共沉淀法合成磷酸盐陶瓷Ca1-xBaxZr4P6O24粉体的研究

用共沉淀法合成了磷酸锆钡钙[Ca1-xBaxZr4(PO4)6,0≤x≤1]陶瓷粉体的先驱体,研究了消除团聚并聚得结晶良好,配比准确的单相Ca1-xBaxZr4(PO4)6粉体的方法。结果表明：在共沉淀反应过程中控制pH=9,并采用低分子有机溶剂分散处理共沉淀物,可有效防止反应过程及凝固分离过程中团聚体的形成,使制备的粉体具有较窄的粒度分布,平均粒径2μm左右;采取反加料顺序并保持沉淀剂过量,可避免分别沉淀。将先驱体在900℃下煅烧2h后,经XRD分析发现为单相的Ca1-xBaxZr4(PO4)6粉体。     

液相法制备BZP族磷酸盐陶瓷粉体分散性研究

用共沉淀法合成了单相的BaZr4(PO4) 6粉体 ,研究了两种不同的分散方法制得的BZP粉体的粒度分布及其烧结体的力学性能。结果表明 :与用有机高分子分散剂PEG改性处理相比较 ,采用低分子有机溶剂分散处理所制得的BZP粉体具有较窄的粒度分布 ,平均粒径 1 6 μm～ 1 8μm ,在同样的烧结条件下 ,烧结体的抗压强度也明显优于前者。另外 ,在液相反应中控制pH =7～ 1 1 ,可有效防止反过程中团聚体的形成     

添加剂对磷酸盐陶瓷Ca1-xBaxZr4(PO4)6热膨胀性能的影响

研究了烧结助剂ZnO,MgO和晶粒生长抑制剂SiO2对NZP族陶瓷材料Ca1-xBaxZr4(PO4)6（0≤x≤1，简称CBZP）热膨胀性能的影响。结果显示：不同添加剂对CBZP陶瓷的热膨胀系数和耐热冲击性均有较大影响，以ZnO为添加剂的CBZP系列陶瓷为低热膨胀材料，由于烧结过程中晶粒过度长大导致材料耐热冲击性不好；添加MgO，SiO2均会使该系列陶瓷的平均线膨胀系数明显升高，其耐热冲击性优于前者。     

直接共沉淀法制备CaZr4(PO4)6粉体

以硝酸钙、氯氧化锆、磷酸二氢铵为原料，用直接共沉淀法制备了CaZr4（PO4）6（简称CZP）粉末。控制反应过程中溶液的pH．并用低分子有机溶剂分散处理共沉淀物，防止反应过程及固液分离过程中团聚体的形成。用TG—DTA、XRD、SEM、激光粒度分析仪对CZP粉末进行了表征。CZP粉末的结晶状况和颗粒大小及团聚情况取决于热处理温度的高低，粉体中添加3％（质量分数）氧化锌作为助烧剂及3％（质量分数）二氧化硅作为晶粒抑制剂，在1150℃下烧结2h制成CZP陶瓷。结果表明：经860℃热处理之后的粉体制成的CZP陶瓷具有较好的综合性能，弯曲强度为74．96MPa，相对密度为96．6％。     

添加剂对NZP族低热膨胀陶瓷热学性质的影响

以NZP族低热膨胀陶瓷Ca1-xBaxZr4(PO4)6(0≤x≤1)系列中的零膨胀组成Ca0.85Ba0.15Zr4P6O24为例,着重研究了不同添加剂对该零膨胀陶瓷的热膨胀异向性、平均热膨胀系数和导热性能的影响规律。实验结果表明,在烧结过程中添加质量分数1%SiO2或3%SiC均能够降低Ca0.85Ba0.15Zr4P6O24的热膨胀异向性,但与此同时,第二相的加入使Ca0.85Ba0.15Zr4P6O24的热膨胀系数有所上升。质量分数为1%～7%SiC晶须的加入反而导致NZP族陶瓷导热性能进一步降低,原因是SiC抑制了晶粒生长。     

共沉淀法制备NZP族低膨胀陶瓷前驱体BZP的工艺探索与研究

本实验用共沉淀法合成磷酸盐陶瓷粉体。合成过程中分析了加料顺序的影响,考察了反应物浓度、反应溶液的pH值、溶液反应时间、煅烧温度等因素对合成率的影响。实验结果表明：共沉淀反应过程中PH=9,采取反加料顺序,并保持沉淀剂（NH4）2HPO4过量,对共沉淀物用乙醇进行分散处理后在950℃煅烧2h,经过XRD分析发现可得到合成率极高、结晶良好的单相BaZr4（PO4）（6BZP）粉体。     

