Advanced Coatings on High Temperature Applications
Advanced Coatings on High Temperature Applications
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DOI：
10.4028/www.scientific.net/msf.522-523.1
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发表时间：
2006-07
期刊：
影响因子：
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通讯作者：
T. Narita;T. Izumi;T. Nishimoto;Y. Shibata;K. Z. Thosin;S. Hayashi
中科院分区：
文献类型：
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作者：
T. Narita;T. Izumi;T. Nishimoto;Y. Shibata;K. Z. Thosin;S. Hayashi
为了抑制涂层和合金基底之间的相互扩散，除了确保在非常高的温度下缓慢的氧化物生长之外，还开发了先进的涂层，并且它们被分为四组，（1）具有双层结构的扩散阻挡涂层，（Re-Cr-Ni）相作为扩散阻挡层和外部Ni铝化物作为铝储存器形成在Ni基高温合金、Hastelloy X和Nb基合金上。(2)采用化学镀镍结合高活性铝包埋渗的方法，在TiAl金属间化合物和钛基耐热合金表面形成了双层结构的上坡扩散涂层，内层为TiAl 2 + L12，外层为β-NiAl。(3)采用两步Cr / Al包埋工艺，形成了双层结构的化学阻挡层，内层为 * γ + β + Laves三相混合物作为化学扩散阻挡层，外层为富Al的γ-TiAl作为Al贮库。(4)Ni-（2050）at% Cr合金表面的δ-Ni 2Al 3涂层在高温氧化过程中发生了变化，形成了内部为α-Cr扩散阻挡层，外部为β-NiAl贮铝层的双层结构自形成涂层。在1173和1573 K之间的温度下，在空气中长达1,000小时（对于上坡扩散涂层为10,000小时），研究了涂覆合金的氧化性能。在1423 K下氧化至1800 ks时，Re-Cr-Ni合金层稳定存在于Ni基高温合金（或Hastelloy X）和含1250at%Al的Ni铝化物之间。结果表明，Re-Cr-Ni合金层对Al的内扩散和合金元素的外扩散起到了阻挡作用。在化学阻挡涂层中，最外层的TiAl 2和富Al的γ-TiAl外层都保持了较高的Al含量，形成了保护性的Al 2 O3膜，而内层、γ、β、Laves三相混合层抑制了合金基体与外层/最外层之间的相互扩散。
To suppress interdiffusion between the coating and alloy substrate in addition to ensuring slow oxide growth at very high temperatures advanced coatings were developed, and they were classified into four groups, (1) the diffusion barrier coating with a duplex layer structure, an inner σ−(Re-Cr-Ni) phase as a diffusion barrier and outer Ni aluminides as an aluminum reservoir formed on a Ni based superalloy, Hastelloy X, and Nb-based alloy. (2) the up-hill diffusion coating with a duplex layer structure, an inner TiAl2 + L12 and an outer β-NiAl formed on TiAl intermetallic and Ti-based heat resistant alloys by the Ni-plating followed by high Al-activity pack cementation. (3) the chemical barrier coating with a duplex layer structure, an inner* γ + β + Laves three phases mixture as a chemical diffusion barrier and an outer Al-rich γ-TiAl as an Al reservoir formed by the two step Cr / Al pack process. (4) the self-formed coating with the duplex structure, an inner α-Cr layer as a diffusion barrier and an outer β-NiAl as an Al-reservoir on Ni-(2050)at% Cr alloy changed from the δ-Ni2Al3 coating during oxidation at high temperature. The oxidation properties of the coated alloys were investigated at temperatures between 1173 and 1573K in air for up to 1,000 hrs (10,000 hrs for the up-hill diffusion coating). In the diffusion barrier coating the Re-Cr-Ni alloy layer was stable, existing between the Ni-based superalloy (or Hastelloy X) and Ni aluminides containing 1250at%Al when oxidized at 1423K for up to 1800ks. It was found that the Re-Cr-Ni alloy layer acts as a diffusion barrier for both the inward diffusion of Al and outward diffusion of alloying elements in the alloy substrate. In the chemical barrier coating both the TiAl2 outermost and Al-rich γ-TiAl outer layers maintained high Al contents, forming a protective Al2O3 scale, and it seems that the inner, γ, β, Laves three phase mixture layer suppresses mutual diffusion between the alloy substrate and the outer/outermost layers.