Interfacial reaction between Ni particle reinforcements and liquid Sn-based eutectic solders

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chung-Yung Lin
Keyword(s):  
Growth Kinetics ◽  
Composite Solder ◽  
Solder Matrix ◽  
Alloying Elements ◽  
Alloying Element ◽  
Content Type ◽  
Flat Substrate ◽  
Diffusion Controlled ◽  
Kinetics Of ◽  
Rate Controlling Step

Purpose This paper aims to derive a model of growth kinetics of the intermetallic compound (IMC) layer formed in the reaction between liquid Sn-based solders and Ni particle reinforcements and to compare with the experimental data to verify the effects of Sn concentration and alloying element. Design/methodology/approach A composite solder was manufactured by mechanically introducing Ni particle reinforcements into a solder matrix. The effect of the non-reactive alloying elements, Ag, Pb and Bi, on the growth kinetics of the IMC formed between liquid Sn-based eutectic solders and Ni particles, reacting this composite solder at 250°C–280°C was studied. Findings Experimental results showed that only the IMC Ni3Sn4 was present as a reaction product. Using the diffusion-controlled reaction mechanism, a kinetic equation quantifying both Sn concentration and alloying element effects was derived and verified by comparing the kinetic data obtained using four different solders with different concentrations of Sn and the alloying elements. Originality/value The similarity between the activation energies of these four solders confirms that the diffusion of Sn atoms through the IMC is the rate-controlling step. Besides, the kinetic values are independent of the geometry of Ni, whether spherical particle or flat substrate.

Impact of pH on growth of Staphylococcus epidermidis and Staphylococcus aureus in vitro

2021 ◽  
Vol 70 (9) ◽  
Author(s):  
Vidula Iyer ◽  
Janhavi Raut ◽  
Anindya Dasgupta
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Kinetics ◽  
Staphylococcus Epidermidis ◽  
Type Species ◽  
Ph Dependence ◽  
Skin Microbiome ◽  
Content Type ◽  
Link Type ◽  
Kinetics Of

The pH of skin is critical for skin health and resilience and plays a key role in controlling the skin microbiome. It has been well reported that under dysbiotic conditions such as atopic dermatitis (AD), eczema, etc. there are significant aberrations of skin pH, along with a higher level of Staphylococcus aureus compared to the commensal Staphylococcus epidermidis on skin. To understand the effect of pH on the relative growth of S. epidermidis and S. aureus , we carried out simple in vitro growth kinetic studies of the individual microbes under varying pH conditions. We demonstrated that the growth kinetics of S. epidermidis is relatively insensitive to pH within the range of 5–7, while S. aureus shows a stronger pH dependence in that range. Gompertz’s model was used to fit the pH dependence of the growth kinetics of the two bacteria and showed that the equilibrium bacterial count of S. aureus was the more sensitive parameter. The switch in growth rate happens at a pH of 6.5–7. Our studies are in line with the general hypothesis that keeping the skin pH within an acidic range is advantageous in terms of keeping the skin microbiome in balance and maintaining healthy skin.

Measurement of Growth Kinetics of Deeply Undercooled Zr50Cu50 Melt by Electromagnetic Levitation Technique

2014 ◽  
Vol 513-517 ◽  
pp. 56-59
Author(s):  
Li Xin Li ◽  
Jun Liang Zhao ◽  
Xue Mao Guan
Keyword(s):  
Crystal Growth ◽  
Growth Kinetics ◽  
Electromagnetic Levitation ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Diffusion Controlled ◽  
Crystal Growth Mechanism ◽  
Crystal Growth Kinetics ◽  
First Time ◽  
Kinetics Of

The crystal growth kinetics in the deeply undercooled Zr50Cu50 melt was studied with the electromagnetic levitation technique. The maximum growth rate umax was, for the first time, demonstrated in undercooled metal and alloy melts, and this allowed us to construct the complete profile of crystal growth kinetics in the whole undercooling region of Zr50Cu50 melt. In deep undercooling region near glass transition, the diffusion-controlled crystal growth mechanism accounted for the growth kinetics, while at lower undercooling the profile around umax remarkably differed from what the classical growth theory covers.

