Intrinsic Diffusivities Ratio Analysis in Double Multiphase Systems

Our investigations show that electrochemical corrosion of copper is faster than electrochemical corrosion of aluminium at temperatures below 100°C. Literature data analysis shows that the Al atoms diffuse faster than the Cu atoms at temperatures higher than 475°C, Al rich intermetallic compounds (IMCs) are formed faster in the Cu-Al system, and the Kirkendall plane shifts toward the Al side. Electrochemical corrosion occurs due to electric current and due to diffusion. An electronic devise working time, for example, depends on initial copper cover thickness on aluminium wire, connected to the electronic devise, temperature, and volume and dislocation pipe diffusion coefficients, so copper, iron, and aluminium electrochemical corrosion rates are investigated experimentally at room temperature and at temperature 100°C. Intrinsic diffusivities ratios of copper and aluminium at different temperatures and diffusion activation energies in the Cu-Al system are calculated by proposed here methods using literature experimental data. Dislocation pipe and volume diffusion activation energies of pure iron are calculated separately by earlier proposed method using literature experimental data. Aluminium dissolved into NaCl solution as the Al3+ ions at room temperature and at temperature 100°C, iron dissolved into NaCl solution as the Fe2+ (not Fe3+) ions at room temperature and at temperature 100°C, copper dissolved into NaCl solution as the Cu+ ions at room temperature and as the Cu+ and the Cu2+ ions at temperature 100°C. It is found experimentally that copper corrosion is higher than aluminium corrosion, and ratio of electrochemical corrosion rates, kCu/kAl>1, decreases with temperature increasing, although iron electrochemical corrosion rate does not depend on temperature below 100°C. It is obvious, because the melting point of iron is more higher than the melting point of copper or aluminium. It is calculated that the copper electrochemical corrosion rate is approximately equal to aluminium electrochemical corrosion at temperature about 300°C, so copper can dissolve into NaCl solution mostly as the Cu2+ ions at temperature about 300°C. The ratio of intrinsic diffusivities, DCu/DAl<1, increases with temperature increasing, and the intrinsic diffusivity of aluminium could be approximately equal to the intrinsic diffusivity of copper at temperature about 460oC. Intrinsic diffusivities ratios in the Cu-Zn system at temperature 400°C and in the Cu-Sn system at temperatures from 190°C to 250°C are analyzed theoretically using literature experimental data. Diffusion activation energies and pre-exponential coefficients for the Cu-Sn system are calculated combining literature experimental results.

Copper, Iron, and Aluminium Electrochemical Corrosion Rate Dependence on Temperature

Our investigations show that electrochemical corrosion of copper is faster than electrochemical corrosion of aluminium at temperatures below 100°C. Literature data analysis shows that the Al atoms diffuse faster than the Cu atoms at temperatures higher than 475°C, Al-rich intermetallic compounds (IMCs) are formed faster in the Cu-Al system, and the Kirkendall plane shifts towards the Al side. Electrochemical corrosion occurs due to electric current and diffusion. An electronic device working time, for example, depends on the initial copper cover thickness on the aluminium wire, connected to the electronic device, temperature, and volume and dislocation pipe diffusion coefficients, so copper, iron, and aluminium electrochemical corrosion rates are investigated experimentally at room temperature and at temperature 100°C. Intrinsic diffusivities ratios of copper and aluminium at different temperatures and diffusion activation energies in the Cu-Al system are calculated by the proposed methods here using literature experimental data. Dislocation pipe and volume diffusion activation energies of pure iron are calculated separately by earlier proposed methods using literature experimental data. Aluminium dissolved into NaCl solution as the Al3+ ions at room temperature and at temperature 100°C, iron dissolved into NaCl solution as the Fe2+ (not Fe3+) ions at room temperature and at temperature 100°C, copper dissolved into NaCl solution as the Cu+ ions at room temperature, and as the Cu+ and the Cu2+ ions at temperature 100°C. It is found experimentally that copper corrosion is higher than aluminium corrosion, and the ratio of electrochemical corrosion rates, kCu/kAl > 1, decreases with temperature increasing, although iron electrochemical corrosion rate does not depend on temperature below 100°C. It is obvious because the melting point of iron is higher than the melting point of copper or aluminium. It is calculated that copper electrochemical corrosion rate is approximately equal to aluminium electrochemical corrosion at a temperature of about 300°C, so the copper can dissolve into NaCl solution mostly as the Cu2+ ions at a temperature of about 300°C. The ratio of intrinsic diffusivities, DCu/DAl < 1, increases with temperature increasing, and intrinsic diffusivity of aluminium could be approximately equal to intrinsic diffusivity of copper at a temperature of about 460°C.

