Papers by Keyword: Ni

Abstract: Ceramic Metallic Alloys of TiC/Ni, Comprising Titanium Carbide with Nickel Contents of 5%, 15%, 30%, and 50%, were Fabricated through Solid-Phase Sintering at 1400°C with a 2-hour Holding Time and a Pressure of 50MPa. This Study Explores the Impact of Nickel Content on the Mechanical and Structural Properties. The Solidification Mechanism between TiC and Ni is Governed by Carbon Diffusion through TiC Particles, Affecting the Morphology of TiC and Carbon Particles in Ni Samples. The Reaction Behavior within the TiC/Ni Alloys was Analyzed, and Microstructural and Mechanical Characteristics were Examined to Evaluate the Influence of Varying Nickel Contents. Results indicate that in all samples, the TiC matrix exhibited a solid solution of the FCC phase. The reaction mechanism of Ti-C-Ni reveals the evolution of solid phase formation with increasing nickel content. As nickel content increases, the mass and size of nickel particles grow, leading to a more uniform and homogeneous structure. At a nickel content of 15%, the samples displayed a bending strength of 1200 ± 50 N, a microhardness of 800 ± 20 (HV _0.1), and a density of 5.6 ± 0.2.

Abstract: Ni-cellulose nanofiber (CNF) composite plated films were fabricated by electroless plating method. The deposition conditions and basic properties of the Ni-CNF composite film were investigated. A C1100 plate was used as the plated material, and a Ni-P electroless plating bath was prepared as the plating solution. 5 g/L of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidized CNF or carboxymethyl cellulose was added to the plating solution. Sodium dodecyl sulfate (SDS) was added as a surfactant. It was confirmed that CNFs were complexed on the surface of the plated film, and the addition of SDS made CNFs disperse into the plated film. The surface of the plated film obtained by adding both TEMPO oxidized CNF and SDS had the highest Vickers hardness among all conditions investigated.

Abstract: This study offers a comprehensive examination of the behavior of 3C-SiC crystals grown on 4° off-axis (100) Si substrates with different off-axis angles along <110> and <100> for N and Al doping, respectively. The investigation takes advantage of molten KOH etching to conduct an in-depth investigation of the average density and size of the SFs inside the crystal for both n- and p-type doped 3C-SiC epitaxial layers. Moreover, 3C-SiC grown on a <100> off-cut substrate was revealed to have a greater concentration of SFs due to the absence of self-annihilation along the plane (-1-10). Considering two different doping ranges suitable for IGBTs and MOSFETs development, the impact of doping and off-angle on the crystal quality, concentration, and length distribution of SFs was then investigated in order to quantify the influence of N and Al incorporation on the structural and optical characteristics of the semiconductor. It turned out that under heavy nitrogen doping (~10¹⁹ cm^-3), when the dopant concentration grew, the average length of the stacking faults (SFs) expanded while their density dropped.

Abstract: The preparation of ohmic contact with high stability and low resistance is critical, and the quality of ohmic contact will directly affect the performance of devices as the efficiency, gain and switching speed. In this work, the I-V characteristic of the 4H-SiC devices under rapid thermal annealing and pulsed laser annealing were compared, the pulsed laser annealing process could obtain the lower ohmic contact resistant. The surface morphology, material composition, and elemental analysis were clarified by optical microscopy (OM), X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS), respectively. This research suggests that more Ni₂Si and carbon vacancy can form at the interface under pulsed laser annealing.

Abstract: In this work, we have developed a series of amorphous alloy ribbons of Fe₇₅Co₄B₁₃Y₄Nb_4-xNi_x(x=0, 0.5, 1, 2, 3 and 4) which were prepared by industrial purity alloy. Besides, the effects of Ni substitution and isothermal annealing on the saturation magnetization (M_s) and intrinsic coercive force (jH_c) were systematically investigated. The SQUID-VSM data pointed out the M_s has been increased by Ni content addition with largest enhanced by 57 % from 114 emu/g to 180 emu/g. After quickly annealing at the optimal temperature, the M_s reached 199 emu/g and jH_c decreased from 50 Oe to 33 Oe. DSC measurements displayed that this system has a multi-step crystallization in the heating process. Under the premise of maintaining the excellent amorphous forming ability (AFA), the gap between the two crystallization peaks was broadened with Ni addition, which is good to the forming of α-Fe phase at the annealing treatment. And this was also consistent with the X-ray diffractometer (XRD) results. The Scherrer formula calculated results suggested that isothermal annealing has significant effect on size of α-Fe nanocrystals in annealing process, which obvious affect the M_s and jH_c. The annealing temperature and time can not only affect the precipitation of nano-crystalline, but also control the grain size. Hence, an appropriate annealing process is very important to improve the properties of these iron-based nanocrystalline magnetic materials. In conclusion, the results will help us to understand the influence of Ni elements and isothermal annealing on the microstructure and magnetic of Fe₇₅Co₄B₁₃Y₄Nb_4-xNi_x amorphous alloys.

