• Proceedings of the KOSOMBE Conference
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• v.1989 no.05
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• pp.9-12
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• 1989

A preliminary study has been conducted to demonstrate the effect of laser heat treatment on Ni Ti alloy dental arch wires ($0.016"\;{\times}\;0.022"$ and $0.018"\;{\times}\;0.026"$, rectangular shape). Changes in mechanical and thermal properties and surface morphologies are investigated by using optical and scanning electron microscope (SEM), energy dispersive x-ray microprobe analysis(EDX), differential scanning calorimeter (DSC), and micro hardness tester. The results indicate that the laser can affect the thermal equilibrium state of the localized surface. Titanium rich surface film is formed by the laser treatment. The surface film and rapidly resolidified underlying structures show better chemical resistance than the matrix material. Phase transition temperatures which are related to shape recovery temperatures are changed after laser treatment. Hardness of resolidified area and heat affected zone are lower than before treatment.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.245-245
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• 1998

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.1
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• pp.1-6
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• 2002

Alkaline sizing characteristics of TMP (thermomechanical pulp) handsheets with AKD (alkylketene dimer) were studied under various conditions. The sizing degree of TMP handsheet was much lower than that of chemical pulp. Especially, the sized TMP handsheet dried at $20^{\circ}C$ showed no sizing features, but sizing degree of TMP handsheet was clearly Increased by heat treatment at $105^{\circ}C$. The sizing effect of TMP was also improved by addition of $CaCO_3$, but it was not affected by pH. Therefore, sizing effect of TMP with AKD can be improved to some extent by controlling stock condition and heat treatment of handsheet.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.352-361
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• 2005

In this study, conventional head-end processes of spent TRISO fuel have been reviewed to develope more effective treatment methods. The main concerns in the TRISO treatment are to effectively separate the carbon and SiC contained in the TRISO particles. The crush-burn scheme which was considered in the early stages of the development has been replaced by the crush-leach process because of $^{14}C$ problems as a second waste during the process. However there are still many obstacles to overcome in the reported processes. Hence, innovative thermomechanical concepts to breach the coating layers of the TRISO particle with a minimized amount of second waste are proposed in this paper and their principles are described in detail.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.253-261
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• 1994

Transformation behavior and superelastic behavior of Ti-Ni-Cu alloys with various Cu content has been investigated by means of electrical resistivity measurement, X-ray diffraction, tensile test and transmission electron microscopy. Two types of heat treatment are given to the specimens: i) Solutions treatment. ii) thermo-mechanical treatment. The transformation sequence in solution treated Ti-Ni-Cu Alloys substituted by Cu for Ni up to 5at.% occurs to $B2{\rightleftarrows}B19^{\prime}$ and it proceeds in two stages by addition of 10at.%Cu, i. e, $B2{\rightleftarrows}B19{\rightleftarrows}B19^{\prime}$. Also, it has been found that Ti-30Ni-20Cu alloy transformed in one stage : $B2{\rightleftarrows}B19$. The thermo-mechanically treated Ti-47Ni-3Cu alloy transformed in two stages: B2${\rightleftarrows}$rhomboheral phase${\rightleftarrows}B19^{\prime}$, while transformation sequence in Ti-45Ni-5Cu and Ti-40Ni-10Cu alloy transformed as same as solution treated specimens. The critical stress for inducing slip deformation in solution treated and thermo-mechanically treated Ti-40Ni-10Cu alloy is about 90MPa and 320Mpa respectively.

• Journal of the Korean Wood Science and Technology
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• v.25 no.2
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• pp.75-80
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• 1997

