Near-Net-Shaped Porous Ceramics for Potential Sound Absorption Applications at High Temperatures
Near-Net-Shaped Porous Ceramics for Potential Sound Absorption Applications at High Temperatures
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DOI：
10.1111/jace.12160
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发表时间：
2013-03
影响因子：
3.9
通讯作者：
M. Carlesso;R. Giacomelli;S. Günther;D. Koch;Stephen Kroll;S. Odenbach;K. Rezwan
中科院分区：
文献类型：
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作者：
M. Carlesso;R. Giacomelli;S. Günther;D. Koch;Stephen Kroll;S. Odenbach;K. Rezwan
我们提出了一种有趣的工艺路线，以获得具有可控孔隙率和气流阻力的氧化铝/莫来石基陶瓷，从而导致有前途的微结构应用于吸声器。陶瓷材料的使用目标是在高温或腐蚀性大气占主导地位的潜在应用中，例如在燃气轮机的燃烧室中。对于多孔陶瓷的生产，我们结合了冷冻凝胶和牺牲模板工艺，在环保和低成本的条件下，生产出低收缩率（<3%）的近网形零件。所得微观结构呈双峰型孔径分布，由冻结胶凝过程形成的小孔隙（~30 μm）连接膨胀聚苯乙烯模板颗粒形成的大孔隙（直径2 ~ 5mm）。这些连接在本研究中被称为“窗口”，对吸声性能有显著影响，使压力扩散效应发生，吸声系数显著提高。通过改变模板颗粒含量和浆料固体含量，可以控制开孔陶瓷在不同频率下的吸声行为。这些陶瓷具有77%至82%的高开孔率，并具有0.27至0.68 MPa的抗压强度和0.30-0.99的吸声系数，代表了在腐蚀环境和高温下控制和降低噪音的非常有前途的组合性能。
We present an interesting processing route for obtaining alumina/mullite-based ceramics with controlled porosity and airflow resistance leading to promising microstructures for application as sound absorbers. The use of ceramic materials aims for potential applications where high temperatures or corrosive atmospheres are predominant, e.g., in combustion chambers of gas turbines. For the production of the porous ceramics we combined freeze gelation and sacrificial templating processes to produce near-net-shaped parts with low shrinkage (<3%) based on environmental-friendly and low cost conditions. The obtained microstructure presents a bimodal pore size distribution, with small pores derived from the freeze gelation process (~30 μm) connecting large pores (2–5 mm diameter) originated from the expanded polystyrene template particles. These connections, called “windows” in this study, show a significant impact on the sound absorption properties, allowing the pressure diffusion effect to take place, resulting in a significant improvement of the sound absorption coefficient. By varying the template particle content and the slurry solid content, it is possible to control the sound absorption behavior at different frequencies of the open-celled ceramics. These ceramics feature a high open porosity, from 77% to 82%, combined with sufficient compressive strength ranging from 0.27 to 0.68 MPa and sound absorption coefficients of 0.30–0.99, representing a highly promising combination of properties for noise control and reduction at corrosive environments and high temperatures.