快速热压法制备掺杂纳米SiC的MgB_2超导体

采用快速热压烧结技术,在流动的高纯氩气保护氛围下,成功地制备出致密MgB2块材.系统地介绍了快速热压技术烧结MgB2块材的工艺,找出了烧结温度、保温时间、原料配比等最佳工艺参数;讨论了SiC纳米相的掺杂对MgB2块体的影响,包括微观显微组织、物相分析、临界电流密度(Jc)等.实验表明,在快速热压条件下,950℃保温30min,随后炉冷,可以制备出理想的MgB2块材,质量分数为5%SiC的掺杂可以极大地提高MgB2的超导性能.测试温度在20K以下,在自场下Jc可达到106A/cm2以上;在5K下,当外加磁场增加到7T时,Jc缓慢下降,但仍在105A/cm2以上,使其实用性得到更进一步改善.

Preparation of NanoSiC-Doped MgB_2 Bulk Superconductor by Rapid Hot Pressing Process

Compact MgB_2 bulks as superconductor were successfully prepared by rapid hot pressing process in high-purity flowing Ar protective atmosphere. Describes the rapid hot pressing-sintering process systematically, including such optimal process parameters as sintering temperature, holding time and mixture ratio of starting materials. Discusses the effects of nanoSiC doping on MgB_2 bulk in detail, such as microstructure, XRD pattern analysis and critical current density(J_c). It's found that the compact MgB_2 bulks can be prepared at 950 ℃ held for 30 min under hot pressing conditions. With furnace cooling followed, where the 5wt% nanoSiC doping performs an important role in improving the superconductivity. Moreover, J_c can be over 10~6 A/cm~2 in self-field if tested at 20 K and remains above 10~5 A/cm~2 at 5 K with the field intensity up to 7 T. The fact shows that the practicability of the preparing process has been improved.