發(fā)布時間：2019-06-29 17:33

【摘要】：多孔陶瓷由于在化學(xué)穩(wěn)定性、透過性、力學(xué)性質(zhì)、抗高溫氧化及抗熱震等方面都具有十分優(yōu)異的性能,而被廣泛的應(yīng)用于保溫隔熱材料、過濾器、催化劑載體、生物材料、燃料電池材料、熱交換器等。 多孔陶瓷用于保溫隔熱材料時,要求氣孔以閉口孔為主,但傳統(tǒng)的制備方法存在孔徑不易控制、氣孔分布不均勻等缺點(diǎn)。本文運(yùn)用凝膠注模和發(fā)泡法相結(jié)合的方法,即凝膠—發(fā)泡法,成功的制備出了閉口孔率高、孔徑小、氣孔分布均勻的氧化鋁多孔陶瓷。 本文推導(dǎo)了熱導(dǎo)率的計算公式,從理論上分析了熱導(dǎo)率的影響因素；對凝膠—發(fā)泡法的機(jī)理進(jìn)行了初步的研究,研究了發(fā)泡劑對凝膠形成的影響；研究了坯體的DSC—TG曲線,確定了排膠工藝；研究了固相含量、發(fā)泡劑添加量、燒結(jié)助劑的添加量、燒結(jié)溫度對樣品性能和結(jié)構(gòu)的影響；分析了氣孔率對熱膨脹性能的影響。得到了以下結(jié)論： 通過對熱導(dǎo)率計算公式的分析表明：氣孔率越高,測試溫度越低,孔徑越小,則氧化鋁多孔陶瓷的熱導(dǎo)率就越低,其隔熱保溫效果越好。 由于氧阻聚效應(yīng),發(fā)泡劑的加入會對凝膠的形成產(chǎn)生一定的影響,從而使凝膠時間增加,凝膠強(qiáng)度降低。適當(dāng)?shù)脑黾佑袡C(jī)單體、交聯(lián)劑和引發(fā)劑的用量,可以在一定程度上減少凝膠時間,增加凝膠強(qiáng)度。 有機(jī)物的分解溫度區(qū)間為200℃-500℃,確定排膠工藝為從室溫到200℃,升溫速率為5℃/min；從200-500℃,升溫速率3℃/min；500℃保溫一小時 漿料的固相含量為45%、發(fā)泡劑加入量為1%、燒結(jié)助劑加入量為1%、燒結(jié)溫度為1500℃時,可制備出性能優(yōu)異的多孔氧化鋁陶瓷,此時氧化鋁多孔陶瓷的氣孔率為56%,其中閉口孔率為51%,抗彎強(qiáng)度為23MPa,氣孔分布均勻,孔徑約15～120μm。 氧化鋁多孔陶瓷的熱膨脹系數(shù)與氧化鋁陶瓷的熱膨脹系數(shù)近似相等,氣孔率的變化對多孔氧化鋁陶瓷膨脹性能的影響并不明顯。
[Abstract]:Porous ceramics have been widely used in thermal insulation materials, filters, catalyst carriers, biomaterials, fuel cell materials, heat exchanger and so on because of their excellent properties in chemical stability, permeability, mechanical properties, high temperature oxidation resistance and thermal shock resistance. When porous ceramics are used in thermal insulation materials, pores are required to be mainly closed holes, but the traditional preparation methods have some shortcomings, such as difficult to control pore size, uneven distribution of pores and so on. In this paper, alumina porous ceramics with high closed porosity, small pore size and uniform pore distribution were successfully prepared by using the method of gel injection mould and foaming method, that is, gel foaming method. In this paper, the calculation formula of thermal conductivity is deduced, and the influencing factors of thermal conductivity are analyzed theoretically; the mechanism of gel-foaming method is studied, and the effect of foaming agent on gel formation is studied; the DSC-TG curve of billet is studied, and the gel discharge process is determined. The effects of solid phase content, foaming agent addition, sintering assistant addition and sintering temperature on the properties and structure of the sample are studied. The effect of porosity on thermal expansion was analyzed. The following conclusions are obtained: the higher the porosity, the lower the test temperature and the smaller the pore size, the lower the thermal conductivity and the better the thermal insulation effect of alumina porous ceramics. Due to the effect of oxygen inhibition, the addition of foaming agent will have a certain effect on the formation of the gel, so that the gel time increases and the gel strength decreases. By properly increasing the amount of organic monomer, crosslinker and initiator, the gel time can be reduced and the gel strength can be increased to a certain extent. The decomposition temperature range of organic matter is 200 鈩，

本文編號：2507991