Accu Roll轧管机的背景、现状及前景

对Accu Roll轧管机的产生背景进行了回顾,对目前国内Accu Roll轧管机的使用现状进行了分析,在肯定其优点的同时,指出了该类轧管机存在的共同问题,提出了完善轧管机性能的可能途径及选择轧管机应注意的问题。     

TEMPERATURE DEPENDENCE ON HARDNESS AND EXPANSION OF SINTERED Nd-Fe-B MAGNETS

<正> Nd-Fe-B 合金,除用粉末冶金方法制备外,也用快淬、热压工艺制成具有优异性能的各向异性永磁体.实验表明,快淬 Nd-Fe-B合金的热压致密体于700℃下模压,若断面收缩达50%,则 Nd_2Fe_(14)B 基相的微晶因其 C 轴平行于压制方向而具有强的择优取向.显然,高温模压是用快淬合金制备高性能磁体的关键工艺,应变诱导晶粒长大和晶粒取向均在高温模压过程中完成.为探索快淬、热压磁体各向异性的成因,进而确定最佳热压工艺,有必要研究合金机械性     

国防生模拟连排建制管理的教育功能

依托普通高校培养军队干部是新时期我国国防建设的重大举措。本文针对普通高校如何完成该培养任务 ,在总结了中南大学国防生培养管理工作实践经验的基础上 ,提出了国防生模拟连排建制的管理模式 ,并对它的功能进行了具体分析。     

In situ technique for synthesizing multiple ceramic particulates reinforced titanium matrix composites (TiB + TiC + Y2O3)/Ti

In situ synthesized titanium matrix composites reinforced with multiple ceramic particulates including TiB, TiC and Y₂O₃ were fabricated by non-consumable arc-melting technique utilizing the chemical reaction among Ti, B₂O₃, B₄C and Y. The thermodynamic feasibility of the in situ reactions has been considered. X-ray diffraction (XRD) was used to identify the phases in the composites. Microstructures of the composites were observed by means of optical microscope (OM), scanning electron microscope (SEM) and electron probe. It is concluded that multiple reinforcements are synthesized and they show different shapes: TiB grows in needle shape; TiC grows in near-equiaxed and rod-like shapes; Y₂O₃ grows in near-equiaxed shapes when the content of Y is 0.6 wt.% and grows in dendritic shapes when the content of Y increases to 1.8 wt.%. Reinforcements TiB, TiC and Y₂O₃ are distributed uniformly in the titanium matrix.     

EXPERIMENTAL TESTING OF DRAW—BEAD RESTRAINING FORCE IN SHEET METAL FORMING

Due to complexities of draw-bead restraining force calculated according to theory and depending on sheet metal forming properties experiment testing system, a simplified method to calculate draw-bead restraining force is put forward by experimental method in cup-shaped drawing process. The experimental results were compared with numerical results and proved agreement. It shows the method is effective.     

NANO-MULTILAYERS WITH HIGH PERPENDICULAR ANISOTROPY FOR MAGNETIC RECORDING

(FePt/Ag)n nano-multilayers were deposited on MgO (100) single crystal with laser ablation and then subjected to annealing. FePt L1o grains with (001) texture and thus a large perpendicular magnetic anisotropy constant Ku of the order of 106 J/m3 were formed. A thick Ag layer is found to be favorable for decreasing the dispersion of the easy axis for magnetization. The measurement of time decay of magnetization gave rise to a small activation volume of the order of 10-25m3, showing the promising of being the recording medium for future high density perpendicular recording.     

MICROSTRUCTURE AND PROPERTIES OF C-Cu NANOSTRUCTURE THIN FILM

Nanostructured C-Cu thin films were deposited by reactive sputtering method and co-sputtering method. The relationships between microstructures, properties, and depo-sition parameters were studied and the results obtained from TEM, AFM, and XPS.indicate that the thin films are nanostructural, and have good in-depth uniformity. Theselected area electron diffraction (SAED) found that the nanosize Cu particles havethe fcc structure and the others are amorphous carbon or nanocrystallized graphiticcarbon. The peak positions of the Cu and C in XPS indicate them to be at the ele-mental state. In the IR transmission spectrum, diamond two-phonon absorption andgraphite Raman peaks were observed, which suggests microcrystal diamond particlesand graphite components exist in the C-Cu film. The higher electrical resistivity wasobtained.     

THERMAL DEMAGNETIZATION AND RANDOMNESS OF DOMAIN NUCLEATION OF SINGLE PHASE Nd_2 Fe_(14) B

Based on the observation of temperature variation of both domain structure and magnetic con-trast.the thermal demagnetization and randomness of domain nucleation was discussed.     

FORMING CONDITIONS AND GEOMETRICAL VARIETY OF ETCH FIGURES

本文以立方晶系中{100}型蚀坑为例,详细讨论了三种典型晶面(h00),(hk0)和(hkl)上出现的各类蚀坑的形成条件。给出了同类蚀坑几何多样性的判据,从而揭示了实际观察到的蚀坑几何多样性的根源。文中并提出了(hkl)面上蚀坑的复原及推演图解法。     

ROLE OF NITROGEN IN GRAIN ORIENTED SILICON STEEL CONTAINING Al

本文旨在确定Al,N含量在人们感兴趣的范围内与硅钢磁性的相关性。用热氢抽取法测定固溶氮和AlN中的氮,以阐明氮在含Al硅钢中的行为,并对以AlN为主要抑制剂的晶粒取向硅钢的工艺特性进行初步探讨。