Fabrication of nano Rhizama Chuanxiong particles and determination of tetramethylpyrazine

Rhizama Chuanxiong is a kind of traditional medicinal herb used to promote blood circulation and eliminate wind to relieve pain. In this work, nano Rhizoma Chuanxiong particles were successfully prepared by high speed centrifugal sheering （HSCS） pulverizer. The influence of processing parameters on the size ofRhizama Chuanxiong particles and the different properties between nano Rhizoma Chuanxiong particles and original fine powder were systematically studied by ZetaPALS light scattering granulometric analyzer and optical microscope. The content of effective ingredient tetramethylpyrazine （TMP） was determined by high-performance liquid chromatography （HPLC）. The results illustrate that general Rhizama Chuanxiong powder can be ultrafinely ground to nanometer within 50 min, and the cellular tissues ofRhizoma Chuanxiong are broken into pieces and dispersed stably and homogeneously after being ultrafinely ground. In addition, the active ingredients can dissolve out directly and fully, and the extraction ratio of TMP is increased 32.2% by HSCS processing.     

Diffusion bonding of Ti-6Al-4V by pulse current heating and hot-pressing

Pulse current heating （PCH） was used to join Ti-6Al-4V alloy at two cases of with die and without die. Hot-pressing （HP） method was used to provide a comparison between the two methods. Microstructures near the contacting surfaces were observed in optical microscope. Temperature distribution was analyzed. After joining, the tensile properties of the samples were evaluated. Experimental results show that grains and phases grow transversely on contacting surfaces, which makes two parts into a whole with a certain of tensile strength. PCH joining is a different temperature joining method. The highest temperature is located at the interface. The comparison of tensile strengths of samples joined by the two methods indicates that joining temperature and holding time needed by PCH are lower and less than those needed for HP.     

自蔓延高温合成细晶六硼化钙陶瓷粉末(英文)

基于Mg–B2O3–CaO原料体系,采用自蔓延高温合成(self-propagating high-temperature synthesis,SHS)和后期酸处理工艺,制备出高纯度、均匀分布、小粒径的立方晶型细晶六硼化钙粉末。分析了Mg–B2O3–CaO自蔓延高温反应体系的燃烧产物成分及反应机理,测量了不同SHS反应物原始坯体成型压力的燃烧温度曲线,探讨了不同镁掺量和不同气氛对燃烧产物成分和形貌的影响。研究了原始坯体成型压力与最终CaB6产物粒径的关系。结果表明:采用氩气保护能抑制镁挥发;合适的原始坯体压力有利于合成分布均匀的细晶CaB6粉末。     

Fabrication of TiB2 composite powders coated with BN by high speed airflow impact

TiB2 powders coated with BN were prepared by Hybridization System making use of dry impact blending method to achieve powder surface modification. Parameters of coating were analyzed and the most appropriate condition was summarized. Scan electron microscope of JSM-5610LV and transmission electron microscope of H600STEM/EDS were used to observe the microstructure of coated powders. Results show that treatment time, rotation speed, granularity ratio of TiB2 to BN, pretreatment of materials etc influence the coating results evidently.Mixing raw materials and coating with BN under the appropriate condition can get round TiB2/BN composite powder with smooth surface and compact coating layer.     

层状复合陶瓷研究进展

综合评述了层状复合陶瓷的一些研究进展，同时讨论了层状复合陶瓷的断裂特性，包括几种主要的增韧机制和影响因素。最后，对如何设计层状陶瓷作了一个总结！     

用放电等离子技术烧结TiB2陶瓷

利用脉冲大电流快速烧结技术（也称放电等离子烧结SPS技术）研究了TiB2的烧结过程。结果表明：升温速率对烧结样品的相对密度、晶粒尺寸及烧结过程中真空室气压均有重要影响。最佳的升温速率使TiB2烧结晶粒相对最小、烧结体相对密度较高。分析认为，在SPS条件下的快速升温有利于颗粒表面活化，烧结体晶粒尺寸既受控于烧结时间，也受控于晶粒生长活化能。     

高活性B_4C-SiC超细复合粉体的制备及烧结

以B4C、SiC粗粉为原料,采用机械合金化制备高活性的B4C-SiC超细复合粉体。通过XRD、SEM、LPSA和IR等测试技术研究球料比、过程控制剂及球磨时间对复合粉体性能的影响,确定机械合金化制备B4C-SiC超细复合粉体的最佳工艺条件,研究机械合金化过程中粉体有序-无序转变过程。随后,采用热压烧结工艺验证复合粉体的烧结活性。结果表明:球磨机转速是250 r/min的条件下,球料比为30:1,过程控制剂为2wt%,球磨时间为120 h时,可获得晶格无序的B4C-50wt%SiC超细复合粉体;该复合粉体在1900℃,30 MPa热压条件下烧结1 h,其体积密度为2.62 g/cm3,达到理论密度的93%,比普通混合粉体在相同热压条件下获得样品的致密度提高了8.1%;机械合金化工艺制备的B4C-SiC超细复合粉体具有极高的烧结活性。     

试述永磁材料及软磁材料的研究进展

永磁材料和软磁材料是磁性材料中的两大类主要磁性材料，本文在综述磁性材料的基础上，较详细地阐述了永磁材料和软磁材料在国内外的研究进展情况，并展望了其发展趋势。     

导电体与绝缘体复相陶瓷中的渗流现象

导电体与绝缘体复相陶瓷的导电性能符合渗流理论，其渗流转变曲线受多种因素的影响，除导电相与绝缘相二相组成的配比外，还受到二相颗粒的尺寸、形状及分布的影响，复相陶瓷的烧成温度、温度制度影响了临界指数、晶粒粒径比及晶界层，从而也影响渗流转变曲线。