非离子表面活性剂改性羟基磷灰石粉体的制备

采用化学沉淀法将硝酸钙、磷酸氢二铵按摩尔比5:3配成溶液,加入不同质量非离子表面活性剂聚乙二醇(PEG)、聚乙烯醇(PVA),使其质量占羟基磷灰石(HA)质量分别为1％、2％、3％、4％、5％,经750℃热处理2 h,从而制取表面活性剂改性的HA粉末.对粉末进行粒度分布测量、FT-IR测试、XRD衍射分析和SEM表征.结果表明:常压60℃下制备改性的HA粉末纯度高,结晶度低.其中PEG改性HA粉末物相为Ca10(PO4)6(OH)2、Ca3(PO4)2和Ca2P2O7,添加3％PEG粉体中位径(D50)为13.55μm,OH-吸收峰最强,HA含量为纯相,结晶程度趋于完善;PVA改性HA粉末物相只有Ca10(PO4)6(OH)2,添加3％PVA粉体中位径(D50)为7.068μm,结晶程度趋于完善,HA粉末的团聚程度最小,比表面积最大为607.4 m2/kg.PVA对HA团聚程度的分散性优于PEG.     

Gd_2O_2S:Eu~(3+)发光粉的还原法合成与光致发光

采用Gd(NO3)3·6H2O、Eu(NO3)3·6H2O、(NH4)2SO4和NaOH为实验原料,通过还原法合成了Gd2O2S∶Eu3+发光粉。利用热分析(DTA-TG-DTG)、傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、扫描电子显微镜(SEM)和光致发光(PL)光谱等手段对合成的粉体进行了表征。研究表明前驱体具有晶态结构且在空气气氛中800℃煅烧2 h能转化为单相的Gd2O2SO4粉体,该粉体在氩氢混合气氛下800℃煅烧1 h能转化为单相的Gd2O2S粉体。Gd2O2S粉体呈准球形,粒径大约1μm左右,团聚较严重。PL光谱分析表明在323 nm紫外光激发下,Gd2O2S∶Eu3+发光粉呈红光发射,主发射峰位于628 nm,归属于Eu3+离子的5D0→7F2跃迁。     

纳米MgAl_2O_4粉体的溶液燃烧合成及烧结性能(英文)

以氨基乙酸和尿素为燃料,用溶液燃烧合成法制备了 MgAl2O4 纳米粉体,并研究了氨基乙酸和尿素的摩尔比(0:1,2:9 和 1:1)对粉体特性和烧结性能的影响。对粉体的扫描电子显微照片分析发现:用两种混合燃料制备的 MgAl2O4 粉体呈多孔状结构,且实验所用混合燃料有利于 MgAl2O4粉体的分散。结果表明:颗粒(团聚体)的平均粒径随所用燃料中氨基乙酸含量的增加而明显减小,粉体的比表面积随氨基乙酸含量的增加而显著增大,表明所用的混合燃料能显著降低 MgAl2O4粉体的团聚程度。此外,MgAl2O4粉体的烧结性能随所用燃料中氨基乙酸含量的增加而显著提高。     

NZP族磷酸盐晶体化合物NH4Zr2(PO4)3的水热合成

以(NH4)2HPO4为磷源,ZrO(NO3)2为锆源,用共沉淀法合成无定形前驱体,进一步采用水热晶化法制备出了NH4Zr2(PO4)3结晶化合物.研究了晶种、矿化剂(氟离子)添加量、水热合成温度和时间、pH值等对形成具有NaZr2P3O12(NZP)族晶体结构的化合物的影响,得到的最温和的水热晶化合成条件,即:按摩尔比n(F-)/n(ZrO2=1 HF引入HF作为矿化剂,添加占产物质量15%的晶种,在pH=1～5的酸性环境下,在50℃水热合成24h,可以得到结晶良好的单相NH4Zr2(PO4)3,用Brunauer-Emmett-Teller氮吸附法测定其比表面积为3.17m2/g,总孔容为0.00493mL/g.结果表明:所合成的具有三维网络状骨架结构的NZP族结晶化合物NH4Zr2(PO4)3因不具备类似微孔沸石分子筛的多孔性质,故更适合作为NZP族陶瓷的粉体材料而非分子筛催化材料.     

醇-水溶液共沉淀法制备纳米尖晶石型ZnFexCr(2-x)O4

在醇-水体系中采用沉淀法制成复合氢氧化物,再经高温煅烧制成纳米尖晶石型ZnFexCr(2-x)O4粉体材料,并用XRD,TEM和IR等方法对纳米晶进行表征.通过与传统的水溶液共沉淀法相比较,表明该方法得到的样品粉体粒径尺寸小、分布范围窄和团聚少.     

