Electroless nickel-phosphorus coating on Ti and Al elemental powders
About: This article is published in Scripta Materialia.The article was published on 2001-07-31. It has received 32 citations till now. The article focuses on the topics: Electroless nickel & Metal powder.
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TL;DR: In this paper, an optimized plating carousel design is proposed which can facilitate the release of H2 gas and reduce such circular pits, and the computational fluid dynamics simulations have found that the plating fluid has vortex flow around the disks and the gas bubbles have a high possibility to attach to the disk surface.
Abstract: In this study, a typical circular pit of electroless Ni–P coating has been investigated with atomic force microscopy (AFM), nanoindentation, and focused ion beam-scanning electron microscopy (FIB-SEM). It is found that the land area of the circular pit has lower hardness than the good surface, and there is a spherical-crown-shaped boundary between the pit and the coating. The formation mechanism of such defects is because the H2 gas bubble generated by the chemical reaction attaches to the plating surface and stops the Ni–P growth on such area, and after the bubble is released the Ni–P starts to grow again and forms a new germination phase. The computational fluid dynamics (CFD) simulations have found that the plating fluid with current plating carousel design has vortex flow around the disks and the H2 gas bubbles have a high possibility to attach to the disk surface. An optimized plating carousel design is proposed which can facilitate the release of H2 gas and reduce such circular pits.
10 citations
TL;DR: In this paper, a novel hydrothermal coating process was developed to deposit amorphous Ni(OH)2·H2O over octahedral α-Fe2O3 particles by treating aqueous dispersion of the preformed cores in Ni(NO3)2/CH3COONa solution.
9 citations
TL;DR: In this paper, the Ni plated Ti powder was characterised by scanning electron microscopy, energy dispersive spectrometer analysis and X-ray fluorescence, and it was found that a pure/uniform Ni layer may be deposited on the Ti powder particles.
Abstract: In this study, Ti powder (average size: 45 μm) was plated/coated by electroless Ni with hydrazine hydrate as reductant. The Ni plating was carried out at 85°C and pH 9–10. The influence of process parameters such as plating period as well as reductant concentration was investigated. The Ni plated Ti powder was characterised by scanning electron microscopy, energy dispersive spectrometer analysis and X-ray fluorescence. It is found that a pure/uniform Ni layer may be deposited on the Ti powder particles. The deposited mass increases as plating period/reductant concentration increases.
8 citations
01 Jun 2018
TL;DR: In this paper, a method to synthesise reactive nickel-aluminium core-shell structures via a two-step plating process is described, based on an electroless process, the natural oxide layer of the aluminium particles is removed and substituted with a thin layer of nickel.
Abstract: Reactive particles represent a promising alternative for effectively joining components with freeform surfaces and different material properties. While the primary application of reactive systems is combustion synthesis for the production of high-performance alloys, the highly exothermic reaction can also be used to firmly bond thermosensitive joining partners. Core-shell structures are of special interest, since they function as separate microreactors. In this paper, a method to synthesise reactive nickel-aluminium core-shell structures via a two-step plating process is described. Based on an electroless process, the natural oxide layer of the aluminium particles is removed and substituted with a thin layer of nickel. Subsequently, the pre-treated particles are electroplated with nickel. The high reactivity of aluminium and the oxide layer play a significant role in adjusting the process parameters of the Watts bath. Additionally, the developed experimental set-up is introduced and the importance of process control is shown. In order to achieve reproducible results, the electroplating process was automated. Ignition tests with electromagnetic waves demonstrated that the particles undergo an exothermic reaction. Therefore, they can be used as a heat source in thermal joining applications.
7 citations
References
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01 Jan 1985
TL;DR: In this article, the authors describe the behavior of grain boundaries in a two-dimensional model ordered alloy and the effects of elastic anisotropy on the anomalious yield behavior of cubic ordered alloys.
Abstract: This book contains over 50 selections. Some of the titles are: Order-disorder behavior of grain boundaries in a two-dimensional model ordered alloy; Dislocation reactions at grain boundaries in Ll/sub 2/ ordered alloys; Creep cavitation in a nickel aluminide; Effects of elastic anisotropy on the anomalious yield behavior of cubic ordered alloys; and Processing technology for nickel aluminides.
2,123 citations
Book•
30 Jun 1985TL;DR: The electron microscopy with light and electrons (EM) family as discussed by the authors is a family of microscopy techniques that use electron microscopes for high-vacuity measurements. But the electron microscope family is not suitable for the analysis of high-voltage measurements.
Abstract: 1. Microscopy with light and electrons 2. The electron microscope family 3. Rudiments of specimen preparation and interpretation of micrographs 4. Specialised techniques in electron microscopy 5. Examples of the use of electron microscopy Appendix 1: Production and measurement of high vacua Appendix 2: Vacuum deposition of thin metallic and carbon films for electron microscopy Appendix 3: X-ray generation and analysis Appendix 4: Electron sources for electron microscopes.
170 citations
TL;DR: In this paper, the effects of Cr additions to y-base alloys have been investigated, using bulk materials consolidated from rapid solidification-processed ribbons, and it was concluded that the ductilization effect of Cr in duplex alloys is partially due to the tendency of Cr to occupy Al lattice sites.
Abstract: The effects of Cr additions to y-base alloys have been investigated, using bulk materials consolidated from rapid solidification-processed ribbons. The composition ranges studied were 0 to 4 at. pet Cr and 44 to 54 at. pet Al. It was found that Cr additions do not affect the deformation behavior of single-phase γ alloys. However, they significantly enhance the plasticity of Al-lean duplex alloys which contain grains of single-phase γ and grains of lamellar γ/α2. Other Cr effects on microstructure, phase stability, site occupancy, and deformation sub-structures were characterized and correlated to the observed mechanical behavior. It was concluded that the ductilization effect of Cr in duplex alloys is partially due to the tendency of Cr to occupy Al lattice sites. Ductilization is also partially due to the ability of Cr to modify the Al partitioning and, therefore, the thermal stability of transformed α2 laths.
158 citations
TL;DR: In this article, the ternary alloys of arc-melted, nearequiatomic TiAl alloys containing boron additions are analyzed and compared with those of binary Ti-Al and Ti-B alloys processed in a similar fashion.
Abstract: Solidification microstructures of arc-melted, near-equiatomic TiAl alloys containing boron additions are analyzed and compared with those of binary Ti-Al and Ti-B alloys processed in a similar fashion. With the exception of the boride phase, the matrix of the ternary alloy consists of the same α2 (DO19) and γ (Ll0) intermetallic phases found in the binary Ti-50 at. pct Al alloy. On the other hand, the boride phase, which is TiB (B27) in the binary Ti-B alloys, changes to TiB2 (C32) with the addition of Al. The solidification path of the ternary alloys starts with the formation of primary α (A3) for an alloy lean in boron (∼1 at. pct) and with primary TiB2 for a higher boron concentration (∼5 at. pct). In both cases, the system follows the liquidus surface down to a monovariant line, where both α and TiB2 are solidified concurrently. In the final stage, the α phase gives way to γ, presumably by a peritectic-type reaction similar to the one in the binary Ti-Al system. Upon cooling, the α dendrites order to α2 and later decompose to a lath structure consisting of alternating layers of γ and α2.
109 citations