Copper, Iron, and Aluminium Electrochemical Corrosion Rates and Intrinsic Diffusivitives Dependence on Temperature Investigations

Our investigations show that electrochemical corrosion of copper is faster than electrochemical corrosion of aluminium at temperatures below 100oC. Literature data analysis shows that the Al atoms diffuse faster than the Cu atoms at temperatures higher than 475oC, Al rich intermetallic compounds (IMCs) are formed faster in the Cu-Al system, and the Kirkendall plane shifts toward Al side. Electrochemical corrosion occurs due to electric current and due to diffusion. An electronic devise working time, for example, depends on initial copper cover thickness on aluminium wire, connected to the electronic devise, temperature, and volume and dislocation pipe diffusion coefficients, so copper, iron, and aluminium electrochemical corrosion rates are investigated experimentally at room temperature and at temperature 100oC. Intrinsic diffusivities ratios of copper and aluminium at different temperatures and diffusion activation energies in the Cu-Al system are calculated by proposed here methods using literature experimental data. Dislocation pipe and volume diffusion activation energies of pure iron are calculated separately by earlier proposed method using literature experimental data. Aluminium dissolved into NaCl solution as the Al3+ ions at room temperature and at temperature 100oC, iron dissolved into NaCl solution as the Fe2+ (not Fe3+) ions at room temperature and at temperature 100oC, copper dissolved into NaCl solution as the Cu+ ions at room temperature and as the Cu+ and the Cu2+ ions at temperature 100oC. It is founded experimentally that copper corrosion is higher than aluminium corrosion, and ratio of electrochemical corrosion rates, kCu/kAl&gt;1, decreases with temperature increasing, although iron electrochemical corrosion rate doesn’t depend on temperature below 100oC. It is obvious, because melting point of iron is more higher then melting point of copper or aluminium. It is calculated that copper electrochemical corrosion rate is approximately equal to aluminium electrochemical corrosion at temperature about 300oC, so copper can dissolve into NaCl solution mostly as the Cu2+ ions at temperature about 300oC. Ratio of intrinsic diffusivities, DCu/DAl &lt;1, increases with temperature increasing, and intrinsic diffusivity of aluminium could be approximately equal to intrinsic diffusivity of copper at temperature about 460oC.

Diffusion of oxygen in hypostoichiometric uranium dioxide nanocrystals. A molecular dynamics simulation

A molecular dynamic simulation of diffusion of intrinsic oxygen anions in the bulk of hypostoichiometric UO2-x nanocrystals with a free surface was carried out. The main diffusion mechanism turned out to be the migration of oxygen by the anionic vacancies. It is shown that in the range of values of the non-stoichiometry parameter 0.05 £x £ 0.275 the oxygen diffusion coefficient D is weakly dependent on temperature, despite the uniform distribution of the vacancies over the model crystallite. The reliable D values calculated for the temperature T = 923 K are in the range from 3×10-9 to 7×10-8 cm2/s, in quantitative agreement with the experimental data. The corresponding diffusion activation energy is in the range from 0.57 eV to 0.65 eV, depending on the interaction potentials used for the calculations.

