• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.317-320
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• 2008

The Hot Stamping process, which is the hot pressing of steel parts using cold dies. can utilize both case of shaping and high strength due to the hardening effect of rapid quenching during the pressing. We carried out experiments of quenching rate and tempering treatments at temperatures of $200^{\circ}C$ and $300^{\circ}C$ and different soaking times. Tn this study, the mechanical properties and microstructure of micro boron alloyed steels after heat treatments are compared.

• 한국세라믹학회지
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• 제47권6호
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• pp.485-490
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• 2010

In our previous studies, continuous SiC fiber-reinforced SiC-matrix composites ($SiC_f$/SiC) had been fabricated by two different slurry infiltration methods: vacuum infiltration and electrophoretic deposition (EPD). 12 wt% of $Al_2O_3-Y_2O_3$-MgO with respect to SiC powder was used as additives for liquid-phase assisted sintering. After hot pressing at $1750^{\circ}C$ under 20 MPa for 2 h in Ar atmosphere, a high composite density could be achieved for both cases, whereas the problems such as large grain size and non-uniform distribution of liquid phase were observed, which was resulted in the relatively poor mechanical properties of composites. Therefore, efforts have been made to reduce the grain growth during the sintering, including the optimization for hot pressing condition and utilization of spark plasma sintering using a SiC monolith. Based on the results, spark plasma sintering was found to be effective method in decreasing the amount of sintering additive, time and grain growth, which will be explained in comparison to the results of hot pressing in this paper.

• Journal of the Korean Wood Science and Technology
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• 제25권3호
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• pp.16-23
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• 1997

This study was carried out to discuss feasibility of high density polyethylene(HDPE) as a new substitute for the conventional adhesives in plywood manufacture. Plywood was composed of radiata pine(Pinus radiata) and Malas(Homallium feotidium) veneers and bonded by HDPE. Adhesion characteristics and anatomical scanning has been examined through tensile-shear strength test and scanning electron microscopy(SEM). The results are as follows; 1. Optimum loading quantity was 15g/$(30.3{\times}30.3)cm^2$, and tensile-shear strength increased with the increase of loading quantity. 2. Even at the hot pressing time of 1 minute, tensile-shear strength met the value of KS(over the 7.5kgf/$cm^2$), and tensile-shear strength increased with the increase of hot pressing time. 3. Plywood composed of veneer at moisture content of 19.6% showed similar tensile-shear strength to that at air conditioned moisture content of 11.4%. 4. Under the same condition of hot pressing time, tensile-shear strength of plywood bonded by HDPE met the KS value of boil and wet test and proved the same group as phenol formaldehyde adhesive. 5. HDPE films showed mechanical adhesion through penetration into the lathe check and ray of veneer.

• Macromolecular Research
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• 제17권8호
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• pp.616-622
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• 2009

In-depth understanding of the influence of hot pressing and melt processing on the properties of thermoplastic polyurethane (TPU) is critical for effective mechanical recycling of TPU scraps. Therefore, this study focused on the effects of hot pressing and melt mixing on molecular weight (MW), polydispersity index (PDI), melt index (MI), characteristic IR peaks, hardness, thermal degradation and mechanical properties of TPU. The original TPU pellet (o-TPU) showed two broad peaks at lower and higher MW regions. However, four TPU film samples, TPU-0 prepared only by hot pressing of o-TPU pellet and TPU-1, TPU-2 and TPU-3 obtained by hot pressing of melt mixed TPUs (where the numbers indicate the run number of melt mixing), exhibited only a single peak at higher MW region. The TPU-0 film sample had the highest $M_n$ and the lowest PDI and hardness. The TPU-1 film sample had the highest $M_w$ and tensile modulus. As the run number of melt mixing increased, the peak-intensity of hydrogen bonded C=O stretching increased, however, the free C=O peak intensity, tensile strength/elongation at break and average MW decreased. All the samples showed two stage degradations. The degradation temperatures of TPU-0 sample (359 $^{\circ}C$ and 394 $^{\circ}C$)were higher than those of o-TPU (342 $^{\circ}C$ and 391 $^{\circ}C$). While all the melt mixed samples degraded at almost the same temperature (365 $^{\circ}C$ and 381 $^{\circ}C$). The first round of hot pressing and melt mixing was found to be the critical condition which led to the significant changes of $M_n$/$M_w$/PDI, MI, mechanical property and thermal degradation of TPU.

