锆质定径水口热震稳定性的研究

本试验采用粉末成型工艺,以斜锆石和电熔部分稳定氧化锆(PMD、PCD)为原料,采用不同含量的添加剂,在300MPa压力下成型,1720℃烧制成锆质定径水口.结果表明:通过合理控制颗粒级配和优化工艺参数,氧化锆的稳定化率达到70%左右,烧成温度为1720℃保温6h后,可得到热震稳定性不小于5次的锆质定径水口.     

烧结多孔骨料制备高纯氧化锆隔热制品的性能研究

为研究烧结氧化锆多孔骨料为原料制备氧化锆制品的性能,分别以自制烧结氧化锆多孔骨料和市售氧化锆空心球为骨料,电熔氧化锆细粉和氧化锆微粉为基质,水溶性树脂为结合剂,液压成型试样经110℃干燥后于燃气窑内1800℃保温6 h烧成,检测了烧后试样的性能,分析了烧成试样的显微结构.结果表明:采用烧结氧化锆多孔原料为骨料制备的试样...     

铝锆质定径水口性能研究

以溶胶凝胶法制备的氧化铝-氧化锆复合粉体为原料,制备定径水口试样,并对其各项性能进行检测,借助XRD、SEM对其矿物相组成和显微结构进行表征.结果表明:铝锆质定径水口烧成后,致密度高,氧化铝和氧化锆在晶界处结合良好,形成刚玉-斜锆石弥散状镶嵌结构,具备均匀的显微结构和优良的抗热震性能.     

氧化锆滑板制备工艺对其性能和显微结构的影响

分别以电熔CaO稳定ZrO2(CZ,粒度分为5级,最大为1 mm,最小为5μm),电熔CaO、Y2O3复合稳定ZrO2(YCZ,其d50<5μm)和两种电熔MgO、Y2O3复合稳定ZrO2(MZY1和MZY2,粒度均为d50<5μm)为主要原料,分别采用传统颗粒级配和微粉造粒料两种工艺制备了氧化锆滑板试样,研究了原料种类、原料粒度、烧成温度对氧化锆滑板力学性能和显微结构的影响。结果表明:采用微粉造粒料制备的试样比采用传统颗粒级配方式制备的具有更高的强度和体积密度,以及更低的显气孔率;采用微粉造粒料制备的试样的抗热震性与烧成温度、稳定剂的种类和含量、氧化锆原料中SiO2和A l2O3杂质的含量等有关;采用传统颗粒级配制成的氧化锆试样难以烧结致密,颗粒与基质结合稍差,存在粗大气孔;而以造粒料制成的试样烧结致密,并有相当数量的微气孔和微裂纹。     

MgO–Al_2O_3–ZrO_2复合粉对氧化锆质定径水口改性的作用

用溶胶–凝胶法制备的化学组成不同的MgO–Al_2O_3–ZrO2复合粉作为添加剂,制备改性氧化锆质定径水口,对其体积密度、显气孔率、热震稳定性、耐压强度、物相组成和显微结构进行表征。结果表明:加入MgO–Al_2O_3–ZrO_2复合粉后,随着MgO引入量的增加,改性定径水口的体积密度降低,气孔率上升,耐压强度呈先上升后略微下降趋势,热震之后的残余强度保持率显著升高;复合粉中MgO成分的引入,降低了镁铝尖晶石对原料中MgO稳定剂的消耗,减少了固溶于ZrO_2中MgO稳定剂的脱溶,保证了改性定径水口的稳定度;改性定径水口在烧结过程中生成了大小和分布都较均匀的镁铝尖晶石和收缩微孔,同时,形成的氧化锆晶粒尺寸均匀,结合强度较好,在保证抗侵蚀性和抗冲刷性的同时,可进一步提高样品的抗热震稳定性。MgO引入量为0.65%时,相变量较为合适,定径水口的综合性能最优;当没有引入MgO时,相变量过大,水口性能下降。     

添加剂对锆质定径水口烧结性能和抗热震性的影响

采用粉末成型工艺,以粒度为0.045mm的斜锆石粉和粒度均为0.154mm和0.074mm的MgO部分稳定电熔氧化锆和CaO部分稳定电熔氧化锆为原料,分别加入不同添加剂Y2O3、CeO2和Y2O3 CeO2,在300MPa的压力下成型,并于1720℃烧后制成锆质定径水口试样。结果表明通过合理控制颗粒级配和优化工艺参数,当添加剂中Y2O3和CeO2的含量(w)分别为0.6%和0.4%时,氧化锆的稳定率约为70%,同时可得到显气孔率低,体积密度高,抗热震次数≥5次的锆质定径水口。     

