相变储能铝合金熔体对304不锈钢表面的侵蚀行为

发布时间：2018-04-18 10:35

  本文选题：相变储能铝合金熔体 + 304不锈钢　； 参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：相变储能技术应用的成功与否,不仅与储能材料的热物性能有关,还与储能材料熔体与容器材料的相容性有很大关系。已有研究表明:相变储能铝合金具有优良的热物性能,在太阳能热发电等高温储能方面具有广阔的应用前景,但其在高温液态环境下对铁基容器表面侵蚀严重,制约了其进一步发展和应用。针对上述问题,本文选用Al-12Si-xCu、Al-xSi-10Cu及Al-12Si-15Cu-2Mg等八种合金为储能材料,以304不锈钢为容器材料进行侵蚀试验,分别研究了在不同温度、时间及组元元素(Cu、Si和Mg)的条件下储能铝合金熔体对304不锈钢的侵蚀行为,并结合XRD分析、金相组织分析及EDS分析等揭示了储能铝合金熔体对304不锈钢的侵蚀机理,为降低相变储能铝合金熔体的侵蚀性提供了试验及理论依据。对于本论文所研究的八种合金而言,当侵蚀时间为24h,侵蚀温度范围为580℃~660℃时,304不锈钢的侵蚀速率和侵蚀层厚度都随温度的升高而增大,且当温度超过640℃时,侵蚀速率和侵蚀层厚度大幅度增加,可见侵蚀温度对侵蚀行为影响显著,低温有利于降低铝合金熔体的侵蚀性。对于本论文所研究的八种储能合金而言,当侵蚀温度为620℃,侵蚀时间由24h延长至120h时,侵蚀速率随时间的延长而降低,降低到一定程度后则保持相对稳定,即达到动态平衡状态。在Al-12Si-xCu(0≤x≤15)合金熔体对304不锈钢的侵蚀过程中,随着Cu含量的增加,侵蚀速率和侵蚀层厚度都逐渐减小。在Al-xSi-10Cu(6≤x≤15)合金熔体对304不锈钢的侵蚀过程中,当Si含量由6wt.%增加到9wt.%时,侵蚀速率和侵蚀层厚度降低,当Si含量由9wt.%增加到12wt.%时,侵蚀速率和侵蚀层厚度略有增加,当Si含量由12wt.%增加到15wt.%时,侵蚀速率和侵蚀层厚度显著增加。在Al-12Si-15Cu合金熔体中添加2wt.%Mg元素后,侵蚀速率和侵蚀层厚度都降低。由试验结果及动力学分析可知,Al-xSi-yCu-zMg合金熔体对304不锈钢的侵蚀类型为扩散侵蚀,侵蚀速率主要取决于Al元素的扩散,Cu元素和Mg元素均未参与侵蚀反应。侵蚀层是由与304不锈钢相邻的内侵蚀层和与合金熔体相邻的外侵蚀层两部组成的。内侵蚀层主要由Al95Fe4Cr相组成,呈条带状,比较致密且显微硬度高于外侵蚀层;当Si元素含量低且侵蚀时间短时,外侵蚀层主要由Fe2Al5相组成,Si填充Fe2Al5相的空位,阻碍了元素扩散,当Si元素含量高且侵蚀时间长时,外侵蚀层主要由FexSiyAlz金属间化合物、FeAl相和Al13Fe4相组成,FexSiyAlz生长速率低且可阻挡元素的扩散,从而降低侵蚀速率。在侵蚀过程中,与铝合金熔体相邻的外侵蚀层会因空洞聚集而变得疏松甚至开裂,铝合金熔体进入这些孔隙中,使得侵蚀层局部脱落,脱落块最终破裂成更细的小片并完全溶于铝合金熔体中。此外,Cr元素以金属间化合物Al95Fe4Cr的形式存在,也可阻碍元素的扩散,从而起到降低侵蚀速率的作用。
[Abstract]:The successful application of phase change energy storage technology is not only related to the thermal properties of energy storage materials, but also to the compatibility of energy storage materials melt and container materials.It has been shown that the phase change energy storage aluminum alloy has excellent thermal properties and has a broad application prospect in high temperature energy storage such as solar thermal power generation. However, it corrodes the surface of iron based containers seriously in high temperature liquid environment.It restricts its further development and application.In order to solve the above problems, eight kinds of alloys Al-12Si-xCuLi Al-xSi-10Cu and Al-12Si-15Cu-2Mg were selected as energy storage materials, and 304 stainless steel was used as container material to carry out erosion tests. The corrosion tests were carried out at different temperatures.The corrosion behavior of molten energy storage aluminum alloy to 304 stainless steel under the condition of time and component elements such as Cu-Si and Mg. combined with XRD analysis, metallographic structure analysis and EDS analysis revealed the corrosion mechanism of the molten energy storage aluminum alloy to 304 stainless steel.The experimental and theoretical basis is provided for reducing the erosivity of phase change energy storage aluminum alloy melt.For the eight alloys studied in this paper, when the erosion time is 24 h and the erosion temperature ranges from 580 鈩，

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