Unique microstructure of porous NiAl intermetallic compound prepared by combustion synthesis

Porous NiAl intermetallic compounds have been prepared by combustion synthesis from nickel and aluminum elemental powders. The synthesis process, pore structure and pore forming mechanism were studied systematically. The results show that porous intermetallic compounds are composed of single NiAl phase, which have unique feature of complex pore structure, i.e. micro-pores are distributed in the wall of macro-pores and small pores. It has been found that different pores are formed in different stages. The macro-pores are formed by the volatilization of pore-forming agent at preheating stage. Due to the kirkendall effect and molten Al to cover the surface of Ni particles by capillary force, small pores are formed during the reaction. The shape and the size of small pores depend largely on the Al particles. However, the formation of micro-pores in the unique complex pore structure mainly contributes to the liquid of Al and part of NiAl accompanied by liquid?Csolid reaction of Ni?CAl at the cooling stage, which is different from the kirkendall pores.     

Synthesis, Crystal Structures and Fluorescence Properties of Two One-Dimensional Cadmium(II) Coordination Polymers Containing Flexible Bis(benzimidazole) Ligands

Two one-dimensional Cd(II) coordination polymers constructed by ribbon-like molecules, {[Cd(L₁)₂(NO₃)]·NO₃} _n (1) (L₁ = 1,3-bis(5,6-dimethylbenzimidazol-1-yl)benzene) and [Cd(L₂)₂(NO₃)₂] _n (2) (L₂ = 1,3-bis(benzimidazol-1-yl)benzene) have been obtained through assembly of the two structurally similar flexible bis(benzimidazole)-based ligands and cadmium nitrate tetrahydrate. The cadmium(II) centers display different coordination environments with trigonal-bipyramidal geometry in 1, and a octahedral geometry in 2. Weak C–H···O interactions in 1 result in a two-dimensional supramolecular layer; two π–π interactions are present in 2 forming a three-dimensional supramolecular network structure. The solid state fluorescence properties of 1 and 2 were investigated.     

乳液型丙烯酸酯压敏胶的研究

以丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)和丙烯酸(AA)为反应单体,过硫酸铵(APS)为引发剂,非离子型乳化剂(OP-10)/十二烷基硫酸钠(SDS)为复合乳化剂,硫酸铝为化学交联剂,采用乳液聚合法合成了丙烯酸酯PSA(压敏胶)。研究结果表明:当w(BA)=80%、w(MMA)=14%、w(AA)=6%、w(APS)=0.4%、w(硫酸铝)=2.0%、w(复合乳化剂)=6%且m(OP-10)∶m(SDS)=2∶1时,相应PSA的固含量(54.41%)较高、黏度(140 mPa.s)较低以及耐热性良好,并且其180°剥离强度(2.79 N/mm)、初粘力(16号钢球)和持粘力(>24.0 h)俱佳。     

电熔镁砂加入量对钢包用铝镁质透气砖性能的影响

为了实现钢包用透气砖的无铬化,以板状刚玉(6～3、3～1、≤1mm)为骨料,板状刚玉细粉(≤0.044mm)、α-Al2O3微粉(≤5μm,d50=2.01μm)、镁铝尖晶石细粉(≤0.044mm)、电熔镁砂细粉(≤0.044mm)为基质,以纯铝酸盐水泥为结合剂,将骨料和基质的质量比固定为70:30,通过研究电熔镁砂细粉加入量(其质量分数1％、2％、3％、4％、5％)对铝镁质透气砖性能的影响,研制了铝镁质透气砖,与铬刚玉质透气砖的性能进行了对比.结果表明:加入质量分数2％的电熔镁砂细粉,试样的力学性能提高,抗热震性增强;进一步增大电熔镁砂细粉的加入量,由于原位镁铝尖晶石的生成量过多,微裂纹发展成为破坏性裂纹,试样的强度急剧降低,体积密度下降,试样的加热永久线变化增大,抗热震性先增强后减小,高温抗折强度下降.通过铬刚玉质透气砖和铝镁质透气砖性能及现场试用情况的对比,认为铝镁质透气砖可代替铬刚玉质透气砖使用,实现透气砖的无铬化.     

师范院校分析化学实验教学改革实践与探索

分析了师范院校分析化学实验教学中存在的问题,从教师和学生两方面进行剖析,建立了开放式和因材施教的教学模式,采用了多元化的考核体系,加强了学生的学习动机,培养了学生的实践能力,形成了自主创新的教学特色。     

水性聚氨酯分散体制备技术的研究

以异佛尔酮二异氰酸酯（IPDI）、甲苯-2,4-二异氰酸酯（TDI）、聚碳酸酯二醇（L5652—2000）和聚四氢呋喃二醇（PTMG-2000）为主要原料,2,2-二羟甲基丙酸（DMPA）为亲水单体,1,4-丁二醇（BDO）和乙二胺（EA）为扩链剂,在不同条件下制备了系列水性聚氨酯分散体。通过对胶膜硬度、吸水率以及附着力等的研究,分析了分子结构及分散条件对分散体稳定性和胶膜性能的影响。     

辊压机行星减速器主要承载部件的有限元分析

对中国重型机械研究院有限公司研发、生产的900kW（PBZF900—80）大功率行星减速器的关键承载零部件——行星架部件、壳体部件进行了有限元分析。结果表明：（1）最大应力均没有超过其材料的屈服极限,其变形值也小于所用材料许用值;（2）此法用于大功率、大扭矩减速器的设计是可行的。     

尿素装置高压氨泵入口流量低联锁改造

尿素装置高压氨泵原来的入口流量低联锁能够满足在吸入流量低的时候打开回流阀确保泵的安全,但是无法满足泵启动过程等特殊情况下的操作需求,论述如何从软件、硬件两个方面进行联锁改造。     

材料化学双语教学的定位与实践思考

本文通过中美材料化学教材结构分析、生物质材料的界定,探讨了材料化学双语教学的定位;在材料化学双语教学实践中,探讨了教材的选取,明确了讲授内容,并适当增加了先进材料制备和表征技术应用于生物质材料的内容;总结了双语教学网络辅助教学平台的建设和双语教学实践模式的有益探索以及目前存在的问题。     

Change in soil available phosphorus in relation to the phosphorus budget in China

Limited information on soil available phosphorous (P) status has restricted rational P-management strategies, which are necessary to develop, budget, and control P fertilizer inputs. This study was conducted to quantify the relationship between the P budget (P input minus output) and soil available P content (Olsen-P) and its variation from seven long-term experiments that covered subtropical and temperate zones with seven crop systems and six soil types. Across all years and experiments, soil available P content increased linearly with increasing P budget (P?<?0.01), and the increase in soil available P content in the 0?C20 cm topsoil layer by each 100?kg P budget was 1.44?C5.74?mg kg^?1 for the seven sites. This large variation can be explained by the different environments, crop systems, and soil physico-chemical properties. These results will help to predict long-term changes in soil available P using the annual P budget and provide useful information for proper management of P fertilizer.