• Journal of Welding and Joining
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• v.15 no.6
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• pp.32-40
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• 1997

Solid state diffusion bonding is the joining process performed by creep and diffusion, which is accelerated by heating below melting temperature and proper pressing, in vacuum or shielding gas atmosphere. By this process we can obtain sufficient joint which can't be expected from the fusion welding. For Ti-6Al-4V alloy, the optimum solid state diffusion bonding condition and mechanical properties of the joint were found, and micro void morphology at bond interface was observed by SEM. The results of tensile test showed sufficient joint, whose mechanical properties are similar to that of base metal. 850$^{\circ}$C, 3MPa is considered as the optimum bonding condition. Void morphology at interface is long and flat at the initial stage. As the percentage of bonded area increases, however, small and round voids are found. Variation of void shape can be explained as follows. As for the void shrinkage mechanism, at the initial stage, power law creep is the dominant, but diffusion mechanism is dominant when the percentage of bonded area is increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2522-2527
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• 2011

Technology policy has a substantial impact on the diffusion of a new technology. This paper uses technology policy as a variable in the general epidemic model to quantify the effects of the policy on technology diffusion. The results obtained in this study, using data on solid-state technology diffusion in the U.S. indicate that technology policy plays a positive role in technology diffusion and provide a firm basis for understanding the relationship between technology policy and technology diffusion through the use of quantitative data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.481-485
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• 2003

To diffuse Zn at solid-state, the $SiO_2/ZnO/SiO_2$ wafers was made by PECVD and RF Spotter. Thicknesses of bottom $SiO_2$ and cap $SiO_2$ was about $500{\AA}$ and about $3500{\AA}$. First test was Diffusion temperatures were $760^{\circ}C$, $780^{\circ}C$, and $800^{\circ}C$, and diffusion times were 1, 2, 3, 4, 5, and 6 hr and 2nd test was Diffusion temperatures were $760^{\circ}C$, $720^{\circ}C$, and $680^{\circ}C$, and diffusion times were 1, 2, 3, 4, 5, and 6 hr. LED chips were fabricated by the diffused wafers at Fab. The peak wavelength of all chips showed about $625{\sim}650\;nm$ and red color Main reason for Iv change was by diffusion temperature not diffusion time. The lower temperature was the higher Iv. We thick that these properties is because of the very high diffusion temperature.

• Journal of Welding and Joining
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• v.10 no.3
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• pp.63-72
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• 1992

The joining methods of ceramics to metals which can be expected to obtain high temperature strength are mainly classified into the solid-state diffusion bonding method and the active brazing method. Between these two, the solid-state diffusion bonding method is given attentions as substituting method for active brazing method due to being capable of obtaining higher bonding strength at high temperature and accurate bonding. In this paper, the solid-state diffusion bonding of $Al_{2}$O$_{3}$ ceramics to Ni-Cr-Mo alloy steel (SNCM21) using insert metal was carried out. The insert metal employed in this study was experimentally home-made, Ag-Cu-Ti alloy. Influence of several bonding parameters of $Al_{2}$O$_{3}$SNCM21 joint was quantitatively evaluated by bonding strength test, and microstructural analyses at the interlayer were performed by SEM/EDX. From above experiments, the optimum bonding condition of the solid-state diffusion bonding of $Al_{2}$O$_{3}$/SNCM21 using Ag-Cu-Ti insert metal was determined. Futhermore, high temperature strength and thermal-shock properties of $Al_{2}$O$_{3}$/SNCM21 joint were also examined. The results obtained are as follows. 1. The maximum bonding strength was obtained at the temperature of 95% melting point of insert metal. 2. The high temperature strength of $Al_{2}$O$_{3}$/SNCM21 joint appeared to bemaximum value at test temperature 500.deg.C and the bonding strength with increasingtemperature showed parabolic curve. 3. The strength of thermal-shocked specimens was far deteriorated than those of as-bonded specimens. Especially, water-quenched specimen after heated up to 600.deg. C was directly fractured in quenching.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.6
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• pp.300-306
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• 2008

