导热填料对HDPE/石蜡定形相变材料性能的影响

采用熔融共混技术,在高密度聚乙烯（HDPE）/石蜡定形相变材料中添加普通石墨、氧化膨胀石墨、超声膨胀石墨以及膨胀石墨（EG）4种导热填料制备导热定形相变材料（PCM）。SEM图表明导热填料可以与HDPE、石蜡均匀混合。添加导热填料后定形相变材料的渗漏率有增大的趋势,但添加普通石墨和超声膨胀石墨时,渗漏率随导热填料含量的增加而增加,添加氧化膨胀石墨和EG时,PCM的渗漏率随导热填料含量的增加而降低。定形相变材料中添加导热填料时其热导率有显著提高。添加EG时,定形相变材料的热导率提高最多,提高率达144.7%。     

Evaluation method of cracking resistance of lightweight aggregate concrete

The cracking behavior of lightweight aggregate concrete（LWAC） was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete（NWAC）. A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt（t） and the evaluation index Acr（t） were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr（t） is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr（t） is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.     

超临界乙醇制备TiO_2/石墨烯纳米复合材料及其表征

以氧化石墨为载体、钛酸异丙酯为前驱体,利用超临界乙醇的超临界性能和还原性,制得了晶型完善的锐钛矿TiO2/石墨烯纳米复合材料。通过红外光谱(FTIR)、X射线光电子能谱(XPS)对采用Hummers法制得的氧化石墨(GO)进行表征;同时利用透射电子显微镜(TEM)、X射线衍射仪(XRD)对TiO2/石墨烯纳米复合材料进行研究。结果表明:成功制得了氧化石墨(GO)和晶型完善的锐钛矿TiO2/石墨烯纳米复合材料,并且发现二氧化钛在石墨烯纳米片层上呈现为有规则的颗粒,分散均匀,平均粒径为8.24nm。     

光电跟踪转台有限元模态分析

为了分析计算光电跟踪转台的模态以及振型,利用ANSYS有限元分析软件计算了光电跟踪转台的3阶模态,分析了整体结构以及各部件之间的刚性连接,在计算固有频率时对结构进行了简化.通过对结构进行模态分析,得出该结构的固有频率与振型,得出了结构在此频率范围内受外界或自身激励的影响规律.计算结果表明:1阶固有频率为93.16 Hz,2阶固有频率为100.84Hz,3阶固有频率为105.71Hz;外界激励频率在10~60Hz,可以避免结构发生共振.     

预制法制备四聚脲润滑脂的工艺研究

考察了预制法制备工艺条件对四聚脲润滑脂性能的影响,优化了制备工艺,并探讨了制备过程机理,阐述了润滑脂宏观性能与微观结构之间的关系。优化的工艺条件及制备过程为：在50～70℃下反应30 min后得到四脲稠化剂;将四脲稠化剂加入到基础油中,搅拌并升温至170～180℃,恒温炼制1.5h,冷却、研磨均化,得到四聚脲润滑脂。润滑脂性能分析结果表明,由轻度精制环烷基基础油、质量分数20%四脲稠化剂、质量分数0.8%极压抗磨剂制备的四聚脲润滑脂,滴点达320℃,工作锥入度为286(0.1 mm),钢网分油率为0.86%,且其他性能均满足极压聚脲脂质量标准SH/T0789—2007的要求。     

2-乙酰柠檬酸三丁酯对苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物性能的影响

将2-乙酰柠檬酸三丁酯（ATBC）添加到苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物（SEBS）中对其进行改性,研究了改性后SEBS的化学结构、力学性能及热性能。结果表明,使用ATBC对SEBS进行改性不改变SEBS的链结构,但会使SEBS的拉伸强度和直角撕裂强度降低、扯断伸长率增大、玻璃化转变温度和结晶度下降。结晶度下降是造成ATBC改性SEBS拉伸强度和直角撕裂性能变差的主要原因。     

天然橡胶生物合成分子调控机制的研究进展

天然橡胶(NR)生物合成的精确调控机制解析是尚未攻克的重要理论问题。综述产胶植物基因组和NR生物合成过程相关基因的调控机制,重点阐述小橡胶粒子蛋白质基因在产胶植物的橡胶合成过程中作用的研究进展,为NR生物合成分子机制以及分子育种研究提供理论参考。指出NR生物合成调控机制的研究与收获技术和提取工艺技术相结合,有助于解析产胶植物的NR合成机制和提高其产胶量。     

稀土对切玻璃金刚石锯片切削性能的影响

金刚石圆锯片可以用于切割玻璃和水晶制品。为了提高切割玻璃金刚石圆锯片的切割寿命和玻璃的切割质量．对切割玻璃金刚石圆锯片的胎体成分进行了优化设计，并在胎体材料中加入稀土化合物La2O3，同时对金刚石表面实施镀钛。本文从胎体材料对金刚石的把持力系数、实际切割的金刚石的脱落度以及锯片的切割速度方面，研究了稀土化合物在金刚石刀头胎体中的作用。结果表明：在胎体金属粉中加入适量的稀土化合物，胎体对金刚石的把持力系数有所改善，同时，增加了刀头胎体材料的脆性，实现了金刚石与胎体的同步磨损，金刚石的脱落度明显减小；切割速度比参比片提高了21．6％。     

碳热法合成具有蓝光发射特性的氧化镓纳米线、纳米带和纳米片

利用碳纳米管通过碳热法合成了氧化镓纳米线、纳米带和纳米片。采用扫描电镜和透射电镜对其进行了形态和结构表征。合成的氧化镓纳米结构是单晶体。室温光致发光谱分析发现，氧化镓纳米晶在蓝光区域487nm处产生明显的发射峰。     

Interfacial microstructure of 20% SO2/Al matrix composites reinforced with in situ formation ceramic phases

Al matrix composites reinforced with in situ ceramic phases by adding 20% SiO2 were fabricated by powder metallurgy process.The interfacial microstructure of the composites was studied by means of SEM and HREM.It was shown that the ceramic phases mainly composed of spinel MgAl2O4 are formed in situ in the original SiO2 particle and the size of small MgAl2O4 crystallites is about dozens of nanometers,which can adjacent to Al and Si.MgO could not found in original SiO2 particle but a little in matrix and may exist with Si,Mg2Si and Al.Si is mostly distributed in matrix and forms some segregation zones.The size of Mg2Si is about 50-100nm and can usually be seen in the matrix.