Tin Powder Research Articles

Effects of Y2O3–RE2O3 (RE = Sm, Gd, Lu) additives on electrical and mechanical properties of SiC ceramics containing Ti2CN

Dense SiC–Ti2CN composites were fabricated from β-SiC and 4vol% TiN powders with 2vol% equimolar Y2O3–RE2O3 (RE=Sm, Gd, Lu) additives by conventional hot pressing. Electrical and mechanical properties of the SiC–Ti2CN composites were investigated with a variation of sintering additive composition. Relative densities of ∼99.9% were achieved for all specimens. All specimens exhibited electrical resistivities on the order of ∼10−5Ωm. These low electrical resistivities were attributed to heavy nitrogen doping in the SiC lattice (carrier density ∼1020cm−3). Typical electrical resistivity, flexural strength, fracture toughness, and Vickers hardness values of the SiC–Ti2CN composite sintered with 2vol% Y2O3–Lu2O3 additives were 2.2×10−5Ωm, 722MPa, 4.6MPam1/2, and 25GPa, respectively.

Electro-sinter-forged Ni–Ti alloy

An innovative powder metallurgical process (Electro-Sinter-Forging – ESF) has been applied to a gas atomized Ni–Ti powder to avoid the typical drawbacks of the conventional industrial processing of this material: oxygen pick up, high processing temperature and slow cooling rate. At the same time, the ESF allows to overcome the low sintering activity of the Ni–Ti powders. Sintered materials, produced by using different processing conditions, are characterized and compared. Results concerning the thermal, structural, microstructural and mechanical analyses are reported and discussed. The density of the sintered samples increases by increasing the amount of applied energy and final pressure during the sintering process. The sample showing the highest density has a direct phase transformation on heating and cooling, with broad DSC peaks, and small thermal hysteresis; it is austenitic at room temperature, with a low amount of coarse (micrometric) precipitates, Ti4Ni2Ox nanometric precipitates and high hardness. The ESF sintering at highest energies induces a “band-type” microstructure with a preferential crystallographic orientation; the crystallographic texture of the sintered samples has been investigated through Electron Back Scattering Diffraction (EBSD) analysis and a fiber texture <100> has been evidenced. The ion release from the sintered samples has been investigated: it is comparable to commercial Ni–Ti alloys currently used and it is correlated to the sample porosity. The biocompatibility has been demonstrated towards fibroblasts.

Effect of Solvent Chelating on Crystal Growth Mechanism of CZTSe Nanoink in Polyetheramine

This paper reports on the reaction mechanism of Cu2ZnSnSe4 (CZTSe) nanoink via a solvent-thermal reflux method using copper (Cu), zinc (Zn), tin (Sn), and selenium (Se) powders as precursors and polyetheramine as a reaction solvent. The formation of CZTSe nanoparticles in polyetheramine began with the formation of binary phase CuSe2 due to the strong catalysis provided by polyetheramine. This was followed by the formation of binary phase ZnSe crystals. In the final stage, ternary crystals of Cu2SnSe3 transformed into well-dispersed nanocrystals of Cu2ZnSnSe4, which are derived from the characterization of XRD, Raman, and TEM. The size of the crystals was shown to decrease with reaction time due to the emulsification effect of the polyetheramine epoxy group. Quaternary phase CZTSe first appeared at 20 h, and then the composition of the CZTSe tended to become Cu-poor and Zn-rich over time. The proposed reaction mechanism of CZTSe nanoparticles in polyetheramine presented a distinct phase transformation and suitable time-composition properties, which benefited to further solution-based solar cell application.

Superelasticity of NiTi–Nb metallurgical bonding via nanoindentation observation

Sandwich architecture with cross-shape periodic cellular cores is synthesized via eutectic reaction between NiTi and Nb powder, such forming metallurgical bonding between NiTi wires near eutectic reaction temperature. Superelasticity is investigated systematically via nanoindentation tests. The Ti-rich phase is weaker in superelastic recovery comparing with that of Nb-rich phase, lamellar and rod-like NiTi–Nb eutectic. Inconsistent Nb element distribution in the interface of eutectic area and NiTi wire enhances the martensitic transformation.

