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The present work aimed at using rare earth lanthanum salt and trimethoxy(viny)silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate. The corrosion resistance was assessed by electrochemical impedance spectroscopy (EIS) and neutral salt spray tests (NSS). Scanning electron microscopy (SEM) was used to characterize the sample surfaces. The organic coating adhesion on the panel was also investigated via varnishes-cross cut tests. The results indicated that rare earth and silane two-step treatment gave more effective anticorrosion performance than Cr, which also provided good paint adhesion. The coating formation mechanism was also discussed.  相似文献
采用金属原位统计分布分析技术研究了系列不锈钢板中Mn,Ti,Al,Nb等类夹杂物存在的类型及状态,夹杂物的含量、组成、尺寸及位置分布等。该系列不锈钢样品中,各夹杂元素的分布具有不同的特点:Mn元素的大颗粒夹杂多位于板的中心部位;Ti,Al夹杂在整个横截面内分布则比较均匀;Nb大颗粒夹杂倾向于板的上、下表面附近及中心处。通道合成技术研究表明:Mn夹杂颗粒主要以硫化锰的形式存在;Ti夹杂主要以碳硫化钛的形式存在。给出了各类夹杂物的含量、粒度分布、平均粒径及20μm以上大颗粒夹杂的比例。综合分析和评价了各样品中夹杂物存在的种类及数量。该原位统计分布分析方法应用于不锈钢板中夹杂物的分析结果与传统的方法如金相、扫描电境等具有很好的一致性。  相似文献
A complex film on hot-dip galvanized steel sheet (HDG) was prepared by immersing the sheet in 0.1wt.% Ce(NO3)3 solution and 5vol.% silane solution in turn. The corrosion protection of the complex film was evaluated by potentiodynamic linear polarization(LPR), electrochemical impendence spectra (EIS) and natural salt spray (NSS) tests and compared with that of single cerium film and silane film. The results showed that, the presence of these films on the zinc coating hindered corrosion reaction by reducing the rate of both anodic and cathodic reaction in the corrosion process, and the corrosion protection of the complex film was much better than that of single cerium film or silane film and closed to that of chromate film, because the polarization resistance Rp and electrochemical impendence were increased markedly. Microstructure and chemical composition of these pretreated films were also investigated by scanning electron microscopy (SEM) and AES.  相似文献
Influences of rare earth (RE) elements addition on thermal fatigue behaviors of AZ91 alloy were studied. Repeated heating and cooling cycles were applied on the samples at 170 and 210 ℃ to develop thermal fatigue cracks. Crack growth mechanisms and microstruc-tural influences were investigated by optical and scanning electron microscopy (SEM) as well as energy dispersive X-ray spectroscopy (EDS). Thermal fatigue behaviors were observed to improve successively by addition of the RE up to 2wt.%. This improvement was attrib-uted to the consummation of aluminum in melt by precipitation of the needle shaped A11IRE3 phases. This process was attributed to the re-duction of Mg17Al12 phase volume fraction and consequent decrease of the brittle Mg/Mg17Al12 interface which was the main reason for weak thermal properties of the alloy at rather high temperatures. Further additions of RE, however, reduced the thermal shock resistance of the samples by increasing the mean length of the brittle needle shaped phases.  相似文献
Upconversion properties of Y2O3:Er films prepared by sol-gel method   总被引:1,自引:1,他引:1  
Y2O3:Er3+ films were prepared by a simple sol-gel process. The structural properties of Y2O3:Er3+ flints were characterized with X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The results indicated that the Y2O3:Er3+ f'rims might have high upconversion efficiency because of their low vibrational energy. Under 785 and 980 nm laser excitation, the samples showed green (2H11/2→4I15/2, 4S3/2→4I15/2) and red (4F9/2→4I15/2) upconversion emissions. The upconversion mechanisms were stud-led in detail through laser power dependence. Excited state absorption and energy transfer process were discussed as possible upconversion mechanisms. The cross relaxation process in Er3+ was also investigated.  相似文献
Fe-based layer with Ti(CINI-x) particulates on Adamite roller surface was obtained by a 5 kW traverse-flowing CO2 laser cladding technology. The microstructures of the layer were detected by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microscopy analysis (EMPA). The tests of wear resistance was carried out on the test machine. It was seen that a good metallurgical bonding between the coating and the substrate was achieved. The microstructure contains bulky dendritic crystal and small size Ti(CINI-x) grains that are uniformly distributed in the solid solution matrix. The wear tests showed that the laser coating provided an excellent wear resistance property at room temperature.  相似文献
某铅银渣物相及锗的赋存状态研究   总被引:1,自引:1,他引:0  
李和平  王昭云 《云南冶金》2010,39(6):51-53,60
应用X-射线衍射仪、扫描电子显微镜等手段,研究了某铅银渣的物相组成及锗在各物相中的赋存状态,发现了独立锗矿物羟锗铁矿,计算出锗在各物相中的分配率。根据研究结果提出铅银渣中回收锗的有效途径是使锗和铁分离,还原焙烧对回收锌和锗有利的技术路线,为改进锗回收工艺,提高锗浸出率提供了可靠的科学依据。  相似文献
Rare earth ions La3+ and Eu3+ co-doped TiO2 photocatalyst (La-Eu/TiO2) was prepared by sol-gel method, and characterized by various techniques such as X-ray diffraction (XRD), specific surface area and porosity (BET and BJH), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the La-Eu/TiO2 was evaluated by the degradation of methylene blue (MB) under UV light irradiation. The catalyst had a relatively uniform particle diameter distribution in the range of 40–60 nm. When calcining at 600°C, the XRD patterns of La-Eu/TiO2 indicated the anatase phase, while the XPS patterns showed the Ti4+, La3+ and Eu3+ ions existence. The DRS spectra showed red shift in the band-gap transition. The experimental results of MB degradation demonstrated that the photocatalytic activity of La-Eu/TiO2 was significantly enhanced due to better separation of photogenerated electron-hole pairs.  相似文献
三维激光扫描技术在测绘采空区中的应用   总被引:1,自引:1,他引:0  
安全生产是各大矿山企业的首要目标,而采空区的存在对矿山的生产造成了安全隐患,同时也严重影响后续的矿体开采规划。如何准确掌握采空区资料,科学地揭示井下空区的几何特性及相互的空间关系对矿山安全和生产有着非常重要的意义。然而,空区测量存在人员、设备进入难,精度差、危险高等特点;而三维激光扫描技术恰恰克服了以上困难。以焦家金矿望儿山矿区为例,详细介绍了利用三维激光扫描技术实现矿山未知采空区的轮廓边界及空间定位,从而为进行空区治理及资源回采工作打下坚实的理论基础。  相似文献
The solidification process of AISI 304 stainless steel during cooling at a rate of 0.05 K/s has been observed in situ using a confocal scanning laser microscope (CSLM). The results show that the 8 phase appeared first in liquid steel, as the temperature decreased, the γ phase precipitated prior at δ-grain boundary at 1452. 2 ℃, the liquid steel disappeared at 1 431.3 ℃, and then the γ phase precipitated on the δ ferrite. Based on the Scheil-Gulliver solidification model, the solidification processes of AISI 304 stainless steel are simulated using the Scheil model in Thermo Calc, and the simulation results agree well with the results observed in the experiment.  相似文献
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