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Article
Fabrication, Characterization and Modeling of Al2o3/Ni Functionally Graded Materials
تصنيع , دراسة خواص ونمذجة مواد متدرجة بالخواص ذات اساس نيكل – الومينا

Author: Alaa Abdulhasan Atiyah
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 9 Part (A) Engineering Pages: 2286-2302
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Functionally graded materials (FGMs), with ceramic and metallic constituents, are frequently used for tremendous high temperature applications. In this paper, six sets of FGMs samples were designed and fabricated using powder technology technique. All FGMs were sorted according to the conditions of sintering (i.e. temperature and time). The ceramic constituents were represented by (Al2O3) and the metallic constituents were represented by (Ni).It is found that as the sintering temperature and time increased, the apparent density was increased and porosity was reduced. (F-FGM, sintered at 1350°C for 3 hrs.) sample seems to impart high and slight linear graded microhardness across the layers without any obvious jumps throughout the thickness. The interfacial microhardness values were found very close to the bulk microhardness of adjacent layers. The reason behind such behavior is the minimum porosities and improved apparent density due to the efficient sintering practices (i.e. 1350°C and 3 hrs.) and uniform mutual diffusion of (Ni) and (Al2O3) particles across the layer interfaces. As the sintering time and temperature increase, the microstructure becomes much denser and the interfaces become more homogeneous that lead to eliminate the discontinuity in microstructure. A Finite element method throughout the COMSOL Multiphysicswas used extensively in estimation of temperature distribution through the thickness as well as residual stresses that induced as a result of high temperature loading of fabricated FGM. The model also shows aclear fluctuation of stresses along the thickness that imparts a development of stress concentration regions near the interfaces of layers, especially at the lower half region of FGM that was enriched by (Ni). Stresses clearly become normal variables with thickness at the upper half of FGM that enriched with (Al2O3).

المواد المتدرجه وظيفيا ( FGMs ) التي تتكون من المواد السيراميكيه والمعدنية التي كثيرا ما تستخدم في تطبيقات درجة الحرارة العاليه. في هذه البحث ، تم تصميم و تحضير ست مجموعات من عينات المواد المتدرجه بالخواص (FGMs) باستخدام تكنولوجيا المساحيق.إن مكونات الماده السيراميكيه ممثله بالألومينا (Al2O3) والمكونات المعدنيه متمثله بالنيكل .(Ni) لقد ثبت أن زيادة درجة حرارة وزمن التلبيد يعملان على زيادة الكثافه الظاهريه وتقليل نسبة المساميه.لقد اثبتت النتائج العمليه ان العينه F-FGM )التي تم تلبيدها بدرجة حرارة 1350 درجه مئويه وزمن 3 ساعات( قد اظهرت تدرجا خطيا واضحا وارتفاعا مرضيا في قراءات الصلادة الدقيقة بمقياس فيكرز عبر طبقات الماده. كما تم العثور على قيم الصلادة الدقيقة البينية (الحد الفاصل بين الطبقات) قريبة جدا من قيم الصلاده الدقيقه للطبقات المجاورة. ان الأسباب الكامنة وراء مثل هذا السلوك هي وجود الحد الادنى من نسبة المسامية والتحسن الجيد في قيم الكثافه الظاهريه في هذه العينه التي جاءت بسبب كفاءة التلبيد المعتمده في هذا البحث (C°1350 وزمن تلبيد 3 ساعه). كما تجدر الاشاره الى ان البنيه المجهريه تصبح اكثر كثافه والحدود الفاصله بين الطبقات تصبح اكثر تجانسيه مع زيادة درجة حرارة وزمن التلبيد. لقد تم ايضا استخدام طريقة العناصر المحدده وذلك من خلال برنامج الكومسول (COMSOL)الذي استخدمت نتائجه للتثبت من تدرج الخواص ودرجات الحراره بفعل التوصيل الحراري. كما تشير نتائج نمذجة الاجهادات الى وجود تذبذب في نتائج الاجهادات على طول سمك العينه (F) وخاصة في المناطق القريبه من الحدود الفاصله بين الطبقات وبالخصوص في الجزء الاسفل من الماده والغني بعنصر النيكل. بينما تبدو النتائج اكثر سلاسه وخطيه في الجزء العلوي الغني بمادة الالومينا.


