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《理化检验(物理分册)》2016,(12)
某锅炉用T91(10Cr9Mo1VNb)钢屏式过热器管在服役8×10~4h后发生爆裂。通过宏观分析、金相检验、硬度测试、扫描电镜及能谱分析,对其爆裂原因进行了分析。结果表明:由于过热器管长时过热首先产生局部鼓包,弯头处不断变形并达到蠕变断裂强度后产生爆裂,先断裂部位为塑性断裂,其余为脆性断裂;该屏式过热器管爆裂的主要原因是长时过热,导致管道组织发生了严重老化和显著蠕变,而弯头处氧化皮堆积使得蒸汽流量减小是导致管道长时过热的主要原因。 相似文献
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正一、管损原因分析1.蒸汽质量的影响在工况条件下输送过热蒸汽,蒸汽质量没有损失或损失较小,也就不存在供热管损或管损不高。但在工况条件下输送饱和蒸汽,管道散热损失会促使蒸汽汽化潜热的释放,从而产生凝结水。由于水的体积远小于蒸汽体积,蒸汽流量计计量不到,这部分无法计量的凝结水就形成供热管损。根据理论计算和有关资料介绍,当压力为0.6MPa的饱和蒸汽流经直径为100mm的具有良好保温层的管道时,在大气温度为10℃的条件下,每100m管长上每小时要凝结出约30kg凝结水。2.蒸汽状态变化给流量计带来计量误差 相似文献
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某电厂汽轮机在检修过程中发现多处叶片断裂,采用宏观分析、金相检验、断口微观分析和能谱分析等方法对汽轮机叶片的断裂原因进行了分析。结果表明:蒸汽和Cl-,S2-,Na+等与汽轮机叶片发生反应,在叶片上产生局部点腐蚀,形成腐蚀疲劳源;同时因叶片上存在离心力和蒸汽压力等复杂的周期性交变应力,最终造成汽轮机叶片发生腐蚀疲劳断裂。 相似文献
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采用断口分析、X射线能谱分析、痕迹分析及金相检验等试验方法对断裂的发动机加力点火喷嘴管进行了综合分析。结果表明:装配应力大导致喷嘴管产生疲劳裂纹,疲劳裂纹起始于喷嘴管与加力内圈总管管座连接处的焊接根部,喷嘴管断裂性质为起始应力较大的高周疲劳断裂;在发动机大修重新装配喷嘴管时存在漏检问题。 相似文献
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目前,碱法制浆是国内外造纸工业中普遍采用的制浆方法。碱回收技术不仅能有效地回收黑液中的碱,使黑液达到国家排放标准,减少污染,而且可利用黑液燃烧的热量生产蒸汽,而蒸汽和碱又可回用于造纸行业其他生产工序,具有很好的环保和经济效益。 相似文献
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一、引言机械行业中有许多构件是在腐蚀环境中运行的,这些腐蚀环境除石油化工中各种酸、碱强腐蚀性介质外,还包括一般的河水、高纯水、蒸汽,甚至海洋大气和工业大气。由于腐蚀环境和应力的共同作用,机械构件的抗裂能力明显地下降了,因而常发生应力腐蚀开裂(SCC)、腐蚀疲劳(CF)、氢脆(HE)等腐蚀断裂,严重地影响机械产品的质量和寿命。这些腐蚀断裂在机械构件的断 相似文献
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《理化检验(物理分册)》2017,(10)
通过宏观检验、化学成分分析、力学性能试验、金相检验、扫描电镜断口分析等方法,分析了某电厂水冷壁管断裂失效的原因。结果表明:该水冷壁管断裂是由疲劳裂纹扩展造成的,裂纹起源于水冷壁管与鳍片焊接的焊缝未熔合缺陷处,裂纹沿水冷壁管的向火侧与背火侧同时扩展,最终造成水冷壁管垂直于钢管轴向发生横向断裂;焊缝硬度偏高并且存在未熔合焊接缺陷是造成该次断裂失效的内因,电厂启停炉及负荷波动过于频繁是造成该次断裂失效的外因。 相似文献
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琥珀酰壳聚糖的制备及其与HL-60细胞亲和性的研究 总被引:1,自引:0,他引:1
以粘均相对分子质量700000和17500的高脱乙酰度壳聚糖为原料,通过吡啶催化制备N-琥珀酰壳聚糖(N-SUCC-CCTS),通过甲磺酸保护氨基制备O-琥珀酰壳聚糖(O-SUCC-CTS).应用异硫氰酸荧光素黄(FTTC)对合成的2种琥珀酰壳聚糖进行标记,荧光标记率分别为0.97%(O-SUCC-CTS)、0.66%(N-SUCC-CTS1.75)和0.34%(N-SUCC-CTS70).用流式细胞仪测定琥珀酰壳聚糖与人白血病HL-60细胞的结合能力,亲和性能力顺序为O-SUCC-CTS1.75>N-SUCC-CTS1.75>N-SUCC-CTS70.O-SUCC-CTS是一种很有潜力的抗肿瘤靶向载体. 相似文献
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ZnO thin films have been deposited by pulsed laser deposition (PLD) and ultrasonic spray pyrolysis (USP) method, respectively. X-ray diffraction and transmission electron microscopy characterizations indicate that ZnO film grown by PLD exhibits better crystallinity than that grown by USP. Photoluminescence spectra show that the near-band edge ultraviolet emission of film grown by PLD is narrower and shifts to higher energy, compared with that of film grown by USP. In the visible range, ZnO film grown by PLD exhibits four local level emission centered at 470 nm, 486 nm, 544 nm, and 613 nm, respectively, while the film grown by USP only presents a weak broad band emission centered at 502 nm. Hall measurement shows higher carrier density and lower hall mobility in ZnO film grown by PLD than that in film grown by USP. The higher density of intrinsic defects as well as higher crystallintiy is considered to account for the difference of photoluminescence in ZnO film grown by PLD with that in film grown by USP. 相似文献
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Fracture of shear bands in atactic polystyrene 总被引:1,自引:0,他引:1
Thick shear bands in polystyrene formed by compression could cause fracture or the formation of cracks by intersecting with themselves, by relaxing after the removal of the load, by propagating all the way to the side surfaces and by subsequent tensile deformation. The microstructural mechanisms involved in all these fracture processes are discussed. 相似文献
