Low Dielectric Polyimide/Fluorinated Ethylene Propylene (PI/FEP) Nanocomposite Film for High-Frequency Flexible Circuit Board Application

The low dielectric polymer films have drawn great attention to the application as the dielectric insulating materials in high-frequency circuit boards, while the weak adhesion to the copper foils and the poor processability resulted from the fluorinated or rigid structures limited their high-frequency application. In this work, the low dielectric and high adhesive polyimide/fluorinated ethylene propylene (PI/FEP) nanocomposite film for high-frequency flexible circuit board application is developed. It is indicated that the fluorocarbon surfactants can significantly improve the dispersion of FEP in PI substrate, and thus, the PI/FEP nanocomposite film exhibits excellent mechanical properties, including the tensile strength increases to 46.6 MPa and the elongation at the break increases to 13.7%. Importantly, at the high-frequency of 10 GHz, the 60 wt% FEP filled PI nanocomposite film displays an ultralow dielectric loss (0.006) and a reduced dielectric constant (2.69). In addition, the high-frequency flexible circuit board with the PI/FEP film as the dielectric insulating layer has a high peel strength of 0.75 N mm⁻¹, indicating this PI/FEP nanocomposite film can meet the requirements of the high-frequency flexible circuit board application.     

3D Printing Conductive Composites with Poly(ionic liquid) as a Noncovalent Intermedia to Fabricate Carbon Circuits

In this study, a kind of imidazole type poly(ionic liquid) ([PEP-MIM]Cl) is synthesized, which can disperse carbon effectively. [PEP-MIM]Cl is used as an intermediate to coat carbon on the poly(acrylic acid)(PAA-co-MBA) via ion exchange to obtain conductive polymer composite (CPC). A series of characterizations are performed. Experiments show that carbon can be coated on the PAA-co-MBA uniformly, and compared with using carbon as filler, this method requires less carbon to achieve good conductive performance. The carbon layer on the polymer's surface is enriched via the swelling-shrinking properties of PAA-co-MBA according to the SEM images. Furthermore, in combination with 3D printing technology, PAA-co-MBA can be designed into different shapes to achieve various functions such as pressure-sensing element. Finally, a new type of CPC named carbon clad polymeric laminate (CCPL) is prepared by using the carbon coating method and 3D printing technology. It has the potential to replace copper clad laminate (CCL) and printed circuit board (PCB), to a certain extent. This technology expands the preparation method and application of the CPC such as flexible and wearable conductive fabrics.     

粉煤灰高附加值利用研究进展

粉煤灰是火电厂燃煤过程中产生的固体残渣, 其成分复杂, 具有毒性, 若处理不当会对环境造成危害。因此, 粉煤灰的高附加值利用迫在眉睫。然而, 粉煤灰的品质是制约其高附加值利用的主要因素。目前, 中国粉煤灰品质参差不齐, 缺少完善的品质评价体系, 由此造成粉煤灰利用领域的局限性。针对上述问题, 首先分析了中国粉煤灰的资源化特性, 总结了粉煤灰的品质评价方法, 并重点阐述了适用于粉煤灰高附加值利用的品质评价方法;其次, 详细介绍了粉煤灰高附加值利用技术（高附加值提取技术、高附加值材料制备技术）;最后, 对粉煤灰高附加值利用的发展趋势做出了展望。     

岩溶区石灰石矿山溶洞探测分析

江西南城南方水泥有限公司蒋源矿区矿山开采过程中发现了溶洞,并利用空洞仪（一种物探设备）对溶洞探测并采集数据以及使用RTK对溶洞分布情况进行坐标数据采集。经过对空洞仪成像分析,结合现场采集的数据制作出溶洞空间分布图,精确掌握溶洞发育的规模、空间状态,对制定岩溶发育区域矿山开采、爆破施工方案、应急预案,以及确保施工安全起到了非常重要的作用。     

Effects of Ultrasonic Vibration on Material Flow and Thermal Cycles in Friction Stir Welding of Dissimilar Al/Mg Alloys

Comparative experiments are performed in friction stir welding (FSW) of dissimilar Al/Mg alloys with and without assistance of ultrasonic vibration. Metallographic characterization of the welds at transverse cross sections reveals that ultrasonic vibration induces differences in plastic material flow in two conditions. In FSW, the plastic material in the peripheral area of shoulder-affected zone (SAZ) tends to flow downward because of the weakening of the driving force of the shoulder, and a plastic material insulation layer is formed at the SAZ edge. When ultrasonic vibration is exerted, the stirred zone is divided into the inner and outer shear layers, the downward material flow trend of the inner shear layer disappears and tends to flow upward, and the onion-ring structure caused by the swirl motion is avoided in the pin-affected zone. By improving the flow behavior of plastic materials in the stirred zone, ultrasonic vibration reduces the heat generation, accelerates the heat dissipation in nugget zone and changes the thermal cycles, thus inhibiting the formation of intermetallic compound layers.

