氮化硅-莫来石复合材料的制备

以莫来石、氮化硅为主要原料,铝酸钙水泥、硅微粉为结合系统,制备了氮化硅-莫来石复合材料,并与莫来石材料进行了对比。试样自然干燥24h脱模后,再经110℃烘干24h,分别在空气气氛下于1000℃、1300℃和1500℃热处理3h。检测各温度热处理后试样的体积密度(B.D)、常温抗折强度(M.O.R)、常温耐压强度(C.C.S)以及试样的热膨胀系数、耐磨性能和抗热震性能。结果表明,经过1000℃、1300℃和1500℃热处理后,氮化硅-莫来石复合材料的常温抗折强度和常温耐压强度均大于莫来石材料的常温抗折强度和常温耐压强度。在本实验条件下,在莫来石基材料中添加氮化硅并不能提高材料的耐磨性能。在1250℃～1400℃温度之间,氮化硅-莫来石复合材料的热膨胀系数小于莫来石材料的热膨胀系数。氮化硅-莫来石复合材料试样热震后的耐压强度大于莫来石材料试样热震后的耐压强度,但耐压强度保持率小于莫来石材料。     

泡沫注凝法制备刚玉-莫来石多孔陶瓷

以T60板状刚玉粉(d50=10.74μm)、ZTP-200氧化铝微粉(d50=4.96μm)、RG4000煅烧氧化铝微粉(d50=1.46μm)和NS-30型硅溶胶为原料,采用泡沫注凝法制备了刚玉-莫来石多孔陶瓷,主要研究了粉料粒度级配(d50分别为1.46、4.96、10.74μm的三种氧化铝粉料的质量分数分别为44%、26%、30%,36%、28%、36%,30%、29%、41%,21%、29%、50%)和浆料中硅溶胶加入量(质量分数分别为0、2%、4%)对坯体的烧后收缩及烧后试样的致密度、常温耐压强度、热导率、相组成和显微结构的影响。结果表明:1)d50=10.74μm的粗颗粒加入量增加,试样的烧后线收缩率、致密度和常温耐压强度减小;2)硅溶胶加入量增加,试样的烧后线收缩率和体积密度减小,但由于SiO2与Al2O3反应生成莫来石,试样的常温耐压强度变化较复杂;3)泡沫注凝法制备的刚玉-莫来石复相多孔陶瓷具有球形孔结构,平均孔径约为140μm,其性能如下:烧后线收缩率9.29%,体积密度0.78 g·cm-3,显气孔率79.8%,常温耐压强度25.3 MPa,1 000℃(热面温度)下的热导率为0.481W·m-1·K-1。     

烧成工艺对堇青石-莫来石窑具材料性能的影响

以堇青石、莫来石、高岭土和氧化铝微粉为原料制备堇青石-莫来石窑具材料,研究了烧成温度、保温时间对堇青石-莫来石窑具材料的常温性能、高温抗折强度和抗热震性的影响。并通过XRD分析了试样烧成后的物相变化,通过SEM观察了试样的显微结构。结果表明:随烧成温度从1340℃提高到1400℃,试样的线膨胀率增加,显气孔率增加,常温抗折、常温耐压强度和高温抗折强度增大,但1370℃烧成后的试样的抗热震性最好;对1370℃烧成的试样,随保温时间从3 h延长到5 h,试样的常温性能、高温抗折强度及抗热震性都有所降低。综合分析,在1370℃下保温3 h烧成的试样性能较为优良。     

刚玉莫来石复相陶瓷热震及蠕变性能的影响因素分析

采用正交设计方法研究了硅微粉、氧化铝微粉及烧成温度对刚玉莫来石复相陶瓷热震稳定性及蠕变性能的影响机制。结果表明:烧结温度对复相陶瓷热震稳定性及蠕变性的影响最大,氧化铝微粉次之,硅微粉最小。高温抗折强度损失率在烧成温度为1650℃时最低,随氧化铝的含量增加而减小,并随硅微粉含量增加而增大。蠕变率随烧成温度的提高而减少,氧化铝质量分数为7%时最低,并随硅微粉含量增加而增大。通过调节硅微粉、氧化铝微粉及烧结温度,可控制颗粒与基质、莫来石的结合状态,气孔及残留α-Al2O3,从而改善材料的抗热震性及蠕变性。     

