Effects of VC/Cr3C2 on the microstructure and mechanical properties of Ti（C,N）-based cermets were studied. The microstructure was investigated by means of optical microscopy, X-ray diffractometry as well as scanning...Effects of VC/Cr3C2 on the microstructure and mechanical properties of Ti（C,N）-based cermets were studied. The microstructure was investigated by means of optical microscopy, X-ray diffractometry as well as scanning electron microscopy in combination with energy dispersive spectrometry. Mechanical properties, such as transverse rupture strength, hardness and fracture toughness, were measured. The results show that there are black core-grey rim structure and white core-grey rim structure in the microstructure. The grains become fine due to the VC/Cr3C2, and the grains of cermet added with 0.75VC/0.25Cr3C2 are refined most remarkably. The black core becomes finer with the increase of VC addition and rim phase becomes thicker with the decrease of Cr3C2 addition. The porosity increases with the increase of VC addition in VC/Cr3C2. Compared with the cermet free of VC/Cr3C2, the transverse rupture strength and hardness of cermets with VC/Cr3C2 are both improved, and the maximum values are both found for the cermet with 0.25VC/0.75Cr3C2. The fracture toughness can be effectively promoted by adding VC/Cr3C2 with an appropriate ratio of VC to Cr3C2, and the maximum value is found for the cermet with 0.5VC/0.5Cr3C2.展开更多
A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rate...A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 （volume fraction） are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer （about 50 μm） is thicker than that （about 30 μm） formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe（II） in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.展开更多
NiFe2O4-10NiO-based cermet inert anodes for aluminium electrolysis were prepared and their properties were investigated in a lab-scale electrolysis cell. The results show that the inert anodes exhibit good performance...NiFe2O4-10NiO-based cermet inert anodes for aluminium electrolysis were prepared and their properties were investigated in a lab-scale electrolysis cell. The results show that the inert anodes exhibit good performance during electrolysis in molten salt cryolite at 960 °C, but according to the analyses of phase compositions and microstructures through XRD, SEM/EDX and metallographic analysis, the metal in the anodes is preferentially corroded and many pores are produced on the anode surface after electrolysis. The preferential dissolution of Fe in the NiFe2O4 phase may lead to the non-uniform corrosion of NiFe2O4 grains. Moreover, a dense protective layer of NiFe2O4-NiAl2O4-FeAl2O4 is formed on the anode surface, which originates from the reaction of Al2O3 dissolved in the electrolyte with NiO or FeO, the annexation of NiFe2O4-NiAl2O4-FeAl2O4 to NiO and volume expansion. Thus, the dense NiFe2O4-NiAl2O4-FeAl2O4 layer inhibits the metal loss and ceramic-phase corrosion on the surface of the cermet inert anodes.展开更多
基金Project (090414185) supported by the Natural Science Foundation of Anhui Province, China
文摘Effects of VC/Cr3C2 on the microstructure and mechanical properties of Ti（C,N）-based cermets were studied. The microstructure was investigated by means of optical microscopy, X-ray diffractometry as well as scanning electron microscopy in combination with energy dispersive spectrometry. Mechanical properties, such as transverse rupture strength, hardness and fracture toughness, were measured. The results show that there are black core-grey rim structure and white core-grey rim structure in the microstructure. The grains become fine due to the VC/Cr3C2, and the grains of cermet added with 0.75VC/0.25Cr3C2 are refined most remarkably. The black core becomes finer with the increase of VC addition and rim phase becomes thicker with the decrease of Cr3C2 addition. The porosity increases with the increase of VC addition in VC/Cr3C2. Compared with the cermet free of VC/Cr3C2, the transverse rupture strength and hardness of cermets with VC/Cr3C2 are both improved, and the maximum values are both found for the cermet with 0.25VC/0.75Cr3C2. The fracture toughness can be effectively promoted by adding VC/Cr3C2 with an appropriate ratio of VC to Cr3C2, and the maximum value is found for the cermet with 0.5VC/0.5Cr3C2.
基金Project(51474238)supported by the National Natural Science Foundation of China
文摘A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 （volume fraction） are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer （about 50 μm） is thicker than that （about 30 μm） formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe（II） in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.
基金Project (2012FJ6123) supported by the Project of Science and Technology of Hunan Province,ChinaProject supported by Post-Doctoral Foundation of Central South University,China+1 种基金Project (CL12100) supported the Undergraduate Innovative Training of Central South University,ChinaProject (2282013bkso13) supported by Free Exploration Plan of Central South University,China
文摘NiFe2O4-10NiO-based cermet inert anodes for aluminium electrolysis were prepared and their properties were investigated in a lab-scale electrolysis cell. The results show that the inert anodes exhibit good performance during electrolysis in molten salt cryolite at 960 °C, but according to the analyses of phase compositions and microstructures through XRD, SEM/EDX and metallographic analysis, the metal in the anodes is preferentially corroded and many pores are produced on the anode surface after electrolysis. The preferential dissolution of Fe in the NiFe2O4 phase may lead to the non-uniform corrosion of NiFe2O4 grains. Moreover, a dense protective layer of NiFe2O4-NiAl2O4-FeAl2O4 is formed on the anode surface, which originates from the reaction of Al2O3 dissolved in the electrolyte with NiO or FeO, the annexation of NiFe2O4-NiAl2O4-FeAl2O4 to NiO and volume expansion. Thus, the dense NiFe2O4-NiAl2O4-FeAl2O4 layer inhibits the metal loss and ceramic-phase corrosion on the surface of the cermet inert anodes.
