Effect of pH on the Microstructure and Purity of Copper-Coated Tungsten Composite Powders Prepared by Electroless Plating

2014 ◽  
Vol 616 ◽  
pp. 62-65
Author(s):  
Jing Ye ◽  
Wen Shu Chen ◽  
Qiang Guo Luo ◽  
Mei Juan Li ◽  
Qiang Shen ◽  
...  
Keyword(s):  
Grain Size ◽  
Oxygen Content ◽  
Electroless Plating ◽  
High Performance ◽  
Ph Value ◽  
Side Reactions ◽  
Composite Powders ◽  
Plating Bath ◽  
Effect Of Ph ◽  
Average Grain Size

High-performance copper-coated tungsten composite powders were successfully prepared using electroless plating at an appropriate pH in the plating bath. The effect of pH value in the plating bath on the microstructure and purity of the coated Cu layer was studied systematically. With the increase of pH in the bath, the surface roughness, particle size and average grain size of coated Cu increased, and the particle shape gradually changed from round into square block. At pH 12–12.5, coated Cu was highly pure with very little oxygen content (less than 0.09 wt.%). The promotion effect of the increased pH on both main electroless plating reaction and side reactions causes the changes of surface morphology, average grain size of Cu and the oxygen content in the composite powders.

MICROSTRUCTURE AND MAGNETIC PROPERTIES OF NANOSTRUCTURED Al2O3-20vol%Fe70Co30 COMPOSITE PREPARED BY HIGH ENERGY MECHANICAL MILLING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1383-1388 ◽  
Author(s):  
MASLEEYATI YUSOP ◽  
DELIANG ZHANG ◽  
MARCUS WILSON ◽  
NICK STRICKLAND
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Alloy Powder ◽  
Milling Time ◽  
High Energy ◽  
Composite Powders ◽  
Nanostructured Composite ◽  
Alloy Particles ◽  
Average Grain Size ◽  
Microstructure And Magnetic Properties

Al 2 O 3-20 vol % Fe 70 Co 30 composite powders have been prepared by high energy ball milling a mixture of Al 2 O 3 powder and Fe 70 Co 30 alloy powder. The Fe 70 Co 30 alloy powder was also prepared by mechanical alloying of Fe and Co powders using the same process. The effects of milling duration from 8 to 48 hours on microstructure and magnetic properties of the nanostructured composite powders have been studied by means of X-ray Diffractometry (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). It was found that the nanostructured composite powder particles with irregular shapes and Fe 70 Co 30 alloy particles being embedded in them formed after 8 hours of milling. The average grain size of the Al 2 O 3 matrix reduced drastically to less than 18nm after 16 hours of milling. On the other hand, the embedded alloy particles demonstrated almost unchanged average grain size in the range of 14-15nm. Magnetic properties of the powder compacts at room temperature were measured from hysteresis curves, and show strong dependence of the milling time, with the coercivity increasing from 67.1 up to 127.9kOe with increasing the milling time from 8 to 48 hours. The possible microstructural reasons for this dependence are discussed.

Synthesis of Nanocrystalline 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 Powder by a Citrate Method

2008 ◽  
Vol 368-372 ◽  
pp. 103-105
Author(s):  
Zhi Bin Tian ◽  
Xiao Hui Wang ◽  
Ji Li ◽  
Wei Zhao ◽  
Long Tu Li
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Traditional Method ◽  
Sintering Temperature ◽  
Ph Value ◽  
Precursor Solution ◽  
Milling Process ◽  
Citrate Method ◽  
Nano Powder ◽  
Average Grain Size

A citrate method to synthesize 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 nano-powder was studied. The stable gel was obtained by the control of the pH value and temperature of the precursor solution. The BNBT nano-powder was produced after calcining the xerogel at 600°C~800°C. The average grain size of the powder calcined at 700°C for 3 h is 50 nm, and the grain size of the ceramic sintered at 1080°C is 0.7 μm. The sintering temperature used is 100°C lower than the BNBT ceramic prepared by traditional method, but the electrical properties were comparable. In addition, it was found that the ball-milling process has important effect on the morphology of the ceramics and the orientation crystals were eliminated due to the disintegration of agglomerates during milling.

Electroless Silver Plating Process on Al-Ag Alloy Powder

2013 ◽  
Vol 800 ◽  
pp. 256-259
Author(s):  
Wang Qun ◽  
Ye Fan Li ◽  
Dong Mei Li ◽  
Zhi Xue Qu
Keyword(s):  
Electroless Plating ◽  
Alloy Powder ◽  
Glucose Solution ◽  
Silver Content ◽  
Silver Coating ◽  
Chemical Compositions ◽  
Composite Powders ◽  
Plating Bath ◽  
Thiourea Solution ◽  
Electroless Silver Plating

The Ag coating was deposited on the surface of Al-Ag alloy powder by electroless plating process. 10 wt% of AgNO3 was put in the powder for precursor replacement reaction, and then added the powder into electroless plating bath which contained glucose solution, solution of silver ammonia, thiourea solution, tartaric acid solution and absolute ethanol. The effects of formula components were analyzed. The surface morphology of the prepared composite particles was studied with SEM and their chemical compositions were confirmed by XRD. With the chemical etching method, silver content of the powder was determined. The studies have shown that an uniform, complete and dense silver coating for the Al-Ag composite powders was generated by this method, with the silver content being 20wt%, and the conductivity was favorable.

