New local joining technique for metal materials using exothermic heat of Al/Ni multilayer powder

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This paper focuses on developing Ti-SiO x nanoparticles and evaluating their self-propagating exothermic function. In combination with an atomized heating method, molten salt reduction, and sputtering, we established a fabrication technique for Ti-SiO x nanoparticles in which their exothermic characteristics can be designed. In the atomized heating method, porous SiO x nanoparticles with various spherical shapes, sizes, and porosities were fabricated. Porous SiO x nanoparticles with uniformly arranged pores were produced at a polystyrene latex (PSL) concentration of approximately 3.0 wt%. Reduction of the oxygen content of the porous SiO x nanoparticles was conducted using molten salt. Ti was deposited onto the entire surface by stirring and sputtering. The completed 1.0 mg of Ti-SiO x nanoparticle powder exhibited a self-propagating exothermic reaction by applying an electric spark. The relationship between PSL concentration and heat generation characteristics, such as the maximum temperature, time to reach maximum temperature, and duration of the exothermic reaction, was investigated.

Section: Exothermic Performance Test Of Titanium-silica Nanoparticlesmentioning

confidence: 99%

Exothermically reactive titanium–silica nanoparticles

Shindo

Kiyohara

Inoue

et al. 2020

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“…In our study, to improve the productivity and convenience of the heat source, an Al/Ni multilayer powder fabricated by the coldrolling and frictional pulverizing methods was developed, and the thermal reaction characteristics were studied. 13,[25][26][27][28] In a previous study, we revealed that the exothermic reaction characteristics, such as the reaction speed and maximum exothermic reaction temperature, increase with an increase in the number of cold-rolling passes. 25) These characteristics can be controlled to some extent by changing the rolling conditions.…”

Section: Introductionmentioning

confidence: 99%

Microscale thermal characteristics of cold-rolled aluminum alloy using a thermoreflectance method

Yamashita

Miyake

2022

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In this study, the microscale thermal propagation behavior of cold-rolled aluminum alloy sheets was characterized using a thermoreflectance (TR) method from the micro and macro perspectives, and the relationship between the crystallite sizes of cold-rolled aluminum sheets with different rolling reduction rates and their thermal propagation characteristics was described. The crystallite sizes were analyzed by X-ray diffraction using Scherrer’s equation. The microscale thermal propagation characteristics of these specimens were measured using a TR method with a high spatial resolution of several micrometers through a focused laser beam and by controlling the thermal diffusion length. The macroscale thermal propagation characteristics of these specimens were then measured using two methods: the spot periodic heating method and the electrical resistance measurement method with the Wiedemann–Franz law. Experimental results showed that the microscale thermal propagation correlated with a change in the crystallite size. However, the macroscale thermal conductivity decreased with an increase in the rolling reduction rate regardless of the crystallite size. It is expected that the thermal propagation characteristics at the microscale can be controlled by a change in the crystallite size.

“…The exothermic characteristics of Al/Ni multilayer powders have also been examined. [26][27][28] It was found that such characteristics (e.g. maximum temperature, reaction rate, and intermetallic compound production) can be controlled by changing the number of rolling passes.…”

Section: Introductionmentioning

confidence: 99%

Crystallite size analysis of Al/Ni multilayer powder by synchrotron radiation X-ray diffraction

Yamashita¹,

Yamamoto²,

Miyake³

2021

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The self-propagated exothermic reaction characteristics of Al/Ni multilayer powders can be employed as heat sources and controlled by cold-rolling conditions. This feature depends on the heat propagation inside of crystal grains. Therefore, the crystallographic factor that relates cold-rolling conditions to exothermic characteristics should be identified. To determine the change trend in crystallite size with the increase in the number of rolling passes, the crystallite sizes in the Al/Ni multilayer powder were calculated using Scherrer’s equation, and precise X-ray profiles were obtained using the synchrotron radiation X-ray diffraction method. The results indicate that the crystallite sizes were refined by increasing the number of rolling passes up to 30; from 30 to 40 passes, however, the crystallite sizes increased. It is assumed that, in addition to the Al/Ni multilayer powder being thin and multilayered, the increase in crystallite size at 40 passes allows for the smooth propagation of heat, consequently improving the exothermic characteristics. Therefore, crystallite size is the dominant parameter in the relationship between rolling conditions and exothermic characteristics.