폐유리 잔골재 혼합 시멘트 콘크리트의 혼화재 치환에 따른 열팽창 특성

김유경,이재훈,이재훈,김연태,정진훈 한국도로학회 2022 한국도로학회논문집 Vol.24 No.6

PURPOSES : The purpose of this study is to confirm the thermal expansion characteristics of concrete mixed with 1% waste glass fine aggregates, which is the amount stipulated for recycled aggregates in the current quality standard. METHODS : The coefficient of thermal expansion was measured by applying AASHTOT 336-10 using a LVDT. The results measured were used as physical properties in a finite element analysis to confirm the change in tensile stress and the displacement of the right angle section of the upper slab of a concrete pavement due to admixture substitution. RESULTS : The thermal expansion coefficients of concrete based on the replacement rate of the admixture when the waste glass fine aggregates are replaced are within the range of the thermal expansion coefficients of concrete specified in the Federal Highway Administration report. As the replacement rate of the admixture increases, the thermal expansion coefficient of concrete decreases. As the thermal expansion coefficient decreases, the slab pavement curling displacement and the tensile stress of the center of the upper slab of concrete decrease. CONCLUSIONS : In the short term, the presence or absence of waste glass fine aggregates does not significantly affect the thermal expansion coefficient of concrete. However, in the long term, waste glass fine aggregates are reactive aggregates that causes ASR, which creates an expandable gel around the aggregates and results in concrete expansion. Therefore, the relationship between ASR and the thermal expansion coefficient must be analyzed in future studies.

열 변형 해석을 위한 허니컴 샌드위치 평판의 물성치 예측에 관한 연구

홍석민(Seok-min Hong),변재기(Jae-ki Byun),최지원(Ji-won Choi),최영돈(Young-don Choi) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

Thermal problem that is directly related to the lifetime of electronic device is becoming increasingly important due to the miniaturization of electronic device. In order to solve these problems, thermal stability studies through the thermal diffusion and insulation are required. Therefore using lamination consisting of different materials or composite for getting anisotropic thermal properties is inevitable. However, using lamination causes thermal deformation because of the different coefficient of thermal expansion. Thus, in order to solve thermal problem, thermal deformation must be considered. Honeycomb sandwich plate has anisotropic thermal conductivity. To analyze thermal deformation of system that applies the honeycomb sandwich plate, thermal and elastic properties are needed. In this study, thermal and elastic properties of honeycomb sandwich plate are predicted such as coefficient of thermal expansion, elastic modulus, poisson’s ratio, shear modulus. Because properties of honeycomb sandwich plate vary according to Hexagon size, thickness and the material properties.

Characterization and controlling thermal expansion of materials with kosnarite- and langbeinite-type structures

Vladimir I. Pet’kov,Alexander S. Shipilov,Anton S. Dmitrienko,Artemy A. Alekseev 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.57 No.-

MZr2(TO4)x(PO4)3–x (M = Li, Na, K, Rb, Cs; T = As, V) solid solutions, NaFeZr(PO4)2SO4 and Pb2/3FeZr(PO4)7/3(SO4)2/3 with mineral kosnarite structure and KPbMgTi(PO4)3, K5/3MgE4/3(PO4)3 (E = Ti, Zr) with mineral langbeinite structure have been synthesized. According to the yielded results, which encompass thermal expansion data and crystallographic information about the structure of individual compounds and solid solutions, the meaningful selection of compounds with kosnarite and langbeinite structure for novel materials with controllable thermal expansion was carried out. The potassium-, rubidium-, and cesium-containing arsenates, arsenate–phosphates, vanadate–phosphates and Pb2/3FeZr(PO4)7/3(SO4)2/3 are low expansion materials (αav < 2 × 10−6 K−1); sodium–zirconium arsenate and sodium–zirconium and lithium–zirconium arsenate–phosphates, vanadate–phosphates and K5/3MgZr4/3(PO4)3 have intermediate thermal expansion (3 × 10−6 K−1 < αav < 7 × 10−6 K−1); and lithium–zirconium arsenate, KPbMgTi(PO4)3, K5/3MgTi4/3(PO4)3 are the high expansion material (αav > 7 × 10−6 K−1). The present results demonstrate that change of the size of alkali metal cation, anion substitution and varying of solid solution composition can produce kosnarite ceramics with controlled linear thermal expansion coefficients and extremely low thermal expansion anisotropy or langbeinite ceramics with isotropic expansion.

