• 한국기계연구소 소보
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• 통권18호
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• pp.163-168
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• 1988

Impregnation of molten thermoplastic resin into continuous unidirectional fiber bundles was investigated. The degree of impregnation is defined as the ratio between the number of impregnated fibers and the total number of fibers of a bundle. The degree of impregnation was modeled as a function of time, impregnation pressure, temperature and tow size assuming the radial inward flow through the fiber bundle is governed by the Darcy's law. The permeability was assumed to be constant. Experiments were performed to evaluate the validity of the medel. Today's T300 graphite fiber bundles and Polyetheretherketone(PEEK) resin was used. A fiber bundle and resin powder were put into a mold and pressure and temperature were applied. After a predetermined time, the sample was taken out and microphotographs of the cross-section were taken. From the microphotographs, the number of impregnated fibers was counted and then the degree of impregnation was determined. Experiments were also performed for different tow sizes. Good agreements were found between the model and the experiments rendering a confidence in the model.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.105-110
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• 2013

A repeated impregnation and carbonization process was performed to prepare high-density woodceramics using MDF. The physical properties were estimated to further confirm morphologically structurally occurred changes of one-time and two-time phenolic resin treated and carbonized woodceramics. As compare one-time and two-time carbonized woodceramics, the increasing rate of weight and density declined after second carbonization as the resin impregnation ratio grew higher, and when the resin impregnation ratio was 40 percent, the weight and density of the second carbonization increased more than in the first step by 20.5% and 33.9% respectively which were the highest rates.

• 한국정밀공학회지
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• 제20권7호
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• pp.78-83
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• 2003

Characterization of an ultra precision grinding plate for GMR head manufacturing is performed by measuring frictional forces between the grinding plate and the advanced ceramic Two kinds of methods of producing the precision grinding plates are presented: texturing and micro-channeling. Texturing is effective in terms of production time but micro-channeling excels in quality control. It is found that the frictional coefficient of a precision grinding plate decreases as the impregnation of diamond grain onto the precision-grinding plate progresses, and remains unchanged once the impregnation process is successfully completed, even after 100 revolutions of the precision-grinding plate against the advanced ceramic under 40 N of normal force. Therefore, the measurement of the frictional coefficient can replace costly and time-consuming process of estimating the level of impregnation of diamond grain on the precision-grinding plate, which has been performed by using scanning electron microscope, and be employed as an index to determine the level of impregnation of diamond grain.

• Journal of the Korean Wood Science and Technology
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• 제39권1호
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• pp.60-67
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• 2011

본 연구에서는 고밀도 우드세라믹을 제조하기 위한 기초 연구로서 수지함침율 및 탄화온도에 따라 제조된 1차 탄화 우드세라믹을 수지 재 함침 후 2차 탄화하여 우드세라믹을 제조하고 밀도경사를 조사하였다. 2차 탄화 후 최소, 평균 및 최고밀도가 1차 탄화 우드세라믹보다 증가하였고, 밀도경사 비율도 증가하였다. 따라서 고밀도와 밀도경사 비율이 작은 균질한 우드세라믹을 제조하기 위해서는 2차 함침과 2차 탄화에 의한 우드세라믹 제조방법도 효과가 있는 것으로 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제48권5호
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• pp.722-731
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• 2020

The purpose of this research is to determine the efficiency of impregnation using phenol formaldehyde resin to enhance Falcataria wood's stability and better mechanical properties. Impregnation process was carried out after moisture content stabilized at 12% on samples with a dimension of 20 mm × 20 mm × 300 mm at various concentrations and pressure time. Dimensional stability was evaluated by thickness swelling (TS) and anti-swelling efficiency (ASE) and the young's modulus was conducted according to BS 573. The mechanical properties and dimensional stability of impregnated wood were evaluated. Dimensional stability and mechanical properties of Falcataria wood were successfully increased after impregnation. PF impregnation can improve the mechanical properties and the density from 0.26 g/㎤ to 0.30 g/㎤ even with only 10% of weight percent grain. Dimensional stability increases with increasing resin concentration and time pressure. The highest increase in mechanical properties was found at a higher concentration of PF. The penetration of PF into the wood's cell darkens the color of impregnated wood.

