This impervious layer or boundary will retard the free diffusion of moisture. This condition is referred to as case hardening.

这一不透气的壳层(或边界层)会阻滞水分自由扩散，这种情形称为表面硬化。

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The paper also briefs the nozzle or moving blade surface hardening treatment technology, including plasma spraying and diffusion layer for preventing the nozzle and moving blade from SPE.

文章还介绍了为预防汽轮机喷嘴和动叶片免受固体颗粒侵蚀所采用的表面硬化处理技术，包括等离子喷涂层和扩散渗层在内；

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