Microstructures and properties of TiN reinforced Co-based composite coatings modified with Y2O3 by laser cladding on Ti–6Al–4V alloy

In this study, TiN reinforced composite coatings were fabricated on Ti–6Al–4V substrate by laser cladding with Co42 self-fluxing alloy, TiN and Y2O3 mixed powders. Microstructures and wear resistance of the cladding coatings with and without Y2O3 addition were investigated comparatively. Results showed that the coatings were mainly comprised of γ-Co/Ni, TiN, CoTi, CoTi2, NiTi, TiC, Cr7C3, TiB, Ti5Si3 and TiC0.3N0.7 phases. The coatings showed metallurgical bonding free of pores and cracks with the substrate. Compared with the Ti–6Al–4V substrate, the microhardness and wear resistance of the coatings was enhanced by 3–4 times and 9.5–11.9 times, respectively. With 1.0 wt.% Y2O3 addition, the microstructure of the coating was refined significantly, and the microhardness and dry sliding wear resistance were enhanced further. The effects of Y2O3 were attributed to the residual Y2O3 and decomposed Y atoms.

Effect of Fabrication Method by Powder Metallurgy on Frangibility Green Bullet Cu-10%Sn as Eco-Friendly Bullet

The bullet is used for immobilize object. However it can harm the shooter because it can be ricochet. Thus it, we develop frangible bullet which can be broken when hit the hard target. Conventional bullets are made of lead base material which poison. Therefore frangible bullet does not use lead as base material, so it is classified as green bullet. Green bullet is made by powder metallurgy method. Powder metallurgy process are measuring copper and tin powder, dry mixing, and compacting 600 Mpa in pressure for 10 minutes in holding time, and sintering at 300, 500, 700°C for 0,5; 1; and 1,5 hours in holding time. Then, measure the sinter density and analyze the sample by XRD and SEM-EDX. Based on experiment, we found that the bullet Cu-10%wt which sintering 500 °C in temperature for 1 hour has the best frangibility. The highest theoretical density , compression strength, and hardness are 8.8 gr/cm3, 280.45 MPa, 60.67 HRF. The observer result by scanning electron microscope showed that the phase homogeneity at sintering temperature 500°C for 1 hour in holding times was better than the other variable. By observing phase formed, in XRD pattern show that identified new phase Cu10Sn3 caused the material properties fragile.

Iodofluorination of Alkenes Using IF5–Pyridine–HF

Iodofluorination of alkenes was performed by using IF5–pyridine–HF and a reductant such as potassium iodide or tin powder. The addition of IF to the double bond proceeded with stereo- and regioselectivity. In the reaction with internal alkenes, the trans-addition product was obtained selectively. With terminal alkenes, the addition took place regioselectively to give 1-iodo-2-fluoroalkanes.

Improvement of electrical properties of through silicon vias metal interconnector by adding single-walled nanotubes

A novel through silicon via (TSV) interconnector, which consists of tin (Sn) powder and single-walled nanotube (SWNT) powder, is proposed and characterized. Most conventional TSV structures, which are commercially available to integrate multiple chips on one packaging, utilize electroplated copper as the interconnector. However, the electroplating-based process has some drawbacks, such as highly demanding fabrication processes in high-aspect-ratio vias, numerous voids, and high cost. To avoid these issues, we used Sn powder mixed with SWNTs as TSV interconnector. SWNTs have been added to improve the electrical properties of TSVs filled only with Sn. The electrical resistance of Sn powder-filled TSVs is 44.59 Ω, but it is markedly decreased to 5 Ω when a Sn and SWNTs mixture (weight ratio of ) was used as the TSV interconnector. In addition, the proposed method could be used for various applications owing to its low process temperature.

Rheological behavior of β-Ti and NiTi powders produced by atomization for SLM production of open porous orthopedic implants

The growing interest for Selective Laser Melting (SLM) in orthopedic implant manufacturing is accompanied by the introduction of novel Ti alloys, in particular β-Ti for their excellent corrosion resistance as well as favorable combination of high mechanical strength, fatigue resistance and relatively low elastic modulus. As part of the SLM process for producing quality β-Ti parts powder flowability is essential to achieve uniform thickness of powder layers. In this work the flowability of different gas atomized β-Ti, including NiTi, powders has been studied. Their rheological properties were compared to those of commercially available plasma-atomized Ti–6Al–4V powder using a newly developed semi-automatic experimental set-up. Not only the particle size, shape and size distribution of the powders display a large influence on the powder flowability but also particle surface properties such as roughness, chemical composition and the presence of liquid on the surface of the particles. It was found that plasma or gas atomization production techniques for SLM powder have a considerable effect on the particle topography. Among the powders studied regarding SLM applicability only rheological properties of the fine size fraction (25–45μm) of Ti–45Nb didn't conform to SLM processing requirements. To improve flowability of the Ti–45Nb powder it was annealed both in air and argon atmosphere at 600°C during 1h, resulting in an improved rheological behavior suitable for SLM processing.