ZrO2/Al2O3复相陶瓷的制备及性能研究

本文以工业用ZrO2和α-Al2O3微粉为原料,通过干压成型和常压烧结工艺制备ZrO2/Al2O3复相陶瓷.通过检测复相陶瓷的体积密度、显气孔率、常温抗折强度、烧后线变化率和热震稳定性,研究不同α-Al2O3微粉加入量及添加剂Y2O3对ZrO2/Al2O3复相陶瓷烧结性能、常温强度、热震稳定性及微观结构的影响,并通过SEM方法对烧后试样的微观结构进行表征.结果表明:系统配料中加入Al2O3会降低ZrO2/Al2O3复相陶瓷的致密度,常温强度随着Al2O3加入量增大而呈现先增大后减小趋势,然而热震稳定性有一定程度改善.Y2O3作为一种助烧剂可以促进ZrO2/Al2O3复相陶瓷结构内晶粒长大,加入Y2O3有利于增强复相陶瓷的烧结性.     

加入氧化铝空心球对莫来石浇注料性能的影响

为了提高以莫来石为主原料、纯铝酸钙水泥为结合剂的莫来石浇注料的性能,在其中添加氧化铝空心球,并研究其加入量(质量分数分别为0、10%、20%和30%)对该浇注料体积密度、显气孔率、热导率、常温强度、荷重软化温度、抗热震性的影响。结果表明:随着氧化铝空心球加入量的增加,试样的显气孔率增大,体积密度减小,常温抗折强度和耐压强度降低,热导率减小,荷重软化温度及抗热震性能变化不大。可见,在莫来石浇注料中引入氧化铝空心球,可明显改善浇注料的保温性能。     

堇青石加入方式对堇青石-莫来石窑具材料性能的影响

为满足锂离子电池正极材料烧成的需要,以堇青石、莫来石、高岭土和氧化铝为原料制备堇青石-莫来石窑具材料,研究了堇青石颗粒和细粉加入量对堇青石-莫来石窑具材料的常温性能、高温抗折强度和抗热震性的影响.并用XRD和SEM分析了试样烧后的物相变化与显微结构.结果表明:随着堇青石颗粒或细粉加入量从0到30％(质量分数),试样的线变化率、显气孔率、高温抗折强度增大,体积密度下降;而对常温抗折强度的影响不大,试样的耐压强度分别呈现下降或提高的趋势,试样的抗热震性先增加后降低,当堇青石颗粒含量为20％,细粉含量为20％时,试样的抗热震性最好.     

MgO-ZrO_2复合材料的烧结和热震稳定性

以烧结镁砂和单斜氧化锆粉为原料,进行了Mg O-Zr O2复合材料的制备。通过XRD和SEM-EDS分析及显气孔率、体积密度、常温抗折强度、线膨胀系数和1100℃~室温水冷热震稳定性的测试,探讨了Zr O2的用量对Mg O-Zr O2复合材料的烧结和热震稳定性的影响。结果表明:随着Zr O2用量的增加,复合材料试样的致密度和常温抗折强度呈现出先增大后减小的趋势,复合材料试样的热膨胀系数逐步减小,复合材料试样的热震稳定性呈现出先变好后变差的趋势;当Zr O2用量为30%时,Mg O-Zr O2复合材料试样的烧结性能和热震稳定性最好。     

氧化铝-莫来石高温复合陶瓷改性研究

以氧化铝、莫来石、氧化锆粉体为原料制备了氧化铝-莫来石-氧化锆复合陶瓷.使用密度测试仪、抗折强度测试仪、XRD和SEM等手段对材料的密度、力学性能进行了综合分析,尝试对影响复合陶瓷热震性能的因素及作用机理进行了讨论.研究结果表明:氧化锆弥散分布于基体晶界处,填充了基体颗粒间隙,抑制了基体晶粒长大,阻碍了裂纹扩展,提高了复合陶瓷的致密性和力学性能;ZrO2的t-m转变使基体内部产生一定的压应力区域,诱发显微裂纹的产生,分散主裂纹尖端应力,增强复合陶瓷的强度.     

