Sert seramik kaplı malzemelerde kaplama tabakası-taban malzeme arayüzeyinin x- ışınları ince film tekniği ile karakterizasyonu
Başlık çevirisi mevcut değil.
- Tez No: 55768
- Danışmanlar: DOÇ.DR. YILMAZ TAPTIK
- Tez Türü: Yüksek Lisans
- Konular: Metalurji Mühendisliği, Metallurgical Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1996
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 62
Özet
ÖZET SERT SERAMİK KAPLI MALZEMELERDE KAPLAMA TABAKASI-TABAN MALZEME ARAYÜZEYİNİN X-ISINLARI İNCE FİLM TEKNİ?İ İLE KARAKTERİZASYONU Bu çalışmanın başlangıç bölümünde X-ışınıyla, ince tabaka faz analizleri hakkında bilgi vermek amacıyla önce klasik X-ışınları difraksiyonu konusunda bilgi verilmiş ve daha sonra ince film difraksiyonun klasik difraksiyondan farkı Bragg-Brentano ve Seeman-Bohlin geometrileri tanıtılmış ve Sabit Açılı ince Film geometrisi ile karşılaştırma yapılmıştır. Yapılan karşılaştırma esnasında ince filmlerden yeterli difraksiyon verilerinin alınabilmesi için gerekli olan geometrik faktörler de gözönüne alınarak klasik toz difraksiyon geometrilerinin neden ince film difraksiyon analizlerinde kullanılamayacağı ve sabit açılı ince film geometrisinin avantajları gösterilmiştir. Çalışmanın ilerleyen bölümlerinde kaplama tabakası-taban malzeme arayüzeyinde oluşan fazların ve değişikliklerin belirlenmesine yönelik olarak yapılmış çalışmalar literatür yardımı ile ortaya konmuş ve bu çalışmalardan elde edilen bilgilerden ve yaklaşımlardan yola çıkarak oluşturulan deney yaklaşımları ile çalışmalar gerçekleştirilmiştir. Deneysel çalışmalardan elde edilen difraksiyon paternlerinin değerlendirilmesi bu çalışmanın gerek ince film tekniğinin katkısını göstermek gerekse hangi sınırlar çerçevesinde bilgi vermek olanağına sahip olduğunun gösterilebilmesi açısından detaylı olarak gerçekleştirilmiştir.
Özet (Çeviri)
SUMMARY CHARACTERIZATION of SUBSTRATE-COATING INTERFACE of HARD CERAMIC COATED MATERİALS WITH X-RAY DIFFRACTION The phenomenon of x-ray diffraction was discovered by Bragg and Laue, and was used mainly by physicist in the early twentieth century. For the past 30 years this phenomenon has been extensively used in the engineering field as one of the most powerful nondestructive methods to measure atomic arrangements such as particle size, texture and phase analysis. The purpose of this study is to explain thin film phase analysis with x-ray diffraction. The study begins with an elementary discussion of crystal structures and x-ray diffraction. The last and main part of this study is thin film analysis with x-ray diffraction.This part describes what thin film phenomenon is. Possibility of using classical x-ray diffractometers for thin film analysis is investigated. The main difference between classical x-ray difractometers and x-ray thin film diffractometers are also examined. There are some experimental results given in the last part of the text, x-ray diffraction analysis of this examples have been done by Philips x-ray diffractometer with thin film attachment. X-rays diffract three dimensionally from the surface of a material. There is a certain penetration depth that x-rays can penetrate on material's surface. This penetration depends on the intensity of x-rays and coeffecient of mass absorbtion of material. Diffraction is achieved by the atoms in the penetration depth. The penetration depth of x-rays is inversely proportional to the capability of absorption and proportional to the intensity of x-ray beams. Moreover, the geometry of diffractometer affects the penetration depth of x-rays. For example coming beams of x-rays on sample material can be arranged with available geometry so that the distance between sample material and source is known as divergence distance and small divergence distances must be used in thin film analysis. Therefore the area of falling beams of x-rays must be as small as possible and x-rays interaction does not form a big penetration depth. But this area must be at such an optimum level so that it permits to determine diffraction and diffracted beams. In thin film analysis divergence distances must be between 8 1/6°-1/30°. Divergency angles 8 are 1/30°,1/12°, 1/6°, 1/4°, VIM1/2° and 1° and are selected according to 61 so that the equatorial irradiated length: A 173 tan 8 A=- sin 01 can be limited. The divergency angle used in this sudy was 1/30°. Another geometric effect is the angle of enterance of primary x-rays to the sample material. If the angle of enterance of primary x-rays to the sample is increased, then beams can enter to he sample more and if this angle of enterance is 90°, then x-rays penetration depth is maximum. In thin film analysis penetration depth must not be very high. The important point here is to determine the required penetration depth for thin film analysis. When the penetration depth increased it leads to intervene the patterns which are determined from thin film layer and substrate material. Due to the geometric structure of conventional x-rays diffractometers, they are not suitable for thin film analysis. In x-rays diffraction analysis, BraggrBrentano and Seeman Bohlin geometric structures are the most commonly used ones. In Bragg-Brentano geometry, the sample material rotates around its own axis with an angle of 6. The detector rotates with an angle of 29 around the sample material and counts the diffracted x-ray beams. As the sample rotates with an angle of 6, enterance angle of primary x-rays increase and penetration depth of x rays become higher. In this situation diffracted x-ray beams which are counted by detector, comes from thin film layer and also substrate material which is under the thin film layer. In Seemann-Bohlin type x-ray diffractometer geometry sample material is fixed with