纳米氧化锆添加量对氧化锆制品性能的影响

在电熔单斜氧化锆原料中添加不同数量的CaO稳定剂,制备部分稳定氧化锆,研究CaO加入量和稳定相数量的关系.在制备的CaO部分稳定氧化锆中添加纳米氧化锆粉体,经过造粒、200 MPa压力成型、干燥、1650 ℃×2 h烧成制得试样.测试试样的物理性能、分析矿物相组成、观察显微结构,研究纳米氧化锆粉体添加量对试样性能的影响.研究结果表明:2Ca-PSZ、3Ca-PSZ、4Ca-PSZ试样中,4Ca-PSZ试样稳定化程度最高;3Ca-PSZ试样显气孔率小,体积密度较大,耐压强度高.在3Ca-PSZ试样中加入纳米氧化锆粉体,随着加入量的增加,试样的显气孔率下降、烧成收缩率增加、耐压强度提高.其中纳米氧化锆粉体添加比例为8wt%时,试样气孔率为9.4%,体积密度为5.08 g/cm3,抗压强度达到381 MPa.与3Ca-PSZ试样相比,气孔率下降40%,体积密度提高5%,耐压强度提高70%.     

ZrO2-Al2TiO5复相材料的抗热冲击性能

以不同粒径的部分稳定ZrO2 (partially stabilized zirconia,PSZ)粉体为原料,采用共沉淀法包覆Al2TiO5纳米颗粒层,经高温烧结制备了高强度低膨胀的ZrO2-Al2TiO5复相材料.研究了原料粒径、Al2TiO5含量、烧成温度对复相材料的烧结性能、相组成、显微结构以及抗热冲击性能的影响.结果表明:随烧成温度的提高,PSZ各粒径样品的显气孔率呈逐步减小的规律,抗折强度呈逐步增大的趋势.随样品中纳米Al2TiO5含量的增加,单斜氧化锆到四方氧化锆的相变温度不断降低.在1 500℃烧结的、Al2TiO5含量为5%(质量分数,下同)、ZrO2(平均粒径为0.8μm)的样品,其显气孔率最小,为6.29%;抗折强度最大,为53.14MPa;室温到1100℃急冷急热冲击20次后,样品仍保持完整,仅在表面出现轻微剥落,抗热震性能明显高于其他样品.     

致密氧化锆定径水口的制备及性能研究

以粒度为0.044mm和0.002 6mm的单斜氧化锆、粒度为0.149mm和0.074mm的Y_2O_3部分稳定的电熔氧化锆和超细二次稳定氧化锆为原料,加入Y_2O_3和CeO_2复合稀土添加剂,通过200t油压机以13MPa的压力压制成型,于1 700℃下烧结得到氧化锆定径水口。结果表明:加入0.3%的Y_2O_3和0.3%的CeO_2复合稀土添加剂,同时加入15%的超细二次稳定氧化锆,制得的产品显气孔率较低,体积密度明显提高,抗热震性良好。     

氧化锆质定径水口在使用温度下矿物组成分析

为研究连铸用氧化锆质定径水口在使用温度下矿物组成和微观结构,对以氧化镁部分稳定氧化锆(Mg-PSZ)为原料制备的定径水口产品进行模拟实验研究.实验条件为:模拟浇钢使用条件试样在1540℃×5h后水淬冷却,模拟翻包后自然冷却条件试样在1540℃×5h后随炉冷却.借助X-ray荧光分析仪、X-ray衍射仪、扫描电子显微镜对试样的矿物组成及显微结构进行表征.研究结果表明:以Mg-PSZ制备的氧化锆质定径水口产品在1540℃浇钢温度下矿物相以立方相为主,在翻包自然冷却过程中,缓慢的冷却速率导致部分立方相转变为单斜相,矿物相以单斜相氧化锆为主.氧化锆质定径水口产品在高温使用环境中结构均匀,平均颗粒尺寸10 μm,而翻包自然冷却后,由于缓慢的冷却速率,定径水口产品中稳定剂脱溶,导致立方相转变为单斜相氧化锆,平均颗粒尺寸7 μm.即通过翻包自然冷却后所取试样的研究结果不能代表氧化锆质定径水口在中间包浇注过程中实际使用状态.     

