Amount Of SiC Nanoparticles Research Articles

SiC nanoparticles incorporation in electroless NiP-Graphene oxide nanocomposite coatings

The presence of SiC nanoparticles within the Graphene oxide (GO) incorporated electroless deposited NiP layers (NiP-GO) on carbon steel substrate was studied in this work. The effect of co-deposition of GO nanoplatelets and/or SiC nanoparticles on the morphology and structure of the heat-treated NiP coatings were investigated by scanning electron microscope and X-ray diffraction, respectively. The results revealed that the heat-treated NiP and NiP–SiC coatings consisted of Ni and Ni3P phases, whereas the NiP-GO also contains the intermediated Ni2P and Ni12P5 metastable phases due to the incomplete precipitation of Ni3P. Such metastable phases are significantly decreased by the incorporation of SiC nanoparticles in NiP-GO coatings. The mechanical properties of the coatings were characterized by microhardness measurement and “pin on disk” wear test. The corrosion tests were conducted in aqueous 3.5 %wt NaCl using electrochemical measurement for Ni–P, NiP-GO, NiP–SiC, and NiP-GO-xSiC coatings. By co-deposition of SiC nanoparticles, the hardness of NiP-GO is significantly increased and the wear loss is reduced, especially at a high sliding distance during the wear test. The corrosion behavior of the NiP-GO coatings containing different amounts of SiC nanoparticles has been investigated.

Parametric optimization of the aluminium nanocomposites wear rate

The optimization of wear rate of the nanocomposites with A356 aluminium alloy matrix, reinforced with silicon carbide nanoparticles, was performed through the analysis of the following influences: wt% of the reinforcement, normal load and sliding speed. The nanocomposites were produced by the compocasting process with mechanical alloying preprocessing (ball milling). Three different amounts of SiC nanoparticles, with the same average size of 50 nm, were used as reinforcement, i.e. 0.2, 0.3 and 0.5 wt%. Tribological tests were performed on block-on-disc tribometer (line contact) under lubricated sliding conditions, at two sliding speeds (0.25 and 1 m/s), two normal loads (40 and 100 N) and at sliding distance of 1000 m. Analysis of variance (ANOVA) was applied to determine the influence of different parameters on wear value of tested nanocomposites. It was noticed from ANOVA analysis that normal load, with 33.39%, is the most significant factor affecting the wear rate of nanocomposites. The amount of reinforcement, with 28.90%, also has a significant influence on the wear rate, while the influence of sliding speed, with 23.82%, is smaller. It was found that the prediction of wear rate, by using regression model and Taguchi analysis, were close to the experimental values.

Low-temperature pressureless sintering of Al2O3-SiC-Ni nanocermets in air environment

This paper introduces a simplified method for low-temperature pressureless sintering of Al2O3-Ni-SiC nanocermets in air environment. In this method, a thin and continuous Ni shell was coated on the surface of Al2O3 particles using electroless deposition method. The composite powders were subsequently compressed to prepare bulk specimens. By preventing the ceramic particles from direct contact during the densification of green specimens, sintering temperature of cermet materials was reduced from that of Al2O3 (> 1400 °C) to the range of Ni solid-phase sintering temperature. Furthermore, dissolution of a low amount of phosphorus in the composition of Ni coatings caused the further decrease of the sintering temperature to 800 °C. At such low temperatures, pressureless sintering of the cermets in the air environment was successfully performed instead of the common hot pressing process in a reducing atmosphere. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD) characterizations indicated that the microstructure of such sintered samples consists of a continuous Ni network surrounding Al2O3 grains, without any structural defects or Ni oxidation. Furthermore, mechanical properties of the cermet materials were improved through reinforcement of the continuous Ni network by different amounts of SiC nanoparticles. The results showed that Al2O3-Ni-5 wt% SiC nanocermets sintered at 800 °C obtain the highest compressive strength of 242.5 MPa, hardness of 56.8 RA, and the lowest wear weight loss of 0.04 mg/m.

Enhanced thermoelectric properties of nano SiC dispersed Bi2Sr2Co2Oy Ceramics

The thermoelectric properties of Bi2Sr2Co2Oy + x wt% nano SiC (x = 0.00, 0.025, 0.05, 0.1, 0.2, and 0.3) prepared by the solid-state reaction method were investigated from 300 K to 923 K. The resistivity can be reduced effectively by adding a small amount of SiC nano particles, which is attributed to the increase of the carrier concentration. At the same time, the Seebeck coefficients can be improved effectively due to the energy filtering effect that low energy carriers are strongly dispersed at the interface between the SiC nano particles and the matrix. The decrease of thermal conductivity is due to the increase of the scattering ability of the phonons by the SiC nanoparticles distributed at the boundary of the matrix. As a result, the Bi2Sr2Co2Oy + x wt% SiC composites exhibit better thermoelectric properties. The maximum ZT value 0.24 is obtained when x = 0.05 at 923 K. Compared with the sample without SiC nano particles, the ZT value is increased by about 59.7%.

