Nanometric Diamond Research Articles

Sulfonated carbon nano-onion incorporated polyethersulfone nanocomposite ultrafiltration membranes with improved permeability and antifouling property

A novel, highly hydrophilic nanocomposite additive, sulfonated carbon nano onion (SCNO), was synthesized from nanometer diamond by thermal annealing, phenylation and sulfonation. To examine the effects of the highly sulfonated spherical nanofillers, they were incorporated into polyethersulfone (PES) to fabricate nanocomposite ultrafiltration (UF) membranes through nonsolvent induced phase separation (NIPS) method. SCNO nanoparticles and PES/SCNO nanocomposite UF membranes were characterized using different characterization techniques including Fourier transform infrared spectroscopy, X-Ray diffraction, scanning electron microscope, atomic force microscopy and water contact angle. The performance of the PES/SCNO nanocomposite UF membranes was investigated with a cross-flow filtration system. The water contact angle gradually declined from 87.9° to 31° when the SCNO content varied from 0 to 1.5 wt%. The pure water flux of the PES/SCNO-1.0 membrane with SCNO content of 1.0% was up to 163.64 kg·m−2·h−1, which was 236% higher than the pristine PES membrane, along with the highest flux recovery ratio of 93.4% with bovine serum albumin. Overall, the incorporated SCNO nanoparticles opened a novel path to enhance the hydrophilicity, permeability and antifouling property of the PES-based UF membrane.

Bimetallic iron-copper oxide nanoparticles supported on nanometric diamond as efficient and stable sunlight-assisted Fenton photocatalyst

Bimetallic iron and copper oxide nanoparticles (NPs) supported on hydroxylated diamond (D3) exhibits an improved activity for the heterogeneous Fenton phenol degradation under natural or simulated sunlight irradiation with respect to analogous monometallic samples or than analogous FeCu NPs on graphite, activated carbon and P25 TiO2 semiconductor. FeCu/D3 catalyst exhibits good recyclability and stability especially working at pH 6. Overall, the high activity of the Fe20Cu80(0.2 wt%)/D3 catalyst is mainly due to the combination of the high activity of reduced copper species decomposing H2O2 to HO· radical, while Fe2+ allows the regeneration of these reduced copper species.

Epitaxial diamond on Ir/ SrTiO3/Si (001): From sequential material characterizations to fabrication of lateral Schottky diodes

Advanced characterizations with combined analytical tools were carried out at the different stages of diamond heteroepitaxy on Ir/STO/Si (001) substrates. HRTEM and STEM-EELS revealed the presence of epitaxial nanometric diamond crystals after bias enhanced nucleation. UV Raman allowed estimating the diamond film quality and its strain at the early stages of heteroepitaxial growth. The crystalline structure and the strain within thick heteroepitaxial films were determined by XRD and CL investigations. A CL study of the cross-section provided the mapping of the dislocation network along the growth direction. Measurements performed on lateral Schottky diodes fabricated on a thick diamond film showed an excellent reproducibility on the substrate with a Schottky barrier height in good agreement with those obtained on homoepitaxial layers.

Nanometric diamond delta doping with boron

Diamond is desired for active semiconducting device because of it high carrier mobility, high voltage breakdown resistance, and high thermal diffusivity. Exploiting diamond as a semiconductor is hampered by the lack of shallow dopants to create sufficient electronic carriers at room temperature. In this work, nanometer thick, heavily boron doped epitaxial diamond ‘delta doped’ layers have been grown on ultra smooth diamond surfaces which demonstrate p type conduction with enhanced Hall mobilities of up to 120 cm2/Vs and sheet carrier concentrations to 6 × 1013 cm–2, thus enabling a new class of active diamond electronic devices. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Dyes decolorization using silver nanoparticles supported on nanometric diamond as highly efficient photocatalyst under natural Sunlight irradiation

Herein we report that silver nanoparticles supported on commercial diamond nanoparticles functionalized with hydroxyl groups (D3) is a cost-effective heterogeneous catalyst for the decolorization of different synthetic dyes (Methylene Blue, Orange II, Acid Red 1 or Rhodamine B) using H2O2 as oxidant under natural Sunlight irradiation. Importantly, the photocatalytic activity of Ag/D3 is higher than that of analogous catalysts based on Ag NPs supported on graphite or activated carbon and similar to that of costly Au/D3 catalyst or the benchmark Ag/TiO2 material. Ag/D3 stability was established by performing consecutive reuses, without observing either decrease of the catalytic activity or metal leaching, while particle size increase occurs in a low extent. Productivity tests allow determining a minimum TON for dyes and H2O2 of about 500 and 6000, respectively.