Li4+xMxSi1-xO4(M＝Fe,Cr)离子导电材料的制备与电导性能研究

采用溶胶凝胶法制备了Li4+xMxSi1-xO4(M=Fe,Cr)离子导体材料,并对样品的结构及其电导率用TG-DTA、XRD和交流阻抗仪进行了观察和测试。结果表明,采用该方法可大大降低材料的合成温度,且M(M=Fe,Cr)的掺入有利于提高材料的离子电导性。     

4-(4-氯苯基)环己醇及4-(4-氯苯基)环己酮的合成研究

以氯苯、环己烯、乙酰氯为原料,通过Friedel-Crafts反应、Baeyer-Villiger反应、水解反应得到4-(4-氯苯基)环己醇。通过正交试验得到Friedel-Crafts反应和Baeyer-Villiger反应优化后的工艺条件。4-(4-氯苯基)环己醇总收率达12.9%,较文献收率提高了6%以上。所得醇经次氯酸钠氧化,得到4-(4-氯苯基)环己酮,氧化收率87%,产品的结构经1HNMR、GC-MS鉴定。     

C0.6M0．4Zr4（PO4）6涂层的料浆性能的研究

采用料浆法和浸渍涂覆工艺在低膨胀致密碳化硅基体上制备高温耐碱腐蚀低膨胀的C0.6Mg0．4Zr4（PO4）6（C0.6M0．4ZP）涂层,研究了形成稳定C0.6M0．4ZP料浆的工艺参数及影响因素。研究结果表明,通过调整C0.6M0．4ZP的pH值、PVA加入量、固含量后,C0.6M0．4Z料浆具有很好的涂覆性能,涂覆后与基体结合紧密,基体的耐碱腐蚀性能得到改善。     

Crystal structure,densification, and microwave dielectric properties of Li3Mg2(Nb(1−x)Mox)O6+x/2 (0 ≤ x ≤ 0.08) ceramics

A novel system Li₃Mg₂(Nb_(1−x)Mo_x)O_6+x/2 (0 ≤ x ≤ 0.08) microwave dielectric ceramics were fabricated by the solid-state method. The charge compensation of Mo⁶⁺ ions substitution for Nb⁵⁺ ions was performed by introducing oxygen ions. The X-ray diffraction patterns and Rietveld refinements indicated Li₃Mg₂(Nb_(1−x)Mo_x)O_6+x/2 ceramics with single phase and orthorhombic structure. Micro-structure and density confirmed that the grain of Li₃Mg₂(Nb_(1-x)Mo_x)O_6+x/2 ceramics grew well. In addition, the permittivity of Li₃Mg₂(Nb_(1−x)Mo_x)O_6+x/2 ceramics with the same trend as density decreased slightly with increasing Mo⁶⁺ ions content. However, the Q*f and τ_f were obviously improved with an appropriate amount of Mo⁶⁺ ions. When x ≤ 0.04, the Q*f was closely related to the bond valence of samples, while when x ≥ 0.06, the Q*f was closely related to the density of samples. The variations of τ_f and oxygen octahedral distortion were the opposite. In conclusions, the Li₃Mg₂(Nb_0.98Mo_0.02)O_6.01 ceramic sintered at 1200°C for 6 hours exhibited outstanding properties: ε_r ~ 15.18, Q*f ~ 116 266 GHz, τ_f ~ −15.71 ppm/^oC.     

Thermo-structural characterization of (As2Se3)100-x-(As2Te3)x glasses for infrared optics

Differential scanning calorimetry was used to study thermokinetic behavior of (As₂Se₃)_100−x(As₂Te₃)_x infrared glasses (seven compositions along the pseudo-binary were investigated). Glass-transition kinetics was described in terms of the Tool-Narayanaswamy-Moynihan model and the relaxation motions were interpreted using Raman spectroscopy data. The enthalpy relaxation kinetics was found to be absolutely uninfluenced by changing Se/Te ratio. On the other hand, DSC crystallization behavior changed significantly with increasing As₂Te₃ content: Te-rich compositions show marked affinity toward crystallization, whereas in case of the compositions with 0-34 mol.% As₂Te₃ crystal growth is significantly suppressed. X-ray diffraction analysis indicated presence of monoclinic As₂Se₃, As₂Te₃, and As₂Se(Te)₃ phases. The complex crystallization behavior occurring in case of the Te-rich compositions was described by superposition of two autocatalytic kinetic signals. Based on the information from infrared microscopy the two overlapping crystallization processes can be attributed to the respective formations of spherulitic and needle-shaped crystallites. Best glass stability was identified in case of the (As₂Se₃)₆₆(As₂Te₃)₃₄ composition, which appears to be a potential candidate for optic applications in the far-infrared region of the spectrum.     

