نتایج جستجو برای: surface micro cracks

تعداد نتایج: 748100  

رضوانی, محمد باقر, محمدی بصیر, مهشید, مرادی, زهره, چینی‌فروش, نسیم,

Objective: The aim of this study was to evaluate and compare the effect of dental surface treatment with Er:YAG , Nd:YAG ,CO2 lasers and sodium ascorbate to recently laser bleached enamel by scanning electron microscope (SEM). Methods: 15caries-free extracted human third molars were selected for this study. The samples were bleached by Heydent JW power activated by diode laser 810 nm. After 7 d...

پایان نامه :وزارت علوم، تحقیقات و فناوری - پژوهشگاه مواد و انرژی - پژوهشکده سرامیک 1392

thermal barrier coatings (tbcs) are used to provide thermal insulation to the hot section components of gas turbines in order to enhance the operating temperature and turbine efficiency. hot corrosion and thermal shocks are the main destructive factors in tbcs which comes as a result of oxygen and molten salt diffusion into the coating. in this thesis atmospheric plasma spraying was used to dep...

2016
Heesup Choi Masumi Inoue Sukmin Kwon Hyeonggil Choi Myungkwan Lim

Although concrete is one of the most widely used construction materials, it is characterized by substantially low tensile strength in comparison to its compression strength, and the occurrence of cracks is unavoidable. In addition, cracks progress due to environmental conditions including damage by freezing, neutralization, and salt, etc. Moreover, detrimental damage can occur in concrete struc...

Journal: :Optics express 2008
Z B Wang Wei Guo A Pena D J Whitehead B S Luk'yanchuk Lin Li Z Liu Y Zhou M H Hong

Based on medium-tuned optical field enhancement effect around a self-assembled particle-lens array (PLA) irradiated with a femtosecond (fs) laser source, we demonstrated that high-precision periodical array of micro/nano-structures can be readily fabricated on glass surface or inside glass in large areas in parallel without any cracks or debris. The technique has potential for rapid fabrication...

In this work, the mechanism for fracture of brittle substances such as rocks under a uniform normal tension is considered. The oriented straight micro-cracks are mostly created in all the polycrystalline materials resulting from the stress concentrations. The present work focuses on the interactions of the pre-existing micro-cracks, which can grow and propagate within a rock-like specimen. The ...

Journal: :Journal of biomedical research & environmental sciences 2022

The primary purpose of the review is to describe biological growth and its effects on goepolymeric ordinary concrete surfaces. As ages, surface alkalinity wears off by carbonation weathering,thus prepares a suitable environment for growth. Micro-organisms such as algae, fungi various types bacteria start accumulate subsequently penetrate into micro-cracks structures, resulting in bursting stres...

2017
Azadeh Harandi Sina Mirzaeerad Mahgol Mehrabani Elham Mahmoudi Ali Bijani

Introduction This study aimed to compare the incidence of dentinal crack formation by instrumentation with ProTaper Universal system (rotary, multi-file system), SafeSider (reciprocation movement, multi-file system) and Neolix (rotary, single-file system). Methods and Materials In this in vitro study, 60 freshly extracted mandibular first molars were randomly divided into three experimental g...

2014
Amit Rai Y. P Joshi

In conventional concrete, micro-cracks develop before structure is loaded because of drying shrinkage and other causes of volume change. When the structure is loaded, the micro cracks open up and propagate because of development of such micro-cracks, results in inelastic deformation in concrete. Fibre reinforced concrete (FRC) is cementing concrete reinforced mixture with more or less randomly ...

Journal: :international journal of advanced design and manufacturing technology 0
masoud farahnakian faculty of engineering, mechanical engineering department najafabad branch, islamic azad university, iran h. ُُshahrajabian faculty of engineering, mechanical engineering department najafabad branch, islamic azad university, iran

lapping is one of the most important polishing processes which can be used to fabricate flat and smooth surfaces. in this paper, the effect of lapping characteristics and mesh number of abrasive particles are studied on the surface roughness and flatness for the machining of hardened aisi 52100 rings. the most significant lapping characteristics are pressure, lap plate speed and time. scanning ...

Journal: :Procedia structural integrity 2022

Laser processing of cutting tool materials particularly cemented carbides can induce many surface defects including porosity, balling, and micro-cracks. When present in the microstructure tools, micro-cracks lead to chipping early failure. The detection identification cracks be used predict performance post laser processing. To develop a method for crack scanning electron microscopy (SEM) image...

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