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Fe-36%Ni alloy has been widely used for bimetal and shadow masks in cathode ray tubes and structural materials of LNG storage tanks because of its low thermal expansion coefficient. The purpose of this study is to evaluate the effects of reheating environments(excess oxygen and SO₂ content) and strain rate on the oxidation properties and hot workability of Fe-36%Ni alloy. The internal oxidation increased with increasing excess oxygen and SO₂ contents in environments arid with increasing reheating temperatures. Under the conditions containing low excess oxygen and no SO₂ in environments, the weight gain behavior is minimized because of the formation of FeO instead of Fe₃O₄ or Fe₂O₃ in the external scale. It is also found that the hot workability of Fe-36%Ni alloy decreased with decreasing strain rate due to the dominating intergranular fracture and the one is improved under the non-oxidation reheating environments by preventing the notch effect arisen from internal oxidation.

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The effect of intercritical heat treatment (IHT) and tempering conditions on impact toughness and strength in a Mn-Mo-Ni low alloy pressure vessel steel (SA508 Gr.3 steel) has been investigated. The optimum condition of the IHT for toughness improvement was developed. The application of IHT resulted in the increase of ductility and upper shelf energy and in the decrease of strength and ductile-to-brittle transition temperature (DBTT). The modification of tempering conditions reduced the loss of strength resulting from the IHT and maximized toughness improvement. The beneficial effects from the IHT were consistently maintained in spite of the changes of heating and cooling rates. Additionally, the cause of the increase in toughness was investigated in relation to the microstructural change. The IHT produces a composite structure of hard martensite and soft tempered bainite. Tempering following IHT results in spheroidization of carbides and finer effective grain size, which enhance resistance to the brittle fracture.

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Recently, it has become increasingly difficult for only a single metallic material to meet the demand, which asks for the effective charateristics, such as mechanical properties and electric conductivity, at the same time. The development of clad material, which consists of two or more metals, has risen in which the clad material has developed advanced fuctional properties by utilizing the property of each metal. In this paper, Al/Cu clad composite material fabricated by indirect extrusion method which has similar advantage of hydrostatic extrusion method there is no friction between billet surface and container in. It was to find the suitable extrusion conditions on working criterion and bonding charateristics of interface along the variation of extrusion conditions and heat treatment temperature.

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Copper-based leadframe sheets were oxidized in hot alkaline solutions to form brown and black oxide layers on the surface, molded with the epoxy molding compound (EMC), and machined to form sandwiched double cantilever beam (SDCB) and sandwiched Brazil-nut (SBN) specimens. The two types of specimens were designed to measure the adhesion strength of the leadframe/EMC interfaces under quasi-Mode I (G_(IC)) and mixed Mode loadings (G_c), respectively. Results showed that both oxide layers enhanced G_(IC) to the level of ∼80 J/㎡ at two minutes of the oxidation time. G_c increased parabolically with phase angle when the sign of phase angle was positive. For both cases, interface crack began to kink into EMC when G_c was ∼150 J/㎡.

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Degradation process of WC-Co coating was evaluated through analyses of a coated stabilizing roll used in a molten zinc pot of a CGL(Continuous Galvanizing Line) for 56 days. The roll was coated by high velocity oxygen fuel spraying with the WC-12%Co powder that was produced through sintering and crushing process. According to observation of the coating cross-section with SEM, the Zn and Al diffused into the coating layer with the same depth but the Fe in a zinc bath did not diffuse into the coating. Dross particles deposited on the pot rolls were analyzed to be Fe₂Al_5 by X-ray diffraction pattern analysis. Final reaction products of WC-Co coating with zinc bath have nearly the same chemical compositions as the Fe₂Al_5 dross. This phase acted as a diffusion barrier against Zn, Al and Co diffusion at the interface of molten zinc/spray coating and consequently diffusions of Al and Zn were suppressed in the coating layer under this phase.

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(TiAl)N films deposited by cathodic arc process employing two separate targets of Al and Ti have lots of macro-particles on the surface. The macro-particles were found out to be generated mainly from Al cathode of low melting temperature. In the previous study, TiN films deposited with external magnetic field showed remarkable reduction of surface droplet. For the (TiAl)N coatings, however, the efficiency of Al droplet removal was not so much as TiN films. A new coating concept combining magnetron sputtering and arc evaporation for improved coating properties was made in this study. (TiAl)N and Al-gradient (TiAl)N coatings were deposited by arc-magnetron hybrid process and content of Al in the films was changed by power density of Al magnetron sputtering source. This hybrid process allowed compositionally gradient (TiAl)N coatings to be deposited with low macro-particles and excellent adhesion. It is noted that Al-gradient (TiAl)N coating showed micro hardness of 3,000 ㎏/㎟ and good adhesion of HF2 grade. The present study introduces the hybrid process parameters involved. The formation behavior of (TiAl)N and Al-gradient (TiAl)N coatings were investigated by SEM, EDX AES and XRD.

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Amorphous silicon was crystallized by metal induced lateral crystallization(MILC) in an electric field. A 50 Å Ni layer on a-Si was used for the crystallization and 3000 Å Pt layers for the electrodes. In a DC electric field over 200 V/㎝, MILC rate of a-Si with negative polarity increased and with positive polarity decreased. In an AC electric field over 2200 V/㎝, MILC rate increased and this phenomenon can be explained by Joule heating effect.

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All-solid-state rechargeable thin film batteries were fabricated with the cell structure of Li/Lipon/LiMn₂O₄ by using of sequential thin film deposition techniques. Planar type multi-microbatteries were realized by connecting eight cells in parallel and in series via planar metalization. In the parallel connected thin film batteries, the discharge capacity was increased linearly depending on the number of unit cell. From the investigation of discharge current density effects on discharge curves of thin film batteries connected in parallel, the rate capability was greatly improved due to the increase of lithium intercalations kinetics for charge transfer. In the serially-connected thin film batteries, the output voltage as high as approximately 32 V was obtained by the serial connection of eight unit cells.

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Activity of Na₂O in the Na₂O-B₂O₃ slag at 1373K was measured by using thermochemical equilibration technique. The activity of Na₂O increases from 1.86× 10^(-6) to 4.99×10^(-4) with increasing Na₂O content from 11.0 to 64.9% in molar basis. The activities of Na₂O and B₂O₃ in the molten slag indicated that each component shows significant negative deviation from an ideality. None of the peak is observed in the relationship between the stability function and slag composition. The (excess) stability significantly changes at the composition of X_(Na2O) = 0.25 and 0.60, indicating the difference of the network structure of the borate melt at these compositions. The change of the partial molar Gibbs free energy of mixing, theoretical optical basicity, and the lattice energy was introduced to understand the thermodynamic behavior of Na₂O-B₂O₃ melt. As a result, the thermodynamic behavior of the Na₂O-B₂O₃ system with various slags can be explained more quantitatively by the lattice energy in the present study. In addition, the dependence of the activity coefficient of sodium in molten silver on Na content at 1373K can be expressed by the following equation. In γ_(Na) = 11.5(1-X_(Na))²-8.13 (0 $lt; X^(Ag)_(Na) $lt; 0.005).

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