Concentrations Of Diamond Nanoparticles Research Articles

Ionic liquid stabilized nanoparticle additive in a steel-ceramic contact for extreme pressure application

This study presents and discusses the friction, wear and extreme pressure behavior of nanoparticles suspended in a gear base oil. Zero, 0.5, 1 and 2 %wt diamond and Zinc Oxide (ZnO) nanoparticles were separately dispersed in base stock and stabilized using a phosphonium ionic liquid. A rotary alumina ceramic ball on 20MnCr5 gear steel disc configuration was used to quantify the tribological performance of the formulated nanofluids. The results showed that the ionic liquid stabilizer in the base stock bonded to the surface of the disk resulted in the best anti-friction behavior but was accompanied by increased wear. The unique structure of diamond nanoparticles produced the best anti-wear behavior. Both diamond and ZnO nanoparticles stabilized with ionic liquid were effective in preventing scuffing. Thus, the nanoparticles have potential to be extreme pressure additives for gear oil applications. All concentrations of diamond nanoparticles and ZnO nanoparticles resulted in smoother surfaces after testing due to the nanoparticles acting as three body wear polishing agents.

Structure and morphology of composite coating of chromium with diamond nanoparticles on sintered steels

Electrochemical chromium coatings modified with diamond nanoparticles (ND) were deposited on sintered steel materials obtained from iron powder and ultrafine graphite powder. The diamond nanoparticles were produced by detonation synthesis. Their average size is 6 nm. The sintered steel consisted of 0.2, 0.4, 0.6 and 0.8%C (added in the form of graphite) by weight. The produced composite coatings consisting of Cr + ND were compact, tightly adhering to the substrate, with thickness of about 25–35 μm. The surface morphology and microstructure of the coatings were investigated by SEM and EDS analyzes. The main objective of the study was to explore the presence of ND in the coating by the X-ray photoelectron spectroscopy and the impact of the ND concentration in the electrolyte on the presence of the diamond nanoparticles in the coating. The spectra of the C1s photoelectronic line were obtained, the sp3/sp2 ratio and the sp3 + sp2 sum were determined electronically on the surface of the coatings (depth 10 nm). The Cr2p photoelectronic line spectra were also obtained. The coatings were deposited from electrolytes with ND concentrations of 10, 25 and 40 g/l. A diamond-like phase has been found in coatings obtained at concentrations of diamond nanoparticles in the electrolyte of 25 and 40 g/l. The sp3/sp2 ratio with a value equal to or greater than 1.2 is an indication of the presence of a diamond-like phase in the coatings and the ratio depends on the concentration of ND in the electrolyte.

Adhesive Pull and Shear Strength of Epoxy Nanocomposite Coatings Filled with Ultradispersed Diamond

In this work, epoxy diane oligomer ED-20 is used to form nanocomposite materials, polyethylene polyamine is used as a hardener, ultradispersed diamond with a particle size of 4–6 nm is used as a filler. The epoxy diane resin ED-20 was heated to 353 K. Then the ED-20 oligomer and the nanofiller were subjected to hydrodynamic mixing and subsequent ultrasonic treatment of the obtained composition. The effect of the concentration of diamond nanoparticles on the adhesion properties of composites was studied. The adhesion pull strength of materials was studied by measuring breaking stresses of cylindrical specimens glued by the nanocomposite adhesive. The adhesive shear strength was evaluated by the breaking stress of the lap joints of flat metal specimens glued by the nanocomposite adhesive. In both types of specimens, the glued sections had the same area. It has been found that the incorporation of nanoparticles in the concentration from 0.010 to 0.025 parts by weight per 100 parts by weight of ED-20 epoxy oligomer yields the adhesive pull strength of 25.0–26.3 MPa. The optimal concentration increases the latter value by a factor of 1.5 (to 34.3 MPa) and the adhesive shear strength – by a factor of 1.3 (to 10.8 MPa). The further increase in the concentration (0.075–1.0 parts by weight) is shown to deteriorate the adhesion strength. The nanocomposite coating–metal substrate bond breaking surface has been investigated. It is experimentally proved that the coatings with the cohesive nature of failure have the maximum adhesive pull strength, while those with the mixed (adhesive-cohesive) mode of failure exhibit an improved adhesive shear strength.

Impact of diamond nanoparticles on neural cells

Diamond nanoparticles (DNPs) are very attractive for biomedical applications, particularly for bioimaging. The aim of this study was to evaluate the impact of DNPs on neural cancer cells and thus to assess the possible application of DNPs for these cells imaging. For this purpose, the neuroblastoma SH-SY5Y cell line was chosen. Cells were cultured in medium with different concentrations (15, 50, 100 and 150 μg/ml) of DNPs. After 48 h of incubation, cell metabolic activity was evaluated by the XTT assay. For assessment of cellular metabolic activity, cells were also cultured on differently terminated nanocrystalline diamond (NCD) coatings in medium with 150 μg/ml of DNPs. Cell adhesion and morphology were evaluated by brightfield microscopy. Diamond nanoparticle internalization was determined by confocal microscopy. The obtained results showed that low concentrations (15, 50 and 100 μg/ml) of nanoparticles did not significantly affect the SH-SY5Y cell metabolic activity. However, a higher concentration (150 μg/ml) of DNPs statistically significantly reduced SH-SY5Y cell metabolic activity. After 48 h incubation with 150 μg/ml DNPs, cell metabolic activity was 23% lower than in medium without DNPs on standard tissue culture polystyrene.

Dielectric Properties of Nematic Liquid Crystal Modified with Diamond Nanoparticles

In the present study, the influence of diamond nanoparticles (DNPs) on dielectric properties of nematic liquid crystal (LC) E7 from Merck has been considered. It is established that the insertion of DNPs leads to an increase in the dielectric constant ε', as well as to a significant change in the electric conductivity σ of the LC. The growth of ε' with the concentration of DNPs, CDNP, is mainly caused by a contribution of the DNP permittivity to the effective permittivity of the composite. The character of the σ(CDNP) curves depends on the ionic purity of LC E7: for the samples based on pure E7, an increase of the electric conductivity with the concentration of DNPs is detected, whereas the reverse trend is observed for the samples containing impure E7. This behavior is attributed to the competitive adsorption and desorption of ions on/from the surface of DNPs and the ion transfer along the percolation network of theseparticles.

Electrophoretically Fabricated Diamond Nanoparticle-Based Electrodes

Dimensionally stable, high surface area support for a possible direct methanol fuel cell application was fabricated from commercial diamond nanoparticles through electrophoretic deposition onto silicon wafer substrates, and their electrochemical characteristics were examined by employing inorganic redox probes such as and . As-received diamond nanoparticles were purified by refluxing in an aqueous nitric acid solution, and the product was characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, prompt gamma-ray neutron activation analysis, Raman spectroscopy, electron energy loss spectroscopy, and transmission electron microscopy techniques. Electrophoretically deposited diamond nanoparticle layers of uniform thickness were obtained by controlling experimental parameters, such as applied voltage, deposition time, and the concentration of diamond nanoparticles in the suspension. Platinum nanoparticles were electrodeposited onto these diamond nanoparticle layers (Pt/DNP) by step and sweep potential method. Their structural and morphological characterizations were made by using scanning electron microscopy and energy-dispersive X-ray analysis. The electrochemical activity of Pt/DNP toward methanol oxidation was studied. The present study paves a way to fabricate ultrathin, uniform, high surface area, and dimensionally stable diamond electrodes in a controllable fashion. This type of deposited diamond nanoparticle layers may be considered as catalyst support material for fuel cell applications.