A study on barium ferrite particles prepared by chemical coprecipitation

2000 ◽  
Vol 15 (10) ◽  
pp. 2151-2156 ◽  
Author(s):  
W. K. Ng ◽  
J. Ding ◽  
Y. Y. Chow ◽  
S. Wang ◽  
Y. Shi
Keyword(s):  
Heat Treatment ◽  
Barium Ferrite ◽  
Room Temperature ◽  
Fine Particles ◽  
High Coercivity ◽  
Weak Anisotropy ◽  
Chemical Coprecipitation ◽  
Dispersed Particles ◽  
Dispersing Agent ◽  
Different Temperatures

Chemical coprecipitation was employed to prepare fine particles of barium ferrite with high coercivity (450 kA/m). Magnetic properties of the bonded barium ferrite magnet were measured at different temperatures. The results were found to be fairly close to the theoretical values based on the Stoner–Wohlfarth model. Mechanical milling was utilized to prepare ultrafine dispersed barium ferrite particles. NaF was introduced as a dispersing agent during milling and subsequent heat treatment. The dispersed particles were compacted and then subjected to die upsetting at room temperature. A weak anisotropy in the coercivity and remanence was found in the directions parallel and perpendicular to the compaction direction.

Effect of Heat Treatment on Mechanical and Setting Properties of TTCP-Based Calcium Phosphate Cement

2019 ◽  
Vol 798 ◽  
pp. 59-64
Author(s):  
Kannaporn Pooput ◽  
Korkiat Sedchaicharn ◽  
Anek Phuchamnong ◽  
Woranan Petcharoen
Keyword(s):  
Heat Treatment ◽  
Calcium Phosphate ◽  
Room Temperature ◽  
Liquid Content ◽  
Tetracalcium Phosphate ◽  
Setting Reaction ◽  
Setting Times ◽  
Preheating Temperature ◽  
Different Temperatures ◽  
Cement Setting

The objective of this study was to investigate the effect of heat treatment on setting reaction and mechanical properties of tetracalcium phosphate (TTCP) and dicalcium phosphase (DCP)-based calcium phosphate cements. CPC pastes were prepared at room temperature and heated at different temperatures (from 37 to 60°C) for 10 min. Then, the preheated CPC pastes were rapidly cooled down to room temperature before further heated at 37°C until they set. Three different CPC formulations prepared from different particle sizes of TTCPs were used for the investigation. From the study, it was found that preheating could accelerate setting reaction for all CPCs according to increasing speed of hydroxyapatite (HA) conversion. The higher the preheating temperature, the faster the cements could set. However, at preheating temperature higher than 60°C longer cement setting times were observed. It may be that at high temperature some liquid content in the CPC paste evaporated, resulting in slow setting reaction rate. Compressive strengths of the cements after immersion in simulated body fluid (SBF) for 7 days increased as a result of an increase of HA conversion.

Effect of Heat Treatment on the Properties of Inconel X-750

2005 ◽  
Vol 297-300 ◽  
pp. 1220-1222
Author(s):  
Shi Chang Cheng ◽  
Zhao Jie Lin ◽  
Gang Yang ◽  
Zheng Dong Liu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solid Solution ◽  
Impact Toughness ◽  
Room Temperature ◽  
Solution Treatment ◽  
Heat Treatments ◽  
Air Cooling ◽  
Solid Solution Treatment ◽  
Different Temperatures

The authors experimentally investigated the change of mechanical properties of Inconel X-750 alloy under various heat treatments. For the selected specimens, solid solution treatment under different temperatures was carried out, followed air cooling or furnace cooling. Results show that suitable solid solution treatment and air cooling enhances the strength, plasticity, impact toughness at room temperature of the alloy and lowers the hardness of the alloy at room temperature.

Microstructure Evolution of AS21 Magnesium Alloy via the SIMA Process

2012 ◽  
Vol 706-709 ◽  
pp. 1146-1151 ◽  
Author(s):  
Majid Bigdeli Karimi ◽  
Mostafa Hajian Heidary ◽  
Javad Samei ◽  
Daniel E. Green
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Microstructure Evolution ◽  
Fine Particles ◽  
Salt Bath ◽  
Semisolid Processing ◽  
Mean Grain Size ◽  
Different Temperatures ◽  
Sima Process ◽  
Carbonate Salt

