• Title, Summary, Keyword: heat treatment

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Effect of surface and heat treatment on the bond strength of veneering ceramics to zirconia(Y-TZP) (표면처리와 열처리가 전장도재와 지르코니아의 결합력에 미치는 영향)

  • Lee, Jung-Hwan;Ahn, Jae-Seok
    • The Journal of Korean Academy of Dental Technology
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    • v.35 no.4
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    • pp.271-280
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    • 2013
  • Purpose: This study was to assess the effect of surface and heat treatment on the bond strength of veneering ceramics to zirconia. Methods: The specimens were divided into 7 groups according to surface treatment and heat treatment conditions prior to porcelain application. ten specimens from each group were subjected to a 3-point flexural test. In addition the influence of surface and heat treatment on surface roughness values and phase transformation of zirconia was evaluated. Statistical analysis was performed with one-way ANOVA and post hoc Tukey's test. Results: Bond strength ranged from $20.67{\pm}3.13MPa$ to $32.69{\pm}4.52$. Bond strength of surface treatment group was lower than that of control group but only $Al_2O_3$ sandblasting group was significant difference. Bond strength of heat treatment group was higher than that of surface treatment group but there was no statistical significance. Conclusion: Bond strength of veneering ceramics to zirconia was affected by surface and heat treatment.

An Experimental Study of the Surface Treatment Effect on the Frosting/Defrosting Behavior of a Fin-Tube Heat Exchanger (휜-관 열교환기의 착.제상 거동에 대한 표면처리의 영향에 관한 실험적 연구)

  • Jhee, Sung;Lee, Kwan-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.8
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    • pp.1062-1068
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    • 2000
  • The effect of heat exchanger surface treatment on the frosting/defrosting behavior in a fin-tube heat exchanger is investigated experimentally. It is found that the hydrophilic surface mainly influences on the frosting behavior, however, the hydrophobic surface gives some influence on the defrosting behavior. In view of frosting performance, surface-treated heat exchanger with either hydrophilic or hydrophobic characteristic shows a little improvement in the thermal performance than the aluminium heat exchanger with no surface treatment. The result reveals that the heat exchanger with hydrophobic surface treatment is more effective in view of the defrosting efficiency and time. The amounts of residual water on the surface-treated heat exchangers are shown to be smaller than those of the bare heat exchanger, therefore further improvements on the performance of re-operations are expected.

Preparation and Characterization of Mesophase Pitches from Petroleum Residues using Two-step Heat Treatment (석유계 잔사유로부터 저온 2단 열처리를 이용한 메조페이스 핏치 제조 및 특성)

  • JO, HANJOO;JUNG, MIN-JUNG;LEE, HYUNG-IK;LEE, YOUNG-SEAK
    • Transactions of the Korean hydrogen and new energy society
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    • v.27 no.4
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    • pp.421-430
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    • 2016
  • To prepare mesophase pitches through low energy process, pyrolysis fuel oil with $AlCl_3$ has been modified using two-step heat treatment which is heat-treated at $330^{\circ}C$ for 3~5 h after pre-treatment at $250^{\circ}C$. The result of polarized optical microscope observation, mesophase is not observed in pitches carried out only pre-heat treatment. While mesophase content is significantly increased from 9% to 100% according to increasing secondary heat treatment time from 3 h to 5 h. Synthesizing of the mesophase pitch at low temperature of $330^{\circ}C$ is attributed to decrease of viscosity of the pitches carried out first heat treatment with $AlCl_3$. The result of Fourier-transform infrared spectroscopic analysis, it is expected that aromatization of aliphatic compounds is dominant at early secondary heat treatment, on the other hand, polycondensation reaction becomes dominant as secondary heat treatment time increases. Aromaticity and stacking height of the pitches secondary heat treated for 5 hours are more increased about 25% and 107%, respectively, than that of pitches carried out only first heat treatment.

Changes of Protopanaxadiol Ginsenosides in Ginseng Leaves by Far Infrared and Steaming Heat Treatments (원적외선 및 증숙 처리에 따른 인삼 잎의 Protopanaxadiol Ginsenosides 변화)

  • Eom, Seok-Hyun;Seo, Su-Hyun;Gimery, Amal Kumal;Jin, Cheng Wu;Kango, Eun-Young;Kang, Wie-Soo;Chung, Ill-Min;Cho, Dong-Ha
    • Korean Journal of Medicinal Crop Science
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    • v.16 no.5
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    • pp.332-336
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    • 2008
  • PPD ginsenosides in ginseng leaf were analyzed to determine effects of either FIR heat or steaming heat treatment. Among the PPD ginsenosides, Rb1, Rc and Rb3 forming four glycoside-attached aglycons were increased as FIR heat temperatures were increased from 60 to $120^{\circ}C$, while Rb3 was decreased. In addition, FIR heat treatment was effective to increase Rd forming a three glycoside-attached aglycon. Rg3 and Rh2 were not increased by the FIR heat treatment. In steaming heat treatment, Rb1 was significantly decreased, while Rb2 was increased. Rd was also increased by increased steaming temperature, yet its content was lower than in the FIR heat treatment. However, the steaming heat treatment increased yields of Rg3 and Rh2, which were not observed in the FIR heat treatment. Thus, FIR heat treatment was beneficial to efficient products of Rb1, Rc, Rb3 and Rd. Steaming heat treatment was effective to higher collection of Rb2, Rg3 and Rh2.