This research has been examined to measure the degree of the fiber damage of ozonenation high yield pulp in the beating process. Ozone treated the TMP(Thermomechanical Pulp) and CTMP(Chemithermomechanical Pulp) of spruce and the CTMP of birch has been beaten to be reached 200ml(freeness) of its content. It had been studied the forming of fiber distribution by treatment for long fiber, short fiber, fine with the above method. As ozone treatment time gets longer, the pulp has showed the tendency of increasing the fiber content of 28, 48mesh. Ozone treated fiber has been increased long fiber content by being added softness. By given longer ozone treatment time, the TMP and CTMP of spruce has showed the decreasing of fiber content. On the contrary, CTMP of birch has showed the increasing its fiber content. It had proved that the results of difference are rather closer to the species of tree than closer to the kinds of pulp. The fiber content of over 200mesh which has created in beating process demonstrates the decreasing of its fiber content by getting longer ozone treatment time. The softness of fiber can be extracted by the lignin of fiber surface that had been formed by ozone treatment. Thus we assume that the fiber in the process of beating obtains less physical damage.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.424-429
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• 2003

Hot gas path components, which are made of nickel based superalloys, are subject to periodic replacement due to degradation of thermomechanical properties that might bring catastrophic failure during normal operation of gas turbine units. In order to rejuvenate the metallurgical condition of the serviced components, heat treating techniques such as solution annealing and aging heat treatments have widely been employed. However, the effectiveness of those typical heat treatments is not apparent enough in terms of quantitative grounds. On the other hand the demand of the rejuvenation heat treatment and hot isostatic pressing (HIP) have constantly been raised by the end users. Therefore it is necessary to verify how the typical heat treating techniques affect to the aged and degraded material. As the result of experimental work in this study, GTD-111 and GTD-222 Ni-based superalloys were collected and analyzed quantitatively through microscopic observation, microhardness evaluation and creep test.

• Structural Engineering and Mechanics
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• v.22 no.5
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• pp.517-539
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• 2006

Friction problems involving rubber components are frequently encountered in industrial applications. Their treatment within the framework of numerical simulations by means of the Finite Element Method (FEM) is the main issue of this paper. Special emphasis is placed on the choice of a suitable material model and the formulation of a contact model specially designed for the particular characteristics of rubber friction. A coupled thermomechanical approach allows for consideration of the influence of temperature on the frictional behavior. The developed tools are implemented in the commercial FE code ABAQUS. They are validated taking the sliding motion of a rubber tread block as example. Such simulations are frequently encountered in tire design and development. The simulations are carried out with different formulations for the material and the frictional behavior. Comparison of the obtained results with experimental observations enables to judge the suitability of the applied formulations on a structural scale.

• Journal of Powder Materials
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• v.6 no.1
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• pp.111-118
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• 1999

Ni(Fe)Al powders containing a homogeneous distribution of the in-situ formed AIN and $Al_2O_3$ dispersoids have been produced by mechanical alloying process in a controlled atmosphere using high energy attrition mill. The powders have been successfully consolidated by hot extrusion process. The phase information investigated by TEM and XRD analysis reveals that Fe can be soluble up to 20% to the NiAl phase ($\beta$) at room temperature after MA process. Subsequent thermomechanical treatment under specific condition has been tried to induce secondary recrystallization (SRx) to improve high temperature properties, however, the clear evidence of SRx was not obtained in this material. Mechanical properties in term of strength at room temperature as well as at high temperatures have been improved by the addition pf AIN, and the room temperature ductility has been shown to be improved after heat treatment, presumably due to the precipitation of second phase of $\alpha$ in this material.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.5
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• pp.226-232
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• 2021

The relationship between precipitation and coefficient of thermal expansion of Al-6%Si-0.4%Mg-0.9%Cu-(Ti) alloy (in wt.%) after various heat treatments were studied by the thermodynamic analyzer (TMA) and differential scanning calorimetry (DSC). Solution heat treatment of the alloy was carried out at 535℃ for 6 h followed by water quenching, and the samples were artificially aged in the air at 180℃ and 220℃ for 5 h. The coefficient of thermal expansion (CTE) curve showed some residual strain and decreased with increasing aging temperature. The CTE curves changed sharply in the temperature range of 200℃ to 400℃, and the corresponding peak shifted for the aged samples due to the change in the precipitation behavior of the secondary phase. These transformation peaks in the aged sample are related to the volume of the precipitation of the Si phase as determined by DSC analysis. The change in CTE is mainly caused by the precipitation of the Si phase in the Al-Si alloy, and the size of the change occurs simultaneously with the size of the precipitate.