تهیه پودر ZrB2با اندازه نانو بوسیله سنتز خود انتشار دما بالا

Preparation of nano-size ZrB2 powder by self-propagating

high-temperature synthesis

تهیه پودر ZrB₂با اندازه نانو بوسیله سنتز خود انتشار دما بالا

ABSTRACT

Preparation of nano-size ZrB2 powder via SHS was demonstrated by adding 10–۵۰ wt.% NaCl into Zr–B elemental starting powder. Reactions took place completely even with high NaCl content. Adiabatic temperature of reactions, reaction wave velocity, average crystallite size and particle size of the formed ZrB2 decreased significantly with increasing NaCl content. ۳۰ wt.% NaCl addition was found to be the optimum and obtained ZrB2 particles were mostly finer than 200 nm. Hindrance of mass transport among ZrB2 crystals is believed to be  the basis of grain refinement effect of NaCl. Obtaining nano-sized powder was considered very difficult in SHS due to inevitable high temperatures. Owing to the introduction of NaCl into SHS, process control and preparation of ceramic powder having nano-sized particles were rendered possible. The development has the potential to enrich the spectrum and the properties of materials that could be produced via SHS.

آماده سازی سرامیک های دی براید زیرکونیوم

Preparation of zirconium diboride ceramics by reactive spark
plasma sintering of zirconium hydride–boron powders

آماده سازی سرامیک های دی براید زیرکونیوم به کمک واکنش سینتر کردن پلاسمای جرقه ایِ  پودرهای هیدرید زیرکونیوم-بور

ABSTRACT

Monolithic ZrB2 ceramics were prepared by reactive spark plasma sintering of a ZrH2–B mixture at 1650–۱۸۰۰ C. The microstructure of the resulting ZrB2 ceramics were characterized by X-ray diffractometry and scanning electron microscopy. The ZrH2–B mixture converted completely into ZrB2 without trace quantities of residual ZrH2 and B. Highly dense ZrB2 was obtained at 1750 C or above. The elastic moduli, flexural strength, thermal and electrical conductivities were comparable with those of ZrB2 ceramics obtained by sintering conventional ZrB2 powders