New Abrasive Coatings: Abraded Volume Measurements in Ceramic Ball Production

Technological progress in hybrid bearings developed high wear and abrasion resistant materials for rolling elements. The manufacturing process of bearing balls presents new challenges, as nowadays, it requires time-consuming and costly processes. In this frame, the bearing manufacturing industry is demanding improvements in materials, geometry, and processes. This work aims to investigate new abrasive coatings for grinding wheels for Si3N4 ball manufacturing. Tribological pin on disk tests are performed on samples of grinding materials (disk) versus a Si3N4 ball (pin). Two samples of specimens coated with an electrodeposited diamond and diamond-reinforced metal matrix composite are examined to measure the abrasion rate and the wear resistance of Silicon Nitride Si3N4 balls, considering the influence of sliding speed and the effect of coating deposition on diamond particle density and granulometry. The measurements estimated the specific wear coefficient k, the height wear surface h, and the wear rate u of the Si3N4 balls. The results pointed out that by increasing the sliding speed, the abraded volume increases for both the coatings. The parameters affecting the abrasion effectiveness of both the coatings are the surface roughness, the abrasive particle dimension, and the sliding speed.

Improved Hg2+ photocatalytic reduction over g-C3N4 nanosheets decorated with mesoporous Mn3O4 nanoparticles

The purpose of this investigation was to construct amended mesoporous Mn3O4/g-C3 N4 photocatalysts of various loadings of mesoporous Mn3O4 nanoparticles (1,2,3 and 4 wt%) for reinforced remediation of mercury ions (Hg2+) under visible light illumination. It was performed via decorating g-C3N4 nanosheets with finite portions of the prepared mesoporous Mn3O4 NPs by employing hard and soft templates. The optimized 3 wt% Mn3O4/g-C3N4 heterojunction gained confined bandgap (2.24 eV) as well as great surface area (140 m2 g -1) that support the application of such heterojunction for efficacious removal of Hg2+ under visible light. Morphological examination elucidated that the dispersed Mn3O4 NPs over g-C3N4 nanosheets were of spherical shape with particle dimension of 10-15 nm. Hg2+ was removed significantly over the formed Mn3O4/g-C3N4 nanocomposites when related to the pure materials (Mn3O4 NPs and g-C3N4). It was confirmed that Mn3O4 content, incorporated to g-C3N4 nanosheets, largely influenced the efficiency corresponding to the Hg2+ photoreduction such that appropriating 3 wt% Mn3O4 was capable of accomplishing complete removal of Hg2+ whereas, pure g-C3N 4was able to accomplish the same process by the efficiency of 15% after illumination for 60 min. Similarly, fast rate of Hg2+ photoreduction was accessed when 3% Mn3O4/g-C3N4 nanocomposite (485 µmol g–1 h–1) was administered while the photoreduction reaction was very slow with smaller rate magnitudes when pure g-C3N 4(82 µmol g -1 h -1) or pure Mn3O4 NPs (120 µmol g -1 h -1) were adopted. The powerful Hg2+ removal over the established heterojunctions can basically be associated with the larger attained surface area as well as the declined bandgap. Besides, the great dispersion of the small-sized Mn3O4 NPs and the mesoporous structure of the formed heterojunctions participated significantly in efficient Hg2+ removal. The improved characteristics of the prepared heterojunctions led to strong absorption of visible light and fast transference of reactant species, leading to enhanced photocatalytic efficiency. Recyclability experiments demonstrated that neither the photocatalytic performance nor the structure of the mesoporous Mn3O4/g-C3N4 heterojunction was altered after being reused for Hg2+ removal from aqueous solutions.

High coercivity SmCo5 synthesized with assistance of colloidal SiO2

SmCo5 is one of the most promising candidates for achieving a hard magnet with a high coercivity. Usually, composition, morphology, and size determine the coercivity of a magnet, however, it is challenging to synthesize phase pure SmCo5 with optimal size and high coercivity. In this paper, we report on the successful synthesis of phase pure SmCo5 with spherical/prolate spheroids shape. Size control is obtained by utilizing colloidal SiO2 as a template preventing aggregation and growth of the precursor. The amount of SiO2 nanoparticles (NPs) in the precursor tunes the average particle size (APS) of the synthesized SmCo5 with particle dimension from 740 to 504 nm. As-prepared pure SmCo5 fine powder obtained from using 2 ml SiO2 suspension possesses an APS of 625 nm and exhibits an excellent coercivity of 2986 kA m−1 (37.5 kOe) without alignment of the particles prior to magnetisation measurements. Comparing with a reference sample prepared without adding any SiO2 NPs, an enhancement of 35% of the coercivity was achieved. The improvement is due to phase purity, stable single-domain (SSD) size, and shape anisotropy originating from the prolate spheroid particles.

Influences of liquefied lignin content on the properties of waterborne polyurethane prepared with different chain extenders

Waterborne polyurethane resins (WPUs) were prepared from polytetramethylene ether glycol (PTMG) and PTMG/polyhydric alcohol liquefied lignin (LL) with isophorone diisocyanate (IPDI), and ethylenediamine (EDA) and 1,4-butanediol (1,4-BD) were used as chain extenders. The effects of LL and the kind of chain extender on the properties of the WPU suspensions and dried films were studied. WPU suspensions prepared with PTMG/LL as the polyol had higher viscosity and larger average particle dimension than those with PTMG alone. WPU films prepared with EDA as the chain extender had higher tensile strength with less tensile deformation. LL can enhance the stiffness of WPU films, but the breaking deformation decreases. Dynamic mechanical analyzer (DMA) results showed that the main effect of LL was reduced thermal activity of the soft segment. Thermogravimetric analyzer (TGA) results showed WPU films prepared with EDA as the chain extender had better heat-resistance than those with 1,4-BD.

