聚合物分解法制备微波介质陶瓷粉体的研究

对采用聚合物分解（Ｐｅｃｈｉｎｉ）法制备ＭｇＴｉＯ３粉体进行了研究，通过地聚合中间产物进行红外光谱分析，研究了聚合物分解法制备了ＭｇＴｉＯ３陶瓷粉体的聚合反应过程及产物，并与用传统固相反应法制备粉体工艺进行对比，从而证明用聚合物分解法可获得单一－ＭｇＴｉＯ３相材料，并可降低粉体的煅烧温度。     

共沉淀法制备YAG-Al2O3纳米复合粉体

本文采用共沉淀法制备了ＹＡＧ－Ａｌ_２Ｏ_３纳米复合粉体．并通过ＸＲＤ、ＴＥＭ详细研究了粉体组成、形貌随煅烧温度的变化．研究表明,在１３００℃下煅烧可获得ＹＡＧ粒径约１００ｎｍ、分散均匀、无杂相的ＹＡＧ－Ａｌ_２Ｏ_３纳米复合粉体．粉体在１４５０℃可热压烧结致密,远低于文献报道的热压烧结温度１６００℃．用共沉淀法制备ＹＡＧ－Ａｌ_２Ｏ_３纳米复合粉体具有成本低、产量高和工艺简单的优点．     

两种不同AIN粉末的烧结和热传导特性比较

本文对Ａｌ＿２Ｏ＿３碳还原氮化法和Ａｌ直接氮化法所制作的两种ＡｌＮ粉体的特性进行了分析和比较，然后研究了这两种粉体在添加０～１５ｗｔ．％的Ｙ＿２Ｏ＿３烧结助剂的条件下，经２０７３Ｋ烧结后的密度变化以及在室温下的热传导特性。     

工艺控制对NASICON物相组成的影响

用化学共沉淀方法制备了Ｎａ＿３Ｚｒ＿２Ｓｉ＿２ＰＯ＿１２（ＮＡＳＩＣＯＮ）固体电解质，研究了超细均匀的ＮＡＳＩ－ＣＯＮ预制粉体对制备ＮＡＳＩＣＯＮ所起的重要作用，检测了游离ＺｒＯ＿２的存在及其所处部位，并与无游离ＺｒＯ＿２的样品的烧成条件作对比分析，探讨了游离ＺｒＯ＿２的形成原因。     

Sc2O3稳定的ZrO2超细粉的制备与烧结

本文用化学共沉淀法制备了Ｓｃ２Ｏ３稳定的ＺｒＯ２纳米超细粉。用ＸＲＤ，ＴＥＭ，ＳＥＭ以及ＢＥＴ测比表面等方法分析了粉体和烧结体的相组成的显微结构及其性能。实验结果表明６．０、７．８、９．６ｍｏｌ％Ｓｃ２Ｏ３掺杂量的粉体易于烧结，而３．５、１２．０ｍｏｌ％Ｓｃ２Ｏ３掺杂量的粉体则不易烧结，原因在于样品冷却过程中相变引起的体积变化以及烧结体中双重显微结构的存在。     

Al_2O_3－MgAl_2O_4陶瓷的试验研究

在Ａｌ＿２Ｏ＿３中添加５－１５ｗｔ％ＭｇＡｌ＿２Ｏ＿４，采用热压注法制备Ａｌ＿２Ｏ＿３－ＭｇＡｌ＿２Ｏ４陶瓷。研究表明，Ａｌ＿２Ｏ＿３－ＭｇＡｌ＿２Ｏ＿４陶瓷具有良好的高温电阻率和抗熔渣－种子的腐蚀能力，经过进一步改进可望作为燃煤ＭＨＤ发电通道（半热壁型）阳极区电极间绝缘片材料。     

