Non-isothermal decomposition kinetics and lifetime ofTb2(O-MBA)6(PHEN)2

The thermal decomposition of Tb2(O-MBA)6(PHEN)2 (O-MBA: o-methylbenzoate; PHEN: 1,10-phenanthroline)and its kinetics were studied under the non-isothermal condition by thermogravimetry-derivafive thermogravimetry (TG-DTG) techniques. Kinetic parameters were obtained from analysis of TG-DTG curves by the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as dα/dt = Aexp(-E/RT) @ 3(1 - α)2/3. The lifetime equation at mass loss of 10% was deduced as lnτ= -28.7429 + 19797.795/T by isothermal thermogravimetric analysis.     

水合草酸镧的热分解动力学(英文)

以PEG20000为表面活性剂在撞击流反应器中制备La2O3超细粉体的前驱体十水草酸镧(La2(C2O4)3.10H2O)。在室温至900°C下研究La2(C2O4)3.10H2O的热分解过程,通过FTIR和DSC-TG对其反应中间物及最终固体产物进行分析。结果表明,该热分解过程由5个连续的反应阶段组成。采用Flynn-Wall-Ozawa(FWO)和Kissinger-Akahira-Sunose(KAS)法对活化能E进行求取,结果显示E值随着α的变化而变化,说明草酸镧的分解为复杂的热分解过程。采用多元非线性回归分析法对动力学方程和相关动力学参数进行拟合,得到动力学模型为G(α)=[1-(1+α)1/3]2。采用该动力学模型求得的活化能平均值与采用FWO法和KAS法计算而得的活化能平均值十分接近,其拟合曲线与样品的热重分析曲线吻合。     

Kinetics of Thermal Decomposition for Complex [Zn(C_(16)H_(18)FN_3O_3)_2(NO_3)_2]·2H_2O

1 ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｒｅｃｅｎｔｙｅａｒｓ ,ｔｈｅｉｎｔｅｒａｃｔｉｏｎｂｅｔｗｅｅｎｎｏｒｆｌｏｘａｃｉｎａｎｄｃｅｒｔａｉｎｍｅｔａｌｌｉｃｉｏｎｓｈａｓｂｅｅｎｖａｌｕｅｄｗｉｄｅｌｙ[1～ 4].Ｂｕｔｔｈｅｎｏｎ ｉｓｏｔｈｅｒｍａｌｋｉｎｅｔｉｃｓｏｆ[Ｚｎ(ＮＦＡ) 2 (ＮＯ3) 2 ]·2Ｈ2 Ｏｔｈｅｒｍａｌｄｅｃｏｍ ｐｏｓｉｔｉｏｎｈａｓｒａｒｅｌｙｂｅｅｎｓｔｕｄｉｅｄ .Ｉｎｔｈｉｓｐａｐｅｒ ,ｗｅｄｉｓｃｕｓｓｅｄｉｔｓｔｈｅｒｍａｌｄｅｃｏｍｐｏｓｉ ｔｉｏｎｂｅｈａｖｉｏｒｂｙ…     

Preparation and spectroscopic, and thermal decomposition kinetic studies of europium(Ⅲ) complex [Eu(HNBD)3] (HNBD: 1-(6-hydroxy-1-naphthyl)-1,3-butanedione)

The complex of Eu(Ⅲ) with 1-(6-hydroxy-1-naphthyl)-1,3-butanedione (HNBD) was prepared for the first time and characterized by elemental analysis, IR, UV, fluorescence spectrum, and DTA-TG-DTG techniques. The IR and UV-visible spectra showed that Eu(Ⅲ) ion was coordinated to the HNBD ligand. The fluorescence spectrum showed the presence of Eu3+ characteristic emission. The TG-DTA-DTG curves showed that the thermal decomposition of the anhydrous complex was a two-stage process and the final residue was Eu2O3. The thermal decomposition kinetic parameters of the complex were evaluated from TG-DTG data by using three kinds of integral methods (Coat-Redfern equation, Horowitz and Metzger equation, Madhusudanan-Krishnan-Ninan equation). The kinetic parameters of the first stage are E* = 164.02 kJ·mol-1, A = 1.31 × 1015 s-1, △S*= 42.27 J·K-1·mol-1, △H*= 159.51 kJ·mol-1, △G*= 136.54 kJ·mol-1, and n = 3.1, those of the second stage are E*= 128.52 kJ·mol-1, A = 1.44 × 106 s-1, △S*= - 136.89 J·K-1·mol-1,△H*= 120.41 kJ·mol-1, △G*=283.85 kJ·mol-1, and n = 1.1.     

