Aluminum nitride (AlN) has versatile and intriguing properties, such as wide direct bandgap, high thermal conductivity, good thermal and chemical stability, and various functionalities. Due to these properties, AlN thin films have been applied in various fields. However, AlN thin films are usually deposited by high temperature processes like chemical vapor deposition. To further enlarge the application of AlN films, atomic layer deposition (ALD) has been studied as a method of AlN thin film deposition at low temperature. In this mini review paper, we summarize the results of recent studies on AlN film grown by thermal and plasma enhanced ALD in terms of processing temperature, precursor type, reactant gas, and plasma source. Thermal ALD can grow AlN thin films at a wafer temperature of 150~550 oC with alkyl/amine or chloride precursors. Due to the low reactivity with NH3 reactant gas, relatively high growth temperature and narrow window are reported. On the other hand, PEALD has an advantage of low temperature process, while crystallinity and defect level in the film are dependent on the plasma source. Lastly, we also introduce examples of application of ALD-grown AlN films in electronics.

Aluminum alloys are the light weight materials, they are commonly used in many industrial applications such as electronic, aerospace, automotive, and medical industry. Because they are used in these such applications. Therefore, their light weight and high surface quality are required. In this paper, the surface improvement round flat aluminum alloy using lapping finishing method was explored. In order to find the optimal condition, lapping parameters such as, rotational speeds, abrasive grain sizes of pad, processing times, and lapping oils were investigated in this study. The improvement in surface roughness was found to be highest with optimal condition at 200 rpm of rotational speed, 1 ㎛ abrasive grain size of pad, 0.5ml of light oil for 720 sec. By using the optimal condition, the initial surface roughness Ra of round flat aluminum alloy can be enhanced from 2.59㎛ to 0.02 ㎛. This can be concluded that the small CNC machine with lapping finishing method can be used to enhance the surface roughness of round flat aluminum alloy effectively.

An aluminium sandwich sheet is the composite adhered by rolling two aluminum panels to one plastic core. If it has the same bending stiffness as an steel sheets, it is about 65% lighter than steel sheet and 30% lighter than aluminum sheet. In present study, we intend to develop application technologies of an aluminum sandwich sheet for auto body panels from selecting composed materials of aluminium sandwich sheets to fabricating prototype. For this study, for the application of a light sandwich sheet to an automotive hood part, ribbing process so called, hemming for which joined between an inner and an outer panel was introduced. From these results, it was found that the sandwich sheet could improve the weight and maintain the flexural rigidity simultaneously comparing to the steel sheet.

This study provides an economical and effective method to improve the interlaminar properties of carbon fiber-reinforced polymers (CFRPs) using aluminum trihydroxide (ATH) microparticles. ATH microparticles are cheap and are expected to show good affinity to epoxies in the matrix and sizing agents of the carbon fibers owing to the presence of three hydroxyl groups. In addition, ATH particles are reported to improve the mechanical properties of polymers when used as the reinforcement. In this study, ATH microparticles of various sizes, 1.5, 10, and 20 μm, were used to improve the interlaminar properties of the CFRPs. ATH particles with a size of 1.5 μm improved the tensile properties of the ATH/epoxy resin and did not significantly alter the curing behavior. The interfacial adhesion between the carbon fiber and the epoxy resin was also improved, and the impregnation of the resin mixture remained similar to that of the neat resin, resulting in no significant void and defect formation. Considering the above results, the resulting 1.5 μm ATH-reinforced CFRP showed improved interlaminar properties compared to CFRP without ATH. However, 10 and 20 μm ATH-reinforced CFRPs showed deteriorated interlaminar properties due to the diminished tensile properties of the resin itself and resin impregnation, which resulted in more voids and defects, despite the interfacial adhesion between the fiber and the matrix resin.

Most structures require high reliability to ensure safety and soundness. The materials used for these structures are not only defective in the manufacturing process and construction process, but also cause generation and progress of defects due to operation of various complex use environments. In order to improve the reliability of the structure, it is very important to detect and estimate the defect size. The method of evaluating these defects without damaging the structure is a non-destructive method. In this paper, an aluminum probe of AC potential drop(ACPD) method is applied to the evaluation of two-dimensional artificial defects in ferromagnetic materials. Since the potential drop of the defect end is larger than that of the sound area, the defect can be detected and its position can be clearly confirmed, and the potential drops are changed according to the depth of the defect. The potential drop ratio (Vjmax/Vs) of the defective area has a large value for the defect. The relationship between the potential drop ratio (Vjmax/Vs) of 10 kHz and the defect depth can reduce the error in predicting the depth.

This is an experimental study where the coefficient of friction between engine pulley and V-Belt is obtained. The experimental method is applied pulleys made of existing steel and aluminium materials. The relative friction workpiece is a v-belt incorporating rubber with cloth. The friction test uses a pin-on-disk friction modulator and measures the coefficient of friction depending on the number of revolutions in the disc. As a result, in the case of aluminum material, there was a sliding phenomenon because the coefficient of friction was small when accelerating and decelerating. Also, the variation of the friction coefficient was severe when the rotation speed was increased or decreased. Therefore, it is considered that the aluminum pulley is slippery even if it is fit to the structural rigidity. Therefore, in order to secure a stable friction coefficient, the pulley groove surface will be surface-treated, a special alloy is added, or a heat treatment is required.

