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991.
992.
盐石膏的主要成分为无水硫酸钙,其活性差、凝结硬化慢、强度低,需要添加活性剂来激发盐石膏的活性。通过复合外加剂对盐石膏加以改性,并通过XRD和SEM对其作用机理做了分析。结果表明,单掺脱硫石膏和建筑石膏均能缩短盐石膏的凝结时间,建筑石膏的效果较好,但掺量不宜过高。复掺建筑石膏和缓凝剂时,两者比例要控制得当,适宜的建筑石膏和缓凝剂掺量分别为50%和0.10%~0.12%(质量分数)。分析可知,大掺量建筑石膏会增加盐石膏硬化体中二水相和针棒状晶体的含量;缓凝剂掺量的增加,会降低盐石膏硬化体中二水相的含量,棱形晶体增多,从而降低了盐石膏的强度。 相似文献
993.
为了缓解硅基负极材料的体积膨胀并改善其电化学性能,以Mg、SiO和石墨为原料,成功制备出一种多相Si-MgO-G复合材料。探讨了不同高能球磨工艺对Mg和SiO反应程度的影响及厚膜成型技术的应用。结果表明,当高能球磨(1+5)h后,Mg和SiO原位反应生成Si-MgO产物,将反应产物与石墨混磨制备成多相Si-MgO-G复合材料。用XRD、SEM 和TEM等手段对制得材料的结构、形貌和成分进行分析,证实了复合材料是由Si、MgO和石墨组成,其中Si(220)//MgO(200)之间存在晶面共格关系。用CV和EIS等对捏合开炼厚膜技术制得负极极片进行电化学性能分析,结果表明,捏合开炼工艺制备的厚膜极片的厚度、载量和面积比容量分别约为薄膜极片的7.4倍、6.0倍和6.2倍。采用简单、绿色和可规模化生产的厚电极制备技术,可提高锂离子电池的面积比容量。 相似文献
994.
Priyanka Kamble Prithwish Sinha Roy Arvind Ananthanarayanan Jayesh G Shah Gopalakrishnan Sugilal 《分离科学与技术》2020,55(9):1603-1610
ABSTRACTA new composite of crystalline silicotitanate (CST) has been synthesized for the sequestration of Cs and Sr from low-level liquid waste generated in the nuclear industry. The product characterization using X-RAY DEFRACTION (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of CST crystals in the composite. Sorption studies carried out under various test conditions showed that the composite has high affinity for both Cs and Sr. Results of structural characterization of Cs and Sr-loaded CST indicated that the overall structural integrity remained intact after substitution of Na+ by Cs+ or Sr2+. The exceedingly good Cs and Sr sorption performance displayed by the CST composite will find applications in the treatment of nuclear waste. 相似文献
995.
Ying Liu Yunlong Ai Wen He Weihua Chen Jianjun Zhang 《Ceramics International》2018,44(14):16421-16427
The grain growth kinetics and mechanical properties of graphene platelets(GPLs) reinforced ZrO2/Al2O3(ZTA) composites prepared by microwave sintering were investigated. The calculated grain growth kinetics exponent n indicated that the GPLs could accelerate the process of the Al2O3 columnar crystal growth. And the grain growth activation energy of the Al2O3 columnar crystal indicated that the grain growth activation energy of the GPLs doped ZTA composites is much higher than those of pure Al2O3 and ZTA in microwave sintering. The optimal mechanical properties were achieved with 0.4?vol% GPLs, whose relative density, Vickers hardness and fracture toughness were 98.76%, 18.10?GPa and 8.86?MPa?m1/2, respectively. The toughening mechanisms were crack deflection, bridging, branching and pull-out of GPLs. The results suggested that GPLs-doped are good for the Al2O3 columnar crystal growth in the ZTA ceramic and have a potentially improvement for the fracture toughness of the ceramics. 相似文献
996.
