WC—Co硬质合金刀片热丝法金刚石薄膜涂层附着力

用热丝法研究了ＷＣ－６％Ｃｏ硬质合金刀片金刚石薄膜涂层附着力。结果表明：采用温度为８０℃,（ＨＣｌ：ＨＮＯ３：Ｈ２Ｏ）（体积比）为１∶１∶１溶液对硬质合金刀片表面去Ｃｏ１５ｍｉｎ后,经４０ｕｍ金刚石粉及１．５ｕｍ金刚石加２０ｕｍＴａＣ混合粉进行超声预处理,结果表明,沉积的金刚石薄膜与硬质合金刀片基底具有良好的附着力,而经４０ｕｍ金刚石粉处理的薄膜涂层组织与附着力要好一些。     

多晶3C-SiC薄层的淀积生长及结构性能分析

采用ＨＦＣＶＤ生长法,以较低生长温度,在Ｓｉ（１１１）衬底上淀积３Ｃ－ＳｉＣ（１１１）薄层。用ＸＲＤ、ＶＡＳＥ、ＸＰＳ等分析手段研究了薄层的结构、光学常数、组分及化学键等性能。ＸＲＤ显示薄层具有明显的择优取向特征。ＶＡＳＥ测量出薄层的折射率为２．６８６,光学常数随深度的变化曲线反映出薄层的多层结构。ＸＰＳ深度剖面曲线表明薄层中Ｓｉ／Ｃ原子比符合ＳｉＣ的理想化学计量比,其能谱证明Ｃ１ｓ与Ｓｉ２ｐ成键形成具有闪锌矿结构的３Ｃ－ＳｉＣ。     

TiO2制备条件对光催化氧化活性的影响

半导体光催化剂,如ＴｉＯ２,在紫外光照射下,生成具有强氧化还原活性的电子和空穴,可使许多有机物降解为ＣＯ２和Ｈ２Ｏ,用于处理工业废水具有成本低,无二次污染等优点,是一种很有应用前景的废水催理方法［１,２］．制备高活性的ＴｉＯ２光催化剂是这种过程在处理...     

Interaction of water with the regenerated cellulose membrane studied by DSC

One to three endothermal peaks atributted to melting of bulk and interfacial water were observed by DSC in the regenerated cellulose — water system. The profiles of thermal effects depend on water content, time of conditioning, film pretreatment and the conditions applied during the preceding freezing-thawing cycles. The occurrence might be deduced of melting-crystallisation processes. A large amount of non-freezable strongly bounded water was also detected. Although cellulose absorbs water quickly after immersion, the structural changes consisting on ordering of polymer fraction occur during further conditioning due to increase in strength of water binding. Using the membranes in the separation module at 90°C causes weakening of these bonds. Differences between interaction of particular cellulose films with water can be detected during the first, the second and the third heating. This revised version was published online in July 2006 with corrections to the Cover Date.     

Relationship between the molybdenum phases and the conversion of n-butane over Mo/HZSM-5

The conversion of n-C₄H₁₀ was undertaken on MoO₃/HZSM-5 catalyst at 773–973 K and the phases of molybdenum species were detected by XRD. The XRD results show that bulk MoO₃ on HZSM-5 can be readily reduced by n-C₄H₁₀ to MoO₂ at 773 K and MoO₂ can be gradually carburized to molybdenum carbide above 813 K. The molybdenum carbide formed from the carburization of MoO₂ with n-C₄H₁₀ below 893 K is -MoC_1−x with fcc-structure, while hcp-molybdenum carbide formed above 933 K. During the evolution of MoO₃ to MoO₂ (>773 K) or the carburization of MoO₂ to molybdenum carbide (>813 K), deep oxidation, cracking and coke deposition are serious, in particular at higher reaction temperatures, these lead to the poor selectivity to aromatics. Aromatization of n-C₄H₁₀ can proceed catalytically on both Mo₂C/HZSM-5 and MoO₂/HZSM-5, the distribution of the products for the two catalysts is similar below 813 K, but the activity for Mo₂C/HZSM-5 is much higher than that for MoO₂/HZSM-5.     

Synthesis and reactivity of metal-containing monomers. 21. Synthesis of TiCl4 and VCl4 complexes with azobisisobutyronitrile and studies of their thermal decomposition

Complexes of azobisisobutyronitrile (AIBN) with titanium tetrachloride and vanadium tetrachloride have been synthesized and characterized. It was demonstrated that Ti(IV) and V(IV) form equimolar complexes with AIBN, with nitrile ligands located incis positions in the coordination spheres of metal atoms. Kinetics of thermal decomposition of free and complexed AIBN were studied and compared. The gas evolution rate was measured in the presence of tetrabutoxytitanium, which does not react with AIBN. It was demonstrated that complexing leads to a marked increase of the rate constant of AIBN thermal decomposition.Institute of Chemical Physics, Chernogolovka, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1746–1754, August, 1992.     

钇提高YT14硬质合金耐磨性的机制

研究了不同Ｙ添加量对ＹＴ１４硬质合金显微组织、结构和耐磨性的影响。结果表明，在ＹＴ１４硬质合金中添加微量Ｙ，可显著提高合金的耐磨性。Ｙ的主要作用是均匀细化碳化物相和Ｃｏ相；提高Ｃｏ粘结相中Ｗ、Ｔｉ元素的固溶量及αＣｏ相所占的体积分数，从而提高Ｃｏ粘结相的强韧性；Ｙ在合金中形成Ｙ２ＷＯ６，表明Ｙ还可还原和清除碳化钨表面氧化膜，增强Ｃｏ粘结相与硬质相之间的结合强度     

Products of lithium interaction with nanostructured oxides SnO2-TiO2 and mechanism of charge-discharge of electrodes in a lithium-ion battery

Products of lithium interaction with thin-film nanostructured SnO₂-TiO₂ (ST) oxides are studied with the aid of x-ray diffraction analysis and Moessbauer spectroscopy on the ¹¹⁹Sn nuclei. Electrochemical properties of a series of the ST electrodes with different concentrations of TiO₂ varied from 0 to 20 mol % are also examined. It is concluded that the specific feature of the charge-discharge mechanism of the ST electrodes is a significant participation of oxygen in reversible reactions during insertion and extraction of lithium as compared with an alloying mechanism of operation of tin-containing anodes. The leading role in this is played by titanium oxide. Remaining stable towards reduction by lithium, it facilitates the holding of the neighboring layers of SnO₂ in a nanodisperse state and in an oxidized state. The effect of a decrease in the capacity degradation in modified TiO₂ electrodes, which is discovered in this work, is attributed to the hampering of the growth of nanocrystallites of β-Sn by interlayers of tin and titanium oxides mentioned above.     

Underpotential deposition studies of copper on glassy carbon

Studies on the deposition and dissolution of copper from 0·5 M sulphuric acid solutions onto glassy carbon (GC) using potential sweep techniques indicated that an additional peak occurs at higher positive potentials than the bulk stripping peak. This peak is identified as due to the stripping of underpotential deposited (UPD) copper. Results of investigations on the effect of sweep rate, deposition potential and time of deposition on the peak characteristics of UPD and bulk deposited copper are also reported.