نتایج جستجو برای: hfb2

تعداد نتایج: 67  

Journal: :Journal of Physical Chemistry C 2021

Metal diborides are a class of ceramic materials with crystal structures consisting hexagonal sheets boron atoms alternating planes metal held together mixed character ionic/covalent bonds. Many the ultrahigh-temperature ceramics such as HfB2, TaB2, and ZrB2, which have melting points above 3000 °C, high mechanical hardness strength at temperatures, chemical resistance, while MgB2 is supercondu...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تبریز - دانشکده مهندسی مکانیک 1394

توسعه سرامیکهای دما بالا (uhtc) در دهه اخیر گسترش فراوان یافته و این امر نیز خود سبب توسعه تجهیزات هوا فضا شده است. یکی از مهمترین اجزاء این سرامیکها عناصر گروه iv و فلزات انتقالی نظیر zrb2 و hfb2 هستند، که به علت نقطه ذوب بالا نزدیک به 3200 درجه سانتیگراد و علاوه بر این مدول الاسیسته بالا، هدایت حرارتی بالا و .. را نیز فراهم می سازند، هرچند مقاومت به اکسیداسیون در دمای بالا این ترکیبات چندان م...

2017
Jing An Jinpeng Song Guoxing Liang Jiaojiao Gao Juncai Xie Lei Cao Shiying Wang Ming Lv

The effects of HfB₂ and HfN additions on the microstructures and mechanical properties of TiB₂-based ceramic tool materials were investigated. The results showed that the HfB₂ additive not only can inhibit the TiB₂ grain growth but can also change the morphology of some TiB₂ grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine micro...

Journal: :Ceramics International 2022

We report high-quality, hard (31–41 GPa), crack-resistant (hardness-to-effective Young's modulus ratio of 0.13–0.16) and electrically conductive (2.8–4.2 × 105 S m?1) HfB2-based ceramic materials with high thermal stability. The were prepared in the form well adhesive films using a simple deposition process: pulsed magnetron sputtering (B4C target overlapped by metal stripes) onto floating subs...

1999
Rajan Tandon Gregory E. Hilmas Jochen Marschall

The high-velocity impact resistance of hot-pressed zirconum diboride with 30 volume percent silicon carbide was studied using a combined experimental and computational approach. Test specimens in the form of 2 mm thick polished disks were impacted with -0.8 mm diameter tungsten carbide spheres at velocities up to 320 d s . The intrinsic flexure strength of the specimens was -1000 MPa. The flexu...

2017
V. Niderkorn D. P. Morgavi Bettina Aboab Marielle Lemaire H. Boudra

Aims: The ability of lactic acid bacteria (LAB) to bind fumonisins B1 and B2 (FB1, FB2) in fermented foods and feeds and in the gastrointestinal tract could contribute to decrease their bioavailability and toxic effects on farm animals and humans. The aim of this work was to identify the bacterial cell wall component(s) and the functional group(s) of FB involved in the LAB–FB interaction. Metho...

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