Surface Modification of Light Alloys Exposed to Excessive Conditions in the Defense Industry

Yıl 2019, , 67 - 90, 06.11.2019

Hayrani Ulutürk Uğur Malayoğlu Kadir Cihan Tekin

https://doi.org/10.17134/khosbd.642140

Öz

In this study, ceramic coatings were developed
on AA7075 alloy by plasma electrolytic oxidation (PEO) method in different
solutions prepared by adding aluminum oxide, silicon oxide, wolfram-titanium
carbide and titanium carbide particles. The phase composition of the coatings
was investigated by x-ray diffraction (XRD) method. The surface morphology of
the coatings and the microstructure of the cross-section were investigated by
scanning electron microscopy (SEM). Chemical analyzes of the coatings were made
by means of energy distribution x-ray spectrometry (EDX). The hardness values
of the coatings were measured by microVickers hardness tester. In order to
examine the friction and wear behavior of the coated substrates, dry sliding
wear tests were performed against 100Cr6 steel and alumina balls. After the
wear test, the wear profile was obtained by the surface profilometer and the
material volume loss was calculated. As a result of the tests, it has been
observed that the surface hardness and wear resistance of the AA7075 alloy was
significantly increased by the application of PEO coatings. The
coatings consist of a dense inner layer and a porous outer layer. It has been
determined that the coating hardness increased close to substrate/coating
interface while decreasing towards the free surface due to the increased
porosity. The coatings produced in silicon oxide particle-containing solutions
were found to be thicker and rougher than the other coatings. The lowest wear
loss was obtained in the coating produced in titanium-carbide-containing
solutions.

Anahtar Kelimeler

AA7075, Plasma Electrolytic Oxidation, Nanoparticle, Hardness, Wear

Savunma Sanayisinde Aşırı Koşullara Maruz Kalan Hafif Yapısal Malzemelerin Yüzey Modifikasyonu

Öz

Bu çalışmada, alüminyum
oksit, silisyum oksit, wolfram-titanyum karbür ve titanyum karbür parçacıklar
ilave edilerek hazırlanan çözeltilerde, plazma elektrolitik oksidasyon (PEO)
yöntemiyle AA7075 alaşımı üzerine seramik kaplamalar geliştirilmiştir. Kaplamaların
faz bileşimi x-ışını kırınımı (XRD) yöntemiyle incelenmiştir. Taramalı elektron
mikroskobu (SEM) ile kaplamaların yüzey morfolojisi ve kesitin mikroyapısı
incelenmiştir. Enerji dağılımlı x-ışını spektrometresi (EDX) sayesinde
kaplamaların kimyasal analizi yapılmıştır. Kaplamaların sertlik değerleri
mikroVickers sertlik test cihazıyla ölçülmüştür. Kaplama yapılan altlık
alaşımların sürtünme ve aşınma davranışını incelemek amacıyla 100Cr6 çelik ve
alüminyum oksit bilyelere karşı kuru kaymalı aşınma testleri yapılmıştır.
Aşınma testi sonrası yüzey profilometresiyle aşınma profili çıkarılarak aşınan
malzeme hacmi hesaplanmıştır. Yapılan testler sonucunda AA7075 alaşımın yüzey
sertliği ve aşınma dayanımının üretilen PEO kaplamalarla önemli ölçüde arttığı
gözlenmiştir. Kaplamalar yoğun iç tabaka ve gözenekli üst tabakadan
oluşmaktadır. Kaplama sertliğinin altlık/kaplama arayüzeyine yakın bölgede
yüksek, yüzeye doğru ilerledikçe gözenekliliğin artışından dolayı düştüğü
belirlenmiştir. Silisyum oksit parçacık içeren çözeltilerde üretilen
kaplamaların diğer kaplamalara göre daha kalın ve pürüzlü olduğu tespit
edilmiştir. En düşük aşınma kaybı titanyum karbür içeren çözeltilerde üretilen
kaplamada elde edilmiştir.

Anahtar Kelimeler

AA7075, Plazma Elektrolitik Oksidasyon, Nanoparçacık, Sertlik, Aşınma

Kaynakça

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