快速热压法制备掺杂纳米SiC的MgB_2超导体

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

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.

Compact MgB2 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 MgB2 bulk in detail, such as microstructure, XRD pattern analysis and critical current density（Jc）. It＇s found that the compact MgB2 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, Jc can be over 106 A/cm^2 in self-field if tested at 20 K and remains above 105 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.