A New Approach — In-Situ Codeposition of Composite Coatings

Present chapter is organised to give general information about electrolytic coating and electro codeposition, factors affect the coating structure and the main layers’-property relation in details. This relation is expressed by a simple schematic and electrolytic codeposition parameters affect the process such as pH, zeta potential, agitation and etc. are explained. Additionally, in-situ codeposition, the new approach is given with examples, and some experimental results belonging to our research group and with comparison to approaches belonging to some others

Electrolytic co-deposition of carbon nanoparticles with metals, improvement of corrosive and mechanical properties

Bu çalışmanın ana fikri elektrolitik birlikte kaplama sistemi ile krom-karbon siyahı kompozit kaplamaların üretilmesi ve ilave ısıl işlemler ile metal-seramik kompozit yapıların elde edilmesidir. Burada ilave ısıl işlemler, yerinde faz dönüşümlerinin gerçekleştirilmesi için amaçlanmıştır. Sözü edilen kompozit yapılar, nano/mikron altı boyutta karbon siyahı partiküller içeren sülfürik asit bazlı çözeltilerde kaplanmıştır. Krom matriks kompozit kaplamalarda karbür faz dönüşümü üzerine ısıl işlemin etkisi ile bunların korozyon ve mekanik davranışları araştırılmıştır. Elde edilen sonuçlar göstermiştir ki; krom-karbon kompozit kaplamalar bu teknikle başarılı bir şekilde üretilebilmektedir ve ilave ısıl işlemlerle krom-krom karbür ve/veya krom nitrür kompozit yapıların çelik altlıklar üzerinde oluşturulması mümkündür. Kaplamalar, geleneksel sert krom kaplamalarla karşılaştırılmıştır. Elektrokimyasal davranışları göz önünde bulundurulduğunda; bir anlamda onarılmış, çatlaksız mikro yapıya sahip olan, azot atmosferinde 800oC?de ısıl işlem görmüş krom-karbon siyahı kompozit kaplamaların geleneksel sert krom yapılara nazaran daha iyi bir korozif direnç gösterdikleri belirlenmiştir. Burada; korozyon direncinin artmasına karşılık gelen korozyon potansiyelindeki yükseliş, krom karbür/krom nitrür oluşumu ile açıklanmıştır. Karbür ve nitrür fazlar oluşturulan kompozit kaplamalarda sertlik ve elastisite modülü gibi karakteristik özellikler belirlenmiş, sözü edilen faz dönüşümlerinin malzemeye ait sürtünme-aşınma karakteristiğinde ve altlık-kaplama ara yüzey uyumunda önemli derecede iyileşmeyi tetiklediği gözlemlenmiştir. Detaylı incelemelerle, bu nihai sonuçların temelde yapıdaki kalıntı gerilmelerin büyüklüğü ve yönü ile doğrudan ilişkili olduğu tespit edilmiştir. Elde edilen tüm mükemmel sonuçlar, krom matriks-karbür ve/veya nitrür takviyeli kompozit kaplamaların endüstriyel alanda birçok açıdan potansiyel uygulamalar bulacağının göstergesidir. Main idea of this study is to fabricate chromium-carbon black composite coatings by electro-codeposition system and to obtain metal-ceramic composite structures with additional heat-treatments. These heat-treatments were aimed to realize in-situ phase transformations. The composite structures referred were electro-codeposited in sulfuric acid based solutions containing nano/submicron sized carbon black particles. The effect of heat-treatment conditions on the in-situ carbide phase formation in the chromium matrix composite coatings, and their corrosion and mechanical behaviors were investigated. The obtained results showed that the chromium-carbon composite coatings can be fabricated successfully by this technique and with an additional heat-treatment; it is possible to obtain a chromium-chromium carbide and/or chromium nitride composite structure on steel substrates. The coatings were compared with respect to the conventional hard chromium coatings. In regard to the electrochemical behavior, the chromium-carbon black composite coatings heat-treated under nitrogen atmosphere at 800oC showing a rehabilitated crack-free microstructure, exhibited better corrosion resistance than the conventional hard chromium structures. Therefore, the increase in corrosion potential suggests improvement of corrosion resistance due to the formation of chromium carbide/chromium nitride. Characteristic properties such as hardness and modulus of elasticity were determined for carbide and nitride formed composite coatings. It was observed that the following phase transformations support the recovery of friction-wear characteristics and accordance of substrate-coating interface belonging to the material. According to the detailed inspections, it was assigned that the definite results are directly correlate with both the magnitude and the direction of the residual stresses. All the excellent results obtained implies that the chromium matrix-carbide and/or nitride reinforced composite coatings have potential application to industrial fields in many respects