Kinetics Study on the Thermal Decomposition of Europium p-methyl-benzoate Complex with 1,10-penanthroline under Non-isothermal Con-ditions

The special strUcture and iflteresting luminescent character of Eu(lll) complex made it veryimportant in applied researches as well as in theoretical Studies. The cryStal stricture and luminescence spectrum of europium p-methylbenzoate complex with l, 10-penanthroline were reported [l]. Its non-isothermal kinetics and thermal decomposition mechanism, however, hasrarely been studied. In the paped, the thermal decomposition behavior of europium p-methylbenzoate complex with l, 10-penanthroline…     

有机大阳离子与HnXW12O40·nH2O（X=B，Si，P）多金属氧酸盐的合成及热行为

合成了3种新的多金属氧酸盐(CTMA)5BW12O40·8H2O,(CTMA)4SiW12O40·3H2O,(CTMA)3PW12O40·2H2O,利用元素分析、IR光谱和TG-DTA技术对其进行了表征.IR光谱表明这些化合物不仅含有Keggin型结构,而且存在有机大阳离子的特征吸收峰;TG-DTA曲线显示它们的热行为是一个多步分解过程,首先这些化合物在大约269℃以下脱去水分子,然后它们的无水多金属氧酸盐经历了两步或3步的分解过程,分别脱去CTMA分子及其碎片,并伴随Keggin型结构的塌陷.通过XRD和IR光谱确证其最终分解产物是一个含有WO3与B2O3,SiO2或P2O5的混合物.同时还提出了这些化合物可能的热分解过程.     

Non-isothermal kinetics of the first-stage decomposition reaction of the complex of samarium p-methoxybenzoate with 1,10-phenanthroline

The complex of [Sm(p-MOBA)3phen]2 (p-MOBA, p-methoxybenzoate; phen, 1,10-phenanthroline) was pre- pared and characterized by elemental analysis, IR, and UV spectroscopy. The thermal decomposition of the [Sm(p-MOBA)3phen]2 complex and its kinetics were studied under a static air atmosphere by TG-DTG methods. The in- termediate and residue for each decomposition stage were identified from the TG curve. The kinetic parameters and mecha- nisms of the first decomposition stage were obtained from the analysis of the TG-DTG curves by a new method of process- ing the data of thermal analysis kinetics. The lifetime equation at a mass loss of 10% was deduced as lnτ = – 30.6795 21034.56/T by isothermal thermogravimetric analysis.     

Thermal Decomposition Kinetics of Ni(Ⅱ) Complex with Norfloxacin

１ＩｎｔｒｏｄｕｃｔｉｏｎＮｏｒｆｌｏｘａｃｉｎｂｅｌｏｎｇｓｔｏｔｈｅｃｏｍｐｏｕｎｄｏｆｔｈｅｓｅｒｉｅｓｏｆｃａｒｂｏｓｔｙｒｉｌｃｏｎｔａｉｎｉｎｇｆｌｕｏｒｉｎｅ．Ｉｔｉｓａｂｒｏａｄｓｐｅｃｔｒｕｍａｎｔｉｍｉｃｒｏｂｉａｌ，ａｎｄ...     

Mechanism and Kinetic Parameters of Thermal Decomposition of Cobalt Dichloride Hexahydrate

1 ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｃｏｂａｌｔｄｉｃｈｌｏｒｉｄｅｈｅｘａｈｙｄｒａｔｅｉｓｗｉｄｅｌｙｕｓｅｄａｓｏｉｌｖａｒｎｉｓｈｄｅｓｉｃｃａｎｔ ,ａｍ ｍｏｎｉａａｂｓｏｒｂｅｒ ,ｇａｓｓｈｉｅｌｄ ,ｗｅｔａｎｄｄｒｙｉｎ ｄｉｃａｔｏｒｓ ,ｂａｒｏｍｅｔｅｒ ,ｃｅｒａｍｉｃｔｉｎｔａｇｅａｇｅｎｔ ,ｋｉｎｄｓｏｆｃｒｙｓｔａｌｓａｎｄｍｅｄｉｃａｌａｇｅｎｔｓａｎｄｓｏｏｎ .ＴｈｅｋｉｎｅｔｉｃｓｏｆｔｈｅｒｍａｌｄｅｃｏｍｐｏｓｉｔｉｏｎｏｆＣｏＣｌ2 ·6Ｈ2 Ｏｈａｓｂｅｅｎｓｔｕｄｉ…     

