Effect of MgO addition on the sinterability and mechanical properties of mullite ceramics

Q3 Materials Science Cerâmica Pub Date : 2021-09-01 DOI:10.1590/0366-69132021673833075
T. A. Olcoski, A. Chinelatto, A. Chinelatto
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引用次数: 2

Abstract

Mullite is a refractory material with singular properties, although high temperatures and long sintering times are required to obtain this material with good densification. In this study, aluminum hydroxide and colloidal silica were used to produce mullite through reactive sintering and MgO was employed as a sintering additive. The compositions were prepared with different amounts of MgO and sintered at 1350, 1450, and 1550 °C, and then analyzed using X-ray diffraction, scanning electron microscopy, and measurements of apparent porosity (AP) and flexural strength. The results showed that the raw materials used allowed the mullite formation at relatively low temperatures (1350 °C), regardless of the amount of MgO added but with the increase in MgO content, a spinel phase appeared, resulting in a fraction of residual α-alumina. The MgO addition lowered the densification temperature at around 50 °C. Furthermore, the higher the sintering temperature and the MgO content, the larger and more anisotropic the mullite grains were. At sintering temperatures above 1450 °C, AP was reduced to approximately 10%. The MgO addition and increase in sintering temperature improved the flexural strength of mullite materials.
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添加氧化镁对莫来石陶瓷烧结性能和力学性能的影响
莫来石是一种具有独特性能的耐火材料,但要获得致密性好的材料需要高温和长时间的烧结。本研究以氢氧化铝和胶体二氧化硅为原料,以氧化镁为烧结添加剂,通过反应烧结法制备莫来石。分别在1350、1450和1550℃下进行烧结,并采用x射线衍射、扫描电镜、表观孔隙率(AP)和抗弯强度测量等方法对复合材料进行分析。结果表明:所用原料在较低温度(1350℃)下形成莫来石,与MgO添加量无关,但随着MgO含量的增加,出现尖晶石相,产生少量α-氧化铝残留。MgO的加入降低了致密化温度,达到50℃左右。烧结温度越高,MgO含量越高,莫来石晶粒越大,各向异性越强。在1450℃以上的烧结温度下,AP降低到约10%。MgO的加入和烧结温度的提高提高了莫来石材料的抗弯强度。
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来源期刊
Cerâmica
Cerâmica Materials Science-Ceramics and Composites
CiteScore
1.90
自引率
0.00%
发文量
37
审稿时长
10 weeks
期刊介绍: A Revista Cerâmica, órgão oficial da Associação Brasileira de Cerâmica (ABCERAM) publica contribuições originais de interesse na área de cerâmica, compreendendo arte cerâmica, abrasivos, biocerâmicas, cerâmicas avançadas, cerâmica branca, cerâmica de mesa, cerâmica eletroeletrônica, cerâmica estrutural, cerâmica magnética, cerâmica nuclear, cerâmica óptica, cerâmica química, cerâmica termomecânica, cerâmica vermelha, cimento, compósitos de matriz cerâmica, materiais refratários, materiais de revestimento, matérias-primas, vidrados, vidros e vitrocerâmicas, análise microestrutural, ciência básica, instrumentação, processos de fabricação, síntese de pós, técnicas de caracterização etc.
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