Metal filmlerin seramik nanopartiküllerle birlikte elektrokimyasal yöntemle metalik altlıklar üzerine depozitlenmesi

Bu çalışmada; çinko (Zn) ve krom (Cr) metalleri ile mikron-altı boyutta alümina (Al2O3), silisyum karbür (SiC) ve tungsten karbür (WC) seramik partikülleri, elektrokimyasal yöntemle birlikte depozitlenerek Zn-Al2O3, Cr-SiC ve Cr-WC metal matrisli kompozit yapıları oluşturulmuştur. Burada; geleneksel elektrokimyasal hücre yerine, yeni sistemler tasarlanmıştır ve kaplamalar çeşitli elektrolit kompozisyonları için bu sistemlerde üretilmiştir. Sözü edilen kompozit kaplamalar; akım yoğunluğu, pH, sıcaklık, karıştırma tipi, akım tipi ve frekans gibi birlikte depozitlemeyi etkileyen sistem parametrelerinin çeşitli kombinasyonları için üretilmiştir. Üretilen kompozit yapıların faz ve morfolojik yapıları, elementsel haritalama sonuçları gibi nitel ve nicel karakterizayson işlemleri, Shimadzu-6000 model XRD (X-ışınları difraktometresi) SEI ve BEI olmak üzere iki farklı modda görüntü alabilen, EDS (enerji saçınım spektrometresi) entegreli JEOL-JJM 6060 model SEM (taramalı elektron mikroskobu) cihazlarında incelenmiştir. Bunun yanında kompozit yapılara ait sertlik, elastisite modülü ve % elastik toparlanma gibi mekanik özellikler 0,1 - 1961 mN yük aralığında çalışabilen Shimadzu DUH-W201, DUH-W201S model Dinamik Mikro-Sertlik Test cihazında, 25 mN yük altında ve 98,07 mN (HV0,1) - 19.614 N (HV2) çalışma aralığı kapasiteli Shimadzu HMV-2 model Mikro-Sertlik Test cihazında 980, 7 mN yük altında belirlenmiştir. Sonuç olarak bu çalışma, Al2O3/SiC/ WC gibi seramik partiküllerin katot yüzeyinde fiziksel olarak absorblanarak Zn/Cr gibi metallerle kompozit yapılar oluşturduğunu ve metallerle mikron-altı boyuttaki seramik partiküllerin elektrodepozitleme sistemi ile başarılı bir şekilde birlikte depozitlendiğini göstermiştir. In this research; submicron sized ceramic particles alumina (Al2O3), silicon carbide (SiC) and tungsten carbide (WC) were co-deposited with metals zinc (Zn) and chromium (Cr) via electrodeposition system to fabricate Zn-Al2O3, Cr-SiC and Cr-WC metal matrix composite structures. With this aim, new systems were designed instead of traditional electrodeposition cells and coatings were fabricated in these systems for different electrolyte compositions. These composite coatings were produced under different combinations of system parameters such as current density, pH, temperature, current type and frequency which effect co-deposition directly. Phase identifications of the fabricated composite coatings were performed by Shimadzu-6000 model XRD (X-ray diffractometer) and surface morphologies were investigated using JEOL-JJM 6060 model SEM (scanning electron microscopy) with an EDS (energy dispersive X-ray spectroscopy) system attachment. Nevertheless, mechanical properties of the coatings such as hardness, elestic modulus and % elastic recovery rate were performed under 25 mN applied load by Shimadzu DUH-W201, DUH-W201S model Dynamic Micro-Hardness Tester with a working range 0,1 ”“ 1961 mN and under 980, 7 mN applied load using Shimadzu HMV-2 model Micro-Hardness Tester with a working range 98,07 mN (HV0,1) - 19.614 N (HV2). It was concluded that ceramic particles Al2O3/SiC/WC were physically absorbed to the cathode surface and made a composite structure with metal Zn/Cr and co-deposition of sub-micron sized ceramic particles with metals via electrodeposition system was strictly successful

