Chang Shu-Wei, Shiue Ren-Kae, Huang Liang-Wei
Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan.
Chemistry and Environment Research Laboratory, Taiwan Power Research Institute, Taiwan Power Company, New Taipei City 238, Taiwan.
Materials (Basel). 2025 Apr 25;18(9):1956. doi: 10.3390/ma18091956.
This study attempts to use fly ash as the brazing filler additive to increase the sustainable use of coal-fired power plant by-product materials. The experimental results show that adding 5 wt% fly ash into the Ag paste filler contributes to the interfacial reactions in heterogeneous reactive air brazing (RAB) of the ZrO and Crofer alloy. The Ag-rich phase dominates the brazed zone. The interfacial reaction layers contain oxidation of the Cu-Ti coating layer, Crofer alloy, and the Si/Al-rich oxides from the fly ash particles. The 5% fly ash RAB joint maintained airtightness for 280 h under 2 psig helium at room temperature. When the test temperature was raised to 600 °C for 24 h, the pressure of the joint assembly still did not drop. When the fly ash addition was increased to 10 wt%, the joint assembly was no longer leak-free at room temperature. Many visible voids and cracks exist in the brazed zone and at the ZrO/braze and braze/Crofer interfaces. A high volume fraction of the fly ash particles results in many brittle Si/Al-rich oxides in the joint after RAB, and the fracture of these oxides significantly deteriorates the airtightness of the joint. This study shows the feasibility and potential of introducing 5 wt% fly ash particles to the Ag-rich paste filler during the RAB of ZrO and Crofer for airtight applications.
本研究试图将粉煤灰用作钎料添加剂，以提高燃煤电厂副产品材料的可持续利用率。实验结果表明，在银膏填料中添加5 wt%的粉煤灰有助于氧化锆（ZrO）与克罗费尔合金在非均相活性空气钎焊（RAB）中的界面反应。富银相在钎焊区占主导地位。界面反应层包括铜钛涂层、克罗费尔合金的氧化，以及粉煤灰颗粒中的富硅/铝氧化物。5%粉煤灰RAB接头在室温2 psig氦气下保持气密性280小时。当测试温度升至600℃并保持24小时时，接头组件的压力仍未下降。当粉煤灰添加量增加到10 wt%时，接头组件在室温下不再无泄漏。在钎焊区以及ZrO/钎料和钎料/克罗费尔界面处存在许多可见的气孔和裂纹。高体积分数的粉煤灰颗粒导致RAB后接头中出现许多脆性的富硅/铝氧化物，这些氧化物的断裂显著降低了接头的气密性。本研究表明，在ZrO与克罗费尔的RAB过程中，向富银膏状填料中引入5 wt%粉煤灰颗粒用于气密应用具有可行性和潜力。
