Studies on the development of protective coating on TZM alloy and its subsequent characterization
Studies on the development of protective coating on TZM alloy and its subsequent characterization
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DOI：
10.1016/j.jmatprotec.2007.12.075
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发表时间：
2008-10-16
影响因子：
6.3
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.
具有Mo-0.5Ti-0.08Zr-0.02C（重量%）的标称成分的TZM合金具有高的熔化温度、在高温下的上级蠕变强度和对液体金属环境（例如锌、铅、铅-铋共晶等）的优异的耐腐蚀性。因此，TZM合金被认为是各种钼合金中的主要候选者，在高温核反应堆、航空航天、发电和化学工业领域中作为耐热和结构材料的应用。然而，TZM合金具有在高温下在空气中经历快速氧化的倾向。因此，在使用前需要进行保护涂层。因此，在本研究中，尝试了利用固体渗镀技术在TZM合金表面原位形成铝化物保护涂层。本实验室首次以MoO_2、TiO_2、ZrO_2等氧化物中间体为原料，在一定量的碳存在下，采用铝热还原熔炼技术制备了TZM合金。然后将TZM合金基体的电弧熔化均质化样品包埋在由惰性基体（Al 2 O3）、涂层材料（Al）和活化剂（NH 4Cl）以适当比例取用的所选择的和紧密混合的包封组合物中。在850 ℃和1000 ℃的温度下加热包含在氧化铝坩埚中的密封装料包4-12小时。通过在TZM合金上原位沉积活性铝并随后扩散到基体中形成不同的铝化物，即Al 17 Mo 4、Al 12 Mo、Al 7 Mo 4、Al 5 Mo、Al-2（MoO 4）（3）等，获得了所需的涂层。在TZM合金表面的每一侧上获得了50 μ m的平均涂层厚度。铝化物涂层被发现是颗粒状的性质，均匀和粘附。还发现它在高温下具有足够的抗氧化性和耐磨性。(C)2008 Elsevier B. V.保留所有权利。
TZM alloy having nominal composition of Mo-0.5Ti-0.08Zr-0.02C (wt%) has high melting temperature, superior creep strength at elevated temperature and excellent corrosion resistance against liquid metal environment such as zinc, lead, lead-bismuth eutectic, etc. Hence, TZM alloy is being considered as the prime candidate among various molybdenum-based alloys for application as heat resistant and structural materials in the areas of high temperature nuclear reactors, aerospace, power generation and chemical industries. However, TZM alloy has a propensity to undergo rapid oxidation at high temperature in air. Hence it needs protective coating before use. in the present investigation, therefore, attempts were made to develop in situ formation of protective coating of aluminide over TZM alloy using pack cementation coating technique. The TZM alloy was initially prepared in this laboratory from oxide intermediates of MoO2, TiO2, ZrO2, etc. in presence of requisite amount of carbon, by alumino-thermic reduction smelting technique. The arc melted homogenized samples of TZM alloy substrate was then embedded in the chosen and intimately mixed pack composition consisting of inert matrix (Al2O3), coating material (Al) and activator (NH4Cl) taken in the judicious proportion. The sealed charge packs contained in an alumina crucible were heated at temperatures of 850 degrees C and 1000 degrees C for 4-12 h. The desired coating was achieved by in situ deposition of active aluminium over TZM alloy and its subsequent diffusion into the substrate forming different aluminides, namely, Al17Mo4, Al12Mo, Al7Mo4, Al5Mo, Al-2 (MoO4)(3),etc. An average coating thickness of 50 mu m was achieved on each side of the TZM alloy surface. The aluminide coating was found to be granular in nature, uniform and adherent. It is also found to be adequately resistant to oxidation at elevated temperature and resistant to wear. (C) 2008 Elsevier B.V. All rights reserved.