In aluminum brazing processes, corrosive flux, which is used in preventing oxidation, is currently raising environmental concerns because it generates many pollutants such as dioxin. The brazing process involving noncorrosive flux is known to encounter difficulties because the melting temperature of the flux is similar to that of the base material. In this study, a new brazing filler material is developed based on aluminum and non-corrosive flux composite powder. To minimize the interference of consolidation aluminum alloy powder by the flux, the flux is intentionally embedded in the aluminum alloy powder using a mechanical milling process. This study demonstrates that the morphology of the composite powder can be varied according to the mixing process, and this significantly affects the relative density and mechanical properties of the final filler samples.

In this study, we investigate the recycling of aluminum-based metal matrix composites(AMCs) embedded with SiC particulates. The microstructure of the AMCs is characterized by X-ray diffraction and scanning electron microscopy. The possibility of recycling the composite scrap is attempted from the melted alloy and SiC particulates by re-melting, holding and solidification in crucibles. The recovery percentage of the matrix alloy is calculated after a number of holding times, 0, 5, 10, 15, 20, 25 and 30 minutes and for different particulate sizes and weight fractions in the Al matrix. The results show that the recovery percentage of the matrix alloy, as well as the time required for maximum recovery of the matrix, is dependent on the size and weight fraction of SiC particulates. In addition, the percentage recovery increases with particulate size but drops with the particulate fraction in the matrix. The time to reach maximum recovery falls rapidly with an increase in particulate size and fraction.

The purpose of this study is to enhance heat insulation effect and to decrease fire hazard by attaching aluminum foil to expanded polystyrene, which is mainly used for insulating materials, to have fire retardant. The result of the test confirmed that the insulating materials, expanded polystyrene of 10 kg/m3 and 14 kg/m3 of density attached aluminum foil on both sides, showed 12%, 14% of improved heat transfer coefficient respectively compared to existing expanded polystyrene of the same density. Besides, they met all the standards for the testing of heat release and gas hazard. On the other hand, the one made of general expanded polystyrene could not meet the standards of the heat release test and the gas hazard test.

In this study, clinching characteristics of aluminum and galvanized steels were investigated for the application of clinching as a joining technique to aluminum wheelhouse assembly. A6451 aluminium alloy and galvanized steel sheets were joined by hybrid joining(clinching + adhesive bonding). Tensile-shear load and fracture mode of hybrid joints were investigated. Maximum tensile-shear load of hybrid joints was about six times higher than that of clinched joints without adhesive. Energy absorption values of hybrid joints were higher than those of clinched joints without adhesive as well as resistance spot welded steel joints. Developed aluminum wheelhouse assembly showed higher static stiffness than the existing steel parts. Aluminum wheelhouse inner panel unit was 44% lighter than the steel unit, and the final assembled aluminum wheelhouse was 14.6% lighter than the existing steel parts.

For the aerospace structural application of high-strength 2xxx series aluminum alloys, stress corrosion cracking(SCC) behavior in aggressive environments needs to be well understood. In this study, the SCC sensitivities of 2024- T62, 2124-T851 and 2050-T84 alloys in a 3.5% NaCl solution are measured using a constant load testing method without polarization and a slow strain rate test(SSRT) method at a strain rate of 10-6 /sec under a cathodic applied potential. When the specimens are exposed to a 3.5% NaCl solution under a constant load for 10 days, the decrease in tensile ductility is negligible for 2124-T851 and 2050-T84 specimens, proving that T8 heat treatment is beneficial in improving the SCC resistance of 2xxx series aluminum alloys. The specimens are also susceptible to SCC in a hydrogen-generating environment at a slow strain rate of 10−6/sec in a 3.5% NaCl solution under a cathodic applied potential. Regardless of the test method, low impurity 2124-T851 and high Cu/Mg ratio 2050-T84 alloys are found to have relatively lower SCC sensitivity than 2024-T62. The SCC behavior of 2xxx series aluminum alloys in the 3.5% NaCl solution is discussed based on fractographic and micrographic observations.

In this study, the effect of the content of MgO-CaO-Al2O3-SiO2 (MCAS) glass additives on the properties of AlN ceramics is investigated. Dilatometric analysis and isothermal sintering for AlN compacts with MCAS contents varying between 5 and 20 wt% are carried out at temperatures ranging up to 1600℃. The results showed that the shrinkage of the AlN specimens increases with increasing MCAS content, and that full densification can be obtained irrespective of the MCAS content. Moreover, properties of the AlN-MCAS specimens such as microhardness, thermal conductivity, dielectric constant, and dielectric loss are analyzed. Microhardness and thermal conductivity decrease with increasing MCAS content. An acceptable candidate for AlN application is obtained: an AlN-MCAS composite with a thermal conductivity over 70 W/m·K and a dielectric loss tangent (tan δ) below 0.6 × 10−3, with up to 10 wt% MCAS content.

