提高电熔锆刚玉砖质量的方法

提高电熔锆刚玉砖质量的方法邓延钦（江油市玻璃耐火材料厂６２１７００）目前我国已有２０多家专门生产电熔锆刚玉砖的厂家，产量基本上满足了国内市场的需要，部份代替进口产品。但与国外先进水平相比，产品质量仍有一定差距。一、主要原材料的选择生产优质电熔锆刚玉砖...     

矾土基电熔锆刚玉和锆莫来石合成料的制备、性能与结构

研究了以高铝钒土为熟料和锆英砂为原料、采用电熔工艺法制备的矾土基电熔锆刚玉和锆莫来石合成料的理化性能、物相组成和显微结构,并用这些合成料制备了Al2O3 -ZrO2 -C试样,检测其常温物理性能、高温抗折强度和抗热震性;同时还与氧化铝基电熔锆刚玉和锆莫来石合成料进行了相应性能的比较。结果表明,矾土基电熔合成料的化学矿物组成、性能和显微结构均与氧化铝基电熔锆刚玉和锆莫来石合成料的相似,而且用其生产的Al2O3 -ZrO2 -C制品的性能也达到了用氧化铝基电熔合成料所能达到的水平,可用于实际生产。     

玻璃熔窑池壁电熔锆刚玉砖的蚀损机理初探

本文以工艺岩石学的理论和方法，研究了玻璃熔窑池壁电熔锆刚玉砖蚀损后的显微结构，矿物组成及其变化，探讨了其蚀损机理，对电熔锆刚玉砖的生产和玻璃熔窑的修筑具有一定的参考价值。     

氧化法电熔锆刚玉产品开裂问题的探讨

本文根据氧化法电熔锆刚玉产品质量的主要因素－－开裂,在配方控制、电弧炉熔化、铸形设计、形组保温、产品形状等方面进行了初步的分析与探讨。     

浅谈电熔锆刚玉池壁砖的使用

根据电熔锆刚玉砖的特性,阐述了池壁砖在升温中应注意的事项、池壁在使用中的侵蚀及其维护。     

薄壁金刚石钻头的研制和在电熔锆刚玉耐火材料中的应用

电熔锆刚玉砖具有高硬度、耐高温、耐磨损、抗腐蚀等特点,因而成为玻璃熔窑的关键筑炉材料.文章通过复合电镀方法研制和生产薄壁金刚石钻头.在研制过程中,对金刚石钻头的胎体配方进行了优化,确定了电镀工艺参数,分析了金刚石参数等对钻进过程的影响,采用混目金刚石扩大了钻头的适用范围,提高了钻头的自锐性.研制的电镀薄壁金刚石钻头用于钻进锆刚玉砖耐火材料,其平均使用寿命达到6m,钻进时效为1.5m.使用结果表明胎体配方、工艺流程和电镀参数是合理的,电镀金刚石薄壁钻头是最适合钻进电熔锆刚玉砖的金刚石工具,加工后的锆刚玉砖具有精确的几何形状和高光洁度的表面.     

ESR study of paramagnetic sites in sulfated zirconia

ESR spectroscopy was used to investigate paramagnetic sites in sulfated zirconia. Catalysts derived from zirconium oxide and zirconium hydroxide were studied. It was demonstrated that paramagnetic sites assigned to near-surface F-centers were formed during activation at temperatures above 573 K. The catalyst derived from zirconium hydroxide shows after activation at 873 K two types of paramagnetic sites: F-centers and Zr³⁺ sites. Both F-centers and Zr³⁺ sites in this catalyst form complexes with reagents upon n-butane or hydrogen adsorption at range of 423–523 K in contrast to paramagnetic sites of the oxide-derived catalyst. This revised version was published online in July 2006 with corrections to the Cover Date.     

