• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.602-618
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• 1996

The purpose of this study was to investigate the effect of acid treatment of fluoride applied dentin surface with various concentrations of phosphoric acid for various periods of time on dentin bonding. Dentin specimens prepared from freshly extracted bovine mandibular anterior teeth were divided into fluoridated and nonfluoridated groups. Specimens of nonfluoridated group were pretreated with 10% phosphoric acid for 15 seconds. Those of fluoridated groups were treated with 2% sodium fluoride or 2% stannous fluoride solution for 5 minutes and stored in $37^{\circ}C$ distilled water for 3 days, followed by phosphoric acid treatment. The concentrations of phosphoric acid were 10%, 32% or 50% and the treatment periods of time were 15, 30 or 60 seconds. All the specimens were bonded with All Bond$^{(R)}$ 2 and Bisfil$^{TM}$ composite resin. After bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, tensile bond strengths of each specimens were measured and the pretreated dentin and the fractured dentin surfaces were examined under the scanning electron microscope. The results were as follows : The tensile bond strengths from the fluoridated groups were significantly lower than those from the nonfluoridated group when the concentrations of phosphoric acid and the treatment periods of time were equal in all the groups (p<0.05). In general, the higher the concentration of phosphoric acid and the longer the treatment period of time for acid etching on the fluoride applied dentin surface, the higher were the bond strength values. Recovery of bond strength of the dentin bonding agent was better in the NaF applied group than in the $SnF_2$ applied one. SEM findings of NaF applied and $SnF_2$ applied dentin surfaces demonstrated reaction product-covered and partially or completely obstructed dentinal tubules. SEM findings of dentin surfaces fluoridated for 5 minutes followed by etching showed wider tubular openings and more clean dentin surfaces when dentin was etched with higher concentration of phosphoric acid for longer period of time. On the SEM observations of the fractured dentin-resin interface, the etched specimens of fluoridated group showed an adhesive failure mode when the concentration of phosphoric acid and the treatment period of time were same as in the nonfluoridated group. As the concentration of phosphoric acid and the treatment period of time increase during acid etching, the cohesive failure area increased. However, excessive acid etching caused adhesive failure.

• 한국결정성장학회지
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• 제16권3호
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• pp.106-111
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• 2006

The objective of this paper is to compare the surface features of two kinds of nano-porous activated carbon fiber (NPACF) treated with potassium and the variation of their properties by phosphoric acid pre-treatment. X-ray diffraction (XRD) patterns indicate that NPACF containing potassium species show better performance for potassium and potassium salts by pre-treatment with phosphoric acid. In order to present the causes of the differences in surface properties and specific surface area after the samples were treated with phosphoric acid, pore structure and surface morphology are investigated by adsorption analysis and SEM. For the chemical composition microanalysis for potassium loading of the NPACF pre-treated with phosphoric acid, samples were analyzed by EDX. Finally, the type and quality of oxygen groups are determined from the method proposed by Boehm.

• 접착 및 계면
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• 제5권3호
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• pp.10-17
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• 2004

본 연구에서는 레이온직물에 대하여 승온속도, 안정화온도, 분위기가스, 화학적 표면처리 등 여러가지 조건에서 안정화공정을 행한 후, 직물의 열수축과 열안정성, 그리고 미세구조에 미치는 공정 조건의 영향을 조사하였다. 레이온직물의 열수축과 중량변화에 인산처리 유무와 승온속도가 가장 중요한 영향을 미쳤다. 특히, 인산처리를 한 경우가 하지 않은 경우보다 레이온직물의 두께변화는 약 80%, 길이변화는 약 20%, 그리고 중량변화는 약 26%가 줄어드는 열수축 억제 효과를 보여주었다. 안정화 된 레이온직물의 열안정성에는 안정화온도와 인산처리 그리고 분위기가스와 승온속도 등 주어진 안정화공정 조건 모두가 영향을 주었다. 또한 안정화섬유의 표면 상태 및 섬유직경 변화도 공정 전에 행한 인산처리의 유무에 의존하였다.

• Geomechanics and Engineering
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• 제15권6호
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• pp.1135-1141
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• 2018

Volume changes of soils induced by inorganic acids cause severe foundation and superstructure failures in industrial buildings. This study aimed to assess the potential of fly ash to control volume changes in soils under acidic environment. Two soils such as black cotton soil predominant with montmorillonite and kaolin clay predominant with kaolinite were used for the present investigation. Both soils exhibited an increase in swelling subjected to phosphoric acid contamination. Ion exchange reactions and mineralogical transformations lead to an increase in swelling and a decrease in compressibility in black cotton soil, whereas phosphate adsorption and mineral dissolution lead to an increase in swelling and compressibility in case of kaolin clay. Different percentages of Class F fly ash obtained from Ramagundam national thermal power station were used for soil treatment. Fly ash treatment leads to significant reduction in swelling and compressibility, which is attributed to the formation of aluminum phosphate cements in the presence of phosphoric acid.

