رضایی, حمیدرضا
[ 1 ] - سنتز احتراقی رنگدانه مشکی با اندازه ذرات زیر میکرون بر پایه کرومیت کبالت حاوی منگنز
استفاده از رنگدانه مشکی (با اندازه ذرات میکرونی) از دیرباز در صنعت سرامیک مرسوم بوده است. اخیرا با توسعه صنعت تهیهی جوهرهای سرامیکی به منظور چاپ دیجیتال بر روی کاشی، رنگدانه مشکی با اندازه ذرات زیر میکرون مطرح شده است. با تغییر اندازه ذرات، شید رنگی آنها نیز تغییر خواهد کرد. در این پژوهش سنتز رنگدانه مشکی با اندازه ذرات زیر میکرون بر پایه کرومیت کبالت با افزودن منگنز در درصدهای متفاوت مورد بر...
[ 2 ] - سنتز زئولیت LTAو جذب یون کلسیم از آب توسط آن
نیاز به آب سالم، نیاز همیشگی تمام جوامع بوده و است هرچند که دسترسی به آن همواره میسر نیست. یکی از عواملی که این دسترسی را با مشکل مواجه می‌کند وجود کاتیون‌های سنگین مانند Ca2+ در منابع آب است که خود از مشکلات مهم زیست‌محیطیبه شمار می‌رود. این کاتیون‌های سنگین به روش‌های گوناگونی قابل جداسازی هستند که در این مقاله به بررسی نحوه-ی استفاده از زئولیت‌ها به‌خصوص زئولیت سنتزی LTA جهت نیل به این هدف پ...
[ 3 ] - SYNTHESIS OF AL2O3-NI COMPOSITE POWDERS BY CO-PRECIPITATION METHOD
The synthesis of micro-sized, uniformly distributed Al2O3-15Vol% Ni powders were studied through three step co-precipitation of hydroxides mixtures from proper solution, calcination at air atmosphere and final step of calcined powders in a carbon bed. Al and Ni hydroxide and amorphous phase were first obtained from their salt’s solutions through chemical co-precipitation method by adjusti...
[ 4 ] - THE EFFECT OFCARBON NANOTUBES ON THE SINTERING BEHAVIOR OF ZIRCONIA BASED MATERIALS
Different volume fractions (1.3, 2.6, and 7.6 Vol.%) of carbon nanotubes (CNTs) were dispersed within 8Y-TZP nanopowders. Mixed powder specimens were subsequently processed by spark plasma sintering (SPS) and effects of CNTs on the sintering process of 8Y-TZP/CNT composites was studied. Maintenance of CNTs through the SPS process was confirmed using TEM and Raman Spectroscopy. Studies on the si...
[ 5 ] - تعیین دمای بهینه عملیات حرارتی جهت دستیابی به پوشش نانوساختار هیدروکسی آپاتیت
چکیده پوشش هیدروکسی آپاتیت (HA) با اندازه ذرات نانومتری از طریق افزایش القا و هدایت استخوانسازی در اطراف کاشتنیهای استخوانی، زمان تثبیت آنها را در بافت میزبان کاهش میدهد. در این پژوهش با استفاده از روش سل - ژل اقدام به ایجاد پوشش HA بر سطح آلیاژ Ti-6Al-4V گردید. با انجام آزمونهای FTIR، XRD و STA برروی پودر حاصل، سیکل عملیات حرارتی مناسب جهت دستیابی به پوشش HA نانوبلوری با خلوص و پایداری با...
[ 6 ] - Determination of cristobalite phase content in ceramic cores using various X-ray quantitative phase analysis methods
The aim of this research is to investigate different X-ray based quantitative phase analysis methods for determination of cristobalite phase content in ceramic cores. For this purpose, four popular routes including peak absolute intensity method, relative intensity ratio method, direct or calibration method and internal standard (or Alexander-Klug) method have been chosen. Some control samples ...
[ 7 ] - Spark Plasma Sintering of Ultra-High Temperature Tantalum/Hafnium Carbides Composite
TaC and HfC are thought to have the highest melting point (~4000°C) among all refractory materials. The binary solid solution of TaC and HfC (Ta4HfC5) is also considered as the most refractory material with the melting point over 4000 °C and valuable physical and mechanical properties. The main goal of this work is to fabricate TaC/HfCbased composites which consolidated by means of spark plasma...
[ 8 ] - Effects of N-Vinylcaprolactam Containing Polyacids and Zirconia on Mechanical Properties of Commercial Glass Ionomer Cements
This study aimed to investigate the impact of N-vinylcaprolactam (NVC) and Nano-sized yttria-stabilized zirconia (YSZ), separately and simultaneously, on the mechanical properties of the commercial glass ionomer cements (GICs). Methods: The NVC is able to ameliorate the mechanical and surface properties of glass ionomers; however, its effect hasn’t been investigated in conjunc...
[ 9 ] - Fabrication and Characterization of Polycaprolactone – Zeolite Y Nanocomposite for Bone Tissue Engineering
In recent years, nanoceramics have been used in scaffolds to emulate the nanocomposite with a three-dimensional structure of natural bone tissue. In this regard, polycaprolactone biopolymer is widely used as a scaffold in bone tissue engineering. The goal of this research is to produce porous scaffolds of polycaprolactone - zeolite biocomposite with suitable mechanical, bioactive and biological...
[ 10 ] - The effect of Ag and Co dopants on structural and antibacterial properties in hydroxyapatite
This research was conducted to develop antibacterial properties in HA composite by doping Ag-Co simultaneously. Chemical compounds Ca10-x Ag x/Co y(PO4)6 (OH)2 with values (x, y= 0, 0.5, 1) were synthesized by co-precipitation method which is an economical and simple way. XRD, FESEM and EDS analysis were used to investigate structural and microstructural characteristics. The result of XRD ana...
[ 11 ] - Effect of citric acid chelating agent on morphology of ZnO particles prepared by hydrothermal method
Abstract Zinc oxide is one of the most widely used and important materials in today's science and industry. In this study, ZnO nanoparticles were synthesized by hydrothermal method. Zinc acetate, citric acid and deionized water was respectively used as a source of zinc ion, solvent and chelating agent. In this study, the effect of citric acid concentration as an additive was studied on morphol...
[ 12 ] - Investigation of the synergistic effect of titania micro and nanoparticles on the hydrophobic properties of polyurethane composite coating
One of the ways to improve the performance of ceramic insulators in polluted climates is to use polymer coatings reinforced with ceramic particles. The purpose of this study is to compare the effect of adding Titania nanoparticles and Titania micro-nanoparticles on hydrophobic properties of PU. In this method, stearic acid, which is a cheap and environmentally friendly material, was used for su...
[ 13 ] - Investigation of process factors in the synthesis of Ca7ZrAl6O18 cement by solid state method in order to eliminate undesirable secondary phases
One of the widely used cements for filling teeth and bones can be calcium zirconium aluminate cement Ca7ZrAl6O18, which of course can also be used as a refractory. The behavior and properties of this cement are more similar to tricalcium aluminate C3A cement. In this study, C7A3Z cement was synthesized by using commercial calcium carbonate, alumina and zirconia powders and after grinding for 4-...
[ 14 ] - Synthesis and application of mesoporous gamma alumina granules as iridium catalyst support
Mesoporous gamma-alumina granules, which are known as a common catalyst support in industrial applications were synthesized via the sol gel-oil drop method having a diameter of 1-2 mm. The effect of calcination temperature (450 and 750 °C) on the properties of gamma alumina granules were studied and the functionality of 20 wt% iridium catalyst on the alumina granules for hydrazine decomposition...
نویسندگان همکار