With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences too...With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences took on a plurality of accelerator projects.Nevertheless,the stability of the coupler,a crucial system within the cavities of accelerators,has encountered certain difficulties.The alumina ceramics,which constitute the core component of the coupler,are increasingly prone to breakage and solder joint failures due to their inferior environmental adaptability,inadequate mechanical properties,and high gas emissions.Conversely,with the advancements in medical technology and materials science,zirconia ceramics have emerged as a prospective remedy for these problems.This type of ceramic is highly esteemed for its outstanding environmental adaptability,remarkable mechanical properties,and excellent high-temperature resistance,exhibiting extraordinary value in dental applications.This study investigates the use of zirconia ceramics in a 162.5 MHz 3-1/8"standard ceramic window,combining experimental data with finite element RF simulations and multi-physics analysis.A new coupler featuring a zirconia ceramic window was tested on a Quarter-Wave Resonator,demonstrating excellent alignment between electromagnetic simulations and measurement results.This reveals the substantial application potential and practical worth of the zirconia ceramic material in the context of accelerators.展开更多
Zirconia(ZrO_(2))ceramic material has been widely applied to various fields due to its unique properties of high strength,high hardness,and excessive temperature resistance.However,the high-quality micro-hole machinin...Zirconia(ZrO_(2))ceramic material has been widely applied to various fields due to its unique properties of high strength,high hardness,and excessive temperature resistance.However,the high-quality micro-hole machining of zirconia ceramic material remains a significant challenge at present.In this study,experiments on peck drilling of 0.2 mm and 0.5 mm micro-holes in zirconia ceramics using diamond-coated drills are conducted.The characteristics of the force signal during the drilling process,the influence of drilling parameters on the drlling force and the chipping size at the hole exit,and features of the tool wear stages of the diamond coated drill are analyzed.Experimental results suggest that when machining micro-holes in zirconia ceramics,there is a positive correlation between the axial force and the size of the chipping at the exit.The axial force increases with the increase of the feed rate and the step distance,and it shows a trend of first increasing and next decreasing with the increase of the spindle speed.The wear of the drll bit has a significant impact on the quality of the hole exit.It is found that with the continuous drilling of seven holes,the axial force increases by 144.2%,and the size of edge chipping at the exit increases from about 20μm to more than 130μm.This study can provide some valuable references for improving the micro-hole processing quality of material.展开更多
Ceria-stabilized tetragonal zirconia(Ce-TZP)has become an interesting alternative for the widely used yttria-stabilized zirconia(Y-TZP),whereas efforts are needed to control its microstructure in order to im-prove the...Ceria-stabilized tetragonal zirconia(Ce-TZP)has become an interesting alternative for the widely used yttria-stabilized zirconia(Y-TZP),whereas efforts are needed to control its microstructure in order to im-prove the strength of Ce-TZP ceramics.In this work,CaO was used to co-dope Ce-TZP ceramics.More specifically,0.2-2.0 mol%Ca(NO_(3))_(3)·4H_(2)O precursor-based CaO was used to dope 10 mol%ceria-stabilized zirconia.Sintering was performed at 1300,1350,or 1400℃,which is lower than the temperatures commonly applied for zirconia ceramics.The microstructure and mechanical properties were investigated and correlated,revealing that 0.2 mol%CaO-doped CeO_(2)-stabilised zirconia sintered at 1350℃ exhibited a fully dense fine-grained tetragonal ZrO_(2) microstructure with high toughness(10.4 MPa m1/2)and biax-ial bending strength(1210±43 MPa),and a narrow strength distribution(weibull modulus of 32.5).1.5 and 2.0 mol% CaO-doping resulted in excellent biaxial bending strength but wider strength distribution and lower fracture resistance.The homogeneously distributed Ca(NO_(3))_(3)·4H_(2)O precursor prevented cubic zirconia-phase formation for CaO-doping up to 2.0 mol%.CaO-doped(≥0.2 mol%)10Ce-TZP sintered at 1350℃ also highly resisted hydrothermal degradation.Furthermore,CaO-doping enabled to make Ce-TZP ceramics as translucent as different commercially available 3Y-TZP ceramics,opening possibilities to use Ce-TZP for dental restorations.展开更多
