稳定的钛酸铝陶瓷的研究

钛酸铝瓷是低膨胀高熔点的陶瓷材料。它广泛用于高抗热震性场合以及炼铝工业。本研究利用添加剂使之生成部分莫来石提高了钛酸铝的抗弯强度,部分金属离子固溶到钛酸铝晶体中,使之提高了热稳定性。本研究制得的热稳定性钛酸铝陶瓷既保持了低膨胀性又提高了强度达到了实用水平。     

高温气体过滤器支撑体的抗热震性能改进研究

为了改善高温气体过滤器支撑体的强度及抗热震性能,根据复合材料韧化强化原理,本试验采用陶瓷材料复合技术,制备莫来石-刚玉-钛酸铝-堇青石复合陶瓷材料,探索其作为高温过滤器支撑体的可能性.以粒径小于74μm的高铝矾土熟料、钛酸铝、堇青石为原料,以聚乙烯醇的溶液(质量浓度2％)为结合剂,试样成型压力为50MPa,烧结温度为1360℃,保温3小时制备了莫来石-刚玉-钛酸铝-堇青石复合材料.对烧后试样进行体积密度、气孔率、常温抗折强度、抗热震性的测定及XRD、SEM的分析,研究了配料组成对复合材料烧结及抗热震性能的影响.研究结果表明:具有较好烧结性能与抗热震性能的莫来石-刚玉-钛酸铝-堇青石复合材料支撑体的最佳物料配比(％)为:高铝矾土熟料30％、钛酸铝10％、堇青石60％.     

钛酸铝陶瓷排气涡壳的研制

利用稳定的钛酸铝陶瓷材料研制6105无水冷增压器涡壳,对其制备工艺及材料性能进行了研究。制备涡壳用的钛酸铝材料具有良好的综合性能,其强度为51.3MPa,热膨胀系数(RT-1000℃)为1.22×10~(-6)/℃,导热系数为0.86W/m·K(600℃),试验表明,本研究制备的钛酸铝排气涡壳具有良好的隔热效果和抗热震性能以及良好的抗振动冲击性能。     

ZrSiO_4和TiO_2对铝硅系耐火材料抗热震性的影响

研究了ArSiO4（锆英石）、TiO2（铁白粉）加入物对铝硅系耐火材料抗热震性的影响及其作用机理。认为ZrSiO4、TiO2提高材料抗热震性的机理在于微裂纹增韧以及第二相（钛酸铝）降低了材料的热膨胀系数。     

提高钛酸铝陶瓷强度的研究

通过试验,本文讨论了添加ZrO_2、SiO_2、Al_1O_3、SnO_2以及烧结制度对钛酸铝材料强度的影响;研制出了一种以钛酸铝为基质的、由莫来石、锆英石等晶体增强的复合钛酸铝材料。该材料具有高温稳定(1000～1300℃中长期保温不分解)、强度高(抗弯强度≥500kg/cm~2)、热膨胀系数小(α_(20～1200℃)=8.15×10~(-7)℃~(-1))和抗热震性强等优点。     

钛酸铝陶瓷研究现状及其应用

钛酸铝（Al2TiO5）陶瓷具有低热膨胀、高熔点（1860℃）、优良的抗热震性等特点,被公认是制作低压铸造升液管、汽车发动机上排气阀、活塞头等对抗热震和隔热要求较高的组件最为理想的候选材料;然而其难以获得高强度产品及在一定温度范围内易分解的特点又限制了其应用。本文着重介绍了近年来材料工作者在粉料组成及粒度、添加剂、烧结温度等方面改善钛酸铝陶瓷材料性能所做的研究,并对钛酸铝材料的应用做了简要介绍。     

蜂窝陶瓷蓄热材料的研究现状

蜂窝陶瓷蓄热材料应该具有热膨胀系数低、比热容大、比表面积大、导热性能好、抗热震性好等特性。本文详细介绍了几种多孔陶瓷材料的优缺点,指出堇青石质复相材料是目前研究最广泛的蜂窝陶瓷材料。堇青石与多种催化剂匹配性好,比表面积大、热膨胀系数小,但耐热性稍差,于是通过添加一些添加剂来提高堇青石作为蜂窝陶瓷蓄热体的性能。这些添加剂与堇青石结合形成复相材料,可以降低热膨胀系数、提高抗热震性等。     

钛酸铝含量对Al2O3-Al2TiO5复合材料性能的影响

以预合成钛酸铝和煅烧氧化铝为原料,按不同比例混合,湿法共磨至粒径<10 um,干燥后加入PVA溶液结合剂混合,经100 MPa成型后,在1 500℃3 h下烧成,制备出Al2O3-Al2TiO5复相陶瓷材料,并研究了钛酸铝含量对烧后试样显微结构与性能的影响.结果表明:(1)随着复相材料中钛酸铝含量的增加,试样的烧后线变化率、抗折强度与线膨胀率逐渐降低;(2)钛酸铝含量为50%的试样显微结构较为致密,抗折强度为25.2 MPa,室温-1 100℃的平均线膨胀系数仅为3.6×10-6℃-1;(3)其优良的抗热震性能归因于其低热膨胀及晶界应力的共同作用,该复相材料适于用作高温作业领域的抗热震耐火材料.     