Microstructures evolution and growth kinetics of intermetallic compounds in Cu/Sn/Cu system during ultrasonic soldering process

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xu Han ◽  
Xiaoyan Li ◽  
Peng Yao
Keyword(s):  
Grain Boundary ◽  
Microstructural Evolution ◽  
Growth Kinetics ◽  
Boundary Diffusion ◽  
Solder Joints ◽  
Content Type ◽  
Soldering Process ◽  
Different Temperatures ◽  
Ultrasonic Soldering ◽  
Kinetics Of

Purpose This study aims to investigate the effect of ultrasound on interfacial microstructures and growth kinetics of intermetallic compounds (IMCs) at different temperatures. Design/methodology/approach To investigate the effect of ultrasound on IMCs growth quantitatively, the cross-sectional area of IMCs layers over a confirmed length was obtained for calculating the thickness of the IMCs layer. Findings The generation of dimensional difference in normal direction between Cu6Sn5 and its adjacent Cu6Sn5, formation of bossed Cu6Sn5 and non-interfacial Cu6Sn5 in ultrasonic solder joints made the interfacial Cu6Sn5 layer present a non-scallop-like morphology different from that of traditional solder joints. At 260°C and 290°C, the Cu3Sn layer presented a wave-like shape. In contrast, at 320°C, the Cu3Sn in ultrasonic solder joints consisted of non-interfacial Cu3Sn and interfacial Cu3Sn with a branch-like shape. The Cu6Sn5/Cu3Sn boundary and Cu3Sn/Cu interface presented a sawtooth-like shape under the effect of ultrasound. The predominant mechanism of ultrasonic-assisted growth of Cu6Sn5 growth at 260°C, 290°C and 320°C involved the grain boundary diffusion accompanied by grain coarsening. The Cu3Sn growth was controlled by volume diffusion during the ultrasonic soldering process at 260°C and 290°C. The diffusion mechanism of Cu3Sn growth transformed to grain boundary diffusion accompanied by grain coarsening when the ultrasonic soldering temperature was increased to 320°C. Originality/value The microstructural evolution and growth kinetics of IMCs in ultrasonically prepared ultrasonic solder joints at different temperatures have rarely been reported in previous studies. In this study, the effect of ultrasound on microstructural evolution and growth kinetics of IMCs was systematically investigated.

Diffusion Controlled Abnormal Grain Growth in Ceramics

2007 ◽  
Vol 558-559 ◽  
pp. 1227-1236 ◽  
Author(s):  
Shen J. Dillon ◽  
Martin P. Harmer
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Abnormal Grain Growth ◽  
Growth Theory ◽  
Diffusion Controlled ◽  
Grain Growth Kinetics ◽  
Kinetics Of

The grain growth kinetics of silica and calcia doped alumina at 1400oC and their grain boundary complexion is characterized. These data are compared to predictions of both diffusion controlled and nucleation limited interface controlled grain growth theory. It is deduced from the indicators that the mechanism for normal and abnormal grain growth in these aluminas is diffusion controlled.

Phase Decomposition in Isothermally Aged MA Cu-Ni-Fe and Cu-Ni-Cr Alloys

2006 ◽  
Vol 15-17 ◽  
pp. 678-683 ◽  
Author(s):  
Felipe Hernandez-Santiago ◽  
I. Espinoza-Ramirez ◽  
Victor M. Lopez-Hirata ◽  
Maribel L. Saucedo-Muñoz ◽  
Lucia Díaz-Barriga Arceo ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Growth Kinetics ◽  
Phase Decomposition ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Composition Modulation ◽  
Diffusion Controlled ◽  
Supersaturated Solid Solutions ◽  
Kinetics Of ◽  
Modulation Wavelength

