تأثیر عملیات نیتراسیون بر ساختار، سختی سطح و رفتار سایشی فولاد 4140 پوشش داده شده به روش الکترولسNi-P
نویسنده
چکیده
(2 میکرون) دارد به طوری‌که انجام این عملیات می‌تواند موجب توسعه نوعی پوشش چند جزیی حاوی فازهای بین فلزی، فسفید و نیترید به همراه منطقه محدود نفـوذی در سطـح فولاد حاوی پوشش نازک Ni-P(با ضخامت 2 میکرون) شود. این فولاد تحت نیروی بالاتر سایش، مقاومت سایشی بهتری نسبت به فولاد حاوی پوشش ضخیمتر(24 میکرون) از خود ارایه داد. رفتار مذکور به تشکیل فازهای نیتریدی در سطح و نیز ایجاد ناحیه متأثر از نفوذ نیتروژن در زیر سطح فولاد اخیر نسبت داده شد.
کلیدواژه‌ها
عنوان مقاله [English]
Effect of Thermochemical Treatment on The Structure, Hardness and Wear Behavior of Electrolss Ni-P Coated 4140 Steel
نویسنده [English]
- K. Zangeneh Madar and S. M. Monir Vaghefi
In the present stady, thermochemical treatment in H2/NH3 atmosphere was used as a post-treatment for electroless Ni-P coatings on the AISI 4140 steel substrates. High phosphorus (9%) coatings with thicknesses of 2, 24 and 48 m were applied and the effects of the thermochemical treatment on the morphology, structural changes, roughness, hardness
and wear resistance of coatings were studied by SEM, EDS, XRD, profilometry, and microhardness tester. Wear test was used to evaluate wear characteristics of coatings. The wear behaviour of the thermochemical treated/Ni-P coated samples was assessed by comparison with thermochemical treated/uncoated (nitrided) samples. The results showed that effect of thermochemical treatment varies with the coating thickness. In addition, it was shown that a multicomponent coating containing phosphide, nitride and intermetallic phases as well as diffusion region can be developed in the thin (2 m) electroless Ni-P coated steel by thermochemical treatment. This sample showed better wear resistance than 24 m Ni-P coated steel under higher load. This behavior was ascribedto nitride phases formed at the surface as well as a nitrogen diffusion zone at the subsurface of thin Ni-P coated steel
کلیدواژه‌ها [English]
- Thermochemical treatment
- Thin Ni-P coating
- Wear behavior
- Diffusion zone
)