【作者】 郑建明；

【导师】 杨辉；

【作者基本信息】 浙江大学 ， 材料学， 2005， 硕士

【摘要】 本课题针对95氧化铝陶瓷生产过程中存在的破损率较大和直接加入ZrO₂韧化成本较高的问题,通过采用廉价的锆英石作为ZrO₂源来韧化95瓷,不但可以解决95瓷的脆性问题,而且可以降低生产成本,这在生产实际中具有非常重要的意义。 本文以锆英石为ZrO₂源,在95瓷中引入第二相,制备了韧化95氧化铝陶瓷,并与直接加入ZrO₂相制备的韧化95氧化铝陶瓷作对比。分别对它们的烧结性能、体积密度、力学性能进行测试,对试样的微观结构和相组成进行分析,讨论了试样晶相组成和显微结构与韧化95氧化铝陶瓷性能之间的关系。最后对锆英石为ZrO₂源制备的韧化95氧化铝陶瓷的烧结过程和反应机理进行了简单的探讨。得出以下重要结论: 1.比较了两种不同zrO₂源对95氧化铝陶瓷基体性能的改进作用,得出: a).直接在95瓷中添加ZrO₂,会导致原95瓷的烧结温度升高,在原有工艺条件下难以获得致密化烧结,若要获得结构致密的瓷体就必须提高烧结温度,这对工业生产能耗角度考虑是极为不利的。并且,烧结体中的ZrO₂多数还是以单斜相保留下来,缺少相变增韧的条件,难以获得力学性能优良的陶瓷。 b).以锆英石为ZrO₂源引入95氧化铝陶瓷中,在同等工艺条件下能得到致密化烧结的陶瓷。并且随着锆英石添加量的增加,陶瓷的韧化效果呈现先增大后减小的趋势。 c).锆英石在95氧化铝基体中引入ZrO₂来韧化95瓷的方法是合理可行的。 2.通过对95氧化铝陶瓷基础配方的选择、优化,控制所添加锆英石的粒度、比例,选择合适的烧结曲线可获得力学性能优越的95氧化铝陶瓷。通过大量的实验及分析,得出: a).氧化铝陶瓷中添加少量的MgO可使基体晶粒得到细化;添加Y₂O₃并与锆英石进行预烧,有助于反应后得到的四方相ZrO₂得以在常温下保留,为四方ZrO₂通过更多还原

【Abstract】 During the manufacturing of 95 alumina ceramics, high damage is a significant problem, for its brittleness. ZrO₂ can tough alumina ceramics by the mechanism of stress induced phase transformation, but the cost was high. Our research project aimed to solve the problem by prepared ZrO₂ toughed ceramics using the raw material of zircon, which is cheaper than ZrO₂. Through this method, not only the problem can be well solved, but also cut down the cost. So this project is of unique importance as to practical production.In this experiment, 95 alumina ceramics was toughed by adding zircon as the source of ZrO₂. For contrast, another sample of 95 alumina ceramics was prepared by add ZrO₂ directly. The samples’ sintering properties, bulk density and mechanical properties were tested. And their microstructure and phase constituent were investigated. Based on the data, the relation between structure and property were discussed. In the last, the sintering process and the reaction mechanism were discussed. We draw the conclusions as followed:1. Compared the improvement of properties of 95 alumina ceramics, which wereprepared by two different sources of ZrO₂, and arrived the conclusions as followed: a). Adding ZrO₂ directly to the 95 alumina ceramics will results in sintering temperature heading up. Therefore under the same process condition, the ceramics can not be well sintered. The high density ceramics can be attained only by elevating the sintering temperature. However, from the point of saving energy that was not what manufacture expected. Also, through this method only monocline ZrO₂ was founded in the matrix of 95 ceramics, which lacks the requirement of toughness of stress induced phase transformation. So ceramics with high performance can not be obtained in this way. b). For the sample with the zircon additive, which can be well sintered under the same condition. The result shows the effect of toughenness relates to the zircon content. At the first, the fracture toughness of ceramics increased with content of zircon, then decreased with the continuous increase of the zircon additive.c).Using zircon as additive to toughing 95 alumina ceramics was reasonable and feasible.2. The composition 95 alumina ceramics was designed and optimized in our experiment. Ceramics with high mechanical performance can be attained through controlling the particle size, the content of zircon, and sintering under proper temperature. According to the experiment and investigation, we arrived the conclusions as followed:a). 95 alumina ceramics with fine grain size can be obtained by adding small content of magnesia; Y2O3 pre-sintered with zircon, then used as an additive will help reserving the t-ZrO2 at room temperature, which contribute to prove the mechanical properties of 95 alumina ceramics. The optimal content of zircon in the matrix of 95 alumina ceramics was 4.5 wt%.b). The particle size of zircon also play a significant role on the properties of the 95-alumina ceramics. When the matrix grain size was close to that of zircon particle, can reached an ideal effect, the fracture toughness up to 6.04 MPa-m1/2, which was 1.5 times as high as common 95 alumina ceramics.3. The sintering process and the reaction mechanism of toughed 95 alumina ceramics which was prepared by adding zircon as the resource of ZrCh were discussed. From the discussion, we found that:a). The decomposition temperature of zircon decreased and zircon was almost completely decomposed since the sintering additive of 95 alumina ceramics. The whole process of reaction sintering should be sintering —> reacting —> sintering.b). There exists an competition for SiC>2 among zircon, mullite and the formation of low-melting liquid with CaO. The competition results in no mullite emerged during the process of reacting.更多还原