• Title/Summary/Keyword: Thermal shock characteristics

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Study on the characteristics of acid resistance and thermal shock for epoxy coatings (에폭시계 코팅재의 내산열충격 특성에 관한 연구)

  • Lee, Sang-Yeal;Yun, Byoung-Du
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.43 no.4
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    • pp.362-369
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    • 2007
  • This paper was studied on the characteristics of acid resistance and thermal shock for epoxy coatings in the strong acidic environment. The exhaust gas system, such as a air preheater, desulfurization equipment, for industrial boiler is damaged by dew point corrosion. To protect the acid corrosion, the coating using nonmetal was applied. The electrochemical polarization test, acid resistance and thermal shock test for epoxy coatings were carried out. And the acid resistance and thermal shock characteristics, aspect, and electrochemical anti-corrosion characteristics for epoxy coatings in the strong acidic environment were considered. The main results are as followings: As the epoxy glass flake coating by acidic thermal shock was damaged to the crack, blistering and elution etc., the current density of epoxy glass flake coating is high. But the damage of epoxy metal complex coating by acidic thermal shock was not occurred. Therefore the characteristics of acid resistance and thermal shock for epoxy metal complex coating is better than those for epoxy glass flake coating.

Fracture Characteristics of NiCr/ZrO2 Functionally Graded Material by Gas Burner Thermal Shock (가스버너 열충격에 의한 NiCr/ZrO2계 경사기능재의 열적 파괴특성)

  • Song, Jun-Hee
    • Journal of the Korean Ceramic Society
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    • v.43 no.4 s.287
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    • pp.247-252
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    • 2006
  • Joining Yittria Stabilized Zirconia (YSZ) to NiCr metal was fabricated using YSZ/NiCr Functionally Graded Materials (FGM) Interlayer by hot pressing process. Microscopic observations demonstrate that the composition and microstructure of YSZ/NiCr FGM distribute gradually in stepwise way, eliminating the macroscopic ceramic/metal interface such as that in traditional ceramic/metal joint. The thermal characteristics of this YSZ/FGM/NiCr joint were studied by thermal shock testing and therml barrier testing. Thermal shock test was conducted by gas burner rig. Acoustic Emission (AE) monitoring was performed to analyze the microfracture behavior during the thermal shock test. It could be confirmed that FGM was the excellent performance of thermal shock/barrier resistance at above $1000^{\circ}C$.

Thermal shock characteristics of work roll for cold rolling mills (냉간 압연용 Wo가 Roll의 열충격 특성)

  • 박영철;김일봉;전제영;조규섭
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.08a
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    • pp.252-261
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    • 1999
  • The troubles such as slipping, pinching and other behaviors in the service of cold rolling mills often induce thermal shock crack on the surface of work roll, and considerably reduce their service lives. In order to evaluate thermal shock resistibility we use thermal shock tester generating frictional heat caused by a rotating disc contacting with test specimens. Thermal shock produces two heat affected layers below the roll surface, one is rehardened layer and the other is succeeding tempered layer. The maximum depth of crack occurred in a thermal shocked area is a criterion for the thermal shock resistibility. This paper describes on the investigation to the influence of hardness and residual stress.

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Aluminium Titanate Sintering Study Aimed at Rational Design of Microstructure for Optimal Thermal Shock Characteristics

  • Alecu, Ioan D.;Stead, Rodney J.
    • The Korean Journal of Ceramics
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    • v.5 no.1
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    • pp.78-81
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    • 1999
  • Aluminium titanate is highly anisotropic in thermal expansion. As a result, thermal stresses build up in the material and intergranular cracks can develop. Both the outstanding thermal shock resistance and the low mechanical strength of aluminium titanate ceramics are a result of intergranular microcracking. The authors have previously identified a possibility of remarkably increasing fracture toughness of aluminium titanate without excessive penalty on strength. The paper shows that sintered density and porosity measurements can be used for optimizing the sintering and microstructure of aluminium titanate for an ideal balance between toughness and strength and, hence, the best thermal shock resistance.

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An Experimental Study on Thermal Shock Characteristics for Graphite Materials (그라파이트 재료의 열충격 특성에 대한 실험적 연구)

  • 박노석;김덕회;한영욱;김재훈;이영신;문순일
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2003.05a
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    • pp.164-167
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    • 2003
  • Thermal shock is a physical phenomenon that occurs upon a rapid, large temperature and pressure change or in the quenching condition of materials. In this study, thermal shock fracture resistance and thermal shock fracture toughness were evaluated by using laser irradiation. The temperature distribution of a specimen was detected using type K and C thermocouples. The irradiated surfaces were observed by SEM. It is concluded that the critical laser power necessary to fracture can be the major factor of thermal shock resistance and thermal shock fracture toughness of materials.