Article
Design and Modelling of (Fe /Zro2) Functionally Graded Materials (Part I)
تصميم ونمذجة مادة متدرجة بالخواص ذات اساس (حديد /زركوينا) (الجزء الاول)

Authors: Alaa Abdulhasan Atiyah --- Ahmed Taifor Aziz
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 7 Part (A) Engineering Pages: 1843-1858
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

It is hoped to design and modeling of five layers Fe/ZrO2 functionally graded materials for high temperature applications in this paper. The design part, were started with the supposing of connecting two distinct material layers. The two layers were associated by a graded interface composing of three layers. Thickness of graded layer (i.e. RF) was designed and tested with the FEM method through the COMSOL package. The software was used extensively to examine the best graded part thickness percentage (i.e.RF %) that connecting the two different material layers. Two parameters were examined such as N and RF% to determine the best value of (N) and (RF %) that imparts low residual stresses. Thermal stresses that developed as a result of exposing of material to high temperature environments also calculated. The simulation indicates that the sample with (RF= 80% and N = 0. 7) Provides minimum residual stress at high working temperature 1000℃ with good mechanical properties.

نأمل في هذا البحث التوصل الى نمذجة ماده متدرجه بالخواص ذات اساس (حديد / زركونيا) مكونه من خمس طبقات جرى تصميمها للعمل في في تطبيقات درجات الحراره العاليه. ان هذا الجزء من البحث بدأ بأفتراض ان من الممكن ربط طبقتين مكونتين من مادتين مختلفتين. وهاتان الطبقتان يتم ربطهما من خلال ثلاثة طبقات متدرجه. إن سمك هذه الطبقات الثلاثه (RF ) قد تم تصميمه واختياره بأستخدام طريقة العناصر المحدده من خلال برنامج (COMSOL ). ولقد تم استخدام هذا البرنامج بعمق لأختبار افضل نسبة سمك للطبقات الوسطيه المتدرجه (RF% ) التي تربط كما اشرنا طبقة الحديد من الاسفل مع طبقة الزركونيا من الاعلى. تم دراسة تأثير عاملين مهمين وهما المعامل (n) وكذلك (RF% ) اللتان تعطيان اقل اجهادات متبقيه بين الطبقات. تم إحتساب الاجهادات الحراريه التي تنتج عن تعرض الماده الى درجات حراريه عاليه. ان النمذجه ببرنامج COMSOLاثبتت ان نسبة RF% = 80% و N = 0.7 ) سوف تعطيان اجهادات متبقيه منخفضه عندما تعمل الماده في درجات حراره عاليه (1000 مئوي) وخواص ميكانيكيه عاليه.


Article
High Performance Concrete Improvement by Styrene-Butadiene Rubber Addition

Authors: Alaa Abdulhasan Atiyah --- Saad B. H. Farid --- Ahmed Saad Kadhim
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 12 Part (A) Engineering Pages: 2296-2309
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In this paper, the properties of high performance concretes modified by polymer were studied. Liquid synthetic styrene-butadiene rubber (SBR) was added (5%, 10% and 15%) by weight of cement to high performance concrete (HPC) to elucidate the effect of the polymer additive to their properties.The compressive strength, splitting tensile strength, flexural strength, porosity, dry density and total water absorption were measured.Thermal conductivity, thermal diffusivity and specific heat of HPC isalso measured. In addition, SEM micrographs are compared reference and polymer modified HPC.The results show that there is an improvement in the workability for HPC after the addition of the polymer. Furthermore, the density of the set concrete was increased and both the porosity, total water absorption was decreased. Thermal conductivity, thermal diffusivity, and specific heat show improvement after polymer addition, which indicate better endurance.The SBR modified HPC, exhibits a significant improvement in splitting tensile strength and flexural strength, although it was at the expense of the compressive strength to some extent.The HPC has shown balanced microstructure before and after the addition of polymer, although they noticed improved on the ductile properties.


