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991.
Zirconium alloys are active in the molten state and tend to react with the mold during casting. The casting technology of zirconium is not yet well established; especially in selecting the mold materials, which are difficult to determine. In the present work, the interfacial reactions between zirconium casting and casting mold were studied. The zirconium alloy was melted in a vacuum arc skull furnace and then cast into the graphite mold and ceramic mold, respectively. The zirconium casting samples were characterized using SEM, EDS and XRD with an emphasis on the chemical diffusion of elements. A reaction layer was observed at the casting surface. Chemical analysis shows that chemical elements C, O and Y from the mold are diffused into the molten zirconium, and new phases, such as ZrC, Zr30, YO1.335 and Y6ZrO11, are formed at the surface. In addition, an end product of zirconium valve cast in a yttria mold has a compact structure and good surface quality. 相似文献
992.
以一高位转换的框支剪力墙结构为实例,用Satwe和Midas Gen两种有限元软件对转换梁的内力和变形进行了分析比较,得出了两者的内力值有较大差别,而位移值则差别不大的结论。 相似文献
993.
In this paper, the effect of calcium aluminate cement (CAC) additions on the alkali activation of red clay brick waste (RCBW) was studied at room temperature and at 65 °C. RCBW was partially replaced with CAC (0–50 wt.%) and blends were activated with NaOH and sodium silicate solutions. The compressive strength evolution was tested on mortars and the nature of the reaction products was analysed by infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, microscopic studies and pH measurements. The results show that the use of CAC accelerates the activation process of RCBW so that 50 MPa were obtained in the blended mortars containing 40 wt.% CAC cured for 3 days at room temperature. CAC did not undergo normal hydration and only the C3AH6 phase was identified in the pastes blended with more than 30 wt.% CAC and cured at 65 °C, while the main reaction product was a cementitious gel containing Ca and Al from CAC. 相似文献
994.
995.
Rayees Ahmad Shiekh Ismail Ab RahmanSam’an Malik Masudi Norhayati Luddin 《Ceramics International》2014
A nanohydroxyapatite–silica powder was synthesized using an ethanol based sol–gel technique. The synthesized powder was incorporated into commercial glass ionomer powder (Fuji II GC) and characterized using FTIR, 29Si CP/MAS NMR, EDX and XRD spectroscopy. 29Si CP/MAS NMR results showed the presence of higher degree of cross-linking of silyl species between silica and GIC, which makes the Nano-HA–Silica–GIC composite much stronger. High-resolution transmission electron microscopy (TEM) and scanning electron microscopy (TEM) was employed to investigate the morphology of the synthesized powder. Results revealed that higher content of nanosilica produced a denser and stronger GIC. Thus, the application of nanohydroxyapatite–silica–GIC with improved properties are envisioned to be of great clinical importance, especially in stress bearing areas. 相似文献
996.
对汽车隔热板进行了工艺分析,结合客户需求和制品特点,确定了制品的分型面和注塑设备,并对成型零件、浇注系统、推出机构等进行了设计,模具运行可靠,生产的制品达到了使用要求。 相似文献
997.
高层建筑钢筋混凝土梁式转换层施工技术分析 总被引:1,自引:0,他引:1
近年来,我国高层建筑不仅数量越来越多,功能和用途也日趋丰富。由于每个高层建筑的建设标准和功能要求不尽相同,在此背景下,梁式转换层过渡结构就应运而生,并在工程实践中得到了广泛应用。 相似文献
998.
Peiyang Shi Haonan Shi Chengjun Liu Maofa Jiang 《Canadian Metallurgical Quarterly》2018,57(2):168-175
Oxide layer formed on stainless steel surface can result in a decrease in surface quality. Thus, it must be removed. In this paper, we investigated the effect of different pickling processes on removal of the oxide layer. Ferritic stainless steel was used as raw material. After it received annealing treatment, the components and structure of the oxide layer formed on its surface were studied. Then, the annealed stainless steel was pickled in hydrochloric acid solution system and mixed acid solution system, respectively. Results are as follows. The oxide layer on stainless steel surface has a thickness of 15–35?μm. With increase in hydrochloric acid concentration in hydrochloric acid pickling solution, the weight loss rate of stainless steel increases and is always greater than that in mixed acid pickling system. In addition, the surface of the stainless steel pickled in hydrochloric acid is smoother than that pickled in mixed acid. Furthermore, compared with channels in the oxide layer created during mixed acid pickling, those created during hydrochloric acid pickling are more, leading to shorter removal time. These results are important for increasing the pickling efficiency and improving the surface quality of stainless steel. 相似文献
999.
1000.
The Electrophoretic Deposition (EPD) technique has been applied to the preparation of a porous La0.995Ca0.005NbO4/Ni composite anode layer, deposited on a porous pre-sintered La0.995Ca0.005NbO4/Ni support. Powders of La0.995Ca0.005NbO4 and NiO were suspended in a solution of acetylacetone, iodine and water. Selectivity in the composition of the deposited layer was analyzed as a function of the suspension compositions and deposition conditions. A quasi-symmetrical cell was produced by depositing La0.995Ca0.005NbO4 electrolyte layer on the anode layer by EPD, and by applying a porous La0.995Ca0.005NbO4/Ni counter electrode on the dense electrolyte layer by brushing. The performance of the electrodes was evaluated by electrochemical impedance spectroscopy in 3% wet H2. 相似文献