An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microst...An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microstructure evolution and properties of magnesia–spinel refractories were characterized by the high-temperature elastic modulus,thermal shock damage resistance parameters,retainment of elastic modulus after thermal shock,and scanning electron microscopy.The results indicated that the incorporation of calcia-stabilized zirconia improved the thermomechanical properties and thermal shock behavior of magnesia–spinel specimens.The hot modulus of rupture of magnesia–spinel specimens increased by 2.5-fold due to the incorporation of calcia-stabilized zirconia micro-powder.The presence of a martensitic phase transformation in partially unstable ZrO2 and thermal mismatches among various phases contributed to a controlled formation of microcracks.And the pinning effect caused by the calcia-stabilized zirconia particles surrounding the grain boundaries played a crucial role in preventing the propagation of microcracks.This phenomenon significantly bolstered the thermal shock stability of magnesia–spinel refractories,consequently prolonging their service life.展开更多
Aim To evaluate the interactive effects of different self- adhesive resin cements and tribochemical treatment on bond strength to zirconia. Methodology The following self-adhesive resin cements for bonding two zirconi...Aim To evaluate the interactive effects of different self- adhesive resin cements and tribochemical treatment on bond strength to zirconia. Methodology The following self-adhesive resin cements for bonding two zirconia blocks were evaluated： Maxcem （MA）, Smartcem （SM）, Rely X Unicem Aplicap （UN）, Breeze （BR）, Biscem （BI）, Set （SE）, and Clearfil SA luting （CL）. The specimens were grouped according to conditioning as follows： Group 1, polishing with 600 grit polishing paper; Group 2, silica coating with 110 μm Al2O3 particles which modified with silica; and, Group 3, tribochemical treatment - silica coating ＋ silanization. Specimens were stored in distilled water at 37℃ for 24 hours before testing shear bond strength. Results Silica coating and tribochemical treatment significantly increased the bond strength of the MA, UN, BR, B1, SE and CL to zirconia compared to #600 polishing. For both #600 polished and silica coating treatments, MDP- containing self-adhesive resin cement CL had the highest bond strengths to zirconia. Conclusion Applying silica coating and tribochemical treatment improved the bond strength of self-adhesive resin cement to zirconia, especially for CL.展开更多
文摘With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences took on a plurality of accelerator projects.Nevertheless,the stability of the coupler,a crucial system within the cavities of accelerators,has encountered certain difficulties.The alumina ceramics,which constitute the core component of the coupler,are increasingly prone to breakage and solder joint failures due to their inferior environmental adaptability,inadequate mechanical properties,and high gas emissions.Conversely,with the advancements in medical technology and materials science,zirconia ceramics have emerged as a prospective remedy for these problems.This type of ceramic is highly esteemed for its outstanding environmental adaptability,remarkable mechanical properties,and excellent high-temperature resistance,exhibiting extraordinary value in dental applications.This study investigates the use of zirconia ceramics in a 162.5 MHz 3-1/8"standard ceramic window,combining experimental data with finite element RF simulations and multi-physics analysis.A new coupler featuring a zirconia ceramic window was tested on a Quarter-Wave Resonator,demonstrating excellent alignment between electromagnetic simulations and measurement results.This reveals the substantial application potential and practical worth of the zirconia ceramic material in the context of accelerators.
基金supported by the National Natural Science Foundation of China(Nos.51805242,52475463).
文摘Zirconia(ZrO_(2))ceramic material has been widely applied to various fields due to its unique properties of high strength,high hardness,and excessive temperature resistance.However,the high-quality micro-hole machining of zirconia ceramic material remains a significant challenge at present.In this study,experiments on peck drilling of 0.2 mm and 0.5 mm micro-holes in zirconia ceramics using diamond-coated drills are conducted.The characteristics of the force signal during the drilling process,the influence of drilling parameters on the drlling force and the chipping size at the hole exit,and features of the tool wear stages of the diamond coated drill are analyzed.Experimental results suggest that when machining micro-holes in zirconia ceramics,there is a positive correlation between the axial force and the size of the chipping at the exit.The axial force increases with the increase of the feed rate and the step distance,and it shows a trend of first increasing and next decreasing with the increase of the spindle speed.The wear of the drll bit has a significant impact on the quality of the hole exit.It is found that with the continuous drilling of seven holes,the axial force increases by 144.2%,and the size of edge chipping at the exit increases from about 20μm to more than 130μm.This study can provide some valuable references for improving the micro-hole processing quality of material.
