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In fluoride-assisted galvanic replacement reaction (FAGRR), metallic dendrites are formed simultaneously with hydrogen gas. However, the presence of hydrogen bubbles impedes the reduction of metallic ions to form metallic dendrites. This study investigates the FAGRR approach to manufacturing Ag dendrites where ethanol is incorporated into an AgNO3 reaction solution. The findings of this study demonstrate the efficacy of ethanol as an antifoaming agent in enhancing the deposition of the Ag dendrites during the FAGRR process. The antifoaming effect of ethanol becomes more intense at higher concentrations of AgNO3. The introduction of ethanol into FAGRR can significantly improve processing efficiency and yield in the limited time for manufacturing science and engineering. [ABSTRACT FROM AUTHOR]

The fluoride-assisted galvanic replacement reaction is a conventional method for fabricating metallic dendrites on silicon wafers. However, whether bubbles affect manufacturing metallic dendrites is unclear. This study investigated the effects of bubbles on manufacturing Au dendrites and silicon nanowires through metal-assisted chemical etching. The results of manufacture under three conditions (standard, shaking, and vacuum conditions) were compared. Synchronous growth of Au dendrites and silicon nanowires were observed on the silicon wafers. The Au dendrite deposition rate was higher than the silicon etching rate. Compared with the standard condition, the vacuum condition increased the synthesis rates of Au dendrites and silicon nanowires by 1.1 and 0.2 µm/min, respectively. Therefore, the elimination of bubbles by vacuum can considerably accelerate manufacturing Au dendrites and silicon nanowires. [ABSTRACT FROM AUTHOR]

Micro/nano-textured Si wafers manufactured using metal-assisted chemical etching (MACE) have been the focus of several studies, but the mechanism of bubble generation during the MACE process affecting textured surfaces has rarely been reported. This study investigated the bubble effect due to the different placement patterns of the Si wafer (face-up, stirred face-down, and face-down). The results indicated that the placement pattern of the Si wafer notably influences the uniformity of outward appearance. At 2 h of etching, the outward appearance uniformity of face-up etching was more homogeneous than that of stirred face-down and face-down patterns, and the Si nanowires (SiNWs) processed through face-up etching were longer (41 μm) than those subjected to stirred face-down etching (36 μm) and face-down etching (32 μm). Therefore, the placement pattern of Si wafer can affect the uniformity and properties of SiNWs because of bubbles trapped inside cavities or between SiNWs. [ABSTRACT FROM AUTHOR]

In the present study, amorphous Ni60Nb20Zr20 and Ti50Cu28Ni15Sn7 alloy powders were synthesized separately using a mechanical alloying (MA) technique. The dual-amorphous-phased (Ti50Cu28Ni15Sn7)100− x (Ni60Nb20Zr20) x ( x = 0, 10, 20, and 30 vol%) powders were prepared by mixing the corresponding amorphous powders. The dual-amorphous-phased powders were then consolidated into bulk amorphous/amorphous composite (BA/AC) alloy discs. The amorphization status of as-prepared powders and bulk BA/AC composite discs was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The microstructure of the BA/AC discs showed that the Ni60Nb20Zr20 phase is distributed homogeneously within the Ti50Cu28Ni15Sn7 matrix. The (Ti50Cu28Ni15Sn7)70(Ni60Nb20Zr20)30 BA/AC disc exhibited a relative density of 96.6% and its Vickers microhardness was 726 kg/mm2. [ABSTRACT FROM AUTHOR]

In this study, γ-Al2O3 particles were dispersed in p-type Bi0.4Sb1.6Te3 through mechanical alloying to form γ-Al2O3/Bi0.4Sb1.6Te3 composite powders. The composite powders were consolidated using vacuum hot pressing to produce nano- and microstructured composites. Thermoelectric (TE) measurements indicated that adding an optimal amount of γ-Al2O3 nanoparticles improves the TE performance of the fabricated composites. High TE performances with figure of merit (ZT) values as high as 1.22 and 1.21 were achieved at 373 and 398 K for samples containing 1 and 3 wt % γ-Al2O3 nanoparticles, respectively. These ZT values are higher than those of monolithic Bi0.4Sb1.6Te3 samples. The ZT values of the fabricated samples at 298-423 K are 1.0-1.22; these ZT characteristics make γ-Al2O3/Bi0.4Sb1.6Te3 composites suitable for power generation applications because no other material with a similarly high ZT value has been reported at this temperature range. The achieved high ZT value may be attributable to the unique nano- and microstructures in which γ-Al2O3 nanoparticles are dispersed among the grain boundary or in the matrix grain, as revealed by high-resolution transmission electron microscopy. The dispersed γ-Al2O3 nanoparticles thus increase phonon scattering sites and reduce thermal conductivity. The results indicated that the nano- and microstructured γ-Al2O3/Bi0.4Sb1.6Te3 alloy can serve as a high-performance material for application in TE devices. [ABSTRACT FROM AUTHOR]