B_2O_3和CaF_2对C_3S-C_(2.75)B_(1.25)A_3-C_2S-C_3A水泥熟料矿物体系力学性能影响

研究了B2O3和CaF2对C3S-C2.75B1.25A3S珚-C2S-C3A熟料矿物体系的组成、结构与力学性能的影响。研究结果表明:在该熟料体系中C3S,C2.75B1.25A3S珔,C2S和C3A的适宜含量分别为50%,10%,25%和15%,B2O3和CaF2的适宜掺量为2%和1.5%。在最佳组成和制备工艺条件下,合成的阿利特-硫铝酸钡钙水泥的1d,3d和28d抗压强度分别达到18MPa,48MPa和95MPa以上,展现了良好的早期力学性能。同时,掺加CaF2能有效降低熟料中游离氧化钙的含量,促进阿利特在低温条件下形成。利用SEM-EDS,XRD等测试手段对熟料的组成、结构及性能进行了分析。     

CaF2 对贝利特-硫铝酸钡钙水泥性能的影响

采用化学纯试剂为原料,将硫铝酸钡钙矿物引入到贝利特熟料矿物体系中,合成了贝利特-硫铝酸钡钙水泥.本文主要研究了 CaF2 对熟料矿物组成和水泥性能的影响.研究结果表明,CaF2 能够加快熟料中f-CaO的吸收,促进C2.75B1.25A3(S)矿物形成,提高水泥的早期强度.当CaF2 在熟料中的掺人量为0.6%时,贝利特.硫铝酸钡钙水泥的 3d 和 28d 抗压强度分别达到 26.8 MPa和 83.4 MPa,展现了良好的力学性能.利用 XRD,SEM-EDS 和岩相分析等测试手段分析了水泥熟料的组成和结构.     

含C_4A_3早强矿物的硅酸盐水泥熟料体系的研究

研究了在硅酸盐水泥熟料中引入C4A3的条件、生料的易烧性、适宜的煅烧温度及水泥的性能。研究结果表明,合理的矿物组成、掺入适量的石膏和助熔剂是实现C3S-C4A3共存的前提条件。通过在C3S-C4A3S-C2S-C4AF熟料体系中引入5%～20%的C4A3S,所制备的熟料体系具有良好的强度性能,其3d强度在15～30MPa,7d强度在25～40MPa,28d强度在45～65MPa之间。     

CaF2对硫铝酸钡钙矿物形成过程的影响

采用X射线衍射、扫描电镜和差热-热重分析等测试方法研究了CaF2对硫铝酸钡钙矿物2.75CaO·0.25BaO·3Al2O3·BaSO4(C2.75B1.25A3ˉS)形成过程的影响,并对高温固相反应过程中出现的物相进行了初步分析.结果表明CaF2加速了CaCO3的分解,降低了C2.75B1.25A3ˉS的形成温度.当温度低于1 300℃时,CaF2可能促进C2.75B1.25A3S的形成及结晶,并同时伴随着氟铝酸盐矿物11CaO·7A12O3·CaF2的生成.另外,CaF2对C275B1.25A3S的高温分解没有明显的影响.     

阿利特-硫铝酸钡钙水泥材料制备技术的研究

通过正交试验研究制备阿利特-硫铝酸钡钙水泥材料。结果表明：阿利特和硫铝酸钡钙矿物能够共存于同一熟料体系,这为合成阿利特一硫铝酸钡钙水泥材料奠定了重要基础;对该熟料力学性能影响程度最大的因素是矿物设计比例,其次是煅烧温度,各因素的最佳水平分别为矿物设计比例C3S：C2S：C2.75,5B1.25A3S^-=15：15：65。煅烧温度为1350℃,Fe2O3掺加量为1％,CaF2掺加量为2％;同时,在最佳水平条件下制备的熟料1d,3d和28d抗压强度分别达到51．7MPa,77．0MPa和79．5MPa,展现出良好的早期力学性能。同时利用XRD和SEM-EDS对熟料矿物组成及结构进行了分析。     

