Termoreaktif difüzyon yöntemiyle niyobyum karbür-bor (nbc-b) kaplanan hardox 400 çeliğin mikroyapı özelliklerinin incelenmesi ve taguchi yöntemiyle aşınma davranışının değerlendirilmesi
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Tarih
2021-01-14
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Batman Üniversitesi Fen Bilimleri Enstitüsü
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info:eu-repo/semantics/openAccess
Attribution-ShareAlike 3.0 United States
Attribution-ShareAlike 3.0 United States
Özet
Genel olarak çelik malzemelerin mekanik etkiler sonucunda kullanım dışı kalarak ülke ekonomisinde yüksek hasarlara sebebiyet verdiği bilinmektedir. Hem aşınma hem de korozyon gibi etkileşimlerin yol açtığı kayıplar ülke ekonomisine zarar verdiğinden, akademik ve sanayi toplulukları harekete geçmiş ve aşınma özellikleri açısından güçlü malzemeler aramaya başlamışlardır. Dolayısıyla sanayide sıklıkla kullanılan çelik malzemelere difüzyon, kimyasal çökeltme ve fiziksel çökeltme kaplama yöntemleri uygulanmaya başlanmıştır.
Bu tez çalışmasında, altlık malzeme amacıyla yararlanılan Hardox 400 çeliği, katı ortam Termoreaktif Difüzyon (TRD) yöntemi ile karbür yapıcı element tozlarından Ferro Niyobyum ve Ferro Bor tozları kullanılarak kaplanmıştır. Kaplama işlemi üç farklı sıcaklık (950, 1000 ve 1050 °C) ve üç farklı zaman aralığında (1, 2 ve 3 saat) gerçekleştirilmiştir. TRD yöntemiyle kaplama işlemi gerçekleştirilen her bir parametre sonrasında numunelerin optik mikroskop, Taramalı Elektron Mikroskobu (SEM), Enerji Dağılımlı X-Işını Spektrometresi (EDX) ve X-Işını Kırınımı (XRD) ile mikroyapıları incelenmiş ve kaplama yüzeylerindeki sertlik değerleri ölçülmüştür. Kaplama parametrelerinin kaplama kalınlığına ve sertliğe etkileri analiz edilmiştir. Ayrıca sertliğin ve kaplama parametrelerinin aşınmaya etkisini tespit etmek için numuneler aşınma testlerine tabi tutulmuştur. Aşınma deneylerinde, Taguchi deney tasarım düzeneğinden faydalanılmıştır. Elde edilen sonuçlar mevcut şartlarda kullanılan Hardox 400 çeliği ile kıyaslanmıştır.
Kaplama parametrelerine bağlı olarak Hardox 400 çelik yüzeyinin TRD yöntemiyle kaplana bildiği, kaplama sıcaklığı ve süresinin artmasıyla kaplama kalınlıklarının arttığı optik mikroskop ve SEM görüntülerinden görülmüştür. Minimum kaplama kalınlığı, 950 °C kaplama sıcaklığı ile 1 saat süreyle kaplanan numunelerde, maksimum kaplama kalınlığı ise 1050 °C kaplama sıcaklığı ile 3 saat süreyle kaplanan numunelerde oluşmuştur. Kaplama tabakasının B, C, Fe ve Nb elementlerinden oluştuğu EDX analizinden, kaplama tabakasındaki fazın NbC-B olduğu XRD analizinden gözlemlenmiştir. NbC-B fazının
iv
sertliğinin artmasında önemli bir faktör olduğu, dolayısıyla kaplama sıcaklığı ve süresinin artmasıyla sertliğin arttığı tespit edilmiştir. Maksimum sertlik, 1050 °C’de 3 saat süreyle kaplanan numunede 2934,2 HV ölçülmüştür. Aşınma deneylerinde ise aşınma hacminin kaplama sıcaklığının 950 °C’den 1000 °C’ye çıkmasıyla azaldığı, 1000 °C’den 1050 °C’ye çıkmasıyla çok az da olsa artmaya başladığı görülmüştür. Benzer durum kaplama süresi için de söz konusudur. Uygulanan yükün artması, aşınma hacmini arttırmıştır. Taguchi yöntemine göre 1000 °C’de 2 saat süreyle kaplanan numunenin 5 N’luk yük altındaki aşınması minimum, 950 °C’de 3 saat süreyle kaplanan numunenin 15 N’luk yük altındaki aşınması maksimumdur. Minimum ve maksimum aşınma hacimleri yaklaşık 0,063 mm3 ve 0,328 mm3’tür. Kaplanmış Hardox 400 çelikleri ile karşılaştırıldığında, genel olarak kaplanmamış Hardox 400 çelikleri daha fazla aşınmıştır. Ancak 10 N ve 15 N’luk uygulama yüklerinde, 3 saat süreyle 950 °C ve 1050 °C’de kaplanan numunelerin daha fazla aşındığı görülmüştür. Bunun, kaplama tabakası altında bulunan gözenekli yapının aşınma deneyleri esnasında plastik deformasyondan kaynaklı kırılmaya sebebiyet vermesinden kaynaklandığı düşünülmektedir.
