“…Relatively lower strength and large wear rate of the conventionally sintered samples can be attributed to inhomogeneous temperature distribution in the tubolar furnace. On the other Hand, microwave sintered samples have higher densification and lower porosity levels and yield higher strength and ductility [50]. Figure 8 Wear rate data from wear tests for samples sintered by means of conventional sintering and microwave sintering.…”
In the present study, the effects of microwave sintering (MWS) on microstructural, tribological and corrosion properties of Cu 0.7 Ni 0.3 -5 wt-% Al 2 O 3 nanocomposites were evaluated. The Cu and Ni powders along with Al 2 O 3 nanopowder were mixed in a high-energy ball mill. The XRD patterns indicating formation of Cu 0.7 Ni 0.3 solid solution alloy during mechanical alloying process. The mechanically alloyed powders were compacted by coldpress, and sintered samples at 200 and 300°C for 30 and 60 min by means of conventional sintering and MWS. Tribological properties of sintered samples were evaluated by ball-on-disk wear test. For MWS, results indicate that increasing the MWS temperature decreased the wear rate about 30%. Corrosion behaviour of nanocomposites were studied by cyclic potentiodynamic polarisation in 1 M NaOH solution and was found that corrosion current density of microwave sintered sample was decreased almost 35 times of that for conventional sintered sample.
“…Relatively lower strength and large wear rate of the conventionally sintered samples can be attributed to inhomogeneous temperature distribution in the tubolar furnace. On the other Hand, microwave sintered samples have higher densification and lower porosity levels and yield higher strength and ductility [50]. Figure 8 Wear rate data from wear tests for samples sintered by means of conventional sintering and microwave sintering.…”
In the present study, the effects of microwave sintering (MWS) on microstructural, tribological and corrosion properties of Cu 0.7 Ni 0.3 -5 wt-% Al 2 O 3 nanocomposites were evaluated. The Cu and Ni powders along with Al 2 O 3 nanopowder were mixed in a high-energy ball mill. The XRD patterns indicating formation of Cu 0.7 Ni 0.3 solid solution alloy during mechanical alloying process. The mechanically alloyed powders were compacted by coldpress, and sintered samples at 200 and 300°C for 30 and 60 min by means of conventional sintering and MWS. Tribological properties of sintered samples were evaluated by ball-on-disk wear test. For MWS, results indicate that increasing the MWS temperature decreased the wear rate about 30%. Corrosion behaviour of nanocomposites were studied by cyclic potentiodynamic polarisation in 1 M NaOH solution and was found that corrosion current density of microwave sintered sample was decreased almost 35 times of that for conventional sintered sample.
“…The structural evolution and morphological changes observed in the present work after the high energy ball milling treatment is consistent with the results obtained in similar studies. In research by Sharma et al [46], commercially available CoNiCrAlY powder was subjected to ball milling. They have obtained nanocrystalline CoNiCrAlY powders with the particle size of 5-25 μm, after 48 h ball milling.…”
Section: Preparation Of Nanocomposite Nicocraly-ceo 2 Powdersmentioning
This paper investigates NiCoCrAlY-CeO 2 nanocomposite powders prepared by mechanical milling process. At first, micron-sized ceria powder was pre-milled to obtain nano-sized powders and then 1 wt% CeO 2 was mixed with the conventional NiCoCrAlY powder and milled under three sets of parameters. The conventional and milled powders were deposited on low carbon steel substrates by HVOF thermal spray technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), fieldemission scanning electron microscopy (FESEM) and image analyzing method were used to characterize the prepared powders and coatings. Microstructural characterization showed that the milled powders underwent morphological and phase transitions. Through the microstructural and compositional analyses, it was found that a homogeneous distribution of CeO 2 nano-dispersoids in the NiCoCrAlY matrix was obtained. The resulting coatings showed that by using optimized milling parameters, required particle size and suitable morphology for thermal spray can be achieved.
“…It appeared that the method of the electrical consolidation by the direct passing of the current was very effective in case of conductive nanopowders sintering. In the case of non-conducting nanopowders, rather a microwave sintering is applied [5], where the heating process of dielectric losses under the influence of high-frequency electric field takes place. In both cases, usually high heating rates are used.…”
Nanostructured ceramic materials and compositions based on them find an increasing application in all branches of science and technology. At the same time, the performance properties of new ceramic nanomaterials (strength, adhesion, optical and others) are significantly different from properties of traditional ceramics, which were used before. The qualitative characteristics of nanoceramics are largely determined by the initial structure and methods of nanopowder synthesis, as well as by the characteristics of conditions and methods for their consolidation. This work is devoted to the synthesis of nanopowders and effective method of its sintering for the production of nanoceramic materials which have special mechanical properties, e.g. components with increased modulus of elasticity ("ceramic steel"), etc. It makes it possible to effectively use them in aerospace industry.
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