纳米Eu0.12Y1.78La0.10O3-δ荧光粉的合成动力学

利用不同升温速率的差热-热重分析(DTA-TG)研究纳米Eu0.12Y1.78La0.10O3-δ荧光粉的合成动力学。研究表明,纳米Eu0.12Y1.78La0.10O3-δ荧光粉的前驱体为六方相Y(OH)3,利用Doyle-Ozawa法和Kissinger法计算得到前驱体2个分解阶段的表观活化能平均值分别为699.40、362.81kJ.mol-1。用Kissinger法确定反应级数和频率因子,确定纳米Eu0.12Y1.78La0.10O3-δ荧光粉2个合成阶段的反应速率方程分别为dα/dt=1.94×1046e-84120/T(1-α)1.17;dα/dt=5.89×1020e-43640/T(1-α)1.14。     

Thermal decomposition kinetics and lifetime of the complex of Tb2（BA）6（PHEN）2

The thermal behavior of Tb2(BA)6(PHEN)2 (BA: benzoate, and PHEN: 1,10-phenanthroline) in a static air atmospbere was investigated by TG-DTG, SEM and IR techniques. By the kinetic method of processing thermal analysis data put forward by Malek et al., it is defined that the kinetic model for the first-step thermal decomposition is SB(m, n). The activation energy E for this step reaction is 99.07 kJ/mol, the entropy of activation ΔS^≠ is -84.72 J/mol, the enthalpy of activation ΔH^≠ is 94.26 kJ/mol, the free energy of activation ΔG^≠ is 144.77 kJ/mol and the pre-exponential factor lnA is 20.93.The lifetime equation at mass-loss of 10% was deduced as lnτ = -29.0312 19760.83/T by isothermal thermogravimetric analysis.     

纳米亚铬酸镍的制备及其催化特性

以硝酸铬和硝酸镍为原料,采用溶胶-凝胶法制备了纳米Ni Cr2O4,并用XRD和SEM对纳米亚铬酸镍(nano-NiCr_2O_4)的微观结构进行了表征。同时,采用TG-DTG研究了nano-NiCr_2O_4对六硝基六氮杂异伍兹烷(CL-20)和高氯酸铵(AP)热分解的催化作用,用Kissinger法、Ozawa法计算了非等温动力学参数,发现nano-NiCr_2O_4使CL-20和AP的热分解峰温降低,热分解表观活化能减小。     

Preparation and Conductivity of Triheteropoly Tungstozincoaluminic Acid

Heteropoly acids (HPA) have been widelyused as e1ectrochroAnc and conducting materi-als, new modified electrodes, comPonents inconversion of solar energy, new materials foroxidation catalysis, cormsion resistant coatings,dyes or pigments, sorbents of gases, and cationexchangers etc. according to their unmatchedmolecular and electronic simctural versatility[l--4]. Because of their high-proton conductivi-ties, they are of special interest as new materi-a1s. There are two kinds of protons in th…     

The effects of long-term air exposure on the stability of lamellar TiAl alloys

The thermal stability of fine-grained and coarse-grained lamellar TiAl alloys was studied at 700°C in air. Both α₂ and γ lamellae were altered markedly after 1000- and 3000-h exposure. Three types of decomposition were found: (a) parallel decomposition of coarse α₂ into bunches of very fine α₂+γ lamellae, (b) perpendicular decomposition of fine γ (or γ+α₂) lamellae into short-ranged γ domains or (γ+α₂) grains and (c) perpendicular decomposition of fine α₂ lamellae into short-ranged α₂/γ grains. All three types are still at an intermediate stage after 3000-h exposure and neither break-up of lamellae nor globularisation of segments was observed. The thermal stability of microstructural constituents in increasing order was found to be: thick α₂, thin α₂, thin γ, and thick γ lamellae. Tensile properties were affected by these changes and the extent was found to vary from alloy to alloy.     

低电阻率Si—C—O纤维的制备——先驱体聚合物的热裂解

通过IR,TG及XRD等手段对聚二甲基硅烷（PDMS）与聚氯乙烯（PVC）共裂解合成制备的纤维先驱体（PC－P4,PC－P50）裂解进行了研究。结果表明,在初始裂解队伍,主要为小分子硅烷逸出,PC－P5发生－Si-H和－Si-CH3的脱甲烷、脱氢反应而导致交联程度的增加;而在PC－P50中,除了发生上述反应外,还存在分子内和分子间稠环芳烃结构的脱氢缩率。随裂解温度进一步的提高,PC－P5表面为脱氢,脱甲烷的无机化过程,裂解产物从有机物转变为存在部分微晶的无机结构,裂解温度继续提高后,Si-C-O玻璃相和富余碳反应使SiC晶粒尺寸增加,并伴有CO气体的放出。     