莫来石含量对堇青石-莫来石复相陶瓷性能的影响

以合成堇青石(≤0.074 mm)和合成莫来石(0.45～0.9 mm)为主要原料,a-Al2O3微粉(≤0.044 mm)、镁砂(≤0.054 mm)和熔融石英(≤0.054 mm)为添加剂,经细磨、造粒、成型后,于1 370℃4 h烧成后制备了莫来石质量分数分别为15%、20%、25%、30%、35%和40%的堇青石-莫来石复相陶瓷材料,研究了莫来石含量对复相陶瓷材料烧结性能、抗折强度、热膨胀性及抗热震性的影响.结果表明:随着莫来石含量的增加,堇青石一莫来石复相陶瓷材料的体积密度、显气孔率和热膨胀系数都呈上升趋势,而抗折强度呈降低趋势;适当提高莫来石含量有利于复相陶瓷材料的抗热震性,当莫来石含量达到30%时,材料的抗热震性最好.     

氮化硅陶瓷材料高温抗热震性能及其衰减规律研究

氮化硅陶瓷作为先进陶瓷材料具有耐高温、抗腐蚀等优异性能,因此被广泛应用于航空航天领域的强热冲击环境。热压烧结制备的Si3N4复合材料的抗弯强度较高,但抗热震性能随温度升高显著降低,热压烧结工艺在提升抗热震性能方面尚有不足。本文提出了使用二次热处理烧结方式来提高Si3N4陶瓷的抗热震性能,通过热压烧结-气压烧结二次热处理的烧结方式获得更致密、抗热震性能更好的Si3N4陶瓷材料。测试结果显示,常规热压方式制备的氮化硅陶瓷,随着热震温度的升高、次数的增加,材料内部产生微裂纹的概率增大,热震后试样抗弯强度逐渐降低,1200℃时平均强度下降率达23.48%。而经过二次热处理后氮化硅陶瓷抗弯强度略有降低,但抗热震性能得到明显改善,随着热处理时间增加,二次热处理后氮化硅陶瓷显微结构更加致密,抗热震性能将明显提高,热震后强度下降率明显减小,1200℃热震10次后强度下降率为12.25%。本文提出了提高Si3N4陶瓷的抗热震性的方法,探讨了氮化硅陶瓷在1200℃高温下的抗热震性能及其衰减规律,为改善氮化硅陶瓷器件高温性能提供了参考。     

Development of Aluminum Titanate-Mullite Composite Having High Thermal Shock Resistance

Thermomechanical properties of aluminum titanate-mullite composites were studied for a wide composition range to develop material having high thermal shock resistance. The thermal shock resistance tended to increase with increasing aluminum titanate content. Composite having 82 vol% aluminum titanate can withstand water quench from above 1200°C and has a room-temperature strength of 60 MPa. Composite with less aluminum titanate has lower thermal shock resistance but has higher strength. The relation between thermal shock resistance and strength, Young's modulus, and thermal expansion coefficient is discussed.     

Sintering behavior and thermal shock resistance of aluminum titanate (Al2TiO5)-toughened MgO-based ceramics

In order to improve the thermal shock resistance of MgO-based ceramics, aluminum titanate (Al₂TiO₅)-toughened MgO-based ceramics were successfully prepared by solid state sintering at 1450 °C and 1550 °C for 3 h starting from MgO and as-synthesized Al₂TiO₅ powders. The effects of various contents of Al₂TiO₅ second phase on the sintering behavior and thermal shock resistance of MgO-based ceramics were investigated. The sintering behavior of sintered samples was evaluated by comparing the relative density, apparent porosity, bending strength, phase composition as well as microstructure. The thermal shock resistance of sintered samples was characterized by using the residual bending strength after three thermal cycles and thermal expansion coefficient. The obtained samples with 10 wt% Al₂TiO₅, which were sintered at 1550 °C for 3 h, showed the highest relative density, lowest apparent porosity as well as optimum bending strength. In addition, the samples added 15 wt% Al₂TiO₅ at 1550 °C with a dwell time of 3 h were the highest residual bending strength and lowest thermal expansion coefficient. It revealed that the enhancement in thermal shock resistance was ascribed to the reduction of thermal expansion coefficient.     