Effect of Vacuum Heat Treatment on Mechanical Properties of Carburized STD61 Steel (침탄된 STD61강의 기계적 성질에 미치는 진공열처리의 영향)

  • Kim, Kyung-Sik
    • Journal of the Korean Society for Heat Treatment
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    • v.30 no.1
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    • pp.17-20
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    • 2017
  • Mechanical properties of STD61 steel are compared with those of carburized STD61 steel when both are quenched and tempered in vacuum heat treatment. Mechanical properties of carburized STD61 steel are improved better than STD61 steel in hardness, tensile strength, impact energy and wear resistance.

Fabrication of Hydroxyapatite-coated Zirconia by Room Temperature Spray Process and Microstructural Change by Heat-treatment (상온 분사법에 의한 수산화아파타이트 코팅 지르코니아의 제조 및 미세구조에 미치는 열처리 효과)

  • Lee, Jong Kook;Eum, Sangcheol;Kim, Jaehong;Jang, Woo Yang
    • Journal of the Korean Society for Heat Treatment
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    • v.28 no.1
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    • pp.17-23
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    • 2015
  • Hydroxyapatite coatings were fabricated by a room temperature spray method on zirconia substrates and the influence of heat-treatment on their microstructure was also investigated. Phase composition of coated hydroxyapatite films was similar to the starting powder, but the grain size of hydroxyapatite particles was reduced to the size of nano-scale about 100 nm. Grain size, particle compactness, and adhesiveness to zirconia of hydroxyapatite coatings were increased with heat-treatment temperature, but some of cracks by heat-treatment above $1100^{\circ}C$ were initiated between hydroxyapatite coatings and zirconia substrate. Heat-treated hydroxyapatite layers show the dissolution in SBF solution for 5 days. Hydroxyapatite-coated specimen heat-treated at $1100^{\circ}C$ for 1 h has a good biocompatibility, which specimen induced the nanocrystalline hydroxyapatite precipitates on the coating surface by the immersion in SBF solution for 5 days.

Effect of Heat Treatment on the Bending Strength and Hardness of Wood

  • Won, Kyung-Rok;Kim, Tae-Hong;Hwang, Kyo-Kil;Chong, Song-Ho;Hong, Nam-Euy;Byeon, Hee-Seop
    • Journal of the Korean Wood Science and Technology
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    • v.40 no.5
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    • pp.303-310
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    • 2012
  • Heat treatment improves dimensional stability and sound absorption properties of wood. However, mechanical properties of wood can be deteriorated during the heat treatment. The effect of heat treatment on the bending strength and hardness of wood for Korean paulownia, Pinus densiflora, Lidiodendron tulipifera and Betula costata were measured. The heat treatment temperature has been investigated at $175^{\circ}C$ and $200^{\circ}C$, respectively. The results showed that the weight and density of wood decreased after heat treatment. It was found that the density by heat treatment was lower at $200^{\circ}C$ than that at $175^{\circ}C$. And, MOE increased with the reduced density. On the contrary, MOR and hardness decreased. In all conditions, It was found that there was a high correlation of 1% level between bending modulus of elasticity and modulus of rupture.

A Study on the Distortion induced by Heat Treatment on Automobile Bevel Gears (단조/절삭 베벨기어의 열처리 변형에 관한 연구)

  • 강우진;김명곤;조종래;이정환;이영선;배원병
    • Transactions of Materials Processing
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    • v.12 no.3
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    • pp.221-227
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    • 2003
  • Heat treatment is widely used in various manufacturing Processes to enhance the quality of a Product such as strength, surface hardness, and service life. In the heat treatment, there is dimensional change or distortion of the product, which critically influences the dimensional accuracy of precision parts. In this study, the distortion of a straight bevel gear induced by heat treatment is investigated in two cases. In the first case, the distortion induced by heat treatment we compared between a forged bevel gear and a machined bevel gear. In the second case, the distortion of an annealed gen is compared with that of a quenched gear. And finite element analysis has been Performed to predict the distortion of a heat-treated and machined bevel gear. The predicted values are compared with the experimental values.

Effect of Dry Heat Treatment of Red Ginseng and Red Ginseng Residue on Mycelial Growth and on Induced Tolerance of Fusarium oxysporum to Mercury Chloride (홍미삼과 홍삼정박의 건열처리가 Fusarium owsporum의 균사 생장과 승홍에 대한 내성에 미치는 영향)

  • Kim, Yeong-Ho;Park, Myeong-Han;Lee, Jong-Won
    • Journal of Ginseng Research
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    • v.16 no.2
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    • pp.99-104
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    • 1992
  • Korean red ginseng and water extract residue of red ginseng roots were treated with dry heat and incorporated in PDA medium to examine the effect of the materials on induced tolerance against mercury chloride and mycelial growth of Fusarium oxysporum. Ginseng residue was not effective in the inducement of tolerance to mercury chloride regardless of dry heat treatment. However, the heat treatment of ginseng and ginseng residues stimulated the mycelial growth of the fungus. The materials responsible for the detoxification appeared to be water-soluble. The stimulation of the fungal mycelial growth on the media by the heat treatment was highest in the water extract of ginseng. Due to the heat treatment, the mycelial growth was also slightly increased in n-hexane and methanol extracts of ginseng, compared with the ginseng fractions without dry heat treatment.

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