α—Fe2O3基纳米粉体的合成及其CO敏感性

本文以共沉淀法、柠檬酸络合物分解法和尿素水解法合成了掺杂的α－Ｆｅ２Ｏ３纳米粉体。用Ｘ－射线粉末衍射仪（ＸＲＤ）,透射电镜（ＴＥＭ）,比表面测定仪（ＢＥＴ）,气敏特性测试仪对所合成的粉体进行了表征和测试。结果表明,这三种方法均可合成出纳米级的粉体,用共沉淀法制备的粉体粒度较小、灵敏度较高,某些金属离子的掺杂能明显地改善粉体的气敏性。选择适当的工艺条件可制成在低温下对ＣＯ便有较高灵敏度、选择性和稳定     

溶胶共沉淀法制备ZrO2超细粉末的工艺研究

采用正交试验方法研究了溶胶共沉淀法制备ＺｒＯ２－Ｙ２Ｏ３陶瓷粉末的工艺过程，对粉体进行了粒度，ＸＲＤ，ＳＥＭ观察，结果表明，对粉体粒度影响最大的是母液浓度，而母液温度则无明显影响，母液ｐＨ值不同影响ＺｒＯ２的晶体，正交试验优化出了用ＮＨ４ＨＣＯ３作为沉淀剂制备了ＺｒＯ２粉末的最佳工艺参数，即：母液浓度１．０ｍｏｌ／Ｌ，ｐＨ＝５～６事实表明，用此法制粉成本低，周期短，效率高。     

超细BaTiO_3和掺钇半导BaTiO_3陶瓷的溶胶－凝胶法制备及其表征

采用溶胶－凝胶法制备了平均粒径小于３０ｎｍ的超细ＢａＴｉＯ＿３和未见文献报道的掺钇超细ＢａＴｉＯ＿３．并用Ｘ－ｒａｙ粉末衍射分析和化学分析对它们进行了表征;用ＴＧ－ＤＴＧ－ＤＴＡ和ＩＲ对＂ＢａＴｉＯ＿３＂干凝胶的热分解历程进行了研究;用一般陶瓷工艺制得了掺钇半导铁酸钡陶瓷并对其室温电阻率与钇含量以及烧结温度的关系进行了讨论。     

Al_2O_3对镁镧钛陶瓷介电性能及显微结构的影响

制备了具有不同Ａｌ２Ｏ３含量的镁镧钛陶瓷,并通过ＸＲＤ和ＳＥＭ及材料介电性能测试结果的分析研究了Ａｌ２Ｏ３对镁镧钛陶瓷材料的介电性能、晶相组成和显微结构的影响．结果发现,材料的相对介电常数εr随Ａｌ２Ｏ３含量的增加而降低,其品质因数Ｑ（Ｑ＝１／tｇδ）则相对保持了较高数值,最高可达１４４３０（１０ＧＨｚ）;不含Ａｌ２Ｏ３的镁镧钛陶瓷的晶相为ＭｇＴｉＯ３和Ｌａ０．６６ＴｉＯ2．９９,加入Ａｌ２Ｏ３后,出现新晶相ＭｇＡｌ２Ｏ４和Ｍｇ４Ａ１２ＴｉｇＯ２５,同时晶粒的平均尺寸有了显著的减小．     

Deposition of gold nanoparticles on electrospun MgTiO3 ceramic nanofibers

A simple method to deposit spherical gold nanoparticles on the surface of MgTiO3 ceramic nanofibers is presented. Electrospun MgTiO3/poly(vinyl acetate) (PVAc) hybrid nanofibers were calcined at 650 degrees C to obtain phase pure ceramic MgTiO3 nanofibers with 100-150 nm diameters. These ceramic nanofibers were immersed in an aqueous solution of HAuCl4 containing poly(vinyl alcohol) (PVA) as capping agent followed by photoreduction at 365 nm to get a novel Au-MgTiO3 nanocomposite. The formation of gold nanoparticles upon irradiation was confirmed by the appearance of a surface plasmon band (SPB) at 590 nm in the UV-visible absorption spectra. The surface morphology and elemental compositions were analyzed by the scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX), and transmission electron microscope (TEM). X-ray diffraction (XRD) and selected area diffraction (SAED) pattern in TEM revealed the crystallization of gold by exhibiting strong diffractions correspond to Au(111) and Au(200) crystalline planes in addition to the MgTiO3 diffraction.     