• 폴리머
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• 제37권2호
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• pp.196-203
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• 2013

Surface modification of meta-aramid fibers was performed by phosphoric acid treatment. Surface morphology and element composition of untreated and treated fibers were analyzed by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Effects of surface modification on the mechanical strength of aramid papers made from meta-aramid fibers and fibrid were investigated. Surface modification conditions were optimized by response surface analysis (RSA). Results show that phosphoric acid treatment increases the surface roughness and oxygen content of aramid fibers. They improve the interface bonding strength between aramid fibers and fibrid, which improves the tensile strength of aramid papers. The results of response surface analysis indicate that the tensile strength of aramid papers increases by 47.5% and reaches the maximum when meta-aramid fibers are treated with 21.1wt% phosphoric acid solution at $39.3^{\circ}C$ for 36.7 min.

• 한국세라믹학회지
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• 제18권3호
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• pp.192-200
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• 1981

This study deals with the low temperature ($25^{\circ}C$-$600^{\circ}C$) properties of Kaolin-Phosphate-water systems. Phosphoric acid, mono aluminum phosphate, mono ammonium phosphate, the mixture of phosphoric acid and mono aluminum phosphate, and the mixture of phosphoric acid and mono ammonium phosphate were used to characterize the M.O.R. of the systems with to quantity of phosphates, curing time, and firing temperature. Firing shrinkage, viscosity, surface tension, DTA, TGA, and X-ray diffraction patterns were also measured in order to investigated the factors of strengthening. The results of this study were summarized as follows: 1. The M.O.R. of kaolin-phosphate systems were stronger than that of Kaolin-water system at room temperature or low temperature($25^{\circ}C$-$600^{\circ}C$). Though it was increased according to the longer curing time, the higher temperature, and the more addition of phosphate, the M.O.R. were decreased in the case of 10 wt% phosphate addition in the system of phosphoric acid, mono aluminum phosphate and phosphoric acid-mono aluminum phosphate. 2. When the concentration of Phosphate was at 4 wt%, the M.O.R. of specimen cured at $25^{\circ}C$ and added to the phosphoric acid was strongest among the specimens in added to the others phosphates. Whereas, when the concentration of phosphate was above 6wt%, the M.O.R. of specimen cured at $25^{\circ}C$ and added to the phosphoric acid mono ammonium phosphate system cured at $25^{\circ}C$ was the strongest. 3. The M.O.R. of the specimen heated, in the temperature range of 15$0^{\circ}C$-1$600^{\circ}C$, and added to the mixture of phosphoric acid-mono aluminum phosphate system or phosphoric acid-mono ammonium phosphate system was stronger than that of specimen added to Phosphoric acid, mono-aluminum Phosphate or mono-ammonium phosphate alone. 4. The bonding force of phosphate binders was more closely related to surface tension than viscosity and it tended to be inversely proportional to surface tension. The bonding force after heating treatment seemed to be caused by the change of structure of phosphate according to heating.

• 분석과학
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• 제18권4호
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• pp.355-361
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• 2005

본 연구는 인산의 전처리에 의한 두 종류의 활성탄소섬유의 특성 변화와 여기에 칼륨을 처리하여 표면 특성을 비교하고자 하였다. X-선 회절 패턴은 인산을 전처리함에 따라 칼륨종을 포함하는 활성탄소섬유에 대한 금속과 금속염의 존재에 대한 좋은 결과를 나타내었다. 인산을 처리한 후에 표면특성과 비표면적 변화에 차이의 원인을 나타내기 위하여, 동공구조와 표면 모폴로지를 흡착분석과 SEM에 의하여 연구하였다. 인산을 가지고 전처리한 활성탄소섬유의 칼륨 처리효과에 대한 화학적 구성에 대한 원소분석을 위하여 EDX를 사용하였다. 최종적으로, 산소를 포함하는 기능기의 형태와 정성분석은 Boehm에 의하여 제안된 방법으로 부터 결정하였다.