Supersaturated solid solutions of Cu-44.5at.%Ni-22.5at.%Fe and Cu-37at.%Ni-6at.%Cr alloy were produced by ball milling of a pure chemical elemental mixture for 1080 ks. Two fcc supersaturated solid solutions with a grain size of about 20 and 50 nm, respectively, were obtained after milling. These alloys were subsequently aged at temperatures between 800 and 1003 K for different times. The aging promoted the phase decomposition of the supersaturated solid solution into a mixture of Cu-rich and Ni- phases in both the aged MA alloy powders. The growth kinetics of the modulation wavelength was determined from the X-ray diffraction results and followed the Lifshitz-Slyozov- Wagner theory for a diffusion-controlled coarsening in the mechanically-alloyed Cu-Ni-Fe alloy after aging. However, the sidebands intensity seems to be very low and overlapped with the peaks corresponding to the Cu-rich phase in the aged mechanically-alloyed Cu-Ni-Cr alloy. The growth kinetics of composition modulation wavelength for the aged MA Cu-Ni-Fe alloy was faster at 803 and 898 K than that for the same alloy composition obtained by a conventional processing and then aged at the same temperatures.

scholarly journals Temperature-Dependent Growth Modeling of Environmental and Clinical Legionella pneumophila Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes

2017 ◽  
Vol 83 (8) ◽  
Author(s):  
Yehonatan Sharaby ◽  
Sarah Rodríguez-Martínez ◽  
Olga Oks ◽  
Marina Pecellin ◽  
Hila Mizrahi ◽  
...  
Keyword(s):  
Drinking Water ◽  
Growth Kinetics ◽  
Legionella Pneumophila ◽  
Variable Number Tandem Repeat ◽  
Ecological Niches ◽  
Water Network ◽  
Temperature Dependent ◽  
Content Type ◽  
Dependent Growth ◽  
Kinetics Of

ABSTRACT Legionella pneumophila causes waterborne infections resulting in severe pneumonia. High-resolution genotyping of L. pneumophila isolates can be achieved by multiple-locus variable-number tandem-repeat analysis (MLVA). Recently, we found that different MLVA genotypes of L. pneumophila dominated different sites in a small drinking-water network, with a genotype-related temperature and abundance regime. The present study focuses on understanding the temperature-dependent growth kinetics of the genotypes that dominated the water network. Our aim was to model mathematically the influence of temperature on the growth kinetics of different environmental and clinical L. pneumophila genotypes and to compare it with the influence of their ecological niches. Environmental strains showed a distinct temperature preference, with significant differences among the growth kinetics of the three studied genotypes (Gt4, Gt6, and Gt15). Gt4 strains exhibited superior growth at lower temperatures (25 and 30°C), while Gt15 strains appeared to be best adapted to relatively higher temperatures (42 and 45°C). The temperature-dependent growth traits of the environmental genotypes were consistent with their distribution and temperature preferences in the water network. Clinical isolates exhibited significantly higher growth rates and reached higher maximal cell densities at 37°C and 42°C than the environmental strains. Further research on the growth preferences of L. pneumophila clinical and environmental genotypes will result in a better understanding of their ecological niches in drinking-water systems as well as in the human body. IMPORTANCE Legionella pneumophila is a waterborne pathogen that threatens humans in developed countries. The bacteria inhabit natural and man-made freshwater environments. Here we demonstrate that different environmental L. pneumophila genotypes have different temperature-dependent growth kinetics. Moreover, Legionella strains that belong to the same species but were isolated from environmental and clinical sources possess adaptations for growth at different temperatures. These growth preferences may influence the bacterial colonization at specific ecological niches within the drinking-water network. Adaptations for growth at human body temperatures may facilitate the abilities of some L. pneumophila strains to infect and cause illness in humans. Our findings may be used as a tool to improve Legionella monitoring in drinking-water networks. Risk assessment models for predicting the risk of legionellosis should take into account not only Legionella concentrations but also the temperature-dependent growth kinetics of the isolates.

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