Sintering Behavior and Microwave Dielectric Properties of MgTiO3 Ceramics Doped with B2O3 by Sol-Gel Method

The B2O3-doped MgTiO3 powders and ceramics have been prepared by sol-gel method using Mg(NO3)2·6H2O, Ti(C4H9O)4 and H3BO3 as the starting materials. The sintering behavior and microwave dielectric properties of ceramics prepared from powders with different particle sizes were investigated. The gels were calcined at 650, 700, 750, 800, 850 and 900 C and the derived particle sizes of powders were 20-30 nm, 30-40 nm, 40-60 nm, 60-90 nm, 90-120 nm and 120-150 nm, respectively. The nanoparticles with the size of 30-60 nm benefited the sintering process with high surface energy whereas nanoparticles with the size of 20-30 nm damaged the microwave dielectric properties due to the pores in the ceramics. The addition of B2O3 used as a liquid sintering aid reduced the sintering temperature of MgTiO3 ceramic, which was supposed to enter the MgTiO3 lattice and resulted in the formation of (MgTi)2(BO3)O phase. The B2O3-doped MgTiO3 ceramic sintered at 1100 C and prepared from the nanoparticles of 40-60 nm had compact structure and exhibited good microwave dielectric properties: εr=17.63, Q × f=33,768 GHz and τ f= 48×10 6 C 1.     

某涂料用MgTiO_3粉体的制备研究

为克服传统固相法和液相法制粉的缺点,本文以工业级碱式碳酸镁和钛白粉为原料,采用液-固凝胶合成技术,并首次使用快速煅烧工艺制得高性能MgTiO3粉体。研究发现,1100℃×4h制备的MgTiO3粉体形状规则,且分布均匀,没有发现大的团聚体存在,d50在0.82μm左右,比表面积为2.38m2/g,MgTiO3相含量可达98%以上,酸可溶物小于1%,较适合作为涂料用填料材料。     

液相共沉淀制备镍铁尖晶石前躯体工艺研究

本文对于溶液均相共沉淀法制备镍铁尖晶石前躯粉体的工艺进行了探索研究。论文以Fe（N02）3和Ni（N02）2的混合溶液为反应物,滴加沉淀剂,进行共沉淀反应。对得到的沉淀产物进行洗涤、过滤、干燥、研磨、压制、烧结制备NiFe2O3尖晶石陶瓷粉体。通过正交试验确定了在共沉淀过程中影响共沉淀颗粒粒度的影响因素的主次顺序依次为：反应温度、搅拌速度、沉淀剂浓度、金属离子浓度;并通过反应温度和沉淀荆浓度对产率的影响试验,最终得到共沉淀反应沉淀的最佳条件。对于所制得的镍铁尖晶石陶瓷粉体检测结果表明：溶液均相共沉淀法得到的镍铁尖晶石前躯体粉末具有纯度高、粒度细的特点,并且制备出的镍铁尖晶石惰性阳极基体材料的强度显著提高。     

Al2O3添加剂对合成MgTiO3陶瓷相组成及介电性能的影响

研究了添加剂Al2O3对MgO和TiO2合成MgTiO3陶瓷烧结性，物相组成和微波介电性能的影响。XRD分析结果表明，没有添加Al2O3是，合成的MgTiO3陶瓷中只含有MgTiO3和MgTi5相,加入Al2O3，MgTiO3陶瓷中除了MgTiO3和MgTi2O5相外，还出现了MgAl2O4相，这是上由于Al2O3和MgO发生固相反应，MgAl2O4的出现虽然阻碍材料的致密化并导致密度下降，但是可能降低反应烧结合成MgTiO3陶瓷的相对介电常数和介电损耗。     