Electroless Plated Pd/GaAs Schottky Diode and its Application to Hydrogen Detection

2007 ◽  
Vol 124-126 ◽  
pp. 81-84
Author(s):  
Yen I Chou ◽  
Huey Ing Chen ◽  
Chien Kang Hsiung
Keyword(s):  
Grain Size ◽  
Oxide Layer ◽  
Schottky Diode ◽  
Electroless Plating ◽  
Sodium Ion ◽  
Bath Composition ◽  
Plating Bath ◽  
Hydrogen Detection ◽  
Hydrogen Sensing ◽  
Intermediate Oxide

In this study, the dependence of Pd/GaAs Schottky diode on the electroless plating (EP) variable is systematically studied. Both alkaline and acidic formulas for electroless Pd depositions are employed for investigations. The correlation between Pd gain size and the manipulation of plating bath composition is constructed. Experimental results show that the performances of Pd/GaAs Schottky diode, electric rectification and hydrogen detection, are largely governed by the Pd grain size. Furthermore, without the interference of sodium ion, the acidic-plated Pd/GaAs diode with intermediate oxide layer exhibits the excellent hydrogen sensing performances from 15 ppm to 1.0 % H2/air.

scholarly journals Electroless Plating of High-Performance Composite Pd Membranes with EDTA-Free Bath

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4894
Author(s):  
Jun-Yi Wang ◽  
Yen-Hsun Chi ◽  
Jin-Hua Huang
Keyword(s):  
Electroless Plating ◽  
High Performance ◽  
High Selectivity ◽  
Hydrogen Permeation ◽  
Low Cost ◽  
Cycling Stability ◽  
Plating Bath ◽  
High Hydrogen ◽  
High Performance Composite ◽  
Sequential Addition

High-performance composite Pd membranes were successfully fabricated using electroless plating with an EDTA-free bath. The plating started with employing the one-time addition of hydrazine. In the experiment, the hydrazine concentrations and plating bath volumes were systematically varied to optimize the plating. The optimum composite Pd membrane tube showed high H2 permeance of 4.4 × 10−3 mol/m2 s Pa0.5 and high selectivity of 1.6 × 104, but poor cycling stability. Then, a method of sequential addition of the hydrazine from the high to low concentrations was employed. The resultant membrane, about 6 μm thick, still exhibited a high selectivity of 6.8 × 104 as well as a much-improved plating yield and cycling stability level; this membrane outperformed the membrane made using the unmodified plating technique with the EDTA-contained bath. This result indicates the EDTA-free bath combined with the sequential addition of hydrazine is a simple, low-cost, yet effective method for preparing thin, dense composite Pd membranes featuring high hydrogen permeation flux and high thermal durability.

scholarly journals Effect of Content and Size of Reinforcements on the Grain Evolution of Graphene-Reinforced Aluminum Matrix Composites

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2550
Author(s):  
Qi Wu ◽  
Pengfei Cai ◽  
Lianchun Long
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
High Performance ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Pinning Effect ◽  
High Temperature Processes ◽  
Average Grain Size ◽  
Size And Morphology

Graphene-reinforced aluminum matrix composites (GRAMCs) attract great interest in industries due to their high performance potential. High-temperature processes such as sintering and aging are usually applied during the preparation of GRAMCs, leading to grain coarsening that significantly influences its properties. In this work, a modified 3D Monte Carlo Potts model was proposed to investigate the effect of content and size of graphene on the grain evolution during the heat treatment of GRAMCs. Grain growth with graphene contents from 0.5 wt.% to 4.5 wt.% and sizes from 5 μm to 15 μm were simulated. The grain growth process, final grain size and morphology of the microstructure were predicted. The results indicated that both the content and size of the reinforcements had an impact on the grain evolution. The pinning effect of grain size can be enhanced by increasing the content and decreasing the size of graphene. Agglomeration and self-contacting phenomena of the graphene arose obviously when the contents and sizes were relatively high. The average grain size decreased by 48.77% when the content increased from 0.5 wt.% to 4.5 wt.%. The proposed method and predicted regulations can provide a reference for the design and fabrication of GRAMCs.

