Properties of coatings produced by warm spray were investigated in order to utilize this technique as a repair method for Al tire molds. Al-(0-10 %)Al2O3 composite powder was sprayed on Al substrate by warm spraying, and the microstructure and mechanical properties of the composite coating layer were investigated. For comparative study, the properties of the coating produced by plasma spray, which is a relatively high-temperature spraying process, were also investigated. The composite coating layers produced by the two spray techniques exhibited significantly different morphology, perhaps due to their different process temperatures and velocities of particles. Whereas the Al2O3 particles in the warm sprayed coating layer maintained their initial shape before the spray, flattened and irregular shape Al2O3 particles were distributed in the plasma sprayed coating layer. The coating layer produced by warm spray showed significantly higher adhesive strength compared to that produced by plasma spray. Hardness was also higher in the warm sprayed coating layer compared to the plasma sprayed one. Moreover, with increasing the fraction of Al2O3, hardness gradually increased in both spray coating processes. In conclusion, an Al-Al2O3 composite coating layer with good mechanical properties was successfully produced by warm spray.

This study was carried out to investigate the optimum condition of a friction stir welding process for a joint of AA2219-T87 and AA2195-T8 dissimilar aluminum alloys. These alloys are known to have good cryogenic properties, and as such to be suitable for use in fuel tanks of space vehicles. The welding parameters include the travelling speed, rotation speed and rotation direction of the tool. The experiment was conducted under conditions in which the travelling speed of the tool was 120-300 mm/min and the rotation speed of the tool was 400-800 rpm. To investigate the effect of the rotation direction of the tool, the joining was performed by switching the positions of the two dissimilar alloys. After welding, the microstructure was observed and the micro-hardness were measured; non-destructive evaluation was carried out to perform tensile tests on defect-free specimens. The result was that the microstructure of the weld joint underwent dynamic recrystallization due to sufficient deformation and frictional heat. The travelling speed of the tool had little effect on the properties of the joint, but the properties of the joint varied with the rotation speed of the tool. The conditions for the best joining properties were 600 rpm and 180-240 mm/min when the AA2219-T8 alloy was on the retreating side(RS).

In this study, the laser welding experiments were performed with the 1 mm thickness of Al 6061-T6 using by 5 kW fiber laser welding system. The optimum laser welding condition of the lap joint has been investigated by analyzing the penetration depth and the porosity fraction through observation of the cross-sections. Based on the test results, the sound joint was obtained from the welding condition with the power of 2 kW and the focal position of -0.8 mm at the continuous laser welding speed of 2 mpm. Also, the tensile strength of the sound joint after heat treatment(170℃, 12hr) was increased almost 87% that of the base material. Especially, the fatigue test result of the sound joint showed that the fatigue cycle was 3×10 4 at the highest test load of 100 MPa.

In this study, we changed the existing S45C steel shafts applied to the drive shaft for power train of automotive to Al7003-T6 aluminum material. For this purpose, the optimal inner diameter of the aluminium shaft is established. And, analysis of the stresses and vibration characteristics of shafts were analyzed through finite element analysis. The final aluminum drive shaft was evaluated through the static torsional torque test and the frequency test. The Al7003-T6 aluminum drive shaft's weight is 67% comparing from 100% of shaft with existing steel, and with the performance of 3,276 N-m and 236 Hz, it satisfies requirements of the torsional torque of 3,000 N-m and vibration characteristic over 150 Hz required for drive shaft.

In this paper, a 2-DOF electromechanical impedance model of PZT material-aluminum interface member is proposed. The primary motivation is to control the effective frequency range in impedance-based local health monitoring practices. The proposed method focuses on the predetermination of the effective frequency band and the wireless impedance sensing possibility for damage detection in structural connections like tendon anchorage, etc. Firstly, a 2-DOF impedance model is proposed for modelling the PZT interface-host structure system. Secondly, the prototype design of the PZT interface is developed based on the analysis of the 2-DOF impedance model and the local dynamic characteristics of the composite aluminum interface-host structure system. Finally, the feasibility of the proposed 2-DOF impedance model is numerically verified by predetermining the effective frequency band for the impedance monitoring in a cable-anchorage connection.

In this study, the fracture property of the bonded structure with aluminum foam is analyzed by using the closed aluminium foam for impact absorber. DCB and TDCB specimens manufactured with the single lap joint method of mode 3 are designed by varying the thickness. The static analysis through ANSYS finite element program is carried out on the specimen model due to each thickness. Also, the static experiment is performed in order to verify the analysis result. This study aims at comparing the shear strengths of the bonded structures of DCB and TDCB made with aluminum foam and investigating the mechanical properties.

Bridge inspection structures are the structure which is installed on the piers, abutments, and copings for the inspection and maintenance of substructure. In this study, the structural performance of the bridge inspection structures using aluminum members manufactured by extrusion process is evaluated. The bridge inspection structures can be installed regardless of the shape of concrete surface through the simple cutting process. The structural performance of bridge inspection structures is evaluated using FE analysis. Moreover, experimental studies are conducted for the estimation of the structural safety of the members for the design load.