Mitigation of chemical wear by graphene platelets during diamond cutting of steel

The diamond cutting of transition metal alloys, particularly steel, is severely hindered by accelerated chemical wear of the tool. Recent experimental findings show that the presence of graphene platelets mitigates this problem. However, the specific mechanisms responsible for this wear mitigation are currently unknown. In this paper, molecular dynamics techniques are successfully used to identify these diamond tool wear mitigation mechanisms. A modified embedded atom method force field is first evaluated for its ability to accurately simulate the catalyzed graphitization of diamond in the presence of steel. This force field is then used to simulate nanometric diamond cutting of steel in the presence of a 1 or 3 layered graphene platelet. Coordination analysis of these simulations shows that the presence of the graphene platelet results in 34%–96% reduction in tool wear, when compared to the graphene-free cutting condition. This is attributed to the graphene platelet serving as a physical barrier protecting the tool cutting edge, and also as a sacrificial source for carbon transfer into the workpiece. Other mechanisms, such as platelet cleaving and interlayer sliding, are also observed. The reduction in tool wear reported by the simulations is comparable to the trends observed in prior experiments.

Porous diamond foam with nanometric diamond grains using Bias Enhanced Nucleation on iridium

Porous diamond foam exhibiting a three-dimensional structure was synthesized by applying prolonged Bias Enhanced Nucleation on iridium buffer layers. The Raman spectrum of this material recorded at 325nm looks very close to the signature obtained for detonation nanodiamonds. HRTEM investigations well confirm the presence of diamond crystals with nanometric size between 2 and 6nm. All these diamond nanocrystals form a three-dimensional structure very different from ultrananocrystalline diamond (UNCD) generally embedded in a graphitic matrix. According to its high specific surface area, such a 3D material may have promising applications for sensors.

Effect of pressure on the growth of boron and nitrogen doped HFCVD diamond films on WC–Co substrate

Boron and nitrogen compounds are added in the acetone/hydrogen gas mixture to deposit hot filament chemical vapor deposition (HFCVD) diamond films on the cobalt cemented tungsten carbide (WC–Co) substrate under the pressure of 1–4 kPa. The as‐deposited diamond films are characterized by field emission scanning electron microscope (FESEM), atomic force microscopy (AFM), X‐ray diffraction (XRD) spectroscopy and Raman spectroscopy. The results reveal that the surface morphology, growth rate, structure and quality of the diamond films vary with the pressure and the type of the impurity addition. The diamond grains tend to develop into the nanometer scale with the decrease of the pressure. However, adding of boron or nitrogen impurities in the gas mixture will weaken the nanocrystallization effect by reducing the carbon supersaturation. Density functional theory (DFT) calculations indicate that co‐adsorption of B and N containing radicals can favor the adsorption of CH3 on diamond (100) surface. Thus, at low pressure of 1 kPa, large grained cubic (100) facet diamond rather than typical nanometer diamond is produced for B–N co‐addition gas mixture. The present results appear to be useful to efficiently synthesize high quality doped diamonds with desirable properties for mechanical application. Copyright © 2015 John Wiley & Sons, Ltd.

나노결정질 다이아몬드가 코팅된 SiC 마모시험기 볼

Nanocrystalline diamond(NCD) coated SiC balls were applied in a ball-on-disk tribometer. After seeding in an ultrasonic bath containing nanometer diamond powders, 2.2 µm thick NCD films were deposited on sintered 3 mm diameter SiC balls at 600 o C in a 2.45 GHz microwave plasma CVD system. Bare ZrO2 and SiC balls were prepared for comparison as test balls. Tribology tests were performed in air with pairs of three different balls and mirror polished steel(SKH51) disk. The wear tracks on balls and disks were examined by optical microscope and alpha step profiler. Under the load of 3 N, the friction coefficients of steel against ZrO2, SiC and NCD-coated balls were between 0.4 and 0.8. After a few thousands sliding laps, the friction coefficient of NCD-coated balls dropped from 0.45 to below 0.1 and maintained thereafter. Under a higher load of 10 N or 20 N with a long sliding distance of 2 km, ZrO2 and SiC balls exhibited the similar friction coefficients as above. The friction coefficient of NCD-coated balls was less than 0.1 from the beginning and increased to above 0.1 steadily or with some fluctuations as sliding distance increased. NCD coating layers were found worn out after long duration and/or high load sliding test, which resulted in the friction coefficient higher than 0.1.