基金the China Scholarship Council(CSC No.201806460096)for financial supportthe Scientific Research-Flanders(FWO-Vlaanderen)for her post-doctoral fellowships(grant Nos.12S8418N and 12S8421N)supported by the Research Fund of KU Leuven project No.C2-17-00402 and the Fund for Scientific Research-Flanders(FWO-Vlaanderen)(grant Nos.G.0431.10N and G.0959.20N).
文摘Ceria-stabilized tetragonal zirconia(Ce-TZP)has become an interesting alternative for the widely used yttria-stabilized zirconia(Y-TZP),whereas efforts are needed to control its microstructure in order to im-prove the strength of Ce-TZP ceramics.In this work,CaO was used to co-dope Ce-TZP ceramics.More specifically,0.2-2.0 mol%Ca(NO_(3))_(3)·4H_(2)O precursor-based CaO was used to dope 10 mol%ceria-stabilized zirconia.Sintering was performed at 1300,1350,or 1400℃,which is lower than the temperatures commonly applied for zirconia ceramics.The microstructure and mechanical properties were investigated and correlated,revealing that 0.2 mol%CaO-doped CeO_(2)-stabilised zirconia sintered at 1350℃ exhibited a fully dense fine-grained tetragonal ZrO_(2) microstructure with high toughness(10.4 MPa m1/2)and biax-ial bending strength(1210±43 MPa),and a narrow strength distribution(weibull modulus of 32.5).1.5 and 2.0 mol% CaO-doping resulted in excellent biaxial bending strength but wider strength distribution and lower fracture resistance.The homogeneously distributed Ca(NO_(3))_(3)·4H_(2)O precursor prevented cubic zirconia-phase formation for CaO-doping up to 2.0 mol%.CaO-doped(≥0.2 mol%)10Ce-TZP sintered at 1350℃ also highly resisted hydrothermal degradation.Furthermore,CaO-doping enabled to make Ce-TZP ceramics as translucent as different commercially available 3Y-TZP ceramics,opening possibilities to use Ce-TZP for dental restorations.
基金supported by the Key Project of the National Natural Science Foundation of China(Grant No.U21A2058)the Hebei Guoliang New Materials Co.,Ltd.(Grant No.22150239J).
文摘An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microstructure evolution and properties of magnesia–spinel refractories were characterized by the high-temperature elastic modulus,thermal shock damage resistance parameters,retainment of elastic modulus after thermal shock,and scanning electron microscopy.The results indicated that the incorporation of calcia-stabilized zirconia improved the thermomechanical properties and thermal shock behavior of magnesia–spinel specimens.The hot modulus of rupture of magnesia–spinel specimens increased by 2.5-fold due to the incorporation of calcia-stabilized zirconia micro-powder.The presence of a martensitic phase transformation in partially unstable ZrO2 and thermal mismatches among various phases contributed to a controlled formation of microcracks.And the pinning effect caused by the calcia-stabilized zirconia particles surrounding the grain boundaries played a crucial role in preventing the propagation of microcracks.This phenomenon significantly bolstered the thermal shock stability of magnesia–spinel refractories,consequently prolonging their service life.
文摘Aim To evaluate the interactive effects of different self- adhesive resin cements and tribochemical treatment on bond strength to zirconia. Methodology The following self-adhesive resin cements for bonding two zirconia blocks were evaluated： Maxcem （MA）, Smartcem （SM）, Rely X Unicem Aplicap （UN）, Breeze （BR）, Biscem （BI）, Set （SE）, and Clearfil SA luting （CL）. The specimens were grouped according to conditioning as follows： Group 1, polishing with 600 grit polishing paper; Group 2, silica coating with 110 μm Al2O3 particles which modified with silica; and, Group 3, tribochemical treatment - silica coating ＋ silanization. Specimens were stored in distilled water at 37℃ for 24 hours before testing shear bond strength. Results Silica coating and tribochemical treatment significantly increased the bond strength of the MA, UN, BR, B1, SE and CL to zirconia compared to #600 polishing. For both #600 polished and silica coating treatments, MDP- containing self-adhesive resin cement CL had the highest bond strengths to zirconia. Conclusion Applying silica coating and tribochemical treatment improved the bond strength of self-adhesive resin cement to zirconia, especially for CL.
