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1.
本文通过测量ＣＯ３Ｔｉ、Ｎｉ３Ａｌ、Ｆｅ３Ａｌ、ＴｉＡｌ四种金属间化合物在氧气、氢气中在２×１０－４／ｓ形变速率下的拉伸性能,研究了其在氢气中的室温环境脆性．研究结果表明,上述四种金属间化合物在Ｈ２中的脆化程度（用氢脆因子ＩＨ２＝［（δＯ２－δＨ２）／δＯ２］×１００％表示）是不同的,其大小依次为Ｃｏ３Ｔｉ＞Ｆｅ３Ａｌ>ＴｉＡｌ.其脆化程度的差异用金属间化合物中基体金属对氢气的催化裂解作用的强弱进行了很好的解释． 相似文献
2.
曹本春 《中学生数理化(高中版)》2012,(8)
氧化还原反应中氧化性、还原性强弱的比较是中学化学的重点也是难点.氧化性、还原性强弱主要取决于物质得失电子的难易程度而不是取决于得失电子数目的多少,当然还跟反应的条件如溶液的酸碱性、反应物的浓度、温度、催化剂等因素有关,我们可以从以下几个方面进行判断.
一、根据金属、非金属活动性判断
(1)根据金属活动顺序表判断
金属原子还原性:K＞Ca＞Na＞Mg＞Al＞Zn＞Fe＞Sn＞Pb＞ (H) ＞Cu＞ Hg＞Ag＞Pt＞Au.
对应阳离子氧化性:K+＜Ca2+＜Na+ ＜Mg2+＜Al3+ ＜Zn2+ ＜Fe2+ ＜Sn2+ ＜Pb2+＜(H+) ＜Cu2+＜Fe3+ ＜Hg2+＜Ag+. 相似文献
3.
研究了第一列过渡金属Ti,V,Cr,Mn,Fe,Co,Ni的乙酰丙酮化合物对环戊二烯与丙烯醛反应的立体选择性的影响。并在这些均相催化体系中添加三苯基膦,比较环加成产物立体构型的变化。 相似文献
4.
一、缺乏思维的深刻性例1假设用于修补铁轨的铝热剂中铝和四氧化三铁恰好完全反应,求此铝热剂和反应后的产物分别跟足量的稀硫酸反应时所放出的氢气的体积比(同温同压下)。错解铝热反应:8Al+3Fe3O4高温4Al2O3+9Fe8amol9amolAl、Fe分别与酸反应:2Al～3H2Fe～H28amol12amol9amol9amol故同温同压下产生H2的体积比为4∶3。评析看似思路、关系式以及计算都正确,且简洁流畅,无懈可击。然而,未考虑到铝热剂与硫酸反应后溶液中含Fe3+,Fe3+的氧化性强于H+,它必然先与铝反应。铝热反应:8Al+3Fe3O4高温4Al2O3+9Fe若设Al为8amol,则Fe3O4为3amo… 相似文献
5.
关于钠、镁、铝、铁、铜等几种金属的知识在化学教材中占有重要地位,一直是考题取材的重点.现将几种金属归纳复习.1 知识网络1)钠及其化合物间的转化关系2)镁及其化合物间的转化关系3)铝及其化合物间的转化关系4)铁及铁的化合物间的转化关系5)铜及其化合物间的转化关系2 主要考点分布①Na与水反应的现象;②Na2O2的性质及用途;③NaOH、Na2CO3及NaHCO3的性质与用途;④MgO、Al2O3的性质与用途;⑤Al2O3、Al(OH)3的两性;⑥Al(OH)3的用途;⑦铁三角间的转变;⑧Fe(OH)2的制备;⑨焰色反应;⑩Cu(OH)2的性质;金属的冶炼;有关计算:a.Na与… 相似文献
6.
穆振永 《河北理科教学研究》2004,(3):60-61
1 根据金属活动性顺序进行判断 常见金属原子的活动性顺序为:K CaNa Mg Al Mn Zn Fe Cr Ni Sn Pb(H)Cu HgAg Pt Au ①从左到右,金属原子的还原性逐渐减弱,对应金属阳离子的氧化性逐渐减弱; ②Fe3+氧化能力介于Hg2+、Ag+之间.2 根据非金属活动性顺序进行判断 常见非金属原子的活动性顺序为F O ClBr I S P C Si 相似文献
7.
考察了不同Ni担栽量的Ni/α-Al2O3催化剂对甲烷部分氧化的催化性能的影响和助剂Ce对Ni基催化剂性能的调变作用.采用沉淀法以NH3·H2O、Al(NO3)3·9H2O和Ni(NO3)3·6H2O为原料合成Ni/α-Al2O3凝胶,经过高温煅烧制备纳米级催化剂Ni/α-Al2O3粉末.通过固定床反应器进行催化剂的活性评价,并对其进行XRD和TPR分析.结果表明:8%Ni(质量分数)的Ni/α-Al2O3催化剂催化活性最佳,同时添加稀土Ce有助于提高催化剂的活性、选择性和稳定性. 相似文献
8.
