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31.
32.
为解决电镀砂轮磨削加工中容屑空间不足的问题,采用点胶微粘接的方法制备了磨料有序排布的电镀砂轮,分析了磨料粘接效果和镀层力学性能。通过SEM分析了磨料/镀层/导电胶的结合界面,并进行了干磨削试验。研究结果表明,直径约为磨料粒径40%的胶点可粘接住磨料,单个胶点上粘接多颗磨料的占比小于6%;双脉冲电镀工艺制备的镀层显微硬度大于500HV,表层残余应力小于100MPa,磨料/镀层/导电胶之间的界面贴合紧密,无明显缺陷;砂轮在磨削时没有出现磨料脱落现象。 相似文献
33.
Alison Willette Benjamin Fallen Hem Bhandari Carl Sams Feng Chen Virginia Sykes Chris Smallwood Kristin Bilyeu Zenglu Li Vincent Pantalone 《Journal of the American Oil Chemists' Society》2021,98(8):861-869
Soybean oil hydrogenation alters the linolenic acid molecule to prevent the oil from becoming rancid, however, health reports have indicated trans-fat caused by hydrogenation, is not generally regarded as safe. Typical soybeans contain approximately 80 g kg−1 to 120 g kg−1 linolenic acid and 240 g kg−1 of oleic acid. In an effort to accommodate the need for high-quality oil, the United Soybean Board introduced an industry standard for a high oleic acid greater than 750 g kg−1 and linolenic acid less than 30 g kg−1 oil. By combing mutations in the soybean plant at four loci, FAD2-1A and FAD2-1B, oleate desaturase genes and FAD3A and FAD3C, linoleate desaturase genes, and seed oil will not require hydrogenation to prevent oxidation and produce high-quality oil. In 2017 and 2018, a study comparing four near-isogenic lines across multiple Tennessee locations was performed to identify agronomic traits associated with mutations in FAD3A and FAD3C loci, while holding FAD2-1A and FAD2-1B constant in the mutant (high oleic) state. Soybean lines were assessed for yield and oil quality based on mutations at FAD2-1 and FAD3 loci. Variations of wild-type and mutant genotypes were compared at FAD3A and FAD3C loci. Analysis using a generalized linear mixed model in SAS 9.4, indicated no yield drag or other negative agronomic traits associated with the high oleic and low linolenic acid genotype. All four mutations of fad2-1A, fad2-1B, fad3A, and fad3C were determined as necessary to produce a soybean with the new industry standard (>750 g kg−1 oleic and <30 g kg−1 linolenic acid) in a maturity group-IV-Late cultivar for Tennessee growers. 相似文献
34.
《Ceramics International》2022,48(7):9083-9089
Direct-methane solid oxide fuel cells (DMSOFCs) have recently attracted substantial attention due to their simplified system, reduced cost, and the direct availability of methane fuel obtained from natural gas. Among oxygen-ion conductive materials, doped-ceria such as gadolinium-doped ceria (GDC) or samarium-doped ceria can be incorporated into Ni-based anodes to reinforce their coking resistance, enlarge their electrochemical reaction area, and improve the kinetics of the internal reforming/electrochemical oxidation of methane. To reduce the range of operating temperatures of DMSOFCs while maintaining their performance, the thin film deposition technique of magnetron sputtering was adopted in this work. An Ni-GDC thin-film anode and a Pt thin-film cathode were deposited on scandia-stabilized zirconia (ScSZ) electrolyte supports. This fuel cell was tested with directly supplied methane fuel (3% H2O) at 500 °C. The results demonstrated the effects of the GDC volume fraction in the anode—which was controlled by co-sputtering power—on open circuit voltage and electrochemical performance. The co-sputtered Ni-GDC anode was able to survive through 36-h operation, although there was some performance degradation. Field-emission scanning electron microscopy results revealed no formation of filamentous carbon on the Ni catalysts, despite the fact that both X-ray photoelectron spectroscopy and Raman spectroscopy analyses detected carbon coking. The relatively high performance and resistance to carbon coking of co-sputtered thin-film anode were attributed to its intrinsic small grain size. 相似文献
35.
《Ceramics International》2022,48(20):30144-30150
High-capacity and affordable all-solid-state Na-ion batteries have gathered increasing interest in recent years owing to low-cost sodium, which contributes to reducing the price of these Na-ion batteries to approximately 70% of that in lithium batteries. However, in terms of electrolyte performance and battery cost, the complete replacement of lithium batteries has a long way to go. In this work, low-cost and high-safety Na2S·9H2O materials are used in synthesizing Na3SbS4 solid electrolyte, the price of which is only one-fifth that of high-purity Na2S. The structure and electrochemical properties are studied through X-ray diffraction analysis, Raman spectroscopy, scanning electron microscopy, and electrochemical tests. Results indicate that a multiphase Na3SbS4 structure containing cubic and tetragonal phases formed after heat treatment at 300 °C. In addition, a third phase transition of Na3SbS4 is inferred after further heating at 600 °C. This phase structure contributes to the improvement of electrochemical performance by promoting increasing ionic conductivity to 0.54 mS cm?1 at room temperature (25 °C) and reducing activation energy to 0.076 eV. This work provides an affordable material with good electrochemical properties and not only simplifies the preparation but also greatly reduces the risk of the process. 相似文献
36.
