Papers by Keyword: Brazed Joints

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Authors: Emilia Florina Binchiciu, Traian Fleşer, Ionelia Voiculescu, Aurelia Binchiciu
Abstract: The paper presents research made in order to assure additional conditions, compared to those in the general standard, to brazing rods, in order to guarantee safety for the environment and for the brazed joints, against corrosion and embrittlement, in high risk conditions. Environmental safety is ensured by limiting the amount, at 0.25% in depositions, of dangerous residual elements at: Cd<0.1%; Hg<0.1%; Pb<0.1%; Cr<0.1%; As<0.1%. The safety of structures against corrosion is provided by the alloying level of deposits and by neutralizing the coat’s activity. The structure safety towards the embrittlement of brazed joints is ensured by limiting the content of embrittling elements, namely: Sb+Fe+Bi at a maximum of 0.3% and the content of diffusible hydrogen at maximum 5 cm3/100g raw material and by limiting the coat humidity at maximum 10%. The experiments were performed to ensure the set out requirements by following the selection of raw materials on the input criteria of prohibited chemicals, reducing the water content from the elements that make up the coat and by diminishing it’s hygroscopicity by neutralizing it. Prescribing additional conditions has an effect on manufacturing costs, which requires productivity increase at brazing, diminishing work temperature, increasing the moistening capacity of products, reducing the smoke level, effects pursued by the research.
Authors: Do Won Seo, Ho Chel Yoon, Jin Yi Lee, Jae Kyoo Lim
Abstract: Ceramics are significantly used in many industrial applications due to their excellent mechanical and thermal properties such as high temperature strength, low density, high hardness, low thermal expansion and good corrosion properties. To combine the specific advantages of ceramics with that of metals, they are often used together within one composite component. In this study, the effect of temperature on fracture characteristics of silicon nitride joined to 304 stainless steel brazed with Ti active alloy are investigated in room and high temperature regions. And analytical studies on the residual stress of dissimilar brazed joint are performed by the finite element method. Four-point bending strength and deflection of interlayer increase with increasing strain rate in room temperature. As the test temperature increases, the bending strength decreases, but the deflection of interlayer is almost constant. The residual stresses redistribute after cutting of joint and the maximum tensile stress occurs on the new free surface at the ceramic near the interface. The singularity of residual stresses at the ceramic near the interface is characterized by elastic-plastic properties of ceramic and inserted materials.­
Authors: Ki Weon Kang, B.J. Lee, Kyung Young Jhang, Jung Kyu Kim
Abstract: This study was aimed at identifying failure mechanism and strength of brazed copper pipe used in household air conditioner. For these ends, the brazed joints with various brazing length were manufactured according to manufacturer’s recommended methods. The 3-dimensional X-ray technique was used to identify internal flaws and their failure mechanism in brazed joints. And, strength of brazed joint was evaluated by static tests. To evaluate the effect of heat on the brazed joints, the micro-Vickers hardness is measured. Also, bursting tests were performed for burst pressure of brazed joints by using of self-designed internal pressure bursting tester.
Authors: Ki Weon Kang, Hee Jin Shim, C.M. Kim, Jung Kyu Kim
Abstract: The study aimed at the failure analysis and strength evaluation of brazed joints used in household air conditioner. For these goals, the failure modes were investigated through the fractographic analysis and micro-Vickers hardness test. The failure modes were classified into two different types and their mechanism was influenced by heat and internal flaws such as incomplete penetration and pin holes. Also, a finite element analysis was performed to evaluate the strength behavior of the brazed joints according to the heat and internal flaws.
Authors: Jung Kyu Kim, Ki Weon Kang, Hee Jin Shim, Bum Seok Shon
Abstract: The study aimed at the fatigue life estimation for leakage of refrigerant used in household air conditioner. The leakage of brazed joints was affected by the manufacturing faults with flaws and service condition which is at the internal pressure and at the excitation. Therefore, the four point bending tests were performed to estimate effects of internal pressure and excitation for the fatigue life of brazed joints. In addition, to investigate effect of internal pressure and excitation on the fatigue life, the orthogonal array table in Design of Experiment is adopted.
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