共查询到20条相似文献,搜索用时 15 毫秒
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Wei-Jen Shih Moo-Chin Wang Kuo-Ming Chang Cheng-Li Wang Szu-Hao Wang Wang-Long Li Hong-Hsin Huang 《Metallurgical and Materials Transactions A》2010,41(13):3509-3516
The effect of heat treatment on the calcium phosphate deposited on Ti-6Al-4V substrate using an electrolytic process is investigated.
The calcium phosphate was deposited in a 0.04 M Ca(H2PO4)2·H2O (MCPM) solution on a Ti-6Al-4V substrate at 333 K (60 °C), 10 V, and 80 Torr for 1 hour, and calcined at various temperatures
for 4 hours. The X-ray diffraction (XRD) results demonstrate that the phases are dicalcium phosphate (CaHPO4, DCPD) and hydroxyapatile [Ca(PO4)6 (OH)2, HAP] for the as-deposited samples. When the deposited sample was calcined at 873 K (600 °C) for 4 hours, the XRD results
show that the transformation of DCPD to HAP occurs. Moreover, HAP converts to β-TCP, CPP, and CaO. For the sample calcined at 1073 K (800 °C) for 4 hours, the scanning electron microscopy (SEM) micrograph
reveals that the crack of the calcined sample propagates with a width of about 3 μm. This result is due to HAP becoming decomposed and converting to β-TCP, CPP, CaO, and H2O. The vaporization of H2O within the calcined sample promotes the crack propagation and growth. 相似文献
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S. RAGHAVAN 《Mineral Processing and Extractive Metallurgy Review》2013,34(1):221-230
Abstract A knowledge of the thermodynamic stabilities of the lanthanum tungstates measured as the Gibbs energies of formation from the free oxides is important as lanthanum is used as a powerful desulphurizing agent and tungsten as a special alloying element in the production of clean steels and special steels. These data will also be useful as the system La2O3 WO3 can be a model since it exhibits many compounds between the end members. Excepting one EMF work, no information is available in the literature on the thermodynamics of this system. This system exhibits the compounds 5 La2O3·22 WO3, La2 O3 · 3 WO3, La2O · 2 WO3, 7 La2O3 · 8 WO3,La2O · WO3, 3 La2O3 · 2 WO3 and 5 La2O3 · 2 WO3. The compounds were prepared from reagent grade free oxides by solid state sintering at high temperature followed by X-ray diffraction. The standard Gibbs energies of formation of the compounds from the free oxides were determined by operating the following galvanic cells with calcium fluoride as solid electrolyte. O2(g), Pt/ La2O3 · LaOF// CaF2/ / 5 La2O3 · 22 WO3, WO3, LaOF/Pt, O2(g) O2(g), Pt/La2O3 · LaOF//CaF2//5 La2O3 · 22 WO3, La2O3 · 3 WO3, LaOF/Pt, O2(g) O2(g), Pt/La2O3 · LaOF//CaF2// La2O3 · 3 WO3, La2O3 · 2 WO3 LaOF/Pt, O2(g) O2(g), Pt/La2O3 · LaOF//CaF2// La2O3 · 2 WO3, 7 La2O3 · 8 WO3, LaOF/Pt, O2(g) O2(g), Pt/La2O3 · LaOF//CaF2//La2O3 · WO3, 3La2O3 · 2 WO3 LaOF/Pt, O2(g) O2(g), Pt/La2O3 · LaOF//CaF2//3 La2O3 · 2 WO3, 5La2O3 · 2 WO3 LaOF/Pt, O2(g) O2(g), Pt/ La2O3 LaOF// CaF2/ / 3 La2O32 WO3, La2O3, 2 WO3 LaOF/Pt, O2(g) Stable, reproducible EMFs were obtained in the temperature range 1123 to 1273 K. The net cell reactions are respectively as follows: 5 La2O3 + 22 WO3 = 5 La2O3 · 22 WO3 7 La2O3 + 3 (5 La2O3 · 22 WO3) = 22 (La2O3 · 3 WO3) La2O3 + 2 (La2O3 · 3 WO3) = 3 (La2O3 · 2 WO3) 3 La2O3 + 4 (La2O3) = 7 La2O3 · 8 WO3 La2O3 + 7 La2O3 · 8 WO3 = 8 (La2O3 · WO3) La2O3 + 2 (La2O3 · WO3) = 3 La2O3 · 2 WO3 2 La2O3 + 3 La2O3 · 2 WO3 = 5 La2O3 · 2 WO3 The standard Gibbs energies of formation of the different lanthanum tungstates are then calculated by appropriately combining from the above cell reactions and their Gibbs energy changes obtained from the experimental EMF data. The present data are discussed in the light of EMF data reported in the literature for WO3-rich compounds in the system. 相似文献
