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B-P-O系催化剂表面酸性的吸附量热研究 被引量:1
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作者 韩毓旺 沈俭一 陈懿 《物理化学学报》 SCIE CAS CSCD 北大核心 1997年第10期916-920,共5页
制备了不同P/B比的W-P-O系催化剂,XRD和Raman光谱表明各样品中P和B都处于四面体结构中,但Raman光谱显示P/B<1的样品表面有B的三配位物相B2O3。存在.用吸附量热法考察了NH3、H2O及二甲醚(DME)等探针分子的吸附行为,研究了样品... 制备了不同P/B比的W-P-O系催化剂,XRD和Raman光谱表明各样品中P和B都处于四面体结构中,但Raman光谱显示P/B<1的样品表面有B的三配位物相B2O3。存在.用吸附量热法考察了NH3、H2O及二甲醚(DME)等探针分子的吸附行为,研究了样品的表面酸性,NH3在P/B>1的样品上发生解离吸附,而在P/B<1的样品上,其起始吸附热与在γ-Al2O3上的相似.进一步的研究表明,二甲醚可以作为合适的探针分子表征B-P-O系催化剂的表面酸性. 展开更多
关键词 磷酸硼催化剂 表面酸性 吸附量热 探针分子选择
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Dual-Material Electron Beam Selective Melting:Hardware Development and Validation Studies 被引量:12
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作者 Chao Guo Wenjun Ge Feng Lin 《Engineering》 SCIE EI 2015年第1期124-130,共7页
Electron beam selective melting (EBSM) is an additive manufacturing technique that directly fabricates three-dimensional parts in a layerwise fashion by using an electron beam to scan and melt metal powder. In recen... Electron beam selective melting (EBSM) is an additive manufacturing technique that directly fabricates three-dimensional parts in a layerwise fashion by using an electron beam to scan and melt metal powder. In recent years, EBSM has been successfully used in the additive manufacturing of a variety of materials. Previous research focused on the EBSM process of a single material. In this study, a novel EBSM process capable of building a gradient structure with dual metal materials was developed, and a powder-supplying method based on vibration was put forward. Two different powders can be supplied individually and then mixed. Two materials were used in this study: Ti6AI4V powder and Ti47AI2Cr2Nb powder. Ti6AI4V has excellent strength and plasticity at room temperature, while Ti47AI2Cr2Nb has excellent performance at high temperature, but is very brittle. A Ti6AI4V/Ti47AI2Cr2Nb gradient material was successfully fabricated by the developed system. The microstructures and chemical compositions were characterized by optical microscopy, scanning microscopy, and electron microprobe analysis. Results showed that the interface thickness was about 300 μm. The interface was free of cracks, and the chemical compositions exhibited a staircase-like change within the interface. 展开更多
关键词 additive manufacturing electron beam selectivemelting gradient materials titanium alloy TiAI alloy
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