In this study, the whole process of 6xxx series aluminum extruded alloy for high speed train interior and exterior parts are characterized. The mechanical properties, and chemical composition of the case materials were evaluated for the 6063, 6061 and 6N01 alloy profiles and compared to the commercial materials and the evaluation results satisfied the standard. The cast product was extruded using the air slip(AS) casting method and the direct casting(DC) method and these were again heat-treated conditions with T5 or T6. The remarkable point is that the extrusion temperature and pressure of 6061 alloy were somewhat higher than those of other alloys. The reason is that 6061 alloy exhibited brittle fracture due to grain boundary segregation even at the tensile fracture surface and the fact that the product used a billet by the direct casting method instead of air slip one. The mechanical properties were evaluated for the 6063, 6061, 6N01 extruded alloys and the evaluation results were analyzed and satisfied the standard properties.

In this study, MgO–CaO–Al2O3–SiO2 (MCAS) nanocomposite glass powder having a mean particle size of 50 nm and a specific surface area of 40 m2/g is used as a sintering additive for AlN ceramics. Densification behaviors and thermal properties of AlN with 5 wt% MCAS nano-glass additive are investigated. Dilatometric analysis and isothermal sintering of AlN-5wt% MCAS compact demonstrates that the shrinkage of the AlN specimen increases significantly above 1,300oC via liquid phase sintering of MCAS additive, and complete densification could be achieved after sintering at 1,600oC, which is a reduction in sintering temperature by 200oC compared to conventional AlN-Y2O3 systems. The MCAS glass phase is satisfactorily distributed between AlN particles after sintering at 1,600oC, existing as an amorphous secondary phase. The AlN specimen attained a thermal conductivity of 82.6 W/m·K at 1,600oC.

Intermetallic compound matrix composites have been expected to be established as high temperature structural components. Ni3Al is a representative intermetallic alloy, which has excellent ductility even at room temperature by adding certain alloying elements. Ni3Al matrix composites with aluminum oxide particles, which are formed by the in-situ reaction between the alloy and aluminum borate whiskers, are fabricated by a powder metallurgical method. The addition of aluminum borate whiskers disperses the synthetic aluminum oxide particles during sintering and dramatically increases the strength of the composite. The uniform dispersion of reaction synthesized aluminum oxide particles and the uniform solution of boron in the matrix seem to play an important role in the improvement in strength. There is a dramatic increase in strength with the addition of the whisker, and the maximum value is obtained at a 10 vol% addition of whisker. The Ni3Al composite with 10 vol% aluminum oxide particles 0.3 μm in size and with 0.1 wt% boron powder fabricated by the conventional powder metallurgical process does not have such high strength because of inhomogeneous distribution of aluminum oxide particles and of boron. The tensile strength of the Ni3Al with a 10 vol% aluminum borate whisker reaches more than twice the value, 930 MPa, of the parent alloy. No third phase is observed between the aluminum oxide and the matrix.

The US has invoked Article XXI of the GATT 1994 to justify its tariff measures on imports of steel and aluminum. However, the US’ tariff measures are not imposed for the protection of the US “essential security interests” but for economic and trade reasons. They do not satisfy the conditions listed under Article XXI (b) (i) to (iii) and should not be justified by them. They should not be considered as either national security measures or safeguard measures, but as ordinary trade restriction measures that are inconsistent with the WTO rules and the US obligations. A panel or the Appellate Body not only has the jurisdiction to review this dispute, but is also capable of making findings and providing a recommendation. Even if the US has the discretion to impose tariff measures under Article XXI (b), whether it has been acted in good faith, is still subject to the WTO review. As regards the tariff measures, the US has not acted in good faith.

MA Al alloys are examined to determine the effects of alloying of Mg and Cu and rolling on tensile deformation behavior at 748 K over a wide strain rate range(10−4-103/s). A powder metallurgy aluminum alloy produced from mechanically alloyed pure Al powder exhibits only a small elongation-to-failure(εf < ~50%) in high temperature(748 K) tensile deformation at high strain rates( = 1-102/s). εf in MA Al-0.5~4.0Mg alloys increases slightly with Mg content(εf = ~140% at 4 mass%). Combined addition of Mg and Cu(MA Al-1.5%Mg-4.0%Cu) is very effective for the occurrence of superplasticity(εf > 500%). Warm-rolling(at 393-492 K) tends to raise εf. Lowering the rolling-temperature is effective for increasing the ductility. The effect is rather weak in MA pure Al and MA Al-Mg alloys, but much larger in the MA Al-1.5%Mg-4.0%Cu alloy. Additions of Mg and Cu and warm-rolling of the alloy cause a remarkable reduction in the logarithm of the peak flow stress at low strain rates ( < ~1/s) and sharpening of microstructure and smoothening of grain boundaries. Additions of Mg and Cu make the strain rate sensitivity(the m value) larger at high strain rates, and the warm-rolling may make the grain boundary sliding easier with less cavitation. Grain boundary facets are observed on the fracture surface when εf is large, indicating the operation of grain boundary sliding to a large extent during superplastic deformation.