• Design & Manufacturing
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• 제15권3호
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• pp.39-44
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• 2021

In molding of continuous fiber-reinforced thermoplastic composites, it is very difficult to impregnate between the reinforcements and the matrix since the matrix has a high melting temperature and high viscosity. Therefore, most of composite molding processes are divided in the manufacturing processes of intermediate materials called prepreg and the forming of products from intermediate materials. The divided process requires additional facilities and thermoforming, and they increase the cycle time and cost of composite products. These problems can be resolved by combining the continuous fiber-reinforced composite molding process with injection molding. However, when a composite material is manufactured by inserting woven fabric into the injection mold, poor impregnation occurs on the surface of the molded product. It affects the properties of the composites. In this paper, through an impregnation experiment using cores with different heat transfer rates and pore densities, the reason for the poor impregnation was confirmed, and molding experiments were conducted to produce composite with improved surface impregnation by inserting the mesh. And also, the surface impregnation and deformation of composites molded using different types of mesh were compared with each other.

• Journal of the Korean Wood Science and Technology
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• 제43권3호
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• pp.327-333
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• 2015

진공가압 수지함침 처리에 의한 목재의 치수안정화 정도를 측정하기 위하여 침엽수 3수종에 수용성 멜라민 수지를 수지농도와 처리시간별로 처리한 후, 수지함침 열압축목재(compreg)를 제조한 다음 치수안정성 개선효과를 검토하였다. 수지농도가 높고 처리시간이 길수록 용적 수축률과 항용적 팽윤율은 증가하였으나, 용적 팽윤율, 항용적 수축률 및 흡수성은 감소하였다. 또한 중량 증가율은 수지의 농도가 높을수록 현저히 증가하였으나 처리시간과는 일정한 관계가 없었다.

• Journal of the Korean Wood Science and Technology
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• 제48권4호
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• pp.417-430
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• 2020

4종의 판상형 목재제품의 방염제 도포량과 침지시간에 따른 방염성능을 분석하기 위하여 소방청의 방염성능기준에 따라 목재제품의 탄화길이와 탄화면적을 측정하였다. 잣나무 합판, 낙엽송 합판, 편백 판재, 타공처리된 자작나무 합판에 자체 개발된 방염제를 각각 300, 500 g/㎡씩 도포하고 방염처리되지 않은 시험편과 비교하였다. 일반적으로 방염제의 도포량이 증가함에 따라 탄화길이와 탄화면적이 감소하여 방염성능이 증가하는 경향을 나타냈으나, 낙엽송 합판을 제외하고 탄화길이와 탄화면적의 감소량이 크지 않았다. 타공처리된 자작나무 합판의 침지시간에 따른 방염성능은 60분의 침지시간까지 양의 상관관계를 나타냈으나, 그 이후 점차 완만해지는 경향을 보였다. 방염제의 도포량과 침지시간에 따른 목재제품의 방염성능은 추후 방염성능 기준에 맞는 불연·준불연 목재의 생산을 위한 기초자료로 이용될 것으로 기대된다.

• 한국세라믹학회지
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• 제49권5호
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• pp.454-460
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• 2012

The nano-sized zirconia powders were synthesized in an impregnation method using pulp and $ZrOCl_2{\cdot}8H_2O$ as an initial material. The synthesized powders were characterized by XRD and FE-SEM. The particle size of the powder was controlled by preparation conditions, such as drying temperature and time. As a result of the various drying and calcination conditions, 30~50 nm sized homogeneous zirconia particles were obtained at $800^{\circ}C$ for 1 h. Crystallization and the rapid growth of particles were accelerated with increasing calcination temperature and time. Tetragonal phase generated below $800^{\circ}C$ were transferred to monoclinic phase with increasing calcination temperature and time. Moreover, above $800^{\circ}C$, heat treatment time had very large influence on the particle growth, and the change of drying condition also had large influence on the growth of a crystal.

• 한국세라믹학회지
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• 제26권6호
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• pp.729-736
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• 1989

This study aims to reinforce concrete structure by impregnation of molten sulfur. The improved properties of sulfur impregnated concerete were confirmed by compressive strength test and water proof effect. Following variables were adopted to evaluate impregnation parameters ; 1) the effect of water content in concrete structure (0-8%) 2) impregnation time of molten sulfur(0-22hr) 3) impregnation temprature of molten sulfur(13$0^{\circ}C$, 14$0^{\circ}C$). In partial ponding experiments, the concrete specimen of sulfur impregnated by 2wt% yields 1.5 times higher value of compressive strength than that of control one(non-impregnated concerte). In complete ponding experiments, the mortar specimen of slufur impregnated by 12-14wt% yields 2-3 times higher value of compressive strength than that of control one (non-impregnated mortar). From the examination of X-ray diffractions, $\alpha$-sulfur was found in concrete pores. Homogeneous impregation of molten sulfur into concrete pores was also identified with poresize analysis and micrographs of SEM.