ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase c...ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase composition of ZrO_(2)ceramic coatings were inves-tigated by X-ray diffraction(XRD),energy-dispersive spectrometry(EDS)and scanning electron microscopy(SEM).The anti-permeation effect was measured by means of vacuum dehydrogenation experiment.It is found that the coating fabricated in phosphate electrolyte is more compact than that in silicate electrolyte.The coatings fabricated on the surface of ZrH_(1.8) are composed of M-ZrO_(2),T-ZrO_(2) and C-ZrO_(2).EDS analysis indicates that the coatings are mainly composed of O and Zr.Vacuum dehydrogenation experiment shows that the permeation reduction factor(PRF)of coating prepared in phosphate electrolyte is su-perior to that in the silicate electrolyte,and the PRF value reaches up to 11.2,which can enhance the resistance effect of hydrogen significantly.展开更多
BN–ZrO_(2)ceramics with different additives such as SiC,Al_(2)O_(3) and MgAl_(2)O_(4) were fabricated by hot pressing sintering process to study sintering properties and corrosion resistance by the rotary immersion m...BN–ZrO_(2)ceramics with different additives such as SiC,Al_(2)O_(3) and MgAl_(2)O_(4) were fabricated by hot pressing sintering process to study sintering properties and corrosion resistance by the rotary immersion molten steel test.The results showed that SiC,Al_(2)O_(3) and MgAl_(2)O_(4) can improve the sintering properties of BN–ZrO_(2)ceramics;especially,the introduction of SiC can significantly improve the hardness of the material;thus,the above compounds will help to improve the wear resistance of BN–ZrO_(2)ceramics.The exposed oxide layer is in contact with molten steel and forms liquid phase after BN oxidation and B_(2)O_(3) volatilization,additives can significantly affect the properties of liquid phase,and m-ZrO_(2)grains are sintered and grown by dissolution–precipitation mechanism by liquid phase.Consequently,Al_(2)O_(3) and MgAl_(2)O_(4) are more conducive to the formation of working layer with solid skeleton,which determines the corrosion resistance of BN–ZrO_(2)ceramics.展开更多
A type of polymer-coated Al2O3/ZrO2/TiC ceramic powder was prepared. The laser sintering mechanism of polymer-coated Al2O3/ZrO2/TiC powder was investigated by studying the dynamic laser sintering process. It is found ...A type of polymer-coated Al2O3/ZrO2/TiC ceramic powder was prepared. The laser sintering mechanism of polymer-coated Al2O3/ZrO2/TiC powder was investigated by studying the dynamic laser sintering process. It is found that the mechanism is viscous flow when the sintering temperature is between 80 ℃ and 120 ℃, and it is melting/solidification when the temperature is above 120 ℃. The process parameters of selective laser sintering were optimized by using ortho-design method. The results show that the optimal parameters include laser power of 14 W, scanning velocity of 1 400 mm/s, preheating temperature of 50 ℃ and powder depth of 0.15 mm. A two-step post-treatment process is adopted to improve the mechanical properties of laser sintered part, which includes polymer debinding and high temperature sintering. After vacuum sintering for 2 h at 1 650 ℃, the bending strength and fracture toughness of Al2O3/ZrO2/TiC ceramic part reach 358 MPa and 6.9 MPa·m1/2, respectively.展开更多
基金financially supported by the National Natural Science Foundation (Nos. 51164023 and 513640236)the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (No. NJYT-13B10)the Program for New Century Excellent Talents in University (No. NCET-13-0847)。
文摘ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase composition of ZrO_(2)ceramic coatings were inves-tigated by X-ray diffraction(XRD),energy-dispersive spectrometry(EDS)and scanning electron microscopy(SEM).The anti-permeation effect was measured by means of vacuum dehydrogenation experiment.It is found that the coating fabricated in phosphate electrolyte is more compact than that in silicate electrolyte.The coatings fabricated on the surface of ZrH_(1.8) are composed of M-ZrO_(2),T-ZrO_(2) and C-ZrO_(2).EDS analysis indicates that the coatings are mainly composed of O and Zr.Vacuum dehydrogenation experiment shows that the permeation reduction factor(PRF)of coating prepared in phosphate electrolyte is su-perior to that in the silicate electrolyte,and the PRF value reaches up to 11.2,which can enhance the resistance effect of hydrogen significantly.
基金The authors gratefully acknowledge the support of National Natural Science Foundation of China(51932008 and 51772277)Central China Thousand Talents Project(204200510011).
文摘BN–ZrO_(2)ceramics with different additives such as SiC,Al_(2)O_(3) and MgAl_(2)O_(4) were fabricated by hot pressing sintering process to study sintering properties and corrosion resistance by the rotary immersion molten steel test.The results showed that SiC,Al_(2)O_(3) and MgAl_(2)O_(4) can improve the sintering properties of BN–ZrO_(2)ceramics;especially,the introduction of SiC can significantly improve the hardness of the material;thus,the above compounds will help to improve the wear resistance of BN–ZrO_(2)ceramics.The exposed oxide layer is in contact with molten steel and forms liquid phase after BN oxidation and B_(2)O_(3) volatilization,additives can significantly affect the properties of liquid phase,and m-ZrO_(2)grains are sintered and grown by dissolution–precipitation mechanism by liquid phase.Consequently,Al_(2)O_(3) and MgAl_(2)O_(4) are more conducive to the formation of working layer with solid skeleton,which determines the corrosion resistance of BN–ZrO_(2)ceramics.
基金Project(03022) supported by the Key Science Research Program of Education Ministry of China
文摘A type of polymer-coated Al2O3/ZrO2/TiC ceramic powder was prepared. The laser sintering mechanism of polymer-coated Al2O3/ZrO2/TiC powder was investigated by studying the dynamic laser sintering process. It is found that the mechanism is viscous flow when the sintering temperature is between 80 ℃ and 120 ℃, and it is melting/solidification when the temperature is above 120 ℃. The process parameters of selective laser sintering were optimized by using ortho-design method. The results show that the optimal parameters include laser power of 14 W, scanning velocity of 1 400 mm/s, preheating temperature of 50 ℃ and powder depth of 0.15 mm. A two-step post-treatment process is adopted to improve the mechanical properties of laser sintered part, which includes polymer debinding and high temperature sintering. After vacuum sintering for 2 h at 1 650 ℃, the bending strength and fracture toughness of Al2O3/ZrO2/TiC ceramic part reach 358 MPa and 6.9 MPa·m1/2, respectively.