氧化钇稳定氧化锆的制备及电性能测试

氧化钇稳定氧化锆(yttria-stabilized zirconia,YSZ)是目前使用最多的电解质材料,探索了以YSZ纳米粉体为原料,采用固相法制备YSZ电解质薄片。采用X射线衍射(XRD)测试了它的微结构;采用交流四端子法测瓷体的电导率。实验表明,最佳烧结温度在1300℃,气孔含量少、晶粒均匀,电导率高,800℃时为0.08 S.m-1,是理想的高温电解质材料。     

Controlled sintering and phase transformation of yttria-doped tetragonal zirconia polycrystal material

In this paper, 3 mol% yttria-doped tetragonal zirconia polycrystal material (3 mol% Y₂O₃–ZrO₂) was prepared using an optimised pressureless sintering process. The phase change and particle size distribution of Y₂O₃–ZrO₂ during sintering were studied, and the effect of sintering temperature on the properties of Y₂O₃–ZrO₂ was analysed. The raw materials and prepared samples were analysed using XRD, Raman spectroscopy, SEM, and Gaussian mathematical fitting. The results show that sintering encourages the transformation of the monoclinic phase into the tetragonal phase, thus improving the crystallinity of the sample. The relative content of the tetragonal phase in the sample increased from 57.43% to 99.80% after sintering at 1200 °C for 1 h. In the range of sintering temperatures studied in this paper (800–1200 °C), the zirconia material sintered at 1000 °C presented the lowest porosity and the best density.     

氧化锆对低品位菱镁矿制备镁橄榄石的影响

以低品位菱镁矿与天然硅石为原料,以氧化锆为添加剂,通过固相反应烧结制备镁橄榄石。研究讨论了氧化锆对镁橄榄石材料相组成、晶胞参数、微观结构及常温性能的影响。用X射线衍射（XRD）和扫描电镜（SEM）对烧后试样的相组成和显微结构进行研究。利用X′ Pert plus软件对试样中镁橄榄石相的晶胞参数进行计算。结果表明：加入适量氧化锆可以促进低品位菱镁矿轻烧氧化镁粉与天然硅石通过固相反应烧结合成制备镁橄榄石。锆离子的置换作用导致镁橄榄石相的晶胞参数和晶胞体积减小。氧化锆加入质量分数为1.2%时,镁橄榄石综合性能最好,其密度为1.87 g/cm³,显气孔率为35.1%,吸水率为18.7 %,常温耐压强度为17.9 MPa。     

Monoclinic Zirconia Microfiltration Membranes: Preparation and Characterization

Microfiltration zirconia membranes were prepared by slip casting from two pure zirconia powders derived from different processing techniques. Powders had almost the same mean particle size but were different in surface area, particle size distribution and morphology. Rheology of zirconia slips was studied in order to prepare a well-dispersed slip suitable for slip casting. The powders showed different dispersibility in the preparation of slips by colloidal processing. The effect of sintering temperature and holding time on porosity, pore size distribution, phase composition, microhardness and microstructure of unsupported membranes are studied and discussed in relation to the membrane processing and properties of powders resulting from different processing routes. Pore size distribution of membranes reflected the differences in morphology of particles and the state of agglomeration in the green samples.Isothermal sintering at 1100°C resulted in some tetragonal phase retained at room temperature in the monoclinic structure. Cracking occurred in membranes sintered above 1150°C due to the volume change in phase transformation. Densification behavior, removal of porosity and the hardness property showed differences that are attributed to the differences in powder processing and characteristics of powders. Crackfree membranes can be prepared by sintering at 1100°C from both powders.     

