Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Z...Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Zr0.5Ti0.5Al0.5O2 catalysts was evaluated using the simulated gases. The results show that ZTA samples exhibit higher specific surface area,larger pore volume and proper surface acidic amount and acidity in comparison with ZT. The results of the catalytic test indicate that Pt/ZT and Pt/ZTA catalysts exhibit excellent low-temperature catalytic activity and lower light-off temperatures of hydrocarbon,carbon monoxide and nitrogen oxides,especially better conversion for nitrogen oxides (NOx). The addition of Al2O3 into ZT enhanced the anti-aging property of Pt/ ZTA catalysts due to the excellent textural,structural,surface acidity and thermal stability.展开更多
Al2O3 and Ti-6Al-4V alloy were brazed with Ag-Cu-Ti ＋B fillers in different brazing conditions. Effects of brazing temperature, holding time and additive Ti content on joints microstructure and shear strength were in...Al2O3 and Ti-6Al-4V alloy were brazed with Ag-Cu-Ti ＋B fillers in different brazing conditions. Effects of brazing temperature, holding time and additive Ti content on joints microstructure and shear strength were investigated by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, transmission electron microscopy and shear testing. Results indicate that TiCu and Ti（Cu,Al） decrease, but Ti2Cu and -Ti2（Cu,Al） increase in brazing seam with increasing brazing temperature, holding time and additive Ti content. Area consisting of Ti3（Cu,Al）30 and TiO near Al2O3 becomes gradually discontinuous from continuity when brazing temperature rises or holding time extends. As Ti additive content increases, TiO is absent near Al2O3, area consisting of only Ti3（Cu,Al）30 thickens. TiB whiskers are in situ synthesized by Ti and B atoms during brazing process. The brazing temperature, holding time and additive Ti content on joints microstructure influence the joints shear strength directly. The shear strength of joints, obtained at 850 ℃ holding for 10 min, reaches the maximum of 78 MPa. According to the experimental results, phase diagram and thermodynamics calculation, the interface evolution mechanism of the Al2O3/Ti-6Al-4V alloy joint was analyzed.展开更多
In the present study, it is expected to tailor the microstructural features, martensitic transformation temperatures and mechanical properties of Ti-V-Al shape memory alloys through adding Sn alloying elements, which ...In the present study, it is expected to tailor the microstructural features, martensitic transformation temperatures and mechanical properties of Ti-V-Al shape memory alloys through adding Sn alloying elements, which further expands their applications. Sn addition results in the monotonous rising of average valence electron number (e/a). In proportion, the single α″ martensite phase directly evolves into merely β parent phase in present Ti-V-Al-based shape memory alloys, as Sn content increases from 0.5 to 5.0 at.%. Meanwhile, Sn addition causes the reduction in the grain size. Combined with transmission electron microscopy (TEM) observation and d electron theory analysis, it can be speculated that Sn addition can suppress the precipitation of ω phase. With increasing Sn content, fracture strength invariably decreases from 962 to 792 MPa, whereas the yield strength firstly decreases and then increases. The lowest yield stress for the stress-induced martensitic transformation of 220 MPa can be obtained in Ti-V-Al shape memory alloy by adding 3.0 at.% Sn. By optimizing 1.0 at.% Sn, the excellent ductility with a largest elongation of 42.1% can be gained in Ti-V-Al shape memory alloy, which is larger than that of the reported Ti-V-Al-based shape memory alloys. Besides, as a result of solution strengthening and grain refinement, Ti-V-Al-based shape memory alloy with 5.0 at.% Sn possesses the highest yield strength, further contributing to the excellent strain recovery characteristics with 4% fully recoverable strain.展开更多
以TiO_2-Al_2O_3复合物为载体,采用浸渍法负载金属Ni制备了Ni/TiO_2-Al_2O_3裂解汽油预加氢催化剂(YN-1型)。针对裂解C_9^+原料在实验室200 m L加氢小试装置上进行了评价,并在新疆独山子天利实业总公司裂解C_9^+预加氢装置上对该催化剂...以TiO_2-Al_2O_3复合物为载体,采用浸渍法负载金属Ni制备了Ni/TiO_2-Al_2O_3裂解汽油预加氢催化剂(YN-1型)。针对裂解C_9^+原料在实验室200 m L加氢小试装置上进行了评价,并在新疆独山子天利实业总公司裂解C_9^+预加氢装置上对该催化剂进行了工业应用。实验室评价结果表明,YN-1型催化剂用于裂解C_9^+原料一段加氢,不但具有良好的低温加氢活性和选择性,且稳定性良好;工业应用结果表明,在反应器入口温度远低于设计温度的条件下,对于胶质含量(基于100 m L原料油)大于100 mg和溴价(基于100 g原料油)大于95 g的裂解C_9^+原料进行预加氢,装置操作平稳,催化剂床层未出现飞温现象,催化剂能够适应超过90℃的反应温升;加氢产品中苯乙烯类芳烃、二烯烃、双环二烯烃和茚的含量(w)比原料分别下降了75.51%,91.00%,85.51%,56.64%,且芳烃没有损失。展开更多
文摘Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Zr0.5Ti0.5Al0.5O2 catalysts was evaluated using the simulated gases. The results show that ZTA samples exhibit higher specific surface area,larger pore volume and proper surface acidic amount and acidity in comparison with ZT. The results of the catalytic test indicate that Pt/ZT and Pt/ZTA catalysts exhibit excellent low-temperature catalytic activity and lower light-off temperatures of hydrocarbon,carbon monoxide and nitrogen oxides,especially better conversion for nitrogen oxides (NOx). The addition of Al2O3 into ZT enhanced the anti-aging property of Pt/ ZTA catalysts due to the excellent textural,structural,surface acidity and thermal stability.