Super hard WC-Cr composite coatings: An approach to potential wear applications

In this study, submicron (APS = 200 nm) tungsten carbide (WC) ceramic particles were co-deposited with chromium metal (Cr) via electro-co-deposition system to fabricate WC-Cr metal matrix composite coatings. Instead of traditional electrodeposition cells, a new system was designed and coatings were fabricated using this system. Phase identifications of the coatings were performed by X-ray diffractometry (XRD) and surface morphologies were investigated using energy dispersive X-ray spectroscopy (EDS) with attached scanning electron microscope (SEM). Hardness values of the coatings were performed under 980.7 mN applied load using a microhardness tester. It was concluded that WC ceramic particles were physically adsorbed on the cathode surface and formed a composite structure with metal Cr and co-deposition of submicron sized ceramic particles with metals via electrodeposition system was strictly successful. In addition, with respect to the reference coatings, WC reinforced composite coatings depict an increased hardness up to twice its value. Frequency, as a parameter of pulse current, is determined as an effective parameter in co-deposition

Fabrication of Cr-Cr23C6/Cr2N Composite Coatings: Change in the Phase Structure and Effect on the Corrosion Properties

Cr-C composite coatings were electro-codeposited in sulfuric acid-based solutions containing submicrometer-sized carbon black particles. The effect of heat-treatment conditions on the carbide phase formation in the composite coatings and their corrosion behaviors were investigated. The obtained results showed that the Cr-C composite coatings can be fabricated successfully and with an additional heat treatment, it is possible to obtain a Cr-Cr23C6/Cr2N composite structure. Therefore, the increase in corrosion potential suggests improvement in corrosion resistance due to the formation of Cr23C6/Cr2N. This implies that Cr-Cr23C6 and/or Cr2N composite coatings have potential application to industrial fields in many respects

Degradation of contaminated ındustrial waste water using sol-gel derived ru-doped tio2 photocatalytic films