刚玉–莫来石–镁铝尖晶石复合陶瓷的原位合成及热震行为

以α-Al2O3、苏州土、滑石和石英为主要原料,采用无压烧结制备了刚玉–莫来石–镁铝尖晶石多相复合陶瓷,研究了烧结温度对样品的体积密度、线性收缩率和吸水率等烧结性能以及机械性能的影响。通过X射线衍射和扫描电子显微镜分析了复相陶瓷热震前后的物相组成和显微结构。结果发现：经1480℃烧结的样品吸水率为0.19%,体积密度为3.06g/cm3,抗折强度达99.59MPa,复合材料有较好的热震性能,1100℃空冷热震损失率仅6.9%,可耐受17次热冲击。该复相陶瓷可作为潜在的太阳能热发电材料。     

玄武岩纤维对高强灌浆料耐高温性能的影响

本文研究了不同掺量、不同长度短切玄武岩纤维对高强灌浆料耐高温性能的影响,主要对玄武岩纤维对高强灌浆料在不同受火温度及300℃热震处理后的强度损失、体积变化和质量变化等的影响进行了评价。结果表明:玄武岩纤维能够提高灌浆料不同温度受火处理后的强度比,特别是抗折强度比,并且能够减小受火后灌浆料的收缩和质量损失。在300℃热震处理的条件下,玄武岩纤维能够提高灌浆料的抗压强度比,并且大幅度减少因热震造成的膨胀。     

Microstructural and mechanical properties of Al2O3 and ZTA foams prepared by thermo-foaming technique

Alumina and zirconia toughened alumina foams were fabricated through a thermo-foaming method using varying amounts of powder to sucrose weight ratio. All the fabricated foams were characterized for their compressive strength, bending strength, and fracture toughness under static loading conditions. The compressive strength increases with an increase in a weight ratio from 0.4 to 1.2. The maximum compressive strength values were found to be 1.9 MPa, and 1.8 MPa for alumina and zirconia toughened alumina foams, respectively. Further increase in powder to sucrose weight ratio led to a decrease in the compressive strength due to the partial collapse of the cell walls during the foaming process. The 3-point bend test results revealed an improvement of bending strength and fracture toughness values of zirconia toughened alumina foams compared to alumina foam, which can be attributed to the transformation toughening mechanism.     

莫来石-钛酸铝陶瓷材料性能的研究

用预合成的钛酸铝制备了莫来石-钛酸铝(MT)陶瓷材料,研究了材料组成与其烧结性能、抗弯强度、热膨胀性能及抗热震性的关系。结果表明,随着钛酸铝含量的减少,MT陶瓷材料的抗弯强度提高,热膨胀系数增大,抗热震性降低,但在钛酸铝含量大于43％时,陶瓷材料的强度有所增加,仍保持较低的热膨胀系数,具有良好的抗热震性。     

纤维和遮光剂对纳米孔粉体隔热材料性能的影响

新型高温隔热材料对工业窑炉高效节能作用显著,降低其高温辐射导热率有利于提高高温隔热性能。采用干压成型制备了添加不同种类和不同含量的纤维及遮光剂的纳米孔粉体隔热材料,分别测试了试样的常温耐压强度和不同温度下的导热系数,探讨了纤维和遮光剂对纳米孔粉体隔热材料的力学性能和隔热性能的影响,并利用SEM、EDS和FTIR对试样的微观结构和红外透射率进行了分析表征。结果表明,多晶莫来石纤维有效增强了纳米孔粉体隔热材料的耐压强度,掺杂9%(质量分数)多晶莫来石纤维试样在800 ℃的导热系数为0.047 W/(m·K),低于添加石英纤维的隔热材料;纳米SiC粉体和锆英石粉体作为遮光剂能够有效抑制辐射传热,降低高温辐射热导率,添加10%(质量分数)纳米SiC粉体遮光剂的隔热材料试样导热系数随温度的变化较小,在800 ℃仅为0.041 W/(m·K)。     

