دانلود کتاب،مقاله،جزوه و نرم افزار مهندسی مواد
کلیه منابع مورد نیاز دانشجویان و مهندسین مواد (متالورژی ، سرامیک ، جوش ، خوردگی ، نانو و بایومواد)دانلود کتاب،مقاله،جزوه و نرم افزار مهندسی مواد
کلیه منابع مورد نیاز دانشجویان و مهندسین مواد (متالورژی ، سرامیک ، جوش ، خوردگی ، نانو و بایومواد)سنتز پودرهای نانوکامپوزیت نقره-اکسید قلع از روش هم رسوبی شیمیایی
Synthesis of silver tin oxide nanocomposite powders
via chemical coprecipitation method
سنتز پودرهای نانوکامپوزیت نقره-اکسید قلع از روش هم رسوبی شیمیایی
ABSTRACT
Introduction : Silver-metal oxide composite contact materials have a variety of applications in low voltage switches such as relays, contactors and circuit breakers . Until three decades ago, Ag-CdO composite was the preferred material for these usages due to excellent functional and technological properties. However, because of toxic nature of Cd, especially when it is evaporated, consider- able efforts have been made to replace it with environ-ment-friendly substances such as Ag-SnO2. Ag-SnO2 materials, in addition, have higher hardness, contact resistance and temperature rise than Ag-CdO substances. Besides their arc erosion and anti-welding properties are excellent.
خواص یک نانوکامپوزیت شفاف در برابر مادون قرمز
Properties of an Infrared-Transparent MgO:Y2O3 Nanocomposite
خواص یک نانوکامپوزیت شفاف در برابر مادون قرمز از نوع MgO:Y2O3
ABSTRACT
A 50:50 vol% MgO–Y2O3 nanocomposite with ~150 nm grain size was prepared in an attempt to make 3–5 lm infraredtransmitting windows with increased durability and thermal shock resistance. Flexure strength of the composite at 21°C is 679 MPa for 0.88 cm2 under load. Hardness is consistent with that of the constituents with similar grain size. For 3-mm-thick material at 4.85 lm, the total scatter loss is 1.5%, forward scatter is 0.2%, and absorptance is 1.8%. Optical scatter below 2 lm is 100%. Variable intensity OH absorption (~6% absorptance) is observed near 3 lm. The refractive index is ~0.4% below the volume-fraction-weighted average of those of the constituents. Thermal expansion is equal to the volumefraction- weighted average of expansion of the constituents. Specific heat capacity is equal to the mass-fraction-weighted average of heat capacities of the constituents. Thermal conductivity lies between those of the constituents up to 1200 K. Elastic constants lie between those of the constituents. The Hasselman mild thermal shock resistance parameter for the composite is twice as great as that of common 3–5 lm window materials, buthalf as great as that of c-plane sapphire.