In this study, Ru-TiO2 films were deposited on glass substrates with a sol-gel route for degradation of contaminated industrial water. A solution with the Ru/Ti molar ratio of 0.05 was prepared using ruthenium and titanium based precursors. Solution characterizations were made using a turbidimeter and pH meter. the gel films, prepared by the sol-gel drop casting method, were dried at 300°C for 10 minutes and subsequently heat-treated at 500°C for 5 minutes in air. After that, the oxide thin films were annealed at 600°C for 60 minutes in air. in order to evaluate the phase structure, microstructure, optical, and photoca- talytic properties of the coatings, they were investigated using XRD, SEM, and UV/Vis spectrophotometer, respectively. the obtained phase was mostly anatase TiO2. Photo-oxidation experiments were performed to obtain the photocatalytic activity of the films on impure water using an UV light source. the absorption spectrum of the water samples taken from Cigli Industrial Plant and Gediz River in Izmir/Turkey showed that they have absorbance bands in the range of 300 nm and 500 nm. the Ru doped TiO2 films exhibited highly photocatalytic activity to decompose organic species in contaminated waters. the degradation percentage ratios were calculated as 75% and 62% for two different industrial water samples.Bu çalışmada, sol-jel yöntemiyle cam altlıklar üzerine hazırlanmış Ru katkılı TiO2 filmler endüstriyel kirli suların temizlenmesi için kullanılmıştır. 0,05 Ru/Ti molar oranı içeren çözelti rutenyum ve titanyum esaslı prekürsörler kullanılarak hazırlanmıştır. Hazırlanan bu çözeltinin karakterizasyonu, türbidimetre ve pH metre kullanılarak gerçekleştirilmiştir. Sol-jel damlatma metodu ile hazırlanan jel filmler hava ortamında 300°C’de, 10 dakika süre ile kurutulmuş ve hemen ardından 500°C’de 5 dakika süreyle ısıl işleme tabi tutulmuştur. Son olarak bu oksit filmler yine hava ortamında 600°C’de ve 60 dakikada tavlamaya maruz bırakılarak film oluşturma işlemi tamamlanmıştır. Bu kaplamaların faz yapısını, mikroyapısını, optik ve fotokatalitik özelliklerini incelemek için sırasıyla XRD, SEM ve UV/Vis spektrofotometre teknikleri kullanılmıştır. Elde edilen faz, büyük oranda anataz TiO2 yapısındadır. Foto-oksidasyon deneyleri, üretilen oksit filmlerin UV ışık kaynağı kullanılarak kirli su içinde fotokatalitik aktivitelerinin belirlenmesi için gerçekleştirilmiştir. Çiğli Sanayi Bölgesi’nden ve Gediz Nehri’nden alınan kirli su örneklerinin absorbans spektrumları özellikle 300 nm ile 500 nm dalgaboyları arasında yüksek absorbans bandı sergilemişlerdir. Sentezlenen Ru katkılı TiO2 filmlerin endüstriden alınan su örneklerindeki organik kirliliklerin parçalanmasında çok yüksek fotokatalitik aktiviteye sahip oldukları gösterilmiştir. İki farklı su örneği için parçalanma yüzde oranları %75 ve %62 olarak hesaplanmıştır

A Comparison on Physical, Structural, and Photocatalytical Properties of TiO2 Nanopowders Produced Using Sol-Gel and Flame Spray Pyrolysis

In this study, nanoscale photocatalyst TiO2 powders were synthesized via sol-gel and flame spray pyrolysis (FSP). Phase structures and ratios were analyzed by X-ray diffractometer (XRD). Size, specific surface area, and morphologies were determined using particle size analyzer, Brunauer-Emmett-Teller theory, and scanning electron microscope, respectively. Anatase phase with some rutile together was obtained in XRD analysis. The degradation rates of aqueous methylene blue (MB) by TiO2 nanopowders were calculated using UV-vis spectrophotometer. It was found that MB decomposition was successfully achieved with significantly high efficiencies for both sol-gel and FSP-derived powders with small differences

ELECTRO-CODEPOSITED Cr-SiC COMPOSITE COATINGS: EFFECT OF THE PULSE-CURRENT FREQUENCY ON MORPHOLOGY AND HARDNESS

In this research, submicrometer silicon-carbide (SiC) (APS = 200 nm) ceramic particles were co-deposited with chromium metal (Cr) via an electrodeposition system to fabricate Cr-SiC metal-matrix composite films Phase identifications of the fabricated composite coatings were performed with an X-ray diffractometer (XRD) and surface morphologies were investigated using a scanning electron microscope (SEM) with an energy dispersive X-ray spectroscopy (EDS) system attachment. Mechanical properties of the coatings such as hardness were determined under an applied load of 980.7 mN using a micro-hardness tester. It was concluded that SiC ceramic particles were physically adsorbed on the cathode surface forming a composite film structure with Cr metal and that a co-deposition of the sub-micron-sized ceramic particles with metals via an electrodeposition system was successful. In addition, in comparison with the reference coatings, the hardness of the SiC-reinforced composite coatings was increased by up to 50 %. The frequency, being a parameter of pulse current, is determined as an effective parameter in a co-deposition of ceramic particles with metals