助熔剂和密着剂对搪玻璃的作用机理及其研究进展

搪玻璃是一种在金属表面喷涂瓷釉(搪玻璃釉),经高温搪烧密着而成的复合材料,既具有玻璃的化学稳定性,又具有金属材料的硬度大、强度高等优良特性,同时表面光滑易清洗,因此在化工、医药等行业广泛应用。搪玻璃性能取决于搪玻璃釉的成分,搪玻璃釉包括基体剂、乳浊剂、助熔剂、密着剂等,其中助熔剂中含有低熔点物质,能够降低熔化温度,破坏搪玻璃釉连续的网络结构,形成新分子键,进而改良搪烧工艺;密着剂能够与金属基体发生化学反应,增强搪玻璃釉和金属基体的结合强度,进而提高力学性能。本文简要介绍了搪玻璃釉中的各类助剂,着重叙述了助熔剂和密着剂的组成及作用机理,为今后设计搪玻璃釉及提高搪玻璃设备性能提供了参考依据。     

等离子熔覆技术的研究进展

等离子熔覆技术是一种有效且实用的表面处理技术,具有熔覆层与基体结合强度高,涂层组织均匀细小,综合性能良好,成本低等优点。从熔覆层材料、工艺参数对熔覆层的影响、新型等离子熔覆技术等几方面综述了等离子熔覆技术的研究进展,同时也指出了等离子熔覆技术现存的问题以及未来的主要研究方向。     

Promising approaches to improve the performances of hybrid non‐isocyanate polyurethane

The performances of hybrid non‐isocyanate polyurethane (NIPU) materials were improved by using promising approaches. For the ring‐opening reaction of cyclic carbonate with excess amine, methanol was selected as solvent to increase the molar mass of NH₂‐terminated NIPU pre‐polymer but also caused the formation of urea as a result of eliminating hydrogen bonding between NIPU chains. Meanwhile, another approach was carried out to reduce the content of urea by altering the introduction mode of reactants, along with further increasing the molar mass of the NIPU pre‐polymer. The final hybrid materials were prepared by adding bisphenol‐A diglycidyl ether into the pre‐polymer. The results indicated that the introduction of methanol and the change of the introduction mode of reactants could improve the performance of the hybrid materials. The hybrid material derived from the forward method has optimal performance with a tensile strength of 10.8 MPa, elongation at break of 167%, a glass transition temperature of 49.1 °C and a crosslinking density of 450 mol m^?3 as well as presentable thermodynamic stability, ascribed to the high molar mass of the NIPU pre‐polymer, the low urea content and the dense crosslinking network. © 2018 Society of Chemical Industry     

Graphitic nanorings for super-long lifespan lithium-ion capacitors

Porous graphitic carbon nanorings (PGCNs) are proposed by smart catalytic graphitization of nano-sized graphene quantum dots (GQDs). The as-prepared PGCNs show unique ring-like morphology with diameter around 10 nm, and demonstrate extraordinary mesoporous structure, controllable graphitization degree and highly defective nature. The mechanism from GQDs to PGCNs is proven to be a dissolution-precipitation process, undergoing the procedure of amorphous carbon, intermediate phase, graphitic carbon nanorings and graphitic carbon nanosheets. Further, the relationship between particles size of GQDs precursor and graphitization degree of PGCNs products is revealed. The unique microstructure implies PGCNs a broad prospect for energy storage application. When applied as negative electrode materials in dual-carbon lithium-ion capacitors, high energy density (77.6 Wh·kg⁻¹) and super long lifespan (89.5% retention after 40,000 cycles at 5.0 A·g⁻¹) are obtained. The energy density still maintains at 24.5 Wh·kg⁻¹ even at the power density of 14.1 kW·kg⁻¹, demonstrating excellent rate capability. The distinct microstructure of PGCNs together with the strategy for catalytic conversion from nanocarbon precursors to carbon nanorings opens a new window for carbon materials in electrochemical energy storage.

     

玻璃化深低温保存小鼠卵巢组织的研究

对小鼠卵巢组织进行玻璃化深低温保存的初步研究,探索合适的玻璃化保护剂及保存方法。取3周龄小鼠卵巢组织,采用不同保护剂进行玻璃化深低温保存,-196℃液氮保存一周后复温,进行组织切片HE染色观察,筛选合适的玻璃化保护剂;对保存后的小鼠卵巢组织进行自体移植体内培养2周后,取出卵巢组织进行形态学观察及基因表达研究,采用RT-PCR方法检测到了在原始卵泡向初级卵泡发育过程中特异表达的AMH基因及在各个阶段的卵泡中均表达的KL基因。结果表明采用高浓度渗透性保护剂（二甲基亚砜、乙酰胺、丙二醇）的玻璃化保护液对小鼠卵巢组织保存效果较好,说明采用玻璃化技术保存卵巢组织的方法可行,并可采用检测基因表达的方法验证深低温保存卵巢组织的效果。     

一种滤除内燃机曲轴瞬时转速信号畸点的方法

在周期性的内燃机曲轴瞬时转速实测信号中常会出现许多畸点。为滤除畸点,一般采用低通滤波的方法,但低通滤波法有其局限和不足之处,为此,提出了一种快速衰减畸点值而不会带来其他误差的方法。     

基于DEFORM的柴油机连杆粉末锻造模具优化

粉末锻造质量的评价标准之一是粉末锻造件的成形密度。为了提高粉末锻造件的致密度,有必要研究模具结构和工艺参数对粉末锻造件致密度的影响。以某煤矿用柴油机连杆件的粉末锻造为例,研究了不同锻造工艺参数下的粉末锻造连杆的致密度分布规律和对连杆内部变形抗力的影响规律,并据此提出了双向压缩方式的锻造模具结构,实现了锻件密度上升和最大应力降低。     

Electrospinning-Enabled Si/C Nanofibers with Dual Modification as Anode Materials for High-Performance Lithium-Ion Batteries

In this work,silicon@reduced graphene oxide/pyrolytic carbon nanofibers(Si@RGO/C NFs) composite with double modified layer is prepared through electrospinning,stabilization and carbonization.In this composite,polyethylene oxide-polypropylene oxide-polyethylene oxide(P123,a non-ionic surfactant) is introduced as the dispersant,which can make silicon nanoparticles evenly dispersed in electrospinning solution to prevent it from agglomeration.Graphene modified layer can buffer the volumetric expansion of silicon nanoparticles,prevent direct contact between silicon and electrolyte as well as enhance the electrical conductivity.Moreover,carbon fibers synthesized by electrospinning can encapsulate silicon@graphene composite internally to form a double modified layer.This composite with double modified layer can further alleviate the volume change of silicon nanoparticles and avoid direct contact between silicon and electrolyte to form a stable interface.Owing to the above-mentioned merits,the Si@RGO/C NFs composite exhibits excellent cyclic stability and superior rate performance.Particularly,it maintains a specific capacity of 929 mA h g~(-1) with the retention ratio of 83.1% after 100 cycles at 0.5 A g~(-1) and delivers an outstanding rate capability of 1003 mA h g~(-1) at 2 A g~(-1).     

氢回收装置缠绕管式换热器设计计算研究

研究了合成氨氢回收装置缠绕管式换热器的热力设计计算方法 ,探讨了换热器中并管传热模型、含氢多组分混合物汽液平衡、物性参数以及冷凝和蒸发等传热计算问题。提出的方法可用于工程设计计算