Solid state diffusion brazing of aluminum castings (AC4C) and wrought alloys (Al6061) was conducted in order to improve thermal conductivity and temperature uniformity of the aluminum heater which was generally fabricated by casting method. Tensile strength and thermal conductivity are raised with increasing brazing temperature, obtaining 122.5 MPa and $206W/m{\cdot}K$ at $540^{\circ}C$ 5hrs brazing conditions, respectively. The diffusion brazed heater, shows maximum temperature difference of $4^{\circ}C$, exhibits a enhanced temperature uniformity compared with the cast heater having the maximum temperature difference of $11^{\circ}C$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1999.04a
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• pp.5-5
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• 1999

The Principal deficiency of the existing notion about the sintering-mixtures consists in the fact that almost no attention is focused on the Phenomenon of alloy formation during sintering, its connection with dimensional changes of powder bodies, and no correct ideas on the driving force for the sintering process in the stage of establishing chemical equilibrium in a system are available as well. Another disadvantage of the classical sintering theory is an erroneous conception on the dissolution mechanism of solid in liquid. The two-particle model widely used in the literature to describe the sintering phenomenon in solid state disregards the nature of the neighbouring surrounding particles, the presence of pores between them, and the rise of so called arch effect. In this presentation, new basic scientific principles of the driving forces for the sintering process of a two-component powder body, of a diffusion mechanism of the interaction between solid and liquid phases, of stresses and deformation arising in the diffusion zone have been developed. The major driving force for sintering the mixture from components capable of forming solid solutions and intermetallic compounds is attributed to the alloy formation rather than the reduction of the free surface area until the chemical equilibrium is achieved in a system. The lecture considers a multiparticle model of the mixed powder-body and the nature of its volume changes during solid-state and liquid-phase sintering. It explains the discovered S-and V-type concentration dependencies of the change in the compact volume during solid-state sintering. It is supposed in the literature that the dissolution of solid in liquid is realised due to the removal of atoms from the surface of the solid phase into the melt and then their diffusicn transfer from the solid-liquid interface into the bulk of liquid. It has been shown in our experimental studies that the mechanism of the interaction between two components, one of them being liquid, consist in diffusion of the solvent atoms from the liquid into the solid phase until the concentration of solid solutions or an intermetallic compound in the surface layer enables them to pass into the liquid by means of melting. The lecture discusses peculimities of liquid phase formation in systems with intermediate compounds and the role of the liquid phase in bringing about the exothermic effect. At the frist stage of liquid phase sintering the diffusion of atoms from the melt into the solid causes the powder body to grow. At the second stage the diminution of particles in size as a result of their dissolution in the liquid draws their centres closer to each other and makes the compact to shrink Analytical equations were derived to describe quantitatively the porosity and volume changes of compacts as a result of alloy formation during liquid phase sinteIing. Selection criteria for an additive, its concentration and the temperature regime of sintering to control the density the structure of sintered alloys are given.

• 전기의세계
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• v.20 no.6
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• pp.19-21
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• 1971

Permittivities are closely related to lattice vibrations and dispersions relations, and this paper deals with the tensor permittivities which include the effect of diffusion. It is a great convenience in the consideration of plasma waves to treat the plasma as a dielectric medium with its circumference. And, on the assumption that the motion of the ionized donors be neglected the general expression from which the tensor permittivity can be derived is derived from the view point that the plasma can be treated as a hydrodynamical fluid. The effect of diffusion appears as perturbation terms in the tensor permittivities of the non-streaming solid state electron magnetoplasmas and affects no influence on the anisotropic terms in the specific configuration.

• 전기의세계
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• v.22 no.3
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• pp.35-48
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• 1973

This paper deals with wave propagations in solid state electron plasmas from the view point of treating the plasma as a conducting fluid, and especially consideration is extended to the effect of diffusion on the permittivities and dispersion relations. The analysis is based on the conception of the self-consistent field approximation. It is shown for the cases of the specific physical configurations that the positions of the null elements in the permittivity tensors are not affected by the diffusion terms, and the diffusion effect appears only in the case of the space-charge wave. It is also shown that the magnitude of the real part of wave vector is in proportion to the 3/2nds power of the field in some regions.

• 한국기계연구소 소보
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• s.13
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• pp.65-73
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• 1984

• Proceedings of the KWS Conference
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• 1990.11a
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• pp.45-49
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• 1990