Natural Aging in Heat-Treated Medium-Density Fiberboard Panels

2014 ◽  
Vol 634 ◽  
pp. 473-478
Author(s):  
Stefânia Lima Oliveira ◽  
Rafael Farinassi Mendes ◽  
Ticyane Pereira Freire ◽  
Lourival Marin Mendes
Keyword(s):  
Heat Treatment ◽  
Bending Strength ◽  
Treatment Time ◽  
Medium Density Fiberboard ◽  
Natural Aging ◽  
Modulus Of Rupture ◽  
Control Treatment ◽  
Medium Density ◽  
Promising Alternative ◽  
Heat Treated

Heat treatment of wood is a promising alternative in improving its dimensional stability. The action of heat ensures the good quality of the treated wood product, with better performance in environments with high humidity. To prove the positive effect of this treatment, a test in which the specimens are weathered for a certain period of time termed as natural aging was performed. The aim of this study was to evaluate the effect of aging on heat-treated medium-density fiberboard (MDF) panels. Commercial MDF panels produced with pinewood adhesive and urea-formaldehyde were used. The experiment included seven test treatments [at 200, 225, and 250°C heat temperatures for 5 and 10 min] and a control treatment (without heat treatment). The products subjected to these treatments were weathered for 40 days, and climatological data were monitored daily. The results suggested that: 1) There is a decreasing trend in density with increasing time and temperature; 2) the treatment time and temperature had no effect on the ownership of the static bending for modulus of elasticity (MOE); 3) the time period is correlated with the treatment temperature for modulus of rupture (MOR) property; and 4) the thermal treatment of MDF panels did not allow the maintenance of the properties of MOR and MOE static bending strength after natural aging.

Effect of calcite addition on technical properties and reduction of formaldehyde emissions of medium density fiberboard

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3718-3733
Author(s):  
Osman Camlibel
Keyword(s):  
Liquid Paraffin ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Formaldehyde Emission ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Wood Fibers ◽  
Hot Press ◽  
Ammonium Sulphate Solution ◽  
Hot Press Process

Physical, mechanical, and formaldehyde emission properties were studied for medium density fiberboard (MDF) produced with oak (75%) and pine (25%) fibers that had been mechanically refined in the presence of calcite particles. The calcite slurry was prepared at two levels of solids, 1.5% and 3% (10 and 20 kg·m-³). Chips were cooked for 4 min at 185 °C, under 8 bar vapor pressure in an Andritz defibrillator. 1.8% liquid paraffin, 0.72% ammonium sulphate solution, and 11% urea-formaldehyde were added by percentage based on oven-dried wood fibers in the blowline at the exit of the defibrator. The fibers were dried to 11% moisture content. MDF boards (2100 mm × 2800 mm × 18 mm) were created using a continuous hot-press process. The addition of calcite in the course of MDF production resulted in improved physical properties, such as thickness swelling (ThS 24 hours) and water absorption (WA 24 hours). MDF boards prepared with calcite exhibited higher internal bond (IB), modulus of rupture (MOR), and modulus of elasticity (MOE). Resistance to axial withdrawal of screw also was increased by addition of 3% calcite. In addition, the lowest levels of formaldehyde emission were observed for MDF prepared with calcite at the 3% level.

Experiment Investigation for Design on the Sensitization-Dependent Passivation Characteristics of AL-6XN in 3.5% NaCl Solution

2021 ◽  
Vol 21 (7) ◽  
pp. 3984-3988
Author(s):  
Kwang-Hu Jung ◽  
Seong-Jong Kim
Keyword(s):  
Heat Treatment ◽  
Potentiodynamic Polarization ◽  
Treatment Time ◽  
Test Methods ◽  
Double Loop ◽  
Nacl Solution ◽  
Heat Treated ◽  
Cyclic Potentiodynamic Polarization ◽  
Degree Of Sensitization ◽  
Characteristic Values

The sensitization and passivation characteristics of AL-6XN heat-treated for up to 24 h at 800 °C were evaluated through double loop electrochemical potentiodynamic reactivation (2 M H2SO4 + 0.01 M KSCN +2 M NaCl solution) and cyclic potentiodynamic polarization (3.5% NaCl solution) test methods. Furthermore, the dependence between the characteristic values (Epit, Erep, and degree of sensitization) was discussed. The σ phase was precipitated at the intergranular and intragranular in AL-6XN at 800 °C. When the heat treatment time exceeded 1 hour, AL-6XN occurred rapid sensitization due to the precipitation of σ phase. In a 3.5% NaCl solution, the passivation characteristics of AL-6XN with sensitivity were very poor and depended much on the degree of sensitization.

