• Journal of the Korean Wood Science and Technology
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• v.40 no.2
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• pp.91-100
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• 2012

This study analysis the effect of various temperatures (20, 35 and $50^{\circ}C$) on the formaldehyde emission from wood composites, which were particleboard (PB), medium density fiberboard (MDF), high density fiberboard (HDF) and laminated HDF (L-HDF) by Japanese desiccator method. Also, to reduce formaldehyde emission by wood composites, it has been suggested that undergo a bake-out conditions. On average, the level of formaldehyde emission increased many times with a $15^{\circ}C$ increase in temperature from 20 to $35^{\circ}C$ for PB, MDF, HDF and L-HDF, respectively. Formaldehyde emissions from wood composites could be expected to increase with increasing ambient temperature. At $35$ for 28 days bake-out treatment of boards, the free formaldehyde emission reduced 67.8% (PB), 40.1% (MDF), 37.8% (HDF), and 35.2% (L-HDF). On the other hand, after the bake-out at $50^{\circ}C$ for 28 days, the formaldehyde concentration decreased by 88.2, 66.9, 62.2 and 59.3% of the concentration before the bake-out for PB, MDF, HDF and L-HDF, respectively. An interesting of the bake-out treatment at $50^{\circ}C$ after 14 days, formaldehyde emission grade of PB & MDF down $E_2$ to $E_1$, and HDF & L-HDF down $E_1$ to $E_0$.

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.448-453
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• 2011

Pre-aging heat treatment after solution heat treatment (SHT) of Al-0.4 wt%Mg-1.2 wt%Si-0.1 wt%Mn alloy sheets for auto-bodies was carried out to investigate the effect of pre-aging and its conditions on the bake-hardening response. Mechanical properties were evaluated by a tensile and Vickers hardness test. Microstructural observation was also performed using a transmission electron microscope (TEM). It was revealed that pre-aging treatments play a great role in the bake-hardening response. In addition, it was found that the sphere-shaped nanosized clusters that can directly transit to the needle-shaped ${\beta}$" phase during the paint-bake process, not being dissolved into the matrix, are formed at 343 K. The result, reveals that the dominant factor of the bake-hardening response is the pre-aging temperature rather than the pre-aging time.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.4
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• pp.161-172
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• 2020

The tensile property of A5082 and A6060 aluminium wrought alloys was investigated, in terms of the strain rate sensitivity on alloy conditions by heat treatment and bake hardenability on pre-strain prior to strain ageing. The tensile test was carried out in a range of strain rate of 4.17 × 10^-5 s^-1 ~ 4.17 × 10^-5 s^-1 in room temperature and the nominal range of pre-strain was 3.0 ~ 10.5%. The tensile deformation of A5082 alloys is characterized as typical case of dynamic strain ageing with negative strain rate sensitivity for all conditions, and the tensile strength indicates a similar level regardless of alloy conditions, except only in full annealed condition. The stress-relief annealing on A6060 alloys can induce practical decrease in strength level of over approximately 100 MPa without any ductility loss, compared to as-rolled condition, while a full annealed and aged condition leads remarkable strengthening effect with the decrease of tensile elongation. Additionally, the bake hardenability of A5082 alloy by strain ageing indicates a negative dependence upon the increase of pre-strain, while A6060 alloy exhibits a positive sign even in low level relatively compared with conventional SPCC.

• Journal of the Korean Wood Science and Technology
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• v.34 no.3
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• pp.30-37
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• 2006

The present study examined the formaldehyde (HCOH) emission characteristic of various wood-based panel used in interior design, and measured changes in formaldehyde emission when a number of VOC reduction methods were applied. Formaldehyde emission showed a clear tendency of increase with the rise of temperature, and the concentration of formaldehyde emitted changed according to the preprocessing condition before measuring. Formaldehyde emission from wood board after bake out treatment was lower than that of the control group. When specimens were coated with urethane, cashew, water, oil stain, they generally showed the decrease of formaldehyde emission, although varying according to finishing material, and when edge sealing was applied the decrease became significant. $TiO_2$ coating was more effective in decreasing formaldehyde under ultraviolet lamps than under ordinary lamps. When the irradiation of ultraviolet lamps gets longer, formaldehyde emission decreased.