Equiaxed Nd–Fe–B fine powder with high performance prepared by mechanical alloying

2007 ◽  
Vol 101 (9) ◽  
pp. 09K502 ◽  
Author(s):  
Jingzhi Han ◽  
Shunquan Liu ◽  
Xiaodong Zhang ◽  
Honglin Du ◽  
Changsheng Wang ◽  
...  
2006 ◽  
Vol 88 (9) ◽  
pp. 092104 ◽  
Author(s):  
Heng Wang ◽  
Jing-Feng Li ◽  
Ce-Wen Nan ◽  
Min Zhou ◽  
Weishu Liu ◽  
...  

2004 ◽  
Vol 87 (1) ◽  
pp. 238-243 ◽  
Author(s):  
Marilena D'Amato ◽  
Giovanni Forte ◽  
Sergio Caroli

Abstract A study was undertaken to develop a method for the chemical speciation of As in rice on the basis of current knowledge in this field for use in preparing a certified reference material (CRM). Samples of the Arborio rice variety were ground to a fine powder, which was extracted under sonication with a water–methanol mixture (1 + 1, v/v). The resulting solutions were injected into a high-performance liquid chromatograph combined on-line with a quadrupole inductively coupled plasma–mass spectrometer. This hyphenated system allowed for the quantification of As species in one analytical step. Four forms of As were detected: inorganic As (III), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), and inorganic As (V) at concentrations of 88.2 ± 7.1, 50.8 ± 5.0, 15.2 ± 1.7, and 51.2 ± 3.5 ng/g, respectively. The concentration of total As was 211 ± 7 ng/g. The limits of detection (3σ criterion) and the quantitation (10σ criterion) were, respectively, as follows (in ng/g): As (III), 0.095 and 0.320; As (V), 0.082 and 0.273; MMA, 0.110 and 0.367; and DMA, 0.145 and 0.480. Ten hours were needed for the extraction procedure, 6 h for the evaporation, and 30 min for quantification of the analytes. This investigation was performed in the frame of a European Commission Project on the feasibility of CRMs for As and Se species.


Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1354
Author(s):  
Yang Tang ◽  
Zheguan Huang ◽  
Jianming Yang ◽  
Yonglin Xie

Binder jet 3D printing (BJ3DP) is an additive manufacturing technology that selectively deposits binder on powder to form a three-dimensional green body followed by sintering process. The low strength of green body and metallurgical issues limit the manufacture of Ti6Al4V parts with high-performance and that are lightweight. In this study, thermal-bubble inkjet technology was used to print Ti6Al4V parts via jetting low-concentration in-situ polymer binders. In addition, a method for mixing fine powder was used to enhance the capillary force of the powder bed and mechanical properties of the parts. The results show that the capillary force was enhanced from 8.35 kPa for pure powder to 16.27 kPa for mixed powder by mixing fine powder. The compression strength of green body was enhanced from 1.5 MPa to 3.21 MPa. After sintering, the sample with mixed powder sintered at 1420 °C for 2 h had achieved a maximum density of 95.2%, microhardness of 316 HV, and yield stress of 589 MPa. The relative density of 95.2% of Ti6Al4V parts fabricated by BJ3DP technology in our study is significantly higher than the value reported in the existing literature. Finally, the porous structure with a size of 550 μm was fabricated. Results presented demonstrate that BJ3DP can produce Ti6Al4V parts with excellent properties.


2014 ◽  
Vol 629-630 ◽  
pp. 218-222
Author(s):  
Lin Xu

Concrete has a high performance corrosion resistance, with the choice of the thickness of the active alkali aggregate,grain shape structured,well-graded,small porosity. Superfine cement with mineral powder instead of 30% to 50%, mineral superfine powder participate hydration, solve concrete interface structure Ca (OH)2enrichment and directional crystallization problems, improve the coagulation. The internal structure of the soil, improving the strength and density of concrete. Meanwhile ultra-fine powder mixed with minerals, reducing the C3A content in the powder and the concrete in the late ettringite hazards greatly. Improve the corrosion resistance of concrete, with also improve the internal structure of concrete and the strength of concrete, compactness and corrosion resistance. Composite type superplasticizer, reducing water consumption unilateral concrete, air-entraining agent is added to improve the density of concrete, the concrete has good impermeability and frost resistance. On the use of ordinary portland cement, it gets high performance, by the ratio test, developed the corrosion and frost resistance of concrete for the chloride, sulfate alone or jointly under the action of the environment concrete structures in corrosive environments, such as coastal areas, inland lakes, underground sewage or chemical zones, there are concrete structure durability requirements, with good economic and promotional value.


Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1250 ◽  
Author(s):  
Yonggang Tong ◽  
Peibu Qi ◽  
Xiubing Liang ◽  
Yongxiong Chen ◽  
Yongle Hu ◽  
...  

Different-shaped ultrafine MoNbTaW high-entropy alloy powders were firstly prepared by a convenient mechanical alloying method. The phase composition and microstructure of the powders were characterized. The powders are ultrafine with nano-sized grains and a good homogeneous microstructure. All the powders have a single body-centered cubic solid solution phase and form the high-entropy alloy during mechanical alloying. These powders with different shapes are quite attractive for developing high-performance MoNbTaW high-entropy alloy bulk and coatings combined with a following sintering, spraying, or additive manufacturing technique.


2010 ◽  
Vol 107 (9) ◽  
pp. 09A730 ◽  
Author(s):  
Zhongmin Chen ◽  
David Miller ◽  
Jim Herchenroeder

Author(s):  
Tejavathi Dh ◽  
Sujatha Bs ◽  
Kannan R

  Objective: To estimate the contents of curcuminoids in two samples of Curcuma karnatakensis collected from different localities.Methods: Quantification of curcuminoids was estimated by ultra-high performance liquid chromatography-mass spectrometry/selected reaction monitoring (UHPLC-MS/SRM) method in two samples of C. karnatakensis for the first time. Fine powder of rhizomatous rootstocks of two plant samples collected from different habitats were served as Samples A and B. The MS used for the metabolite analysis is a Vantage TSQ triple stage quadrupole MS equipped with heated electrospray ionization. The MS is coupled with an Agilent 1290 infinity UHPLC system. A stock solution of curcuminoid standard was prepared by dissolving 5 mg of standard in 1 mL of methanol. Seven different concentrations of standard (0.15-10 ng on column) were injected for the UHPLC-MS/SRM analysis. Separations were performed using a C-18 column with a flow rate of 0.2 mL/minute.Results: Contents of curcumin, demethoxycurcumin, and bisdemethoxycurcumin were found to be varied in two samples and lowest than any other species of Curcuma studied. Variation in the contents may be due to their different habitats in which they are growing.Conclusion: The present attempt of analyzing the contents of curcuminoids in this endemic taxon for the first time will provide the basis for further pharmacological analysis to authenticate the efficacy of these active principles as the curcuminoids are known for varied pharmacological activities.


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