热压碳化硼氧化行为及其对摩擦特性的影响

研究了热压碳化硼在973－1273K的氧化行为及其对摩擦性能的影响。氧化试样用X射线衍射分析其成分。用电子显微镜观察其微观形貌。结果表明,氧化试样表面生成一层薄而透明的B2O3薄膜。由于B2O3与B4C材料的热膨胀系数相差甚远,因而冷却时发生龟裂B2O3继而与空气中的水蒸汽发生反应,生成白色的H3BO3。H3BO3是一种固体润滑剂,当其出现于碳化硼摩擦副表面,可将摩擦系数由未经氧化处理的B4C／B4C摩擦副的0．25－0．35降至0．05左右,但氧化温度达1273K时,由于表面氧化腐蚀较严重,可能造成表面颗粒剥落,不利于降低摩擦系数。     

Treatment of Fenton‐refractory olive oil mill wastes by electrochemical oxidation with boron‐doped diamond anodes

In this work, the electrochemical oxidation of an actual industrial waste with conductive diamond anodes has been studied. The wastewater is the effluent of a wastewater treatment plant consisting of a Fenton reactor followed by a settler and a sand filter, in which the wastes generated in an olive oil mill are treated. These wastes contain a residual chemical oxygen demand of nearly 700 mg dm^?3 which cannot be further oxidized with the Fenton process. The electrolyses were carried out under galvanostatic conditions, using a bench‐scale plant equipped with a single‐compartment electrochemical flow cell. Boron‐doped diamond (BDD) and stainless steel (AISI 304) were use as anode and cathode of the cell, respectively. The complete mineralization of the waste was obtained with high current efficiencies limited only by mass transport processes. This confirms that besides the hydroxyl radical‐mediated oxidation that occurs in the Fenton process, the electrochemical oxidation with conductive diamond electrodes combines other important oxidation processes such as direct electro‐oxidation on the BDD surface and oxidation mediated by other electrochemically formed compounds generated in this electrode. Copyright © 2006 Society of Chemical Industry     

硼对炭材料氧化行为的综合效应

综述了硼在炭材料中的抗氧化机理，并阐述了炭材料在氧化过程中的行为。硼对炭材料的氧化反应具有催化作用和保护作用的双重特征。     

EPR-Characterization of Carbon Inclusions in Boron Carbide

In boron carbide, the dependence of EPR line width (ΔB) with g = 2.0028 on the contents of free carbon, c_C, is used to determine the surface-to-volume ratio ( S / V ) of free carbon inclusions. Consecutive reduction of c_C was conducted by a method of low-vacuum oxidation at a range of temperatures. The amount of a free carbon (a graphite phase) in samples was measured by X-ray. Analysis of changes in ΔB (c_C) has shown that free carbon inclusions at the surface layer of polycrystalline boron carbide particles has S / V two times smaller than that of free carbon inclusions in the interior of polycrystalline boron carbide.     

掺硼金刚石阳极电催化降解新兴抗生素类污染物研究进展

抗生素类药物是目前水环境中出现的一类新兴有机污染物,具有难自然降解、环境刺激性、生物毒性及耐药性等特点,高效去除抗生素类污染物是近年来环境工作者重点探讨的内容。掺硼金刚石（boron-doped diamond,BDD）电极由于自身优异的物理和化学性质,被认作为目前电催化氧化水中有机污染物最为理想高效的阳极材料,但关于BDD阳极在新兴抗生素类污染物的研究情况尚未进行及时的总结。本文首先论述了BDD阳极在电催化氧化有机污染物的降解过程和基于强氧化性物种的电催化氧化机理,进而分析了BDD阳极在电催化降解水中新兴抗生素类污染物的研究进展,探讨了影响抗生素类污染物电催化降解过程的关键影响因素,总结了BDD阳极材料的开发情况,同时,总结了以BDD阳极电催化氧化为基础发展而来的其他水处理联合方法,最后,进一步展望了BDD阳极在未来电催化降解抗生素类污染物存在的问题及未来的重点发展方向。     

锆刚玉莫来石—氮化硼复合材料的抗氧化性能研究

推导了锆刚玉莫来石－氮化硼复合材料１０００－１２００℃温度范围内的氧化动力学模型，并用实验数据予以验证。     

激光轰击法制备纳米金刚石的提纯研究

用Nd：YAG脉冲激光轰击循环水中的石墨细微颗粒悬浮液的方法已成功制备出纳米金刚石粉末，但在产物中存在着大量的原料残余。为了从混合物中获得纳米金刚石，分别用热选择空气氧化法和化学酸氧化法（不同浓度）来提纯产物混合粉末中的纳米金刚石。通过对处理后样品进行热失重曲线和透射电镜分析，比较这两种提纯方法的结果，最终得出结论：采用热选择空气氧化法不能够有效提纯激光轰击法所制备的纳米金刚石；用纯高氯酸作为氧化剂可以有效地提纯激光轰击法制备的纳米金刚石。     