锆刚玉加入对刚玉-尖晶石浇注料性能的影响

在刚玉-尖晶石浇注料的配比组成中分别加入ZrO2质量分数为28.46%和38.47%的两种电熔锆刚玉颗粒,研究了电熔锆刚玉颗粒的粒度(5～3、3～1和1～0.5 mm)、加入量(质量分数分别为3%、5%和8%)对刚玉-尖晶石浇注料的加热永久线变化率、烧后常温抗折强度、高温抗折强度及热震后弹性模量的影响,并观察了试样的显微结构。结果表明:1)试样的加热永久线变化率随锆刚玉粒度的增大而增大,随锆刚玉加入量的增多而增大,引入锆刚玉Z40的试样的加热永久线变化率基本上比引入锆刚玉Z25的大;2)烧后试样的常温抗折强度、高温抗折强度和弹性模量均以空白试样的为最大,均随锆刚玉粒度的减小而增大,随锆刚玉加入量的增多而减小;3)在刚玉尖晶石浇注料中适当加入锆刚玉而产生微裂纹,尽管降低了材料的强度和弹性模量,但对提高抗热震性有一定的积极作用。     

Densification of copper oxide doped alumina toughened zirconia by conventional sintering

The effect of copper oxide doping (0.05–1 wt%) on the densification, microstructure evolution and mechanical characteristics of alumina toughened zirconia (ATZ: 80 wt% Y-TZP + 20 wt% Al₂O₃) ceramic composites was investigated. Green samples were pressureless sintered using a short hold time of 12 min at temperatures varying from 1250 °C to 1500 °C. The incorporation of up to 0.2 wt% copper oxide was beneficial in promoting densification at low sintering temperature and improving the mechanical properties of ATZ without affecting the tetragonal phase stability. It was found that 0.2 wt% copper oxide addition was most efficacious, and the samples could attain a relative density of approximately 92% at 1250 °C, approximately 97% dense at 1350 °C and above 99% dense at 1450–1500 °C. This approach was also accompanied by an improvement in the Vickers hardness (12.7 GPa) and fracture toughness (6.94 MPam^1/2) when consolidated at 1450 °C/12 min. In comparison, the undoped composite exhibited relative densities of approximately 80% at 1250 °C, 87% at 1350 °C and approximately 97%–98% at 1450 °C-1500 °C. However, the study also found that higher dopant levels (0.5 wt% and 1 wt%) was not beneficial because the tetragonal zirconia phase was disrupted upon cooling from sintering, resulting in the monoclinic phase formation. In addition, low densification and poor mechanical properties were obtained.     

Formation of tetramethylethylene radical cations after pentane adsorption on sulfated zirconia

Tetramethylethylene radical cations have been registered by ESR after pentane adsorption on sulfated zirconia. The radical cations proved to be not stable in the presence of oxygen, only molecular oxygen radical anions being registered. Tetramethylethylene formation and pentane disproportionation are shown to occur under illumination within the same spectral region proving that the former is formed as a by-product of pentane transformations.     

Tailoring the properties of yttria-stabilized zirconia powders prepared by the sol-gel method for potential use in solid oxide fuel cells

Yttria-stabilized zirconia (YSZ) powders have been prepared by the sol-gel method, following two alternative procedures: a series of powders was obtained by drying the sol-gel solutions in air at 100 °C until dry residue, and another series of powders was obtained by scratching the thin films deposited on cylindrical wide flat glassy surfaces after evaporating to dryness in air at 100 °C for 2 h. Samples were characterized by Scanning Electron Microscopy (SEM), nitrogen adsorption at −196 °C and Fourier Transform Infrared (FT-IR) spectroscopy. In general, a noticeable contraction of the pores is observed as the molecular size of the alcohols used grows. Powders prepared by conventional drying of sol-gel solutions at 100 °C exhibit remarkably high values of specific surface area (up to 148 m² g^− 1). On the contrary, samples prepared by scratching of the deposited thin films show a noticeable decrease in their specific surface area. Values of fractal dimension follow the same trend and indicate that, in general, the texture of the samples is mainly microporous for the first series of samples and more ordered for the second one. Finally, in order to investigate the effect of the calcination temperature on the morphological and textural properties of 3 mol% yttria-stabilized zirconia powders, once the 3YSZ powders were dried at 100 °C they were subjected to calcination at different temperatures. The experimental results suggest that the removal of residual water and alcohol occluded within the powder particles as well as the elimination of gases produced during the calcination stage play a very important role in the development of the porosity and surface area of the samples.     