(Bi_(1/2)Na_(1/2))TiO_3BaTiO_3系无铅压电陶瓷工艺的研究

详细探讨了在制备(Bi1/2Na1/2)TiO3 BaTiO3(abbr.BNBT)系无铅压电陶瓷的过程中,合成条件Ty和烧结温度Ts对材料压电介电性能的影响,确定了较好的制备BNBT系压电陶瓷的工艺条件,并且系统地研究了(1-x)·(Bi1/2Na1/2)TiO3 xBaTiO3(x=0 02、0 04、0 06、0 08、0 10)的性能。XRD结构分析发现系统的相界在x=0 06,此时d33等压电介电性能参数达到最佳值。     

Novel poly(amide‐hydrazide)s and copoly(amide‐hydrazide)s from bis‐(4‐aminobenzyl) hydrazide and aromatic diacid chlorides: Synthesis and characterization

A new aromatic diamine, viz., bis‐(4‐aminobenzyl) hydrazide (BABH), which contains preformed hydrazide and methylene linkage, was synthesized starting from α‐tolunitrile. The BABH and intermediates involved in its synthesis were characterized by spectroscopic methods. Novel poly(amide‐hydrazide)s were synthesized by low temperature solution polycondensation of BABH with isophthaloyl chloride (IPC) and terephthaloyl chloride (TPC). Furthermore, two series of copoly(amide‐hydrazide)s, based on different mol % of BABH and bis‐(4‐aminophenyl) ether (ODA) with IPC/TPC were also synthesized. Poly(amide‐hydrazide)s and copoly(amide‐hydrazide)s were characterized by inherent viscosity [η_inh], FTIR, solubility, X‐ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polycondensation proceeded smoothly and afforded the polymers with inherent viscosities in the range of 0.18–0.93 dL/g in (NMP + 4% LiCl) at 30°C ± 0.1°C. These polymers dissolved in DMAc, NMP or DMSO containing LiCl. The solubility of copolymers was considerably improved in line with less crystalline nature due to random placement of constituent monomers during the copolymerization. XRD data indicated that poly(amide‐hydrazide)s from BABH alone and IPC/TPC had higher crystallinity than the corresponding copoly(amide‐hydrazide)s derived from a mixture of BABH and bis‐(4‐aminophenyl) ether (ODA). Polymers showed initial weight loss around 160°C which is attributed to the cyclodehydration leading to the formation of corresponding poly(amide‐oxadiazole)s. Copolyamide‐hydrazides showed T_max between 400 and 540°C which is essentially the decomposition of poly(amide‐oxadiazole)s. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

4-氯-2-氰基-5-(4-甲基苯基)咪唑的合成研究

以对甲基苯乙酮为起始原料,经二氧化硒氧化制得4-甲基苯基乙二醛,在水与甲醇的混合溶剂中,与盐酸羟胺、乙二醛水溶液环化反应得4-羟基-5-(4-甲基苯基)-2-肟基次甲基咪唑-3-氧,再以N,N-二甲基甲酰胺为溶剂,与二氯亚砜反应脱水氯化得标题化合物,总收率69.0%。     

Formation of (Al2OC)1−x(AlN)x solid solution starting from Al–Si–Al2O3 powder matrix at 1300°C in flowing nitrogen

(Al₂OC)_1−x(AlN)_x solid solution-reinforced Si–Al₂O₃ composite was successfully synthesized by designed heating of the Al–Si–Al₂O₃ composite to 580°C and held for 8 hours, followed by heating to 1300°C at a rate of 12°C/h in flowing nitrogen. The reaction mechanism is as follows: after the Al–Si–Al₂O₃ composite is heated to 580°C and held for 8 hours, an AlN cladding is formed on the surface of the Al powder, thus the composite is preconverted into (Al–AlN cladding structure)–Si–Al₂O₃ system. With increasing temperature, the AlN cladding ruptures and the reactive Al(l) flows out. The Al(l) preferentially undergoes active oxidation to form metastable Al₂O(g), which lowers P_O2 inside the composite and inhibits the active oxidation of Si. Moreover, ultrafine carbon is produced by the pyrolysis of the phenolic resin binder. Both metastable Al₂O(g) and ultrafine carbon are highly reactive. Therefore, under the induction of AlN and N₂, (Al₂OC)_1−x(AlN)_x solid solution is formed by the reaction which easily occurs at a relatively low temperature. In the presence of a large amount of Al₂O(g), the P_O2 in the composite does not satisfy the condition required for both Si nitridation and active oxidation, so the free Si remains stable in the composite, forming a metal-non-oxide-oxide composite. The cold crushing strength of the composites is up to 305 MPa, and the composites do not show hydration after 20 months of storage in the environment.