水溶性聚丙烯酸类高效减水剂的合成及表征

以丙烯酸、丙烯酸甲酯、甲基丙烯酸、顺丁烯二酸酐、烯丙基磺酸钠单体为原料,自由基共聚合成了不同单体组合和配比、不同分子量的不同结构类型的丙烯酸类系列减水剂。通过红外光谱法对共聚物的组成进行了表征,分别采用黏度法和电泳法等方法测试了系列聚合物的特性黏数、减水剂水溶液的表面张力、掺减水剂水泥浆体的ζ电位和掺减水剂的水泥净浆流动度。结果显示,系列丙烯酸类聚合物均具有一定的表面活性,能使水泥浆体ζ电位的绝对值增大;减水剂的链结构、分子量、羧酸根负离子的数量及其分布及基团的空间位阻大小等都对减水性能产生影响。     

Plasma Modification of Activated Carbon Fibers for Adsorption of SO_2

Viscose-based activated carbon fibers(VACFs)were treated by a dielectric-barrier discharge plasma under the feed gas of N_2.The surface functional groups of VACFs were modified to improve the adsorption and catalysis capacity for SO_2.The surface properties of the untreated and plasma-treated VACFs were diagnosed by SEM,BET,FTIR,and XPS,and the adsorption capacities of VACFs for SO_2 were also compared and discussed.The results show that after the plasma treatment,the external surface of VACFs was etched and became rougher,while the surface area and the total pore volume decreased.FTIR and XPS revealed that nitrogen atoms were introduced onto the VACFs surface and the distribution of functional groups on the VACFs surface was changed remarkably.The adsorption characteristic of SO_2 indicates that the plasmatreated VACFs have better adsorption capacity than the original VACFs due to the nitrogen functional groups and new functional groups formed in modification,which is beneficial to the adsorption of SO_2.     

板坯连铸结晶器冷却铜板的温度场分析及结构优化

采用结构分析有限元软件ABAQUS对具有不同冷却系统的两种结晶器在工作过程中的稳态温度场进行了模拟。在所采用的热材料参数和边界条件尽町能符合实际条件下。证明了采用新的设计可获得较理想的温度场分布。其结果对连铸结晶器的设计及优化、提高结晶器寿命和改善板坯质量具有指导作用。     

船用柴油机供油机构滚轮衬套混合热弹流润滑特性研究

以船用柴油机供油机构中滚轮–浮动衬套–滚轮销为研究对象,考虑其低速重载运行工况下衬套弹性变形,计入表面粗糙特征,构建了浮动衬套内外双层油膜混合热弹性流体动压润滑分析模型,并据此探究了内外层油膜间隙比、衬套宽径比、衬套厚度及其表面粗糙度对环速比、内外层最大油膜压力及承载能力等润滑特性的影响规律。结果表明：滚轮–浮动衬套–滚轮销结构运行过程中内层油膜厚度较小,润滑状态较为恶劣;低速重载工况下,衬套弹性变形与混合润滑效应不可忽略;宽径比越大、内外层间隙比越小,最大油膜压力越小,结构承载能力越强,但温升越高;混合润滑状态仅出现于衬套内层润滑油膜,且衬套表面粗糙度越大,润滑效果越差。     

板坯连铸过程包含相变的三维瞬态热传导数值模拟

利用有限元软件ABAQUS／Standard对连铸结晶器和板坯进行了三维瞬态热传导数值分析，数值模拟计算了温度场．假设相变是在恒温下进行的，三维瞬态热传导方程中引入了潜热，即模拟过程考虑了金属结晶过程中释放的热量．同时也考虑了运动的板坯与结晶器之间的相互作用，从而获得了更准确的连铸过程中结晶器和板坯的温度场分布．     

板坯连铸过程包含相变的三维瞬态热传导数值模拟

利用有限元软件ABAQUS/Standard对连铸结晶器和板坯进行了三维瞬态热传导数值分析,数值模拟计算了温度场.假设相变是在恒温下进行的,三维瞬态热传导方程中引入了潜热,即模拟过程考虑了金属结晶过程中释放的热量.同时也考虑了运动的板坯与结晶器之间的相互作用,从而获得了更准确的连铸过程中结晶器和板坯的温度场分布.