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A Study of Thermal Shock Characteristics on the Joints of Automotive Application Component using Sn-3Ag-0.5Cu Solder (Sn-3Ag-0.5Cu계 솔더를 이용한 자동차 전장 부품 접합부의 열충격 특성에 관한 연구)

  • Jeon, Yu-Jae;Son, Sun-Ik;Kim, Do-Seok;Shin, Young-Eui
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.8
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    • pp.611-616
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    • 2010
  • This study investigated the characteristics of fracture behavior and mode on solder joints before and after thermal shock test for automotive application component using Sn-3.0Ag-0.5Cu solder, which has a outstanding property as lead-free solder. The shear strength was decreased with thermal cycle number, after 432 cycles of thermal shock test. In addition, fracture mode was verified to ductile, brittle fracture and base materials fracture such as different kind fractured mode using SEM and EDS. Before the thermal shock, the fractured mode was found to typical ductile fracture in solder layer. After thermal shock test, especially, Ag was found on fractured portion as roughest surface. Moreover, it occurred delamination between a PCB and a Cu land. Before thermal shock test, most of fractured mode in solder layer has dimples by ductile fracture. However, after thermal shock test, the fractured mode became a combination of ductile and brittle fracture, and it also could find that the fracture behavior varied including delamination between substrate and Cu land.

A Study on the Thermal Shock Characteristics of the Rocket Nozzle Material (로켓 노즐 재료의 열충격특성에 관한 연구)

  • Lee, Jang-Won;Lee, Young-Shin;Kim, Jae-Hoon;Kim, Seung-Joong
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.562-566
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    • 2004
  • Thermal shock is a physical phenomenon that occurs in the condition of the exposure of a rapidly large temperature and pressure change of in the quenching condition of material. The rocket nozzle is exposed to high temperature combustion gas, it may have failure and erosion deformation. So, it is important to select a suitable material having excellent thermal shock properties and evaluate these materials in rocket design. In this study, the temperature gradient and crack initiation of rocket nozzle material is investigated using by FEM under thermal shock condition. This is very important information in the design process of thermal structure.

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Analysis of Thermal Shock and Thermal Fatigue in Tool Steels for Hot Forging (열간단조 금형강의 열충격과 열피로 특성연구)

  • 김정운;문영훈;류재화;박형호
    • Transactions of Materials Processing
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    • v.11 no.1
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    • pp.61-68
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    • 2002
  • The thermal shock and thermal fatigue test has been carried out to analyze the thermal characteristics of tool steels for hot forging and the effects of mechanical properties on this study have been investigated. The resistance to thermal shock is first of all a matter of good toughness and ductility. Therefore, a proper hot-work tool steel should be characterized by high fracture strength and high temperature toughness. Based on these results, some critical temperature($T_{fracture}$) at which fracture occur can be measured to characterize the thermal resistance of the materials. During thermal fatigue tests, the thermal fatigue cracks occur because of the repetitive heating and cooling of the die surface and the thermal fatigue damage was evaluated by analyzing different number of cycles to failure. The results showed that the resistance to thermal shock and thermal fatigue were found to be favoured by high hot tensile strength and high hot hardness, and thermal resistance of SKD61 was superior to that of ESC, SKT4 and this was caused by higher mechanical properties of SKD61.

A Study on The Degradation Characteristics of MLCCs SAC305 Lead-Free Solder Joints and Growth IMCs by Thermal Shock Test (열충격 시험을 통한 MLCCs SAC305 무연 솔더 접합부의 IMCs 성장과 접합특성 저하에 관한 연구)

  • Jung, Sang-Won;Kang, Min-Soo;Jeon, Yu-Jae;Kim, Do-Seok;Shin, Young-Eui
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.3
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    • pp.152-158
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    • 2016
  • The bonding characteristics of MLCCs (multi layer ceramic capacitor, C1608) lead-free solder (SAC305) joints were evaluated through thermal shock test ($-40^{\circ}C{\sim}125^{\circ}C$, total 1,800 cycle). After the test, IMCs( intermetallic compounds) growth and cracks were verified, also shear strengths were measured for degradation of solder joints. In addition, The thermal stress distributions at solder joints were analyzed to compare the solder joints changes before and after according to thermal shock test by FEA (finite elements analysis). We considered the effects of IMCs growth at solder joints. As results, the bonding characteristics degradation was occurred according to initial crack, crack propagations and thermal stress concentration at solder-IMCs interface, when the IMCs grown to solder inside.

Thermal Characteristic Evaluation of Functionally Graded Composites for PSZ/Metal

  • Lim, Jae-Kyoo;Song, Jun-Hee
    • Journal of Mechanical Science and Technology
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    • v.14 no.3
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    • pp.298-305
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    • 2000
  • The functionally graded material (FGM) is the new concept for a heat resisting material. FGM consists of ceramics on one side and metal on the other. A composition and microstructure of an intermediate layer change continuously from ceramics to metal at the micron level. This study is carried out to analyze the thermal shock characteristics of functionally graded PSZ/ metal composites. Heat-resistant property was evaluated by gas burner heating test using $C_2H_2/O_2$ combustion flame. The ceramic surface was heated with burner flame and the bottom surface cooled with water flow. Also, the composition profile and the thickness of the graded layer were varied to study the thermo mechanical response. Furthermore, this study carried out the thermal stress analysis to investigate the thermal characteristics by the finite element method. Acoustic emission (AE) monitoring was performed to detect the microfracture process in a thermal shock test.

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