Synthesis of La(Mg0.5Ti0.5)O3 ceramics for microwave applications

La(Mg_0.5Ti_0.5)O₃ ceramics were prepared by a non-conventional chemical route, which was based on the Pechini method. For the synthesis of La(Mg_0.5Ti_0.5)O₃ powders, special attention was paid to calcination and milling conditions. Powder morphology and composition were evaluated. Fine La(Mg_0.5Ti_0.5)O₃ powders were obtained at lower temperatures than by conventional methods. Sintering under different conditions was also tested. Dense La(Mg_0.5Ti_0.5)O₃ ceramics were obtained at lower temperatures showing a single phase composition and a homogeneous microstructure. Preliminary dielectric characterization at microwave frequencies was also performed.     

Calcium oxyhydroxide (CaO/Ca(OH)2) nanoparticles: Synthesis,characterization and evaluation of their capacity to degrade glyphosate-based herbicides (GBH)

Nanometric calcium oxyhydroxides (CaO/Ca(OH)₂) were synthesized by two chemical routes, controlled precipitation and polymer complex (Pechini). The ceramic powders synthesized by the Pechini method were assessed for their ability to remove organic molecules of a glyphosate-based herbicide (GBH). The nanoparticles were characterized using ultraviolet–visible (UV–Vis) absorption, infrared (IR), and Raman spectroscopies, as well as with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Characterization revealed the synthesized particles to be nanometric in size (<100 nm), with an irregular morphology and a band gap of ~6.3 eV, evidencing a quantum confinement phenomenon. In testing for the removal of GBH with the CaO/Ca(OH)₂ synthesized by the Pechini method, a new product was formed by interaction with the organic molecules. The CaO/Ca(OH)₂-GBH interaction was so strong, at room temperature, that the solid completely dissolved, leaving no sediment. To determine the chemical nature of the resulting solution, aliquots were taken at the end of the test and analyzed by IR spectroscopy, revealing the existence in the system mainly of phosphate and phosphate-calcium groups, indicating that an important chemical reaction must have occurred between CaO/Ca(OH)₂ and HBG to modify the chemical structure of both compounds. The results obtained lead us to consider the synthesized CaO/Ca(OH)₂ nanoparticles as potential removers of agrochemical residues and other organic compounds that exist in water sources.     

Synthesis of Ba6-3xNd8+2xTi18O54 ceramic powders via citric acid precursor

Ba_6-3xNd_8+2xTi₁₈O₅₄ ceramic powders have been synthesized by the Pechini method. The precursors and derived oxide powders were characterized by DTA, TG, XRD and TEM. The effect of the molar ratio of citric acid to total metal cation concentration on the crystallization behavior of Ba_6-3xNd_8+2xTi₁₈O₅₄ was investigated. Single-phase and well crystallized Ba_6-3xNd_8+2xTi₁₈O₅₄ powders were obtained from pulverized resin at 900 °C for 3 h, without the formation of any intermediate phase, when the correct molar ratio of citric acid to total metal cations concentration is used.     

Structural,dielectric, and reflection characterization of 0.96 ZnxMg1−xTiO3–0.04 SrTiO3 ceramics

Journal of Materials Science: Materials in Electronics - The impact of Zn substitution on structural, dielectric, and reflection properties of the pure MgTiO3 and 0.96 ZnxMg1?xTiO3–0.04...     

Spritzgießen keramischer Bauteile

Powder injection moulding of ceramic parts Powder injection moulding is a parts production technology that combines the advantages of plastics injection moulding with the materials properties of ceramics. It makes possible the production of complex shaped parts for high production numbers. Almost all possibilities of parts design used in plastics injection moulding can transfered to ceramics. Paying attention to the special properties of highly filled thermoplastics and the well known rules for parts and tools construction, new parts can be realized in short development times. This article will have a closer look at the parameters for injection moulding, at rules for design of ceramic parts and the corresponding tools as well at a never debinding technology.