a proper angle. Therefore the angle between specimen and primary x-ray beams would be constant. Detector collects the diffracted x-ray beams with a scanning angle of 26. But the disadvantage of this type geometry is that the enterance angle of primary x- ray beams leads the diffraction not only in thin film layer but also in substrate material in large amounts. Thus, weaker diffraction patterns are obtained from thin film layer as compared to those of substrate material. Both classic Bragg-Brentano and Seeman Bohlin type x-ray diffractometer geometries the problem of enterance angle of primary x-rays is solved with a small change in classic Bragg Brentano geometry. The problem is solved by fixing the rotation angle (0) of the sample material. In IXthis way the fixed rotation angle (6) can be taken as small as possible, thus the penetration depth of x-rays becomes smaller and smaller and the best results can be achieved. For instance, in Bragg-Brentano type x-ray thin film diffractometers this angle (6) can be fixed as 0.05°. During the analysis penetration depth of x-ray beams into the sample is constant and very small. x-rays, diffracted from the sample, pass through the thin film collimator before being detected by the detector. The diffracted x-rays become parallel by the collimator. Then x-rays are passed through monochromator, which allows only one type of x-rays to reach to the detector. In classsic powder diffraction, detection of Ka, K" with different energy levels does not create any problem. If the detector counter is higher the seperation is not difficult, as a result the sensitivity of diffraction analysis is not affected by this count. Whereas in thin film analysis detected counts are less than powder analysis. If it is thought as these rays have different energy levels, the analysis can get meaningful after the rays are become parallel by the collimator and the seperation of energy levels are done by the monochromator. The intensity of diffracted x-ray beams are important in powder diffraction and also in thin film analysis. Generally, in x-ray diffraction analysis, the diffracted beam intensity decreases because of the absorbtion of x-rays in sample.The intensity of the diffracted beam is attenuated by the absorbtion of the x-rays in the sample. This attenuation factor is given by 1 Sin61 Sin8, r _ f \ (ii.)p Sine,+Sine2 ' l | where 62 is the angle between the diffracted beam and the sample surface and |i/p is the mass absorbtion coefficient of the sample (u7p is a function of the type of x-ray radiation used). G/ describes the part of the primary x-ray beam which contributes to the intensity of the diffraction peaks of layer which or top layer wyth thickness / on the substrate: G,=1-exp[->/(^+^e;)] By using Bragg Brentano geometry, the thicker the coating thickness is bigger the G/. But the higher the Bragg angles the smaller the G/. However the values of G/ are mostly under 0.5. This means that; primary x- ray beams' profit are about 50% less than the diffracted rays and x-rays, which are generated diffraction patterns and this profit is decreasing with bigger Bragg angles. In Seeman Bohlin geometry where the fixed angle 5°, this addition is around the 40% and it does not change with increasingBragg angle. In fixed angle film geometry this profit is very high. The profit of x-ray beams increase with decreasing angle of x-ray entrance. Such as when 61 is smaller than or equal to 0.6 the addition of primary x-ray diffraction pattern is 100%. The performance of coated layer depends on the interlayer of coating phases and interdiffusion of the phases which occurs between substrate and coating interlayers and diffusion is more important, x-ray diffraction technique is more successfull to investigate this variability between interlayers. In this study the determination of phases and their variations which occur between substrate and transfer zone of coating base are investigated by using x-ray diffraction analysis. It is well known that Ti ions are coated on steel substrate material by cathodic arc methods. In the experimental stage of this study, Armco 0.5C (DIN 45) and 0.9C (DIN 85WS) are used as substrate materials. The goal of this study is to coat these substrates with Ti as a thin film. After coating, coated substrate materials are exposed to different heat treatments to observe different phases that are between substrate materials and coating base. Finally, the different phases which are generated with TiN coatings and different heat treatments investigated by using x-ray diffraction (XRD) technique. In order to achieve good surface quality samples are exposed to mechanical grinding and then polished. Coating layer must be very thin to be able to observe interlayer phases and diffusion. Therefore coating process is done by using Novatech-NVT 12Arc-PVD coating unit. Sample surface is cleaned by Metel 1 0 KW neutral molecule source before the coating. Two different temperature have chosen for the heat treatment stage and these treatments have done under vacuum to prevent the oxidation of Ti. Specimens are exposed to heat treatment in 550° and 650° for 20 minutes. The heat treatment proceses was carried out by using PVD coating machine to supply the needed vacuum and by using electron heating method to provide sufficient temperature. Fallowing results are obtained by investigating the determined x-ray diffraction patterns: 1 ) A comparison of diffraction patterns belonging to classical and thin film methods clearly indicates that the thin film patterns provide more data than its counterparts. XI2) Results of different treatments on three groups of samples are given in Table 1. Table 1.
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