ASis a relatively new series of Magnesium alloys. The microstructure of this alloy can be improved for semisolid processing. The current research is concerned with the microstructure evolution of AS21 under the strain induced melt activated (SIMA) process. For this purpose, the AS21 alloy is cast and compressed 10-40% at 200 °C. The semisolid heat treatment is completed in a carbonate salt bath at different temperatures between 600-620 °C. The microstructure studies show that there is no favourable microstructure evolution between 600-610 °C. At 615 °C fine globular grains are obtained with the most desired mean grain size and sphericity of 67 µm and 81%, respectively. At 620 °C an undesirable coarsening phenomenon occurs that damages the microstructure globularity. SEM micrographs show that in a successful SIMA processing, the Mg2Si phases are broken into fine particles distributed within the grains and grain boundaries.

scholarly journals STUDY OF THE STRUCTURE AND PROPERTIES OF LEAD-FREE RAPIDLY SOLIDIFIED ZINC-BASED ALLOYS DURING A HEAT TREATMENT

2021 ◽  
pp. 672-681
Author(s):  
Денис Александрович Зерница ◽  
Василий Григорьевич Шепелевич
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Zinc Concentration ◽  
Second Phase ◽  
Particle Sizes ◽  
Dispersed Particles ◽  
Solution Proceeds ◽  
Melt Cooling ◽  
Rapidly Solidified ◽  
Tin Content

Представлены результаты исследований влияния сверхвысоких скоростей охлаждения расплава, равных не менее 10К/с, на свойства быстрозатвердевших сплавов системы Zn - Sn. Верхняя область фольги, контактирующая с кристаллизатором в процессе затвердевания, имела дисперсные частицы второй фазы, и по мере удаления от верхних слоёв размеры частиц укрупнялись. При комнатной температуре протекает распад пересыщенного твёрдого раствора с выделением дисперсных частиц. Дополнительная термическая обработка приводит к укрупнению частиц второй фазы, и способствует снижению микротвёрдости. Быстрозатвердевшие фольги с максимальной концентрацией цинка характеризуются наличием текстуры (0001), которая по мере увеличения содержания олова в цинке ослабляется, и при легировании выше 20 мас. % Sn происходит перестройка на текстуру (101̅0). Термическая обработка до 160 °С не приводит к изменению текстуры. The results of studies of the effect of ultrahigh melt cooling rates, equal to at least 10 K/s, on the properties of rapidly solidified alloys of the Zn - Sn system are presented. The upper region of the foil, in contact with the crystallizer during solidification, had more dispersed particles of the second phase, and as the distance from the upper layers increased, the particle sizes increased. At room temperature, the decomposition of a supersaturated solid solution proceeds with the release of dispersed particles. Additional heat treatment leads to the coarsening of the particles of the second phase, and helps to reduce the microhardness. Rapidly solidified foils with a maximum zinc concentration are characterized by the presence of a (0001) texture, which weakens as the tin content in zinc increases, and upon alloying up to 30 wt. % Sn is rearranged to (101̅0) texture. Heat treatment up to 160 °C does not change the texture.

Annealing Effect on Microstructure and Coercivity of YCo5 Nanoparticles Obtained by Mechanical Milling

2009 ◽  
Vol 68 ◽  
pp. 122-126
Author(s):  
José Trinidad Elizalde Galindo ◽  
Reiko Sato Turtelli ◽  
Roland Grössinger ◽  
José Andrés Matutes-Aquino
Keyword(s):  
Heat Treatment ◽  
Exchange Interaction ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Hysteresis Loops ◽  
Annealing Effect ◽  
Subsequent Heat Treatment ◽  
High Coercivity ◽  
Crystallite Sizes

Nanocrystalline YCo5 powders with high coercivity were prepared by mechanical milling and subsequent heat treatment at 820 °C for different annealing times, ta = 2.5, 3.0, 3.5 and 4.5 min, obtaining average crystallite sizes of <D>  17, 19, 32 and 39 nm., respectively. The coercivity values were determined from the hysteresis loops measured at maxima fields of Hm = 5 and 20 T. The highest coercivity was obtained for the sample exhibiting <D>  19 nm, where at room temperature and Hm = 5 T, the coercivity value is of 9.0 kOe. At 77 K and Hm = 5 T, the coercivity increase to 11.8 kOe and for Hm = 20 T, a higher value such as 13.1 kOe was found. The Ms/Mr ratio is enhanced to 0.62 indicating the occurrence of exchange interaction among nanocrystalline magnets.

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