Effects of Heat-Treatment Temperature on the Properties of Negative CTE Eucryptite Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 123-125 ◽  
Author(s):  
Yong Li ◽  
Qi Hong Wei ◽  
Ling Li ◽  
Chong Hai Wang ◽  
Xiao Li Zhang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Heat Treatment Temperature ◽  
Bending Strength ◽  
Sol Gel ◽  
Negative Thermal Expansion ◽  
Treatment Temperature ◽  
Heat Treated

In this paper, negative thermal expansion coefficient eucryptite powders were prepared by sol-gel method using silica-sol as starting material. The raw blocks were obtained by dry pressing process after the powder was synthesized, and then the raw blocks were heat-treated at 600º, 1150º, 1280º, 1380º, 1420º and 1450°C, respectively. Variations of density, porosity and thermal expansion coefficient at different heat treatment temperatures were investigated. Phase transformation and fracture surface morphology of eucryptite heat-treated at different temperatures, respectively, were observed by XRD and SEM. The results indicate that, with the increasing heat- treatment temperature, the grain size and the bending strength increased, porosity decreased, thermal expansion coefficient decreased continuously. Negative thermal expansion coefficient of -5.3162×10-6~-7.4413×10-6 (0~800°C) was obtained. But when the heat-treatment temperature was more than 1420°C, porosity began to increase, bending strength began to decrease, which were the symbols of over-burning, while the main crystal phase didn’t change.

The Stability of γ ’-Co3(Al,W) Phase in Co-Al-W Ternary System

2010 ◽  
Vol 654-656 ◽  
pp. 448-451 ◽  
Author(s):  
Yuki Tsukamoto ◽  
Satoru Kobayashi ◽  
Takayuki Takasugi
Keyword(s):  
Heat Treatment ◽  
Ternary System ◽  
Microstructural Evolution ◽  
Treatment Time ◽  
Bulk Alloy ◽  
Epma Analysis ◽  
Heat Treated ◽  
Cold Rolled ◽  
The Stability ◽  
Couple Method

The thermodynamic stability ’- Co3(Al,W) phase (L12) in the Co-Al-W ternary system at 900 °C was investigated through microstructure and EPMA analysis on a heat-treated bulk alloy. To promote microstructural evolution, the bulk alloy was cold rolled before heat treatment. By heating at 900 °C, the ’ phase was formed discontinuously in contact with the -Co (A1) phase. With increasing heat treatment time, however, the fraction of ’ phase decreased while that of , CoAl (B2) and Co3W (D019) phases increased. These results are consistent with our previous work with a diffusion-couple method, indicating that the ’ phase is metastable, and the three phases of, CoAl and Co3W are thermodynamically stable at 900 °C.

Combined treatment of green pitch pine wood by heat and superheated steam and the effects on physical properties of the products

Holzforschung ◽  
2014 ◽  
Vol 68 (3) ◽  
pp. 327-335 ◽  
Author(s):  
Yonggun Park ◽  
Chang-Deuk Eom ◽  
Yeonjung Han ◽  
Jun-Ho Park ◽  
Yoon-Seong Chang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Physical Properties ◽  
Large Scale ◽  
Superheated Steam ◽  
Bending Strength ◽  
Combined Treatment ◽  
Decay Resistance ◽  
Green Wood ◽  
Heat Treated ◽  
Pitch Pine