초경합금에 나노결정질 다이아몬드 코팅 시 금속 중간층의 효과

For the coating of diamond films on WC-Co tools, a buffer interlayer is needed because Co catalyzes diamond into graphite. W and Ti were chosen as candidate interlayer materials to prevent the diffusion of Co during diamond deposition. W or Ti interlayer of 1 μm thickness was deposited on WC-Co substrate under Ar in a DC magnetron sputter. After seeding treatment of the interlayer-deposited specimens in an ultrasonic bath containing nanometer diamond powders, 2 μm thick nanocrystalline diamond (NCD) films were deposited at 600oC over the metal layers in a 2.45 GHz microwave plasma CVD system. The crosssectional morphology of films was observed by FESEM. X-ray diffraction and visual Raman spectroscopy were used to confirm the NCD crystal structure. Micro hardness was measured by nano-indenter. The coefficient of friction (COF) was measured by tribology test using ball on disk method. After tribology test, wear tracks were examined by optical microscope and alpha step profiler. Rockwell C indentation test was performed to characterize the adhesion between films and substrate. Ti and W were found good interlayer materials to act as Co diffusion barriers and diamond nucleation layers. The COFs on NCD films with W or Ti interlayer were measured as less than 0.1 whereas that on bare WC-Co was 0.6~1.0. However, W interlayer exhibited better results than Ti in terms of the adhesion to WC-Co substrate and to NCD film. This result is believed to be due to smaller difference in the coefficients of thermal expansion of the related films in the case of W interlayer than Ti one. By varying the thickness of W interlayer as 1, 2, and 4 μm with a fixed 2 μm thick NCD film, no difference in COF and wear behavior but a significant change in adhesion was observed. It was shown that the thicker the interlayer, the stronger the adhesion. It is suggested that thicker W interlayer is more effective in relieving the residual stress of NCD film during cooling after deposition and results in stronger adhesion.

Study on Ni-P-Nanometer Diamond Composite Electroless Plating for 2A12 Aluminum Alloy

On the basis of electroless Ni-P plating, the technique of electroless Ni-P-nanometer diamond composite plating for 2A12 aluminum alloy was studied. The table of L9 (34) of orthogonal design was adopted in the experiment. The optimal formulation of plating bath for 2A12 aluminum alloy was determined. The effect of bath composition on deposition rate and adhesion strength was studied. The results show that the order of marked factors on deposition rate from large to small is nanometer diamond, sodium acetate, nickel sulfate hexahydrate and sodium hypophosphite in turn, while for adhesion strength is nanometer diamond, sodium acetate, sodium hypophosphite and nickel sulfate hexahydrate. The optimal plating formulation are consisted of nanometer diamond (2g/L), NiSO4•6H2O (30g/L), NaH2PO2•H2O (30g/L) and CH3COONa (15g/L), which is operated at 80~85°C, pH (4.5). The microstructure of coating plated with optimal process is cellular structure, which is homogeneous, compact and good brightness, and its deposition rate is 17.0μm/h.

Influence of cubic nanostructure additions on the properties of electroless coatings

In this research, the influence of co-deposited within nickel-phosphorus matrix cubic nano- and micro-sized particles (nanodiamond and micron cubic boron nitride) on the properties of the composite coatings was investigated. Nanometer diamond was synthesised by using the detonation method. It is a kind of materials with properties of diamond and nanometer particle. High phosphorus electroless nickel bath was used to prepare electroless nickel composite coatings from a suspension. In order to characterise the deposits, their structure, morphology and hardness were analysed. The incorporation of particles has a marginal influence on the composition. The influence of thermal processing of the samples on the coating properties was investigated. The highest microhardness, the superior corrosion and wear resistance of the nickel-phosphorus-nanodiamond composite coating was obtained by heat-treated samples.

Diamond nucleation in low electron temperature CH 4/H 2 plasma

Nucleation of diamond crystal is observed on a surface of fine diamond particles of micron meters attached to a nickel plate placed in methane–hydrogen plasma. The electron temperature T e in the plasma is quite important for the nucleation. When T e is reduced to ∼0.4 eV, we observed an appearance of nanometer diamond nucleation on the surface of the fine diamond particles. The size and the number of nucleation cite increase with the deposition time with average growth rate of ∼10 nm/h.

Synthesis and properties of electroless Ni–P–Nanometer Diamond composite coatings

Nanometer Diamond (ND) was synthesized by using the detonation method. It was a kind of materials with properties of diamond and nanometer particle. The Ni–P–ND composite coating was prepared from a suspension of diamond nanoparticles in electroless bath. The tribological properties, hardness and corrosion behaviours of the composite coating on medium carbon steels were investigated. The Ni–P–ND composite coating exhibits not only high wear resistance but also low friction coefficient compared with the Ni–P composite coating. The highest microhardness of the Ni–P–ND composite coating was obtained by heat treated at 673 K. The corrosion resistance of Ni–P–ND composite coating is superior to that of Ni–P coating. The mechanisms of improvement of the tribological and electrochemical properties of the electroless composite coating are also discussed.

