大圆坯环形锻件探伤缺陷类型及机理论述

为了揭示大圆坯锻件环形探伤不合格的原因,结合研究情况论述了多种不同类型缺陷形态及构成,并分析了各类型缺陷的宏观及微观特征、提出产生缺陷的原因以及解决措施。大圆坯锻件探伤不合格的主要原因有夹渣、内部裂纹以及应力裂纹3种形式,防止产生探伤不合格的主要工艺措施有防止产生二次氧化渣、结晶器卷渣以及水口堵塞、保证连铸在冷却过程的均匀冷却,降低钢中氧含量,并且避免产生应力集中的加工方式等。     

改性等规聚丙烯的熔体形态和晶形变异研究

采用凝胶渗透色谱（ＧＰＣ）、光学偏光显微镜、光学解偏仪、差热扫描量热法（ＤＳＣ）、热重分析（ＴＧＡ）等方法,研究了等规聚丙烯（ＩＰＰ）经化学降解后的相对分子质量、相对分子质量分布、结晶形态与热性能的变化。讨论了改进剂使ＩＰＰ相对分子质量分布变窄的机理,分析了熔体在相对静止状态及受力流动时分子运动的影响因素。发现ＩＰＰ经化学降解后存在β晶型的织构     

锆英石水口异常侵蚀的机理

通过对侵蚀后的锆英石水口砖的岩相分析及矿相的微区分析,探讨了侵蚀前后的矿相变化及侵蚀原因     

Modelling of granulation by a two-stage auto-layering mechanism in continuous industrial drums

A mechanistic model for the granulation of particulate materials with a wide size distribution in a large-scale continuous drum is presented. It takes cognizance of the effect of relevant process variables: feed size distribution, moisture content, binders such as lime, residence time distribution, feed rate, etc. The model is based on the auto-layering mechanism of granule growth and incorporates a piecewise linear model for granulation kinetics. Laboratory scale tests on a batch drum are used to provide kinetic parameters. The size-dependent residence time distribution of agglomerating mass in the continuous drum is represented by a combination of mixed and plug flow regimes operating in parallel. The model is customized for a continuous drum in an iron ore fines sintering plant. The predicted granule size distributions are in good agreement with the plant data under widely varying operating conditions. The modelling framework provides scope for modifying the individual modules for drum residence time distribution or the granulation mechanism and growth kinetics.     

CN+HCNO反应机理理论计算

我们计算了CN+HCNO反应的反应势能面,使用的方法为QCISD(T)/6-311g(d,p)//UB3LYP/6-31g(d,p)。在计算中我们发现了31个异构体,40个过渡态。为了进一步考虑电子相关我们在QCISD(T)/6-311g(d,p)水平上做了单点能量计算。在改革中可能的初始连接方式中,我们发现进攻碳原子形成异构体b1和b2是最可行的连接方式,主要是因为这是一个无势垒的过程。通过热力学和动力学分析,我们确定通道P4(NCO+HCN)和P2(N2O+HCCO)应该是最可几产物。     

聚氯乙烯树脂热稳定性探讨

通过对聚氯乙烯降解机理的分析,提出在聚合体系中添加助剂并控制单体质量,改进工艺措施,提高PVC树脂制品的热稳定性。     

Preparation of hierarchical WO3 dendrites and their applications in NO2 sensing

Hierarchical WO₃ dendrites were synthesized via low-cost and environmental-friendly solvothermal strategy. Characterization results indicated that WO₃ dendrites were composed of several multi-directional dendritic nanosheets. To further understand the formation of WO₃ dendrites, time-dependent experiments were carried out and formation mechanism was investigated. Since such dendritic structures rarely occurred in the field of gas sensing, the synthesized WO₃ dendrites were subjected to detailed NO₂ sensing tests. Results demonstrated that WO₃ dendrites based sensors had low detection limit (200 ppb) and fast response and recovery (7 s, 12 s to 5 ppm NO₂). Moreover, the sensor was also highly sensitive, selective and stable at low optimal operating temperature of 140 °C.     

固态配料和硝酸盐共沉淀配料制备Bi(Pb)—Sr—Ca—Cu—O系高温超导相的工艺比较

用固态配料和硝酸盐共沉淀配料制备了各组份为(Bi_(1.85)Pb_(0.40))Sr_(1.95)Ca_(2.05)Cu_(8.10)的超导材料,研究了两种不同制备工艺对Bi系超导相形成过程、超导电磁性能和显微结构的影响.实验发现,由共沉淀制备的样品T_(c(zero))稳定性好,T_(c(zero))均在107.5K以上.SEM观察表明:共沉淀法制备的样品中超导相颗粒比固态配料制备的要细小、均匀,颗粒间连结紧密,与T_(c(zero))结果相符.但XRD相分析结果显示:固态配料样品中高温相含量高于共沉淀配料,共沉淀配料制备作品中高、低温相同时存在,但其交流磁化率—温度曲线上仅在120K附近出现相应于高温相的抗磁信号.研究认为,这是由于共沉淀配料烧成时,高温相容易在部分液相参与下,在低温相表面通过反应成核生长,导致在形成的高温相内部包裹有残余低温相的“内芯”.依此包裹模型可自洽地解释X射线相分析与电、磁性能测定结果间的矛盾,讨论了Bi系高温相的形成机理,为选择合理的制备工艺提供了依据.     

新型含氮环氧树脂研究进展

氮系阻燃剂具有高效、低毒(包括其分解产物)等优点,故已成为当今阻燃剂的发展方向。综述了氮系阻燃剂的特点及其阻燃机理,以及目前国内外对含氮环氧树脂(EP)和含氮阻燃固化剂的最新研究进展,并对其发展前景作了展望。