《Ceramics International》2022,48(22):33092-33100
CeNbO4+δ ceramics have attracted extensive research interest because of their unique mixed ion-electron transport characteristics and interesting structure-functional characteristics caused by the difference in oxygen ion content. Although the change of oxygen ion content brings rich redox properties, it also causes serious crystal transformation and abnormal electrical transport properties. In order to obtain stable structure and excellent electrical transport properties, the directional regulation of the oxygen ion content has been realized through introducing Al2O3 and high temperature aging. After 600 h of aging at 1073 K, the prepared composite ceramics not only obtain a stable structure without crystal transformation, but also show good negative temperature coefficient (NTC) thermistor characteristics in the temperature range of 473 K–1273 K, in which the linear fitting maximum Pearson's r of the relationship between lnρ and 1000/T can reach 99.97%. The proposed method provides a new thought for the design and application of high-temperature electronic ceramics. 相似文献
37.
《Ceramics International》2022,48(6):7344-7361
Zirconium diboride (ZrB2) and silicon carbide (SiC) composites have long been of interest since it was observed that ZrB2 improved the thermal shock resistance of SiC. However, processing of these materials can be difficult due to high and different sintering temperatures and differences in the thermodynamic stability of each material. ZrB2–SiC composites have been processed in a variety of ways including hot-pressing, spark-plasma sintering, reactive melt infiltration, pack cementation, chemical vapor deposition, chemical vapor infiltration, stereolithography, direct ink writing, selective laser sintering, electron beam melting, and binder jet additive manufacturing. Each manufacturing method has its own pros and cons. This review serves to summarize more than 60 years of research and provide a coherent resource for the variety of methods and advancements in development of ZrB2–SiC composites. 相似文献
38.
《Ceramics International》2022,48(10):13524-13530
Thin film sensors are employed to monitor the health of hot-section components of aeroengine intelligence (for instance, blades), and electrical insulating layers are needed between the metal components and thin film sensors. For this purpose, the electrical insulation characteristics of an yttria-stabilized zirconia (YSZ)/Al2O3 multilayer insulating structure were investigated. First, YSZ thin films were deposited by DC reactive sputtering at various substrate temperatures, and the microstructural features were investigated by scanning electron microscopy and X-ray diffraction. The results indicate that the micromorphology of the YSZ thin film gradually became denser with increasing substrate temperature, and no new phases appeared. The compact and uniform topography of the YSZ thin film improved the insulation properties of the multilayer insulating structure and enhanced the adhesion of the thin film sensors. In addition, the electrical insulation properties of the YSZ/Al2O3 multilayer insulating structure were evaluated via insulation resistance tests from 25 to 800 °C, in which the YSZ thin film was deposited at 550 °C. The results show that the insulation resistance of the multilayer structure increased by an order of magnitude compared with that of the conventional Al2O3 insulating layer, reaching 135 kΩ (5.1 × 10?6 S/m) at 800 °C. Notably, the insulation resistance was still greater than 75 kΩ after annealing at 800 °C for 5 h. Finally, the shunt effect of the YSZ/Al2O3 multilayer insulating structure was estimated using a PdCr thin film strain gauge. The relative resistance error was 0.24%, which demonstrates that the YSZ/Al2O3 multilayer insulating structure is suitable for thin film sensors. 相似文献
39.
《Ceramics International》2022,48(3):3762-3770
Cf/Hf0.5Zr0.5C-SiC composites were prepared by introducing Hf0.5Zr0.5C matrix (11 cycles) and SiC matrix (9 cycles) into the carbon cloth preform through precursor impregnation and pyrolysis (PIP) process. The influence of the introduction time of SiC matrix on the microstructure and mechanical properties of Cf/Hf0.5Zr0.5C-SiC composites was studied, and the results show that with the increase of the PIP cycles of the SiC matrix introduced before Hf0.5Zr0.5C matrix, the composite open porosity decreased, and the flexural strength and modulus presented an obvious upward trend. CS45 sample, which has 4 cycles of PIP SiC introduced in advance, has the highest flexural strength, flexural modulus and interfacial shear strength of 402.73 ± 35.73 MPa, 56.92 ± 3.97 GPa and 100.88 ± 7.79 MPa, respectively. Hf0.5Zr0.5C matrix has a loose and porous structure, so when more SiC matrix was introduced in advance, its covering effect on the surface of fibers led to less intra-bundle pores and thusly denser composite structure, and due to the compactness of SiC matrix, better overall bonding of fiber, interface and matrix was achieved, as well as better load transfer effect, which led to obvious interfacial debonding and cracking based on the in-situ SEM observation during flexural tests. While in the sample without pre-introduced SiC, the cracking occurred mainly between the interface and porous matrix and the overall performance of the material was poor. 相似文献
40.
通过对广西2021年度推广种植的野香优、广粮香2号、百香、丝香四个主要品种系列的早晚籼优质稻谷品种进行采样,按照《优质稻谷》《中国好粮油 稻谷》《广西好粮油 广西香米》标准中规定质量品质指标进行检测,并依据检测数据对四个主要稻谷品种在不同季节、不同种植区域以及同一种植区域不同种植季节品质变化情况进行对比分析研究,寻找优质稻因品种、产地、种植季节不同对其品质的影响规律,为优质稻谷品种的选育和推广种植工作提供科学依据和数据支持,促进广西优质粮食产业和“广西香米”产业进一步发展。 相似文献