硅烷偶联剂对表面微坑复合PTFE的减摩及缓释性能影响研究

目的探究硅烷偶联剂对缸套表面微坑复合PTFE微粒的减摩和缓释性能的影响。方法利用激光刻蚀机在缸套表面加工不同参数的微坑,并依据摩擦系数对表面微坑参数进行优化。选取最佳表面微坑参数,进行加工,并机械涂覆经硅烷偶联剂修饰的PTFE,制备复合润滑结构。采取往复式摩擦磨损试验机对复合润滑结构的减摩性能进行分析。利用SEM和EDS研究摩擦副的表面形貌和成分,采用三维共聚焦显微镜研究微坑内PTFE的释放情况。结果在热压复合方法下,直径为0.4 mm、深度为120μm的微坑复合PTFE具有最佳的减摩效果。硅烷偶联剂的加入会进一步改善摩擦副之间的减摩性能,其摩擦系数为0.1248。与未处理缸套试样、微坑处理缸套试样、热压复合PTFE缸套试样进行对比,其摩擦系数分别降低了24.3%、18.8%和11.2%。另外,硅烷偶联剂还可以减缓表面微坑内PTFE的释放,延长作用时效,与热压复合方法相比,微坑内PTFE颗粒的释放速率约降低96.3%。结论复合润滑结构能够改善摩擦副之间的摩擦状况,其减摩和缓释机理是固体自润滑材料、表面微坑和硅烷偶联剂协同作用的结果。     

SBA-15固载磷钨酸催化剂的制备及催化合成叔丁基苯酚

以不同硅烷偶联剂改性的介孔分子筛SBA-15为载体、PW_(12)为催化剂,通过对SBA-15表面共价及非共价修饰制备磷钨酸@介孔分子筛/硅烷偶联剂复合催化剂PW_(12)@SBA-15/YSiX_3(YSiX_3=Apts、Atapts、Papts);并利用FT-IR、XRD、TEM、N_2吸附-脱附对其组成、结构及形貌进行表征。以改性SBA-15分子筛固载磷钨酸催化剂催化合成叔丁基苯酚为研究对象,考察不同硅烷偶联剂、反应温度、苯酚与叔丁醇物质的量比对催化合成叔丁基苯酚的影响,并获得合成叔丁基苯酚的最佳工艺条件,即反应温度145℃、n(苯酚)∶n(叔丁醇)=1∶2.5、重时空速2.2 h~(-1),该最佳反应条件下,PW_(12)@SBA-15/Apts催化剂催化合成叔丁基苯酚的催化活性最高,苯酚转化率为98.3%,2,4-二叔丁基苯酚选择性为57.3%.     

聚合釜粘釜的主要原因及预防措施

分析了105 m^3聚合釜PVC生产过程中影响聚合釜粘釜的主要因素,并提出了相应措施。     

抗硫化返原剂PK900在全地形轮胎胎面胶中的应用

研究抗硫化返原剂PK900在全地形轮胎胎面胶中的应用。结果表明:在全地形轮胎胎面胶中添加抗硫化返原剂PK900,胶料硫化速度变化不大,抗硫化返原性能提高,在过硫条件下硫化胶可保持较好的物理性能;成品轮胎的耐久性能提高,使用寿命延长。     

Thermal effects in H2O and CO2 assisted direct carbon solid oxide fuel cells

Thermal effects in a H₂O and CO₂ assisted tubular direct carbon solid oxide fuel cell (DC-SOFC) are numerically investigated. Parametric simulations are further conducted to study the effects of operating potential, the distance between carbon and anode, inlet gas temperature, and anode inlet gas flow rate on the thermal behaviors of the fuel cell. It is found that the fuel cell with H₂O as gasification agent performs considerably better than the cell with CO₂ as gasification agent in all cases. It is also found that the temperature field of the fuel cell is highly uneven. The breakdown of the heat sources in the fuel cell shows that the H₂O assisted DC-SOFC has much higher heat generation and consumption than the CO₂ assisted cell. Interestingly, a thermal neutral voltage is observed, at which no heating or cooling of the cell is needed. In addition, the distance between the anode and the carbon layer is required to be as small as possible, which improves the temperature uniformity of the fuel cell. The results of this study demonstrates the importance of thermal effects in DC-SOFCs and form a solid foundation for DC-SOFC thermal management.     

Fabrication and characterization of MnO2 based composite sheets for development of flexible energy storage electrodes

Development of cost efficient, flexible and light weight paper electrodes for high-tech applications is high in demand in era of modern disposable technology. In this study α-MnO₂ nanorods were fabricated through hydrothermal method by varying growth time and further combined with lignocelluloses fibers extracted from self growing plant, Monochoria Vaginalis. Crystal structure, morphology and thermal properties of MnO₂ nanorods were characterized by X. Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Thermogravimetric Analysis (TGA), respectively. FESEM image analysis revealed the highest aspect ratio of 48.016 for 4?h treated MnO₂ sample and high purity level was confirmed by XRD. MnO₂ sample with high aspect ratio, relatively pure and larger yield was selected for incorporation of lignocelluloses fibers to fabricate flexible, light-weight and environmentally safe LC/MnO₂ composite paper sheet. Furthermore, LC/MnO₂ composite sheet was employed as working electrode in 2?M sodium sulfate electrolyte for cyclic voltammetry measurements. Presented LC/MnO₂ composite sheet revealed specific capacitances 117, 59, 39, 25 and 23?F/g at scan rates of 5, 10, 20, 50 and 100?mV/s, respectively. Incorporation of LC fibers within MnO₂ nanorods as binders will open the possibilities to fabricate the flexible paper electrode for application in supercapacitors and batteries due to facile synthesis, light-weight and environmentally friendly aspects.     

Synthesis of ZnO rod arrays on aluminum recyclable paper and effect of the rod size on power density of eco-friendly nanogenerators

In this work, we demonstrated a novel and effective approach on the use of low-cost electrodes, an eco-friendly substrate and zinc oxide (ZnO) micro or nanorods (MRs or NRs, respectively) for building triboelectric devices (TENGs). The reported strategy focuses on using low-cost materials and fabrication processes. For the first time and without any pre-treatment, an aluminum recyclable paper from the milk carton (named ARP) was used as a substrate and TENG bottom electrode. A systematic study on the growing of ZnO structures on ARP by chemical bath deposition has been carried out. We found that the ZnO rods size, and resistivity of the TENG upper electrode considerably influence the power density of the device. Such sustainable, low-priced ZnO-based TENGs can produce up to 1.6μW/cm² output power density when operated at 50?Hz. The fabrication of an eco-friendly nanogenerator demonstrates the possibility of manufacturing low-cost, flexible, and large-area energy harvesting devices for future applications.     

Improved oxidation resistance of expanded graphite through nano SiC coating

Expanded graphite with nano SiC and amorphous SiC_xO_y coating was successfully prepared through pyrolysing silane coupling agent (SCA), where the grafting of SCA dominated the final products. The results show that mainly amorphous SiC_xO_y coating covers expanded graphite at 1000 °C, regardless of the SCA concentration. In comparison, nano SiC coating can be synthesized at 1200 °C depending on the good dispersion of SCA (with a SCA concentration of 50 vol%). The formed SiC coating contributes to much higher peak oxidation temperature (812.1 °C) than 678.0 °C of the pure expanded graphite. Meanwhile, the oxidation activation energies of expanded graphite are remarkably improved from 149.15 kJ/mol to 176.16 kJ/mol (based on Kissinger method), attributing to the derived nano SiC and SiC_xO_y coating.