• 한국환경복원기술학회지
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• 제14권6호
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• pp.17-27
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• 2011

Prunus serrulata var. serrulata f. spontanea (E. H. Wilson) C. S. Chang was treated with dried swine excrement at various concentration levels, and their growth reactions and the contents of total kjeldahl nitrogen and total phosphoric acid were analyzed. The result is as follows; 1. When the plants were treated with 0.25% of dried swine excrement, the seed germination rate of Prunus serrulata var. serrulata f. spontanea was higher than that of the control. However, it showed a tendency to decrease when the treatment concentration got higher than 0.25%. 2. The growth rate of species was highest when they were treated with 0.25% of dried swine excrement. It tended to decrease with higher treatment concentration than 0.25%. Significant difference was clear between the control and the experimental plants of Prunus serrulata var. serrulata f. spontanea. 3. The contents of nitrogen and phosphoric acid in Prunus serrulata var. serrulata f. spontanea also got higher as the concentration of dried swine excrement increased. However, the content of total kjeldahl nitrogen was highest in the leaves, and followed by the roots and stems. In contrast, the content of total phosphoric acid were highest in the roots, and followed by the leaves and stems. Therefore, stems had the lowest contents of both nitrogen and phosphoric acid. 4. The contents of total kjeldahl nitrogen and total phosphoric acid in the soil were measured before and after the growth experiment of Prunus serrulata var. serrulata f. spontanea treated with dried swine excrement. The contents of nitrogen and phosphoric acid significantly decreased after the experiment. In conclusion, the contents of total kjeldahl nitrogen and total phosphoric acid accumulated in the plants increased as the concentration level of dried swine excrement got higher. The seed germination and plant growth rates were best at 0.25% treatment of dried swine excrement. The treatment of dried swine excrement may bring high effects on increasing the plant growth rate but could damage the plants with higher concentration than they need. Different optimal concentration levels of dried swine excrement for different plants should be found before it is used as fertilizer.

• 멤브레인
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• 제24권1호
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• pp.50-62
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• 2014

상 전이 공정을 이용하여 polysulfone계 비대칭 정밀 여과막을 제조하였다. Polysulfone/N-methyl-2-pyrrolidone/polyvinylpyrrolidone/phosphoric acid계로 이루어진 casting 용액을 사용하였으며 응고조로는 물을 사용하였다. 멤브레인 제조공정에 적용된 상 전이 공정으로 증기 유도 상 전이 공정을 적용하였으며 상대습도 74%에서 캐스팅 판의 온도와 노출 시간을 조절한 결과 기공의 크기와 구조에 있어 변화를 관찰할 수 있었다. 제조된 멤브레인의 구조는 SEM과 microflow permporometer를 사용하여 조사하였다. Phosphoric acid의 첨가는 조밀한 스펀지 형태의 멤브레인을 느슨한 스펀지 형태의 멤브레인으로 변화시켰으며 촉매량의 Phosphoric acid 첨가로도 평균 기공크기는 거의 $0.2{\mu}m$ 정도 커지고 유량도 약 3,000 LMH가 증가하였다. 캐스팅 판의 온도와 노출 시간의 변화는 표면층의 구조, 기공의 크기 및 공극률에 큰 변화를 가져옴을 확인할 수 있었다.

• 한국유기농업학회지
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• 제9권3호
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• pp.103-117
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• 2001

This study was inducted to investigate the effects of microbial fertilizers on the fields of young radish(Raphanus sativus L.), chemical components of plant and soil, and the microbial floras. Six microbial fertilizers, MPK+Husk+Palma, Husk+Palma, MPK+Compost, Compost, BIO Livestock Clean System(BLCS) cattle dropping, and Tomi were used. The yields of young radish were increased in six microbial fertilizer treatments. The fresh matter weight, the number of leaves, and the dry matter weight of young radish in BLCS cattle dropping treatment, the leaf length in MPK+Husk+Palma treatment, the sugar content in Husk+Palma treatment, arid the leaf width in Tomi treatment showed the highest amount, respectively. The effects of microbial fertilizers on chemical characteristics of young radish and soil were examined. Phosphoric acid amount of young radish in Tomi treatment was much higher than other treatments. Potassium amount of young radish showed high significance in all microbial fertilizer treatments compared with control, and shoved the highest in Compost treatment . Two components, phosphoric acid find potassium, in soil inoculated by microbial fertilizers showed significant. Phosphoric acid in the Tomi treatment and Potassium in Husk+Palma treatment were increased. The microorganic populations in soil inoculated with microbial fertilizers were examined. While the number of Bacillus in ceil was increased in MPK+Husk+Palma treatment, the numbers of total bacteria, actinomycetes, and fungi were increased in Tomi treatment.