化学计算常遇到这样的题 :比较相同质量的几种不同金属在同一条件下跟酸反应 ,置换出氢气的多少 .这类题目是有规律可循的 .( 1 )不同金属跟足量稀硫酸或盐酸反应时生成 1g氢气 ,所需要的金属质量为金属原子量金属与酸反应的化合价 .例 1 取Mg、Al、Zn 3种金属与足量的盐酸反应生成等质量的氢气 .则这 3种金属质量之比为 .解 :不同金属和足量的酸反应 ,生成等质量的H2 ,可设都生成 1gH2 ,则根据金属原子量金属与酸反应的化合价 得Mg∶Al∶Zn =2 42 ∶2 73∶6 52 =1 2∶9∶32 5.( 2 )用质量相同的不同金属 (设都为ag)跟足量的稀硫酸或… 相似文献
9.
在水热条件下,硝酸铒、硝酸钴和被修饰的咪唑二羧酸刚性配体反应,得到一个异核金属有机骨架化合物,其化学式为[Er2Co2(μ3-Hmimda)2(μ3-mimda)2·4H2O]n·2n H2O,(其中H3mimda代表1H-2-methyl-4,5-imidazole-dicarboxylic acid).X-ray单晶衍射分析表明,它属于单斜晶系,C2/c点群,具有波纹状的二维层状结构,二维层状结构再通过分子间作用力形成三维网格状的微孔结构.荧光测试显示,标题化合物在近红外区域显示饵(III)离子的特征发射荧光. 相似文献
10.
采用铸造法制备了 Fe-Ti-C/ZL108铝基复合材料,用SEM观察显微组织,进行了 EDS元素分析以及XRD物相分析,测试了力学性能.结果表明,增强相呈针状、板条状或团絮状,分布较均匀.增强体含量增加,针状和板条状的增强相形状及尺寸大小略有变化,由Al、Fe、Si反应生成,界面清洁;而团絮状的增强相逐渐长大,由Al、Ti、C生成,界面较模糊.增强相由Fe2SiTi、Al0.3Fe3Si0.7、Al4Si3C6等化合物组成;其反应机理为液-固反应.复合材料的力学性能因增强体承载、界面传载机制而提高. 相似文献
11.
The mechanism involving the effect of disorder/order transformation on the environmental embrittlement in gaseous H2 is summarized. It is shown that there is no hydrogen embrittlement in disordered state of Kurnakov type intermetallics in gaseous H2. However, the H2-induced environmental embrittlement for the ordered alloy having identical chemical composition becomes severer as the degree of the order increases. The results of testing on the ion gage turned on and off during tensile testing show that the more sensitive to H2-induced hydrogen embrittlement for ordered alloy than disordered one is attributed to the fact that atomic ordering may accelerate the kinetics of the catalytic reaction to produce more atomic hydrogen. The results on simultaneous hydrogen charging show that disordered alloys embrittled as hydrogen atoms are forced into the material implying that the embrittlement of ordered alloy in gaseous H2 is also due to the acceleration of the kinetics of catalytic reaction. The above suggestion was further verified by the adsorption tests of Ni3Fe intermetallics powder. It is shown that the amount of chemically adsorbed hydrogen in ordered state is significantly larger than that adsorbed by the disordered alloy, indicating that the more sensitive to H2-induced embrittlement in the ordered state of alloy is essentially due to the accelerated catalytic reaction. 相似文献
12.
In this paper the effect of alloying elements on the environmental embrittlement of Ll2 type intermetallics is summarized. The results show that the ductilizing effect of boron doping in Ni3Al is mainly to suppress the moisture-induced environmental embrittlement. The mechanism of this suppression effect is proved
to be related to its severely reducing the hydrogen diffusivity along the grain boundaries. However, the boron doping in Co3Ti alloys does not have the same effect of suppressing the environmental embrittlement. The different behavior of boron doping
in Ni3Al and Co3Ti may be attributed to its different segregation behavior on the grain boundaries. Boron in Co3Ti does not segregate on the grain boundaries and can not effectively reduce the hydrogen diffusivity along the grain boundaries.
The moisture-induced environmental embrittlement of Co3Ti alloy can be completely suppressed by the addition of Fe. It is proved by Auger that this suppression effect is due to
its obvious reduction of the kinetics of the surface reaction with water vapor.
Supported by the National Natural Science Foundation of China (Grant No.59895157,59081415,59371002,59771007) 相似文献
13.
硼对金属间化合物Ni_3Fe氢气诱发环境氢脆的影响(英文) 总被引：1，自引：0，他引：1
In this paper the tensile properties of both ordered and disordered Ni-24Fe and Ni-24Fe-0.03%B(wt%)alloys in gaseous hydrogen was investigated.The result shows that the ductility of the disordered Ni_3Fe is significantly larger than that of ordered material in gaseous hydrogen.However,the ductility of ordered Ni3Fe doped with 0.03%B is nearly the same as that of disordered one indicating the obvious suppressing effect of boron on the H_2-induced embrittlement.Based on the segregation behavior of boron in Ni_3Al,it is proposed that the suppressing effect of boron in Ni_3Fe on the H_2-induced embrittlement is attributed to the segregation of boron on grain boundaries,thereby reducing the hydrogen diffusivity along the grain boundaries. 相似文献
14.
