RELATIONSHIP OF THE PROPERTIES OF HOT－PRESSING C－BC_4－SiC COMPOSITE WITH THE CONTENT OF ADDITIVE Al

ＲＥＬＡＴＩＯＮＳＨＩＰＯＦＴＨＥＰＲＯＰＥＲＴＩＥＳＯＦＨＯＴ－ＰＲＥＳＳＩＮＧＣ－ＢＣ_４－ＳｉＣＣＯＭＰＯＳＩＴＥＷＩＴＨＴＨＥＣＯＮＴＥＮＴＯＦＡＤＤＩＴＩＶＥＡｌ￥Ｈｕａｎｇ，Ｑｉｚｈｏｎｇ；Ｔａｎ，Ｐｉｎｇ；Ｙａｎｇ，Ｑｉａｏｑｉｎ＋；Ｈ?..     

Ni对C－B_4C－SiC复合材料显微结构与性能的影响

本文研究了烧结助剂Ｎｉ对Ｃ－Ｂ_４Ｃ－ＳｉＣ复合材料显微结构与性能的影响．Ｘ射线衍射表明Ｎｉ在烧结温度下与ＳｉＣ，Ｂ_４Ｃ人发生反应在晶界生成Ｎｉ_（４．６）Ｓｉ_２Ｂ，并产生液相，有效地促进了Ｃ－Ｂ_４Ｃ－ＳｉＣ复合材料的烧结，抑制了晶粒的长大，使复合材料密度与强度大幅度地增加，电阻率下降；同时Ｎｉ_（４．６）Ｓｉ_２Ｂ在氧化时生成致密的２ＮｉＯ·Ｂ_２Ｏ_３，包裹了易氧化的Ｂ_４Ｃ和Ｃ，有效地防止了复合材料的氧化，从而大大提高了制品的抗氧化性能．     

预制装配式梁板桥板缝错台的成因和预防

预应力钢筋混凝土空心梁板在我国桥梁界有着广泛的应用,其矩形横断面和结构特征决定了相邻2片梁板紧挨着安装,2片梁板底水平间距只有10 mm。在预应力钢筋混凝土空心梁板简支结构桥梁中,经常会出现相邻梁板板缝错台问题,高差较大时在后续的梁板勾缝工序中难以衬平弥补,从而影响桥梁外观质量,特别是在城市跨线互通桥梁上这种影响尤为严重。     

金刚石涂层超精加工车刀的研制

使用热丝ＣＶＤ法研究了金刚石涂层生长速度、晶粒大小和结合强度与生长工艺参数的关系，在此研究基础上，选择氮化硅材料作为刀具基底材料，并优化生长工艺参数，使热丝ＣＶＤ法生长金刚石膜的速度提高到２０μｍ／ｈ，膜层平均晶粒度〈１μｍ，划痕临界载荷达到了５０Ｎ，然后进行内应力消除及机械研磨、抛光，这样制成的超精加工刀具有来加工铝合金部件。被加工件的表面不平度〈０．１μｍ，光洁度达到了△↓１２，加工光洁度与寿     

Y-Ba-Cu-O超导涂层的研制

用等离子喷涂工艺制备了 Y-Ba-Cu-O 高临界温度超导涂层,涂层的初始转变温度为101K、零电阻温度为86K。电阻率与磁化率的测量结果表明这种超导涂层具有与烧结超导块体相类似的性能,X 光衍射谱显示出涂层主要由 YBa_2Cu_3O_(?)单相化合物组成。     

问题启发与专题研讨相结合的材料类研究生教学新模式

随着研究生招生规模的不断扩大,研究生教育质量逐渐成为关注的焦点。为了保证和提高研究生的培养质量,以材料类研究生培养过程为例,引入问题启发为中心的学习方法和专题研讨相结合的教学方法,分析了在材料类研究生培养过程中两种学习方法的结合和操作过程的注意点,进一步给出研究生教与学过程中运用两种方法的建议。     

CVD growth of secondary carbon nanotubes and its effect on field electron emission

Secondary carbon nanotubes (CNTs) were grown on primary ones by simply changing the methane concentration. No additional catalyst was used throughout the whole deposition process. The CNT growth was carried out using hot filament chemical vapor deposition in a gas mixture of methane and hydrogen. The structure and surface morphology of the deposited CNTs were studied and the field emission properties of the CNTs were tested. It was found that synthesizing primary CNTs at extremely low methane concentration is the key for the secondary growth without additional catalyst. The CNT samples grown with secondary nanotubes exhibited improved field emission properties.     

Cloning and Expression of Aspergillus tamarii FS132 Lipase Gene in Pichia pastoris

A lipase gene (atl) was cloned from Aspergillus tamarii FS132 for the first time. The gene was found to have an open reading frame of 1024 base pairs (bp), and the coding region of the gene contained two introns (51 bp and 52 bp). Multi-alignment analysis of the deduced amino acid sequence indicated high homology between the enzyme and mono-and diacylglycerol lipases from fungi Aspergillus. The recombinant lipase was expressed in Pichia pastoris GS115 cells. The recombinant lipase was found to have a molecular mass of 36.7 kDa, and it exhibited lipase activity of 20 U/mL in culture supernatant when tributyrin was used as the substrate.     

SiC和SiC-WC复相陶瓷高温自润滑特性及其机理

研究了SiC和SiC-WC在真空中的自对偶高温摩擦性能。随着温度的升高，SiC／SiC的摩擦系数变化不大，比磨损率(自对偶体积磨损量与接触压力和摩擦路程之比)从20℃到800℃保持为4.0×10~(-8) mm~3／(N·mm)(模式Ⅰ)，从800℃到1 200℃减少(模式Ⅱ)，自对偶的高温磨损机理由轻微的粘着磨损控制，磨损由模式Ⅰ向模式Ⅱ转化，呈现出高温自润滑特性。SiC-WC／SiC-WC显示了较低的摩擦系数，直到1 200℃均不高于0.35，在1 000℃、0.4 MPa压力下自对偶的比磨损率仅为SiC／SiC的比磨损率的50％左右。在600℃SiC／SiC摩擦氧化明显，氧化物主要为无定形的SiO_2，在摩擦表面形成一层由微米或亚微米级无定形平滑薄膜层，这就是样品出现自润滑的机理。