等离子体辅助激光织构化预处理增强TiAlN刀具涂层膜基结合强度的机理研究

物理气相沉积(PVD)TiAlN涂层刀具在难加工材料高性能切削中有巨大的应用需求,而涂层膜基结合强度成为制约其高性能切削难加工材料的关键问题。为解决该问题,采用纳秒激光和等离子体刻蚀系统对硬质合金基体表面进行预处理,而后进行TiAlN涂层,最终获得传统涂层刀具(CCT)、激光织构化涂层刀具(LCT)、等离子体刻蚀涂层刀具(CECT)、等离子体辅助激光织构化涂层刀具(LECT)。分析织构化基体晶相结构、比表面积、表面能等材料特性和表面状态,并利用上述制备的涂层刀具进行划痕试验和干切削316奥氏体不锈钢试验。结果表明,通过基体表面等离子体辅助激光织构化预处理,可改善涂层膜基化学键合性能的差异,增加基体表面比表面积和表面能,改善膜基间物理结合和化学键合界面,进而提升TiAlN涂层膜基结合强度。与其他三种涂层刀具进行划痕试验与切削试验对比,进一步验证了LECT的涂层膜基结合强度最好。

等离子体织构化的n-Si与P3HT组成杂化太阳能电池的性能研究

在容性耦合SF6/O2等离子体织构化处理的单晶Si衬底上旋涂P3HT(poly(3-hexylthiophene))以制作杂化太阳能电池,研究不同激发频率下得到的晶硅表面纳米织构对该杂化电池性能的影响。实验结果表明:激发频率的增大促使了电池表面反射率的降低,增强了杂化电池的光电转化效率。40.68 MHz激发频率下等离子体织构处理的单晶Si制成的杂化电池光电转换效率达到1.14%。此外,空气中存放时间对电池片性能影响的研究表明40.68 MHz织构的硅/P3HT杂化电池片具有较好的电池特性和稳定性。

Microstructure and mechanical properties of TiAl-based alloy prepared by double mechanical milling and spark plasma sintering

A fine-grained TiAl alloy with a composition of Ti-45Al-2Cr-2Nb-1B-0.5Ta-0.225Y （mole fraction, %） was prepared by double mechanical milling（DMM） and spark plasma sintering（SPS）. The relationship among sintering temperature, microstructure and mechanical properties was studied. The results show that the morphology of double mechanical milled powder is regular with size in the range of 20-40 μm and mainly composed of TiAl and Ti3Al phases. The main phase TiAl and few phases Ti3Al, Ti2Al and TiB2 were observed in the SPSed alloys. For samples sintered at 900 ℃ the equiaxed crystal grain microstructure is achieved with size in the range of 100-200 nm. With increasing the SPS temperature from 900 ℃to 1000 ℃ the size of equiaxed crystal grain obviously increases, the microhardness decreases from HV658 to HV616, and the bending strength decreases from 781 MPa to 652 MPa. In the meantime, the compression fracture strength also decreases from 2769 MPa to 2669 MPa, and the strain to fracture in compression increases from 11.69% to 17.76%. On the base of analysis of fractographies, it shows that the compression fracture transform of the SPSed alloys is intergranular rupture.

Study on Bombyx mori silk treated by oxygen plasma

Study of the morphology, aggregation structure and properties ofBombyx mori silk treated by low temperature oxygen plasma showed that slight flutes appeared on the surface of Bombyx mori silk fiber and that its surface structure changed after plasma treatment. The conformation also changed and crystalline degree decreased. The stannic filling rate of treated fiber was improved. Because of etching, the weight of the fiber decreased but the breaking strength changed little after short-time treatment.

抑制多级降压收集极二次电子发射的研究进展

简述了热解石墨、高纯各向同性石墨和无氧铜材料的二次电子发射特性,以及离子束表面改性对二次电子发射特性的影响。分析表明热解石墨和高纯各向同性石墨的二次电子发射系数均明显低于无氧铜的二次电子发射系数,并且通过离子束表面改性后二次电子发射系数能够得到进一步的降低。同样的,离子束表面改性后的无氧铜的二次电子发射系数也得到一定的降低,并且还有很大的发展空间。