纳米晶氧化镍的制备及表征

Nano-NiO powder was prepared by thermal decomposition of the precursor of NiC₂O₄·2H₂O obtained via Ni(NO₃)₂·6H₂O and H₂C₂O₄·2H₂O reacting in ethanol solvent. IR and TGA-DTA indicate physisorption and chem- isorption ethanol co-exist in the precursor. XRD suggests the obtained cubic NiO is stable below 700 ℃. TEM shows the as-calcined NiO at 400 ℃ for 2 hours was of narrow distribution, weak agglomeration and small particle size (average 8 nm). The reason for weak agglomeration was explained.     

Bi系超导材料的微波焊接及其显微结构研究

微波焊接技术近年来发展较快,它有下列优点:1)能耗低;2)升温速度快;3)接头质量高等。本文研究了Bi系超导材料微波焊接的可行性。结果表明,经855℃60h热处理后,焊接试样的T_c可达107K,与焊接前试样的T_c一致,焊区强度已经高于基体。利用电子探针对焊接前后的显微结构进行了比较,发现焊区组织致密,但在后处理过程中发生再结晶,导致焊区晶粒较大,焊缝变宽且焊区内存在较多杂相。 关键词：