A modified superscalar parallelization based phase-locked loop combined with the maximum-likeliho... more A modified superscalar parallelization based phase-locked loop combined with the maximum-likelihood algorithm is proposed. Its high tolerance to laser linewidth is demonstrated both numerically and experimentally.
In this paper, the microstructures of Cr–Mo–Cu alloy cast irons with and without nano-additives w... more In this paper, the microstructures of Cr–Mo–Cu alloy cast irons with and without nano-additives were characterized by scanning electron microscope (SEM) and energy diffraction spectrum analyser (EDS). The dry sliding wear tests were carried out using a pin-on-disk wear tester against GCr15 steel balls under fixed normal load and rotating velocity. The study aimed to illustrate the effect of graphite
ABSTRACT NiCrAlY coatings without and with 0.2 wt.% nano ceria were prepared by high velocity oxy... more ABSTRACT NiCrAlY coatings without and with 0.2 wt.% nano ceria were prepared by high velocity oxygen fuel spraying. The microstructure, mechanical properties, and thermal shock resistance of as-sprayed coatings were investigated. The results showed that in the as-sprayed coatings, the number of un-melted particles was reduced drastically, the microstructure was refined and compact due to the refinement of sprayable powders. Both the hardness and adhesive strength of the NiCrAlY increased due to the refinement of microstructure and the decrease of the defects, such as pores and oxides, after adding nano ceria. The thermal cycle life of NiCrAlY coatings was improved by 15% after adding 0.2 wt.% nano ceria, which is attributed to the low content of spinel NiCr2O4 and high content of Cr2O3 in the thermal cycling, the refined and compact microstructure, and increased interfacial boundary.
ABSTRACT In this paper, the microstructure of WC-Co alloys with and without nano-additives was ch... more ABSTRACT In this paper, the microstructure of WC-Co alloys with and without nano-additives was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The hardness and fracture toughness was tested by using a Vickers hardness tester and a universal testing machine. The cutting test was carried out at different feed velocities (250 r/min and 320 r/min), and the contact pairs are cutting tools and 45# steel bars. Results showed that the hardness and fracture toughness of WC-Co cemented carbides with nano-additives are higher than that of WC-Co cemented carbides without nano-additives, and they are increased 10.21% and 19.69%, respectively. The flank worn width and crater width of cutting tools decrease greatly with the addition of nano-additives. For the nano-modified specimen with WC grain size of 7 μm, both the flank worn width and crater width are the minimum after the cutting process. And there are little built-up layers and some pile-up regions on the flank face leading to high cutting performance for the nano-modified cemented carbides. There are some melted regions on the flank face of cutting tools without nano-additives, and the WC grains on the cross section of alloys without nano-additives show severe fragmentation. The wear type of WC-Co is flank wear, and the wear mechanism is abrasive, adhesion and oxidation wear.
Journal of Materials Engineering and Performance, 2013
ABSTRACT Nine types of trace nano-CeO2-doped WC-11Co cemented carbides designed by orthogonal met... more ABSTRACT Nine types of trace nano-CeO2-doped WC-11Co cemented carbides designed by orthogonal method were prepared. The variance analysis results show that the relative density increases with increasing sintering temperature in the range of 1400-1450 °C; the hardness is highly dependent on grain size of WC which is closely related to the particle size of the initial WC powder and grain refinement produced by nano-CeO2; the bending strength of WC-11Co cemented carbide with less than 0.15 wt.% of nano-CeO2 is effectively improved because of its effect on the decreasing of porosity and inhibiting the grain growth of WC and martensitic phase transformation of Co; the fracture toughness rises at the beginning then drops later if the particle size of initial WC powder is in the range of 3-11 μm.
A modified superscalar parallelization based phase-locked loop combined with the maximum-likeliho... more A modified superscalar parallelization based phase-locked loop combined with the maximum-likelihood algorithm is proposed. Its high tolerance to laser linewidth is demonstrated both numerically and experimentally.
In this paper, the microstructures of Cr–Mo–Cu alloy cast irons with and without nano-additives w... more In this paper, the microstructures of Cr–Mo–Cu alloy cast irons with and without nano-additives were characterized by scanning electron microscope (SEM) and energy diffraction spectrum analyser (EDS). The dry sliding wear tests were carried out using a pin-on-disk wear tester against GCr15 steel balls under fixed normal load and rotating velocity. The study aimed to illustrate the effect of graphite
ABSTRACT NiCrAlY coatings without and with 0.2 wt.% nano ceria were prepared by high velocity oxy... more ABSTRACT NiCrAlY coatings without and with 0.2 wt.% nano ceria were prepared by high velocity oxygen fuel spraying. The microstructure, mechanical properties, and thermal shock resistance of as-sprayed coatings were investigated. The results showed that in the as-sprayed coatings, the number of un-melted particles was reduced drastically, the microstructure was refined and compact due to the refinement of sprayable powders. Both the hardness and adhesive strength of the NiCrAlY increased due to the refinement of microstructure and the decrease of the defects, such as pores and oxides, after adding nano ceria. The thermal cycle life of NiCrAlY coatings was improved by 15% after adding 0.2 wt.% nano ceria, which is attributed to the low content of spinel NiCr2O4 and high content of Cr2O3 in the thermal cycling, the refined and compact microstructure, and increased interfacial boundary.
ABSTRACT In this paper, the microstructure of WC-Co alloys with and without nano-additives was ch... more ABSTRACT In this paper, the microstructure of WC-Co alloys with and without nano-additives was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The hardness and fracture toughness was tested by using a Vickers hardness tester and a universal testing machine. The cutting test was carried out at different feed velocities (250 r/min and 320 r/min), and the contact pairs are cutting tools and 45# steel bars. Results showed that the hardness and fracture toughness of WC-Co cemented carbides with nano-additives are higher than that of WC-Co cemented carbides without nano-additives, and they are increased 10.21% and 19.69%, respectively. The flank worn width and crater width of cutting tools decrease greatly with the addition of nano-additives. For the nano-modified specimen with WC grain size of 7 μm, both the flank worn width and crater width are the minimum after the cutting process. And there are little built-up layers and some pile-up regions on the flank face leading to high cutting performance for the nano-modified cemented carbides. There are some melted regions on the flank face of cutting tools without nano-additives, and the WC grains on the cross section of alloys without nano-additives show severe fragmentation. The wear type of WC-Co is flank wear, and the wear mechanism is abrasive, adhesion and oxidation wear.
Journal of Materials Engineering and Performance, 2013
ABSTRACT Nine types of trace nano-CeO2-doped WC-11Co cemented carbides designed by orthogonal met... more ABSTRACT Nine types of trace nano-CeO2-doped WC-11Co cemented carbides designed by orthogonal method were prepared. The variance analysis results show that the relative density increases with increasing sintering temperature in the range of 1400-1450 °C; the hardness is highly dependent on grain size of WC which is closely related to the particle size of the initial WC powder and grain refinement produced by nano-CeO2; the bending strength of WC-11Co cemented carbide with less than 0.15 wt.% of nano-CeO2 is effectively improved because of its effect on the decreasing of porosity and inhibiting the grain growth of WC and martensitic phase transformation of Co; the fracture toughness rises at the beginning then drops later if the particle size of initial WC powder is in the range of 3-11 μm.
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