Abstract: We report on time-dependent Positron annihilation induced Auger Electron Spectroscopy (PAES) study on 0.5 monolayers (ML) Ni on polycrystalline Pd accompanied by complementary X-ray induced Photoelectron Spectroscopy (XPS). The normalized PAES spectra showed a significant decrease in the Ni intensity and an increase in the Pd intensity as a function of time. To rule out varying influence on the elements e.g. from surface contaminates due to the residual gas, a time-dependent XPS analysis was performed on pure Ni and Pd as well as to analyze the main contaminants C and O. The O fraction was found to be constant within the measurement time and the time constants for C significantly differ from those of Ni and Pd in the PAES data. Consequently, it was concluded that the PAES data show a superposition of C contamination and structural changes at the surface of Ni/Pd.

Abstract: The aims of present study were investigated the effect of nickel doping on the dielectric and piezoelectric properties of P(BN)ZT solid solution. P(BN)ZT powder doped with nickel nanoparticle in the composition of (1-x) PBNZT–xNi when x = 0, 2, 4, 6, 8 and 10 percent by mole. P(BN)ZT doped with nickel powder were calcined at 900 °C for 2 h and sintered at the temperature range of 1150 -1250°C for 2 h with heating/cooling rate of 5 °C/min. The dielectric constant (e_r) and the dielectric loss tangent (tand) of all ceramics were measured at room temperature using LCR meter. The piezoelectric properties (d₃₃) were measured at room temperature using d₃₃ meter. The micro and nano-domain structure was clearly observed by piezo-response force microscopy (PFM). From the results, it can be seen that the dielectric and piezoelectric decreased with increasing Ni particle of all composition (0.0-0.1 mol%). Moreover, PFM images show that the micro (180°) and nano (90°) domain are orientated at the surface region in submicron-scale of P(BN)ZT ceramics with doped nickel nanoparticle.

Abstract: Electroless Ni deposition is often used in presence of Cu, Ti and Au. Recently TiW has also started to be employed, but with this alloy the Ni deposition is not always neat. In our work we investigate the effect of different wet treatments on the Ni growth by means of XPS analyses and SEM inspections. It is found that an oxidized surface inhibits the activator deposition. The de-oxidized Ti atoms in TiW on the other hand are believed to act as the principal sites for Pd seed deposition and subsequent Ni growth.

Abstract: Ni/Al₂O₃ nanocomposites have a crack healing function which results in recovery of mechanical strength. The function is caused by oxidations of Ni particles within matrix. Oxidation of Ni dispersion also results in the evolution of oxidized zone, which consists of NiAl₂O₄ grains in Al₂O₃ matrix. Degradations by high-temperature oxidation before introduction of surface crack is necessary to investigate for estimating the life time of the present material system. Samples of Ni/Al₂O₃ nanocomposites were prepared by using pulsed electric current sintering and pre-oxidized at 1200°C for 1-6 d in air. Surface cracks were given by the Vickers indentation at 49 N for 10 s. The samples were oxidized again at 1200°C for 6 h in air to heal the surface cracks. Longer pre-oxidation time of samples results in degradation of the performance of surface crack disappearance. Bending strength of healed samples with 2 d pre-oxidation was comparable with the samples before cracks introduction. After oxidation at 1200°C for 6 h in air, the partially disappearance of cracks was observed on 6 d pre-oxidized samples. Hence, the recovery of bending strength depends on thickness of oxidized zone and depth of surface cracks.

Abstract: In the present study, the effect of addition of Ni nanoparticles on the growth of the intermetallic compound (IMC) layer between low-silver lead-free solder and Cu substrate was investigated. Ni nanoparticles were synthesized and smelted with pure Sn, Ag to prepare Sn-1.0Ag-xNi (x=0, 0.05, 0.1, 0.2) solder alloy. Sn-1.0Ag-xNi was soldered on a copper substrate, and then the solder/Cu couples were isothermally aged at 423K for 360h.The Cross-section images of IMCs layer were obtained to observe the morphology of IMC and to measure the thickness of Cu₆Sn₅ and Cu₃Sn layers respectively. The results show that, during aging, addition of Ni can remarkably improve the morphology of IMC, level the scalloped IMC, facilitate the growth of the total interfacial IMCs and inhibit the growth of Cu₃Sn. Moreover, the rate change of thickness of the Cu₃Sn reduced obviously with the increase of Ni nanoparticles. Comprehensive analysis shows that the addition of Ni promotes the nucleation and growth of Cu₆Sn₅. The thermodynamics calculation on the solder alloy was identical with the experiment result.