The Effect of CeO2 Nanoparticles Addition to PEO Coatings on Corrosion Behavior

Öz

Plasma Electrolytic Oxidation (PEO) is a coating technique commonly chosen to improve the corrosion and wear properties of Mg and its alloys. Besides, the limited phase composition and porous structure of the PEO coating layer influence negatively the long-term objective of corrosion protection.  In recent years, the technique filing the micro or nano-sized particles into porous oxide layer during coating process is a novel approach for PEO. This investigation focuses on how surface morphology, microstructure, phase composition and corrosion behavior of incorporation of particles into PEO coatings on AZ31 magnesium alloy. This study aims at growth MgO/CeO2 nanocomposite coatings by using PEO technique in the electrolyte containing nano-sized cerium oxide (CeO2) particles on MgAZ31 substrate. The structural properties, surface morphology, coating thickness and corrosion behavior of the coatings grown in electrolyte containing different amounts of CeO2 nanoparticles were compared with the particle-free PEO coating. The research results showed that the nanoparticles could not completely fill the dense porous structure of the PEO coatings, reduced the coating growth rate and that the CeO2 nanoparticles are incorporated into the structure as inert. In addition, it is determined that the corrosion resistance of MgO/CeO2 nanocomposite coatings is higher than MgO coatings without particle.

Anahtar Kelimeler

• Mg AZ31,plasma electrolytic oxidation,CeO2,corrosion

PEO Kaplamalara CeO2 Nanopartikül İlavesinin Korozyon Davranışına Etkisi

Öz

Endüstriyel bir yüzey modifikasyon işlemi olarak bilinen Plazma Elektrolitik Oksidasyon (PEO) yöntemi; Mg ve alaşımlarının korozyon ve aşınma özelliklerinin iyileştirilmesinde çoğunlukla tercih edilen bir kaplama tekniğidir. Bununla birlikte, PEO kaplama tabakasının sınırlı faz kompozisyonu ve gözenekli yapısı uzun vadede korozyondan koruma hedefini olumsuz yönde etkilemektedir. Oksit tabakasının büyümesi esnasında oluşan gözeneklerin mikro veya nano boyutlu partiküllerle doldurulması tekniği son yıllarda PEO işlemine yeni bir yaklaşım kazandırmıştır. Bu sayede partiküller yardımıyla kusurların kapatılabileceği ve üretilen kaplamaların kompozisyon aralığı ve işlevselliğinin arttırılabileceği düşünülmektedir. Bu çalışma; magnezyum alaşımı üzerine büyütülen PEO kaplamalara partikül ilavesinin yüzey morfolojisine, mikro yapıya, faz kompozisyonuna ve korozyon davranışına nasıl etki edeceği araştırması üzerine odaklanmıştır.  Bu amaç doğrultusunda çalışma MgAZ31 taban malzemesi üzerine PEO yöntemi ile nano boyutlu seryum oksit (CeO2) partikülleri içeren MgO/CeO2 nanokompozit kaplamaların büyütülmesini hedeflemiştir. Farklı miktarlarda CeO2 nano partikül içeren elektrolit içerisinde büyütülen kaplamaların yapısal özellikleri, yüzey morfolojisi, kaplama kalınlıkları ve korozyon davranışı partikülsüz PEO kaplaması ile karşılaştırılmıştır. Araştırma sonuçları nano partiküllerin PEO kaplamaların yoğun gözenekli yapısını tamamen dolduramadığını, kaplama büyüme hızını azalttığını ve CeO2 nano partiküllerin yapı içerisine inert olarak dâhil olduğunu gösterdi. Ayrıca partikül miktarına bağlı olarak MgO/CeO2 nanokompozit kaplamaların korozyon direncinin partikülsüz MgO kaplamalara göre daha yüksek olduğu tespit edildi.

Anahtar Kelimeler

• Mg AZ31,Plazma Ekeltrolitik Oksidasyon,CeO2,Korozyon

Kaynakça

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