Properties of products based on aluminum titanate and alumina

Conclusions Aluminum titanate containing additions of alumina and aluminum phosphate is a promising material for making articles with a low or practically zero coefficient of thermal expansion at temperatures of up to 500°C.It is of interest to do further work to find materials based on aluminum titanate, alumina and aluminum phosphate with zero coefficients of expansion in various temperature ranges.The addition of alumina and aluminum phosphate confers an adequate strength to the components of aluminum titanate, a high spalling resistance (including metal resistance) with a refractoriness of the order of 1930°C.     

Influence of a Dispersion of Aluminum Titanate Particles of Controlled Size on the Thermal Shock Resistance of Alumina

The possibility of developing fine-grained (∼0.5–3 μm) and dense (≥0.98ρ_th) alumina (90 vol%)–aluminum titanate (10 vol%) composites with improved thermal shock resistance and maintained strength is investigated. One alumina material and one composite with similar microstructures (porosity and grain-size distribution) were fabricated to investigate the effect of Al₂TiO₅ on thermal shock behavior. The size of the Al₂TiO₅ particles was kept under 2.2 μm to avoid spontaneous microcracking. The mechanical and thermal properties of the materials involved in their response to thermal shock and the results for the evolution of indentation cracks of equal initial crack length with increasing Δ T in samples quenched in glycerine are described. The combination of thermal and mechanical properties—thermal conductivity, thermal expansion coefficient, Young's modulus, and toughness—improve the thermal shock resistance of the alumina–aluminum titanate composite in terms of critical temperature increment (>30%). The suitable structural properties of alumina—hardness and strength—are maintained.     

添加线胀材料对瓷器坯体抗热震性的影响

以锂辉石、堇青石、钛酸铝三种线胀系数较低的材料作为添加剂,单独或复合加入到普通瓷器坯料中,研究了加入不同比例的上述材料来降低陶瓷坯料线胀系数、提高产品抗热震性的可行性。     

不同原料制备钛酸铝陶瓷性能比较

采用2种原料分别为高铝矾土和氧化钛、工业氧化铝和氧化钛。粉料经过预烧之后经成形、烧结制备陶瓷。为了比较2种制品。分别对其进行了抗压强度、抗折强度、热膨胀系数、热震稳定性测试及微观形貌观察。结果表明．采用前者为原料制备的陶瓷性能可以与后者相媲美。同时由于高铝矾土价格便宜．因此更适用于工业生产的需要。     

Stabilized tialite–mullite composites with low thermal expansion and high strength for catalytic converters

Aluminium titanate (AT) is a potential candidate material for use in demanding high temperature applications, because it exhibits an excellent thermal shock resistance due to its low thermal expansion coefficient and high refractoriness.However, industrial applications of this material are hindered by two major limitations. Its decomposition to α-Al₂O₃ and TiO₂ between 800 and 1280 °C and its low mechanical strength.The present work aims to stabilize aluminium titanate with the addition of Fe₂O₃. The decomposition of aluminium titanate–iron oxide solid solutions when heated at 1100 °C for up to 1000 h was studied. The effect of iron oxide addition on pure aluminium titanate properties was investigated. Additionally, strengthening of the iron stabilized AT with mullite was considered adding mullite (M), 3Al₂O₃·2SiO₂ to tialite body at various amounts (5–50%, w/w). Properties like four point bending strength, thermal expansion coefficient (TEC), and porosity of the composites, were evaluated. Finally, the effect of mullite on the mechanical properties of AT–mullite composites was investigated.It was found that aluminium titanate (iron oxide stabilized)–mullite composites exhibit very good mechanical strength combined with excellent thermal stability.     

Application of optical methods to investigate the non-linear asymmetric behavior of ceramics exhibiting large strain to rupture by four-points bending test

Large strain to rupture behavior is essential, for refractory materials, to improve their thermal shock resistance. The non-linear comportment under loading of specific developed ceramics associated to their type of microstructure (micro-cracked) leads to the possibility to increase their strain-to-rupture level. Aluminum titanate (AT: Al₂TiO₅) ceramics are one of these materials and are characterized by a mechanical behavior strongly dependent on their microstructure. Indeed, this behavior can vary from a fragile one to a large non-linear one according to the degree of microcracking present within the material. The paper here presented is devoted to the study of this nonlinear behavior thanks to four-points bending test associated with digital image correlation technique to determine kinematics fields. Results highlight the asymmetric character of the mechanical behavior of a microcracked aluminum titanate. A comparison between the Young moduli and fracture strength obtained using conventional and ones identified by digital image correlation will be done.     

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。