• Journal of the Korean Wood Science and Technology
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• 제12권2호
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• pp.35-43
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• 1984

This study was carried out to investigate the block shear strength of the 2ply laminated wood composed of Pinus thunbergii with ureaformaldehyde resin as adhesives according to pressure (6, 9, 12, 15kg/$cm^2$), pressing time(5, 10, 20, 30 hrs.), amount of spread(54, 108, 217, 324g/$cm^2$), hardener(10, 20, 30, 40% of 10% $NH_4CL$ on resin) and extender(0, 5, 10, 15% wheat flour on resin), and the bending strength and bending young's modulus of laminated beam according to the number of ply. The results were summarized as follows; 1. According to pressing pressure with amount of spread 217g/$cm^2$ both dry and wet shear strength of laminated wood showed the highest in 15kg/$cm^2$, and hot-cold soaking treatment showed the highest in 9kg/$cm^2$, while all shear strength of dry, wet and hot-cold soaked laminated wood have been reduced with the increasing of pressing time. 2. According to amount of spread, adhesion strength with the dry, wet and hot-cold soaking treatments revealed the highest in 217g/$cm^2$ and have been reduced under or over 217g/$cm^2$ of spread. 3. According to addition of hardener and extender, all shear strength of laminated block with the dry, wet and hot-cold soaking treatments have been reduced in increasing of addition amount of hardener and extender. The bending strength of beam according to the number of ply showed the highest in 2ply laminated wood and horizontal loading beam to glue line had the higher in strength than the vertical loading.

• 소성∙가공
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• 제4권4호
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• pp.398-409
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• 1995

The wear properties of the alumina short fiber reinforced tin-bronze matrix composites manufactured by hot pressing was studied at the room temperature and $350^{\circ}C.$ The wear loss of various specimens having different constituent and different density was examined by a pin-on-disc type wear testing machine. The results were discussed by the observation of the worn surface morphology and the analysis of the composition on the worn surfaces. Since the reinforced effect of the alumina fiber on the wear resistance was dependent on the strength of alloy matrix, the pressureless sintered composites having a lower matrix strength showed a marked increase in wear resistance by the fiber reinforcement. As the wear condition became severe, the fiber reinforcement was more effective. The delamination on the wear surface was observed in the pressureless sintered specimens having pores which are related to the initiation and the propagation of cracks. However, the wear mechanism acting on a big failure area was not found on the wear surfaces of the hot pressed specimens having a few pores.

• 한국재료학회지
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• 제11권12호
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• pp.1068-1073
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• 2001

An n-type iron$silicide(Fe_{0.98}Co_{0.02}Si_2)$has been produced by mechanical alloying process and consolidated by vacuum hot pressing. Although as-milled powders after 120 hours of milling did not show an alloying progress,${\beta}-FeSi_2$phase transformation was induced by isothermal annealing at$830{\circ}C$for 1 hour, and the fully transformed${\beta}-FeSi_2$phase was obtained after 4 hours of annealing. Near fully dense specimen was obtained after vacuum hot pressing at$ 1100{\circ}C$with a stress of 60MPa. However, as-consolidated iron silicides were consisted of untransformed mixture of ${\Alpha}-Fe_2Si_5$and ${\varepsilon-FeSi$phases. Thus, isothermal annealing has been carried out to induce the transformation to a thermoelectric semiconducting${\beta}-FeSi_2$phase. The condition for${\beta}-FeSi_2$transformation was investigated by utilizing DTA, SEM, and XRD analysis. The phase transformation was shown to be taken place by a vacuum isothermal annealing at$830{\circ}C$and the transformation behaviour was investigated as a function of annealing time. The mechanical properties of${\beta}-FeSi_2$materials before and after isothermal annealing were characterized in this study.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.538-543
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• 2008

A roller with a shaft and hot oil paths for pressing electrodes of polymer batteries were modeled and analyzed by FEM. There are many hot oil tubes in the roller and shaft, through which $72^{\circ}C$ hot oil flows for heating the surface of a roller and shaft. Thermal deformations and temperatures distributions of the roller and shaft were calculated and a convection boundary condition on surfaces was used. The influence of existence of a groove in the shaft on the flatness of a roller surface caused by thermal deformation was investigated. In addition, the amount of spring-back of electrodes under vacuum pressure and heating was calculated after the hot rolling process. It was shown from this study that the groove in one shaft had a favorable effect on the surface flatness.

• 한국세라믹학회지
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• 제25권3호
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• pp.268-276
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• 1988

KCI을 사용한 용융염합성법에 의해 침상형$(Pb_{1-x}Ba_x)_{1-y}La_{2y/3}Nb_2O_6$ (PBLN)분말을 합성하고 합성분말의 형상에 미치는 Ba 및 La 치환의 영향을 조사하였다. 또 이 침상형 분말을 사용하여 doctor-blade법 및 hot-press 법에 의해 입자배향 세라믹스를 제작하고 유전적, 압전적, 광학적 성질을 조사하였다. 얻어진 PBLN 분말의 형상 및 입자배향 PBLN 세라믹스의 전기적 특성은 분말합성시의 열처리조건과 Ba 및 La 치환량에 따라 현저히 달랐다. 특히 PBLN 세라믹스의 유전율 및 전기기계결합계수는 입자배향 세라믹스 제작시의 가압방향에 따라 뚜렷한 이방성을 나타내었다.

• Tribology and Lubricants
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• 제24권5호
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• pp.269-274
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• 2008

Carbon nanotube composite is considered to be a good candidate material for composite material because of its excellent mechanical property and low density under high temperature as well as good wear and frictional properties. In this study, tribological characteristics of carbon nanotube aluminum composite were evaluated using pin-on-disk wear tester. Spark Plasma Sintering method is more effective than Hot Pressing method in terms of wear and friction. The composite with 1% CNT has the lowest friction and wear characteristic.