Intermetallics Disappearance Rate Analysis in Double Multiphase Systems

Electric corrosion of aluminium and copper is investigated experimentally. It is found that the electric corrosion of copper is higher than the electric corrosion of aluminium. It is also clarified that the intrinsic diffusion coefficient of Cu is higher than the intrinsic diffusion coefficient of Al in each phase, so inert markers move to Cu. Copper has a higher electric conductivity, higher thermal conduction, and lower material cost than gold, so it is possible to use Cu instead of Au for wire bonding in microelectronics packaging, because the thin Al pad (1.2 μm thickness) can prevent gold and copper corrosion. Intermetallics disappearance and Kirkendall shift rates calculation methods are proposed. Methods involve mass conservation law and concentration profiles change during mutual diffusion. Intermetallics disappearance and Kirkendall shift rates in Al-Cu (Al is thin layer on Cu), Cu-Al (Cu is thin layer on Al), Al-Au, Zn-Cu, and Cu-Sn systems are analyzed theoretically using literature experimental data. Diffusion activation energies and pre-exponential coefficients for Cu-Sn system were calculated combining literature experimental results.

Determination of Drying Characteristics, Energy Consumption and Quality Values of Black Mulberry Fruit (Morus nigra L.) Dried Under Different Conditions

There are about 68 types of mulberry fruit with a wide ecological production area. Different mulberry species are grown in large fields in Turkey. Mulberries are largely dried-consumed, but sometimes they are used as fruit juice. In this study, black mulberry fruit was collected in two different ripening levels (semi-ripe and full-ripe) and oven-dried at 50, 60 and 70°C drying temperatures. Initial moisture contents of semi-ripe and full-ripe fruits were determined as 86.74% and 82.95%, respectively. Fruits were dried to have final moisture levels of 10-15%. Drying duration, drying models, effective diffusion, activation energy, specific energy consumption, color parameters and chemical properties of dried fruits were examined and the effect of ripening levels and drying temperatures were investigated. In terms of drying duration, while full-ripe fruits dried in a shorter time, effective diffusion, activation energy and specific energy consumption values were found to be higher than semi-ripe fruits. In terms of color parameters, semi-ripe fruits are recommended to be dried at 50 or 60°C drying temperatures and full-ripe fruits should be dried at 50°C drying temperature for better preservation of color parameters. On the other hand, a common proper drying temperature could not be identified for acidity (pH), water soluble dry matter and titratable acidity.

Intermetallics Disappearance Rates and Intrinsic Diffusivities Ratios Analysis in the Cu-Zn and the Cu-Sn Systems

Intermetallics disappearance rates and intrinsic diffusivities ratios in the Cu-Zn system at temperature 400oC and in the Cu-Sn system at temperatures from 190oC to 250oC are analyzed theoretically using literature experimental data. Diffusion activation energies and pre-exponential coefficients for Cu-Sn system are calculated combining literature experimental results.

Intrinsic Diffusivities Ratio Analysis in the Al-Cu System

Copper and aluminium electric corrosion rates are investigated experimentally at room temperature and at temperature 100oC. It is founded that copper corrosion is higher than aluminium corrosion, and ratio of electric corrosion rates, kCu/kAl , decreases with temperature increasing. It is calculated that copper corrosion rate is approximately equal to aluminium corrosion at temperature about 300oC due to Cu2+ ions are less mobile than Cu+ ions. It is obvious physically: the higher temperature is, the grater atoms’ displacements in crystal lattice, Cu atoms can diffuse without two electrons, and Cu2+ ions more strongly interact with crystal lattice than Cu+ ions. A theoretical method to calculate intrinsic diffusivities ratio in double multiphase systems is proposed. The method involves the Kirkendall plane displacement and the general phases thickness only. Intrinsic diffusivities ratios in the Al-Cu system are calculated using literature experimental data. Diffusion activation energies and pre-exponential coefficients for the Cu-Al system are calculated combining literature experimental results. Analysis of literature data shows that the Kirkendall shift changes sign at temperature about 460oC in the Cu-Al system because of intrinsic diffusivities ratio, DCu*/DAl*, dependence from temperature. Such result agrees with copper and aluminium electric corrosion rates investigation.