Abstract Pitch pine (P. rigida) wood was treated with superheated steam (SHS) and the subsequent effects due to drying and heat treatment (HT) were observed. The following treatment parameters were tested: 180°C air HT, 220°C air HT, 0.1 MPa–180°C SHS HT, 0.1 MPa–220°C SHS HT, 0.5 MPa–180°C SHS HT, and 0.5 MPa–220°C SHS HT. No drying checks were observed in the specimens (500×150×50 mm3) treated at 0.5 MPa–220°C SHS and with these treatment parameters, equilibrium moisture content (EMC) was the lowest. Low EMC has an effect on physical properties such as shrinkage, compressive strength parallel to the grain, bending strength, hardness, and decay resistance. Based on the results, it is expected that the green wood in a large scale is possible to be simultaneously dried and heat-treated without occurrence of checks by the SHS HT process.

Effect of Heat Treatment on the Reactivity and Crystallinity of Coal-Char

2005 ◽  
Author(s):  
Shouyu Zhang ◽  
Junfu Lu ◽  
Jianmin Zhang ◽  
Qing Liu ◽  
Guangxi Yue
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Treatment Time ◽  
Treatment Temperature ◽  
Coal Char ◽  
Heat Treatment Time ◽  
Heat Treat ◽  
Heat Treated ◽  
Layer Stacking ◽  
Crystalline Growth

The effect of heat treatment on the reactivity and crystallinity of char prepared from the vitrinite of two coals (YX, JJ) was investigated by using XRD and TGA in this paper. The results from TGA show that the reactivity of the chars from YXV and JJV decreases with the increase of heat treatment temperature. The reactivity of YXV char decreases quickly and significantly as heat treatment time increases. However, after heat treatment time of 60 min, it decreases slowly. The effect of heat treatment time on the reactivity of JJV char is small. The results from XRD show that the crystallinity of coal-char is determined by the intensity of heat treatment. When heat treatment time is more than 60 minutes, the turbostratic crystallite of YXV char prepared under 900°C changes remarkably and becomes more orderly. The aromatic layer stacking heights (Lc) of YXV Char when heat treated above 900°C increased with the increase of heat treatment time. The effect of heat treat time on Lc of JJV char is small, but under heat treatment temperature of 1200°C, the crystalline of JJV char grows distinctly. There is a good parallel relationship between the crystalline growth and deactivation of the chars. It can be concluded that the growth of the crystalline is the main reason for the deactivation of coal-char.

The Effect of Incomplete Solution Treatment on the Tensile Behavior and Mechanical Anisotropy of 2195 Aluminum Lithium Alloy

2019 ◽  
Vol 22 ◽  
pp. 109-117
Author(s):  
Wesley Walker ◽  
Rudolf Marloth ◽  
Ye Thura Hein ◽  
Omar S. Es-Said
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Cold Work ◽  
Rolling Direction ◽  
Solution Treatment ◽  
Tensile Behavior ◽  
Mechanical Anisotropy ◽  
Aluminum Lithium Alloy ◽  
Heat Treated ◽  
Aluminum Lithium

This study aimed to characterize the effects of incomplete solution treatment time on the tensile behavior of 2195 Al-Li alloy. Two sets of plates of 2195 Al-Li alloy received solution heat treatment. One set received the prescribed treatment, held in the furnace for 30 minutes after the material had reached 507°C. The other set was in the furnace for only 30 minutes and did not reach 507°C until after about 15 to 20 minutes. Both set of plates were water quenched. Samples from the plates were then stretched 2.5-3% or 6%, rolled 6%, and rolled 24%, at 0°, 45°, and 90° relative to the rolling direction of the as-received material. The samples were aged at 143°C for 36 hours and air-cooled. Tensile specimens were milled out at 0°, 45°, and 90° relative to the original rolling direction. Tensile testing was performed on all samples. The incomplete heat treatment (incomplete solution treatment) resulted in a significant reduction in strength. This was probably due to the formation of fewer T1 precipitates after aging, thereby reducing the amount which could nucleate during cold work. The fully heat treated samples had higher percent yield strength, ultimate strength, and elongation.