Effect of Carbon on the Coefficient of Thermal Expansion of As-Cast Fe-30wt.%Ni-12.5wt.%Co-xC Invar Alloys

Kim, Bong-Seo,Yoo, Kyung-Jae,Kim, Byung-Geol,Lee, Hee-Woong 대한금속학회 2002 METALS AND MATERIALS International Vol.8 No.3

The segregation (distribution) of nickel and the composition of its constituents influence the low thermal expansion characteristics (Invar effect) in Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy. The change of coefficient of the thermal expansion and magnetic properties were studied as an aspect of carbon addition causing the segregation of Ni in primary austenite of as-cast Fe-30 wt.% Ni-12.5 wt.% Co Invar alloy. The coefficient of thermal expansion of Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy showed its lowest value at 0.08 wt.% carbon, increased with increasing carbon content in the range of 0.08∼1.0 wt.%C, kept constant at 1.0∼2.0 wt.%C and decreased at carbon higher than 2.0 wt.%. The effective distribution of the coefficient of nickel in as-cast Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy increased with increasing carbon content. The volume fraction of they phase of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy increased with increasing carbon content. The microstructure of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy changed with the carbon content was independent of the coefficient of thermal expansion. The Curie temperature changed linearly with the carbon content and was similar to the change of the coefficient of thermal expansion. Moreover, the coefficient of thermal expansion decreased when the ratio of saturation magnetization to Curie temperature (σ_s/T_c) increased, decreasing the Curie temperature and showed a specific relationship with the magnetic properties of the Fe-30 wt.% Ni-12.5 wt.% Co-xCInvar alloy.

Root cause of thermal sleeve loosening in optimized power reactor 1000 unit 5 and 6 Part (I)

Sang-Gyu Lim,Sung-Yeop Jung,Sang-Nyung Kim 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.4

Four of safety injection (SI) nozzles in a 1000 MWe-class Optimized Power Reactor (OPR-1000) are fitted with thermal sleeves (T/S) to alleviate thermal fatigue. Thermal sleeves in #3 and #4 of Younggwang (YGN) & Ulchin (UCN) nuclear power plant are manufactured out of Inconel-600 and fitted solidly without any problem, whereas YGN and UCN in #5 and #6, also fitted with thermal sleeves made of Inconel-690 for increased corrosion resistance, experienced a loosening of thermal sleeves except T/S of YGN #5-1A. To identify the root cause of T/S loosening, three suspected causes were analyzed: (1) the shear force of flow on the T/S when the safety SI nozzle was in operation, (2) the differences between Inconel-600 and Inconel-690 in terms of physical and chemical properties (notably the thermal expansion coefficient), and (3) the positioning error in explosive expansion of the T/S as well as the asymmetric expansion of T/S. It was confirmed that none of the three suspected causes could be considered as the root cause. However, after reviewing the design change history from the Palo Verde nuclear power plant to YGN and UCN #3,4 and #5,6, it was realized that the two stage design modifications (in terms of groove depth & material) made an additional explosive energy required by 172% in aggregate, but the amount of gunpowder and the explosive expansion method were the same as before, resulting in insufficient explosive force that led to poor thermal sleeve expansion. T/S measurement data and rubbing copies also support this conclusion. And the T/S loosening was also attributable to lenient quality control before and after fitting the T/S that resulted in significant uncertainty. In addition, it is our judgment that the acceptance criterion applicable to T/S fitting was not strict enough, failing to single out thermal sleeves that were not expanded sufficiently. Lastly, the acceptance criterion was scientifically revised to incorporate the thinning effect and inherent uncertainties of measurements.

Thermal Conductivity and Thermal Expansion Behavior of Pseudo-Unidirectional and 2-Directional Quasi-Carbon Fiber/Phenolic Composites

Cho, Donghwan,Choi, Yusong,Park, Jong Kyoo,Lee, Jinyong,Yoon, Byung Il,Lim, Yun Soo The Korean Fiber Society 2004 Fibers and polymers Vol.5 No.1

In the present paper, a variety of fiber reinforcements, for instance, stabilized OXI-PAN fibers, quasi-carbon fibers, commercial carbon fibers, and their woven fabric forms, have been utilized to fabricate pseudo-unidirectional (pseudo-UD) and 2-directional (2D) phenolic matrix composites using a compression molding method. Prior to fabricating quasi-carbon fiber/phenolic (QC/P) composites, stabilized OXI-PAN fibers and fabrics were heat-treated under low temperature carbonization processes to prepare quasi-carbon fibers and fabrics. The thermal conductivity and thermal expansion/contraction behavior of QC/P composites have been investigated and compared with those of carbon fiber/phenolic (C/P) and stabilized fiber/phenolic composites. Also, the chemical compositions of the fibers used have been characterized. The results suggest that use of proper quasi-carbonization process may control effectively not only the chemical compositions of resulting quasi-carbon fibers but also the thermal conductivity and thermal expansion behavior of quasi-carbon fibers/phenolic composites in the intermediate range between stabilized PAN fiber- and carbon fiber-reinforced phenolic composites.

