Development of silicide coating over molybdenum based refractory alloy and its characterization
Development of silicide coating over molybdenum based refractory alloy and its characterization
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DOI：
10.1016/j.jnucmat.2010.06.014
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发表时间：
2010-08-01
影响因子：
3.1
通讯作者：
Suri, A. K.
中科院分区：
文献类型：
--
作者：
Chakraborty, S. P.;Banerjee, S.;Suri, A. K.
钼基难熔合金是高温紧凑型核反应堆和聚变堆结构应用的潜在候选材料。然而，这些合金在高温下极易在空气或氧气中氧化，因此会受到高度挥发的三氧化钼物种的严重损失。因此，本研究探讨了用复合渗层技术在钼基TZM合金(Mo>；99wt.%)上开发硅化物型涂层的可行性。本实验室采用铝热还原熔炼技术，以MoO_2、TiO_2、ZrO_2等氧化物中间体为原料，在适量碳存在下合成了TZM合金。然后将TZM合金基材的电弧熔化和均化样品按适当的比例嵌入到由惰性基质(Al_2O_3)、涂层粉末(Si)和激活剂(NH_4Cl)组成的选定的紧密混合的填充成分中。将氧化铝坩埚中的密封电荷包在1000℃的温度下加热8-16小时以形成涂层。经X射线衍射仪分析，涂层相为MoSi2。用扫描电子显微镜对涂层的形貌进行了研究。结果表明，涂层为扩散结合，涂层中的Si向内扩散，TZM衬底中的Mo向外扩散形成涂层。当在1200℃的空气中测试时，发现涂层具有抗氧化性。在衬底的每一侧达到了最大100微米的涂层厚度。(C)2010爱思唯尔B.V.保留所有权利。
Molybdenum based refractory alloys are potential candidate materials for structural applications in high temperature compact nuclear reactors and fusion reactors. However, these alloys being highly susceptible to oxidation in air or oxygen at elevated temperature, undergoes severe losses from highly volatile molybdenum trioxide species. Present investigation, therefore, examines the feasibility of development of silicide type of coating over molybdenum base TZM alloy shape (Mo > 99 wt.%) using pack cementation coating technique. TZM alloy was synthesized in this laboratory from oxide intermediates of MoO2, TiO2 and ZrO2 in presence of requisite amount of carbon, by alumino-thermic reduction smelting technique. The arc melted and homogenized samples of TZM alloy substrate was then embedded in the chosen and intimately mixed pack composition consisting of inert matrix (Al2O3), coating powder (Si) and activator (NH4Cl) taken in the judicious proportion. The sealed charge packs contained in an alumina crucible were heated at temperatures of 1000 degrees C for 8-16 h heating cycle to develop the coating. The coating phase was confirmed to be of made of MoSi2 by XRD analysis. The morphology of the coating was studied by SEM characterization. It had revealed that the coating was diffusion bonded where Si from coating diffused inward and Mo from TZM substrate diffused outward to form the coating. The coating was found to be resistant to oxidation when tested in air up to 1200 degrees C. A maximum 100 mu m of coating thickness was achieved on each side of the substrate. (C) 2010 Elsevier B.V. All rights reserved.