碳化硼合成工艺及其产业化

介绍了碳化硼合成工艺的三种合成方法,重点论述了工业上生产碳化硼主要采用的碳热还原法。展示了碳化硼行业产业化的可喜前景。     

三氟化硼的合成及工艺路线选择

论述了三氟化硼的多种合成方法,根据我国实际情况选择了4种工艺,既可用于实验室制备,也可用于工业化的生产。     

Replacement of Flake Graphite in Aluminacarbon Refractories by Hexagonal Boron Nitride

Three kinds of composite alumina refractories were prepared with tabular alumina （3-1 and 1-0 mm） as aggregates,tabular alumina powder,α-Al2 O3 micropowder,and Si powder as matrix,adding 3 mass％ hexagonal boron nitride （h-BN）,3 mass％ flake graphite and 10 mass％ flake graphite,respectively.Cold physical properties,hot modulus of rupture,oxidation resistance,thermal shock resistance and slag corrosion resistance of the specimens were compared.The results show that：（1） physical properties and hot modulus of rupture of Al2 O3-h-BN refractories are slightly different from those of low carbon Al2 O3-C refractories,but better than those of traditional Al2 O3-C refractories with 10 mass％ graphite ; （2） Al2 O3-h-BN refractories have better thermal shock resistance and oxidation resistance than the carbon containing refractories,while similar slag resistance with low carbon Al2 O3-C refractories ; （3） h-BN can replace flake graphite as a starting material for the preparation of composite alumina refractories,considering the overall properties of the material.     

炭/炭复合材料抗氧化研究进展

C／C复合材料的高温氧化性能限制了其在高温领域的广泛应用。本文简要介绍了C／C复合材料的氧。化机理及两种主要的抗氧化技术，即抗氧化涂层技术和内部抗氧化技术，并就涂层的结构和发展趋势作了简要介绍。介绍了添加抑制剂磷和硼对C／C复合材料的高温氧化抑制，重点分析了将硼引入C／C复合材料的方法及硼在其中的接触氧化抑制和优先分配。对C／C复合材料的最新进展情况作了简要介绍，并对C／C复合材料高温抗氧化的研究方向提出自己的看法。     

氧化物/BN可加工复相陶瓷的高温氧化行为及表面裂纹修复

研究了2种可加工复相陶瓷Al2O3／BN和Y-ZrO2／BN在不同温度下的氧化行为及其热处理损伤修复。结果表明：高温时Al2O3／BN表面氧化生成致密的硼酸铝(Al18B2O33)氧扩散障碍层,并且与基体形成强结合的梯度抗氧化涂层,阻止了氧气向材料内部的快速扩散,因而具有良好的自愈合抗氧化性。而Y-ZrO2／BN复相陶瓷由于不能形成有效的氧化屏蔽,抗氧化性较差。2种复相陶瓷在900℃热处理后,表面形成的液态B2O3膜使压痕裂纹均得到愈合,压痕强度从热处理前的162MPa(Al2O3／BN)和336MPa(Y-ZrO2／BN)分别增加到热处理后的406MPa和585MPa。但在1100℃热处理2h后,由于过度的氧化会使Y-ZrO2／BN失去裂纹愈合的效果,压痕强度迅速下降。     

High-temperature oxidation of BN-coated sylramic SiC fibers in dry and wet atmosphere

The oxidation behavior of SiC Sylramic fibers coated with chemically vapor deposited Si-doped boron nitride (BN) was investigated at temperatures between 800 and 1200°C in dry and wet O₂ atmospheres. Thermogravimetric analysis was used to study the oxidation kinetics of the fiber and the influence of the BN layer and the environment. The morphology and composition of the thermally grown oxide scale was determined posttest by scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry. This study gives new insights into the synergistic effects of BN and water vapor on the oxidation behavior SiC Sylramic fibers. The vulnerability of the BN fiber interphase and the behavior of the fiber under conditions relevant to high-temperature turbine applications are discussed.     

Synthesis and inorganic conversion of polyborodiphenylsiloxane

Polyborodiphenylsiloxane (PPBSO) was reported to play significant roles in the preparation of advanced SiC ceramics as a precursor initiator, sintering binder and boron introducer. However, neither the effect of this important raw material on the pyrolysis process nor the evolution of boron has been clarified. This study synthesized PPBSO as a preceramic polymer and thoroughly investigated the constitutional and structural evolutions during organic-to-inorganic conversion. Boron was found to transform into the B(OSi)₃ structure fully at 1300 °C, and this structure played an important role in increasing the Si content (from 18.51%_wt to 35.84%_wt) by forming a viscous fluid barrier that reduced the gaseous release, which led to an increase in the vapor pressure and a reduction in the Si–O–C phase decomposition according to the Le Chatelier principle. The dominant B–O–C phase that was observed at 1000 °C transformed into a B(OSi)₃ structure, and high-pressure-formed BC₄, detected via Raman spectroscopy, was the result of the partial pressure increase. A crystallization-promoting effect of free carbon in the presence of boron was also detected via Raman analysis. This study extensively describes the role of boron in the silicon carbide ceramic conversion process and will be of substantial benefit for the fabrication of high-performance ceramic materials.     

