The Effect of Graphite Particles as Lubricant Additive on the Friction and Wear Behaviour of AISI H11 Steel

Abstract

In recent years, the tribological investigations have been focused on dispersing additives into the oil lubricants to improve their friction and wear properties. Microhardness measurements of the samples made from heat treated hot work tool steel were carried out in this study. The wear and friction behaviour of the samples were investigated under dry condition, base oil and 5%, 10%, 15%, 20% and 25% wt. graphite as oil additive. Wear tests were carried out by means of a ball-on-disc test configuration. Average friction coefficients and wear scar related wear rates were calculated. The morphology of the worn surfaces were analyzed by optical microscopy and scanning electron microscopy (SEM). The study leads to the conclusion that addition of graphite particles improved the wear and friction properties of the lubricant. 5% graphite dispersed oil additive exhibited the best tribological performance in the tests.

Keywords

• wear
• friction
• graphite
• lubricant additive
• AISI H11

Grafit Partiküllerinin Yağ Katkısı Olarak AISI H11 Çeliğinin Sürtünme ve Aşınma Davranışı Üzerine Etkisi

Abstract

Son yıllarda tribolojik araştırmalar yağlara katkılar ekleyerek onların sürtünme ve aşınma özelliklerini iyileştirmek üzerine yoğunlaşmıştır. Bu çalışmada, ısıl işlem uygulanmış sıcak iş takım çeliği malzemeden numunelerin kuru koşul, katkısız yağ ve ağırlıkça %5, %10, %15, %20 ve %25 grafit katkılı yağlarda aşınma ve sürtünme özellikleri incelenmiştir. Aşınma deneyleri ball-on-disc deney düzeneği ile gerçekleştirilmiştir. Ortalama sürtünme katsayıları ve aşınma izlerine bağlı olarak aşınma oranları hesaplanmıştır. Mikrosertlik ölçümleri yapılan numunelerin optik mikroskop ve taramalı elektron mikroskobu (SEM) ile aşınan yüzeylerinin mikroyapı analizleri yapılmıştır. Çalışmada sonuç olarak, grafit partiküllerinin yağın aşınma ve sürtünme özelliklerini iyileştirdiği görülmüştür. Deneylerde en iyi tribolojik performansı %5 grafit katkılı yağ sergilemiştir.

Keywords

• aşınma
• sürtünme
• grafit
• yağ katkısı
• AISI H11

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