Ba在C2S-C3S矿物相中固溶机理探讨

以Ca(OH)2、SiO2、Fe2O3、Al2O3化学纯为原料,分别掺入不同质量分数的Ba(OH)2制备不同矿物相组成的熟料相,运用化学分析、XRD、SEM、水化热测试方法,研究掺Ba(OH)2后熟料相中硅酸三钙-硅酸二钙(C3S-C2S)混合相组成、晶型、新相生成的变化规律.结果表明:Ba(OH)2一定程度上削弱C3S形成,且稳定β-C2S形成效应明显,矿物相体系中α'-C2S、α-C2S量减少并转换为β-C2S,掺量大于2.5％后有新相Ba0.48 Ca1.52SiO4形成;Ba(OH)2掺入促使矿物相中C2S相明显增多,晶粒整体尺寸变小,边界变圆润;随Ba(OH)2掺量递增,熟料样的水化速率呈持续减小的趋势变化.     

含C4A3-S早强矿物的硅酸盐水泥熟料体系的研究

研究了在硅酸盐水泥熟料中引入C4A3S^-的条件、生料的易烧性、适宜的煅烧温度及水泥的性能。研究结果表明,合理的矿物组成、掺入适量的石膏和助熔剂是实现C3S-C4A3S^-共存的前提条件。通过在C3S—C4A3S^--C2S—C4AF熟料体系中引入5％-20％的C4A3S^-,所制备的熟料体系具有良好的强度性能,其3d强度在15-30MPa,7d强度在25～40MPa,28d强度在45～65MPa之间。     

MgO对硫铁铝酸钡钙矿物的合成及性能的影响

用X射线衍射、扫描电子显微镜和综合热分析等研究了MgO对硫铁铝酸钡钙矿物1.75CaO·1.25BaO·2Al2O3·Fe2O3·CaSO4(C2.75B1.25A2F S)的合成及性能的影响,并测试了水化样品的抗压强度.结果表明:适量的MgO可降低CaCO3的分解温度,当MgO掺入质量分数为1%时,C2.75B1.25A2FS矿物形成的温度最低,矿物熟料中f-CaO的质量分数最低,仅为0.22%.水化物,28 d时的抗压强度达到最高,为104.2MPa.当MgO的掺量在0.3%～1%时,熟料晶体结晶状况相对较好,晶粒细小,晶界明显,轮廓清晰.     

Q相-C2S-C4AF-C12A7系列水泥形成的研究

通过研究Q相与C2S和Q相与C4AF的共存条件,构造Q相-C2S-C4AF水泥系统,对此系统水泥形成条件进行研究.研究表明:Q相与C2S和Q相与C4AF能够共存,可以组成Q相-C2S-C4AF-C12A7水泥系统.在Q相-C2S-C4AF-C12A7水泥系统中,Q相在1270℃开始生成,随着温度的升高,Q相的生成量逐渐增大;采用V2O5对β-C2S具有较好的稳定作用.随着C4AF量的增加,Q相的量也在增加,同时,烧成温度降低.     

CaF2对阿利特-硫铝酸锶钙水泥性能的影响

将硫铝酸锶钙矿物引入到硅酸盐熟料矿物体系中,合成阿利特-硫铝酸锶钙水泥.利用XRD,SEM-EDS和岩相等测试手段研究了CaF2对阿利特-硫铝酸锶钙水泥熟料矿物组成和水泥性能的影响.结果表明,CaF2能够促进固相反应使得阿利特在较低温度下形成,有利于阿利特和硫铝酸锶钙矿物的共存.当CaF2在熟料中的掺入量为0.6%时,阿利特-硫铝酸锶钙水泥的1 d、3 d和28 d抗压强度分别达到32.8 MPa、67.7 MPa和120.4 MPa,表现出良好的力学性能.     

