Halid Aktive Edilmiş Kutu Sementasyon Yöntemi İle Paslanmaz Çeliğin Yüzey Modifikasyonunun Modellenmesi

Yüksek sıcaklık uygulamalarında demir esaslı malzemeler, beklenen mekanik özellikler, üretim kolaylığı, oda sıcaklığı korozyon direnci ve maliyet etkinliğinin kombinasyonlarından dolayı önemlidir. Fakat mekanik özellikler, çevresel etkilere karşı optimize edilmelidir. Endüstriyel uygulamaya bağlı olarak çeşitli korozyon türleri oluşabilir. Korozyona karşı korunurken yapısal alaşımın mekanik özelliklerinin de korunmasına yönelik bir yaklaşım, koruyucu kaplamaların uygulanmasıdır. Difüzyon kaplamaları, zararlı yüksek sıcaklık koşullarına karşı korozyon, oksidasyon, aşınma direncinin elde edilmesinde etkili bir yöntemdir. Literatürlere göre, halid aktive edilmiş kutu sementasyon yöntemi, demir esaslı malzemeler için uzun süredir yaygın olarak kullanılmaktadır. Bununla birlikte, kaplama uygulamalarının geliştirilmesi ile ilgili çalışmaların çoğu, mikroskobik, kimyasal ve mekanik analizleri içeren deneysel araştırmalara dayanmaktadır. Hesaplamalı alaşım yaklaşımlarına dayalı sınırlı çalışmalar yapılmıştır. Bu çalışmada, AISI 316L çeliğinin halid aktive edilmiş kutu sementasyonu ile Cr kaplanması bir difüzyonel problem olarak ele alınmış olup, kaplama kinetiği simülasyon çalışmaları ile incelenmiştir. Proses değişkenlerinin etkileri ve yüzeyde oluşturacakları kaplama tabaka bileşimleri termodinamik olarak Thermo-Calc ve kinetik olarak DICTRA ile modellenmiştir. Bu yaklaşım katı hal difüzyonlarının proses parametrelerine bağımlılığını ve kaplama ve altlık malzemesi boyunca oluşan fazların daha iyi anlaşılmasını sağlar.

Anahtar Kelimeler:

Yüzey modifikasyonu, Kutu sementasyonu, Thermo-Calc, DICTRA

Modeling of Surface Modification of Stainless Steel by Halide Activated Pack Cementation Method

In high-temperature applications, ferrous-based materials are important due to their excellent combination of desirable mechanical properties, ease of production, corrosion resistance at room temperature and cost-effectiveness. However, mechanical properties must be optimized against environmental effects. Depending on the industrial applications, various corrosion types may also occur. An approach to preserve the mechanical properties of the structural alloy being protected against corrosion is the application of protective coatings to the surfaces. Diffusion coatings are an effective method to obtain corrosion, oxidation and abrasion resistance against detrimental conditions of high temperature. According to the literature, the halide activated pack cementation method has been widely used for ferrous-based materials for a long time. However, most studies concerned with developing coating applications are based on experimental investigations that include microscopic, chemical, and mechanical analyses. Limited studies have been conducted based on computational alloy approaches. In this study, Cr coating of the AISI 316L steel by halide activated pack cementation method was considered as a diffusional problem and the kinetics of the coating deposition process were examined. The effect of process variables such as temperature, time and the compositions of coating layers formed on the surfaces were investigated thermodynamically with Thermo-Calc software and kinetically with DICTRA module. This approach provides insight into the dependence of solid-state diffusions on the processing parameters, and a better understanding of the phases that form along the coating and substrate material.

Keywords:

Surface modification, Pack cementation, Thermo-Calc, DICTRA,

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