共查询到20条相似文献,搜索用时 125 毫秒
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某超临界机组小汽轮机轴封回汽管道运行8.1×104 h时发生断裂。采用宏观形貌观察、金相检验、硬度检测、力学性能试验等方法分析了该回汽管道断裂的原因。结果表明:回汽管道所用TP304H奥氏体不锈钢的抗晶间腐蚀能力差,且在冷弯后未进行固溶处理,造成弯头处位错密度和残余应力增加,从而加速了含铬化合物的析出,形成了晶间贫铬区;在腐蚀环境及残余应力等因素综合作用下,管道内外表面萌生晶间腐蚀裂纹,裂纹沿贫铬区被弱化的晶界不断扩展,最终导致回汽管道发生晶间腐蚀断裂。 相似文献
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王敏 《现代制造技术与装备》2001,(4):42-43
1 前言 合金钢中的铝,常与铁、铬、钛元素伴随在一起,加之铝是具有两重性质的元素,所以在分离和测定铝时,至今还有困难。 过去我厂一直沿用《工厂实用化学分析》1980年版上册第238页“低合金钢中铝的测定—EDTA容量法”来测定铁铬铝电阻丝中的常量铝。但此法存在着一些不足之处:由于试样经酸溶完并经高氯 相似文献
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研究了加工过程中的表面污染、原材料的化学成分以及热处理工艺对304不锈钢焊管酸洗后表面外观质量的影响。结果表明:粉笔污染、原材料中铬含量的不足以及固溶处理中冷速较慢均会导致不锈钢焊管经酸洗后表面出现暗黄色花斑。 相似文献
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《机械工程材料》2017,(8)
采用扫描电子显微镜、透射电子显微镜、布氏硬度计、拉伸试验机等设备对不同温度固溶后Incoloy825合金的显微组织、力学性能及耐腐蚀性能等进行了研究。结果表明:当固溶温度在980~1 050℃之间时,合金的晶粒尺寸变化不明显,当固溶温度高于1 050℃时,晶粒尺寸以较快的速率增大;随着固溶温度的升高,合金的硬度和抗拉强度逐渐降低,伸长率不断增大;晶界析出相主要是由富含铬、钼的M_(23)C_6碳化物和含铬、镍、铁、钼的金属间化合物组成,晶界析出相的数量随着固溶温度的升高呈现先增多后减少的趋势,固溶温度为1 015℃时晶界析出相最多,此时合金的耐晶间腐蚀性能最差。 相似文献
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在石油、化工行业机械设备及管道的紧固联接中,为了确保联接的牢固,严防腐蚀失效,不锈钢紧固件被广泛应用,其材质一般为铬不锈钢或铬镍不锈钢。铬不锈钢分为wc1=12%、wc1=17%和wc1=27%等种类;铬镍不锈钢中wc1=17%~20%,wni=8%~11%。铬镍不锈钢的抗腐蚀性能及力学性能比铬不锈钢高, 相似文献
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从化学预处理、除盐制水设备方面出发,对影响离子交换树脂再生酸、碱消耗的各种因素进行分析,针对防止和减少离子交换树脂污染问题,提出采用新型弹性满室固定床离子交换器等措施,来提高离子交换树脂工作交换容量,降低再生酸、碱消耗量。 相似文献
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原料乳中硫氰酸钠的检测研究 总被引:1,自引:0,他引:1
建立了原料乳中硫氰酸钠的检测方法。硫氰酸钠经三氯乙酸提取,与三价铁反应生成红色络合物,用分光光度计测定其吸光度,根据吸光度曲线确定硫氰酸钠含量。方法处理简单,易操作,回收率高,试验成本低,分析周期短,因此该方法可作为原料奶中硫氰酸钠的快速检测方法。 相似文献
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The work described in this paper is a study of the high temperature corrosion reaction of iron in oils containing phosphorus compounds such as the phosphite, phosphate, thiosulphate, acid phosphate and acid phosphite, by using the hot-wire method. The neutral type esters show very little chemical reactivity towards iron in marked contrast to the very high reactivity of the acid type esters and thiophosphite. X-ray analysis revealed basic iron phosphate, 2FeFe4(PO4)(OH)5, and iron sulfide as the main reaction products for the neutral type and acid type esters and thiophosphite, respectively. The surface polishing action, peculiarly attributed to phosphorus compounds, could not be confirmed in the present work. The results from X-ray analysis seem to support the iron phosphate lubrication mechanism of phosphorus type EP additives. Some considerations are given for the correlations between the chemical reactivity, load carrying capacity and anti-wear property of oils containing phosphorus compounds. As to the lubrication characteristics of chloride, sulfide, phosphide and phosphate films, some postulations are made. 相似文献
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非完全消化处理样品,即在低温下用浓硝酸一高氯酸(4+1)混合酸消解样品,再加入乳化剂TX-10溶解消化过程中所产生的油脂,可得黄绿色透明的样品溶液。建立了非完全消化一火焰原子吸收光谱法快速测定苦瓜中的钙、镁、铁、锌、铜的分析方法,对非完全消化法样品处理条件、干扰、混合酸及试液的物理性质与其空白溶液的一致性、检出限和特征浓度进行了考察。测定结果的相对标准偏差小于2.0%。本方法的测定结果与灰化法一致,相对误差小于2.4%。实验所测定钙、镁、铁、锌、铜元素的检出限分别是O.51、0.009、0.145、0.009、0.019μg/mL。 相似文献
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微波消解MPT-AES法测定茶叶中的Fe、Cu 总被引:4,自引:0,他引:4