C3S-C12A7-H2O和C3S-C12A7-CaSO4·2H2O-H2O系统的水化及其性能研究

试验用结合水法、化学减缩法、XRD定量等物理、化学分析方法 ,研究了C1 2 A7和石膏同时存在时C3S在不同系统中的水化动力学及水化机理。结果表明C1 2 A7能够促进C3S的水化 ,尤其是对C3S早期水化有显著的促进作用 ;当有石膏存在时 ,这种促进作用更为显著。其机理是由于C1 2 A7水解放出的Al(OH) - 4 与C3S水解放出的Ca2 反应生成C3AH6 ,当有石膏存在时 ,生成钙钒石 ,从而加快了C3S的水化。研究得出了C3S在不同系统中的水化动力学方程     

Q相-C2S-C4AF-C12A7水泥作为膨胀剂的研究

采用普通硅酸盐水泥作为基体、Q相-C2S-C4AF-C12A7水泥作为膨胀剂、加入少量石膏的条件下进行试验研究。研究表明：Q相-C2S-C4AF-C12A7水泥能够作为膨胀组分,调节Q相-C2S-C4AF-C12A7水泥和SO3的量,能够得到所要求的膨胀水泥。从DTA和XRD得知,其膨胀源主要是钙矾石（AFt）,它形成的速度及数量,可以通过控制Q相-C2S-C4AF-C12A7水泥和SO3的量来实现。     

Hyperbranched azo polyurethane synthesized through A2 + B3 scheme

A hyperbranched azo polyurethane was synthesized by one-step polymerization of an A₂ type monomer diphenylmethane-4,4′-diisocyanate and a B₃ type monomer 4-(N,N′-bis(2-hydroxyethyl))amino-2′-hydroxyethoxyl-4′-nitro-azobenzene. The azo polymer was characterized by ¹H nuclear magnetic resonance (NMR), ultraviolet-visible (UV-Vis) spectrum and thermal analysis. The λ_max of the polymer in dimethylformamide (DMF) solution is 488 nm. The number average molecular weight (M_n) determined by GPC is 9,300 with a polydispersion index 1.9. The glass transition temperature (T _g) of the polymer is 131°C observed from DSC thermogram. The results show that the azo polyurethane has been successfully synthesized through this scheme. Surface-relief-gratings (SRGs) were fabricated on the polymer film after being irradiated by interference pattern of Ar⁺ laser beams for 1,000 s. The surface modulation depth and the grating space period measured by AMF are 67 and 770 nm, respectively. __________ Translated from Acta Polymerica Sinica, 2007, 1: 21–25 [译自: 高分子学报]     

Thermal Conductivity of Molten B2O3, B2O3–SiO2, Na2O–B2O3, and Na2O–SiO2 Systems

With the aid of the transient hot‐wire method, the thermal conductivity of molten B₂O₃, B₂O₃–SiO₂, Na₂O–SiO₂, and Na₂O–B₂O₃ systems was measured along with their temperature and composition. It was observed that the thermal conductivity of pure B₂O₃ increased with temperature, until about 1400 K, and then decreased subsequently. Using the MAS‐NMR, 3Q‐MAS, and Raman spectroscopy, the structure of B₂O₃ and SiO₂ in the B₂O₃–SiO₂ system was confirmed. Findings show that an addition of B₂O₃ into the pure SiO₂ system causes a significant decrease in thermal conductivity, due to the formation of boroxol rings. The thermal conductivity of the Na₂O–SiO₂ system was measured and its phonon mean free path was calculated. In addition, a positive linear relation between viscosity and thermal conductivity was observed. In the Na₂O–B₂O₃ system, it was found that a change in the relative fraction of 4‐coordinated boron has an influence on the thermal conductivity when the concentration of Na₂O is between 10 and 30 mol%, in which case the tetraborate unit is dominant.     

Wetting,densification and phase transformation of La2O3/A2O3/B2O3-based glass–ceramics

A lead-free, non-alkali La₂O₃–Al₂O₃–B₂O₃ (LAB) glass with Al₂O₃ filler had been investigated for low temperature co-firing ceramic (LTCC) application. The glass forming window and several physical properties of the LAB systems were investigated by ICP, TMA, XRD, DSC, and SEM/EDS. The results show that the densification and crystallization temperatures of LAB/Al₂O₃ were between 700 °C and 950 °C and depended greatly on the formulation. Crystalline phase LaBO₃ (LB) and LaAl₂B₃O₉ (L2A3B) crystallized starting at 825 °C and 925 °C, respectively. High degree of densification and crystallization of one glass–Al₂O₃ composition (L30A) was observed with the microstructure composed of tabular L2A3B grains interlocking with submicron Al₂O₃ and LB grains.     