Synthesis and reaction behavior of calcium silicate hydrate in basic system

1　INTRODUCTIONIt skeytoseparatealuminafromsilicainaluminaproductionbyBayerorsinteringprocess .Whethersilicachangestosodiumaluminosilicatehydrateorhydro garnet(bothtitleddesilicationproduct,DSP) ,bothcontainso daoralumina .IfDSPisdischargedoutdirectly ,alargeamountofsodaandaluminawillbewasted ,meanwhiledischargedDSPwillresultinheavyenvironmentalpollu tion .InpresentitcostsalottorecoveraluminaandsodafromDSPbysinteringprocess[1] .Soitisurgenttodevel opnewhydro processtechnologytorecove…     

α-Al2 O3微粒对铸造Al-Si合金微弧氧化膜耐蚀性的影响

目的通过共生沉积技术将α-Al2O3微粒引入到铸造Al-Si合金微弧氧化膜中,并研究其对膜层耐蚀性的影响。方法利用SEM和XRD分析α-Al2O3微粒对微弧氧化膜微观结构及成分的影响。通过极化曲线、交流阻抗谱及中性盐雾试验评价膜层的耐蚀性。结果α-Al2O3微粒复合改变了微弧氧化膜的组成及结构。微弧氧化膜呈双层结构,表面存在大量微孔,主要组成为γ-Al2O3;加入α-Al2O3微粒后,微弧氧化复合膜的表面微孔大幅减少,致密度提高,且膜层中α-Al2O3相增多。此外,α-Al2O3微粒复合改善了微弧氧化膜的耐蚀性。微弧氧化膜在质量分数为3.5%的Na Cl溶液中的自腐蚀电流密度约为1.476×10-5A/cm2,多孔层电阻Rp及阻挡层电阻Rb分别为0.259 kΩ·cm2及69.18 kΩ·cm2,耐盐雾试验时间为1200 h。加入α-Al2O3微粒后,微弧氧化复合膜的自腐蚀电流密度仅为微弧氧化膜层的28%,Rp大幅增加至274.5 kΩ·cm2,且Rb也上升了一个数量级,耐盐雾试验时间可达1440 h。结论α-Al2O3微粒的引入可以大幅提高铸造Al-Si合金微弧氧化膜的耐蚀性。     

Magnetic transitions and magnetocaloric effect in MnAs0.9P0.1

The compound MnAs0.9P0.1 exhibits a multistep magnetic order-order transition from a helimagnetic γ-phase with Hα-type magnetic order to a ferromagnetic β-phase at 80 K and then to a helimagnetic α-phase at 203 K. The γ-β transition exhibits the characteristics of a first-order transition with a thermal hysteresis as large as 6 K, while the β-α transition is of second order with a thermal hysteresis smaller than 2 K and without magnetic hysteresis. With these two successive helimagnetism-related transitions, magnetic-entropy changes of -2.1 J/(kg·K) at 203 K for a field change from 0 to 5 T and 0.1 J/(kg·K) at 83 K for a field change from 0 to 1 T are obtained. Investigation of the magnetocaloric effect associated with a transition from Hα-type magnetic order to FM order may open a new route to explore candidates for magnetic refrigeration.     

Thermal Decomposition of Massive Phase to Fine Lamellar α/β in Ti–6Al–4V Additively Manufactured Alloy by Directed Energy Deposition

Metals and Materials International - The occurrence of a massive phase (αm) transformation and a thermal decomposition of an αm to fine lamellar α/β with an α lamellar...     

Synthesis of ZSM-5 zeolite membranes without organic templates using a varying-concentration technique

Template-free nanosized ZSM-5 seeds with an average size of 15 nm were prepared from a synthesis solution with the composition 12Na2O:100SiO2:2Al2O3:2500H2O. By the use of these seeds, thin ZSM-5 zeolite membranes were prepared on the outer surface of a porous α-alumina tube with a pore size of 2 μm in a gel system by varying-concentration synthesis with organic-free template. The first composition synthesis sol-gel was the same as seeds of molar composition and the second one was 12Na2O:100SiO2:2Al2O3:5000H2O at 180 ℃ for 10 h, respectively. XRD shows that the film consists of well-crystallized ZSM-5 zeolite. SEM investigation indicats that the zeolite films on the supports are defect free and the film thickness is approximately 8 μm. The permeances for H2, N2, CH4 and CO2 are 8.94×10-7 , 3.27×10-7 , 3.9×10-7 , 3.14×10-7 and 0.874×10-7 mol·m2·s-1·Pa-1 , respectively. The ideal selectivity of membrane at room temperature for H2/CO2, H2/N2, H2/CH4 are 2.84, 2.73 and 2.29, respectively.