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建立了电感耦合等离子体质谱法测定钢铁中痕量镁和钙元素含量的分析方法。在优化的仪器工作条件下,采用内标法与加入校正法相结合,在补偿基体效应的同时.提高了测定结果的稳定性。该方法加标回收率为90.0%~110.0%,相对标准偏差小于10.0%.该方法准确、快速,满足冶金行业对钢铁中痕量镁和钙元素的测试需要。 相似文献
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Woong-Hee Han Takashi Nagai Masao Miyake Masafumi Maeda 《Metallurgical and Materials Transactions B》2009,40(5):656-661
The vapor pressures of Sc, La, and Ce were determined by multi-Knudsen cell mass spectrometry with ionized cross sections
as described in the literature. The vapor pressure of Sc at temperatures from 1373 K to 1573 K was measured using Cu as a
reference material, and those of La and Ce from 1473 K to 1573 K were measured using Y as a reference material. From the measured
vapor pressures, the Gibbs energy of formation of each gaseous element was derived. 相似文献
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ICP-MS法测定八氧化三铀中钼的测量结果的不确定度评定 总被引:1,自引:0,他引:1
介绍了ICP—MS法测定八氧化三铀中钼质量分数的测量不确定度的影响因素。对各不确定度分量进行了分析和计算。八氧化三铀中钼质量分数为29.1μg/g时,测量结果的扩展不确定度为4.2μg/g。 相似文献
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L. Bencze D. D. Raj D. Kath L. Singheiser K. Hilpert W. A. Oates J. Herrmann 《Metallurgical and Materials Transactions A》2003,34(11):2409-2419
The vaporization of Fe-Al alloys has been investigated in the temperature range of 1140 to 1600 K by Knudsen effusion mass
spectrometry. Eleven different compositions were examined in the composition range between 30 and 51 at. pct Al, mostly in
the B2 region of the phase diagram. The partial pressures and thermodynamic activities of both Fe and Al were evaluated: directly
from the measured ion intensities for a component in both the alloy and the pure element, I
M
+
/I
M
+0
, and also from the ion-intensity ratios of the alloy components, I
Al
+
/I
Fe
+
, by means of a Gibbs-Duhem integration. Reliable partial and integral molar enthalpies and entropies of mixing have been
obtained by mass spectrometry for this system for the first time. Nearly temperature-independent integral enthalpies and entropies
of mixing over the wide temperature range investigated were found, with the mixing entropies being large and negative. 相似文献
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Takashi Nagai Yusuke Tanaka Masafumi Maeda 《Metallurgical and Materials Transactions B》2011,42(4):685-691
The thermodynamic properties of the CaO-P2O5 system are important to develop an effective refining process in the iron and steel industry. In this study, the thermodynamic
properties of (CaO)2P2O5 were investigated because the properties are necessary to develop a new dephosphorization process. The vapor of gaseous phosphorus
and phosphorus oxide in equilibrium with a mixture of (CaO)2P2O5 and (CaO)3P2O5 at 1373 K to 1498 K (1100 °C to 1225 °C) were detected directly as an ion current by double Knudsen cell mass spectrometry.