研究了溴化十六烷基吡啶存在下硫酸铵—碘化钾—结晶紫体系浮选分离铋的行为及其与常见离子分离的条件.结果表明,在O.5mL溴化十六烷基吡啶(10g/L)存在下,当固体(NH_4)_2SO_4、碘化钾溶液(0.1mol/L)和结晶紫溶液(0.001mol/L)的用量分别为1.0g、1.0mL、1. 0mL时,控制pH值为7.0,Bi~(3+)可被该体系浮选,而常见离子Zn~(2+)、Fe~(2+)、Co~(2+)、Ni~(2+)、Al~(3+)不被浮选,据此实现了Bi~(3+)与这些离子的定量分离,对合成水样进行了定量浮选分离测定,结果满意。 相似文献
15.
In this paper the tensile properties of both ordered and disordered Ni-24Fe and Ni-24Fe-0.03%B （wt%） alloys in gaseous hydrogen was investigated. The result shows that the ductility of the disordered Ni3Fe is significantly larger than that of ordered material in gaseous hydrogen. However, the ductility of ordered Ni3Fe doped with 0.03%B is nearly the same as that of disordered one indicating the obvious suppressing effect of boron on the H2-induced embrittlement. Based on the segregation behavior of boron in Ni3A1, it is proposed that the suppressing effect of boron in Ni3Fe on the H2-induced embrittlement is attributed to the segregation of boron on grain boundaries, thereby reducing the hydrogen diffusivity along the grain boundaries. 相似文献
16.
The Mg-based hydrogen storage alloys Mg2Ni, Mg2Ni0.7Fe0.3 and Mgl.7Alo.3Ni were successfully synthesized by a two-step process （sintering and ball milling）. The crystal structure and microstructure were examined by X-ray diffraction, Scanning Electron Microscope and Malvern particle size analyzer. New phase appears in the tripe alloys doped with A1 and Fe, and the particle size ranges from 3μm to 5 μm. The electrochemical performance studies indicate that the partial substitution of AI for Mg, and Fe for Ni significantly improve the cycle life, reversibility of hydrogen absorption and desorption. The diffusion process is the control step in the electrode reaction of hydrogen storage alloys. 相似文献
17.
WANG Xiu-li TU Jiang-ping CHEN Chang-pin ZHANG Xiao-bin ZHAO Xin-bing 《Journal of Zhejiang University. Science. B》2005,(3)
Mg2Ni0.8Cr0.2-x wt.% CoO/Al2O3 (x=0.5, 1, 2 and 3) composites were prepared by mechanically milling sintered Mg2Ni0.8Cr0.2 alloy and CoO/Al2O3 compound for 45 h. The addition of CoO/Al2O3 compound resulted in the good kinetics properties of hydriding/dehydriding reaction of the composites. The composite with 1.0 wt.% CoO/Al2O3 catalyst could reach the maximum hydrogen absorption capacity (2.9 wt.%) within 5 min at 393 K under H2 pressure of 4 MPa, and can desorb rapidly at 493 K. The decomposition and synthesis of hydrogen molecule on Mg2Ni0.8Cr0.2 alloy surface was promoted by addition of CoO/Al2O3 catalyst. In addition, the formation of metallic Ni particles, strain and defects during the ball milling process also resulted in the improved hydrogenation performance of Mg2Ni-based alloys. 相似文献
18.
Wang XL Tu JP Chen CP Zhang XB Zhao XB 《Journal of Zhejiang University. Science. B》2005,6(3):208-212
INTRODUCTION Mg-based alloys are considered as potentialcandidates for hydrogen storage materials because oftheir large hydrogen capacity (Reilly and Wiswall,1968; Pedersen and Larsen, 1993). However, asMg-based alloys desorb hydrogen at temperatureshigher than 600 K, they are not applicable to practicaluse. Many researches have studied to improve hy-driding/dehydriding kinetics and to lower the workingtemperature (Wang et al., 2002; Tsushio et al., 1998;Spassov and K?ster, 1998; Orim… 相似文献
19.
Researchershavebecomeincreasinglyinterestedinironaluminideintermetallics (includingFe3AlandFeAl)since 1970sinviewofthecombinationoflowcost,lowerdensity ,remarkableresistancetoerosion ,sulfidizingandoxidizingathightemperature .However ,industrialap plicationofthesealloyshasbeenverylimitedduetotheirpoorductilityandfracturetoughnessatroomtemperatureaswellastheirdifficultyinshaping[1] .Somestudieshaveindicatedthatcoatingstructuralmaterialswithironaluminidesbyusingthermalsprayingwillnotonlysolveth… 相似文献