EFFECTS OF HYDROGEN GAS FLOW RATIO ON THE QUALITY OF NANO-DIAMOND FILMS

In this paper, we studied the effects of hydrogen gas flow ratio of [H2]/[N2 + CH4 + H2] on the quality of nanometer diamond (nano-diamond) films prepared by microwave plasma enhanced chemical vapor deposition method. Nano-diamond films were deposited on the silicon substrates from a gaseous mixture of nitrogen, methane and hydrogen. The experimental results show that if only using a gaseous mixture of nitrogen and methane, although we can obtain nano-diamond films with a grain size of about 5nm, the diamond films contain much non-diamond components. With hydrogen addition, and with increasing the hydrogen gas flow ratio from 1 to 10%, the non-diamond components in the films are significantly reduced and the grain size of the films increases from 5nm to 60nm. However optical transmittance of the films increases with increasing hydrogen gas flow ratio from 1 to 7% because of an improvement of film quality, and then decreases with further increasing hydrogen gas flow ratio owing to the increase of film roughness.

Anti-friction properties of Cu10Sn-based composite containing nanometer diamond particles

Cu10Sn-based composite containing nanometer diamond was prepared for investigating the effect of nanometer diamond on reducing friction of the composite. A good distribution of nanometer diamond in the matrix of Cu10Sn was obtained by a special process. The friction test was carried out with a hardened AISI 52100 steel ring rotating against block-shaped samples. The results showed that the composite has a higher hardness and a lower bend strength compared with the reference Cu10Sn alloy. Under a normal pressure of 4.0 MPa and a range of sliding speed from 0.26 to 1.56 m/s, the friction coefficient of the composite is almost constant and much lower than that of Cu10Sn. Based on the observations of worn surfaces and the morphology of wear debris, it is indicated that the motion mode of quasi-spherical wear debris containing nanometer diamond is the main factor for the reduction of friction coefficient.

Effects of direct current and pulse-plating on the co-deposition of nickel and nanometer diamond powder

Nickel and nanometer-diamond powder have been successfully co-deposited on Cu alloy by the direct current and pulse plating methods. The variables investigated within this research work include the concentration of diamond powder in the plating solution, current density (d.c.), current frequency (pulse plating), plating temperature, plating time, and stirring speed during plating processes. The microhardness of the co-deposited layer is increased with increasing concentration of diamond powder in the plating solution. The surface roughness is increased as well. The microhardness value of the specimen treated with 40 g/l diamond powder concentration can reach 611 HV using the method of pulse plating. The stirring speed below 300 rpm and plating temperature ranging from 30 to 50°C are found to be suitable for Ni–diamond composite plating . The friction coefficient , μ , of the Ni–20 g/l diamond co-deposition specimen is about 0.16, which is much lower than that of pure Ni-plated layer ( μ =0.44).

Effects of cemented carbide surface pretreatment in combustion flame chemical vapour deposition of diamond

Effects of different pretreatment procedures on WC–6%Co surface modification and some properties of diamond coating deposited by combustion flame CVD on the pretreated surfaces have been systematically studied. The pretreatment procedures examined were: action of an oxidising oxygen/acetylene flame at 1000°C, scratching with diamond (D) particles or their mixture with iron (D+Fe) in an ultrasonic bath, and seeding with a nanometer diamond colloidal suspension. An acid treatment was always included in the pretreatment sequence. The oxidising flame was found to produce fine-grained W, W 2C and WO 2, resulting in an increased diamond particle density and a lower coating roughness, and leading to a relatively smooth and adherent diamond coating. However, the products of WC oxidation were detectable only if Co had been removed from the substrate surface prior to the action of flame. Otherwise, compounds of Co with P and O were formed, making a skin on the surface, which hindered action of the flame on WC. The acid treatment was found to remove Co effectively from the surface. Seeding resulted in a good coverage of the substrate surface with nano-particles of diamond, leading to a maximum diamond particle density, adhesion improvement and minimum coating roughness. Scratching with D+Fe mixture produced maximum roughness of both substrate and diamond coating surface, as well as low adhesion, while scratching with D particles showed a similar but smaller effect. Minimum surface roughness and maximum adhesion of the diamond coating were obtained for the substrate pretreated by oxidising flame, followed by the acid action and seeding with diamond nano-particles.