Tribological properties of PI-SiC nanocomposite prepared by hot dynamic compaction

Wear resistance of polyimide/SiC (PI-SiC) nanocomposite prepared by hot dynamic compaction was investigated in this article. Mechanically milled micro-sized PI with different amounts of SiC nanoparticles (SiCnp), 0, 2.5, 5, 7.5, and 10 vol%, were used to fabricate the samples. Dynamic compaction was conducted at the strain rates of about 103s−1. The microstructural and mechanical behaviors of the samples, such as microhardness and stress–strain curves, were also investigated. The results showed improvement in the microhardness and compressive strength of the material. The results also revealed reduction in wear resistance as SiC reinforcing particles increased. The microstructural study of the worn surfaces indicated that the abrasive and delamination were the dominant wear mechanisms.

An Investigation of Parameters Involved and Defects in the Fabrication of Al–SiC Nanocomposite Using Hot Extrusion Technique

In the present work, some parameters including temperature, pressure, boundary conditions (lubricant and friction), and also defects during hot extrusion technique (HET) of specimens were studied and their reasons were analyzed. The nanocomposite powders were prepared by a powder metallurgy route consisting of mechanical milling, cold pressing, and HET. Micron-sized Al with different amounts of SiC nanoparticles, 0, 1.5, and 3 vol%, were used to fabricate the specimens. The physical and mechanical properties of the extruded samples such as density, microhardness, tensile strength, and also the microstructure of the materials were evaluated. It was found that by increasing the nanoparticle contents, microhardness and tensile strength increased and ductility declined. The right and appropriate design of die, using foil or aluminum cans, proper lubricant, and extrusion rate were important parameters to be controlled to obtain minimum defects. The results showed that the temperature of 550 °C was more appropriate towards achieving superior tensile strength than at 500 °C and better surface finish than at 500 and/or 600 °C.

Fabrication of NanoSiC-Reinforced Al2024 Matrix Composites by a Novel Production Method

In this paper, flake powder metallurgy technique is described for fabricating near-net-shape SiC nanoparticle-reinforced Al2024 matrix composites. The effect of the particle size on the flake Al2024 matrix powders and the amount of SiC nanoparticles in the particle distribution, microstructure, relative density, and hardness of SiC nanoparticle-reinforced Al2024 matrix composites were investigated. The flake Al2024 matrix powders were mixed with three different as-received Al2024 powders particle sizes by ball milling. Microstructural characterization revealed a flake-like microstructure and dispersed SiC nanoparticles between the Al2024 matrix powders with grain boundaries containing sufficient area for the reinforcement particles. The hot pressed density increased as the matrix size decreased due to the small frictional forces observed between the fine flake particles. The hardness of Al2024/SiC nanocomposites increased as the size of the Al2024 matrix powders decreased.

Microstructure evolution and mechanical properties of SiC nanoparticles reinforced magnesium matrix composite processed by cyclic closed-die forging

Magnesium composites containing different amounts of SiC nanoparticles were processed by a two-step cyclic closed-die forging (CCDF), which was carried out at 400°C for 3 passes (1st-CCDF) and further at 300°C for 2 passes (2nd-CCDF). Microstructure evolution and mechanical properties of the composites were investigated. After processing, the average grain size is significantly refined to ~2.5μm, and the morphology exhibits a flow-lined feature. The β-Mg17Al12 phases in the as-cast alloy dissolve completely after 1st-CCDF, and then precipitate out with an average size of ~650nm during 2nd-CCDF. After CCDF, the as-cast SiC clusters are uniformly dispersed as separate particles, and the yield strength and ultimate strength of the composites reach 258MPa and 365MPa, respectively. The ductility of the composites is enhanced after 1st-CCDF but decreased after 2nd-CCDF, which is in accordance with the observed fracture surfaces. From the perspective of strength and ductility, the optimal content of SiC is 0.5wt%.

Tribological properties of Al7075-SiC nanocomposite prepared by hot dynamic compaction

Wear resistance of Al7075-SiC nanocomposite prepared by hot dynamic compaction was investigated in this article. Mechanically milled micro-sized Al7075 with different amounts of SiC nanoparticles (SiCnp), 0, 5, and 10 vol%, were used to fabricate the samples. Dynamic compaction was conducted at the strain rates of about 103 s−1. A mechanical drop hammer was used to fabricate the nanocomposite samples with relative density of up to 98%. The microstructural and mechanical behaviors of the samples, such as microhardness and stress–strain curves, were also investigated. The results showed improvement in microhardness and compressive strength of the material. The improvement is believed to be mainly due to the Orowan mechanism rather than the grain refinement described by the Hall–Petch effect. The results also revealed reduction in wear resistance as SiC reinforcing particles increased. The microstructural study of the eroded surfaces indicated that the abrasive and delamination were the dominant wear mechanisms.

