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Magnetizable Fluids
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
Tom Black, J. David Carlson, Daniel E. Barber
The most widely used material for MR fluid particles is carbonyl iron. Carbonyl iron is the common name given to iron particles formed from the thermal decomposition of iron pentacarbonyl. Carbonyl iron powder is elemental iron (Fe) with more than 98% iron content. Key physical properties of carbonyl iron powder are the very spherical shape of the particles and the fine particle size in the 1 to 10 μm range. Reduced grades of carbonyl iron powder are available that have most of the residual oxygen, carbon, and nitrogen removed, resulting in particles with iron contents greater than 99.5% that are mechanically soft and have excellent magnetic properties [43,44]. Other forms of elemental iron powder, such as water atomized or electrolytic, are also possible. While generally less expensive than carbonyl iron powder, the larger size of these other forms (10 to 100 μm) and more irregular particle shape make them more difficult to use. On the other hand, while particles less than less than 1 μm would be easier to maintain in suspension, elemental iron particles smaller than 1 μm are not available as a commodity material.
Nanoparticulate Nanocarriers in Drug Delivery
Published in Anil K. Sharma, Raj K. Keservani, Rajesh K. Kesharwani, Nanobiomaterials, 2018
Raj K. Keservani, Anil K. Sharma, Rajesh K. Kesharwani
The sources of magnetic material used in combination therapy usually Iron oxides with core/shell structure (Drbohlavova et al., 2009). Iron oxides have several crystalline phases or polymorphs viz., Fe2O3 (magnetite), α-Fe2O3 (hematite), γ-Fe2O3 (maghemite), β-Fe2O3, ε-Fe2O3, and some others, form due to high pressure (Zboril et al., 2002). Among all the Iron oxides, only two (magnetite and maghemite) found the greatest importance in bioapplications (Tucek et al., 2006). The well-known small size material, carbonyl iron with a unique form of elemental iron was also used as magnetic core (Reshmi et al., 2009).
Electromagnetic wave absorption and bending properties of double-layer honeycomb 3D woven composites: experiment and simulation
Published in The Journal of The Textile Institute, 2023
Rongrui Wang, Wendi Liu, Xinghai Zhou, Yuan Gao, Liwei Wu, Lihua Lyu
A mixed solution of epoxy resin containing carbonyl iron powder and carbon black, stirred well and ultrasonically dispersed for 10 min, had a mass ratio of carbonyl iron powder, carbon black, resin, and curing agent of 4:0.03:4:3.2. After curing, the material was heat-set at 90 °C for 2 h, 130 °C for 1 h, and 150 °C for 4 h. The vacuum-assisted resin transfer moulding (VARTM) process, was simple to use, convenient, and inexpensive (Yin et al., 2022). To prevent the VARTM moulding process from altering the thickness of the fabric, a rigid polyurethane foam is added to the holes in the double-layer honeycomb 3D woven electromagnetic wave absorbing fabric, which can ensure the thickness. The double-layer honeycomb 3D woven electromagnetic wave absorbing composite preparation process is shown in Figure 4, and the diagram is shown in Figure 5. Table 4 also shows the theoretical and actual weights of double-layer honeycomb 3D woven electromagnetic wave-absorbing fabrics and composites.
Microstructure and mechanical properties of high carbon M2 powder metallurgy high-speed steel prepared by the carbide addition
Published in Powder Metallurgy, 2022
Junhao Yang, Rutie Liu, Xiang Xiong, Huaizhuang Luan, Yanrong Hao, Baozhen Yang, Jie Chen
In this work, high-carbon (carbon saturation A≈1) M2 PM HSS was prepared using carbonyl iron powder and carbide as raw materials. Compared with atomised iron powder, the fine particle size of the carbonyl powder promotes sintering which in turn helps increase the density [16]. Another noteworthy problem is the existence of stable oxides on the surface of atomised pre-alloyed HSS powder due to the higher oxygen affinity elements such as Cr, V [5,17]. These stable oxides may strongly inhibit the formation of stable metallic sintering bridges and increase the amount of residual oxygen. Using carbides as alloy element carrier can not only avoid the oxidation of active metals during milling and sintering, but also curb grain growth due to the pinning effect of undissolved carbides during sintering. In the course of experiment, mechanical ball milling and vacuum sintering were used to improve the sinterability, and the relationship between its performance and the evolution of microstructure characteristics was emphatically studied.
Development of Al2O3-SiO2 based magnetic abrasive by sintering method and its performance on Ti-6Al-4V during magnetic abrasive finishing
Published in Transactions of the IMF, 2021
S. Ahmad, R. M. Singari, R.S. Mishra
X-ray analysis for sintered magnetic abrasive powder was conducted to examine the structural changes during the annealing process. The X-ray diffraction spectrum of the SMA is shown in Figure 8. The alumina (Al2O3) peaks of the abrasive powder are collected in a mixture of carbonyl iron powder along with fine Al2O3 and SiO2 particles, and SiO2 peaks are covered in the background due to the presence of a marginal amount of SiO2 particles. In addition to the prominent ferrite peaks, the X-ray diffraction of the SMA, i.e. composite powder, reveals that minor peaks of cementite, hematite, cohenite, magnetite, α- Fe-iron, and β- Fe-iron are obtained. A part of the carbon particles found in carbonyl iron powder is thought to result in the formation of iron carbides during annealing. Therefore, the formation of Fe3O4 is observed, suggesting that the presence of oxygen in the chamber oxidises the composite material.