유화 Pilot 플랜트의 열응력 해석에 관한 연구

홍상렬(S.R. Hong),허도은(D.E. Heo),김동은(D.E. Kim),한국남(G.N. Han),황영진(Y.J. Hwang),이석순(S.S. Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

In this study, the heat transfer and the thermal stress analysis of emulsification pilot is performed. The heat transfer analysis is performed in order to obtain the temperature distribution data which were used in thermal analysis. The thermal stress analysis is performed to verify stability of the emulsification pilot plant. In other words, the thermal stress analysis is performed to see the failure and the deformation behavior of structure by thermal expansion. For the local thermal stress analysis for each parts, the attached parts are replaced with the equivalent spring which was calculated by displacement of arbitrary force. As boundary conditions for thermal stress analysis, spring stiffness of connected structure is applied for displacement constraints and temperature distribution data is applied as thermal load.

A measurement of thermal expansion-contraction characteristics of stainless steel using hightemperature digital image correlation method

레빈퉁,하넉산,구남서,전호찬 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.4

고온환경에서의 재료의 열적 성능은 고속 비행차량의 열구조 설계에 매우 중요하다. 이 연구에서의 측정방법은 재료의 열적 물리특성과 재료의 거동이 고온에서 비접촉 전영역 고온기법 측정방법을 이용하여 구축되였다. 이 측정방법은 적외선 가열 장치를 채용하여 스테인레스 스틸(s304) 샘플을 590℃ 가열하였다. 다양한 온도에서의 열적 부하로 인한 샘플표면의 이미지는 CCD 카메라를 사용하여 기록되였다. 그리고 샘플의 전영역 열변형은 디지털 영상 상관(DIC)을 이용하여 측정되였고 터멀 팽창계수(CTE) 및 수축계수 결과는 존재한 값과 비교할것이다. 비교에 의하면 CTE 는 핸드북에서 사용할수 있는 값과 접근했다. 결과에 의하면 DIC 는 기계 및 항공 우주 공학에서 전영역 고온 열변형을 측정하는것에 아주 효율적이고 정확적이였다는 것을 알수 있다. Thermal performance of materials in high-temperature environments is important for thermal-structural design of highspeed flight vehicle. In this study, the measurement method for thermal physical properties of material and the behavior of material at high temperature were established, using a non-contact and full-filed high-temperature measurement technique. This technique employs an infrared radiation heating device to heat a stainless steel (S304) sample up to 590℃. The images of the sample surface due to thermal load at various temperatures were recorded using CCD cameras. Afterwards, full-field thermal deformation of the sample was determined using digital image correlation (DIC). The results of the coefficient of thermal expansion (CTE) and contraction will be compared with exist values. According to a comparison, CTE were close to the values available in handbook. The results reveal that DIC is an effectiveness and accuracy for measuring full field high-temperature thermal deformation in mechanical and aerospace engineering.

특수 압력용기용 안전밸브의 2중 구조로 디스크의 최적설계

김창호(Chang-Ho Kim) 한국기계가공학회 2007 한국기계가공학회지 Vol.6 No.4

A safety valve is used for protecting the pressure vessel and facilities by discharging the operating fluid into the valve from the accident when the pressure is over the designated value. The fluid is sulfurous acid and nitric acid. etc. in the semi-conductor assembly line. Thus the valve elements material must be acid resistance. Teflon, which is used generally as inner parts of a valve, tends to easily sticks to sliding surface by thermal expansion under high temperature. Some studies are performed to change teflon to another material and shape to have a better fluidity under the condition. The analysis of the thermal expansion is conducted by commercial FEM software to improve the problems. Boundary conditions were temperature and load in this study. From the analysis, the thermal expansion of stainless steel is verified to be lower than that of teflon under high temperature. Thus coupled teflon/stainless steel-made valve is applied to assembly line without danger due to thermal expansion.

인산염계 매몰재에서 내화물 입도지수 변화에 따른 물리적 특성

양상욱,여인동,김교한 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.3

As castings materials for dental application, phosphate-bonded investments have been used in the casting of base metal alloy for partial denture frame work and consist essentially of fillers and binders. Fillers usually consist of quartz and/or cristobalite and binders is essentially basic MgO clinker and acidic NH₄H₂PO₄. In dental casting, the expansion of mold is a very important factor which compensate for the casting shrinkage of alloys. In order to investigate the effects of grain fineness number of silica sand on the characteristics of investments, setting time, setting temperature, setting expansion and thermal expansion of the investments were measured and to discover the reaction occurring at high temperature. From this experiment, the results obtained were as follows 1. Decreased void caused by increased grain fineness number induced shorter setting time and higher setting temperature. 2. Increased contact of filler's particle caused by increased grain fineness number induced higher setting expansion and thermal expansion. 3. Thermal expansion of investments was increased until 600℃ and at higher temperature thermal expansion was decreased by grain fineness number.