Mechanical and electrochemical behavior of novel electrolytes based on partially stabilized zirconia for solid oxide fuel cells

In this study, 3 mol% yttria stabilized zirconia (3YSZ) is investigated as a SOFC electrolyte alternative to 8 mol% yttria stabilized zirconia (8YSZ). The mechanical and electrochemical properties of both materials are compared. The mechanical tests indicate that the thickness of 3YSZ can be reduced to half without sacrificing the strength compared to 8YSZ. By reducing the thickness of 3YSZ from 150 µm to 75 µm, the peak power density is shown to increase by around 80%. The performance is further enhanced by around 22% by designing of novel electrode structure with regular cut-off patterns previously optimized. However, the cell with novel designed 3YSZ electrolyte exhibits 30% lower maximum power density than that of the cell with 150 µm-thick standard 8YSZ electrolyte. Nevertheless, the loss in the performance may be tolerated by decreasing the fabrication cost revealing that 3YSZ electrolyte with cut-off patterns can be employed as SOFC electrolyte alternative to 8YSZ.     

Cobalt and iron oxide modified mesoporous zirconia: Preparation, characterization and catalytic behaviour in methanol conversion

Mesoporous zirconia materials with different textural characteristics and degrees of crystallinity were obtained by various procedures and modified with cobalt and iron oxide nanoparticles. The obtained materials were characterized by N₂-physisorption, XRD, TEM, FTIR, Mössbauer spectroscopy, TPR-TG and methanol conversion as a catalytic test. Formation of finely dispersed iron and cobalt oxide species, hosted in the zirconia matrix, was observed after the modification. The obtained composites possess higher catalytic activity and different in comparison with the corresponding zirconia supports dehydration and dehydrogenation ability. It was demonstrated that the variations in the textural and surface features of zirconia support and the deposition of different metal oxides on it provided a great opportunity for the preparation of catalysts with tunable bi-functional acidic and redox properties.     

State of platinum in zirconia and sulfated zirconia catalysts

Platinum is present in a metallic state following activation in air at 725C of both 5 wt% Pt/ZrO₂ and 5 wt% Pt/SO ₄ ^2– /ZrO₂. Reduction of either catalyst at 725C produces a Pt-Zr alloy, and these reduced catalysts, upon recalcination in air at 725C, form metallic Pt crystallites. Likewise, reduction of these uncalcined catalysts at 725C in H₂ leads to a Pt-Zr alloy formation. However, treatment of these uncalcined catalysts in H₂ at 450C does not produce Pt crystallites large enough to detect by XRD.     

Interaction between ammonium sulfate-iron oxide shown by ESR and Mössbauer spectroscopy

The ammonium sulfate-iron oxide system treated at different temperatures has been characterized by ESR, IR and Mössbauer spectroscopy. Results show that during the heat treatment some interaction between ammonium sulfate and iron oxide takes place. As a result of this interaction a surface sulfato complex of iron is formed. The complex is involved in the sites responsible for activity for acid catalytic esterification. Above 573 K, the sulfato complex will gradually decompose with a further increase in temperature. A new structure scheme of the sulfato complex is proposed.     

板状刚玉粒度和加入量对高铁镁砂-烧结刚玉复合材料性能的影响

以粒度为3~1、≤1、≤0.088 mm的高铁镁砂,≤0.088 mm的高纯镁砂为主要原料,分别研究了不同加入量(质量分数分别为3%、6%、9%、12%、15%)和不同粒度(3~2、2~1、≤1 mm)的烧结板状刚玉对试样性能的影响,并分析其物相组成和显微结构。结果表明:当烧结板状刚玉细粉加入量为6%(w)时,试样的显气孔率16%,体积密度2.99 g·cm-3,常温耐压强度80.9 MPa,荷重软化温度1 609℃,抗热震性达到20次,综合性能最好;改变加入刚玉的粒度,可以控制刚玉反应速度,同时影响高铁镁砂中Fe的扩散;铁在方镁石中固溶度大,高铁镁砂的引入可以起到方镁石改性的作用;由于铁氧化物的存在,高铁镁砂-刚玉体系在高温下易于促进镁铝尖晶石和铁铝尖晶石固溶体的形成。