Plazma nitrürlenmiş, PVD kaplanmış ve çift yüzey işlemi uygulanmış sıcak iş takım çeliklerinin aşınma davranışlarının araştırılması
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Date
2011-07-27
Authors
Tutar, Mümin
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Publisher
Uludağ Üniversitesi
Abstract
Bu çalışmada; AISI H13 ve ASSAB patenti iki farklı sıcak iş takım çeliği seçilmiş ve bu çeliklere uygulanan ıslah etme, plazma nitrürleme (PN), PVD (Physical Vapour Deposition ( Fiziksel Buhar Biriktirme) kaplama, PN+PVD kaplama işlemleri sonucu elde edilen yüzey özellikleri deneysel olarak incelenmiştir.Numuneler ıslah edilmiş ve PN işlemi uygulanmıştır. PN parametreleri; 500 oC sıcaklık, 10 saat süre, gaz ve gaz oranları olarak ¼ (H2/N2) ve 250 Pa basınç değerleri seçilmiştir. PN işleminin öncesinde ve sonrasında işlemlerin pürüzlülüğe etkisini görmek için zımparalama ve parlatma işlemleri ile yüzey pürüzlülüğü azaltılmıştır. Bir kısım numune ıslah sonrası direkt olarak, bir kısım numune de PN sonrası PVD yöntemiyle CrN ve TiAlN kaplanmıştır. Uygulanan işlemlerin meydana getirdiği yapıların yüzey sertlikleri ve sertlik dağılımları mikrovickers sertlik ölçüm cihazı ile ölçülmüş, pürüzlülük ölçüm cihazı ile yüzey pürüzlülükleri ölçülmüş; ball on disk aşınma test cihazı ile sürtünme katsayılarının değişimleri incelenmiş, optik mikroskop ile mikro yapılar ve aşınma izleri incelenmiştir.Deney sonuçlarının karşılaştırmalı değerlendirilmesi sonucu; PN üzerine PVD kaplamanın, ıslah üzerine PVD kaplamaktan daha pürüzlü yüzeyler oluşturduğu tespit edilmiştir. CrN kaplama TiAlN kaplamadan daha düşük pürüzlülük değerleri göstermiş ancak daha yüksek sürtünme katsayılarıyla daha fazla aşınma göstermiştir.Q grubu numunelerde PN üzerine PVD kaplamanın ıslah üzerine kaplamaya göre sürtünme katsayısının daha yüksek olduğu, S grubu numunelerde ise PN üzerine PVD kaplamaların sürtünme katsayısının daha düşük olduğu gözlenmiştir.Plazma nitrürlemenin her iki numunede de sürtünme katsayısını düşürdüğü ve aşınmayı azalttığı görülmüştür.Q kodlu numunelerin ıslah sonrası daha ince tanelere, PN sonrası daha yüksek sertliklere sahip olduğu ve deneylerde daha düşük sürtünme katsayıları gösterdiği tespit edilmiştir.
In this study, two different hot work tool steels with patented under the name of AISI H13 and ASSAB were choosen and surface properties of these steels resulting from tempering, Plasma Nitriding (PN), Physical Vapour Deposition (PVD) coating and PN+PVD coating (duplex) were experimentally investigated.Samples were tempered and then plasma nitriding was performed for all samples. The plasma nitriding processes of all samples were carried out at 500 oC for 10 hours using the mixed nitrogen and hydrogen at a volume ratio of 4:1 as the source gas at a total pressure of 250 Pa. Before and after plasma nitriding processes, the surface roughness of the samples was reduced with grinding and polishing to determine the effect of heat treatments and coatings on surface roughness. A group of samples were directly CrN and TiAlN coated with PVD technique after tempering while the other group were CrN and TiAlN coated with PVD technique after PN. Surface hardnesses and hardness profiles of all samples were performed on a Vickers microhardness tester, the surface roughness of the samples were measured by using stylus profilometer, friction characteristics of all samples were evaluated on a wear tester in a ball-on-disc contact configuration, which allows the determination of the friction coefficient, and the morphologies of the surfaces and worn surfaces of the samples were observed using an optical microscope.The experimental results indicated that; PVD coating on plasma nitrided samples increased the surface roughness with respect to PVD coating on only tempered samples.CrN coating exhibited the lower surface roughess values compared to TiAlN coating, but the wear loss of CrN coated samples increased depending on the higher friction coefficient. In Q group of the samples, PVD coating on plasma nitrided samples had the higher friction coefficient with respect to PVD coating on only tempered samples, whereas in S group of the samples, the lower friction coefficients were observed on PVD coating on plasma nitrided samples.PN reduced the wear loss and the friction coefficient of both groups of the samples.Q coded samples had finer grains following tempering, and the higher hardness values and the lower friction coefficients following PN.
In this study, two different hot work tool steels with patented under the name of AISI H13 and ASSAB were choosen and surface properties of these steels resulting from tempering, Plasma Nitriding (PN), Physical Vapour Deposition (PVD) coating and PN+PVD coating (duplex) were experimentally investigated.Samples were tempered and then plasma nitriding was performed for all samples. The plasma nitriding processes of all samples were carried out at 500 oC for 10 hours using the mixed nitrogen and hydrogen at a volume ratio of 4:1 as the source gas at a total pressure of 250 Pa. Before and after plasma nitriding processes, the surface roughness of the samples was reduced with grinding and polishing to determine the effect of heat treatments and coatings on surface roughness. A group of samples were directly CrN and TiAlN coated with PVD technique after tempering while the other group were CrN and TiAlN coated with PVD technique after PN. Surface hardnesses and hardness profiles of all samples were performed on a Vickers microhardness tester, the surface roughness of the samples were measured by using stylus profilometer, friction characteristics of all samples were evaluated on a wear tester in a ball-on-disc contact configuration, which allows the determination of the friction coefficient, and the morphologies of the surfaces and worn surfaces of the samples were observed using an optical microscope.The experimental results indicated that; PVD coating on plasma nitrided samples increased the surface roughness with respect to PVD coating on only tempered samples.CrN coating exhibited the lower surface roughess values compared to TiAlN coating, but the wear loss of CrN coated samples increased depending on the higher friction coefficient. In Q group of the samples, PVD coating on plasma nitrided samples had the higher friction coefficient with respect to PVD coating on only tempered samples, whereas in S group of the samples, the lower friction coefficients were observed on PVD coating on plasma nitrided samples.PN reduced the wear loss and the friction coefficient of both groups of the samples.Q coded samples had finer grains following tempering, and the higher hardness values and the lower friction coefficients following PN.
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Keywords
Plazma nitrürleme, PVD kaplama, Pürüzlülük, Sertlik, Aşınma, Plazma nitrürleme, PVD kaplama, Pürüzlülük, Sertlik, Aşınma, PVD coating, Roughness, Hardness, Wear, Plasma nitriding
Citation
Tutar, M. (2011). Plazma nitrürlenmiş, PVD kaplanmış ve çift yüzey işlemi uygulanmış sıcak iş takım çeliklerinin aşınma davranışlarının araştırılması. Yayınlanmamış yüksek lisans tezi. Uludağ Üniversitesi Fen Bilimleri Enstitüsü.