Article
Design and Preparation of Stepwise Functionally Graded Materials Used for Internal Combustion Engine Piston Applications

Authors: Alaa Abdulhasan Atiyah --- Mohammed H.Hafidh --- Ahmed H.Ali
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 13 Part (A) Engineering Pages: 2387-2397
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This work includes the design and preparation of a(Low carbon steel / AL2O3) stepwise functionally graded crown part of an internal combustion engine piston. Powder technology technique, has been studied to improve engine thermal efficiency by creating semi adiabatic combustion chambers, where ceramic phase facing the hot combustion gases, while metallic phase assembling with other parts of the piston. Finite element method ABAQUS program had been used to minimize nucleated residual stresses generated under fabrication process and service work conditions by designing the compositional graded of stepwise FGM within specific dimensions, in addition to temperature distribution across FGM thickness. Then the fabricated specimens had SEM imaging, physical and mechanical property inspection. The results also show that linear transition from metal to ceramic structure can provide minimum residual stresses under all conditions, using stepwise FGM can improve engine heat efficiency by doubling the crown surface temperature,(622) ºC, comparing with steel crown, (322) ºC, under the same applied heat flux. Physical inspections show limited relative density, (48.5) %, with high total porosity structure, (53.3) %, can be performed by this fabrication method. Mechanical tests results show that the layers’ hardness increase with increasing ceramic content, and decrease with increasing pores percentage. Compression test shows the ability of suggested stepwise FGM to withstand service work stresses of combustion chamber without failure.

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Article
PREPARATION & CHARACTERIZATION OF STEP-WISE AL-AL2O3 FUNCTIONALLY GRADED MATERIALS

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Abstract

In this work, simple ceramic-metal functionally graded materials with three different layers has been prepared and tested. Ceramic and metal materials were represented by alumina and aluminum respectively. Powder technology practices were used extensively in preparing each of four set of FGMs samples. All samples have the same chemical composition. Two variables were studied, compacting load and sintering temperature. All samples were imparting graded hardness reading across the thickness. The values of hardness readings are increased according to the hardest constituent’s increment (i.e. Alumina) at constant sintering temperature and compacting load. Compaction load increment as well as sintering temperature imparts another reasons for improvement in hardness properties. Microscopic observations show an interesting features of the layers microstructure where composed from an aluminum and alumina particles and show good adhesive between alumina particles and Aluminum while Aluminum surrounded alumina particles from all studies due to good mixing practice during preparation stage.

تم في هذا العمل تحضير واختبار مواد المتدرجه بالخواص مكونه من ثلاث طبقات من سيراميك – معدن. السيراميك والمعدن متمثل بالالومينا والالمنيوم على التوالي. طريقه تكنولوجيا المساحيق استخدمت خصيصاً في تحضير اربع مجاميع من عينات المواد المتدرجه بالخواص، كل العينات تمتلك نفس التركيب الكيمياوي. وتم دراسه متغيرين ، حمل الكبس و درجه حراره التلبيد. ازدادت قراءات قيم الصلاده وفقا لزياده المكون الاصلد (الالومينا) عند ثبوت درجه حراره تلبيد و حمل الكبس. تلعب زياده حمل الكبس ودرجه حراره التلبيد كسبب اخر في تحسين خواص الصلاده. اظهرت الملاحظات التركيبيه خواص مميزه للطبقات والمتكونه من الالمنيوم ودقائق الالومينا واظهرت التصاقا جيدا بين دقائق الالومينا ومعدن الالمنيوم بينما احاط الالمنيوم دقائق الالومينا في جميع الحالات نتيجة للخلط الجيد اثناء عملية التحضير.

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