Facile Eco-compactable Design for Synthesis and Characterizing of Silver Nanoparticles

Background: The synthesis of metal Nanoparticles is a growing area of research interest due to its potential in the applications and development of advanced technologies. Here we have stressed on the Facile green synthesis approach that connects the nanotechnology and biotechnology. Methods: The method involves use of biological reducing agent cum stabilizing agent (capping agent). A comparative account of particle dimension and surface properties of the synthesized nano particles using Broccoli (Brassicaoleracea var.italica) extract is also presented. Results: The reduction process used in the synthesis was simple and convenient to handle and monitored by UV--Vis spectroscopy showing the absorbance maxima of various samples at 322nm, 496nm and 536nm using different solvents. The presence of active proteins and phenolic groups present in biomass before and after reduction was identified by FTIR. Conclusion: The crystalline morphology and size of the Nanoparticles were examined by TEM, SEM and X-ray diffraction studies, which showed the average particle size of Silver Nanoparticles in the range of 40- 50 nm as well as revealed their FCC structure.

A REVIEW OF DEPOSIT VELOCITY PREDICTION METHODS FOR MEDIUM PARTICLE SIZE SLURRIES IN PIPES

Methods of predicting the deposit velocity for wide particle size slurries with maximum particle size up to about 1 mm and maximum d50 size around 0.3 mm are outlined. These slurries generally possess non-Newtonian properties, typically modelled as Bingham plastics, and typically flow pseudo-homogeneously in turbulent flow down to the deposit velocity. Because they flow pseudo-homogeneously, pressure gradient prediction is relatively easy once a suitable operating velocity is selected. Consequently, the deposit velocity is the most important parameter as it determines the operating velocity. Beginning with Durand and Condolios [6], the historical development of the major methods for predicting the deposit velocity for mono-size particles in water are first reviewed, and their advantages and limitations discussed. Methods of extending predictions to mono-size particles in viscous Newtonian fluids are then reviewed. Next, prediction techniques relevant to deposition are reviewed for non-Newtonian slurries. These include prediction of the transition velocity between laminar and turbulent flow, and the critical pressure gradient required to prevent deposition under laminar flow conditions. Finally, these prediction techniques are combined to apply to minus 1 mm, wide size distribution, viscous slurries, commonly encountered in the mining industry. Two deposit velocity prediction techniques for these types of slurries are discussed. The first technique, based on determining the inherent viscosity of the slurry and assuming the weighted mean particle size of the total slurry represented the relevant coarse particle dimension, was found to predict performance in an operating 593 mm ID pipeline. The second technique, based on assuming the minus 75 µm portion represented the “carrier” fluid and assuming the median size of the plus 75 µm portion represented the relevant coarse particle dimension, was found to give very good predictions of the observed deposition trends of Goosen and Paterson [8] for a minus 300 µm gold tailings tested in 100 mm, 152 mm and 242 mm test loops.

Scrutiny of Gold Surface Plasmonic Nanoparticles Embedded in Various Substrates used for Enhancing Solar Cell's Efficiency

The objective of this paper is to read the various substrates which are mounted on Gold plasmonic nanoparticle and how they enhance the efficiency of a solar cell. With the help of MIE scattering software, we found the different type of light inclusion and light scattering by Gold nanoparticles mounted on various substrates of a solar cell. The second objective of this paper is to learn the outcome of nanoparticle dimension and standard deviation on light scattering and absorption. The process of this work can be shortened as follows: The literature review on surface plasmons and how effects solar cell efficiency is done. The software MIEPLOTV4305 and how it is used for the research work were studied. Scrutiny of gold samples with different mediums and comparing the variations in peak wavelength using MIE PLOT software and graphs were placed. The outcome of particle dimension and standard deviation on CSCATTERING, CABSORPTION, QSCATTERING, and QABSORPTION were done.

TiO2 and N-TiO2 Sepiolite and Zeolite Composites for Photocatalytic Removal of Ofloxacin from Polluted Water

TiO2 sepiolite and zeolite composites, as well the corresponding N-doped composites, synthesized through a sol–gel method, were tested for the photocatalytic degradation of a widespread fluoroquinolone antibiotic (ofloxacin) under environmental conditions. The catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS) analyses. A complete drug degradation occurred in 10–15 min in the presence of both TiO2 sepiolite and zeolite catalysts, and in 20–30 min with the N-doped ones. Sepiolite proved to be a better TiO2 support compared to the most common zeolite both in terms of adsorption capacity and photocatalytic efficiency in pollutants degradation. The influence of nitrogen doping (red shift from 3.2 to 3.0 eV) was also investigated. Although it was blurred by a marked increase of the particle dimension and thus a decrease of the specific surface area of the doped catalysts, it allowed a faster drug removal than direct photolysis. The photochemical paths and photoproducts were investigated, too.

Quantities Directly Measurable by Scattering

In this chapter we note that solution scattering data can be divided into four regions. At zero scattering angle, the scattering provides information on molecular weight of the particle in solution. Beyond that, the scattering is influenced by the radius of gyration. As the scattering angle increases, the scattering is influenced by the particle shape, and finally by the interface with the particle and the solution. There are a number of important invariants that can be calculated directly from the data including molecular mass, radius of gyration, Porod invariant, particle volume, maximum particle dimension, particle surface area, correlation length, and volume of correlation. The meaning of these is described in turn along with their mathematical derivations.