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1.
超微金赋存状态的研究   总被引:12,自引:0,他引:12  
叶先贤  孙振亚 《黄金》1991,12(7):1-5
本文利用EPMA、SEM/EDX、及TEM/EDX等分析技术,对我国某些卡林型金矿中金的赋存状态进行了研究。这些分析方法的综合运用,明确揭示出所谓的“不可见金”是由几十埃到几千埃不同粒级构成的被包裹于黄铁矿、含砷黄铁矿、粘土及石英等载金矿物中的超微金粒,并在粘土中首次获得45(?)的自然金颗粒。此研究结果,为评价金的存在形式提供了科学依据。  相似文献
2.
在高粘度介质中制备纳米钴粉   总被引:6,自引:0,他引:6  
曾效舒  韩丽芬  刘文 《江西冶金》2003,23(5):7-9,14
在两种介质中分别加入硝酸钴,碳酸铵进行制备纳米钴粉的溶胶凝胶反应。把获得的氧化钴粉放在700℃-850℃的氢气气氛下进行了还原处理。用透射电子显微镜检测,结果表明用这种方法可以制得纳米氧化钴粉。还原反应使纳米钴粉体的粒径较之氧化钴粉体的粒径增加了1—1.5倍。  相似文献
3.
 The nanocrystalline microstructure of the surface of 316 stainless steel (316SS) induced by surface mechanical attrition treatment (SMAT) was determined by X ray diffraction (XRD) and scanning electron microscopy (SEM). The technique of hydrogen embrittlement was first used to obtain the information of the brittleness cleavage plane. The effects of SMAT and the following annealing process on the corrosion behavior of 316SS were investigated by potentiodynamic polarization curves and potentiostatic critical pitting temperature measurements. The results demonstrated that the nanocrystalline layer with an average grain size of 19 nm was produced. However, there were lots of cracks on the surface, which led to the degradation in the corrosion resistance of 316SS after SMAT. Nevertheless, after annealing treatment, the corrosion resistance of the nanocrystalline surface had been improved greatly. The higher the annealing temperature, the better was the corrosion resistance.  相似文献
4.
 The corrosion behavior of the 110S tube steel in the environments of high H2S and CO2 content was investigated by using a high-temperature and high-pressure autoclave, and the corrosion products were characterized by scanning electron microscopy and X-ray diffraction technique. The results showed that all of the corrosion products under the test conditions mainly consisted of different types of iron sulfides such as pyrrhotite of Fe0. 95S, mackinawite of FeS0. 9, Fe0. 985S and FeS, and the absence of iron carbonate in the corrosion scales indicated that the corrosion process was controlled by H2S corrosion. The corrosion rate of the 110S steel decreased firstly and then increased with the rising of temperature. The minimum corrosion rate occurred at 110 ℃. When the H2S partial pressure PH2S below 9 MPa, the corrosion rate declined with the increase of PH2S. While over 9 MPa, a higher PH2S resulted in a faster corrosion process. With the increasing of the CO2 partial pressure, the corrosion rate had an increasing trend. The morphologies of the corrosion scales had a good accordance with the corrosion rates.  相似文献
5.
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
6.
16MnR中板冷弯分层开裂问题分析   总被引:2,自引:0,他引:2  
在通常情况下,冷弯开裂时裂纹方向是沿垂直于弯曲弧方向延伸的。本文针对16MnR中板在冷弯时产生的裂纹方向近似平行于弯曲弧方向的现象,利用金相显微镜、电子显微镜和X射线能谱仪对其组织进行了针对性分析,并提出了相关观点。  相似文献
7.
粉末试样的扫描电镜观察方法   总被引:2,自引:1,他引:1  
阐述了用扫描电镜研究粉末试样的分散技术、固定方法和镀膜技术。对于各种不同粒度的粉末试样,推荐了不同的既简便又可靠的制备方法。研究了用扫描电镜观察粉末试样时加速电压和束流的选择。通过研究和试验获得了实用的试验技术和理想的观察结果。  相似文献
8.
A monolithic series of Cu-Mn-Ce oxides supported on cordierites with different Cu/Mn/Ce molar ratios were prepared by the in-situ sol-gel method without any binder. The catalysts were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and Brunauer-Emmett-Teller method (BET) and examined in the catalytic combustion of volatile organic compounds (VOCs). The results showed that the well-dispersed nanometer particles of mixed oxides adhered firmly...  相似文献
9.
 Transformation and coarsening of carbides in 2.25Cr-1Mo steel weld metal during tempering at 700 oC for different time intervals ranging from 1 to 150 h has been examined by transmission electron microscopy and scanning electron microscopy. M3C carbides were observed in the as-welded specimens and when tempered the precipitates were mainly composed of M3C, M7C3 and M23C6 carbides. A sequence for corresponding carbide transformation during tempering with initial precipitation of M3C and followed by M7C3 and M23C6 has been proposed. The precipitation of M7C3 with higher Cr content is the main factor contributing to the decrease of coarsening rate of precipitates after prolonged tempering. The decrease of hardness in the tempered specimens agreed well with the prediction of the weakening of precipitation strengthening due to the coarsening of carbides.  相似文献
10.
 Supermartensitic stainless steel (SMSS) is a new-style material has been introduced into the oil and gas industries to substitute more expensive duplex stainless steel for deep/ultra-deep well tubing applications. For improving mechanical properties of the certain chemical composition steel, a balance between strength and toughness must be achieved by controlling heat treatment. In this paper, the influence of tempering process on microstructure and mechanical properties of 00Cr13Ni4Mo SMSS was investigated. 600°C was chosen as the optimized tempering temperature from the quenching and different temperature tempering tests. The samples were kept at 600°C for 3h, 6h, 8h, 10h and 12h respectively, followed by air cooling. Scanning electron microscopy and X-ray diffraction examinations were conducted to analyze the microstructural evolutions. It revealed that the superior mechanical properties were achieved with 1040°C quenching (kept 0.5h +water cooling) and 600°C tempering (kept 3h +air cooling). Increasing isothermal tempering time could improve the toughness notably. It was considered that the property was correlated with the microstructure of tempered lath martensite and retained austenite. The more content of retained austenite, the higher toughness of the SMSS.  相似文献
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