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Electron beam induced deposition (EBID) is a maskless nanofabrication technique capable of surpassing the resolution limits of resist-based lithography. However, EBID fabrication of functional nanostructures is limited by beam spread in bulk substrates, substrate charging, and delocalized film growth around deposits. Here, we overcome these problems by using environmental scanning electron microscopy (ESEM) to perform EBID and etching while eliminating charging artifacts at the nanoscale. Nanostructure morphology is tailored by slimming of deposits by ESEM imaging in the presence of a gaseous etch precursor and by pre-etching small features into a deposit (using a stationary or a scanned electron beam) prior to a final imaging process. The utility of this process is demonstrated by slimming of nanowires deposited by EBID, by the fabrication of gaps (between 4 and 7 nm wide) in the wires, and by the removal of thin films surrounding such nanowires. ESEM imaging provides a direct view of the slimming process, yielding process resolution that is limited by ESEM image resolution ( approximately 1 nm) and surface roughening occurring during etching. 相似文献
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Residual stresses induced by three scribing methods, diamond point scriber, laser scriber and diamond blade saw, are studied quantitatively by infra-red photoelasticity. It is clear that diamond blade saw scribing is most desirable, for residual stress induced by it is several times smaller than the stress caused by the other methods. The stress gradient differs between the laser scribed sample and the others, probably because of the difference in stress generation mechanism. Removing the damaged layer by etching reduces residual stress. The three scribing methods are also studied by the observation of defects after annealing and the results are compared with those determined by photoelastic measurement. 相似文献
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To improve the dispersibility of polycrystalline nanodiamond (ND) in solvents, the grafting of polymers and introduction of ionic groups onto ND surface via radical trapping by ND surface were investigated. The grafting of polyoxyethylene (POE) onto ND surface by trapping of POE radicals formed by the thermal decomposition of POE macro azo-initiator (Azo-POE) was examined. The polymer radicals formed by the thermal decomposition of Azo-POE were successfully trapped by ND surface to give POE-grafted ND. The effect of temperature on the grafting of POE onto ND was discussed. In addition, the introduction of cationic protonated amidine groups onto ND was achieved by the trapping of radicals bearing protonated amidine groups formed by thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride (AMPA). The anionic carboxylate groups was introduced onto ND surface by the trapping of the radicals bearing carboxyl groups formed by thermal decomposition of 4,4′-azobis(4-cyonovaleric acid) (ACVA) followed by the treatment with NaOH aqueous solution. The dispersibility of ND in water was remarkably improved by the grafting of POE, based on the steric hindrance of polymer chains and by the introduction of ionic groups, based on the ionic repulsion, onto ND surface. 相似文献
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铅锌尾矿用于中热水泥的制备 总被引:1,自引:0,他引:1
本文采用铅锌尾矿为原料烧制中热硅酸盐水泥,并与用粘土配料烧制的中热水泥进行对比。用差热分析测定熟料的易烧性;用X射线衍射分析研究了熟料的矿物组成;依据国标GB2022-80测量了中热水泥的水化热;通过砂浆和净浆实验测定了中热水泥水化后的强度;并用X射线衍射和扫描电镜对水化产物进行了分析。实验结果表明,使用铅锌尾矿来配料,可以提高熟料的易烧性,矿物形成良好。熟料掺入4%的石膏制得水泥,其性能符合GB200-2003规定的强度等级42.5中热硅酸盐水泥的各项标准,并且其后期强度高于用粘土配料的试样。 相似文献
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The influence exerted on the accuracy of coulometric titration by the composition of the supporting electrolyte solution in the titration step, by the way of stirring of the supporting electrolyte solution, by the weight of the aliquot of the solution being titrated, by the weight of the substance being titrated in the aliquot, by the kind of reductant, and by the solution compositions in the steps of oxidation and reduction of U-Pu mixtures was studied by spectrophotometry and coulometry. The optimum conditions for performing the analysis were found. 相似文献