基金the National Natural Science Foundation of China (Grant Nos.51275135,51105107 and 51021002)the Natural Science Foundation of Heilongjiang Province,China (Grant No.QC2011C044)the Specialized Research Fund for the Doctoral Program of Higher Education,China (Grant No.20112302130005)
文摘Al2O3 and Ti-6Al-4V alloy were brazed with Ag-Cu-Ti ＋B fillers in different brazing conditions. Effects of brazing temperature, holding time and additive Ti content on joints microstructure and shear strength were investigated by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, transmission electron microscopy and shear testing. Results indicate that TiCu and Ti（Cu,Al） decrease, but Ti2Cu and -Ti2（Cu,Al） increase in brazing seam with increasing brazing temperature, holding time and additive Ti content. Area consisting of Ti3（Cu,Al）30 and TiO near Al2O3 becomes gradually discontinuous from continuity when brazing temperature rises or holding time extends. As Ti additive content increases, TiO is absent near Al2O3, area consisting of only Ti3（Cu,Al）30 thickens. TiB whiskers are in situ synthesized by Ti and B atoms during brazing process. The brazing temperature, holding time and additive Ti content on joints microstructure influence the joints shear strength directly. The shear strength of joints, obtained at 850 ℃ holding for 10 min, reaches the maximum of 78 MPa. According to the experimental results, phase diagram and thermodynamics calculation, the interface evolution mechanism of the Al2O3/Ti-6Al-4V alloy joint was analyzed.
基金financial support from the National Natural Science Foundation of China(Nos.52101231,52101232 and 51871079)the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing(Yantai)(No.AMGM2021F09)+1 种基金the Natural Science Foundation of Shandong Province,China(No.ZR2021QE044)the Gansu Province Science and Technology Foundation for Youths(No.21JR7RA088).
文摘In the present study, it is expected to tailor the microstructural features, martensitic transformation temperatures and mechanical properties of Ti-V-Al shape memory alloys through adding Sn alloying elements, which further expands their applications. Sn addition results in the monotonous rising of average valence electron number (e/a). In proportion, the single α″ martensite phase directly evolves into merely β parent phase in present Ti-V-Al-based shape memory alloys, as Sn content increases from 0.5 to 5.0 at.%. Meanwhile, Sn addition causes the reduction in the grain size. Combined with transmission electron microscopy (TEM) observation and d electron theory analysis, it can be speculated that Sn addition can suppress the precipitation of ω phase. With increasing Sn content, fracture strength invariably decreases from 962 to 792 MPa, whereas the yield strength firstly decreases and then increases. The lowest yield stress for the stress-induced martensitic transformation of 220 MPa can be obtained in Ti-V-Al shape memory alloy by adding 3.0 at.% Sn. By optimizing 1.0 at.% Sn, the excellent ductility with a largest elongation of 42.1% can be gained in Ti-V-Al shape memory alloy, which is larger than that of the reported Ti-V-Al-based shape memory alloys. Besides, as a result of solution strengthening and grain refinement, Ti-V-Al-based shape memory alloy with 5.0 at.% Sn possesses the highest yield strength, further contributing to the excellent strain recovery characteristics with 4% fully recoverable strain.
文摘以TiO_2-Al_2O_3复合物为载体,采用浸渍法负载金属Ni制备了Ni/TiO_2-Al_2O_3裂解汽油预加氢催化剂(YN-1型)。针对裂解C_9^+原料在实验室200 m L加氢小试装置上进行了评价,并在新疆独山子天利实业总公司裂解C_9^+预加氢装置上对该催化剂进行了工业应用。实验室评价结果表明,YN-1型催化剂用于裂解C_9^+原料一段加氢,不但具有良好的低温加氢活性和选择性,且稳定性良好;工业应用结果表明,在反应器入口温度远低于设计温度的条件下,对于胶质含量(基于100 m L原料油)大于100 mg和溴价(基于100 g原料油)大于95 g的裂解C_9^+原料进行预加氢,装置操作平稳,催化剂床层未出现飞温现象,催化剂能够适应超过90℃的反应温升;加氢产品中苯乙烯类芳烃、二烯烃、双环二烯烃和茚的含量(w)比原料分别下降了75.51%,91.00%,85.51%,56.64%,且芳烃没有损失。