本文用HNO3-H2 O2 微波消解法处理样品 ,用MPT -AES法测定茶叶中的Fe、Cu。详细考察测定铁、铜时的实验参数 ,进行系统优化 ,并考察共存离子的干扰情况。本方法测定铜、铁的检出限分别为 2. 0 7ng/mL、2. 8 78ng/mL ,线性范围分别为 0~ 10 μg/mL、0 . 1~ 10 0 μg/mL ,样品测定的加标回收率均在 96 . 12 %~ 10 1. 32 %之间 ,相对标准偏差均≤3. 16 %。实验结果表明MPT -AES测定茶叶中铜、铁含量方法简便、高效、消耗试剂少、空白值低、污染少、方法准确性高。 相似文献
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文章介绍了磺基水杨酸分光光度法测定土壤、沉积物中铁量,建立了盐酸-硝酸的消解体系、磺基水杨酸分光光度法,对土壤、沉积物中铁量进行测定的新方法,分析步骤合理。实验结果表明此分析方法操作简便,选择性好,灵敏度高,低环境污染,测试结果令人满意。对标准参考样品测定数据显示,本方法准确可靠,精度好。详细介绍了实验方法的过程,对实际工作中的分析者有一定的指导意义。 相似文献
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Corrosion and wear resistance characteristics of NiCr coating by laser alloying with powder feeding on grey iron liner 总被引:6,自引:0,他引:6
To reduce the mixed fuel induced excessive wear of the cast iron engine cylinder liners, research on laser alloying of NiCr alloy with powder feeding was performed to locally change both the composition and the microstructure of the liner. The research indicated that laser alloying of 75Ni25Cr on grey cast iron liner demonstrates sound alloying layers free of cracks and porosities. The microstructure of the alloyed layer is composed of pre-eutectic austenite and ledeburite. The alloying element Ni is mainly located in the austenite, while Cr is mainly in cementite. The average hardness is HV0.2500. The corrosion resistance of the alloyed layers in diluted H2SO4 solution and NaOH solution is dramatically improved compared to the grey cast iron. The relative wear resistance of the laser-alloyed 75Ni25Cr layer is 4.34 times of that of the grey cast iron. The improvements on the corrosion and wear resistance of the cast iron are attributed to the composition and microstructure change by laser alloying of 75Ni25Cr. Laser alloying can be a good solution to improve wear and corrosion resistance of the grey iron liners in mixed fuel environment. 相似文献
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为改善铁素体球铁曲轴毛坯切削加工性能,分析探讨了铁素体的固溶强化机理,对材料的化学成分、力学性能和金相组织进行了分析比较。结果表明,影响铁素体球铁曲轴硬度的主要元素是硅,在试验范围内,铁素体球铁硅含量与其硬度成正比;通过调整硅含量,严格控制球铁中其他元素的含量并保持基体中铁素体数量的一致性,可以达到控制曲轴硬度,使铸造的曲轴毛坯完全满足自动化生产线对其切削加工性能的要求。 相似文献
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Yuhan JIA Peng ZHAO Jun XIE Xuechun ZHANG Hongwei ZHOU Jianzhong FU 《Frontiers of Mechanical Engineering》2021,16(1):186-195
This paper presents a single-electromagnet levitation device to measure the densities and detect the internal defects of antimagnetic materials. The experimental device has an electromagnet in its lower part and a pure iron core in the upper part. When the electromagnet is activated, samples can be levitated stably in a paramagnetic solution. Compared with traditional magnetic levitation devices, the single-electromagnet levitation device is adjustable. Different currents, electromagnet shapes, and distances between the electromagnet and iron core are used in the experiment depending on the type of samples. The magnetic field formed by the electromagnet is strong. When the concentration of the MnCl2 aqueous solution is 3 mol/L, the measuring range of the single-electromagnet levitation device ranges from 1.301 to 2.308 g/cm3. However, with the same concentration of MnCl2 aqueous solution (3 mol/L), the measuring range of a magnetic levitation device built with permanent magnets is only from 1.15 to 1.50 g/cm3. The single-electromagnet levitation device has a large measuring range and can realize accurate density measurement and defect detection of high-density materials, such as glass and aluminum alloy. 相似文献