Cyclic Infiltration of Porous Zirconia Preforms with a Liquid Solution of Mullite Precursor

Composites of mullite and zirconia were fabricated via the cyclic infiltration of porous zirconia-based preforms with a liquid mullite precursor. The maximal amount of mullite precursor that could be infiltrated was dependent primarily on the initial open porosity of the preforms. When a zirconia preform with an initial open porosity of ∼58% was cyclically infiltrated to saturation, the open porosity was reduced to ∼43%, with a median pore diameter of 15 nm. After sintering at a temperature of 1500°C for 2 h, the saturation-infiltrated zirconia preforms could be densified to ∼98% of the theoretical density. In zirconia samples, infiltrated mullite had a tendency to coalesce into large, elongated grains as the sintering temperature was increased. The presence of infiltrated mullite did not have a significant effect on the zirconia grain structure. The distribution of mullite in the samples was nonuniform, and the distribution profiles varied as the number of infiltration cycles varied. Although the sintered density and hardness showed small improvements after saturation infiltration, the fracture toughness did not increase.     

The controlled preparation and stability mechanism of partially stabilized zirconia by microwave intensification

Partially stabilized zirconia (PSZ) occupies an important application portion in ceramics materials and refractories materials. In this work, calcium oxide-partially stabilized zirconia (CaO-PSZ) ceramics were prepared from fused zirconia by microwave sintering, with its microstructure and stability properties characterized by XRD and SEM. Results indicated that the heating rate, cooling rate, quenching temperature and isothermal treatment time rendered different influence on the stability properties, which was mainly ascribed to the reversible martensitic transformation of zirconia ceramics. Additionally, a mixed-phase composed by cubic phase ZrO₂ (c-ZrO₂) and monoclinic phase ZrO₂ (m-ZrO₂) appeared after fused zirconia treated by microwave sintering at 1450 °C for 2 h, indicating the formation of CaO-PSZ ceramics, which the finding was consistent with the SEM and EDAX analysis. Meanwhile, CaO stabilizer precipitated behavior at the crystal boundary, with the formation of acicular grains and fine particles, further rendering a toughening effect to CaO-PSZ ceramics. This work can provide important theoretical and practical significance for applications of microwave sintering to prepare CaO-PSZ ceramics material, even extending further applications in functional materials and structural materials.     

工艺参数对石英质多孔材料孔性能的影响

以长江沿岸低品位石英砂为主要原料,采用真空烧结制备了石英质多孔材料。通过实验分析发现:随烧结温度的升高、水料比的增大或发泡剂含量的增加,多孔材料的气孔率增大,抗压强度降低;而随着保温时间的延长,多孔材料的气孔率降低,抗压强度升高。通过优化得出最佳配比为:石英砂60 wt%、高岭土30 wt%、助烧剂9.6 wt%、发泡剂0.4 wt%。按这一最佳配比配料,在水料比为0.9的条件下球磨2 h制浆发泡,而后在1175°C烧结1 h,可以制备得到性能较佳的石英质多孔材料。     

二次烧结温度对牙科氧化锆陶瓷组织和力学性能的影响

研究二次烧结温度对氧化锆牙科陶瓷微观组织和力学性能的影响。方法：氧化锆亚微米粉经过干压、冷等静压成型后在1050ºC预烧结,然后将预烧结牙科氧化锆瓷块在1300ºC-1600ºC进行二次烧结。对不同二次烧结温度下材料的线收缩率、烧结密度、物相、三点抗弯强度进行测量分析,并通过扫描电镜观察试样的断面形貌。结果：结果表明随着二次烧结温度提高,氧化锆的密度、弯曲强度呈上升趋势。在1350ºC时体积密度达到6.10g/cm³,1500ºC时的机械性能最优,三点弯曲强度为852MPa,主晶相为四方相。结论：亚微米氧化锆粉体烧结活性高,力学性能优良,能够满足口腔全瓷修复材料的要求。     

低成本大孔陶瓷膜支撑体的制备与表征(英文)

以高岭土和白云石为主要原料,通过反应烧结法制备低成本大孔陶瓷膜支撑体,对制备的支撑体进行了结构和性能表征.结果表明:在高岭土中引入质量分数为20%的白云石,可显著抑制高岭土的高温烧结;加入白云石后制备的支撑体在1 150~1 300℃保温1h后,主晶相为莫来石、堇青石和钙长石,平均孔径和抗弯强度随烧成温度升高而增大,而水通量和孔隙率降低;加入20%白云石并在1 250℃保温1 h制各的大孔支撑体的孔隙率和平均孔径分别为44.6%和4.7μm,抗弯强度和纯净水通量分别达到47.6MPa和10.76m3/(m2·h·bar).