the catalyst, matrix, and carbon source, respectively. The materials were mixed by ultrasonication and then sprayed into a vertical tubular reactor at 900 °C under an argon flow of 2 L/min. As the aerosol passed through the reactor, the following processes occurred sequentially: solvent evaporation; formation of spherical particles composed of hBN and CoPd nanoparticles; catalytic decomposition of ethanol; and CNT growth on the surface of the CoPd nanoparticles. As a result, spherical-hairy particles were obtained, and both the hBN hexagonal phase and primary particle diameter were maintained during the reaction pathway because of the short residence time (1 s). The results showed that the spray-dried particle size and population of MWCNTs depended on the residence time within the heating zone and on the initial CoPd concentration. The novel synthesis technique described in this paper can be broadly applied to the production of various types of functional inorganic material/CNT composite particles.