Effect of heat treatment time on cycle performance of LiMn2O4 with “Nano Inclusion” for lithium ion batteries

RSC Advances ◽  
2015 ◽  
Vol 5 (53) ◽  
pp. 42455-42460 ◽  
Author(s):  
Shogo Esaki ◽  
Motoaki Nishijima ◽  
Shigeomi Takai ◽  
Takeshi Yao
Keyword(s):  
Heat Treatment ◽  
Lithium Ion Batteries ◽  
Discharge Capacity ◽  
Treatment Time ◽  
Lithium Ion ◽  
Heat Treatment Time ◽  
Cycle Performance ◽  
Heat Treated

The cycle performance of LiMn2O4 with “Nano Inclusions” is higher than that of LiMn2O4 without “Nano Inclusions” and the discharge capacity of LiMn2O4 with “Nano Inclusions” heat-treated for 4 h surpassed that of LiMn2O4 without it at over 31 cycles.

Effect of Heat Treatment on Decay Resistance of Chinese Fir and Pine

2012 ◽  
Vol 468-471 ◽  
pp. 1118-1122
Author(s):  
Yan Jun Li ◽  
Lan Xing Du ◽  
Gou Ying Hu ◽  
Xing Xia Ma
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Treatment Time ◽  
Brown Rot ◽  
Decay Resistance ◽  
Chinese Fir ◽  
Heat Treatment Time ◽  
White Rot ◽  
Heat Treated ◽  
Brown Rot Fungus

To enhance decay resistance, the effect of heat treatment and the variation of chemical composition on Chinese Fir and Pine were investigated in this study — heat treatment temperature was 170°C, 190°C and 210°C, respectively, heat treatment time was 2, 3 and 4hours, respectively. Both of them were subsequently exposed to white-rot fungus and brown-rot fungus. The results showed that:(1) With the increasing of the heat treatment, decay resistance of Chinese Fir and Pine were improved, anti-corrosion of Pine after being heat treated at 190°C which were exposed to write-rot fungus can reach I, anti-corrosion of Chinese Fir after being heat treated at 170°C treated which were exposed to brown-rot fungus could reach I yet, After being heat treated at 210°C for 3 hours , the Chinese fir samples had no measurable weight loss when exposed to the write-rot fungus.(2) There was no remarkable influence on both Chinese Fir and Pine by heat treatment time.(3) The moisture content of Chinese Fir and Pine were lower than the moisture content that the rot fungus need, macromolecule chains such as cellulose and hemicellulose broke down, their contents decreased, and the hemicellulose decomposed into acetic acid, they prevented the growth of rot fungus.

Effect of juvenile wood on strength properties and dimensional stability of black spruce medium-density fiberboard panels

Holzforschung ◽  
2005 ◽  
Vol 59 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jun Li Shi ◽  
Shu Yin Zhang ◽  
Bernard Riedl
Keyword(s):  
Water Absorption ◽  
Dimensional Stability ◽  
Juvenile Wood ◽  
Black Spruce ◽  
Medium Density Fiberboard ◽  
Strength Properties ◽  
Analysis Of Covariance ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Mean Values

Abstract Strength properties and dimensional stability of medium-density fiberboard (MDF) panels made from black spruce (Picea mariana [Mill.] BSP.) 0–20, 21–40, and over 40 year old fiber were studied. An analysis of covariance (ANCOVA) was performed to examine the differences in modulus of rupture (MOR), modulus of elasticity (MOE), and thickness swell (TS) of the three types of panels, while panel density was treated as a covariate in order to adjust the mean values that were partly attributed to panel density. The results indicate that MOR, internal bond (IB), and water absorption of MDF panels made from 0–20 year old fiber, which contained 100% juvenile wood, were significantly superior to those of panels made from 21–40 and over 40 year old fiber; but linear expansion (LE) of MDF panels made from 0–20 year old fiber was significantly larger than that of panels from the other two age classes. The differences in MOR, IB, water absorption, and LE between panels made from 21–40 and over 40 year old fiber were not significant. The comparisons of panel MOE and TS were relatively dependent on panel density due to existence of interactions among the three age groups.

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