Electrochemical incineration of dyes using a boron‐doped diamond anode

The electrochemical oxidation of a synthetic wastewater containing the model dyes alizarin red (an anthraquinone) and Eriochrome black T (an azoic compound) has been studied on a boron‐doped diamond electrode (BDD) by both cyclic voltammetry and bulk electrolysis. The influence of the current density and dye concentration were investigated. The results obtained show that complete chemical oxygen demand (COD) and colour removal was obtained for both wastewaters. However, the nature of the pollutant, and specially the presence of functional groups (such as the azoic group) seems to strongly influence the performance and efficiency of the electrochemical process. The electro‐oxidation of alizarin red behaves as a mass‐transfer‐controlled process. In such a system, an increase in the current density leads to a decrease in the current efficiency. This can be explained by direct or hydroxyl radical mediated oxidation. The contrary tendency has been observed in Eriochrome black T electro‐oxidation. In this case, higher efficiencies were obtained working at high current densities. This may indicate that the mediated oxidation by electrogenerated reagent (such as peroxodisulphate) is the main oxidation mechanism involved in Eriochrome black T treatment. These compounds have a longer average lifetime than hydroxyl radicals, and it allows the reaction to be extended to the whole wastewater volume. This study has shown the suitability of the electrochemical process for completely removing the COD and total organic carbon and effectively decolourising of wastewaters containing synthetic dyes. Copyright © 2007 Society of Chemical Industry     

臭氧氧化处理炼油废水的生化处理出水

采用臭氧氧化法处理经三级生化处理后生化性很差的炼油废水,研究了臭氧氧化法处理废水较佳的反应条件和反应规律。试验结果表明,在最佳的反应条件下,在进水COD的质量浓度为160mg/L时,经臭氧氧化处理后,废水的COD降低40%以上,BOD5与COD的质量比从0.13提高到0.3以上,废水满足进入生化系统进行进一步处理的水质要求。     

Preparation and properties of borosiloxane gels

Hybrid gels were synthesized from modified silicon alkoxides (R‐Si(OEt)₃, R?H, Me, Vi) and triiso‐butylborate (B(O? R′)₃, R′ = isoBu). The obtained gels were characterized by Fourier‐transform infrared (FTIR), nuclear magnetic resonance (NMR), elemental analyses, X‐ray diffraction (XRD), and scanning electron microscopy (SEM). Boron atoms in the precursors were homogeneously dispersed in the siloxane network via Si? O? B bonds. The effect of the boron load on oxidation resistance of the gels, and the pyrolysis behavior of the borosiloxane gels with different substituents on silicon, were investigated using various techniques. The experimental results suggest that the addition of a proper fraction of boron alkoxide to the precursors can improve the oxidation stability of the gels, and decrease the weight loss of the samples to 6.9 wt % at 1000°C under air. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 719–724, 2006     

组合氧化法深度处理煤制甲醇污水的实验研究

采用Fenton-NaClO组合氧化法对煤制甲醇污水进行深度处理。确定了最佳的Fenton氧化条件:H_2O_2投加量为90 mmol/L,Fe~(2+)浓度为30 mmol/L,p H=4,反应时间为60 min。最佳的NaClO氧化条件:p H=6,NaClO浓度为40 mmol/L,反应时间为60 min。经Fenton-NaClO组合氧化法处理后,出水COD、氨氮分别从280、130 mg/L降到43、8 mg/L,均可满足《污水综合排放标准》(GB 8978—1996)中规定的一级排放标准。     

硼氢化反应合成聚硼硅氮烷和热压成型-热解制备SiBCN陶瓷

对甲基乙烯基二氯硅烷(MeViSiCl2)进行氨解形成聚甲基乙烯基硅氮烷(PMVS),进而用二甲基硫醚硼烷(BH3-SMe2)和PMVS进行硼氢化反应,合成出SiBCN陶瓷的前驱体聚硼硅氮烷(polyborosilazane,PBSZ)。Fourier红外光谱分析表明:合成的PBSZ中有C-B-C和Si-N特征吸收峰,分别对应HC-B(CH)-CH和≡Si-NH-基团;11B和29Si的核磁共振分析产物中有BC3,SiN2C2,SiN3C和SiC3N等结构单元,这些光谱结果表明合成的产物为PBSZ。对PBSZ热压成型,在1000℃氩气中热解制备出SiBCN陶瓷体。PBSZ的热重分析表明:氩气中1300℃热解的陶瓷产率为52.6%。陶瓷局部致密,表明用前驱体热解法有望获得致密的SiBCN陶瓷体。     

Elimination of boron and lithium coexisting in geothermal water by adsorption-membrane filtration hybrid process

Direct release of geothermal waters to the environment may cause some damages to some plants because they contain toxic species such as boron, arsenic, fluoride etc. along with valuable minerals including lithium. In this study, a hybrid process combining adsorption and membrane filtration was used to separate boron and lithium simultaneously from geothermal water. According to the results obtained, separation efficiencies for lithium and boron from geothermal water were 100% and 83% using boron selective ion exchange resin Dowex XUS-43594.00 and lithium selective λ-MnO₂ adsorbent, respectively. The kinetic data of lithium and boron adsorption have been evaluated using pseudo-first order and pseudo-second-order kinetic models.