Nitrürlenmiş 7075-T6 alüminyum alaşımının vakum ve atmosfer şartlarında sürtünme ve aşınma özelliklerinin incelenmesi

Öz

Al7075 alaşımları, otomotiv endüstrisinde, askeri araçların ve uçakların bileşenlerinde, kauçuk ve plastik kalıplarda yaygın olarak kullanılmaktadır. Ayrıca, benzer Al alaşımları, uzay araştırmalarında mekanik parçalar için sıklıkla kullanılmaktadır. Bu nedenle, vakum altında aşınma özelliklerinin incelenmesi, atmosfer ortamındaki aşınma özellikleri kadar vazgeçilmezdir. Ancak söz konusu alaşımların aşınma performansı beklentileri karşılayamamaktadır. Bu bağlamda, bu çalışmada nitrürlenmiş Al7075-T6'nın atmosfer ve vakum ortamlarında aşınma özelliklerinin belirlenmesi amaçlanmıştır. Oluşturulan AlN tabakasının yüzey karakterizasyonu ve faz analizi, taramalı elektron mikroskobu, enerji dağıtıcı X-ışını spektrometresi, 3D optik profilometre ve X-ışını difraktometresi ile belirlenmiştir. Numunelerin sertliği, Vickers mikro sertlik test cihazı kullanılarak belirlenmiştir. Numunelerin aşınma performansı, bilye disk esaslı aşınma test cihazı kullanılarak atmosfer ve vakum ortamlarında incelenmiştir. Her iki koşul için de en iyi aşınma performansı nitrürlenmiş numunelerden elde edilmiştir. AlN tabakasının (0,19), ortam havası altında alt tabakanın (0,60) sürtünme katsayısını önemli ölçüde azalttığı gözlemlenmiştir. Nitrür tabakası sayesinde, alaşımın atmosfer ortamındaki aşınma direnci dikkate değer bir şekilde iyileştirilmiştir. Ayrıca aşınma oranı açısından nitrür tabakasının aşınma performansı, ortam havasında (0.00010 mm3/Nm) vakum ortamına (0.00087 mm3/Nm) göre daha iyi olduğu gözlemlenmiştir. Hatta numunelerdeki aşınma yolunun çok ince olduğu ve neredeyse fark edilemez olduğu gözlemlenmiştir.

Anahtar Kelimeler

• Al7075-T6
• Plazma nitrürleme
• Aşınma
• Vakum

Investigation of the friction and wear properties of nitrided 7075-T6 aluminum alloy under vacuum and ambient air

Abstract

Al7075 alloy is commonly used in the automotive industry, components of military vehicles and aircraft, rubber and plastic moulds. Also, similar Al alloys are frequently used for mechanical parts in space exploration. Therefore, investigation of the wear properties under a vacuum environment is as indispensable as wear properties under an atmosphere. However, the wear performance of this alloy cannot meet the expectations. This paper reports the investigation of the obtained wear properties of Al7075-T6 alloy after plasma nitriding in ambient air and vacuum environments. The surface characterization and phase analysis of the formed AlN layers are determined by scanning electron microscope, energy dispersive X-ray spectrometer, 3D optical profilometer and X-ray diffractometer. The hardness of the nitride layer is established using Vickers micro-hardness tester. The wear performance of the untreated and nitride sample is investigated under 1N constant load at ambient air and vacuum environment. As a result of wear tests, the best wear performance of both conditions has been obtained from nitrided samples. The AlN layer (0.19) is observed to notably reduced the coefficient of friction of the substrate (0.60) under ambient air. Besides, it is observed that the nitride layer is better in ambient air (0.00010 mm3/Nm) than in vacuum environment (0.00087 mm3/Nm) in term of wear rate. In fact, the wear track on the nitrided sample is very thin under ambient air, and nearly imperceptible.

Keywords

• Al7075-T6
• Plasma Nitriding
• Wear
• Vacuum

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