     

Preparation of ceramic coatings on inner surface of steel tubes using a combined technique of hot-dipping and plasma electrolytic oxidation

A new method for inner surface modification of steel tubes, named a combined technique of hot-dipping and plasma electrolytic oxidation (PEO) was proposed and demonstrated in this paper. In this work, metallurgically bonded ceramic coatings on inner surface of steel tubes were obtained using this method. In the combined process, aluminum coatings on steel were firstly prepared by the hot-dip process and then metallurgically bonded ceramic coatings were obtained on the aluminum coatings by PEO. The element distribution, phase composition and morphology of the aluminide layer and the ceramic coatings were characterized by SEM/EDX and XRD. The corrosion resistance of the ceramic coatings were also studied. The results show that, after hot-dip treatment, the coating layers consist of two layers, where Al, Fe_xAl _(1−x) were detected from external topcoat to the aluminide/steel substrate. Then after PEO process, uniform Al₂O₃ ceramic coatings have been deposited on inner surface of steel tubes. The ceramic coatings are mainly composed of -Al₂O₃ and γ-Al₂O₃ phase. The compound coatings show favorable corrosion resistance property. The investigations indicate that the combination of hot-dipping and plasma electrolytic oxidation proves a promising technique for inner surface modification of steel tubes for protective purposes.     

SBTV铁电材料的制备和微观组织结构

采用固相反应法合成了SrBi2Ta2O9(简称SBT)和V掺杂SrBi2Ta2O9(简称SBTV)陶瓷,通过TG-DTA、XRD、SEM、TEM等技术手段研究了材料的烧结工艺、相组成和微观组织结构.研究表明V2O5是一种很好的助烧剂,掺杂后材料的烧结温度可降低200℃烧结后纯SBT均为单一的钙钛矿相SBT;掺杂后2种成型工艺所制备的SBTV除了生成少量Bi4(V2O11)外,仍主要由钙钛矿相组成;同时所有的材料都发生了一定程度的择优取向.掺杂后材料的晶粒形态发生变化棒状转化为片状.同时V掺杂后引起了晶格畸变,产生应变,SBTV材料在透射中观察到具有α-边界特征的90°畴.     

Effect of temperature on anodic behavior of 13Cr martensitic steel in CO2 environment

The corrosion behavior of 13Cr martensitic stainless steel in a CO₂ environment in a stimulated oilfield was studied with potentiodynamic polarization and the impedance spectra technique. The results showed that the microstructure of the surface scale clearly changed with temperature. This decreased the sensitivity of pitting corrosion and increased the tendency toward general (or uniform) corrosion. The capacitance, the charge transfer resistance, and the polarization resistance of the corrosion product scale decrease with increasing temperature from 90 to 120 °C, and thus the corrosion is a thermal activation controlled process. Charge transfer through the scale is difficult and the corrosion is controlled by a diffusion process at a temperature of 150 °C. Resistance charge transfer through the corrosion product layer is higher than that in the passive film.     

Study on Tribological Properties of Polytetrafluoroethylene Drawn Uniaxially at Different Temperature

Summary: Wear behavior correlations with morphology have been established from polytetrafluoroethylene (PTFE) drawn at 200, 327, and 375 °C with draw ratio about 4. The friction coefficient and wear rate for PTFE drawn at 327 °C are lower and the wear rate is lower than that of undrawn PTFE by about 30%. The structures of samples were characterized by scanning electron microscope (SEM), DSC, and wide angle X‐ray diffraction (WAXD). Results indicate that the debris morphologies of samples are different. The differences in the tribological behavior of undrawn and drawn samples were attributed to the improvement of the degree of the crystalline, fibrillation, and orderliness by drawing, especially, for PTFE drawn at 327 °C. The orderliness of molecular arrangement along the drawn direction is also higher for PTFE drawn at 327 °C than those of PTFE drawn at 200 and 375 °C, respectively. Therefore, the intensity of covalent bond along drawn direction is higher. The shear resistance and the deformability of the material are greatly improved and the size of the wear breakage unit decreases, which results in a good tribological property for PTFE drawn at 327 °C.

SEM morphology of fractured surface perpendicular to the draw direction for PTFE drawn at 327 °C.     

单组分阴离子水性聚氨酯胶膜的热质研究

应用热质分析（TG）研究了单组分阴离子水性聚氨酯胶膜的耐热性能，结果表明：n（--NCO）：n（--OH）增大，胶膜的耐热性能增强；聚酯相对分子质量增加，耐高温性能降低；用DEG扩链时的耐高温性能比用DEG／TMP时的好；TDI型水性聚氨酯成膜物的耐高温性能优于IPDI型水性聚氨酯。