Al含量对Al2TiO5-AlN-Al材料性能的影响

采用Al2TiO5粉和Al粉为原料,经100MPa压强成形后的试样,在氮气气氛下于1400℃下烧成2h,制备出Al2TiO5-AlN-Al复相陶瓷材料。研究了金属铝含量对烧后试样性能的影响。结果表明,随着复相材料中金属铝含量的增加,试样的抗折强度与线膨胀率逐渐增加。金属铝含量为20％的复相材料试样抗折强度为27．2MPa,抗热震性能优良。     

Effect of thermal treatment on Egyptian rice straw hardboard

The effects of thermal treatment on the bending strength and water resistance of Egyptian rice straw hardboard manufactured with, or without, different amounts of resins, were investigated. The bending strength falls with increase in heating time and temperature for samples up to 1.5% resin; whereas hardboard with 3% resin showed an initial improvement in bending strength after heating at 140, 160 and 180°C. Heating samples at 200°C drastically reduces bending strength. Water resistance of all samples was improved by heat treatment.     

Development of refractory ceramics from residual silica derived from rice husk ash

Rice husk has been used as a thermal energy source for electricity generation, resulting in the formation of silica from rice husk as a by-product. This research aims to develop refractory ceramic materials by replacing kaolin clay with rice husk silica at 5%, 10% and 20% volume percentages. The samples were investigated in terms of their density, apparent porosity, tensile strength in three-point bending test, compressive strength, thermal shock and mineralogical composition. The use of 20% silica resulted in an increase in the formation of cristobalite, higher packing of granular mixtures, and consequently, an improvement in the tensile strength and compression strength of the samples. However, the material that was most successful in increasing the mechanical strength without decreasing the thermal shock strength was the sample processed with 10% clay replacement by silica from rice husk.     

Investigating the effect of andalusite on mechanical strength and thermal shock resistance of cordierite-spodumene composite ceramics

For increasing working stability of cordierite-spodumene composite ceramics for solar heat transmission pipeline, andalusite was utilized as modified additive to improve mechanical strength and thermal shock resistance of the composite ceramics. The effects of andalusite on densification, mechanical strength, thermal stability, phase composition and microstructure were studied. The experiment results showed that andalusite significantly influenced bending strength and thermal shock resistance of the composite ceramics. Especially, specimen B1 with 5 wt% andalusite sintered at 1400 °C achieved the best performances. The linear shrinkage, water absorption, apparent porosity, bulk density and bending strength were 5.62%, 0.02%, 0.06%, 2.19 g cm^?3 and 104.94 MPa, respectively. After 30 thermal shock cycles (wind cooling from 1100 °C to room temperature), the residual strength of the specimen increased to 110.65 MPa, accompanying with ?5.44% strength loss rate. The XRD and SEM analysis illustrated that mullite grains with short rod-like shape could prevent crack growth of inter-granular fracture to enhance bending strength of the specimens. Furthermore, the generation of β-spodumene grains with low thermal expansion coefficient after thermal shock improved thermal shock resistance of the composite ceramics. It is considered that the cordierite-spodumene composite ceramics with high densification, good mechanical strength and excellent thermal stability can be a potential material for high temperature thermal transmission pipeline in solar thermal power generation.     

粉煤灰细粉添加量对多孔莫来石材料的影响

为了提高粉煤灰的资源化利用,在m(漂珠):m(氢氧化铝):m(V2O5):m(AlF3)=45:55:4:3的混合料中分别添加不同量(每100 g混合料分别添加0、5、10、20、30 g)的粉煤灰细粉,以PVA溶液为结合剂,经干料混匀、泥料搅拌、泥料陈腐、挤制成型、1100℃保温2 h烧成制备莫来石试样,然后检测其致...     

Thermal Shock Behavior of an Alumina-SiC Whisker Composite

Thermal shock testing of an alumina-20 vol% SiC whisker composite showed no decrease in flexural strength with temperature differences up to 900°C. Alumina, on the other hand, normally shows a significant decrease inflexural strength with a temperature change of >400°C. The improvement in the thermal shock resistance of the composite is believed attributable to the increased fracture toughness of this material.