Effect of mechanical milling of elemental powders on interface formation in TiN–Ni cermets prepared by pulsed current sintering

Interfaces of TiN–Ni cermets prepared by mechanical milling (MM) of TiN and Ni powders and the pulsed current sintering (PCS) method were investigated using TEM and high resolution TEM. The MM is an effective method for the formation of the TiN/Ni interface. Coherent TiN/Ni interfaces were observed in the sintered sample. The orientation relationship of the coherent interface was (111)TiN/(111)Ni. This coherent interface was formed by the Ni lattice expansion due to the introduction of the dislocations. Therefore, the Ni energy state in the cermet was metastable. The MM can excite the Ni energy state to a higher state rather than the metastable state in the cermet, and subsequent PCS leads to the Ni metastable state by relaxation of the exited energy; presuming that this process requires the lower activation energy compared with the amount that the Ni energy is excited to the metastable state from the stable (non-milled) state.

Pt-Decorated Fluorine-Doped Tin Oxide Nanowire Arrays As Highly Sensitive H2O2 sensor Electrodes

Fluorine-doped tin oxide (FTO) nanowre aways were grown on top of commercial FTO glass through a vapor-liquid-solid process, by using Au nanocrystals as the anisotropic growth catalyst, tin powders as the precursor, and NH4F as the fluorine source. This extended 3-D FTO nanostructure was then decorated with Pt nanocrystals, with a polyol method, to serve as a sensing electrode for H2O2. These FTO nanowires not only offer greatly enlarged sensing area and fast charge transport channels, but also significantly enhance the hydrophilicity of the electrode, all beneficial for electrochemical sensing of aqueous samples. A two-order of magnitude improvement in sensitivity toward H2O2 over the plain commercial FTO glass was achieved, reaching a high sensitivity value of 272 mA/M.

Effect of starting materials on the wear performance of NiTi-based composites

NiTi alloys have exhibited significant potential as a matrix of wear resistant composites. In this study, in order to examine the effect of starting materials on the wear performance of NiTi-based composites, both elemental Ni/Ti and prealloyed NiTi powders were used to fabricate NiTi–6wt% nano-Al2O3 composites using hot isostatic pressing (HIP). Nanoindentation and microhardness test results indicate that the composite samples produced from the elemental Ni/Ti powders exhibited higher hardness and lower pseudoelasticity properties than those of the samples fabricated from the prealloyed NiTi powders; this is attributed to the higher amount of Ni3Ti/NiTi2 phases in the samples from the elemental powders. The wear test results also confirm the superior performance of the composite samples produced from the elemental powders. The high-resolution transmission electron microscopy studies of the wear debris demonstrate that the heavy local plastic deformation induced during the wear test appeared to inhibit the pseudoelasticity during the wear process. Hence, it can be deduced that the role of the hardness enhancement is more pronounced than that of the pseudoelasticity reduction in the wear performance of NiTi-based composite samples.

Electrical conductivity of copper and tin in the region of a low density and a high specific energy

The electrical conductivities of high-porosity copper and tin samples are measured during shock compression at a low density and a high specific energy of a substance. The dependences of electrical conductivity on the shock pressure are constructed for a copper powder with a density of 0.76 g/cm3 (porosity coefficient of 11.8) and for tin powders with a density of 1.9 and 4.8 g/cm3 (porosity coefficients of 3.9 and 1.5). These dependences are nonmonotonic. At a high pressure, the electrical conductivities of the copper and tin powders weakly depend on the shock pressure. At a pressure p > 2 GPa, the electrical conductivity of the copper powder agrees satisfactorily with the Bakulin model.

Cavitation-resistant NiTi coatings produced by low-pressure plasma spraying (LPPS)

Cavitation is a severe wear mechanism in technical applications where parts are in contact with rapidly flowing liquids. Examples are turbine blades in hydropower plants or pump components. Coating exposed surfaces with wear-resistant materials is an effective measure for extending lifetime in the case of cavitation attack. NiTi is an attractive material for such coatings considering its clearly pronounced damping behavior based on its pseudoelastic properties. A promising processing route for coating net-shaped components with NiTi is low-pressure plasma spraying (LPPS). In the present work, NiTi layers were produced by LPPS, starting from pre-alloyed NiTi powder. Cavitation resistance was investigated in relation to LPPS parameters, layer thickness and specific surface treatment. Increased cavitation resistance was demonstrated compared to UTP 730, an established cavitation protection material. The study was accompanied by comprehensive characterization of microstructure and phase transformation behavior of the NiTi coatings.