An aluminum with the light weight has been used at the automotive car body. As the aluminum is applied to the automotive seat, the optimum design becomes important by investigating the mechanical properties. This study aims at suggesting the basic data for the optimum design of automotive seat frame. In this study, the mechanical properties are investigated through the simulation analysis on the entire structure of seat frame. Two study models using the real commercial vehicles are designed with CATIA program and analyzed with ANSYS program. The harsh condition during the driving state is supposed by using the analyses of natural frequencies and harmonic responses. As the real frequency ranges in this study are set by selecting the natural frequencies through modal analysis. The critical frequencies are analyzed by harmonic response on which the driver is seated. The values of maximum equivalent stresses at models 1 and 2 are shown to be 18.073MPa and 2259.2MPa respectively. The critical frequency at models 1 and 2 are also shown to be 77 Hz and 206 Hz. The maximum stress at model 1 becomes far bigger than model 2. By comparing two models, model 1 has more critical condition than model 2. At the design of automotive seat frame at the dynamic vibration condition, the material of design with the durability and safety can be secured through this study result.

We developed an Al sputtering process by varying the plasma power, process temperature, and film thickness. We observed an increase of hillock distribution and average diameter with increasing plasma power, process temperature, and film thickness. Since the roughness of a film increases with the increase of the distribution and average size of hillocks, the control of hillock formation is a key factor in the reduction of Al corrosion. We observed the lowest hillock formation at 30 W and 100 oC. This growth characteristic of sputtered Al thin films will be useful for the reduction of Al corrosion in the future of the electronic packaging field.

Composite materials consisting of pure aluminum matrix reinforced with different amounts of graphite particles are successfully fabricated by mechanical ball milling and spark plasma sintering (SPS) processes. The shrinkage rates of the composite powders vary with the amount of graphite particles and the lowest shrinkage value is observed for the composite with the highest amount of graphite particles. The current slopes of time increase with increase in the amount of graphite particles whereas the current slopes of temperature show the opposite trend. The highest thermal conductivity is achieved for the composite with the least amount of graphite particles. Therefore, the thermal properties of the composite materials can be controlled by controlling the amount of the graphite particles during the SPS process.

As a part of light weight, the adhesive has been applied to joint the mechanical structure. The porous material is used with aluminum foam in case of the structure bonded with only adhesive. In order to confirm the durability, it is necessary to investigate the fracture toughness at the bonded joint. So, the fracture property at joint interface of aluminum foam different from the non-porous material becomes especially important. In this study, the tapered double cantilever beams(TDCB) with the type of mode Ⅲ are manufactured with aluminum foam. The fracture toughness at the joint of the structure bonded with only a adhesive can be obtained. The static analyses are carried out and verified the results by the experiment. As the results of static analyses, the reaction forces ranged from 0.30 to 0.41 kN at all specimens are shown when the forced displacements are proceeded as much as 7 to 9 mm. As the results of analyses and experiments are compared with each other, there is a little bit of difference between these results. Through the result of this study, the mechanical properties at TDCB specimens with the type of mode Ⅲ can be understood.

In this study, the fracture property of impact absorption is investigated using the carbon fiber composite material. And this property is compared with the carbon fiber composite material with aluminum foam. Carbon fiber composite material has the high specific strength and rigidity and the superior durability and fatigue life and light weight. On the ground of these properties, this material has been used widely at the fields of airplane, national defence industry, vehicle and the various industrial areas. Aluminum foam can also be applied at the various areas as it is the material with the superior properties. And this foam is the material which can solve the problem on the light weight of particular product. At the condition of the impact energy of 20J, the maximum loads of CFRP sandwich composite and CFRP sandwich composite with aluminum foam core are shown to be 5.7 kN and 6.5 kN respectively. In case of maximum energies, these values are shown to be 19 J and 17.5 J respectively. At the impact energy of 50 J, the maximum loads of CFRP sandwich composite and CFRP sandwich composite with aluminum foam core are shown to be 7 kN and 8.8 kN respectively. In case of maximum energies, these values are shown to be 43 J and 48 J respectively. At the impact energy of 80 J, the maximum loads of CFRP sandwich composite and CFRP sandwich composite with aluminum foam core are shown to be 9.2 kN and 11 kN respectively. In case of maximum energies, these values are shown to be 70 J and 63 J respectively. As the result of this study, the mechanical properties are investigated through the impact experiments on the composites composed of the closed aluminum foam and the carbon fiber reinforced plastic used frequently as absorbents.

Phosphorus (P) removal by aluminum sulfate solution was investigated with varying pH and initial P concentrations. P removal was the highest at around pH 6. The pH range where P removal occurred was slightly wider at higher initial P concentrations. Compared to theoretical calculations, it was confirmed that AlPO4 precipitation was the main reason for P removal at low pH. At high pH, where there should be no AlPO4 precipitates, the P removal by adsorption of amorphous Al(OH)3 precipitates was experimentally observed. The P removal by adding amorphous Al(OH)3 precipitates prepared before the adsorption experiments, however, was lower than that by injecting aluminum sulfate solution because the prepared precipitates became larger, leading to less specific surface area available for adsorption. Ions other than sulfate had little influence on P removal.