Novel microspheres (CPs) composited by rigid and flexible polymers are synthesized and embedded in the supporting membranes to enhance both the skin–substrate adhesion and compaction resistance of the thin‐film composite (TFC) nanofiltration membranes. The CPs are in situ formed in the casting solution after the rigid poly(p‐phenylene terephthamide) (PPTA) is produced in the flexible poly(m‐phenylene isophthalamide) (PMIA) solution. Then the PPTA/PMIA in situ blending membranes are prepared by using the NIPs method, and the TFC NF membranes are fabricated via interfacial polymerization on them. The CPs are characterized via polarizing microscopy and TEM. The surface morphology and chemical composition of the blended membranes are characterized by using FESEM, AFM, FTIR, and WCA, respectively. As the results show, the supporting membrane with higher PPTA content exhibits higher permeability, thermal stability, and compaction resistance. Moreover, the adhesion strength between the TFC functional layer and the supporting membrane is improved significantly. It is proposed that this improvement can be attributed to the CPs that are exposed on the top surface of the supporting membrane, which leads to a great enhancement because of the anchoring effect between the functional layer and the CPs. 相似文献
997.
Donghai Ding Lihua Lv Guoqing Xiao Jiyuan Luo Changkun Lei Yun Ren Shoulei Yang Pan Yang Xing Hou 《International Journal of Applied Ceramic Technology》2020,17(2):645-656
The paper investigated the effects of different amounts (0%, 3%, 6%, 9%) of in situ multilayer graphene/MgAl2O4 composite powders on the slag resistance, thermal shock resistance, and oxidation resistance of low-carbon MgO-C refractories. Comparing with commercial MgAl2O4, the MgAl2O4 in in situ multilayer graphene/MgAl2O4 composite powders has higher lattice strain of crystal, which can trap more Mn and Fe ions, resulting in the better slag resistance. The oxidation decarbonation layer of MgO-C specimen with 3% composite powders is 9.71 mm, which is lower than not only the specimen with other contents but also specimen containing carbon black/MgAl2O4 powders. Moreover, the residual strength ratio of the specimen C/MA-3 was 47.47%, which is 28.5% and 8.08% higher than specimens with no additive and with carbon black/MgAl2O4 powders, respectively. Both improving thermal shock and oxidation resistance properties are related with the unique nano structure, multilayer graphene in situ formed between MgAl2O4 grains, of added composite powders. The former is due to higher strain energy consumed by multi-deflection of cracks inside the multilayer graphene/MgAl2O4 composite powders. And the latter is due to the higher energy of oxidation activation of multilayer graphene/MgAl2O4 composite powders due to effective protection of multilayer graphene by MgAl2O4. 相似文献
998.
999.
Flexible pressure sensors have potential applications in human motion monitoring and electronic skins. To satisfy the practical applications, pressure sensors with a high sensitivity, a low detection limit, a broad response range, and an excellent stability are highly needed. Here, a piezoresistive pressure sensor based on wavy‐structured single‐walled carbon nanotube/graphite flake/thermoplastic polyurethane (SWCNT/GF/TPU) composite film is fabricated by a prestretching process. Due to the random wavy structure, high conductivity, and good flexibility, the prepared sensor displays a low detection limit of 2 Pa, a wide sensing range of 0–60 kPa, and a high sensitivity of 5.49 kPa?1 for 0–50 Pa. Furthermore, the sensor shows a remarkable repeatability of over 1.1 × 104, 9.0 × 103, and 2.0 × 103 pressure loading/unloading cycles at 50 Pa, 500 Pa, and 30 kPa, respectively, and a fast responsibility of 100–150 ms of loading response time and 400–600 ms of relaxation time. Therefore, the pressure sensor is successfully adopted to monitor both the large‐scale human activities (e.g., walk and jump) and the small‐scale signals (e.g., wrist pulse). Furthermore, a sensor array is assembled to map the weight and shape of an object, indicating its various potential applications including human–machine interactions, human health monitoring, and other wearable electronics. 相似文献
1000.
采用激光熔覆工艺在TC4钛合金基体表面制备了添加不同质量分数(0%、2%、4%、6%)TiC的Ni60A复合熔覆层,通过光学显微镜、显微硬度计、X射线衍射仪、摩擦磨损机分析了不同TiC含量对熔覆层组织及性能的影响。结果表明:未添加TiC的熔覆层组织以树枝晶为主,添加TiC后出现了花瓣状物相;XRD分析发现熔覆层中出现了AlCCr2、Al0.24B0.01Ni0.75等硬质增强相,这些能够显著提高熔覆层的硬度。显微硬度及摩擦磨损试验结果表明,添加TiC的熔覆层平均硬度均较基体硬度有大幅提高,摩擦因数显著降低,且随TiC含量的增加,熔覆层硬度先增加后降低,摩擦因数先降低后增加,4%TiC熔覆层的硬度最大,相比基体提高了213.3%,摩擦因数最小,为0.309 774。 相似文献