In general, it is known that steel materials are out of use because of mechanical effects and cause high damage in the country’s economy. Because the losses caused by interactions such as both wear and corrosion have caused to damage to the country’s economy, the academic and industry communities have taken action and they have started to search for strong materials in terms of hardness and wear properties. Therefore, diffusion, chemical deposition, and physical deposition coating methods have begun to apply to steel materials frequently used in the industry. In this thesis study, Hardox 400 steel used as substrate material has been coated with solid media Thermoreactive Diffusion (TRD) method using Ferro Niobium and Ferro Boron powders from carbide forming element powders. Coating has been carried out in three different temperatures (950, 1000 and 1050 °C) and three different time intervals (1, 2 and 3 hours). After each parameter of coating process carried out by TRD method, microstructures of specimens have been examined by optical microscope, Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDX) and X-Ray Diffraction (XRD) and hardness values on the coating surfaces have been measured. The effects of coating parameters on coating thickness and hardness have been analysed. In addition, specimens have been subjected to wear tests to determine the effect of hardness and coating parameters on wear. In the wear tests, the Taguchi test design setup has been benefited. The obtained results have been compared with the Hardox 400 steel used under current conditions. It has been seen from optical microscope and SEM images that Hardox 400 steel surface could be coated with TRD method depending on coating parameters, and coating thickness has increased with increasing coating temperature and time. Minimum coating thickness was formed in samples coated with coating temperature of 950 °C for 1 hour, while maximum coating thickness was formed in samples coated with coating temperature of 1050 °C for 3 hours. EDX analysis have showed that the coating layer is composed of B, C, Fe and Nb elements and XRD analysis also have showed that the phase in the coating vi layer is NbC-B. The NbC-B phase has been determined to be an important factor in increasing the hardness, hence the hardness has increased with the increase of the coating temperature and time. Maximum hardness, 2934.2 HV was measured on the sample coated at 1050 °C for 3 hours. In the adhesive wear experiments, it was observed that the wear volume decreased when the coating temperature increased from 950 °C to 1000 °C and started to increase slightly when it increased from 1000 °C to 1050 °C. A similar situation is also valid for the coating time. The increase of the applied load has increased wear volume. According to the Taguchi method, the wear volume of the sample coated at 1000 °C for 2 hours is minimum and the wear volume of the sample coated at 950 °C for 3 hours is maximum. Minimum and maximum wear volumes are approximately 0.063 mm3 and 0.328 mm3. In general, uncoated Hardox 400 steels have been more worn out compared to coated Hardox 400 steels. The samples coated at 950 °C and 1050 °C for 3 hours has more worn out at application loads of 10 N and 15 N. This is thought to be due to the porous structure under the coating layer causing breakage due to plastic deformation during wear tests.
In general, it is known that steel materials are out of use because of mechanical effects and cause high damage in the country’s economy. Because the losses caused by interactions such as both wear and corrosion have caused to damage to the country’s economy, the academic and industry communities have taken action and they have started to search for strong materials in terms of hardness and wear properties. Therefore, diffusion, chemical deposition, and physical deposition coating methods have begun to apply to steel materials frequently used in the industry. In this thesis study, Hardox 400 steel used as substrate material has been coated with solid media Thermoreactive Diffusion (TRD) method using Ferro Niobium and Ferro Boron powders from carbide forming element powders. Coating has been carried out in three different temperatures (950, 1000 and 1050 °C) and three different time intervals (1, 2 and 3 hours). After each parameter of coating process carried out by TRD method, microstructures of specimens have been examined by optical microscope, Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDX) and X-Ray Diffraction (XRD) and hardness values on the coating surfaces have been measured. The effects of coating parameters on coating thickness and hardness have been analysed. In addition, specimens have been subjected to wear tests to determine the effect of hardness and coating parameters on wear. In the wear tests, the Taguchi test design setup has been benefited. The obtained results have been compared with the Hardox 400 steel used under current conditions. It has been seen from optical microscope and SEM images that Hardox 400 steel surface could be coated with TRD method depending on coating parameters, and coating thickness has increased with increasing coating temperature and time. Minimum coating thickness was formed in samples coated with coating temperature of 950 °C for 1 hour, while maximum coating thickness was formed in samples coated with coating temperature of 1050 °C for 3 hours. EDX analysis have showed that the coating layer is composed of B, C, Fe and Nb elements and XRD analysis also have showed that the phase in the coating vi layer is NbC-B. The NbC-B phase has been determined to be an important factor in increasing the hardness, hence the hardness has increased with the increase of the coating temperature and time. Maximum hardness, 2934.2 HV was measured on the sample coated at 1050 °C for 3 hours. In the adhesive wear experiments, it was observed that the wear volume decreased when the coating temperature increased from 950 °C to 1000 °C and started to increase slightly when it increased from 1000 °C to 1050 °C. A similar situation is also valid for the coating time. The increase of the applied load has increased wear volume. According to the Taguchi method, the wear volume of the sample coated at 1000 °C for 2 hours is minimum and the wear volume of the sample coated at 950 °C for 3 hours is maximum. Minimum and maximum wear volumes are approximately 0.063 mm3 and 0.328 mm3. In general, uncoated Hardox 400 steels have been more worn out compared to coated Hardox 400 steels. The samples coated at 950 °C and 1050 °C for 3 hours has more worn out at application loads of 10 N and 15 N. This is thought to be due to the porous structure under the coating layer causing breakage due to plastic deformation during wear tests.
Açıklama
Anahtar Kelimeler
Aşınma, Ferro Bor, Ferro Niyobyum, Hardox 400 Çeliği, Mikroyapı, Sertlik, Taguchi Yöntemi, Termoreaktif Difüzyon Yöntemi, Ferro Boron, Ferro Niobium, Hardness, Hardox 400 Steel, Nb Coating, Microstructure, Taguchi Method, Thermoreactive Diffusion Method, Wear
Kaynak
WoS Q Değeri
Scopus Q Değeri
Cilt
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Künye
Ertem, M.(2021). Termoreaktif difüzyon yöntemiyle niyobyum karbür-bor (nbc-b) kaplanan hardox 400 çeliğin mikroyapı özelliklerinin incelenmesi ve taguchi yöntemiyle aşınma davranışının değerlendirilmesi. (Yayınlanmamış Yüksek Lisans Tezi). Batman Üniversitesi Fen Bilimleri Enstitüsü, Batman.