Ni-Co-Fe2O3 composite coatings were electrodeposited using cetyltrimethylammonium bromide(CTAB)-modified Watt's nickel bath with Fe2O3 particles dispersed in it.The effects of the plating parameters on the chemica...Ni-Co-Fe2O3 composite coatings were electrodeposited using cetyltrimethylammonium bromide(CTAB)-modified Watt's nickel bath with Fe2O3 particles dispersed in it.The effects of the plating parameters on the chemical composition,structural and morphological characteristics of the electrodeposited Ni-Co-Fe2O3 composite coatings were investigated by energy dispersive X-ray(EDS) spectroscopy,X-ray diffractometry(XRD) and scanning electron microscopy(SEM).The results reveal that Fe2O3 particles can be codeposited in the Ni-Co matrix.The codeposition of Fe2O3 particles with Ni-Co is favoured at high Fe2O3 particle concentration and medium stirring,and the deposition of Co is favoured at high concentration of CTAB.Moreover,the study of the textural perfection of the deposits reveals that the presence of particles leads to the worsening of the quality of the observed <220> preferred orientation.Composites with high concentration of embedded particles exhibit a preferred crystal orientation of <111>.The more the embedded Fe2O3 particles in the metallic matrix,the smaller the sizes of the crystallite for the composite deposits.展开更多
The effects of hot extrusion and addition of Al_(2)O_(3p) on both microstructure and tribological behavior of 7075 composites were investigated via optical microscopy(OM),scanning electron microscopy(SEM),energy dispe...The effects of hot extrusion and addition of Al_(2)O_(3p) on both microstructure and tribological behavior of 7075 composites were investigated via optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive spectrometry(EDS),and transmission electron microscopy(TEM).The experimental consequences reveal that the optimal addition of Al_(2)O_(3p) was 2 wt%.After hot extrusion,the Mg(Zn,Cu,Al)2 phases partially dissolve into the matrix and generate many uniformly distributed aging precipitation particles,the Al_(7)Cu_(2)Fe phases are squeezed and broken,and the Al_(2)O_(3p) become uniform distribution.The microhardness of as-extruded 2 wt%Al_(2)O_(3p)/7075 composites reaches HV 170.34,increased by 41.5%than as-cast composites.The wear rate of as-extruded 2 wt%Al_(2)O_(3p)/7075 composites is further lower than that of as-cast composites under the same condition.SEM-EDS analyses reveal that the reinforced wear resistance of composites can put down to the protective effect of the Al_(2)O_(3p) reinforced transition layer.After hot extrusion,the transition layer becomes stable,which determines the reinforced wear resistance of the as-extruded composites.展开更多
BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions （10%-60%） of hexagonal BN particulates （BNp） were prepared by hot-press sintering technique. Phase components, microstructure, mechan...BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions （10%-60%） of hexagonal BN particulates （BNp） were prepared by hot-press sintering technique. Phase components, microstructure, mechanical properties and plasma erosion resistance were also investigated. With the increase of h-BNp content, relative density and Vickers＇ hardness of the composite ceramics decrease, while the flexural strength, elastic modulus and fracture toughness increase and then decrease. The plasma erosion resistance linearly deteriorated with the increase of BNp content which is mainly determined by the density, crystal structure and atomic number of the elements.展开更多
基金Project(2005CB623703) supported by the National Key Basic Research Program of ChinaProject(50474051) supported by the National Natural Science Foundation of China+2 种基金Project(CX2009B032) supported by Innovation Foundation for Postgraduate of Hunan Province of China Project(ZKJ2009024) supported by the Precious Apparatus Open Share Foundation of Central South University, ChinaProject(2009ybfz02) supported by Excellent Doctor Support Fund of Central South University,China
文摘Ni-Co-Fe2O3 composite coatings were electrodeposited using cetyltrimethylammonium bromide(CTAB)-modified Watt's nickel bath with Fe2O3 particles dispersed in it.The effects of the plating parameters on the chemical composition,structural and morphological characteristics of the electrodeposited Ni-Co-Fe2O3 composite coatings were investigated by energy dispersive X-ray(EDS) spectroscopy,X-ray diffractometry(XRD) and scanning electron microscopy(SEM).The results reveal that Fe2O3 particles can be codeposited in the Ni-Co matrix.The codeposition of Fe2O3 particles with Ni-Co is favoured at high Fe2O3 particle concentration and medium stirring,and the deposition of Co is favoured at high concentration of CTAB.Moreover,the study of the textural perfection of the deposits reveals that the presence of particles leads to the worsening of the quality of the observed <220> preferred orientation.Composites with high concentration of embedded particles exhibit a preferred crystal orientation of <111>.The more the embedded Fe2O3 particles in the metallic matrix,the smaller the sizes of the crystallite for the composite deposits.
基金Project(51965040)supported by the National Natural Science Foundation of ChinaProject(20181BAB206026)supported by the National Science Foundation of Jiangxi Province,China。
文摘The effects of hot extrusion and addition of Al_(2)O_(3p) on both microstructure and tribological behavior of 7075 composites were investigated via optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive spectrometry(EDS),and transmission electron microscopy(TEM).The experimental consequences reveal that the optimal addition of Al_(2)O_(3p) was 2 wt%.After hot extrusion,the Mg(Zn,Cu,Al)2 phases partially dissolve into the matrix and generate many uniformly distributed aging precipitation particles,the Al_(7)Cu_(2)Fe phases are squeezed and broken,and the Al_(2)O_(3p) become uniform distribution.The microhardness of as-extruded 2 wt%Al_(2)O_(3p)/7075 composites reaches HV 170.34,increased by 41.5%than as-cast composites.The wear rate of as-extruded 2 wt%Al_(2)O_(3p)/7075 composites is further lower than that of as-cast composites under the same condition.SEM-EDS analyses reveal that the reinforced wear resistance of composites can put down to the protective effect of the Al_(2)O_(3p) reinforced transition layer.After hot extrusion,the transition layer becomes stable,which determines the reinforced wear resistance of the as-extruded composites.
基金Project(HIT.NSRIF.2010112)supported by the Fundamental Research Fund for the Central Universities,ChinaProjects(50902030,51021002)supported by the National Natural Science Foundation of China
文摘BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions （10%-60%） of hexagonal BN particulates （BNp） were prepared by hot-press sintering technique. Phase components, microstructure, mechanical properties and plasma erosion resistance were also investigated. With the increase of h-BNp content, relative density and Vickers＇ hardness of the composite ceramics decrease, while the flexural strength, elastic modulus and fracture toughness increase and then decrease. The plasma erosion resistance linearly deteriorated with the increase of BNp content which is mainly determined by the density, crystal structure and atomic number of the elements.