Change in Structure During Consolidation of Calcium Hydride Powders of TiNi Intermetallic

Results are provided for a study of the composition, structure, and physicochemical properties of TiNi intermetallic powder prepared by a calcium hydride method. The effect of various forms of consolidation (HIP and hydrostatic compaction followed by vacuum sintering) on the chemical and phase composition of compacts from calcium hydride powders is studied by optical and scanning electron microscopy, x-ray structural analysis, and gas-forming element analysis. A change is shown in the phase composition as a result of TiNi powder consolidation. It is established that vacuum sintering makes it possible to reduce the content of gas-forming admixtures (oxygen, nitrogen, and hydrogen).

Experimental investigations of tin cementation in dispersion form

The results of experimental investigations related to cementation extraction of tin in the dispersion form from sulfate solutions are described. The dependence of stationary aluminum potential on chlorine ion concentration in sulfate solution of divalent tin is shown. The polarization measurements of electrode processes of the Al–Sn galvanic cell have been carried out. The cementation conditions dependence of the dispersivity and bulk density of tin powder is established

Microstructure and Strength of NiTi-Nb Eutectic Braze Joining NiTi Wires

NiTi wires were brazed together via liquid eutectic formation between NiTi and Nb powders deposited at the wire contact region. The brazed region shows proeutectic NiTi(Nb) in contact with the wires, sandwiching a NiTi-Nb eutectic structure, whose microhardness and stiffness, as characterized via nanoindentation, are higher than the NiTi wires, while also showing signs of high ductility. NiTi-Nb eutectic bonding may thus be a viable approach for producing shape-memory NiTi scaffolds brazed from stacked, woven, or braided wires.

NiTi porous structure with 3D interconnected microchannels using steel wire spaceholders

NiTi porous structures with fully 3D interconnected microchannels were created by a powder-metallurgy method using steel wires as spaceholders. Prealloyed NiTi powders were near-fully densified by hot pressing within a high carbon steel wire scaffold, which was then electrochemically dissolved. This resulted in a regular 3D network of orthogonally interconnected microchannels with ellipsoidal cross-sections with 60% volume fraction. The measured elastic stiffness of 14GPa compares well to porous and composite models, as well as finite element modeling despite varying geometry and deformation model assumptions. The structure, which is martensitic at room temperature, exhibits brittle fracture at a relatively low stress of 88MPa due to a TiC interphase at all NiTi powder boundaries. The volume fraction, orientation, shape, and spatial distribution of the microchannels is fully controlled with this method. This makes the structure attractive for biomedical applications, specifically bone implants. The potential shape memory properties achievable through optimized processing would also make the structure effective for energy absorption or actuators.

Influence of TiHX Addition on SHS Porous Shape Memory Alloy

Porous NiTi alloys are receiving considerable attention as they can be used as scaffold for bone replacement. Most production routes presented in the literature use metal powders as raw material (pure Ni and Ti or prealloyed NiTi powders): among these processes, Self propagating High temperature Synthesis (SHS) is investigated as a possible energy saving, quick and easy method of production. To obtain porous NiTi, compacted Ti and Ni powders are preheated and then ignited, avoiding high reaction temperatures at which the compound melts and consequently pores collapse. A drawback of low reaction temperatures is the formation of secondary phases. In this paper the addition of hydrided titanium (TiHX, x=1.5-1.9) powder is considered. During the reaction, hydrided titanium endothermically decomposes and can act as process controlling media. Reference Ni-Ti and Ni-TiHx mixed powders were reacted and the temperature evolution monitored. Differential Scanning Calorimetry was used to verify the presence of transforming phases (austenite, martensite). Microstructure characterization was performed with X-ray diffraction analysis and scanning electron microscope, equipped with EDX and EBSD detectors. The results confirmed that decomposition of hydrided titanium is the controlling process of the reaction, limiting the availability of Ti and absorbing reaction heat. The presence of TiHx can suppress SHS reaction, leaving un-reacted Ni and Ti powders and high amount of other intermetallic phases. If partial or complete decomposition of TiHx is allowed during preheating of reactants, NiTi production can occur: secondary phases content decreases for increased decomposition of TiHx before SHS reaction.

Synthesis of Ethylα-Methylene-γ-amino Carboxylates Promoted by Tin Powder

探索了锡粉促进下,以1,4-二氧六环为溶剂,在室温条件下,通过醛、芳胺和2-溴甲基丙烯酸乙酯的烯丙基化反应,合成α-亚甲基-γ-氨基酸酯的方法.该方法不需使用任何催化剂,具有高效、环境友好、价格低廉和操作简便等特点.