BaO−B2O3 system and its mysterious member Ba3B2O6

The first systematic study of the BaO–B₂O₃ system and barium orthoborate Ba₃B₂O₆ (3BaO·B₂O₃) was reported in 1949. Thereafter, the system was repeatedly refined but the structure of Ba₃B₂O₆ compound has not been adequately studied yet. In our study we have, for the first time, obtained the crystalline samples of Ba₃B₂O₆. The solved structure (Pbam, a = 13.5923(4) Å, b = 13.6702(4) Å, c = 14.8894(3) Å) belongs to the class of ‘anti‐zeolite’ borates with a pseudotetragonal [Ba₁₂(BO₃)₆]⁶⁺ cation pattern which contains channels along the c axis filled with anionic clusters. The Ba₃B₂O₆ compound may be regarded as a fluorine‐free end‐member of the Ba₃(BO₃)_2–xF_3x solid solution. The BaO–B₂O₃ phase diagram presented in our study is based on our research and literature data.     

Thermal Conductivity of Molten Li2O–B2O3 and K2O–B2O3 Systems

Using the transient hot‐wire method, the thermal conductivity properties of the molten Li₂O–B₂O₃ and K₂O–B₂O₃ systems were measured. The thermal conductivity increases with decreasing the temperature due to the borate structure change. In addition, calculations of the one‐dimensional Debye temperature and the phonon mean free paths as a function of temperature of the alkali borate systems were made. At a fixed temperature of 1273 K, the effect of the alkali oxide concentration on the thermal conductivity was evaluated. Within a range of 10–30 mol% Li₂O (or K₂O), a positive relationship between the thermal conductivity and 4‐coordinate boron was obtained. However, below 10 mol% Li₂O (or K₂O), the change in the intermediate‐range order of the borate structure had a more dominant effect on the thermal conductivity. Finally, the effect of cations on the thermal conductivity in the various molten R₂O–B₂O₃ (R=Li, Na and K) systems was considered. Depending on the type of cation, the change in the ionization potential had an effect on the thermal conductivity and also resulted in a change in the bond strength.     

Synthesis of hyperbranched polymers by free radical addition‐coupling polymerization with A3/B2 and A2A′/B2 approaches

Two tribromide compounds, 1,3‐(propanoic acid, 2‐bromo‐)‐2‐(2‐bromo‐1‐oxopropylamino)propyl ester (A 1 ) and trimethylolpropane tris(2‐bromopropionate) (A 2 ), were synthesized. By Cu/N,N,N′,N′,N″‐pentamethyldiethylenetriamine (PMDETA)‐mediated radical addition‐coupling polymerization (RACP) of 2‐methyl‐2‐nitrosopropane (MNP) with the tribromide compounds, two types of hyperbranched polymers were synthesized under mild conditions, respectively. Polymerization degrees of the polymers increased with time gradually, which is in line with a step‐growth polymerization mechanism. By tracing the polymerization process by gel permeation chromatography and NMR analysis, proper reaction conditions to get hyperbranched polymers was obtained. Based on the results of NMR analysis on the polymer chain structure, mechanism of forming hyperbranched polymer has been proposed, which includes formation of carbon radicals from the tribromo monomer through single electron transfer, their reaction with MNP to form nitroxide radicals, and cross‐coupling reaction of the nitroxide radicals with other carbon radicals. The gelation point of the A 2 ‐MNP system is larger than that of the A 1 ‐MNP system, indicating that probability of intramolecular cyclization in A 2 ‐MNP RACP system is higher than the A 1 ‐MNP system. The reactivity of —NHCOCH(CH₃)Br group of A 1 is lower than its two —OCOCH(CH₃)Br groups, and this resulted in longer distance between two adjacent branch points in the hyperbranched polymer of A 1 ‐MNP than the A 2 ‐MNP system. It is possible to adjust the chain structure of RACP‐based hyperbranched polymer by changing the reactivity of the functional groups in A₃ monomer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41972.