The influence of electrolyte composition on the properties of Ni–Co alloy coatings reinforced by SiC nano-particles

Ni–Co alloy coatings reinforced by SiC nano-particles (Ni–Co/SiC nanocomposite coatings) were deposited in a modified Watts bath with different electrolyte compositions by sediment codeposition (SCD) technique. Chemical composition, phase structure, surface morphology, microhardness, and corrosion resistance of the coatings were studied. It was observed that the cobalt content in the coatings was increased by increasing the cobalt concentration in the bath. Moreover, particle incorporation was enhanced significantly from 2.0vol.% to 8.1vol.% as a function of the cobalt concentration. The studied surface morphologies were changed from pyramidal to spherical by increasing the cobalt content and the amount of SiC nano-particles. X-ray diffraction (XRD) patterns revealed that peak positions of the nanocomposite coatings were not changed appreciably whereas the phase structure, and peak intensities were significantly varied by adding cobalt in the electrolyte. The phase structure of the deposits was changed from fcc to fcc+hcp. The chemical composition of matrix and the amount of the incorporated particles had considerable influences on the microhardness and corrosion properties of the Ni–Co/SiC nanocomposite coatings. Ni–55Co/SiC nanocomposite coatings containing 55wt.% Co and 8.1vol.% SiC nano-particles exhibited the highest microhardness and the best corrosion resistance.

A comparative study on hot dynamic compaction and quasi-static hot pressing of Al7075/SiCnp nanocomposite

Quasi-static and hot dynamic compactions of Al7075/SiC nanocomposite powder are studied in this work. Mechanically milled micron-sized Al7075 with different amounts of SiC nano particles (SiCnp), 0vol%, 5vol%, and 10vol%, are used to fabricate the samples. Dynamic and quasi-static hot compaction is conducted at strain rates of 103s−1 and 8×10−3s−1, respectively. The hot compaction conducted at the process temperature of 698K produces nanocomposite samples with relative densities up to 98%. The micro-structural and mechanical behaviors of samples such as micro hardness and stress–strain curves under quasi-static and dynamic loadings are also investigated. The results show improvement in micro hardness of the material. The quasi-static and dynamic tests are carried out using Instron testing machine and split Hopkinson pressure bar (SHPB), respectively. The improvement is believed to be due to strengthening mechanisms such as Orowan and enhanced dislocation density induced by thermal mismatch phenomenon and not by grain refinement described by the Hall–Petch effect. The results from quasi-static compressive tests reveal higher strength for quasi-static hot pressed samples than those produced under dynamic compaction. However, the dynamic compressive tests using SHPB indicate similar compressive strength for both quasi-statically and dynamically compacted samples.

A comparative study of the effects of saccharin and β-SiC nano-particles on the properties of Ni and Ni–Co alloy coatings

The effects of saccharin and SiC nano-particles on the properties of Ni and Ni–Co based coatings electrodeposited in modified Watt's baths by sediment co-deposition (SCD) technique were studied. Surface morphologies of Ni and Ni–Co coatings were changed by using saccharin and SiC nano-particles. X-ray diffraction (XRD) results revealed that peak positions and the phase structure of the studied coatings did not change appreciably while the crystallite size and preferred orientation were significantly varied by using SiC nano-particles and particularly saccharin. Although the incorporation of SiC nano-particles had a slight influence on the microhardness of Ni based coatings, using saccharin enhanced their microhardness. However, there was no noticeable difference between the microhardness of Ni–45Co and Ni–45Co/saccharin coatings (containing 45wt.% Co) while the microhardness of Ni–55Co/SiC nanocomposite coatings (containing 55wt.% Co) was higher than Ni–45Co and Ni–45Co/saccharin coatings. The potentiodynamic polarization measurements indicated that the corrosion resistance of Ni/saccharin and Ni–45Co/saccharin coatings was better than pure Ni and Ni–45Co coatings. Additionally, the corrosion properties of Ni/SiC and Ni–55Co/SiC nanocomposite coatings were markedly higher than other coatings. Ni–55Co/SiC nanocomposite coatings showed the highest microhardness and corrosion resistance compared to all studied coatings. The unique properties of Ni–55Co/SiC nanocomposite coatings were linked to their alloy matrix and the amount of SiC nano-particles (8.1vol.%).

An Investigation on the Fatigue Fracture of P/M Al-SiC Nanocomposites

A tensile-compression fatigue response of Al matrix composites containing different amount of SiC nanoparticles (50 nm diameter) up to 6 vol. pct was studied. The nanocomposite powders were prepared by a powder metallurgy (P/M) route consisting of mechanical alloying, hot extrusion, and hot closed-die forging. The microstructure of the materials was evaluated by optical microscopy, scanning and transmission electron microscopies, and electron backscattered diffraction. A fine distribution of the nanoparticles in submicron and ultrafine grains was obtained. The low cycle fatigue behavior was examined in stress control mode under fully reversed tension-compression cycle at 1 Hz up to 1000 cycles. High cycle fatigue was conducted using a push-pull test up to 107 cycles with the minimum to maximum stress ratio of 0.1 at a frequency of 40 Hz. Cyclic hardening was observed at a low cycle fatigue regime with an enhanced hardening rate in the presence of SiC nanocomposite. The fatigue endurance limit at 107 cycles was also improved by nanoparticles. Fractographic studies revealed a mixture of ductile-brittle fracture modes with an increase in the ductile fracture mode at higher SiC fractions. The fatigue fracture mechanism was found to be local ductile deformation, microscopic void formation, and coalescence.