Comparing the ion currents with those from a mixture of Al2O3P2O5 and Al2O3, which is used as a reference mixture in this study, the Gibbs energy change of the following reaction was calculated:
2\textCaO( \texts ) + \text P2 ( \textg ) + \frac52\textO2 ( \textg ) = ( \textCaO )2 \textP2 \textO5 ( \texts ) 2{\text{CaO}}\left( {\text{s}} \right) \, + {\text{ P}}_{2} \left( {\text{g}} \right) \, + \frac{5}{2}{\text{O}}_{2} \, \left( {\text{g}} \right) = \left( {\text{CaO}} \right)_{2} {\text{P}}_{2} {\text{O}}_{5} \left( {\text{s}} \right) 相似文献
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Hydrogen embrittlement has been observed since high‐strength steels have been produced in the nineteen thirties 1 . Several different analytical methods have been developed to quantify the total and diffusible hydrogen in steel, but many aspects of hydrogen determination are still to be explored. Purely quantitative determination of hydrogen is not sufficient to fully characterize the steel regarding its resistance against embrittlement. Thermal Desorption Mass Spectrometry (TDMS) allows the investigation of hydrogen absorption and desorption mechanisms to characterize hydrogen traps in different kinds of steel microstructures. This provides valuable information for the development of new materials with a higher resistance against hydrogen embrittlement. Additionally, TDMS allows the quantitative determination of very small concentrations of hydrogen (<0.1 µg/g). Such low detection limits cannot be reached with other methods. Due to time‐consuming analysis and a rather complex construction, TDMS is usually not applied for hydrogen determination in German steel mills. The present work describes the development of a thermal desorption spectrometer at ThyssenKrupp Steel Europe AG by adapting a compact quadrupole mass spectrometer to a commercially available hot solid extraction analyzer, which has proven to be a simple and efficient solution for the determination of diffusible hydrogen in steel. 相似文献
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钢液钙处理的热力学分析 总被引:13,自引:5,他引:8
通过热力学计算分析了铝镇静钢钙处理时Fe-Al-Ca-O-S系中的各种平衡曲线。分析了1873K时在各种平衡态下的Al—O、Ca-Al、S-Al、S-Ca平衡曲线,并分析了在不同平衡状态下温度对平衡曲线的影响。得出了为避免生成固态铝酸钙、CaS理论上应满足的条件。 相似文献
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采用X射线荧光光谱法测定石灰石中Ca O含量,应用统计学理论对其测量结果的不确定度来源进行分析,并对各不确定度分量进行评定,计算合成标准不确定度和扩展不确定度,完成不确定度报告,为提高检测工作的科学性和准确性提供了保证。 相似文献
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P. R. VASUDEVA RAO 《Mineral Processing and Extractive Metallurgy Review》2013,34(3-4):309-331
Abstract Tri-n-Butyl Phosphate has been found to be an extractant-par-excellence for nuclear fuel reprocessing. It has a unique combination of physical and chemical proerties and is commercially available at relatively low cost. However, the other homologues of TBP-with branched alkyl chains as well as linear alkyl chains-do possess advantages for specific applications that merit attention. Thus, a relative comparison of the extraction properties of the trialkyl phosphates is rewarding, both from a fundamental as well as technological point of view. The present review attempts to survey the data reported and the understanding generated on the extraction of actinides by trialkyl phosphates, with an emphasis on the elements U, Th and Pu, taking into account their importance derived from their primary role in the nuclear fuel cycles. While reviewing the data, emphasis is placed on data measured for extraction by 1.09 M solution of the extrac-tant, from nitric acid medium. 相似文献
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采用电感耦合等离子质谱法测定钽粉中的杂质,对仪器的工作条件、样品制备、样品分析模式、基体浓度、精密度、回收率等进行了较为系统的研究.结果表明,该检测方法准确可靠、精密度高,钽粉中各杂质元素的相对标准偏差为1.64%~15.99%,加标回收率为92%~128%,可满足钽粉的分析要求. 相似文献
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提出了一个用火焰原子吸收分光光度法测定铁矿中氧化钙、氧化镁的方法。研究讨论了酸度、干扰离子、工作条件等因素的影响。分析中。以HNO3—HF—HCLO4混合酸分解样品。以SrCL2作为钙、镁的释放剂,用工作曲线法测定。方法简便、快速、准确。应用于铁矿样品的测定,结果令人满意。 相似文献
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通过对CaO-Al2O3、CaO-Al2O3-SiO2、CaO-SiO2、Al2O3-SiO2系的热力学分析,探讨铝土矿低钙石灰烧结过程中的热力学反应规律。结果表明,在烧结温度范围内(1 200~1 400℃),生成CaO.Al2O3和2CaO.Al2O3.SiO2的反应能发生,Al2O3可与SiO2生成Al2O3.SiO2。 相似文献
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原子吸收光谱法测定锡精矿中的氧化钙及氧化镁 总被引:1,自引:1,他引:0
建立了火焰原子吸收光谱法测定锡精矿中CaO及MgO量的方法。所建立的方法CaO及MgO的特征浓度分别为0.087μg/mL,0.0034μg/mL;检出限分别为0.022μg/mL,0.0028μg/mL;标准曲线的线性相关系数均大于0.999;测定范围分别为0.050%-7.50%,0.010%-2.00%;对11个代表样及2个标样进行考察,精密度分别为0.7%-11.1%,2.5%~10.5%;样品加标回收率分别为91.5%~102.7%,98.6%~102.7%。 相似文献
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电感耦合等离子体质谱法(ICP-MS)具有检测限低,干扰少等优点,在痕量稀土的测定中应用越来越广。综合介绍了近年来各种环境水质、食品、动植物组织、土壤及地质样品、高纯稀土产品中痕量稀土的ICP-MS法测定最新研究进展。 相似文献
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