PREPARATION OF ULTRAFINE W–Cu COMPOSITE POWDER USING ULTRASONIC-ASSISTED ELECTROLESS PLATING

2013 ◽  
Vol 27 (19) ◽  
pp. 1341004 ◽  
Author(s):  
LIMEI HUANG ◽  
LAIMA LUO ◽  
XIAOYU DING ◽  
XIANG ZAN ◽  
YU HONG ◽  
...  
Keyword(s):  
Growth Mechanism ◽  
Electroless Plating ◽  
High Performance ◽  
Room Temperature ◽  
Composite Powder ◽  
Surface Defects ◽  
Cell Structure ◽  
Reduction Reaction ◽  
Composite Powders ◽  
Ultrasonic Assisted

W – Cu ultrafine/nanocomposite powders have high sintering activity, so ultrafine/nanotechnology of W – Cu composite powders is one of the main methods to obtain fully dense, high-performance W – Cu composite materials. Cu -coated ultrafine W composite powders were synthesized by ultrasonic-assisted electroless plating process with non-noble metal activation pretreatment at room temperature in this paper. The growth mechanism of Cu layers and surface morphologies and composition of initial ultrafine W powders, pretreated W powders and Cu -coated W powders were analyzed by field emission scanning electron microscopy (FE-SEM), and energy dispersion spectrometry (EDS). The results show that the uniformly Cu coated W composite powder is successfully synthesized without conventional sensitization and activation steps by ultrasonic-assisted electroless plating at room temperature. The Cu layers on the ultrafine W powders had cell structure with dense, uniform distribution. The growth mechanism of Cu layers appears as follows: the surfaces of pretreated W powders appear linear-like and lamellar-like surface defects which act as activated sites. The reactants in the plating solution were adsorbed on catalytic activity surfaces of powders and happened oxidation–reduction reaction. The growth and aggregation mechanisms of Cu particles after nucleation are stripy Cu -cells grew up, bend, bifurcated, and aggregated, then wounding into a cellular structure, like "wrapping wool clusters" in the life. Finally, Cu cells grow up and merge into a layer.

scholarly journals Influence of synthesis conditions on microstructure and phase transformations of annealed Sr2FeMoO6−x nanopowders formed by the citrate–gel method

2016 ◽  
Vol 7 ◽  
pp. 1202-1207 ◽  
Author(s):  
Marta Yarmolich ◽  
Nikolai Kalanda ◽  
Sergey Demyanov ◽  
Herman Terryn ◽  
Jon Ustarroz ◽  
...  
Keyword(s):  
Grain Size ◽  
Phase Transformations ◽  
Ph Value ◽  
X Ray Diffraction ◽  
Gel Method ◽  
Synthesis Conditions ◽  
Average Grain Size ◽  
Different Temperatures ◽  
Synthesis Procedure ◽  
Crystal Lattice Parameters

The sequence of phase transformations during Sr2FeMoO6−x crystallization by the citrate–gel method was studied for powders synthesized with initial reagent solutions with pH values of 4, 6 and 9. Scanning electron microscopy revealed that the as-produced and annealed powders had the largest Sr2FeMoO6−x agglomerates with diameters in the range of 0.7–1.2 µm. The average grain size of the powders in the dispersion grows from 250 to 550 nm with increasing pH value. The X-ray diffraction analysis of the powders annealed at different temperatures between 770 and 1270 K showed that the composition of the initially formed Sr2FeMoO6−x changes and the molybdenum content increases with further heating. This leads to a change in the Sr2FeMoO6−x crystal lattice parameters and a contraction of the cell volume. An optimized synthesis procedure based on an initial solution of pH 4 allowed a single-phase Sr2FeMoO6−x compound to be obtained with a grain size in the range of 50–120 nm and a superstructural ordering of iron and molybdenum cations of 88%.

Microstructure and Magnetic Properties of Nd4.5Fe(76.5-x)B18.5Cu0.5Zrx Nanocomposite Permanent Magnetic Alloys

2007 ◽  
Vol 121-123 ◽  
pp. 1277-1280 ◽  
Author(s):  
Y. Qiao ◽  
Mao Cai Zhang ◽  
J. Zhu
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Exchange Coupling ◽  
High Performance ◽  
Magnetic Phase ◽  
Soft Magnetic ◽  
Phase Component ◽  
Average Grain Size ◽  
The Difference ◽  
Microstructure And Magnetic Properties

Nanocomposite Nd2Fe14B/Fe3B magnetic materials with high performance have been obtained by crystallizing over-quenched ribbons. The effect of addition element of Cu and Zr on the phase component, microstructure and magnetic properties of Nd4.5Fe（76.5-x）B18.5Cu0.5Zrx (x= 0.4, 0.5, 1.5, 2.0, 3.0, 4.0) has been systematically investigated. The average grain size of Nd2Fe14B phase and Fe3B phase for the different compositions were calculated from X-day diffraction pattern, which are in accordance with TEM micrographs. For the Nd4.5Fe77B18.5 ribbons, the average grain size of Nd2Fe14B and Fe3B were 34.2 nm and 51.7 nm, and for the Nd4.5Fe76.3B18.5Cu0.5Zr0.4 ribbons, they were only 36.5 nm and 37.1 nm, respectively. It has been found that the additions of Cu and Zr cause the reduction of the difference of grain size between the hard magnetic phase and the soft magnetic phase, that increase the exchange coupling between them. Therefore, it would lead to the magnetic properties improvement. It has been determined that Nd4.5Fe76.3B18.5Cu0.5Zr0.4 was the optimal composition, and the optimal magnetic properties were: Br= 1.204 T, Hci= 271 kA/m, and (BH)max =111.2 kJ/m3.

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